diff --git a/.clang-format b/.clang-format
index 55ee2979d..0ca181e4a 100644
--- a/.clang-format
+++ b/.clang-format
@@ -179,4 +179,3 @@ WhitespaceSensitiveMacros:
   - PP_STRINGIZE
   - BOOST_PP_STRINGIZE
 ---
-
diff --git a/.github/workflows/release-tag.yml b/.github/workflows/release-tag.yml
index 67cc0314f..1f800408f 100644
--- a/.github/workflows/release-tag.yml
+++ b/.github/workflows/release-tag.yml
@@ -153,7 +153,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: XCode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Xcode Version
         run: xcodebuild -version
diff --git a/.github/workflows/release-tip.yml b/.github/workflows/release-tip.yml
index b97cb3c77..4b6817685 100644
--- a/.github/workflows/release-tip.yml
+++ b/.github/workflows/release-tip.yml
@@ -362,7 +362,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: Xcode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Build XCFramework
         run: nix develop -c zig build -Demit-lib-vt -Doptimize=ReleaseFast
@@ -454,7 +454,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: XCode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Xcode Version
         run: xcodebuild -version
@@ -710,7 +710,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: XCode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Xcode Version
         run: xcodebuild -version
@@ -907,7 +907,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: XCode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Xcode Version
         run: xcodebuild -version
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 107d64036..3df8e0a5b 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -335,7 +335,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: Xcode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Build XCFramework
         run: nix develop -c zig build -Demit-lib-vt
@@ -645,7 +645,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: Xcode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Build
         run: |
@@ -1077,7 +1077,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: Xcode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Xcode Version
         run: xcodebuild -version
@@ -1137,7 +1137,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: Xcode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Xcode Version
         run: xcodebuild -version
@@ -1196,9 +1196,29 @@ jobs:
       - name: Test GTK Build
         run: nix develop -c zig build -Dapp-runtime=gtk -Demit-docs -Demit-webdata
 
-      # This relies on the cache being populated by the commands above.
+        # NOTE: This used to point to the Zig global cache directory before
+        # 0.16.0. Now, the cache directory exclusively stores "minified"
+        # archives of each dependency (i.e., only the paths defined in
+        # build.zig.zon), and an uncompressed, working copy is stored in
+        # PROJECT_ROOT/zig-pkg. The zig-pkg directory is warmed up during the
+        # regular fetching process from the global cache directory if
+        # possible.
+        #
+        # Nothing else should change; zon2nix's store path mimics what a
+        # zig-pkg directory should look like, so actual build steps should be
+        # fine, it's just here where we assume that all dependencies have been
+        # downloaded, and we want to test the validity of the package
+        # directory, do we need to have it pointing to zig-pkg and not the
+        # zon2nix store path.
+        #
+        # Note that this can also be attempted by running:
+        #   zig build --fetch=needed
+        #
+        # Note that --system PKGDIR should not be added to this invocation as
+        # it disables fetching altogether (even, seemingly, from the local
+        # cache).
       - name: Test System Build
-        run: nix develop -c zig build --system ${ZIG_GLOBAL_CACHE_DIR}/p
+        run: nix develop -c zig build --system "$(realpath zig-pkg)"
 
   test-lib-vt:
     if: github.repository == 'ghostty-org/ghostty' && needs.skip.outputs.skip != 'true'
@@ -1377,7 +1397,7 @@ jobs:
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: Xcode Select
-        run: sudo xcode-select -s /Applications/Xcode_26.3.app
+        run: sudo xcode-select -s /Applications/Xcode_26.6.app
 
       - name: Xcode Version
         run: xcodebuild -version
diff --git a/.github/workflows/vouch-check-issue.yml b/.github/workflows/vouch-check-issue.yml
index 5312931e6..b096a6004 100644
--- a/.github/workflows/vouch-check-issue.yml
+++ b/.github/workflows/vouch-check-issue.yml
@@ -18,7 +18,7 @@ jobs:
         with:
           sparse-checkout: .github/issue-unvouched-message
 
-      - uses: mitchellh/vouch/action/check-issue@d66fa29a64600490892131ad87597c30c91fcac4 # unreleased main
+      - uses: mitchellh/vouch/action/check-issue@d66fa29a64600490892131ad87597c30c91fcac4 # v1.5.0
         with:
           issue-number: ${{ github.event.issue.number }}
           auto-close: true
diff --git a/.gitignore b/.gitignore
index c1e9554fc..bf57717b3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,10 +11,11 @@ zig-cache/
 .zig-cache/
 zig-pkg/
 zig-out/
+zig-pkg/
 build-cmake/
 CMakeCache.txt
 CMakeFiles/
-/build.zig.zon.bak
+build.zig.zon.bak
 /result*
 /.nixos-test-history
 example/*.wasm
@@ -30,3 +31,4 @@ glad.zip
 
 vgcore.*
 
+/sprite_face_test*
diff --git a/HACKING.md b/HACKING.md
index 8a3c22f7c..7ba584881 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -67,14 +67,6 @@ sudo xcode-select --switch /Applications/Xcode.app
 > You do not need to be running on macOS 26 to build Ghostty, you can
 > still use Xcode 26 on macOS 15 stable.
 
-> [!WARNING]
->
-> Zig 0.15.x has a [known linking issue](https://codeberg.org/ziglang/zig/issues/31658)
-> with **Xcode 26.4**. If you are on Xcode 26.4, you must use a
-> Homebrew-installed Zig (`brew install zig@0.15`) or our Nix flake,
-> both of which contain a patch that works around the issue. Alternatively,
-> you can downgrade to **Xcode 26.3**.
-
 ## AI and Agents
 
 If you're using AI assistance with Ghostty, Ghostty provides an
diff --git a/build.zig b/build.zig
index 8ef7701e2..c371119f5 100644
--- a/build.zig
+++ b/build.zig
@@ -25,9 +25,10 @@ pub fn build(b: *std.Build) !void {
     // use that as the version source of truth. Otherwise we fall back
     // to what is in the build.zig.zon.
     const file_version: ?[]const u8 = if (b.build_root.handle.readFileAlloc(
-        b.allocator,
+        b.graph.io,
         "VERSION",
-        128,
+        b.allocator,
+        .limited(128),
     )) |content| std.mem.trim(
         u8,
         content,
@@ -298,7 +299,7 @@ pub fn build(b: *std.Build) !void {
         // We need to rebuild Ghostty with a baseline CPU target.
         const valgrind_exe = exe: {
             var valgrind_config = config;
-            valgrind_config.target = valgrind_config.baselineTarget();
+            valgrind_config.target = valgrind_config.baselineTarget(b.graph.io);
             break :exe try buildpkg.GhosttyExe.init(
                 b,
                 &valgrind_config,
@@ -343,7 +344,7 @@ pub fn build(b: *std.Build) !void {
             .filters = test_filters,
             .root_module = b.createModule(.{
                 .root_source_file = b.path("src/main.zig"),
-                .target = config.baselineTarget(),
+                .target = config.baselineTarget(b.graph.io),
                 .optimize = .Debug,
                 .strip = false,
                 .omit_frame_pointer = false,
@@ -352,19 +353,18 @@ pub fn build(b: *std.Build) !void {
             // Crash on x86_64 without this
             .use_llvm = true,
         });
-        if (config.emit_test_exe) b.installArtifact(test_exe);
+        if (config.emit_test_exe) {
+            const test_exe_install = b.addInstallArtifact(test_exe, .{});
+            config.addPatchElf(test_exe, &test_exe_install.step);
+            test_step.dependOn(&test_exe_install.step);
+        }
         _ = try deps.add(test_exe);
 
-        // Verify our internal libghostty header.
-        const ghostty_h = b.addTranslateC(.{
-            .root_source_file = b.path("include/ghostty.h"),
-            .target = config.baselineTarget(),
-            .optimize = .Debug,
-        });
-        test_exe.root_module.addImport("ghostty.h", ghostty_h.createModule());
+        addGhosttyH(b, test_exe.root_module, config.baselineTarget(b.graph.io), .Debug);
 
         // Normal test running
         const test_run = b.addRunArtifact(test_exe);
+        config.addPatchElf(test_exe, &test_run.step);
         test_step.dependOn(&test_run.step);
 
         // Normal tests always test our libghostty modules
@@ -379,6 +379,7 @@ pub fn build(b: *std.Build) !void {
             "--gen-suppressions=all",
         });
         valgrind_run.addArtifactArg(test_exe);
+        config.addPatchElf(test_exe, &valgrind_run.step);
         test_valgrind_step.dependOn(&valgrind_run.step);
     }
 
@@ -390,3 +391,28 @@ pub fn build(b: *std.Build) !void {
         try translations_step.addError("cannot update translations when i18n is disabled", .{});
     }
 }
+
+fn addGhosttyH(
+    b: *std.Build,
+    module: *std.Build.Module,
+    target: std.Build.ResolvedTarget,
+    optimize: std.builtin.OptimizeMode,
+) void {
+    const translate_c = b.lazyImport(@This(), "translate_c") orelse return;
+    const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse return;
+
+    const translated: translate_c.Translator = .init(translate_c_dep, .{
+        .c_source_file = b.addWriteFiles().add(
+            "hb_c.h",
+            \\#include <ghostty.h>
+            ,
+        ),
+        .target = target,
+        .optimize = optimize,
+        .link_libc = true,
+    });
+
+    translated.addSystemIncludePath(b.path("include"));
+
+    module.addImport("ghostty.h", translated.mod);
+}
diff --git a/build.zig.zon b/build.zig.zon
index 594f1ef11..6f8287505 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -3,62 +3,71 @@
     .version = "1.3.2-dev",
     .paths = .{""},
     .fingerprint = 0x64407a2a0b4147e5,
-    .minimum_zig_version = "0.15.2",
+    .minimum_zig_version = "0.16.0",
     .dependencies = .{
-        // Zig libs
+        // External translate-c
+        // NOTE: We might not need to keep this around forever, but we need it
+        // for at least the 0.16.0 release cycle since we need fixes in
+        // Aro/translate-c itself.
+        .translate_c = .{
+            .lazy = true,
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
+        },
 
+        // Zig libs
         .libxev = .{
             // mitchellh/libxev
-            .url = "https://deps.files.ghostty.org/libxev-34fa50878aec6e5fa8f532867001ab3c36fae23e.tar.gz",
-            .hash = "libxev-0.0.0-86vtc4IcEwCqEYxEYoN_3KXmc6A9VLcm22aVImfvecYs",
+            .url = "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
+            .hash = "libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F",
             .lazy = true,
         },
         .vaxis = .{
             // rockorager/libvaxis
-            .url = "https://deps.files.ghostty.org/vaxis-7dbb9fd3122e4ffad262dd7c151d80d863b68558.tar.gz",
-            .hash = "vaxis-0.5.1-BWNV_LosCQAGmCCNOLljCIw6j6-yt53tji6n6rwJ2BhS",
+            .url = "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
+            .hash = "vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka",
             .lazy = true,
         },
         .z2d = .{
             // vancluever/z2d
-            .url = "https://deps.files.ghostty.org/z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ.tar.gz",
-            .hash = "z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ",
+            .url = "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz",
+            .hash = "z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR",
             .lazy = true,
         },
         .zig_objc = .{
             // mitchellh/zig-objc
-            .url = "https://deps.files.ghostty.org/zig_objc-f356ed02833f0f1b8e84d50bed9e807bf7cdc0ae.tar.gz",
-            .hash = "zig_objc-0.0.0-Ir_Sp5gTAQCvxxR7oVIrPXxXwsfKgVP7_wqoOQrZjFeK",
+            .url = "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
+            .hash = "zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi",
             .lazy = true,
         },
         .zig_js = .{
             // mitchellh/zig-js
-            .url = "https://deps.files.ghostty.org/zig_js-04db83c617da1956ac5adc1cb9ba1e434c1cb6fd.tar.gz",
-            .hash = "zig_js-0.0.0-rjCAV-6GAADxFug7rDmPH-uM_XcnJ5NmuAMJCAscMjhi",
+            .url = "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
+            .hash = "zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj",
             .lazy = true,
         },
         .uucode = .{
             // jacobsandlund/uucode
-            .url = "https://deps.files.ghostty.org/uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9.tar.gz",
-            .hash = "uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9",
+            .url = "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
+            .hash = "uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA",
         },
         .zig_wayland = .{
             // codeberg ifreund/zig-wayland
-            .url = "https://deps.files.ghostty.org/zig_wayland-1b5c038ec10da20ed3a15b0b2a6db1c21383e8ea.tar.gz",
-            .hash = "wayland-0.5.0-dev-lQa1khrMAQDJDwYFKpdH3HizherB7sHo5dKMECfvxQHe",
+            .url = "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz",
+            .hash = "wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX",
             .lazy = true,
         },
         .zf = .{
             // natecraddock/zf
-            .url = "https://deps.files.ghostty.org/zf-3c52637b7e937c5ae61fd679717da3e276765b23.tar.gz",
-            .hash = "zf-0.10.3-OIRy8RuJAACKA3Lohoumrt85nRbHwbpMcUaLES8vxDnh",
+            .url = "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
+            .hash = "zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW",
             .lazy = true,
         },
         .gobject = .{
             // https://github.com/ghostty-org/zig-gobject based on zig_gobject
             // Temporary until we generate them at build time automatically.
-            .url = "https://deps.files.ghostty.org/gobject-2025-11-08-23-1.tar.zst",
-            .hash = "gobject-0.3.0-Skun7ANLnwDvEfIpVmohcppXgOvg_I6YOJFmPIsKfXk-",
+            .url = "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst",
+            .hash = "gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp",
             .lazy = true,
         },
 
@@ -90,7 +99,7 @@
             .lazy = true,
         },
         .wayland_protocols = .{
-            .url = "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz",
+            .url = "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz",
             .hash = "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA",
             .lazy = true,
         },
diff --git a/build.zig.zon.json b/build.zig.zon.json
index 18137518a..e23b6f873 100644
--- a/build.zig.zon.json
+++ b/build.zig.zon.json
@@ -1,4 +1,9 @@
 {
+  "aro-0.0.0-JSD1Qk8rOQDnuVcD4jAwMpHitA6pADRKzQ7M7hKRwxvD": {
+    "name": "aro",
+    "url": "https://github.com/vancluever/arocc/archive/ecbc5c799574e0da2758a961b12efa586007f03c.tar.gz",
+    "hash": "sha256-rjNfhWjmA/1WR/xuHo4ls4fnDCbsI1VZSvb8SFRvwso="
+  },
   "N-V-__8AANT61wB--nJ95Gj_ctmzAtcjloZ__hRqNw5lC1Kr": {
     "name": "bindings",
     "url": "https://deps.files.ghostty.org/DearBindings_v0.17_ImGui_v1.92.5-docking.tar.gz",
@@ -29,10 +34,10 @@
     "url": "https://deps.files.ghostty.org/glslang-12201278a1a05c0ce0b6eb6026c65cd3e9247aa041b1c260324bf29cee559dd23ba1.tar.gz",
     "hash": "sha256-FKLtu1Ccs+UamlPj9eQ12/WXFgS0uDPmPmB26MCpl7U="
   },
-  "gobject-0.3.0-Skun7ANLnwDvEfIpVmohcppXgOvg_I6YOJFmPIsKfXk-": {
+  "gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp": {
     "name": "gobject",
-    "url": "https://deps.files.ghostty.org/gobject-2025-11-08-23-1.tar.zst",
-    "hash": "sha256-OxS9/XC5aMJj1KhOcFP1ZZN7PI4ADw4f7ocx6V64mOc="
+    "url": "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst",
+    "hash": "sha256-cZGf9a1+sDeORKWYIdzQ/5KLT7l/9pgPc2cIbqfBc4o="
   },
   "N-V-__8AALiNBAA-_0gprYr92CjrMj1I5bqNu0TSJOnjFNSr": {
     "name": "gtk4_layer_shell",
@@ -51,7 +56,7 @@
   },
   "N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI": {
     "name": "imgui",
-    "url": "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz",
+    "url": "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz",
     "hash": "sha256-yBbCDox18+Fa6Gc1DnmSVQLRpqhZOLsac7iSfl8x+cs="
   },
   "N-V-__8AALZGBAAS5NLVH-c8eC-6VtCdcH-9nUvVfUSkWS__": {
@@ -69,10 +74,10 @@
     "url": "https://deps.files.ghostty.org/libpng-1220aa013f0c83da3fb64ea6d327f9173fa008d10e28bc9349eac3463457723b1c66.tar.gz",
     "hash": "sha256-/syVtGzwXo4/yKQUdQ4LparQDYnp/fF16U/wQcrxoDo="
   },
-  "libxev-0.0.0-86vtc4IcEwCqEYxEYoN_3KXmc6A9VLcm22aVImfvecYs": {
+  "libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F": {
     "name": "libxev",
-    "url": "https://deps.files.ghostty.org/libxev-34fa50878aec6e5fa8f532867001ab3c36fae23e.tar.gz",
-    "hash": "sha256-1B9oJExVyOWRj+Y9d9eHkOBTlOYuEkcwGBUKdlgRhkg="
+    "url": "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
+    "hash": "sha256-fOU1oxIxfoEgoLuWz7fVX6M+zmqpo7gqZObWiH/aDE0="
   },
   "N-V-__8AAG3RoQEyRC2Vw7Qoro5SYBf62IHn3HjqtNVY6aWK": {
     "name": "libxml2",
@@ -109,70 +114,75 @@
     "url": "https://deps.files.ghostty.org/spirv_cross-1220fb3b5586e8be67bc3feb34cbe749cf42a60d628d2953632c2f8141302748c8da.tar.gz",
     "hash": "sha256-tStvz8Ref6abHwahNiwVVHNETizAmZVVaxVsU7pmV+M="
   },
-  "uucode-0.1.0-ZZjBPj96QADXyt5sqwBJUnhaDYs_qBeeKijZvlRa0eqM": {
-    "name": "uucode",
-    "url": "git+https://github.com/jacobsandlund/uucode#5f05f8f83a75caea201f12cc8ea32a2d82ea9732",
-    "hash": "sha256-sHPh+TQSdUGus/QTbj7KSJJkTuNTrK4VNmQDjS30Lf8="
+  "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB": {
+    "name": "translate_c",
+    "url": "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+    "hash": "sha256-i7TSSiLU9YGtLtEjgVqy2jSnKLDTeKHX+EFuXEMXJ+U="
   },
-  "uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9": {
+  "uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA": {
     "name": "uucode",
-    "url": "https://deps.files.ghostty.org/uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9.tar.gz",
-    "hash": "sha256-jLrhrmCXQ1T+LQP1JTBBB3Jn+1hCZfODbC4SdlfNdKg="
+    "url": "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
+    "hash": "sha256-R5RXW5tWIaDq5JOF2+oWd5YOYOyns6WH7f687WE+b20="
   },
-  "vaxis-0.5.1-BWNV_LosCQAGmCCNOLljCIw6j6-yt53tji6n6rwJ2BhS": {
+  "vaxis-0.6.0-BWNV_MjFCQCs9UDHiRkrgw_ayeiPkzOe4xVbaAqXkUWW": {
     "name": "vaxis",
-    "url": "https://deps.files.ghostty.org/vaxis-7dbb9fd3122e4ffad262dd7c151d80d863b68558.tar.gz",
-    "hash": "sha256-zTyrZrIffM+GJIt973tKDeWHmOCwbn7KLDdQxSiK00Y="
+    "url": "git+https://github.com/rockorager/libvaxis.git#c1e1f23be38951c425cdf31af455ba23ef178940",
+    "hash": "sha256-bIXu8lGwGo42QbItC0jOi/eN7u+f4snknBexw7dc0DI="
+  },
+  "vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka": {
+    "name": "vaxis",
+    "url": "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
+    "hash": "sha256-z3J3w+oYapfAZZR+MvWXwg+th1hePDA1TptnKFO4r+M="
   },
   "N-V-__8AAKrHGAAs2shYq8UkE6bGcR1QJtLTyOE_lcosMn6t": {
     "name": "wayland",
     "url": "https://deps.files.ghostty.org/wayland-9cb3d7aa9dc995ffafdbdef7ab86a949d0fb0e7d.tar.gz",
     "hash": "sha256-6kGR1o5DdnflHzqs3ieCmBAUTpMdOXoyfcYDXiw5xQ0="
   },
+  "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA": {
+    "name": "wayland_protocols",
+    "url": "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz",
+    "hash": "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM="
+  },
   "N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S": {
     "name": "wayland_protocols",
     "url": "https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz",
     "hash": "sha256-XO3K3egbdeYPI+XoO13SuOtO+5+Peb16NH0UiusFMPg="
   },
-  "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA": {
-    "name": "wayland_protocols",
-    "url": "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz",
-    "hash": "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM="
-  },
   "N-V-__8AAAzZywE3s51XfsLbP9eyEw57ae9swYB9aGB6fCMs": {
     "name": "wuffs",
     "url": "https://deps.files.ghostty.org/wuffs-122037b39d577ec2db3fd7b2130e7b69ef6cc1807d68607a7c232c958315d381b5cd.tar.gz",
     "hash": "sha256-nkzSCr6W5sTG7enDBXEIhgEm574uLD41UVR2wlC+HBM="
   },
-  "z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ": {
+  "z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR": {
     "name": "z2d",
-    "url": "https://deps.files.ghostty.org/z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ.tar.gz",
-    "hash": "sha256-qD+XexnAjSanRAwr5ZIaPY1aQhNW5DFVJ4PYLwhIr2E="
+    "url": "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz",
+    "hash": "sha256-/Yje2P+ro7IrPodQ26YKk7RsPSYj1Cqx6bdrmykXEKA="
   },
-  "zf-0.10.3-OIRy8RuJAACKA3Lohoumrt85nRbHwbpMcUaLES8vxDnh": {
+  "zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW": {
     "name": "zf",
-    "url": "https://deps.files.ghostty.org/zf-3c52637b7e937c5ae61fd679717da3e276765b23.tar.gz",
-    "hash": "sha256-BfAZILill3I/nBf1oWwol77N34Jcpm4hudC+XSeMgZY="
+    "url": "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
+    "hash": "sha256-LHurWwqK8jhP8AZd/CXrMJNeVsKftRCTN31/EgEgKaA="
   },
-  "zig_js-0.0.0-rjCAV-6GAADxFug7rDmPH-uM_XcnJ5NmuAMJCAscMjhi": {
+  "zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj": {
     "name": "zig_js",
-    "url": "https://deps.files.ghostty.org/zig_js-04db83c617da1956ac5adc1cb9ba1e434c1cb6fd.tar.gz",
-    "hash": "sha256-r6GdXwrv+jTu0AkTlyN/FuO+N4X+l20gsbS59wrE7V4="
+    "url": "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
+    "hash": "sha256-Q1643wb/MCX0QkPa9QEY9xeQbqpC2IOrjER0ZyL3mH0="
   },
-  "zig_objc-0.0.0-Ir_Sp5gTAQCvxxR7oVIrPXxXwsfKgVP7_wqoOQrZjFeK": {
+  "zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi": {
     "name": "zig_objc",
-    "url": "https://deps.files.ghostty.org/zig_objc-f356ed02833f0f1b8e84d50bed9e807bf7cdc0ae.tar.gz",
-    "hash": "sha256-jWFQ5BrV880qqa9KypltWuRLqNSh21rDxt6Jxp0EoMM="
+    "url": "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
+    "hash": "sha256-t8cTTJm0crcoGAyOqXO0wB2w7Yit80J2Orwr6prd/G0="
   },
-  "wayland-0.5.0-dev-lQa1khrMAQDJDwYFKpdH3HizherB7sHo5dKMECfvxQHe": {
+  "wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX": {
     "name": "zig_wayland",
-    "url": "https://deps.files.ghostty.org/zig_wayland-1b5c038ec10da20ed3a15b0b2a6db1c21383e8ea.tar.gz",
-    "hash": "sha256-1wRkixysjdFMyrATxlXdukAc34MwfNj0B6ydYVn+UKw="
+    "url": "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz",
+    "hash": "sha256-3m/ITNhZUJ/5uD/Tqm+0uZSktGoYgWF5oldOqOCUkIE="
   },
-  "zigimg-0.1.0-8_eo2vHnEwCIVW34Q14Ec-xUlzIoVg86-7FU2ypPtxms": {
+  "zigimg-0.1.0-8_eo2oyaFwBZwJpmqPkCfVXWBrHcqbYwmrp1I6bTD3lI": {
     "name": "zigimg",
-    "url": "https://github.com/ivanstepanovftw/zigimg/archive/d7b7ab0ba0899643831ef042bd73289510b39906.tar.gz",
-    "hash": "sha256-vkcTloGX+vRw7e6GYJLO9eocYaEOYjXYE0dT7jscZ4A="
+    "url": "git+https://github.com/zigimg/zigimg#d695acd97c02e57bb151e8f659d1280f5cd6ca70",
+    "hash": "sha256-0IYATQldT6eJxRR2T/2CsIYZuzomqjvmdVyjmsjguyE="
   },
   "N-V-__8AAB0eQwD-0MdOEBmz7intriBReIsIDNlukNVoNu6o": {
     "name": "zlib",
diff --git a/build.zig.zon.nix b/build.zig.zon.nix
index b3b0487b9..cfda6af29 100644
--- a/build.zig.zon.nix
+++ b/build.zig.zon.nix
@@ -6,7 +6,7 @@
   fetchurl,
   fetchgit,
   runCommandLocal,
-  zig_0_15,
+  zig_0_16,
   zstd,
   name ? "zig-packages",
 }: let
@@ -16,12 +16,16 @@
   }:
     runCommandLocal name
     {
-      nativeBuildInputs = [zig_0_15];
+      nativeBuildInputs = [zig_0_16];
     }
     ''
-      hash="$(cd "$TMPDIR" && zig fetch --global-cache-dir "$TMPDIR" ${artifact})"
-      mv "$TMPDIR/p/$hash" "$out"
-      chmod 755 "$out"
+      # workaround https://codeberg.org/ziglang/zig/issues/31866
+      # https://github.com/Cloudef/zig2nix/issues/54
+      mkdir "$TMPDIR/src" "$TMPDIR/cache"
+      touch "$TMPDIR/src/build.zig"
+      hash="$(cd "$TMPDIR/src" && zig fetch --global-cache-dir "$TMPDIR/cache" ${artifact})"
+      mkdir "$out"
+      tar zxvf "$TMPDIR/cache/p/$hash.tar.gz" --directory "$out/" --strip-components=1
     '';
 
   fetchZig = {
@@ -93,6 +97,15 @@
     fetcher.${proto};
 in
   linkFarm name [
+    {
+      name = "aro-0.0.0-JSD1Qk8rOQDnuVcD4jAwMpHitA6pADRKzQ7M7hKRwxvD";
+      path = fetchZigArtifact {
+        name = "aro";
+        url = "https://github.com/vancluever/arocc/archive/ecbc5c799574e0da2758a961b12efa586007f03c.tar.gz";
+        hash = "sha256-rjNfhWjmA/1WR/xuHo4ls4fnDCbsI1VZSvb8SFRvwso=";
+        unpack = true;
+      };
+    }
     {
       name = "N-V-__8AANT61wB--nJ95Gj_ctmzAtcjloZ__hRqNw5lC1Kr";
       path = fetchZigArtifact {
@@ -148,11 +161,11 @@ in
       };
     }
     {
-      name = "gobject-0.3.0-Skun7ANLnwDvEfIpVmohcppXgOvg_I6YOJFmPIsKfXk-";
+      name = "gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp";
       path = fetchZigArtifact {
         name = "gobject";
-        url = "https://deps.files.ghostty.org/gobject-2025-11-08-23-1.tar.zst";
-        hash = "sha256-OxS9/XC5aMJj1KhOcFP1ZZN7PI4ADw4f7ocx6V64mOc=";
+        url = "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst";
+        hash = "sha256-cZGf9a1+sDeORKWYIdzQ/5KLT7l/9pgPc2cIbqfBc4o=";
         unpack = true;
       };
     }
@@ -187,7 +200,7 @@ in
       name = "N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI";
       path = fetchZigArtifact {
         name = "imgui";
-        url = "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz";
+        url = "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz";
         hash = "sha256-yBbCDox18+Fa6Gc1DnmSVQLRpqhZOLsac7iSfl8x+cs=";
         unpack = false;
       };
@@ -220,11 +233,11 @@ in
       };
     }
     {
-      name = "libxev-0.0.0-86vtc4IcEwCqEYxEYoN_3KXmc6A9VLcm22aVImfvecYs";
+      name = "libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F";
       path = fetchZigArtifact {
         name = "libxev";
-        url = "https://deps.files.ghostty.org/libxev-34fa50878aec6e5fa8f532867001ab3c36fae23e.tar.gz";
-        hash = "sha256-1B9oJExVyOWRj+Y9d9eHkOBTlOYuEkcwGBUKdlgRhkg=";
+        url = "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz";
+        hash = "sha256-fOU1oxIxfoEgoLuWz7fVX6M+zmqpo7gqZObWiH/aDE0=";
         unpack = true;
       };
     }
@@ -292,29 +305,38 @@ in
       };
     }
     {
-      name = "uucode-0.1.0-ZZjBPj96QADXyt5sqwBJUnhaDYs_qBeeKijZvlRa0eqM";
+      name = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB";
       path = fetchZigArtifact {
-        name = "uucode";
-        url = "git+https://github.com/jacobsandlund/uucode#5f05f8f83a75caea201f12cc8ea32a2d82ea9732";
-        hash = "sha256-sHPh+TQSdUGus/QTbj7KSJJkTuNTrK4VNmQDjS30Lf8=";
+        name = "translate_c";
+        url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz";
+        hash = "sha256-i7TSSiLU9YGtLtEjgVqy2jSnKLDTeKHX+EFuXEMXJ+U=";
         unpack = true;
       };
     }
     {
-      name = "uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9";
+      name = "uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA";
       path = fetchZigArtifact {
         name = "uucode";
-        url = "https://deps.files.ghostty.org/uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9.tar.gz";
-        hash = "sha256-jLrhrmCXQ1T+LQP1JTBBB3Jn+1hCZfODbC4SdlfNdKg=";
+        url = "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz";
+        hash = "sha256-R5RXW5tWIaDq5JOF2+oWd5YOYOyns6WH7f687WE+b20=";
         unpack = true;
       };
     }
     {
-      name = "vaxis-0.5.1-BWNV_LosCQAGmCCNOLljCIw6j6-yt53tji6n6rwJ2BhS";
+      name = "vaxis-0.6.0-BWNV_MjFCQCs9UDHiRkrgw_ayeiPkzOe4xVbaAqXkUWW";
       path = fetchZigArtifact {
         name = "vaxis";
-        url = "https://deps.files.ghostty.org/vaxis-7dbb9fd3122e4ffad262dd7c151d80d863b68558.tar.gz";
-        hash = "sha256-zTyrZrIffM+GJIt973tKDeWHmOCwbn7KLDdQxSiK00Y=";
+        url = "git+https://github.com/rockorager/libvaxis.git#c1e1f23be38951c425cdf31af455ba23ef178940";
+        hash = "sha256-bIXu8lGwGo42QbItC0jOi/eN7u+f4snknBexw7dc0DI=";
+        unpack = true;
+      };
+    }
+    {
+      name = "vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka";
+      path = fetchZigArtifact {
+        name = "vaxis";
+        url = "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz";
+        hash = "sha256-z3J3w+oYapfAZZR+MvWXwg+th1hePDA1TptnKFO4r+M=";
         unpack = true;
       };
     }
@@ -327,6 +349,15 @@ in
         unpack = false;
       };
     }
+    {
+      name = "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA";
+      path = fetchZigArtifact {
+        name = "wayland_protocols";
+        url = "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz";
+        hash = "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM=";
+        unpack = false;
+      };
+    }
     {
       name = "N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S";
       path = fetchZigArtifact {
@@ -336,15 +367,6 @@ in
         unpack = false;
       };
     }
-    {
-      name = "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA";
-      path = fetchZigArtifact {
-        name = "wayland_protocols";
-        url = "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz";
-        hash = "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM=";
-        unpack = false;
-      };
-    }
     {
       name = "N-V-__8AAAzZywE3s51XfsLbP9eyEw57ae9swYB9aGB6fCMs";
       path = fetchZigArtifact {
@@ -355,56 +377,56 @@ in
       };
     }
     {
-      name = "z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ";
+      name = "z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR";
       path = fetchZigArtifact {
         name = "z2d";
-        url = "https://deps.files.ghostty.org/z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ.tar.gz";
-        hash = "sha256-qD+XexnAjSanRAwr5ZIaPY1aQhNW5DFVJ4PYLwhIr2E=";
+        url = "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz";
+        hash = "sha256-/Yje2P+ro7IrPodQ26YKk7RsPSYj1Cqx6bdrmykXEKA=";
         unpack = true;
       };
     }
     {
-      name = "zf-0.10.3-OIRy8RuJAACKA3Lohoumrt85nRbHwbpMcUaLES8vxDnh";
+      name = "zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW";
       path = fetchZigArtifact {
         name = "zf";
-        url = "https://deps.files.ghostty.org/zf-3c52637b7e937c5ae61fd679717da3e276765b23.tar.gz";
-        hash = "sha256-BfAZILill3I/nBf1oWwol77N34Jcpm4hudC+XSeMgZY=";
+        url = "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz";
+        hash = "sha256-LHurWwqK8jhP8AZd/CXrMJNeVsKftRCTN31/EgEgKaA=";
         unpack = true;
       };
     }
     {
-      name = "zig_js-0.0.0-rjCAV-6GAADxFug7rDmPH-uM_XcnJ5NmuAMJCAscMjhi";
+      name = "zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj";
       path = fetchZigArtifact {
         name = "zig_js";
-        url = "https://deps.files.ghostty.org/zig_js-04db83c617da1956ac5adc1cb9ba1e434c1cb6fd.tar.gz";
-        hash = "sha256-r6GdXwrv+jTu0AkTlyN/FuO+N4X+l20gsbS59wrE7V4=";
+        url = "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz";
+        hash = "sha256-Q1643wb/MCX0QkPa9QEY9xeQbqpC2IOrjER0ZyL3mH0=";
         unpack = true;
       };
     }
     {
-      name = "zig_objc-0.0.0-Ir_Sp5gTAQCvxxR7oVIrPXxXwsfKgVP7_wqoOQrZjFeK";
+      name = "zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi";
       path = fetchZigArtifact {
         name = "zig_objc";
-        url = "https://deps.files.ghostty.org/zig_objc-f356ed02833f0f1b8e84d50bed9e807bf7cdc0ae.tar.gz";
-        hash = "sha256-jWFQ5BrV880qqa9KypltWuRLqNSh21rDxt6Jxp0EoMM=";
+        url = "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz";
+        hash = "sha256-t8cTTJm0crcoGAyOqXO0wB2w7Yit80J2Orwr6prd/G0=";
         unpack = true;
       };
     }
     {
-      name = "wayland-0.5.0-dev-lQa1khrMAQDJDwYFKpdH3HizherB7sHo5dKMECfvxQHe";
+      name = "wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX";
       path = fetchZigArtifact {
         name = "zig_wayland";
-        url = "https://deps.files.ghostty.org/zig_wayland-1b5c038ec10da20ed3a15b0b2a6db1c21383e8ea.tar.gz";
-        hash = "sha256-1wRkixysjdFMyrATxlXdukAc34MwfNj0B6ydYVn+UKw=";
+        url = "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz";
+        hash = "sha256-3m/ITNhZUJ/5uD/Tqm+0uZSktGoYgWF5oldOqOCUkIE=";
         unpack = true;
       };
     }
     {
-      name = "zigimg-0.1.0-8_eo2vHnEwCIVW34Q14Ec-xUlzIoVg86-7FU2ypPtxms";
+      name = "zigimg-0.1.0-8_eo2oyaFwBZwJpmqPkCfVXWBrHcqbYwmrp1I6bTD3lI";
       path = fetchZigArtifact {
         name = "zigimg";
-        url = "https://github.com/ivanstepanovftw/zigimg/archive/d7b7ab0ba0899643831ef042bd73289510b39906.tar.gz";
-        hash = "sha256-vkcTloGX+vRw7e6GYJLO9eocYaEOYjXYE0dT7jscZ4A=";
+        url = "git+https://github.com/zigimg/zigimg#d695acd97c02e57bb151e8f659d1280f5cd6ca70";
+        hash = "sha256-0IYATQldT6eJxRR2T/2CsIYZuzomqjvmdVyjmsjguyE=";
         unpack = true;
       };
     }
diff --git a/build.zig.zon.txt b/build.zig.zon.txt
index cf784ad7a..dc0010aab 100644
--- a/build.zig.zon.txt
+++ b/build.zig.zon.txt
@@ -1,6 +1,9 @@
-git+https://github.com/jacobsandlund/uucode#5f05f8f83a75caea201f12cc8ea32a2d82ea9732
+git+https://github.com/rockorager/libvaxis.git#c1e1f23be38951c425cdf31af455ba23ef178940
+git+https://github.com/zigimg/zigimg#d695acd97c02e57bb151e8f659d1280f5cd6ca70
 https://deps.files.ghostty.org/DearBindings_v0.17_ImGui_v1.92.5-docking.tar.gz
 https://deps.files.ghostty.org/JetBrainsMono-2.304.tar.gz
+https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz
+https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz
 https://deps.files.ghostty.org/NerdFontsSymbolsOnly-3.4.0.tar.gz
 https://deps.files.ghostty.org/breakpad-b99f444ba5f6b98cac261cbb391d8766b34a5918.tar.gz
 https://deps.files.ghostty.org/fontconfig-2.14.2.tar.gz
@@ -8,29 +11,28 @@ https://deps.files.ghostty.org/freetype-1220b81f6ecfb3fd222f76cf9106fecfa6554ab0
 https://deps.files.ghostty.org/gettext-0.24.tar.gz
 https://deps.files.ghostty.org/ghostty-themes-release-20260713-155359-c3968b3.tgz
 https://deps.files.ghostty.org/glslang-12201278a1a05c0ce0b6eb6026c65cd3e9247aa041b1c260324bf29cee559dd23ba1.tar.gz
-https://deps.files.ghostty.org/gobject-2025-11-08-23-1.tar.zst
+https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst
 https://deps.files.ghostty.org/gtk4-layer-shell-1.1.0.tar.gz
 https://deps.files.ghostty.org/harfbuzz-11.0.0.tar.xz
 https://deps.files.ghostty.org/highway-66486a10623fa0d72fe91260f96c892e41aceb06.tar.gz
 https://deps.files.ghostty.org/libpng-1220aa013f0c83da3fb64ea6d327f9173fa008d10e28bc9349eac3463457723b1c66.tar.gz
-https://deps.files.ghostty.org/libxev-34fa50878aec6e5fa8f532867001ab3c36fae23e.tar.gz
+https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz
 https://deps.files.ghostty.org/libxml2-2.11.5.tar.gz
 https://deps.files.ghostty.org/oniguruma-1220c15e72eadd0d9085a8af134904d9a0f5dfcbed5f606ad60edc60ebeccd9706bb.tar.gz
 https://deps.files.ghostty.org/pixels-12207ff340169c7d40c570b4b6a97db614fe47e0d83b5801a932dcd44917424c8806.tar.gz
 https://deps.files.ghostty.org/plasma_wayland_protocols-12207e0851c12acdeee0991e893e0132fc87bb763969a585dc16ecca33e88334c566.tar.gz
 https://deps.files.ghostty.org/sentry-1220446be831adcca918167647c06c7b825849fa3fba5f22da394667974537a9c77e.tar.gz
 https://deps.files.ghostty.org/spirv_cross-1220fb3b5586e8be67bc3feb34cbe749cf42a60d628d2953632c2f8141302748c8da.tar.gz
-https://deps.files.ghostty.org/uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9.tar.gz
-https://deps.files.ghostty.org/vaxis-7dbb9fd3122e4ffad262dd7c151d80d863b68558.tar.gz
+https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz
+https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz
+https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz
+https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz
 https://deps.files.ghostty.org/wayland-9cb3d7aa9dc995ffafdbdef7ab86a949d0fb0e7d.tar.gz
 https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz
 https://deps.files.ghostty.org/wuffs-122037b39d577ec2db3fd7b2130e7b69ef6cc1807d68607a7c232c958315d381b5cd.tar.gz
-https://deps.files.ghostty.org/z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ.tar.gz
-https://deps.files.ghostty.org/zf-3c52637b7e937c5ae61fd679717da3e276765b23.tar.gz
-https://deps.files.ghostty.org/zig_js-04db83c617da1956ac5adc1cb9ba1e434c1cb6fd.tar.gz
-https://deps.files.ghostty.org/zig_objc-f356ed02833f0f1b8e84d50bed9e807bf7cdc0ae.tar.gz
-https://deps.files.ghostty.org/zig_wayland-1b5c038ec10da20ed3a15b0b2a6db1c21383e8ea.tar.gz
+https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz
+https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz
+https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz
+https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz
 https://deps.files.ghostty.org/zlib-1220fed0c74e1019b3ee29edae2051788b080cd96e90d56836eea857b0b966742efb.tar.gz
-https://github.com/ivanstepanovftw/zigimg/archive/d7b7ab0ba0899643831ef042bd73289510b39906.tar.gz
-https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz
-https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz
+https://github.com/vancluever/arocc/archive/ecbc5c799574e0da2758a961b12efa586007f03c.tar.gz
diff --git a/example/zig-formatter/src/main.zig b/example/zig-formatter/src/main.zig
index df21a2046..8c3fafe37 100644
--- a/example/zig-formatter/src/main.zig
+++ b/example/zig-formatter/src/main.zig
@@ -1,24 +1,20 @@
 const std = @import("std");
 const ghostty_vt = @import("ghostty-vt");
 
-pub fn main() !void {
-    var gpa: std.heap.DebugAllocator(.{}) = .init;
-    defer _ = gpa.deinit();
-    const alloc = gpa.allocator();
-
+pub fn main(init: std.process.Init) !void {
     // Create a terminal
-    var t: ghostty_vt.Terminal = try .init(alloc, .{ .cols = 150, .rows = 80 });
-    defer t.deinit(alloc);
+    var t: ghostty_vt.Terminal = try .init(init.io, init.gpa, .{ .cols = 150, .rows = 80 });
+    defer t.deinit(init.gpa);
 
     // Create a read-only VT stream for parsing terminal sequences
     var stream = t.vtStream();
     defer stream.deinit();
 
     // Read from stdin
-    const stdin = std.fs.File.stdin();
+    const stdin = std.Io.File.stdin();
     var buf: [4096]u8 = undefined;
     while (true) {
-        const n = try stdin.readAll(&buf);
+        const n = try stdin.readStreaming(init.io, &.{&buf});
         if (n == 0) break;
 
         // Replace \n with \r\n
@@ -35,7 +31,7 @@ pub fn main() !void {
     });
 
     // Write to stdout
-    var stdout_writer = std.fs.File.stdout().writer(&buf);
+    var stdout_writer = std.Io.File.stdout().writer(init.io, &buf);
     const stdout = &stdout_writer.interface;
     try stdout.print("{f}", .{formatter});
     try stdout.flush();
diff --git a/example/zig-vt-stream/src/main.zig b/example/zig-vt-stream/src/main.zig
index 87d8857dd..7202af6b8 100644
--- a/example/zig-vt-stream/src/main.zig
+++ b/example/zig-vt-stream/src/main.zig
@@ -1,13 +1,9 @@
 const std = @import("std");
 const ghostty_vt = @import("ghostty-vt");
 
-pub fn main() !void {
-    var gpa: std.heap.DebugAllocator(.{}) = .init;
-    defer _ = gpa.deinit();
-    const alloc = gpa.allocator();
-
-    var t: ghostty_vt.Terminal = try .init(alloc, .{ .cols = 80, .rows = 24 });
-    defer t.deinit(alloc);
+pub fn main(init: std.process.Init) !void {
+    var t: ghostty_vt.Terminal = try .init(init.io, init.gpa, .{ .cols = 80, .rows = 24 });
+    defer t.deinit(init.gpa);
 
     // Create a read-only VT stream for parsing terminal sequences
     var stream = t.vtStream();
@@ -34,7 +30,7 @@ pub fn main() !void {
     stream.nextSlice("Line A\r\nLine B\r\nLine C\r\n");
 
     // Get the final terminal state as a plain string
-    const str = try t.plainString(alloc);
-    defer alloc.free(str);
+    const str = try t.plainString(init.gpa);
+    defer init.gpa.free(str);
     std.debug.print("{s}\n", .{str});
 }
diff --git a/example/zig-vt/src/main.zig b/example/zig-vt/src/main.zig
index f57c70087..ee1308805 100644
--- a/example/zig-vt/src/main.zig
+++ b/example/zig-vt/src/main.zig
@@ -1,26 +1,20 @@
 const std = @import("std");
 const ghostty_vt = @import("ghostty-vt");
 
-pub fn main() !void {
-    // Use a debug allocator so we get leak checking. You probably want
-    // to replace this for release builds.
-    var gpa: std.heap.DebugAllocator(.{}) = .init;
-    defer _ = gpa.deinit();
-    const alloc = gpa.allocator();
-
+pub fn main(init: std.process.Init) !void {
     // Initialize a terminal.
-    var t: ghostty_vt.Terminal = try .init(alloc, .{
+    var t: ghostty_vt.Terminal = try .init(init.io, init.gpa, .{
         .cols = 6,
         .rows = 40,
     });
-    defer t.deinit(alloc);
+    defer t.deinit(init.gpa);
 
     // Write some text. It'll wrap because this is too long for our
     // columns size above (6).
     try t.printString("Hello, World!");
 
     // Get the plain string view of the terminal screen.
-    const str = try t.plainString(alloc);
-    defer alloc.free(str);
+    const str = try t.plainString(init.gpa);
+    defer init.gpa.free(str);
     std.debug.print("{s}\n", .{str});
 }
diff --git a/flake.lock b/flake.lock
index 410632788..ee1ca0d1e 100644
--- a/flake.lock
+++ b/flake.lock
@@ -3,11 +3,11 @@
     "flake-compat": {
       "flake": false,
       "locked": {
-        "lastModified": 1761588595,
-        "narHash": "sha256-XKUZz9zewJNUj46b4AJdiRZJAvSZ0Dqj2BNfXvFlJC4=",
+        "lastModified": 1767039857,
+        "narHash": "sha256-vNpUSpF5Nuw8xvDLj2KCwwksIbjua2LZCqhV1LNRDns=",
         "owner": "edolstra",
         "repo": "flake-compat",
-        "rev": "f387cd2afec9419c8ee37694406ca490c3f34ee5",
+        "rev": "5edf11c44bc78a0d334f6334cdaf7d60d732daab",
         "type": "github"
       },
       "original": {
@@ -23,11 +23,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1770586272,
-        "narHash": "sha256-Ucci8mu8QfxwzyfER2DQDbvW9t1BnTUJhBmY7ybralo=",
+        "lastModified": 1782657028,
+        "narHash": "sha256-PHTCpYZCMzJYS3phhywqRAZphKVr2zjvlGYa+H20ZZ4=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "b1f916ba052341edc1f80d4b2399f1092a4873ca",
+        "rev": "4ad9aaae70c9aaab504127f926c0fa9cfbc2b365",
         "type": "github"
       },
       "original": {
@@ -38,11 +38,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1770537093,
-        "narHash": "sha256-XV30uo8tXuxdzuV8l3sojmlPRLd/8tpMsOp4lNzLGUo=",
-        "rev": "fef9403a3e4d31b0a23f0bacebbec52c248fbb51",
+        "lastModified": 1782545840,
+        "narHash": "sha256-CAi8oAZaE6pTkcYQBnnOlvmfMgG/p1AO0FohKKN3J7I=",
+        "rev": "3d46470bb3030020f7e1361f33514854f5bfa86d",
         "type": "tarball",
-        "url": "https://releases.nixos.org/nixpkgs/nixpkgs-26.05pre942631.fef9403a3e4d/nixexprs.tar.xz"
+        "url": "https://releases.nixos.org/nixpkgs/nixpkgs-26.11pre1023445.3d46470bb303/nixexprs.tar.xz"
       },
       "original": {
         "type": "tarball",
@@ -88,11 +88,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1776789209,
-        "narHash": "sha256-G6B7Q4TXn7MZ1mB+f9rymjsYF5PLWoSvmbxijb/99bw=",
+        "lastModified": 1782609341,
+        "narHash": "sha256-OfCPJFS/2Z2ZyjE4adR7PL+ZEqvDQFi2XNI1L8s6wKU=",
         "owner": "mitchellh",
         "repo": "zig-overlay",
-        "rev": "14fe971844e841297ddd2ce9783d6892b467af39",
+        "rev": "5386fea92c45b154bbeb52d14ef5504f82eda86c",
         "type": "github"
       },
       "original": {
@@ -101,40 +101,18 @@
         "type": "github"
       }
     },
-    "zig_2": {
-      "inputs": {
-        "nixpkgs": [
-          "zon2nix",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1777234348,
-        "narHash": "sha256-fKw44a4qbUuI5eTG8k0gPbqMV5TOrjYF35PBzsYgd2U=",
-        "ref": "refs/heads/main",
-        "rev": "2c781c0609ecda600ab98f98cca417bbd981bd53",
-        "revCount": 1677,
-        "type": "git",
-        "url": "https://codeberg.org/jcollie/zig-overlay.git"
-      },
-      "original": {
-        "type": "git",
-        "url": "https://codeberg.org/jcollie/zig-overlay.git"
-      }
-    },
     "zon2nix": {
       "inputs": {
         "nixpkgs": [
           "nixpkgs"
-        ],
-        "zig": "zig_2"
+        ]
       },
       "locked": {
-        "lastModified": 1777314365,
-        "narHash": "sha256-eLxQaD0wc96Neqkln8wHS0rNq/chPODifFkhwrwilEU=",
+        "lastModified": 1784117571,
+        "narHash": "sha256-Hvnmnuu0VpHiZl+8z+UkMoxC7JZJvRYBqu2Asb0ZJOE=",
         "owner": "jcollie",
         "repo": "zon2nix",
-        "rev": "a5a1d412ad1ab6305511997bbc92b3a9dd6cb784",
+        "rev": "0ce628fb78309cdb13d098ae9c6fdbf87c75d25b",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 0a4e5340a..7591603f9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -74,23 +74,42 @@
     };
   in {
     devShells = forAllPlatforms (pkgs: {
-      default = pkgs.callPackage ./nix/devShell.nix {
-        zig =
-          if pkgs.stdenv.hostPlatform.isDarwin
-          then zig.packages.${pkgs.stdenv.hostPlatform.system}.brew."0.15.2"
-          else zig.packages.${pkgs.stdenv.hostPlatform.system}."0.15.2";
-        wraptest = pkgs.callPackage ./nix/pkgs/wraptest.nix {};
-        zon2nix = zon2nix;
+      default =
+        pkgs.callPackage ./nix/devShell.nix
+        (let
+          libfyaml =
+            if pkgs.stdenv.hostPlatform.isDarwin
+            then
+              pkgs.libfyaml.overrideAttrs (prev: {
+                # Manually fix libfyaml.pc until NixOS/nixpkgs#515614 is available
+                postInstall =
+                  (prev.postInstall or "")
+                  + ''
+                    substituteInPlace "$dev/lib/pkgconfig/libfyaml.pc" \
+                      --replace-fail " none required" ""
+                  '';
+              })
+            else pkgs.libfyaml;
 
-        python3 = pkgs.python3.override {
-          self = pkgs.python3;
-          packageOverrides = pyfinal: pyprev: {
-            blessed = pyfinal.callPackage ./nix/pkgs/blessed.nix {};
-            ucs-detect = pyfinal.callPackage ./nix/pkgs/ucs-detect.nix {};
-            wcwidth = pyfinal.callPackage ./nix/pkgs/wcwidth.nix {};
+          appstream = pkgs.appstream.override {libfyaml = libfyaml;};
+          libadwaita = pkgs.libadwaita.override {appstream = appstream;};
+          blueprint-compiler = pkgs.blueprint-compiler.override {libadwaita = libadwaita;};
+        in {
+          zig = zig.packages.${pkgs.stdenv.hostPlatform.system}."0.16.0";
+          wraptest = pkgs.callPackage ./nix/pkgs/wraptest.nix {};
+          zon2nix = zon2nix;
+
+          python3 = pkgs.python3.override {
+            self = pkgs.python3;
+            packageOverrides = pyfinal: pyprev: {
+              blessed = pyfinal.callPackage ./nix/pkgs/blessed.nix {};
+              ucs-detect = pyfinal.callPackage ./nix/pkgs/ucs-detect.nix {};
+              wcwidth = pyfinal.callPackage ./nix/pkgs/wcwidth.nix {};
+            };
           };
-        };
-      };
+
+          inherit appstream libadwaita blueprint-compiler;
+        });
     });
 
     packages =
diff --git a/flatpak/zig-packages.json b/flatpak/zig-packages.json
index 0d2a521c4..598e64e1a 100644
--- a/flatpak/zig-packages.json
+++ b/flatpak/zig-packages.json
@@ -1,4 +1,10 @@
 [
+  {
+    "type": "archive",
+    "url": "https://github.com/vancluever/arocc/archive/ecbc5c799574e0da2758a961b12efa586007f03c.tar.gz",
+    "dest": "vendor/p/aro-0.0.0-JSD1Qk8rOQDnuVcD4jAwMpHitA6pADRKzQ7M7hKRwxvD",
+    "sha256": "aa54487bd727e8fa36744ff0a824dedb2f4ca45f4c2d4d9d2437cf5fd3d0ad1a"
+  },
   {
     "type": "archive",
     "url": "https://deps.files.ghostty.org/DearBindings_v0.17_ImGui_v1.92.5-docking.tar.gz",
@@ -37,9 +43,9 @@
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/gobject-2025-11-08-23-1.tar.zst",
-    "dest": "vendor/p/gobject-0.3.0-Skun7ANLnwDvEfIpVmohcppXgOvg_I6YOJFmPIsKfXk-",
-    "sha256": "d9bd4306f0081d8e4b848b6adfeabd2fab49822ee2b679eb4801dcedf5d60c48"
+    "url": "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst",
+    "dest": "vendor/p/gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp",
+    "sha256": "642e324b3644c00464a2161e4af497f73cbbe8ce02a4c0edb92aacb365748047"
   },
   {
     "type": "archive",
@@ -61,7 +67,7 @@
   },
   {
     "type": "archive",
-    "url": "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz",
+    "url": "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz",
     "dest": "vendor/p/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI",
     "sha256": "c816c20e8c75f3e15ae867350e79925502d1a6a85938bb1a73b8927e5f31f9cb"
   },
@@ -85,9 +91,9 @@
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/libxev-34fa50878aec6e5fa8f532867001ab3c36fae23e.tar.gz",
-    "dest": "vendor/p/libxev-0.0.0-86vtc4IcEwCqEYxEYoN_3KXmc6A9VLcm22aVImfvecYs",
-    "sha256": "6003ea6b96e4a518a128f932327d79a11bd30996b13b73baeb29916379487dd7"
+    "url": "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
+    "dest": "vendor/p/libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F",
+    "sha256": "e2b9b224cd78101156abb8f46479a51f6cce66c4815c632856e20a1440dd02b7"
   },
   {
     "type": "archive",
@@ -131,23 +137,29 @@
     "dest": "vendor/p/N-V-__8AANb6pwD7O1WG6L5nvD_rNMvnSc9Cpg1ijSlTYywv",
     "sha256": "b52b6fcfc45e7fa69b1f06a1362c155473444e2cc09995556b156c53ba6657e3"
   },
+  {
+    "type": "archive",
+    "url": "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+    "dest": "vendor/p/translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
+    "sha256": "4fd2a2b21dbc49c22bea6854a59a7568dc77183760531ace3cf8da1267696afd"
+  },
+  {
+    "type": "archive",
+    "url": "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
+    "dest": "vendor/p/uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA",
+    "sha256": "7e76fc7fab1e7ac728c52b35bbb3e5b8c639841abfc7fe1a4bcb13050594bc9e"
+  },
   {
     "type": "git",
-    "url": "https://github.com/jacobsandlund/uucode",
-    "commit": "5f05f8f83a75caea201f12cc8ea32a2d82ea9732",
-    "dest": "vendor/p/uucode-0.1.0-ZZjBPj96QADXyt5sqwBJUnhaDYs_qBeeKijZvlRa0eqM"
+    "url": "https://github.com/rockorager/libvaxis.git",
+    "commit": "c1e1f23be38951c425cdf31af455ba23ef178940",
+    "dest": "vendor/p/vaxis-0.6.0-BWNV_MjFCQCs9UDHiRkrgw_ayeiPkzOe4xVbaAqXkUWW"
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9.tar.gz",
-    "dest": "vendor/p/uucode-0.2.0-ZZjBPqZVVABQepOqZHR7vV_NcaN-wats0IB6o-Exj6m9",
-    "sha256": "d0abee0f4f8bd6eae3c051777e16e7c42d8964aaaa015591c4e565703f465f95"
-  },
-  {
-    "type": "archive",
-    "url": "https://deps.files.ghostty.org/vaxis-7dbb9fd3122e4ffad262dd7c151d80d863b68558.tar.gz",
-    "dest": "vendor/p/vaxis-0.5.1-BWNV_LosCQAGmCCNOLljCIw6j6-yt53tji6n6rwJ2BhS",
-    "sha256": "2e72332bc89c5b541ec6e6bd48769e1f3fb757c4006f3d1af940b54f9b088ef6"
+    "url": "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
+    "dest": "vendor/p/vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka",
+    "sha256": "3ea050e905887c46bca1a2c18e41d6edf574c1aa6ebfbc5cf3c52846275e4fa8"
   },
   {
     "type": "archive",
@@ -157,15 +169,15 @@
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz",
-    "dest": "vendor/p/N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S",
-    "sha256": "5cedcadde81b75e60f23e5e83b5dd2b8eb4efb9f8f79bd7a347d148aeb0530f8"
+    "url": "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz",
+    "dest": "vendor/p/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA",
+    "sha256": "dd2df14ab5f41038257aaedcc4b5fb9ac0ee018f3f0f94af9097028e60d33223"
   },
   {
     "type": "archive",
-    "url": "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz",
-    "dest": "vendor/p/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA",
-    "sha256": "dd2df14ab5f41038257aaedcc4b5fb9ac0ee018f3f0f94af9097028e60d33223"
+    "url": "https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz",
+    "dest": "vendor/p/N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S",
+    "sha256": "5cedcadde81b75e60f23e5e83b5dd2b8eb4efb9f8f79bd7a347d148aeb0530f8"
   },
   {
     "type": "archive",
@@ -175,39 +187,39 @@
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ.tar.gz",
-    "dest": "vendor/p/z2d-0.10.0-j5P_Hu-6FgBsZNgwphIqh17jDnj8_yPtD8yzjO6PpHRQ",
-    "sha256": "69f21da2efd5ee0937fe55c4d09e48afc4fb2f91a01ef167c8c275ae046797f7"
+    "url": "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz",
+    "dest": "vendor/p/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR",
+    "sha256": "d48b117307f767ca379bf31bd171880e66dcafb89eca4a8f923222619992fcb4"
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/zf-3c52637b7e937c5ae61fd679717da3e276765b23.tar.gz",
-    "dest": "vendor/p/zf-0.10.3-OIRy8RuJAACKA3Lohoumrt85nRbHwbpMcUaLES8vxDnh",
-    "sha256": "3b015d928af04e9e26272bc15eb4dbb4d9a9d469eb6d290a0ddae673b77c4568"
+    "url": "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
+    "dest": "vendor/p/zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW",
+    "sha256": "ca4bc109fd9d97cedae2f5bdb879cc78c346d43c14a34e3a2abd2ee9208c8547"
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/zig_js-04db83c617da1956ac5adc1cb9ba1e434c1cb6fd.tar.gz",
-    "dest": "vendor/p/zig_js-0.0.0-rjCAV-6GAADxFug7rDmPH-uM_XcnJ5NmuAMJCAscMjhi",
-    "sha256": "4c2018e56015d39504b8090386ad9ce9393f38380085d9c32373bf7e56fc73a3"
+    "url": "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
+    "dest": "vendor/p/zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj",
+    "sha256": "a2ff488a244301f4e59469a5232aad6869b01acc50f7d7ed2647c029a57d4b3b"
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/zig_objc-f356ed02833f0f1b8e84d50bed9e807bf7cdc0ae.tar.gz",
-    "dest": "vendor/p/zig_objc-0.0.0-Ir_Sp5gTAQCvxxR7oVIrPXxXwsfKgVP7_wqoOQrZjFeK",
-    "sha256": "dd84af737625356fcd722cb30909f3b2e8d702667cf579714aa7eabc0ac08ecc"
+    "url": "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
+    "dest": "vendor/p/zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi",
+    "sha256": "831eaec554bb23ef20229f1e705d8f53e8a29c829840bb8d0f5edb05c76d6df0"
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/zig_wayland-1b5c038ec10da20ed3a15b0b2a6db1c21383e8ea.tar.gz",
-    "dest": "vendor/p/wayland-0.5.0-dev-lQa1khrMAQDJDwYFKpdH3HizherB7sHo5dKMECfvxQHe",
-    "sha256": "4f146b735ed0d527f520e3bf71d3e93f72c3d0fa583ae8edd3a4851f7079124e"
+    "url": "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz",
+    "dest": "vendor/p/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX",
+    "sha256": "759a632e36a948e0e412d2d74a43a69d2f34e65d40289a16af7aa3725852ef25"
   },
   {
-    "type": "archive",
-    "url": "https://github.com/ivanstepanovftw/zigimg/archive/d7b7ab0ba0899643831ef042bd73289510b39906.tar.gz",
-    "dest": "vendor/p/zigimg-0.1.0-8_eo2vHnEwCIVW34Q14Ec-xUlzIoVg86-7FU2ypPtxms",
-    "sha256": "2c1ed76ba2b35514544b0c27c9633ecba7c31be9080e37e7a010c93b5a1bc553"
+    "type": "git",
+    "url": "https://github.com/zigimg/zigimg",
+    "commit": "d695acd97c02e57bb151e8f659d1280f5cd6ca70",
+    "dest": "vendor/p/zigimg-0.1.0-8_eo2oyaFwBZwJpmqPkCfVXWBrHcqbYwmrp1I6bTD3lI"
   },
   {
     "type": "archive",
diff --git a/include/ghostty/vt/terminal.h b/include/ghostty/vt/terminal.h
index 9ae4e6c45..8470607b3 100644
--- a/include/ghostty/vt/terminal.h
+++ b/include/ghostty/vt/terminal.h
@@ -785,12 +785,13 @@ typedef enum GHOSTTY_ENUM_TYPED {
   GHOSTTY_TERMINAL_OPT_KITTY_IMAGE_MEDIUM_FILE = 16,
 
   /**
-   * Enable or disable Kitty image loading via the temporary file medium.
+   * Enable Kitty image loading via the temporary file medium, restricted to
+   * the provided directory. The string data is copied into the terminal.
    *
-   * A NULL value pointer is a no-op. Has no effect when Kitty graphics
-   * are disabled at build time.
+   * A NULL value pointer disables the temporary file medium. Has no effect
+   * when Kitty graphics are disabled at build time.
    *
-   * Input type: bool*
+   * Input type: GhosttyString*
    */
   GHOSTTY_TERMINAL_OPT_KITTY_IMAGE_MEDIUM_TEMP_FILE = 17,
 
@@ -1139,12 +1140,13 @@ typedef enum GHOSTTY_ENUM_TYPED {
   GHOSTTY_TERMINAL_DATA_KITTY_IMAGE_MEDIUM_FILE = 27,
 
   /**
-   * Whether the temporary file medium is enabled for Kitty image loading
-   * on the active screen.
+   * The directory allowed for Kitty image loading via the temporary file
+   * medium on the active screen. The string is empty when the medium is
+   * disabled.
    *
    * Returns GHOSTTY_NO_VALUE when Kitty graphics are disabled at build time.
    *
-   * Output type: bool *
+   * Output type: GhosttyString *
    */
   GHOSTTY_TERMINAL_DATA_KITTY_IMAGE_MEDIUM_TEMP_FILE = 28,
 
diff --git a/nix/build-support/check-zig-cache.sh b/nix/build-support/check-zig-cache.sh
index 9a3927846..52ab1b173 100755
--- a/nix/build-support/check-zig-cache.sh
+++ b/nix/build-support/check-zig-cache.sh
@@ -79,7 +79,7 @@ elif [ "$1" != "--update" ]; then
   exit 1
 fi
 
-zon2nix "$BUILD_ZIG_ZON" --15 --nix "$WORK_DIR/build.zig.zon.nix" --txt "$WORK_DIR/build.zig.zon.txt" --json "$WORK_DIR/build.zig.zon.json" --flatpak "$WORK_DIR/zig-packages.json"
+zon2nix "$BUILD_ZIG_ZON" --16 --nix "$WORK_DIR/build.zig.zon.nix" --txt "$WORK_DIR/build.zig.zon.txt" --json "$WORK_DIR/build.zig.zon.json" --flatpak "$WORK_DIR/zig-packages.json"
 alejandra --quiet "$WORK_DIR/build.zig.zon.nix"
 prettier --log-level warn --write "$WORK_DIR/build.zig.zon.json"
 prettier --log-level warn --write "$WORK_DIR/zig-packages.json"
diff --git a/nix/build-support/update-mirror.nu b/nix/build-support/update-mirror.nu
index 8571ddea6..b234172bf 100755
--- a/nix/build-support/update-mirror.nu
+++ b/nix/build-support/update-mirror.nu
@@ -2,23 +2,34 @@
 
 # This script downloads external dependencies from build.zig.zon.json that
 # are not already mirrored at deps.files.ghostty.org, saves them to a local
-# directory, and updates build.zig.zon to point to the new mirror URLs.
+# directory, and updates the build.zig.zon files (the root one as well as
+# every pkg/*/build.zig.zon) to point to the new mirror URLs.
 #
 # The downloaded files are unmodified so their checksums and content hashes
 # will match the originals.
 #
 # After running this script, the files in the output directory can be uploaded
-# to blob storage, and build.zig.zon will already be updated with the new URLs.
+# to blob storage, and the build.zig.zon files will already be updated with
+# the new URLs.
 def main [
   --output: string = "tmp-mirror", # Output directory for the mirrored files
   --prefix: string = "https://deps.files.ghostty.org/", # Final URL prefix to ignore
   --dry-run, # Print what would be downloaded without downloading
 ] {
   let script_dir = ($env.CURRENT_FILE | path dirname)
-  let input_file = ($script_dir | path join ".." ".." "build.zig.zon.json")
-  let zon_file = ($script_dir | path join ".." ".." "build.zig.zon")
+  let root_dir = ($script_dir | path join ".." ".." | path expand)
+  let input_file = ($root_dir | path join "build.zig.zon.json")
   let output_dir = $output
 
+  # All build.zig.zon files that may reference external URLs: the root
+  # one plus every package under pkg/. build.zig.zon.json is generated
+  # from the full dependency tree so it covers all of these.
+  let zon_files = (
+    [($root_dir | path join "build.zig.zon")]
+    | append (glob ($root_dir | path join "pkg" "*" "build.zig.zon"))
+    | sort
+  )
+
   # Ensure the output directory exists
   mkdir $output_dir
 
@@ -75,22 +86,34 @@ def main [
 
   if $dry_run {
     print "Dry run complete - no files were downloaded\n"
-    print $"Would update ($url_replacements | length) URLs in build.zig.zon"
   } else {
     print "All dependencies downloaded successfully\n"
-    print $"Updating ($zon_file)..."
-    
-    # Backup the old file
-    let backup_file = $"($zon_file).bak"
-    cp $zon_file $backup_file
-    print $"Backed up to ($backup_file)"
-    
-    mut zon_content = (open $zon_file)
-    for replacement in $url_replacements {
-      $zon_content = ($zon_content | str replace $replacement.old $replacement.new)
-    }
-    $zon_content | save -f $zon_file
+  }
 
-    print $"Updated ($url_replacements | length) URLs in build.zig.zon"
+  # Apply the URL replacements to every build.zig.zon that references them.
+  for zon_file in $zon_files {
+    mut zon_content = (open --raw $zon_file)
+    mut count = 0
+    for replacement in $url_replacements {
+      if ($zon_content | str contains $replacement.old) {
+        $zon_content = ($zon_content | str replace --all $replacement.old $replacement.new)
+        $count = $count + 1
+      }
+    }
+
+    if $count == 0 {
+      continue
+    }
+
+    let relative_path = ($zon_file | path relative-to $root_dir)
+    if $dry_run {
+      print $"Would update ($count) URLs in ($relative_path)"
+    } else {
+      # Backup the old file
+      let backup_file = $"($zon_file).bak"
+      cp $zon_file $backup_file
+      $zon_content | save -f $zon_file
+      print $"Updated ($count) URLs in ($relative_path), backup at ($relative_path).bak"
+    }
   }
 }
diff --git a/nix/devShell.nix b/nix/devShell.nix
index b530c56cd..6fa1f14b1 100644
--- a/nix/devShell.nix
+++ b/nix/devShell.nix
@@ -27,7 +27,6 @@
   wasmtime,
   wraptest,
   zig,
-  zig_0_15,
   zip,
   llvmPackages_latest,
   bzip2,
diff --git a/nix/libghostty-vt.nix b/nix/libghostty-vt.nix
index 2b67fc838..78072ed1f 100644
--- a/nix/libghostty-vt.nix
+++ b/nix/libghostty-vt.nix
@@ -11,7 +11,7 @@
   versionCheckHook,
   darwin,
   xcbuild,
-  zig_0_15,
+  zig_0_16,
   revision ? "dirty",
   optimize ? "Debug",
   simd ? true,
@@ -59,7 +59,7 @@ stdenv.mkDerivation (finalAttrs: {
     [
       git
       pkg-config
-      zig_0_15
+      zig_0_16
     ]
     ++ lib.optionals stdenv.hostPlatform.isDarwin [
       darwin.cctools
@@ -264,7 +264,7 @@ stdenv.mkDerivation (finalAttrs: {
   meta = {
     homepage = "https://ghostty.org";
     license = lib.licenses.mit;
-    platforms = zig_0_15.meta.platforms;
+    platforms = zig_0_16.meta.platforms;
     pkgConfigModules = [
       "libghostty-vt"
       "libghostty-vt-static"
diff --git a/nix/package.nix b/nix/package.nix
index fd952c9de..31db683c2 100644
--- a/nix/package.nix
+++ b/nix/package.nix
@@ -10,7 +10,7 @@
   git,
   ncurses,
   pkg-config,
-  zig_0_15,
+  zig_0_16,
   pandoc,
   revision ? "dirty",
   optimize ? "Debug",
@@ -63,7 +63,7 @@ in
         ncurses
         pandoc
         pkg-config
-        zig_0_15
+        zig_0_16
         gobject-introspection
         wrapGAppsHook4
         blueprint-compiler
diff --git a/pkg/android-ndk/build.zig b/pkg/android-ndk/build.zig
index 5b005665b..2f921e7d6 100644
--- a/pkg/android-ndk/build.zig
+++ b/pkg/android-ndk/build.zig
@@ -118,16 +118,16 @@ pub fn addPaths(b: *std.Build, step: *std.Build.Step.Compile) !void {
 
 fn findNDKPath(b: *std.Build) ?[]const u8 {
     // Check if user has set the environment variable for the NDK path.
-    if (std.process.getEnvVarOwned(b.allocator, "ANDROID_NDK_HOME") catch null) |value| {
+    if (b.graph.environ_map.get("ANDROID_NDK_HOME")) |value| {
         if (value.len == 0) return null;
-        var dir = std.fs.openDirAbsolute(value, .{}) catch return null;
-        defer dir.close();
+        var dir = std.Io.Dir.openDirAbsolute(b.graph.io, value, .{}) catch return null;
+        defer dir.close(b.graph.io);
         return value;
     }
 
     // Check the common environment variables for the Android SDK path and look for the NDK inside it.
     inline for (.{ "ANDROID_HOME", "ANDROID_SDK_ROOT" }) |env| {
-        if (std.process.getEnvVarOwned(b.allocator, env) catch null) |sdk| {
+        if (b.graph.environ_map.get(env)) |sdk| {
             if (sdk.len > 0) {
                 if (findLatestNDK(b, sdk)) |ndk| return ndk;
             }
@@ -135,10 +135,9 @@ fn findNDKPath(b: *std.Build) ?[]const u8 {
     }
 
     // As a fallback, we assume the most common/default SDK path based on the OS.
-    const home = std.process.getEnvVarOwned(
-        b.allocator,
+    const home = b.graph.environ_map.get(
         if (builtin.os.tag == .windows) "LOCALAPPDATA" else "HOME",
-    ) catch return null;
+    ) orelse return null;
 
     const default_sdk_path = b.pathJoin(
         &.{
@@ -157,8 +156,8 @@ fn findNDKPath(b: *std.Build) ?[]const u8 {
 
 fn findLatestNDK(b: *std.Build, sdk_path: []const u8) ?[]const u8 {
     const ndk_dir = b.pathJoin(&.{ sdk_path, "ndk" });
-    var dir = std.fs.openDirAbsolute(ndk_dir, .{ .iterate = true }) catch return null;
-    defer dir.close();
+    var dir = std.Io.Dir.openDirAbsolute(b.graph.io, ndk_dir, .{ .iterate = true }) catch return null;
+    defer dir.close(b.graph.io);
 
     var latest_: ?struct {
         name: []const u8,
@@ -166,7 +165,7 @@ fn findLatestNDK(b: *std.Build, sdk_path: []const u8) ?[]const u8 {
     } = null;
     var iterator = dir.iterate();
 
-    while (iterator.next() catch null) |file| {
+    while (iterator.next(b.graph.io) catch null) |file| {
         if (file.kind != .directory) continue;
         const version = std.SemanticVersion.parse(file.name) catch continue;
         if (latest_) |latest| {
diff --git a/pkg/apple-sdk/build.zig b/pkg/apple-sdk/build.zig
index f897919f4..ba49927cf 100644
--- a/pkg/apple-sdk/build.zig
+++ b/pkg/apple-sdk/build.zig
@@ -1,6 +1,31 @@
 const std = @import("std");
 const builtin = @import("builtin");
 
+// The cache. This always uses b.allocator and never frees memory
+// (which is idiomatic for a Zig build exe). We cache the libc txt
+// file we create because it is expensive to generate (subprocesses).
+pub const Cache = struct {
+    const Key = struct {
+        arch: std.Target.Cpu.Arch,
+        os: std.Target.Os.Tag,
+        abi: std.Target.Abi,
+    };
+
+    pub const Value = union(enum) {
+        native: struct {
+            libc: std.Build.LazyPath,
+            framework: []const u8,
+            system_include: []const u8,
+            library: []const u8,
+        },
+        cross: struct {
+            libc: std.Build.LazyPath,
+        },
+    };
+
+    var map: std.AutoHashMapUnmanaged(Key, ?Value) = .{};
+};
+
 pub fn build(b: *std.Build) !void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
@@ -8,40 +33,11 @@ pub fn build(b: *std.Build) !void {
     _ = optimize;
 }
 
-/// Setup the step to point to the proper Apple SDK for libc and
+/// Fetch or load the paths for the proper Apple SDK for libc and
 /// frameworks. When running on a Darwin host, this uses the native
 /// SDK installed on the system via `xcrun`. When cross-compiling from
 /// a non-Darwin host, it falls back to Zig's bundled Darwin headers.
-pub fn addPaths(
-    b: *std.Build,
-    step: *std.Build.Step.Compile,
-) !void {
-    // The cache. This always uses b.allocator and never frees memory
-    // (which is idiomatic for a Zig build exe). We cache the libc txt
-    // file we create because it is expensive to generate (subprocesses).
-    const Cache = struct {
-        const Key = struct {
-            arch: std.Target.Cpu.Arch,
-            os: std.Target.Os.Tag,
-            abi: std.Target.Abi,
-        };
-
-        const Value = union(enum) {
-            native: struct {
-                libc: std.Build.LazyPath,
-                framework: []const u8,
-                system_include: []const u8,
-                library: []const u8,
-            },
-            cross: struct {
-                libc: std.Build.LazyPath,
-            },
-        };
-
-        var map: std.AutoHashMapUnmanaged(Key, ?Value) = .{};
-    };
-
-    const target = step.rootModuleTarget();
+pub fn pathsForTarget(b: *std.Build, target: std.Target) !Cache.Value {
     const gop = try Cache.map.getOrPut(b.allocator, .{
         .arch = target.cpu.arch,
         .os = target.os.tag,
@@ -53,14 +49,18 @@ pub fn addPaths(
             // Detect our SDK using the "findNative" Zig stdlib function.
             // This is really important because it forces using `xcrun` to
             // find the SDK path.
-            const libc = std.zig.LibCInstallation.findNative(.{
-                .allocator = b.allocator,
-                .target = &step.rootModuleTarget(),
-                .verbose = false,
-            }) catch break :darwin;
+            const libc = std.zig.LibCInstallation.findNative(
+                b.allocator,
+                b.graph.io,
+                .{
+                    .environ_map = &b.graph.environ_map,
+                    .target = &target,
+                    .verbose = false,
+                },
+            ) catch break :darwin;
 
             // Render the file compatible with the `--libc` Zig flag.
-            var stream: std.io.Writer.Allocating = .init(b.allocator);
+            var stream: std.Io.Writer.Allocating = .init(b.allocator);
             defer stream.deinit();
             try libc.render(&stream.writer);
 
@@ -112,7 +112,7 @@ pub fn addPaths(
         // Fall back to Zig's bundled Darwin headers for libc resolution.
         const zig_lib_path = b.graph.zig_lib_directory.path.?;
         const include_dir = b.pathJoin(&.{
-            zig_lib_path, "libc", "include", "any-macos-any",
+            zig_lib_path, "libc", "include", "any-darwin-any",
         });
 
         const wf = b.addWriteFiles();
@@ -129,7 +129,7 @@ pub fn addPaths(
         gop.value_ptr.* = .{ .cross = .{ .libc = path } };
     }
 
-    const value = gop.value_ptr.* orelse return switch (target.os.tag) {
+    return gop.value_ptr.* orelse return switch (target.os.tag) {
         // Return a more descriptive error. Before we just returned the
         // generic error but this was confusing a lot of community members.
         // It costs us nothing in the build script to return something better.
@@ -139,8 +139,18 @@ pub fn addPaths(
         .watchos => error.XcodeWatchOSSDKNotFound,
         else => error.XcodeAppleSDKNotFound,
     };
+}
 
-    switch (value) {
+/// Setup the step to point to the proper Apple SDK for libc and
+/// frameworks. When running on a Darwin host, this uses the native
+/// SDK installed on the system via `xcrun`. When cross-compiling from
+/// a non-Darwin host, it falls back to Zig's bundled Darwin headers.
+pub fn addPaths(
+    b: *std.Build,
+    step: *std.Build.Step.Compile,
+) !void {
+    const target = step.rootModuleTarget();
+    switch (try pathsForTarget(b, target)) {
         .native => |native| {
             step.setLibCFile(native.libc);
 
diff --git a/pkg/breakpad/build.zig b/pkg/breakpad/build.zig
index 56d51b159..ce02b34fe 100644
--- a/pkg/breakpad/build.zig
+++ b/pkg/breakpad/build.zig
@@ -9,11 +9,11 @@ pub fn build(b: *std.Build) !void {
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libcpp = true,
         }),
         .linkage = .static,
     });
-    lib.linkLibCpp();
-    lib.addIncludePath(b.path("vendor"));
+    lib.root_module.addIncludePath(b.path("vendor"));
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
         try apple_sdk.addPaths(b, lib);
@@ -23,20 +23,20 @@ pub fn build(b: *std.Build) !void {
     defer flags.deinit(b.allocator);
 
     if (b.lazyDependency("breakpad", .{})) |upstream| {
-        lib.addIncludePath(upstream.path("src"));
-        lib.addCSourceFiles(.{
+        lib.root_module.addIncludePath(upstream.path("src"));
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = common,
             .flags = flags.items,
         });
 
         if (target.result.os.tag.isDarwin()) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = common_apple,
                 .flags = flags.items,
             });
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = client_apple,
                 .flags = flags.items,
@@ -44,19 +44,19 @@ pub fn build(b: *std.Build) !void {
 
             switch (target.result.os.tag) {
                 .macos => {
-                    lib.addCSourceFiles(.{
+                    lib.root_module.addCSourceFiles(.{
                         .root = upstream.path(""),
                         .files = common_mac,
                         .flags = flags.items,
                     });
-                    lib.addCSourceFiles(.{
+                    lib.root_module.addCSourceFiles(.{
                         .root = upstream.path(""),
                         .files = client_mac,
                         .flags = flags.items,
                     });
                 },
 
-                .ios => lib.addCSourceFiles(.{
+                .ios => lib.root_module.addCSourceFiles(.{
                     .root = upstream.path(""),
                     .files = client_ios,
                     .flags = flags.items,
@@ -67,12 +67,12 @@ pub fn build(b: *std.Build) !void {
         }
 
         if (target.result.os.tag == .linux) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = common_linux,
                 .flags = flags.items,
             });
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = client_linux,
                 .flags = flags.items,
diff --git a/pkg/dcimgui/build.zig b/pkg/dcimgui/build.zig
index 924e7c932..f74d3673b 100644
--- a/pkg/dcimgui/build.zig
+++ b/pkg/dcimgui/build.zig
@@ -22,18 +22,16 @@ pub fn build(b: *std.Build) !void {
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
+            // On MSVC, we must not use linkLibCpp because Zig unconditionally
+            // passes -nostdinc++ and then adds its bundled libc++/libc++abi
+            // include paths, which conflict with MSVC's own C++ runtime
+            // headers. The MSVC SDK include directories (added via linkLibC)
+            // contain both C and C++ headers, so linkLibCpp is not needed.
+            .link_libcpp = target.result.abi != .msvc,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
-    // On MSVC, we must not use linkLibCpp because Zig unconditionally
-    // passes -nostdinc++ and then adds its bundled libc++/libc++abi
-    // include paths, which conflict with MSVC's own C++ runtime headers.
-    // The MSVC SDK include directories (added via linkLibC) contain
-    // both C and C++ headers, so linkLibCpp is not needed.
-    if (target.result.abi != .msvc) {
-        lib.linkLibCpp();
-    }
     b.installArtifact(lib);
 
     // Zig module
@@ -87,8 +85,8 @@ pub fn build(b: *std.Build) !void {
 
     // Add the core Dear Imgui source files
     if (b.lazyDependency("imgui", .{})) |upstream| {
-        lib.addIncludePath(upstream.path(""));
-        lib.addCSourceFiles(.{
+        lib.root_module.addIncludePath(upstream.path(""));
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = &.{
                 "imgui_demo.cpp",
@@ -107,20 +105,20 @@ pub fn build(b: *std.Build) !void {
         );
 
         if (freetype) {
-            lib.addCSourceFile(.{
+            lib.root_module.addCSourceFile(.{
                 .file = upstream.path("misc/freetype/imgui_freetype.cpp"),
                 .flags = flags.items,
             });
 
             if (b.systemIntegrationOption("freetype", .{})) {
-                lib.linkSystemLibrary2("freetype2", dynamic_link_opts);
+                lib.root_module.linkSystemLibrary("freetype2", dynamic_link_opts);
             } else {
                 const freetype_dep = b.dependency("freetype", .{
                     .target = target,
                     .optimize = optimize,
                     .@"enable-libpng" = true,
                 });
-                lib.linkLibrary(freetype_dep.artifact("freetype"));
+                lib.root_module.linkLibrary(freetype_dep.artifact("freetype"));
                 if (freetype_dep.builder.lazyDependency(
                     "freetype",
                     .{},
@@ -131,7 +129,7 @@ pub fn build(b: *std.Build) !void {
         }
 
         if (backend_metal) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path("backends"),
                 .files = &.{"imgui_impl_metal.mm"},
                 .flags = flags.items,
@@ -143,7 +141,7 @@ pub fn build(b: *std.Build) !void {
             );
         }
         if (backend_osx) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path("backends"),
                 .files = &.{"imgui_impl_osx.mm"},
                 .flags = flags.items,
@@ -155,7 +153,7 @@ pub fn build(b: *std.Build) !void {
             );
         }
         if (backend_opengl3) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path("backends"),
                 .files = &.{"imgui_impl_opengl3.cpp"},
                 .flags = flags.items,
@@ -170,8 +168,8 @@ pub fn build(b: *std.Build) !void {
 
     // Add the C bindings
     if (b.lazyDependency("bindings", .{})) |upstream| {
-        lib.addIncludePath(upstream.path(""));
-        lib.addCSourceFiles(.{
+        lib.root_module.addIncludePath(upstream.path(""));
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = &.{
                 "dcimgui.cpp",
@@ -179,7 +177,7 @@ pub fn build(b: *std.Build) !void {
             },
             .flags = flags.items,
         });
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = b.path(""),
             .files = &.{"ext.cpp"},
             .flags = flags.items,
@@ -201,7 +199,7 @@ pub fn build(b: *std.Build) !void {
         }),
     });
     test_exe.root_module.addOptions("build_options", options);
-    test_exe.linkLibrary(lib);
+    test_exe.root_module.linkLibrary(lib);
     const tests_run = b.addRunArtifact(test_exe);
     const test_step = b.step("test", "Run tests");
     test_step.dependOn(&tests_run.step);
diff --git a/pkg/dcimgui/build.zig.zon b/pkg/dcimgui/build.zig.zon
index 95d0120e1..c488e6122 100644
--- a/pkg/dcimgui/build.zig.zon
+++ b/pkg/dcimgui/build.zig.zon
@@ -15,7 +15,7 @@
 
         .imgui = .{
             // https://github.com/ocornut/imgui
-            .url = "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz",
+            .url = "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz",
             .hash = "N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI",
             .lazy = true,
         },
diff --git a/pkg/fontconfig/build.zig b/pkg/fontconfig/build.zig
index 7c87d1f2e..cd507454f 100644
--- a/pkg/fontconfig/build.zig
+++ b/pkg/fontconfig/build.zig
@@ -41,7 +41,7 @@ pub fn build(b: *std.Build) !void {
 
     if (b.systemIntegrationOption("fontconfig", .{})) {
         module.linkSystemLibrary("fontconfig", dynamic_link_opts);
-        test_exe.linkSystemLibrary2("fontconfig", dynamic_link_opts);
+        test_exe.root_module.linkSystemLibrary("fontconfig", dynamic_link_opts);
     } else {
         const lib = try buildLib(b, module, .{
             .target = target,
@@ -54,7 +54,7 @@ pub fn build(b: *std.Build) !void {
             .dynamic_link_opts = dynamic_link_opts,
         });
 
-        test_exe.linkLibrary(lib);
+        test_exe.root_module.linkLibrary(lib);
     }
 }
 
@@ -71,15 +71,18 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
+
+    const dynamic_link_opts = options.dynamic_link_opts;
+
     if (target.result.os.tag != .windows) {
-        lib.linkSystemLibrary("pthread");
+        lib.root_module.linkSystemLibrary("pthread", dynamic_link_opts);
     }
 
-    lib.addIncludePath(b.path("override/include"));
+    lib.root_module.addIncludePath(b.path("override/include"));
     module.addIncludePath(b.path("override/include"));
 
     var flags: std.ArrayList([]const u8) = .empty;
@@ -194,19 +197,17 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         }
     }
 
-    const dynamic_link_opts = options.dynamic_link_opts;
-
     // Freetype2
     _ = b.systemIntegrationOption("freetype", .{}); // So it shows up in help
     if (freetype_enabled) {
         if (b.systemIntegrationOption("freetype", .{})) {
-            lib.linkSystemLibrary2("freetype2", dynamic_link_opts);
+            lib.root_module.linkSystemLibrary("freetype2", dynamic_link_opts);
         } else {
             if (b.lazyDependency(
                 "freetype",
                 .{ .target = target, .optimize = optimize },
             )) |freetype_dep| {
-                lib.linkLibrary(freetype_dep.artifact("freetype"));
+                lib.root_module.linkLibrary(freetype_dep.artifact("freetype"));
             }
         }
     }
@@ -227,22 +228,22 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         }
 
         if (b.systemIntegrationOption("libxml2", .{})) {
-            lib.linkSystemLibrary2("libxml-2.0", dynamic_link_opts);
+            lib.root_module.linkSystemLibrary("libxml-2.0", dynamic_link_opts);
         } else {
             if (b.lazyDependency("libxml2", .{
                 .target = target,
                 .optimize = optimize,
                 .iconv = libxml2_iconv_enabled,
             })) |libxml2_dep| {
-                lib.linkLibrary(libxml2_dep.artifact("xml2"));
+                lib.root_module.linkLibrary(libxml2_dep.artifact("xml2"));
             }
         }
     }
 
     if (b.lazyDependency("fontconfig", .{})) |upstream| {
-        lib.addIncludePath(upstream.path(""));
+        lib.root_module.addIncludePath(upstream.path(""));
         module.addIncludePath(upstream.path(""));
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = srcs,
             .flags = flags.items,
diff --git a/pkg/freetype/build.zig b/pkg/freetype/build.zig
index b85310a5b..c1f4535c7 100644
--- a/pkg/freetype/build.zig
+++ b/pkg/freetype/build.zig
@@ -39,7 +39,7 @@ pub fn build(b: *std.Build) !void {
     if (b.systemIntegrationOption("freetype", .{})) {
         module.linkSystemLibrary("freetype2", dynamic_link_opts);
         if (test_exe) |exe| {
-            exe.linkSystemLibrary2("freetype2", dynamic_link_opts);
+            exe.root_module.linkSystemLibrary("freetype2", dynamic_link_opts);
         }
     } else {
         const lib = try buildLib(b, module, .{
@@ -52,7 +52,7 @@ pub fn build(b: *std.Build) !void {
         });
 
         if (test_exe) |exe| {
-            exe.linkLibrary(lib);
+            exe.root_module.linkLibrary(lib);
         }
     }
 }
@@ -68,10 +68,10 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
         try apple_sdk.addPaths(b, lib);
@@ -101,10 +101,10 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
 
     // Zlib
     if (b.systemIntegrationOption("zlib", .{})) {
-        lib.linkSystemLibrary2("zlib", dynamic_link_opts);
+        lib.root_module.linkSystemLibrary("zlib", dynamic_link_opts);
     } else {
         const zlib_dep = b.dependency("zlib", .{ .target = target, .optimize = optimize });
-        lib.linkLibrary(zlib_dep.artifact("z"));
+        lib.root_module.linkLibrary(zlib_dep.artifact("z"));
     }
 
     // Libpng
@@ -113,50 +113,50 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         try flags.append(b.allocator, "-DFT_CONFIG_OPTION_USE_PNG=1");
 
         if (b.systemIntegrationOption("libpng", .{})) {
-            lib.linkSystemLibrary2("libpng", dynamic_link_opts);
+            lib.root_module.linkSystemLibrary("libpng", dynamic_link_opts);
         } else {
             const libpng_dep = b.dependency(
                 "libpng",
                 .{ .target = target, .optimize = optimize },
             );
-            lib.linkLibrary(libpng_dep.artifact("png"));
+            lib.root_module.linkLibrary(libpng_dep.artifact("png"));
         }
     }
 
     if (b.lazyDependency("freetype", .{})) |upstream| {
-        lib.addIncludePath(upstream.path("include"));
+        lib.root_module.addIncludePath(upstream.path("include"));
         module.addIncludePath(upstream.path("include"));
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = srcs,
             .flags = flags.items,
         });
 
         switch (target.result.os.tag) {
-            .linux => lib.addCSourceFile(.{
+            .linux => lib.root_module.addCSourceFile(.{
                 .file = upstream.path("builds/unix/ftsystem.c"),
                 .flags = flags.items,
             }),
-            .windows => lib.addCSourceFile(.{
+            .windows => lib.root_module.addCSourceFile(.{
                 .file = upstream.path("builds/windows/ftsystem.c"),
                 .flags = flags.items,
             }),
-            else => lib.addCSourceFile(.{
+            else => lib.root_module.addCSourceFile(.{
                 .file = upstream.path("src/base/ftsystem.c"),
                 .flags = flags.items,
             }),
         }
         switch (target.result.os.tag) {
             .windows => {
-                lib.addCSourceFile(.{
+                lib.root_module.addCSourceFile(.{
                     .file = upstream.path("builds/windows/ftdebug.c"),
                     .flags = flags.items,
                 });
-                lib.addWin32ResourceFile(.{
+                lib.root_module.addWin32ResourceFile(.{
                     .file = upstream.path("src/base/ftver.rc"),
                 });
             },
-            else => lib.addCSourceFile(.{
+            else => lib.root_module.addCSourceFile(.{
                 .file = upstream.path("src/base/ftdebug.c"),
                 .flags = flags.items,
             }),
diff --git a/pkg/glslang/build.zig b/pkg/glslang/build.zig
index 1dc82a6e3..92e614b1c 100644
--- a/pkg/glslang/build.zig
+++ b/pkg/glslang/build.zig
@@ -26,7 +26,7 @@ pub fn build(b: *std.Build) !void {
                 .optimize = optimize,
             }),
         });
-        test_exe.linkLibrary(lib);
+        test_exe.root_module.linkLibrary(lib);
         const tests_run = b.addRunArtifact(test_exe);
         const test_step = b.step("test", "Run tests");
         test_step.dependOn(&tests_run.step);
@@ -47,20 +47,18 @@ fn buildGlslang(
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
+            // On MSVC, we must not use linkLibCpp because Zig unconditionally
+            // passes -nostdinc++ and then adds its bundled libc++/libc++abi
+            // include paths, which conflict with MSVC's own C++ runtime
+            // headers. The MSVC SDK include directories (added via linkLibC)
+            // contain both C and C++ headers, so linkLibCpp is not needed.
+            .link_libcpp = target.result.abi != .msvc,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
-    // On MSVC, we must not use linkLibCpp because Zig unconditionally
-    // passes -nostdinc++ and then adds its bundled libc++/libc++abi
-    // include paths, which conflict with MSVC's own C++ runtime headers.
-    // The MSVC SDK include directories (added via linkLibC) contain
-    // both C and C++ headers, so linkLibCpp is not needed.
-    if (target.result.abi != .msvc) {
-        lib.linkLibCpp();
-    }
-    if (upstream_) |upstream| lib.addIncludePath(upstream.path(""));
-    lib.addIncludePath(b.path("override"));
+    if (upstream_) |upstream| lib.root_module.addIncludePath(upstream.path(""));
+    lib.root_module.addIncludePath(b.path("override"));
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
         try apple_sdk.addPaths(b, lib);
@@ -82,7 +80,7 @@ fn buildGlslang(
     }
 
     if (upstream_) |upstream| {
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .flags = flags.items,
             .files = &.{
@@ -141,7 +139,7 @@ fn buildGlslang(
         });
 
         if (target.result.os.tag != .windows) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .flags = flags.items,
                 .files = &.{
@@ -149,7 +147,7 @@ fn buildGlslang(
                 },
             });
         } else {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .flags = flags.items,
                 .files = &.{
diff --git a/pkg/gtk4-layer-shell/build.zig b/pkg/gtk4-layer-shell/build.zig
index 818b48f45..8ab67e62b 100644
--- a/pkg/gtk4-layer-shell/build.zig
+++ b/pkg/gtk4-layer-shell/build.zig
@@ -17,12 +17,32 @@ pub fn build(b: *std.Build) !void {
         .target = target,
         .optimize = optimize,
     });
-    // Needs the gtk.h header
-    module.linkSystemLibrary("gtk4", dynamic_link_opts);
 
-    if (b.systemIntegrationOption("gtk4-layer-shell", .{})) {
-        module.linkSystemLibrary("gtk4-layer-shell-0", dynamic_link_opts);
-    } else {
+    translate: {
+        const translate_c = b.lazyImport(@This(), "translate_c") orelse break :translate;
+        const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse break :translate;
+        const Translator = translate_c.Translator;
+
+        const link_system_libs_full: [2]Translator.LinkSystemLib = .{
+            .{ .name = "gtk4", .options = dynamic_link_opts },
+            .{ .name = "gtk4-layer-shell-0", .options = dynamic_link_opts },
+        };
+
+        const headers = Translator.init(translate_c_dep, .{
+            .c_source_file = b.addWriteFiles().add("c.h",
+                \\#include <gtk4-layer-shell.h>
+            ),
+            .target = target,
+            .optimize = optimize,
+            .link_system_libs = if (b.systemIntegrationOption("gtk4-layer-shell", .{}))
+                &link_system_libs_full
+            else
+                link_system_libs_full[0..1],
+        });
+        module.addImport("c", headers.mod);
+    }
+
+    if (!b.systemIntegrationOption("gtk4-layer-shell", .{})) {
         _ = try buildLib(b, module, .{
             .target = target,
             .optimize = optimize,
@@ -42,6 +62,7 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
     });
     b.installArtifact(lib);
@@ -52,13 +73,12 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
     const upstream = upstream_ orelse return lib;
     const wayland_protocols = wayland_protocols_ orelse return lib;
 
-    lib.linkLibC();
-    lib.addIncludePath(upstream.path("include"));
-    lib.addIncludePath(upstream.path("src"));
+    lib.root_module.addIncludePath(upstream.path("include"));
+    lib.root_module.addIncludePath(upstream.path("src"));
     module.addIncludePath(upstream.path("include"));
 
     // GTK
-    lib.linkSystemLibrary2("gtk4", dynamic_link_opts);
+    lib.root_module.linkSystemLibrary("gtk4", dynamic_link_opts);
 
     // Wayland headers and source files
     {
@@ -92,9 +112,9 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
             const source_scanner = b.addSystemCommand(&.{ "wayland-scanner", "private-code" });
             source_scanner.addFileArg(xml);
             const source = source_scanner.addOutputFileArg(b.fmt("{s}.c", .{name}));
-            lib.addCSourceFile(.{ .file = source });
+            lib.root_module.addCSourceFile(.{ .file = source });
         }
-        lib.addIncludePath(wf.getDirectory());
+        lib.root_module.addIncludePath(wf.getDirectory());
     }
 
     lib.installHeadersDirectory(
@@ -113,7 +133,7 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         "stubbed-surface.c",
         "xdg-surface-server.c",
     };
-    lib.addCSourceFiles(.{
+    lib.root_module.addCSourceFiles(.{
         .root = upstream.path("src"),
         .files = srcs,
         .flags = &.{
diff --git a/pkg/gtk4-layer-shell/build.zig.zon b/pkg/gtk4-layer-shell/build.zig.zon
index 9329e374f..32c7adfc1 100644
--- a/pkg/gtk4-layer-shell/build.zig.zon
+++ b/pkg/gtk4-layer-shell/build.zig.zon
@@ -14,5 +14,10 @@
             .hash = "N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S",
             .lazy = true,
         },
+        .translate_c = .{
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
+            .lazy = true,
+        },
     },
 }
diff --git a/pkg/gtk4-layer-shell/src/main.zig b/pkg/gtk4-layer-shell/src/main.zig
index a15313231..04e0f0f35 100644
--- a/pkg/gtk4-layer-shell/src/main.zig
+++ b/pkg/gtk4-layer-shell/src/main.zig
@@ -1,8 +1,6 @@
 const std = @import("std");
 
-const c = @cImport({
-    @cInclude("gtk4-layer-shell.h");
-});
+const c = @import("c");
 const gdk = @import("gdk");
 const gtk = @import("gtk");
 
diff --git a/pkg/harfbuzz/blob.zig b/pkg/harfbuzz/blob.zig
index 9472e4c75..94a6b5c98 100644
--- a/pkg/harfbuzz/blob.zig
+++ b/pkg/harfbuzz/blob.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 const Error = @import("errors.zig").Error;
 
 /// Data type holding the memory modes available to client programs.
diff --git a/pkg/harfbuzz/buffer.zig b/pkg/harfbuzz/buffer.zig
index b97c1bef4..ea70bbca8 100644
--- a/pkg/harfbuzz/buffer.zig
+++ b/pkg/harfbuzz/buffer.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 const common = @import("common.zig");
 const Error = @import("errors.zig").Error;
 const Direction = common.Direction;
diff --git a/pkg/harfbuzz/build.zig b/pkg/harfbuzz/build.zig
index b482bc8a3..5c78b262e 100644
--- a/pkg/harfbuzz/build.zig
+++ b/pkg/harfbuzz/build.zig
@@ -1,6 +1,8 @@
 const std = @import("std");
 const apple_sdk = @import("apple_sdk");
 
+const root_build_container = @This();
+
 pub fn build(b: *std.Build) !void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
@@ -8,31 +10,6 @@ pub fn build(b: *std.Build) !void {
     const coretext_enabled = b.option(bool, "enable-coretext", "Build coretext") orelse false;
     const freetype_enabled = b.option(bool, "enable-freetype", "Build freetype") orelse true;
 
-    const freetype = b.dependency("freetype", .{
-        .target = target,
-        .optimize = optimize,
-        .@"enable-libpng" = true,
-    });
-    const macos = b.dependency("macos", .{ .target = target, .optimize = optimize });
-
-    const module = harfbuzz: {
-        const module = b.addModule("harfbuzz", .{
-            .root_source_file = b.path("main.zig"),
-            .target = target,
-            .optimize = optimize,
-            .imports = &.{
-                .{ .name = "freetype", .module = freetype.module("freetype") },
-                .{ .name = "macos", .module = macos.module("macos") },
-            },
-        });
-
-        const options = b.addOptions();
-        options.addOption(bool, "coretext", coretext_enabled);
-        options.addOption(bool, "freetype", freetype_enabled);
-        module.addOptions("build_options", options);
-        break :harfbuzz module;
-    };
-
     // For dynamic linking, we prefer dynamic linking and to search by
     // mode first. Mode first will search all paths for a dynamic library
     // before falling back to static.
@@ -41,33 +18,63 @@ pub fn build(b: *std.Build) !void {
         .search_strategy = .mode_first,
     };
 
-    const test_exe = b.addTest(.{
-        .name = "test",
-        .root_module = b.createModule(.{
+    const freetype = b.dependency("freetype", .{
+        .target = target,
+        .optimize = optimize,
+        .@"enable-libpng" = true,
+    });
+
+    const module = harfbuzz: {
+        const module = b.addModule("harfbuzz", .{
             .root_source_file = b.path("main.zig"),
             .target = target,
             .optimize = optimize,
-        }),
+            .imports = if (target.result.os.tag.isDarwin())
+                &.{
+                    .{ .name = "freetype", .module = freetype.module("freetype") },
+                    .{
+                        .name = "macos",
+                        .module = b.dependency("macos", .{ .target = target, .optimize = optimize })
+                            .module("macos"),
+                    },
+                }
+            else
+                &.{
+                    .{ .name = "freetype", .module = freetype.module("freetype") },
+                },
+        });
+
+        try HarfBuzzC.addImportToModule(b, module, .{
+            .target = target,
+            .optimize = optimize,
+            .harfbuzz = if (b.systemIntegrationOption("harfbuzz", .{})) .{ .dynamic = dynamic_link_opts } else .static,
+            .coretext = coretext_enabled,
+            .freetype = if (freetype_enabled) ft: {
+                break :ft if (b.systemIntegrationOption("freetype", .{}))
+                    .{ .dynamic = dynamic_link_opts }
+                else
+                    .static;
+            } else null,
+        });
+
+        const options = b.addOptions();
+        options.addOption(bool, "coretext", coretext_enabled);
+        options.addOption(bool, "freetype", freetype_enabled);
+        module.addOptions("build_options", options);
+        break :harfbuzz module;
+    };
+
+    const test_exe = b.addTest(.{
+        .name = "test",
+        .root_module = module,
     });
 
-    {
-        var it = module.import_table.iterator();
-        while (it.next()) |entry| test_exe.root_module.addImport(entry.key_ptr.*, entry.value_ptr.*);
-        if (b.systemIntegrationOption("freetype", .{})) {
-            test_exe.linkSystemLibrary2("freetype2", dynamic_link_opts);
-        } else {
-            test_exe.linkLibrary(freetype.artifact("freetype"));
-        }
-        const tests_run = b.addRunArtifact(test_exe);
-        const test_step = b.step("test", "Run tests");
-        test_step.dependOn(&tests_run.step);
-    }
+    const tests_run = b.addRunArtifact(test_exe);
+    const test_step = b.step("test", "Run tests");
+    test_step.dependOn(&tests_run.step);
 
-    if (b.systemIntegrationOption("harfbuzz", .{})) {
-        module.linkSystemLibrary("harfbuzz", dynamic_link_opts);
-        test_exe.linkSystemLibrary2("harfbuzz", dynamic_link_opts);
-    } else {
-        const lib = try buildLib(b, module, .{
+    if (!b.systemIntegrationOption("harfbuzz", .{})) {
+        const lib = try buildLib(b, .{
             .target = target,
             .optimize = optimize,
 
@@ -77,11 +84,11 @@ pub fn build(b: *std.Build) !void {
             .dynamic_link_opts = dynamic_link_opts,
         });
 
-        test_exe.linkLibrary(lib);
+        test_exe.root_module.linkLibrary(lib);
     }
 }
 
-fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Build.Step.Compile {
+fn buildLib(b: *std.Build, options: anytype) !*std.Build.Step.Compile {
     const target = options.target;
     const optimize = options.optimize;
 
@@ -99,18 +106,16 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
+            // On MSVC, we must not use linkLibCpp because Zig unconditionally
+            // passes -nostdinc++ and then adds its bundled libc++/libc++abi
+            // include paths, which conflict with MSVC's own C++ runtime
+            // headers. The MSVC SDK include directories (added via linkLibC)
+            // contain both C and C++ headers, so linkLibCpp is not needed.
+            .link_libcpp = target.result.abi != .msvc,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
-    // On MSVC, we must not use linkLibCpp because Zig unconditionally
-    // passes -nostdinc++ and then adds its bundled libc++/libc++abi
-    // include paths, which conflict with MSVC's own C++ runtime headers.
-    // The MSVC SDK include directories (added via linkLibC) contain
-    // both C and C++ headers, so linkLibCpp is not needed.
-    if (target.result.abi != .msvc) {
-        lib.linkLibCpp();
-    }
 
     if (target.result.os.tag.isDarwin()) {
         try apple_sdk.addPaths(b, lib);
@@ -154,30 +159,20 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         });
 
         if (b.systemIntegrationOption("freetype", .{})) {
-            lib.linkSystemLibrary2("freetype2", dynamic_link_opts);
-            module.linkSystemLibrary("freetype2", dynamic_link_opts);
+            lib.root_module.linkSystemLibrary("freetype2", dynamic_link_opts);
         } else {
-            lib.linkLibrary(freetype.artifact("freetype"));
-
-            if (freetype.builder.lazyDependency(
-                "freetype",
-                .{},
-            )) |freetype_dep| {
-                module.addIncludePath(freetype_dep.path("include"));
-            }
+            lib.root_module.linkLibrary(freetype.artifact("freetype"));
         }
     }
 
     if (coretext_enabled) {
         try flags.appendSlice(b.allocator, &.{"-DHAVE_CORETEXT=1"});
-        lib.linkFramework("CoreText");
-        module.linkFramework("CoreText", .{});
+        lib.root_module.linkFramework("CoreText", .{});
     }
 
     if (b.lazyDependency("harfbuzz", .{})) |upstream| {
-        lib.addIncludePath(upstream.path("src"));
-        module.addIncludePath(upstream.path("src"));
-        lib.addCSourceFile(.{
+        lib.root_module.addIncludePath(upstream.path("src"));
+        lib.root_module.addCSourceFile(.{
             .file = upstream.path("src/harfbuzz.cc"),
             .flags = flags.items,
         });
@@ -192,3 +187,173 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
 
     return lib;
 }
+
+const HarfBuzzC = struct {
+    const AddImportToModuleOptions = struct {
+        const LinkMode = union(enum) {
+            static,
+            dynamic: std.Build.Module.LinkSystemLibraryOptions,
+        };
+
+        target: std.Build.ResolvedTarget,
+        optimize: std.builtin.OptimizeMode,
+        harfbuzz: LinkMode,
+        coretext: bool,
+        freetype: ?LinkMode,
+    };
+
+    fn fmtInclude(w: *std.Io.Writer, name: []const u8, mode: AddImportToModuleOptions.LinkMode) !void {
+        if (mode == .dynamic) {
+            try w.print("#include <{s}>\n", .{name});
+        } else {
+            try w.print("#include \"{s}\"\n", .{name});
+        }
+    }
+
+    fn addImportToModule(
+        b: *std.Build,
+        module: *std.Build.Module,
+        options: AddImportToModuleOptions,
+    ) !void {
+        // TODO: There's a decent amount of duplication here right now.
+        // Basically we want to mirror what we're passing in buildLib to make
+        // sure that the translation is generated as correct as possible.
+        // Eventually, we want to try and unravel this as much as we can, to
+        // the point that ultimately all C flags and even link options are
+        // self-contained in the translation artifact.
+        //
+        // This is a bit tricky right now as there are situations where we
+        // provide a static library built straight off of the C file, hence the
+        // duplication.
+        //
+        // NOTE: This function de-allocates nothing as b.allocator is an arena
+        // (unfortunately not documented, but a cursory search in various
+        // communities or the issue trackers should turn up confirmation).
+
+        const translate_c = b.lazyImport(root_build_container, "translate_c") orelse return;
+        const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse return;
+
+        const c_source = c_source: {
+            var source_builder: std.Io.Writer.Allocating = .init(b.allocator);
+            try fmtInclude(&source_builder.writer, "hb.h", options.harfbuzz);
+
+            if (options.coretext) {
+                try fmtInclude(&source_builder.writer, "hb-coretext.h", options.harfbuzz);
+            }
+
+            if (options.freetype != null) {
+                try fmtInclude(&source_builder.writer, "hb-ft.h", options.harfbuzz);
+            }
+
+            break :c_source source_builder.written();
+        };
+
+        // Assemble system libs
+        const system_libs = libs: {
+            var libs_builder: std.ArrayList(translate_c.Translator.LinkSystemLib) = .empty;
+            if (options.harfbuzz == .dynamic)
+                try libs_builder.append(b.allocator, .{ .name = "harfbuzz", .options = options.harfbuzz.dynamic });
+            if (options.freetype) |ft| {
+                if (ft == .dynamic)
+                    try libs_builder.append(b.allocator, .{ .name = "freetype2", .options = ft.dynamic });
+            }
+
+            break :libs libs_builder.items;
+        };
+
+        // Assemble flags
+        const flags = flags: {
+            var flag_builder: std.ArrayList([]const u8) = .empty;
+            try flag_builder.appendSlice(b.allocator, &.{
+                "-DHAVE_STDBOOL_H",
+            });
+            // Disable ubsan for MSVC: Zig's ubsan runtime cannot be bundled
+            // on Windows (LNK4229), leaving __ubsan_handle_* unresolved when
+            // the static archive is consumed by an external linker.
+            if (options.target.result.abi == .msvc) {
+                try flag_builder.appendSlice(b.allocator, &.{
+                    "-fno-sanitize=undefined",
+                    "-fno-sanitize-trap=undefined",
+                });
+            }
+            if (options.target.result.os.tag != .windows) {
+                try flag_builder.appendSlice(b.allocator, &.{
+                    "-DHAVE_UNISTD_H",
+                    "-DHAVE_SYS_MMAN_H",
+                    "-DHAVE_PTHREAD=1",
+                });
+            }
+
+            // Freetype flags/non-system include paths
+            if (options.freetype != null) {
+                try flag_builder.appendSlice(b.allocator, &.{
+                    "-DHAVE_FREETYPE=1",
+
+                    // Let's just assume a new freetype
+                    "-DHAVE_FT_GET_VAR_BLEND_COORDINATES=1",
+                    "-DHAVE_FT_SET_VAR_BLEND_COORDINATES=1",
+                    "-DHAVE_FT_DONE_MM_VAR=1",
+                    "-DHAVE_FT_GET_TRANSFORM=1",
+                });
+            }
+
+            // Coretext
+            if (options.coretext) {
+                try flag_builder.appendSlice(b.allocator, &.{"-DHAVE_CORETEXT=1"});
+                try flag_builder.appendSlice(b.allocator, &.{"-fblocks"});
+            }
+
+            break :flags flag_builder.items;
+        };
+
+        const hb_c: translate_c.Translator = .init(translate_c_dep, .{
+            .c_source_file = b.addWriteFiles().add(
+                "hb_c.h",
+                c_source,
+            ),
+            .target = options.target,
+            .optimize = options.optimize,
+            .link_libc = true,
+            .link_system_libs = system_libs,
+            .libc_file = if (options.target.result.os.tag.isDarwin()) libc_file: {
+                switch (try @import("apple_sdk").pathsForTarget(b, options.target.result)) {
+                    inline else => |paths| break :libc_file paths.libc,
+                }
+            } else null,
+            .extra_args = flags,
+        });
+
+        if (options.harfbuzz == .static) {
+            if (b.lazyDependency("harfbuzz", .{})) |upstream| {
+                hb_c.addIncludePath(upstream.path("src"));
+            }
+        }
+
+        // Freetype non-system include paths
+        if (options.freetype) |freetype_enabled| {
+            if (freetype_enabled == .static) {
+                const ft_dep = b.dependency("freetype", .{
+                    .target = options.target,
+                    .optimize = options.optimize,
+                    .@"enable-libpng" = true,
+                });
+
+                if (ft_dep.builder.lazyDependency(
+                    "freetype",
+                    .{},
+                )) |freetype_lazy_dep| {
+                    hb_c.addIncludePath(freetype_lazy_dep.path("include"));
+                }
+            }
+        }
+
+        // Coretext
+        if (options.coretext) {
+            // NOTE: We should not necessarily need to add this directly to C
+            // translation, so we just add it to the module.
+            hb_c.mod.linkFramework("CoreText", .{});
+        }
+
+        module.addImport("hb_c", hb_c.mod);
+    }
+};
diff --git a/pkg/harfbuzz/build.zig.zon b/pkg/harfbuzz/build.zig.zon
index b7d155e9c..c4ee2bdfe 100644
--- a/pkg/harfbuzz/build.zig.zon
+++ b/pkg/harfbuzz/build.zig.zon
@@ -4,6 +4,12 @@
     .fingerprint = 0xbd60917cd18865d8,
     .paths = .{""},
     .dependencies = .{
+        .translate_c = .{
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
+            .lazy = true,
+        },
+
         // harfbuzz/harfbuzz
         .harfbuzz = .{
             .url = "https://deps.files.ghostty.org/harfbuzz-11.0.0.tar.xz",
diff --git a/pkg/harfbuzz/c.zig b/pkg/harfbuzz/c.zig
deleted file mode 100644
index 49e87dce7..000000000
--- a/pkg/harfbuzz/c.zig
+++ /dev/null
@@ -1,8 +0,0 @@
-const builtin = @import("builtin");
-const build_options = @import("build_options");
-
-pub const c = @cImport({
-    @cInclude("hb.h");
-    if (build_options.freetype) @cInclude("hb-ft.h");
-    if (build_options.coretext) @cInclude("hb-coretext.h");
-});
diff --git a/pkg/harfbuzz/common.zig b/pkg/harfbuzz/common.zig
index 840ff5868..01955907a 100644
--- a/pkg/harfbuzz/common.zig
+++ b/pkg/harfbuzz/common.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 
 /// The direction of a text segment or buffer.
 ///
diff --git a/pkg/harfbuzz/coretext.zig b/pkg/harfbuzz/coretext.zig
index 73042624c..72dfd53b2 100644
--- a/pkg/harfbuzz/coretext.zig
+++ b/pkg/harfbuzz/coretext.zig
@@ -1,6 +1,6 @@
 const macos = @import("macos");
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 const Face = @import("face.zig").Face;
 const Font = @import("font.zig").Font;
 const Error = @import("errors.zig").Error;
diff --git a/pkg/harfbuzz/face.zig b/pkg/harfbuzz/face.zig
index 5ffad5d3e..942894b92 100644
--- a/pkg/harfbuzz/face.zig
+++ b/pkg/harfbuzz/face.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 
 /// A font face is an object that represents a single face from within a font family.
 ///
diff --git a/pkg/harfbuzz/font.zig b/pkg/harfbuzz/font.zig
index 13544fb9f..4202ca4dd 100644
--- a/pkg/harfbuzz/font.zig
+++ b/pkg/harfbuzz/font.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 const Face = @import("face.zig").Face;
 const Error = @import("errors.zig").Error;
 
diff --git a/pkg/harfbuzz/freetype.zig b/pkg/harfbuzz/freetype.zig
index d90d3f83c..65419a6e6 100644
--- a/pkg/harfbuzz/freetype.zig
+++ b/pkg/harfbuzz/freetype.zig
@@ -1,6 +1,6 @@
 const freetype = @import("freetype");
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 const Face = @import("face.zig").Face;
 const Font = @import("font.zig").Font;
 const Error = @import("errors.zig").Error;
diff --git a/pkg/harfbuzz/main.zig b/pkg/harfbuzz/main.zig
index 08a4f9c2a..6e46eb42c 100644
--- a/pkg/harfbuzz/main.zig
+++ b/pkg/harfbuzz/main.zig
@@ -7,7 +7,7 @@ const font = @import("font.zig");
 const shapepkg = @import("shape.zig");
 const versionpkg = @import("version.zig");
 
-pub const c = @import("c.zig").c;
+pub const c = @import("hb_c");
 pub const freetype = @import("freetype.zig");
 pub const coretext = @import("coretext.zig");
 pub const MemoryMode = blob.MemoryMode;
diff --git a/pkg/harfbuzz/shape.zig b/pkg/harfbuzz/shape.zig
index b49020c3c..38f56c4ac 100644
--- a/pkg/harfbuzz/shape.zig
+++ b/pkg/harfbuzz/shape.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 const Font = @import("font.zig").Font;
 const Buffer = @import("buffer.zig").Buffer;
 const Feature = @import("common.zig").Feature;
diff --git a/pkg/harfbuzz/version.zig b/pkg/harfbuzz/version.zig
index dbe25b522..5546ca377 100644
--- a/pkg/harfbuzz/version.zig
+++ b/pkg/harfbuzz/version.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const c = @import("c.zig").c;
+const c = @import("hb_c");
 
 pub const Version = struct {
     major: u32,
diff --git a/pkg/highway/build.zig b/pkg/highway/build.zig
index a02447285..fce823bf3 100644
--- a/pkg/highway/build.zig
+++ b/pkg/highway/build.zig
@@ -18,17 +18,16 @@ pub fn build(b: *std.Build) !void {
             .root_source_file = b.path("src/detect.zig"),
             .target = target,
             .optimize = optimize,
+            // Our highway package is free of libc at runtime (uses no symbols)
+            // but does require libc headers at compile time.
+            .link_libc = true,
         }),
         .linkage = .static,
     });
 
-    // Our highway package is free of libc at runtime (uses no symbols)
-    // but does require libc headers at compile time.
-    lib.linkLibC();
-
-    lib.addIncludePath(b.path("src/cpp"));
+    lib.root_module.addIncludePath(b.path("src/cpp"));
     if (upstream_) |upstream| {
-        lib.addIncludePath(upstream.path(""));
+        lib.root_module.addIncludePath(upstream.path(""));
         module.addIncludePath(upstream.path(""));
     }
 
@@ -102,7 +101,7 @@ pub fn build(b: *std.Build) !void {
         });
     }
 
-    lib.addCSourceFiles(.{ .flags = flags.items, .files = &.{
+    lib.root_module.addCSourceFiles(.{ .flags = flags.items, .files = &.{
         "src/cpp/abort.cc",
         "src/cpp/per_target.cc",
         "src/cpp/targets.cpp",
@@ -127,7 +126,7 @@ pub fn build(b: *std.Build) !void {
                 .optimize = optimize,
             }),
         });
-        test_exe.linkLibrary(lib);
+        test_exe.root_module.linkLibrary(lib);
 
         var it = module.import_table.iterator();
         while (it.next()) |entry| test_exe.root_module.addImport(entry.key_ptr.*, entry.value_ptr.*);
diff --git a/pkg/libintl/build.zig b/pkg/libintl/build.zig
index 32221e5ad..8ef26c7a4 100644
--- a/pkg/libintl/build.zig
+++ b/pkg/libintl/build.zig
@@ -35,11 +35,11 @@ pub fn build(b: *std.Build) !void {
             .root_module = b.createModule(.{
                 .target = target,
                 .optimize = optimize,
+                .link_libc = true,
             }),
             .linkage = .static,
         });
-        lib.linkLibC();
-        lib.addIncludePath(b.path(""));
+        lib.root_module.addIncludePath(b.path(""));
 
         if (target.result.os.tag.isDarwin()) {
             const apple_sdk = @import("apple_sdk");
@@ -47,9 +47,9 @@ pub fn build(b: *std.Build) !void {
         }
 
         if (b.lazyDependency("gettext", .{})) |upstream| {
-            lib.addIncludePath(upstream.path("gettext-runtime/intl"));
-            lib.addIncludePath(upstream.path("gettext-runtime/intl/gnulib-lib"));
-            lib.addCSourceFiles(.{
+            lib.root_module.addIncludePath(upstream.path("gettext-runtime/intl"));
+            lib.root_module.addIncludePath(upstream.path("gettext-runtime/intl/gnulib-lib"));
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path("gettext-runtime/intl"),
                 .files = srcs,
                 .flags = flags.items,
diff --git a/pkg/libpng/build.zig b/pkg/libpng/build.zig
index 8734b28f9..559f42a06 100644
--- a/pkg/libpng/build.zig
+++ b/pkg/libpng/build.zig
@@ -9,18 +9,10 @@ pub fn build(b: *std.Build) !void {
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
-    if (target.result.os.tag == .linux) {
-        lib.linkSystemLibrary("m");
-    }
-    if (target.result.os.tag.isDarwin()) {
-        const apple_sdk = @import("apple_sdk");
-        try apple_sdk.addPaths(b, lib);
-    }
-
     // For dynamic linking, we prefer dynamic linking and to search by
     // mode first. Mode first will search all paths for a dynamic library
     // before falling back to static.
@@ -28,20 +20,27 @@ pub fn build(b: *std.Build) !void {
         .preferred_link_mode = .dynamic,
         .search_strategy = .mode_first,
     };
+    if (target.result.os.tag == .linux) {
+        lib.root_module.linkSystemLibrary("m", dynamic_link_opts);
+    }
+    if (target.result.os.tag.isDarwin()) {
+        const apple_sdk = @import("apple_sdk");
+        try apple_sdk.addPaths(b, lib);
+    }
 
     if (b.systemIntegrationOption("zlib", .{})) {
-        lib.linkSystemLibrary2("zlib", dynamic_link_opts);
+        lib.root_module.linkSystemLibrary("zlib", dynamic_link_opts);
     } else {
         if (b.lazyDependency(
             "zlib",
             .{ .target = target, .optimize = optimize },
         )) |zlib_dep| {
-            lib.linkLibrary(zlib_dep.artifact("z"));
-            lib.addIncludePath(b.path(""));
+            lib.root_module.linkLibrary(zlib_dep.artifact("z"));
+            lib.root_module.addIncludePath(b.path(""));
         }
 
         if (b.lazyDependency("libpng", .{})) |upstream| {
-            lib.addIncludePath(upstream.path(""));
+            lib.root_module.addIncludePath(upstream.path(""));
         }
     }
 
@@ -61,7 +60,7 @@ pub fn build(b: *std.Build) !void {
             });
         }
 
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = srcs,
             .flags = flags.items,
diff --git a/pkg/libxml2/build.zig b/pkg/libxml2/build.zig
index a9b3e4b1a..07a45e947 100644
--- a/pkg/libxml2/build.zig
+++ b/pkg/libxml2/build.zig
@@ -11,18 +11,25 @@ pub fn build(b: *std.Build) !void {
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
 
-    if (upstream_) |upstream| lib.addIncludePath(upstream.path("include"));
-    lib.addIncludePath(b.path("override/include"));
+    if (upstream_) |upstream| lib.root_module.addIncludePath(upstream.path("include"));
+    lib.root_module.addIncludePath(b.path("override/include"));
     if (target.result.os.tag == .windows) {
-        lib.addIncludePath(b.path("override/config/win32"));
-        lib.linkSystemLibrary("ws2_32");
+        lib.root_module.addIncludePath(b.path("override/config/win32"));
+        // For dynamic linking, we prefer dynamic linking and to search by
+        // mode first. Mode first will search all paths for a dynamic library
+        // before falling back to static.
+        const dynamic_link_opts: std.Build.Module.LinkSystemLibraryOptions = .{
+            .preferred_link_mode = .dynamic,
+            .search_strategy = .mode_first,
+        };
+        lib.root_module.linkSystemLibrary("ws2_32", dynamic_link_opts);
     } else {
-        lib.addIncludePath(b.path("override/config/posix"));
+        lib.root_module.addIncludePath(b.path("override/config/posix"));
     }
 
     var flags: std.ArrayList([]const u8) = .empty;
@@ -98,7 +105,7 @@ pub fn build(b: *std.Build) !void {
     }
 
     if (upstream_) |upstream| {
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = srcs,
             .flags = flags.items,
diff --git a/pkg/macos/build.zig b/pkg/macos/build.zig
index 0525e481e..5569baad0 100644
--- a/pkg/macos/build.zig
+++ b/pkg/macos/build.zig
@@ -2,6 +2,66 @@ const std = @import("std");
 const builtin = @import("builtin");
 const apple_sdk = @import("apple_sdk");
 
+const Framework = struct {
+    const Tag = enum { all, macos };
+
+    tag: Tag,
+    name: []const u8,
+    headers: []const []const u8,
+};
+
+const frameworks = [_]Framework{
+    .{ .tag = .all, .name = "CoreFoundation", .headers = &.{"CoreFoundation.h"} },
+    .{ .tag = .all, .name = "CoreGraphics", .headers = &.{"CoreGraphics.h"} },
+    .{ .tag = .all, .name = "CoreText", .headers = &.{"CoreText.h"} },
+    .{ .tag = .all, .name = "CoreVideo", .headers = &.{ "CoreVideo.h", "CVPixelBuffer.h" } },
+    .{ .tag = .all, .name = "QuartzCore", .headers = &.{"CALayer.h"} },
+    .{ .tag = .all, .name = "IOSurface", .headers = &.{"IOSurfaceRef.h"} },
+    .{ .tag = .macos, .name = "Carbon", .headers = &.{"Carbon.h"} },
+};
+
+const extra_headers = [_][]const u8{
+    "dispatch/dispatch.h",
+    "os/log.h",
+    "os/signpost.h",
+};
+
+const framework_header_fmt = "#include <{s}/{s}>\n";
+const extra_header_fmt = "#include <{s}>\n";
+
+fn cSourceLen(tag: Framework.Tag) usize {
+    var len: usize = 0;
+    for (frameworks) |framework| {
+        if (tag != .macos and framework.tag == .macos) continue;
+        for (framework.headers) |h| len += std.fmt.count(framework_header_fmt, .{ framework.name, h });
+    }
+    for (extra_headers) |h| len += std.fmt.count(extra_header_fmt, .{h});
+    return len;
+}
+
+fn genCSource(comptime tag: Framework.Tag) [cSourceLen(tag):0]u8 {
+    const len = cSourceLen(tag);
+    var buf: [len:0]u8 = undefined;
+    var writer: std.Io.Writer = .fixed(&buf);
+    for (frameworks) |framework| {
+        if (tag != .macos and framework.tag == .macos) continue;
+        for (framework.headers) |h| writer.print(framework_header_fmt, .{ framework.name, h }) catch unreachable;
+    }
+    for (extra_headers) |h| writer.print(extra_header_fmt, .{h}) catch unreachable;
+    buf[len] = 0;
+    return buf;
+}
+
+const c_source_macos = genCSource(.macos);
+const c_source_other = genCSource(.all);
+
+fn linkFrameworks(tag: Framework.Tag, module: *std.Build.Module) !void {
+    for (frameworks) |framework| {
+        if (tag != .macos and framework.tag == .macos) continue;
+        module.linkFramework(framework.name, .{});
+    }
+}
+
 pub fn build(b: *std.Build) !void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
@@ -12,6 +72,29 @@ pub fn build(b: *std.Build) !void {
         .optimize = optimize,
     });
 
+    translate: {
+        const translate_c = b.lazyImport(@This(), "translate_c") orelse break :translate;
+        const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse break :translate;
+        const macos_c: translate_c.Translator = .init(translate_c_dep, .{
+            .c_source_file = b.addWriteFiles().add(
+                "macos_c.h",
+                if (target.result.os.tag == .macos) &c_source_macos else &c_source_other,
+            ),
+            .target = target,
+            .optimize = optimize,
+            .libc_file = if (target.result.os.tag.isDarwin()) libc_file: {
+                switch (try apple_sdk.pathsForTarget(b, target.result)) {
+                    inline else => |paths| break :libc_file paths.libc,
+                }
+            } else null,
+        });
+
+        // Blocks need to be enabled to use MacOS headers
+        macos_c.run.addArg("-fblocks");
+
+        module.addImport("macos_c", macos_c.mod);
+    }
+
     const lib = b.addLibrary(.{
         .name = "macos",
         .root_module = b.createModule(.{
@@ -21,34 +104,18 @@ pub fn build(b: *std.Build) !void {
         .linkage = .static,
     });
 
-    lib.addCSourceFile(.{
+    lib.root_module.addCSourceFile(.{
         .file = b.path("os/zig_macos.c"),
         .flags = &.{"-std=c99"},
     });
-    lib.addCSourceFile(.{
+    lib.root_module.addCSourceFile(.{
         .file = b.path("text/ext.c"),
     });
-    lib.linkFramework("CoreFoundation");
-    lib.linkFramework("CoreGraphics");
-    lib.linkFramework("CoreText");
-    lib.linkFramework("CoreVideo");
-    lib.linkFramework("QuartzCore");
-    lib.linkFramework("IOSurface");
-    if (target.result.os.tag == .macos) {
-        lib.linkFramework("Carbon");
-        module.linkFramework("Carbon", .{});
-    }
 
-    if (target.result.os.tag.isDarwin()) {
-        module.linkFramework("CoreFoundation", .{});
-        module.linkFramework("CoreGraphics", .{});
-        module.linkFramework("CoreText", .{});
-        module.linkFramework("CoreVideo", .{});
-        module.linkFramework("QuartzCore", .{});
-        module.linkFramework("IOSurface", .{});
-
-        try apple_sdk.addPaths(b, lib);
+    inline for (.{ lib.root_module, module }) |mod| {
+        try linkFrameworks(if (target.result.os.tag == .macos) .macos else .all, mod);
     }
+    try apple_sdk.addPaths(b, lib);
     b.installArtifact(lib);
 
     {
@@ -63,7 +130,7 @@ pub fn build(b: *std.Build) !void {
         if (target.result.os.tag.isDarwin()) {
             try apple_sdk.addPaths(b, test_exe);
         }
-        test_exe.linkLibrary(lib);
+        test_exe.root_module.linkLibrary(lib);
 
         var it = module.import_table.iterator();
         while (it.next()) |entry| {
diff --git a/pkg/macos/build.zig.zon b/pkg/macos/build.zig.zon
index 4c22ad7c1..58b008c33 100644
--- a/pkg/macos/build.zig.zon
+++ b/pkg/macos/build.zig.zon
@@ -5,5 +5,10 @@
     .paths = .{""},
     .dependencies = .{
         .apple_sdk = .{ .path = "../apple-sdk" },
+        .translate_c = .{
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
+            .lazy = true,
+        },
     },
 }
diff --git a/pkg/macos/main.zig b/pkg/macos/main.zig
index e4f4b9504..68d615672 100644
--- a/pkg/macos/main.zig
+++ b/pkg/macos/main.zig
@@ -10,25 +10,7 @@ pub const text = @import("text.zig");
 pub const video = @import("video.zig");
 pub const iosurface = @import("iosurface.zig");
 
-// All of our C imports consolidated into one place. We used to
-// import them one by one in each package but Zig 0.14 has some
-// kind of issue with that I wasn't able to minimize.
-pub const c = @cImport({
-    @cInclude("CoreFoundation/CoreFoundation.h");
-    @cInclude("CoreGraphics/CoreGraphics.h");
-    @cInclude("CoreText/CoreText.h");
-    @cInclude("CoreVideo/CoreVideo.h");
-    @cInclude("CoreVideo/CVPixelBuffer.h");
-    @cInclude("QuartzCore/CALayer.h");
-    @cInclude("IOSurface/IOSurfaceRef.h");
-    @cInclude("dispatch/dispatch.h");
-    @cInclude("os/log.h");
-    @cInclude("os/signpost.h");
-
-    if (builtin.os.tag == .macos) {
-        @cInclude("Carbon/Carbon.h");
-    }
-});
+pub const c = @import("macos_c");
 
 test {
     @import("std").testing.refAllDecls(@This());
diff --git a/pkg/oniguruma/build.zig b/pkg/oniguruma/build.zig
index d142e5eb1..f7df86e1b 100644
--- a/pkg/oniguruma/build.zig
+++ b/pkg/oniguruma/build.zig
@@ -41,7 +41,7 @@ pub fn build(b: *std.Build) !void {
         module.linkSystemLibrary("oniguruma", dynamic_link_opts);
 
         if (test_exe) |exe| {
-            exe.linkSystemLibrary2("oniguruma", dynamic_link_opts);
+            exe.root_module.linkSystemLibrary("oniguruma", dynamic_link_opts);
         }
     } else {
         const lib = try buildLib(b, module, .{
@@ -50,7 +50,7 @@ pub fn build(b: *std.Build) !void {
         });
 
         if (test_exe) |exe| {
-            exe.linkLibrary(lib);
+            exe.root_module.linkLibrary(lib);
         }
     }
 }
@@ -64,12 +64,12 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
         .linkage = .static,
     });
     const t = target.result;
     const is_windows = t.os.tag == .windows;
-    lib.linkLibC();
 
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
@@ -77,10 +77,10 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
     }
 
     if (b.lazyDependency("oniguruma", .{})) |upstream| {
-        lib.addIncludePath(upstream.path("src"));
+        lib.root_module.addIncludePath(upstream.path("src"));
         module.addIncludePath(upstream.path("src"));
 
-        lib.addConfigHeader(b.addConfigHeader(.{
+        lib.root_module.addConfigHeader(b.addConfigHeader(.{
             .style = .{ .cmake = upstream.path("src/config.h.cmake.in") },
         }, .{
             .PACKAGE = "oniguruma",
@@ -109,7 +109,7 @@ fn buildLib(b: *std.Build, module: *std.Build.Module, options: anytype) !*std.Bu
                 "-fno-sanitize-trap=undefined",
             });
         }
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .flags = flags.items,
             .files = &.{
diff --git a/pkg/sentry/build.zig b/pkg/sentry/build.zig
index 3c88df56d..7eb755f65 100644
--- a/pkg/sentry/build.zig
+++ b/pkg/sentry/build.zig
@@ -17,10 +17,10 @@ pub fn build(b: *std.Build) !void {
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
         try apple_sdk.addPaths(b, lib);
@@ -46,9 +46,9 @@ pub fn build(b: *std.Build) !void {
 
     if (b.lazyDependency("sentry", .{})) |upstream| {
         module.addIncludePath(upstream.path("include"));
-        lib.addIncludePath(upstream.path("include"));
-        lib.addIncludePath(upstream.path("src"));
-        lib.addCSourceFiles(.{
+        lib.root_module.addIncludePath(upstream.path("include"));
+        lib.root_module.addIncludePath(upstream.path("src"));
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = srcs,
             .flags = flags.items,
@@ -56,7 +56,7 @@ pub fn build(b: *std.Build) !void {
 
         // Linux-only
         if (target.result.os.tag == .linux) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "vendor/stb_sprintf.c",
@@ -67,7 +67,7 @@ pub fn build(b: *std.Build) !void {
 
         // Symbolizer + Unwinder
         if (target.result.os.tag == .windows) {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/sentry_windows_dbghelp.c",
@@ -78,7 +78,7 @@ pub fn build(b: *std.Build) !void {
                 .flags = flags.items,
             });
         } else {
-            lib.addCSourceFiles(.{
+            lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/sentry_unix_pageallocator.c",
@@ -92,7 +92,7 @@ pub fn build(b: *std.Build) !void {
 
         // Module finder
         switch (target.result.os.tag) {
-            .windows => lib.addCSourceFiles(.{
+            .windows => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/modulefinder/sentry_modulefinder_windows.c",
@@ -100,7 +100,7 @@ pub fn build(b: *std.Build) !void {
                 .flags = flags.items,
             }),
 
-            .macos, .ios => lib.addCSourceFiles(.{
+            .macos, .ios => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/modulefinder/sentry_modulefinder_apple.c",
@@ -108,7 +108,7 @@ pub fn build(b: *std.Build) !void {
                 .flags = flags.items,
             }),
 
-            .linux => lib.addCSourceFiles(.{
+            .linux => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/modulefinder/sentry_modulefinder_linux.c",
@@ -126,7 +126,7 @@ pub fn build(b: *std.Build) !void {
 
         // Transport
         switch (transport) {
-            .curl => lib.addCSourceFiles(.{
+            .curl => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/transports/sentry_transport_curl.c",
@@ -134,7 +134,7 @@ pub fn build(b: *std.Build) !void {
                 .flags = flags.items,
             }),
 
-            .winhttp => lib.addCSourceFiles(.{
+            .winhttp => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/transports/sentry_transport_winhttp.c",
@@ -142,7 +142,7 @@ pub fn build(b: *std.Build) !void {
                 .flags = flags.items,
             }),
 
-            .none => lib.addCSourceFiles(.{
+            .none => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/transports/sentry_transport_none.c",
@@ -153,7 +153,7 @@ pub fn build(b: *std.Build) !void {
 
         // Backend
         switch (backend) {
-            .crashpad => lib.addCSourceFiles(.{
+            .crashpad => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/backends/sentry_backend_crashpad.cpp",
@@ -162,7 +162,7 @@ pub fn build(b: *std.Build) !void {
             }),
 
             .breakpad => {
-                lib.addCSourceFiles(.{
+                lib.root_module.addCSourceFiles(.{
                     .root = upstream.path(""),
                     .files = &.{
                         "src/backends/sentry_backend_breakpad.cpp",
@@ -174,15 +174,15 @@ pub fn build(b: *std.Build) !void {
                     .target = target,
                     .optimize = optimize,
                 })) |breakpad_dep| {
-                    lib.linkLibrary(breakpad_dep.artifact("breakpad"));
+                    lib.root_module.linkLibrary(breakpad_dep.artifact("breakpad"));
 
                     // We need to add this because Sentry includes some breakpad
                     // headers that include this vendored file...
-                    lib.addIncludePath(breakpad_dep.path("vendor"));
+                    lib.root_module.addIncludePath(breakpad_dep.path("vendor"));
                 }
             },
 
-            .inproc => lib.addCSourceFiles(.{
+            .inproc => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/backends/sentry_backend_inproc.c",
@@ -190,7 +190,7 @@ pub fn build(b: *std.Build) !void {
                 .flags = flags.items,
             }),
 
-            .none => lib.addCSourceFiles(.{
+            .none => lib.root_module.addCSourceFiles(.{
                 .root = upstream.path(""),
                 .files = &.{
                     "src/backends/sentry_backend_none.c",
diff --git a/pkg/simdutf/build.zig b/pkg/simdutf/build.zig
index 0859edc26..a92fa3a07 100644
--- a/pkg/simdutf/build.zig
+++ b/pkg/simdutf/build.zig
@@ -10,26 +10,21 @@ pub fn build(b: *std.Build) !void {
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
+            // We link libcpp even with no_libcxx because simdutf requires
+            // libc++ headers at build time. But it doesn't require libc++ at
+            // runtime. For Ghostty itself, we have CI tests to verify this.
+            //
+            // On MSVC, we must not use linkLibCpp because Zig unconditionally
+            // passes -nostdinc++ and then adds its bundled libc++/libc++abi
+            // include paths, which conflict with MSVC's own C++ runtime
+            // headers. The MSVC SDK include directories (added via linkLibC)
+            // contain both C and C++ headers, so linkLibCpp is not needed.
+            .link_libcpp = target.result.abi != .msvc,
         }),
         .linkage = .static,
     });
-    lib.addIncludePath(b.path("vendor"));
-    lib.linkLibC();
-    libcpp: {
-        if (target.result.abi == .msvc) {
-            // On MSVC, we must not use linkLibCpp because Zig unconditionally
-            // passes -nostdinc++ and then adds its bundled libc++/libc++abi
-            // include paths, which conflict with MSVC's own C++ runtime headers.
-            // The MSVC SDK include directories (added via linkLibC) contain
-            // both C and C++ headers, so linkLibCpp is not needed.
-            break :libcpp;
-        }
-
-        // We link libcpp even with no_libcxx because simdutf requires
-        // libc++ headers at build time. But it doesn't require libc++
-        // at runtime. For Ghostty itself, we have CI tests to verify this.
-        lib.linkLibCpp();
-    }
+    lib.root_module.addIncludePath(b.path("vendor"));
 
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
@@ -70,11 +65,15 @@ pub fn build(b: *std.Build) !void {
         try flags.append(b.allocator, "-std=c++17");
     }
 
-    if (target.result.os.tag == .freebsd or target.result.abi == .musl) {
+    if (target.result.os.tag == .freebsd or
+        target.result.abi == .musl or
+        target.result.abi == .android or
+        target.result.abi == .androideabi)
+    {
         try flags.append(b.allocator, "-fPIC");
     }
 
-    lib.addCSourceFiles(.{
+    lib.root_module.addCSourceFiles(.{
         .flags = flags.items,
         .files = &.{
             "vendor/simdutf.cpp",
diff --git a/pkg/spirv-cross/build.zig b/pkg/spirv-cross/build.zig
index 72ce61eb6..3b85e8f49 100644
--- a/pkg/spirv-cross/build.zig
+++ b/pkg/spirv-cross/build.zig
@@ -34,12 +34,12 @@ pub fn build(b: *std.Build) !void {
     if (b.systemIntegrationOption("spirv-cross", .{})) {
         module.linkSystemLibrary("spirv-cross-c-shared", dynamic_link_opts);
         if (test_exe) |exe| {
-            exe.linkSystemLibrary2("spirv-cross-c-shared", dynamic_link_opts);
+            exe.root_module.linkSystemLibrary("spirv-cross-c-shared", dynamic_link_opts);
         }
     } else {
         const lib = try buildSpirvCross(b, module, target, optimize);
         b.installArtifact(lib);
-        if (test_exe) |exe| exe.linkLibrary(lib);
+        if (test_exe) |exe| exe.root_module.linkLibrary(lib);
     }
 }
 
@@ -54,18 +54,16 @@ fn buildSpirvCross(
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
+            // On MSVC, we must not use linkLibCpp because Zig unconditionally
+            // passes -nostdinc++ and then adds its bundled libc++/libc++abi
+            // include paths, which conflict with MSVC's own C++ runtime
+            // headers. The MSVC SDK include directories (added via linkLibC)
+            // contain both C and C++ headers, so linkLibCpp is not needed.
+            .link_libcpp = target.result.abi != .msvc,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
-    // On MSVC, we must not use linkLibCpp because Zig unconditionally
-    // passes -nostdinc++ and then adds its bundled libc++/libc++abi
-    // include paths, which conflict with MSVC's own C++ runtime headers.
-    // The MSVC SDK include directories (added via linkLibC) contain
-    // both C and C++ headers, so linkLibCpp is not needed.
-    if (target.result.abi != .msvc) {
-        lib.linkLibCpp();
-    }
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
         try apple_sdk.addPaths(b, lib);
@@ -86,9 +84,9 @@ fn buildSpirvCross(
     }
 
     if (b.lazyDependency("spirv_cross", .{})) |upstream| {
-        lib.addIncludePath(upstream.path(""));
+        lib.root_module.addIncludePath(upstream.path(""));
         module.addIncludePath(upstream.path(""));
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .flags = flags.items,
             .files = &.{
diff --git a/pkg/wuffs/build.zig b/pkg/wuffs/build.zig
index 95cef3e09..b90c7e9fb 100644
--- a/pkg/wuffs/build.zig
+++ b/pkg/wuffs/build.zig
@@ -1,5 +1,38 @@
 const std = @import("std");
 
+// All the C macros defined so that the header matches the build.
+const defines = [_][]const u8{
+    "WUFFS_CONFIG__MODULES",
+    "WUFFS_CONFIG__MODULE__AUX__BASE",
+    "WUFFS_CONFIG__MODULE__AUX__IMAGE",
+    "WUFFS_CONFIG__MODULE__BASE",
+    "WUFFS_CONFIG__MODULE__ADLER32",
+    "WUFFS_CONFIG__MODULE__CRC32",
+    "WUFFS_CONFIG__MODULE__DEFLATE",
+    "WUFFS_CONFIG__MODULE__JPEG",
+    "WUFFS_CONFIG__MODULE__PNG",
+    "WUFFS_CONFIG__MODULE__ZLIB",
+};
+
+// Generated C code, includes the macros above. Designed to mimic old c.zig.
+// TODO: is this still needed, or are the -D flags enough?
+const wuffs_c_source = wuffs_c_source: {
+    const include: []const u8 = "#include <wuffs-v0.4.c>";
+    const len = len: {
+        var len: usize = 0;
+        for (defines) |d| len += std.fmt.count("#define {s}\n", .{d});
+        len += std.fmt.count("{s}\n", .{include});
+        break :len len;
+    };
+
+    var buf: [len:0]u8 = undefined;
+    var writer: std.Io.Writer = .fixed(&buf);
+    for (defines) |d| writer.print("#define {s}\n", .{d}) catch unreachable;
+    writer.print("{s}\n", .{include}) catch unreachable;
+    buf[len] = 0;
+    break :wuffs_c_source buf;
+};
+
 pub fn build(b: *std.Build) !void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
@@ -15,25 +48,41 @@ pub fn build(b: *std.Build) !void {
         .name = "test",
         .root_module = module,
     });
-    unit_tests.linkLibC();
 
-    var flags: std.ArrayList([]const u8) = .empty;
-    defer flags.deinit(b.allocator);
-    try flags.append(b.allocator, "-DWUFFS_IMPLEMENTATION");
-    if (target.result.abi == .msvc) {
-        try flags.append(b.allocator, "-fno-sanitize=undefined");
-        try flags.append(b.allocator, "-fno-sanitize-trap=undefined");
-    }
-    inline for (@import("src/c.zig").defines) |key| {
-        try flags.append(b.allocator, "-D" ++ key);
-    }
-
-    if (b.lazyDependency("wuffs", .{})) |wuffs_dep| {
-        module.addIncludePath(wuffs_dep.path("release/c"));
-        module.addCSourceFile(.{
-            .file = wuffs_dep.path("release/c/wuffs-v0.4.c"),
-            .flags = flags.items,
+    translate: {
+        const translate_c = b.lazyImport(@This(), "translate_c") orelse break :translate;
+        const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse break :translate;
+        const wuffs_c: translate_c.Translator = .init(translate_c_dep, .{
+            .c_source_file = b.addWriteFiles().add("wuffs_c.h", &wuffs_c_source),
+            .target = target,
+            .optimize = optimize,
+            .libc_file = if (target.result.os.tag.isDarwin()) libc_file: {
+                switch (try @import("apple_sdk").pathsForTarget(b, target.result)) {
+                    inline else => |paths| break :libc_file paths.libc,
+                }
+            } else null,
         });
+
+        var flags: std.ArrayList([]const u8) = .empty;
+        defer flags.deinit(b.allocator);
+        try flags.append(b.allocator, "-DWUFFS_IMPLEMENTATION");
+        if (target.result.abi == .msvc) {
+            try flags.append(b.allocator, "-fno-sanitize=undefined");
+            try flags.append(b.allocator, "-fno-sanitize-trap=undefined");
+        }
+        inline for (defines) |key| {
+            try flags.append(b.allocator, "-D" ++ key);
+        }
+
+        if (b.lazyDependency("wuffs", .{})) |wuffs_dep| {
+            wuffs_c.addIncludePath(wuffs_dep.path("release/c"));
+            wuffs_c.mod.addCSourceFile(.{
+                .file = wuffs_dep.path("release/c/wuffs-v0.4.c"),
+                .flags = flags.items,
+            });
+        }
+
+        module.addImport("wuffs_c", wuffs_c.mod);
     }
 
     if (b.lazyDependency("pixels", .{})) |pixels_dep| {
diff --git a/pkg/wuffs/build.zig.zon b/pkg/wuffs/build.zig.zon
index eb99ba0b0..1cf438e8e 100644
--- a/pkg/wuffs/build.zig.zon
+++ b/pkg/wuffs/build.zig.zon
@@ -3,6 +3,12 @@
     .version = "0.0.0",
     .fingerprint = 0x67c0c059de921c4f,
     .dependencies = .{
+        .translate_c = .{
+            .lazy = true,
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
+        },
+
         // google/wuffs
         .wuffs = .{
             .url = "https://deps.files.ghostty.org/wuffs-122037b39d577ec2db3fd7b2130e7b69ef6cc1807d68607a7c232c958315d381b5cd.tar.gz",
diff --git a/pkg/wuffs/src/c.zig b/pkg/wuffs/src/c.zig
deleted file mode 100644
index d94247df3..000000000
--- a/pkg/wuffs/src/c.zig
+++ /dev/null
@@ -1,18 +0,0 @@
-pub const c = @cImport({
-    for (defines) |d| @cDefine(d, "1");
-    @cInclude("wuffs-v0.4.c");
-});
-
-/// All the C macros defined so that the header matches the build.
-pub const defines: []const []const u8 = &[_][]const u8{
-    "WUFFS_CONFIG__MODULES",
-    "WUFFS_CONFIG__MODULE__AUX__BASE",
-    "WUFFS_CONFIG__MODULE__AUX__IMAGE",
-    "WUFFS_CONFIG__MODULE__BASE",
-    "WUFFS_CONFIG__MODULE__ADLER32",
-    "WUFFS_CONFIG__MODULE__CRC32",
-    "WUFFS_CONFIG__MODULE__DEFLATE",
-    "WUFFS_CONFIG__MODULE__JPEG",
-    "WUFFS_CONFIG__MODULE__PNG",
-    "WUFFS_CONFIG__MODULE__ZLIB",
-};
diff --git a/pkg/wuffs/src/error.zig b/pkg/wuffs/src/error.zig
index 0be55cf4e..e4ca5c1da 100644
--- a/pkg/wuffs/src/error.zig
+++ b/pkg/wuffs/src/error.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 
-const c = @import("c.zig").c;
+const c = @import("wuffs_c");
 
 pub const Error = std.mem.Allocator.Error || error{ WuffsError, Overflow };
 
diff --git a/pkg/wuffs/src/jpeg.zig b/pkg/wuffs/src/jpeg.zig
index 69d91c8a9..a7bc4bdd2 100644
--- a/pkg/wuffs/src/jpeg.zig
+++ b/pkg/wuffs/src/jpeg.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
-const c = @import("c.zig").c;
+const c = @import("wuffs_c");
 const Error = @import("error.zig").Error;
 const check = @import("error.zig").check;
 const ImageData = @import("main.zig").ImageData;
diff --git a/pkg/wuffs/src/main.zig b/pkg/wuffs/src/main.zig
index 207d83f9a..b4519a983 100644
--- a/pkg/wuffs/src/main.zig
+++ b/pkg/wuffs/src/main.zig
@@ -1,3 +1,4 @@
+const builtin = @import("builtin");
 const std = @import("std");
 
 pub const png = @import("png.zig");
@@ -16,5 +17,19 @@ pub const ImageData = struct {
 };
 
 test {
-    std.testing.refAllDeclsRecursive(@This());
+    refAllDeclsRecursive(@This());
+}
+
+/// Copied from 0.15.2 stdlib (MIT license).
+fn refAllDeclsRecursive(comptime T: type) void {
+    if (!builtin.is_test) return;
+    inline for (comptime std.meta.declarations(T)) |decl| {
+        if (@TypeOf(@field(T, decl.name)) == type) {
+            switch (@typeInfo(@field(T, decl.name))) {
+                .@"struct", .@"enum", .@"union", .@"opaque" => refAllDeclsRecursive(@field(T, decl.name)),
+                else => {},
+            }
+        }
+        _ = &@field(T, decl.name);
+    }
 }
diff --git a/pkg/wuffs/src/png.zig b/pkg/wuffs/src/png.zig
index 57a0e63bb..4bf3d759c 100644
--- a/pkg/wuffs/src/png.zig
+++ b/pkg/wuffs/src/png.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
-const c = @import("c.zig").c;
+const c = @import("wuffs_c");
 const Error = @import("error.zig").Error;
 const check = @import("error.zig").check;
 const ImageData = @import("main.zig").ImageData;
diff --git a/pkg/wuffs/src/swizzle.zig b/pkg/wuffs/src/swizzle.zig
index 352cf2b50..9e7ffa5cb 100644
--- a/pkg/wuffs/src/swizzle.zig
+++ b/pkg/wuffs/src/swizzle.zig
@@ -1,7 +1,7 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
 const assert = std.debug.assert;
-const c = @import("c.zig").c;
+const c = @import("wuffs_c");
 const Error = @import("error.zig").Error;
 
 const log = std.log.scoped(.wuffs_swizzler);
diff --git a/pkg/zlib/build.zig b/pkg/zlib/build.zig
index 64db13aa1..3fa9e6bd2 100644
--- a/pkg/zlib/build.zig
+++ b/pkg/zlib/build.zig
@@ -9,17 +9,17 @@ pub fn build(b: *std.Build) !void {
         .root_module = b.createModule(.{
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
         .linkage = .static,
     });
-    lib.linkLibC();
     if (target.result.os.tag.isDarwin()) {
         const apple_sdk = @import("apple_sdk");
         try apple_sdk.addPaths(b, lib);
     }
 
     if (b.lazyDependency("zlib", .{})) |upstream| {
-        lib.addIncludePath(upstream.path(""));
+        lib.root_module.addIncludePath(upstream.path(""));
         lib.installHeadersDirectory(
             upstream.path(""),
             "",
@@ -48,7 +48,7 @@ pub fn build(b: *std.Build) !void {
                 "-D_CRT_NONSTDC_NO_DEPRECATE",
             });
         }
-        lib.addCSourceFiles(.{
+        lib.root_module.addCSourceFiles(.{
             .root = upstream.path(""),
             .files = srcs,
             .flags = flags.items,
diff --git a/src/App.zig b/src/App.zig
index 93ee7dea1..c87867ea9 100644
--- a/src/App.zig
+++ b/src/App.zig
@@ -15,6 +15,7 @@ const Config = configpkg.Config;
 const BlockingQueue = @import("datastruct/main.zig").BlockingQueue;
 const renderer = @import("renderer.zig");
 const font = @import("font/main.zig");
+const global = @import("global.zig");
 
 const log = std.log.scoped(.app);
 
@@ -56,7 +57,7 @@ font_grid_set: font.SharedGridSet,
 // Used to rate limit desktop notifications. Some platforms (notably macOS) will
 // run out of resources if desktop notifications are sent too fast and the OS
 // will kill Ghostty.
-last_notification_time: ?std.time.Instant = null,
+last_notification_time: ?std.Io.Timestamp = null,
 last_notification_digest: u64 = 0,
 
 /// The conditional state of the configuration. See the equivalent field
@@ -95,7 +96,7 @@ pub fn init(
 
     self.* = .{
         .alloc = alloc,
-        .surfaces = .{},
+        .surfaces = .empty,
         .mailbox = .{},
         .font_grid_set = font_grid_set,
         .config_conditional_state = .{},
@@ -236,7 +237,7 @@ pub fn needsConfirmQuit(self: *const App) bool {
 
 /// Drain the mailbox.
 fn drainMailbox(self: *App, rt_app: *apprt.App) !void {
-    while (self.mailbox.pop()) |message| {
+    while (self.mailbox.pop(global.io())) |message| {
         if (comptime std.log.logEnabled(.debug, .app)) {
             switch (message) {
                 // these tend to be way too verbose for normal debugging
@@ -566,7 +567,7 @@ pub const Mailbox = struct {
 
     /// Send a message to the surface.
     pub fn push(self: Mailbox, msg: Message, timeout: Queue.Timeout) Queue.Size {
-        const result = self.mailbox.push(msg, timeout);
+        const result = self.mailbox.push(global.io(), msg, timeout);
 
         // Wake up our app loop
         self.rt_app.wakeup();
diff --git a/src/Command.zig b/src/Command.zig
index b81936257..3fc498a9a 100644
--- a/src/Command.zig
+++ b/src/Command.zig
@@ -14,12 +14,15 @@
 //!   * posix_spawn is used for Mac, but doesn't support the necessary
 //!     features for tty setup.
 //!
+//!
+//! TODO: This may have changed a lot now with the new I/O implementations in
+//! >= 0.16.0, so this might warrant a recheck.
 const Command = @This();
 
 const std = @import("std");
 const builtin = @import("builtin");
 const configpkg = @import("config.zig");
-const global_state = &@import("global.zig").state;
+const global = @import("global.zig");
 const internal_os = @import("os/main.zig");
 const windows = internal_os.windows;
 const TempDir = internal_os.TempDir;
@@ -29,8 +32,8 @@ const posix = std.posix;
 const debug = std.debug;
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
-const File = std.fs.File;
-const EnvMap = std.process.EnvMap;
+const File = std.Io.File;
+const EnvMap = std.process.Environ.Map;
 const apprt = @import("apprt.zig");
 
 /// Function prototype for a function executed /in the child process/ after the
@@ -65,7 +68,7 @@ env: ?*const EnvMap = null,
 
 /// Working directory to change to in the child process. If not set, the
 /// working directory of the calling process is preserved.
-cwd: ?[]const u8 = null,
+cwd: ?[:0]const u8 = null,
 
 /// The file handle to set for stdin/out/err. If this isn't set, we do
 /// nothing explicitly so it is up to the behavior of the operating system.
@@ -98,7 +101,7 @@ rt_post_fork_info: RtPostForkInfo,
 
 /// If set, then the process will be created attached to this pseudo console.
 /// `stdin`, `stdout`, and `stderr` will be ignored if set.
-pseudo_console: if (builtin.os.tag == .windows) ?windows.exp.HPCON else void =
+pseudo_console: if (builtin.os.tag == .windows) ?windows.HPCON else void =
     if (builtin.os.tag == .windows) null else {},
 
 /// User data that is sent to the callback. Set with setData and getData
@@ -106,7 +109,7 @@ pseudo_console: if (builtin.os.tag == .windows) ?windows.exp.HPCON else void =
 data: ?*anyopaque = null,
 
 /// Process ID is set after start is called.
-pid: ?posix.pid_t = null,
+pid: ?posix.system.pid_t = null,
 
 /// The various methods a process may exit.
 pub const Exit = if (builtin.os.tag == .windows) union(enum) {
@@ -128,9 +131,9 @@ pub const Exit = if (builtin.os.tag == .windows) union(enum) {
         return if (posix.W.IFEXITED(status))
             Exit{ .Exited = posix.W.EXITSTATUS(status) }
         else if (posix.W.IFSIGNALED(status))
-            Exit{ .Signal = posix.W.TERMSIG(status) }
+            Exit{ .Signal = @intFromEnum(posix.W.TERMSIG(status)) }
         else if (posix.W.IFSTOPPED(status))
-            Exit{ .Stopped = posix.W.STOPSIG(status) }
+            Exit{ .Stopped = @intFromEnum(posix.W.STOPSIG(status)) }
         else
             Exit{ .Unknown = status };
     }
@@ -186,7 +189,7 @@ fn startPosix(self: *Command, arena: Allocator) !void {
         @compileError("missing env vars");
 
     // Fork.
-    const pid = try posix.fork();
+    const pid = try fork();
 
     if (pid != 0) {
         // Parent, return immediately.
@@ -205,37 +208,68 @@ fn startPosix(self: *Command, arena: Allocator) !void {
     if (self.stderr) |f| setupFd(f.handle, posix.STDERR_FILENO) catch
         return error.ExecFailedInChild;
 
-    // Setup our working directory
-    if (self.cwd) |cwd| posix.chdir(cwd) catch {
-        // This can fail if we don't have permission to go to
-        // this directory or if due to race conditions it doesn't
-        // exist or any various other reasons. We don't want to
-        // crash the entire process if this fails so we ignore it.
-        // We don't log because that'll show up in the output.
-    };
+    // Setup our working directory.
+    //
+    // NOTE: this can fail if we don't have permission to go to this directory
+    // or if due to race conditions it doesn't exist or any various other
+    // reasons. We don't want to crash the entire process if this fails so we
+    // ignore it. We don't log because that'll show up in the output.
+    if (self.cwd) |cwd| _ = posix.system.chdir(cwd);
 
     // Restore any rlimits that were set by Ghostty. This might fail but
     // any failures are ignored (its best effort).
-    global_state.rlimits.restore();
+    global.rlimits().restore();
 
     // If there are pre exec callbacks, call them now.
-    if (self.os_pre_exec) |f| if (f(self)) |exitcode| posix.exit(exitcode);
-    if (self.rt_pre_exec) |f| if (f(self)) |exitcode| posix.exit(exitcode);
+    if (self.os_pre_exec) |f| if (f(self)) |exitcode| posix.system.exit(exitcode);
+    if (self.rt_pre_exec) |f| if (f(self)) |exitcode| posix.system.exit(exitcode);
 
-    // Finally, replace our process.
-    // Note: we must use the "p"-variant of exec here because we
-    // do not guarantee our command is looked up already in the path.
-    const err = posix.execvpeZ(self.path, argsZ, envp);
+    const err: posix.E = execve: {
+        // This functionality has been taken from Zig stdlib, a simplified
+        // version of the exec bits with PATH search so that we can just
+        // offload to execve below.
+        const file_slice = std.mem.sliceTo(self.path, 0);
+        if (std.mem.findScalar(u8, file_slice, '/') != null) {
+            break :execve posix.errno(posix.system.execve(self.path, argsZ, envp));
+        }
+
+        var path_expanded_buf: [std.fs.max_path_bytes]u8 = undefined;
+        const PATH = global.environ().getPosix("PATH") orelse "/usr/local/bin:/bin/:/usr/bin";
+        var it = std.mem.tokenizeScalar(u8, PATH, ':');
+        var err: posix.system.E = .NOENT;
+        var seen_eacces = false;
+
+        while (it.next()) |search_path| {
+            const path_len = search_path.len + file_slice.len + 1;
+            if (path_expanded_buf.len < path_len + 1) break :execve .NAMETOOLONG;
+            @memcpy(path_expanded_buf[0..search_path.len], search_path);
+            path_expanded_buf[search_path.len] = '/';
+            @memcpy(path_expanded_buf[search_path.len + 1 ..][0..file_slice.len], file_slice);
+            path_expanded_buf[path_len] = 0;
+            const full_path = path_expanded_buf[0..path_len :0].ptr;
+            // Replace here, switch on error (any error means that replace
+            // failed, but we might need to retry).
+            err = posix.errno(posix.system.execve(full_path, argsZ, envp));
+            switch (err) {
+                .ACCES => seen_eacces = true,
+                .NOENT, .NOTDIR => {},
+                else => break :execve err,
+            }
+        }
+
+        if (seen_eacces) break :execve .ACCES;
+        break :execve err;
+    };
 
     // If we are executing this code, the exec failed. We're in the
     // child process so there isn't much we can do. We try to output
     // something reasonable. Its important to note we MUST NOT return
     // any other error condition from here on out.
     var stderr_buf: [1024]u8 = undefined;
-    var stderr_writer = std.fs.File.stderr().writer(&stderr_buf);
+    var stderr_writer = std.Io.File.stderr().writer(global.io(), &stderr_buf);
     const stderr = &stderr_writer.interface;
     switch (err) {
-        error.FileNotFound => stderr.print(
+        posix.system.E.NOENT => stderr.print(
             \\Requested executable not found. Please verify the command is on
             \\the PATH and try again.
             \\
@@ -243,11 +277,11 @@ fn startPosix(self: *Command, arena: Allocator) !void {
             .{},
         ) catch {},
 
-        else => stderr.print(
-            \\exec syscall failed with unexpected error: {}
+        else => |e| stderr.print(
+            \\exec syscall failed with unexpected error: E{s}
             \\
         ,
-            .{err},
+            .{@tagName(e)},
         ) catch {},
     }
     stderr.flush() catch {};
@@ -257,6 +291,17 @@ fn startPosix(self: *Command, arena: Allocator) !void {
     return error.ExecFailedInChild;
 }
 
+/// Wrapper for the raw fork syscall. This preserves the error handling from
+/// the std.posix wrapper that was removed in Zig 0.16.
+fn fork() !posix.pid_t {
+    const rc = posix.system.fork();
+    switch (posix.errno(rc)) {
+        .SUCCESS => return @intCast(rc),
+        .AGAIN, .NOMEM => return error.SystemResources,
+        else => |err| return posix.unexpectedErrno(err),
+    }
+}
+
 fn startWindows(self: *Command, arena: Allocator) !void {
     const cwd_w = if (self.cwd) |cwd| try std.unicode.utf8ToUtf16LeAllocZ(arena, cwd) else null;
 
@@ -275,15 +320,37 @@ fn startWindows(self: *Command, arena: Allocator) !void {
     const env_w = if (self.env) |env_map| try createWindowsEnvBlock(arena, env_map) else null;
 
     const any_null_fd = self.stdin == null or self.stdout == null or self.stderr == null;
-    const null_fd = if (any_null_fd) try windows.OpenFile(
-        &[_]u16{ '\\', 'D', 'e', 'v', 'i', 'c', 'e', '\\', 'N', 'u', 'l', 'l' },
-        .{
-            .access_mask = windows.GENERIC_READ | windows.SYNCHRONIZE,
-            .share_access = windows.FILE_SHARE_READ,
-            .creation = windows.OPEN_EXISTING,
-        },
-    ) else null;
-    defer if (null_fd) |fd| posix.close(fd);
+    const null_fd = if (any_null_fd) null_fd: {
+        // path = "\Device\Null"
+        const path = [_]u16{ '\\', 'D', 'e', 'v', 'i', 'c', 'e', '\\', 'N', 'u', 'l', 'l' };
+        var path_unicode_string: windows.UNICODE_STRING = .init(&path);
+        var attrs: windows.OBJECT_ATTRIBUTES = .{ .ObjectName = &path_unicode_string };
+
+        var fd: windows.HANDLE = undefined;
+        var io_status: windows.IO_STATUS_BLOCK = undefined; // unused
+        const result = windows.exp.ntdll.NtCreateFile(
+            &fd,
+            .{ .GENERIC = .{ .READ = true }, .STANDARD = .{ .SYNCHRONIZE = true } },
+            &attrs,
+            &io_status,
+            null,
+            windows.FILE_ATTRIBUTE_NORMAL,
+            windows.FILE_SHARE_READ,
+            windows.OPEN_EXISTING,
+            windows.FILE_NON_DIRECTORY_FILE,
+            null,
+            0,
+        );
+
+        if (result != .SUCCESS) {
+            return windows.unexpectedStatus(result);
+        }
+
+        break :null_fd fd;
+    } else null;
+    defer {
+        if (null_fd) |fd| _ = windows.exp.kernel32.CloseHandle(fd);
+    }
 
     // TODO: In the case of having FDs instead of pty, need to set up
     // attributes such that the child process only inherits these handles,
@@ -304,17 +371,17 @@ fn startWindows(self: *Command, arena: Allocator) !void {
             1,
             0,
             &attribute_list_size,
-        ) == 0) return windows.unexpectedError(windows.kernel32.GetLastError());
+        ) == windows.FALSE) return windows.unexpectedError(windows.GetLastError());
 
         if (windows.exp.kernel32.UpdateProcThreadAttribute(
             attribute_list_buf.ptr,
             0,
-            windows.exp.PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE,
+            windows.PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE,
             pseudo_console,
-            @sizeOf(windows.exp.HPCON),
+            @sizeOf(windows.HPCON),
             null,
             null,
-        ) == 0) return windows.unexpectedError(windows.kernel32.GetLastError());
+        ) == windows.FALSE) return windows.unexpectedError(windows.GetLastError());
 
         break :b .{ attribute_list_buf.ptr, null, null, null };
     } else b: {
@@ -324,9 +391,9 @@ fn startWindows(self: *Command, arena: Allocator) !void {
         break :b .{ null, stdin, stdout, stderr };
     };
 
-    var startup_info_ex = windows.exp.STARTUPINFOEX{
+    var startup_info_ex = windows.STARTUPINFOEX{
         .StartupInfo = .{
-            .cb = if (attribute_list != null) @sizeOf(windows.exp.STARTUPINFOEX) else @sizeOf(windows.STARTUPINFOW),
+            .cb = if (attribute_list != null) @sizeOf(windows.STARTUPINFOEX) else @sizeOf(windows.STARTUPINFOW),
             .hStdError = stderr,
             .hStdOutput = stdout,
             .hStdInput = stdin,
@@ -348,8 +415,8 @@ fn startWindows(self: *Command, arena: Allocator) !void {
         .lpAttributeList = attribute_list,
     };
 
-    var flags: windows.DWORD = windows.exp.CREATE_UNICODE_ENVIRONMENT;
-    if (attribute_list != null) flags |= windows.exp.EXTENDED_STARTUPINFO_PRESENT;
+    var flags: windows.DWORD = windows.CREATE_UNICODE_ENVIRONMENT;
+    if (attribute_list != null) flags |= windows.EXTENDED_STARTUPINFO_PRESENT;
 
     var process_information: windows.PROCESS_INFORMATION = undefined;
     if (windows.exp.kernel32.CreateProcessW(
@@ -363,21 +430,18 @@ fn startWindows(self: *Command, arena: Allocator) !void {
         if (cwd_w) |w| w.ptr else null,
         @ptrCast(&startup_info_ex.StartupInfo),
         &process_information,
-    ) == 0) return windows.unexpectedError(windows.kernel32.GetLastError());
+    ) == windows.FALSE) return windows.unexpectedError(windows.GetLastError());
 
     self.pid = process_information.hProcess;
 }
 
 fn setupFd(src: File.Handle, target: i32) !void {
-    switch (builtin.os.tag) {
-        .linux => {
-            // We use dup3 so that we can clear CLO_ON_EXEC. We do NOT want this
-            // file descriptor to be closed on exec since we're exactly exec-ing after
-            // this.
+    const PosixCall = struct {
+        fn f(func: anytype, args: anytype) !usize {
             while (true) {
-                const rc = linux.dup3(src, target, 0);
+                const rc = @call(.auto, func, args);
                 switch (posix.errno(rc)) {
-                    .SUCCESS => break,
+                    .SUCCESS => return @intCast(rc),
                     .INTR => continue,
                     .AGAIN, .ACCES => return error.Locked,
                     .BADF => unreachable,
@@ -391,16 +455,28 @@ fn setupFd(src: File.Handle, target: i32) !void {
                     else => |err| return posix.unexpectedErrno(err),
                 }
             }
+        }
+    };
+
+    switch (builtin.os.tag) {
+        .linux => {
+            // We use dup3 so that we can clear CLO_ON_EXEC. We do NOT want this
+            // file descriptor to be closed on exec since we're exactly exec-ing after
+            // this.
+            _ = try PosixCall.f(linux.dup3, .{ src, target, 0 });
         },
         .freebsd, .ios, .macos => {
             // Mac doesn't support dup3 so we use dup2. We purposely clear
             // CLO_ON_EXEC for this fd.
-            const flags = try posix.fcntl(src, posix.F.GETFD, 0);
+            const flags = try PosixCall.f(posix.system.fcntl, .{ src, posix.F.GETFD });
             if (flags & posix.FD_CLOEXEC != 0) {
-                _ = try posix.fcntl(src, posix.F.SETFD, flags & ~@as(u32, posix.FD_CLOEXEC));
+                _ = try PosixCall.f(
+                    posix.system.fcntl,
+                    .{ src, posix.F.SETFD, flags & ~@as(u32, posix.FD_CLOEXEC) },
+                );
             }
 
-            try posix.dup2(src, target);
+            _ = try PosixCall.f(posix.system.dup2, .{ src, target });
         },
         else => @compileError("unsupported platform"),
     }
@@ -411,21 +487,29 @@ pub fn wait(self: Command, block: bool) !Exit {
     if (comptime builtin.os.tag == .windows) {
         // Block until the process exits. This returns immediately if the
         // process already exited.
-        const result = windows.kernel32.WaitForSingleObject(self.pid.?, windows.INFINITE);
+        //
+        // NOTE: We can use the pid directly as posix.system.pid_t is still an
+        // alias for a handle under Windows. We might want to keep an eye on if
+        // this changes, though.
+        const result = windows.exp.kernel32.WaitForSingleObject(self.pid.?, windows.INFINITE);
         if (result == windows.WAIT_FAILED) {
-            return windows.unexpectedError(windows.kernel32.GetLastError());
+            return windows.unexpectedError(windows.GetLastError());
         }
 
         var exit_code: windows.DWORD = undefined;
-        const has_code = windows.kernel32.GetExitCodeProcess(self.pid.?, &exit_code) != 0;
+        const has_code = windows.exp.kernel32.GetExitCodeProcess(self.pid.?, &exit_code) != windows.FALSE;
         if (!has_code) {
-            return windows.unexpectedError(windows.kernel32.GetLastError());
+            return windows.unexpectedError(windows.GetLastError());
         }
 
         return .{ .Exited = exit_code };
     }
 
-    const res = if (block) posix.waitpid(self.pid.?, 0) else res: {
+    const status: u32 = if (block) wait_block: {
+        var status: if (builtin.link_libc) c_int else u32 = undefined;
+        _ = try waitPid(self.pid.?, &status, 0);
+        break :wait_block @bitCast(status);
+    } else wait_nohang: {
         // We specify NOHANG because its not our fault if the process we launch
         // for the tty doesn't properly waitpid its children. We don't want
         // to hang the terminal over it.
@@ -434,12 +518,32 @@ pub fn wait(self: Command, block: bool) !Exit {
         // wait call has not been performed, so we need to keep trying until we get
         // a non-zero pid back, otherwise we end up with zombie processes.
         while (true) {
-            const res = posix.waitpid(self.pid.?, std.c.W.NOHANG);
-            if (res.pid != 0) break :res res;
+            var status: if (builtin.link_libc) c_int else u32 = undefined;
+            const pid = try waitPid(self.pid.?, &status, posix.system.W.NOHANG);
+            if (pid != 0) break :wait_nohang @bitCast(status);
         }
     };
 
-    return .init(res.status);
+    return .init(status);
+}
+
+/// Wrapper for the raw waitpid syscall. Status is only initialized on success;
+/// interrupted waits are retried and all other errors are propagated.
+fn waitPid(
+    pid: posix.pid_t,
+    status: *if (builtin.link_libc) c_int else u32,
+    flags: u32,
+) !posix.pid_t {
+    while (true) {
+        const rc = posix.system.waitpid(pid, status, @intCast(flags));
+        switch (posix.errno(rc)) {
+            .SUCCESS => return @intCast(rc),
+            .INTR => continue,
+            .CHILD => return error.NoChildProcess,
+            .INVAL => return error.InvalidWaitOptions,
+            else => |err| return posix.unexpectedErrno(err),
+        }
+    }
 }
 
 /// Sets command->data to data.
@@ -587,7 +691,7 @@ test "Command: os pre exec 1" {
             fn do(_: *Command) ?u8 {
                 // This runs in the child, so we can exit and it won't
                 // kill the test runner.
-                posix.exit(42);
+                posix.system.exit(42);
             }
         }).do,
         .rt_pre_exec = null,
@@ -638,7 +742,7 @@ test "Command: rt pre exec 1" {
             fn do(_: *Command) ?u8 {
                 // This runs in the child, so we can exit and it won't
                 // kill the test runner.
-                posix.exit(42);
+                posix.system.exit(42);
             }
         }).do,
         .rt_post_fork = null,
@@ -697,27 +801,31 @@ test "Command: rt post fork 1" {
     try testing.expectError(error.PostForkError, cmd.testingStart());
 }
 
-fn createTestStdout(dir: std.fs.Dir) !File {
-    const file = try dir.createFile("stdout.txt", .{ .read = true });
+fn createTestStdout(io: std.Io, dir: std.Io.Dir) !File {
+    const file = try dir.createFile(io, "stdout.txt", .{ .read = true });
     if (builtin.os.tag == .windows) {
-        try windows.SetHandleInformation(
+        if (windows.exp.kernel32.SetHandleInformation(
             file.handle,
             windows.HANDLE_FLAG_INHERIT,
             windows.HANDLE_FLAG_INHERIT,
-        );
+        ) == windows.FALSE) {
+            return windows.unexpectedError(windows.GetLastError());
+        }
     }
 
     return file;
 }
 
-fn createTestStderr(dir: std.fs.Dir) !File {
-    const file = try dir.createFile("stderr.txt", .{ .read = true });
+fn createTestStderr(io: std.Io, dir: std.Io.Dir) !File {
+    const file = try dir.createFile(io, "stderr.txt", .{ .read = true });
     if (builtin.os.tag == .windows) {
-        try windows.SetHandleInformation(
+        if (windows.exp.kernel32.SetHandleInformation(
             file.handle,
             windows.HANDLE_FLAG_INHERIT,
             windows.HANDLE_FLAG_INHERIT,
-        );
+        ) == windows.FALSE) {
+            return windows.unexpectedError(windows.GetLastError());
+        }
     }
 
     return file;
@@ -726,8 +834,8 @@ fn createTestStderr(dir: std.fs.Dir) !File {
 test "Command: redirect stdout to file" {
     var td = try TempDir.init();
     defer td.deinit();
-    var stdout = try createTestStdout(td.dir);
-    defer stdout.close();
+    var stdout = try createTestStdout(testing.io, td.dir);
+    defer stdout.close(testing.io);
 
     var cmd: Command = if (builtin.os.tag == .windows) .{
         .path = "C:\\Windows\\System32\\whoami.exe",
@@ -756,8 +864,13 @@ test "Command: redirect stdout to file" {
     try testing.expectEqual(@as(u32, 0), @as(u32, exit.Exited));
 
     // Read our stdout
-    try stdout.seekTo(0);
-    const contents = try stdout.readToEndAlloc(testing.allocator, 1024 * 128);
+    const contents = contents: {
+        const size = (try stdout.stat(testing.io)).size;
+        const data = try testing.allocator.alloc(u8, size);
+        errdefer testing.allocator.free(data);
+        try testing.expectEqual(size, try stdout.readPositionalAll(testing.io, data, 0));
+        break :contents data;
+    };
     defer testing.allocator.free(contents);
     try testing.expect(contents.len > 0);
 }
@@ -765,8 +878,8 @@ test "Command: redirect stdout to file" {
 test "Command: custom env vars" {
     var td = try TempDir.init();
     defer td.deinit();
-    var stdout = try createTestStdout(td.dir);
-    defer stdout.close();
+    var stdout = try createTestStdout(testing.io, td.dir);
+    defer stdout.close(testing.io);
 
     var env = EnvMap.init(testing.allocator);
     defer env.deinit();
@@ -801,8 +914,13 @@ test "Command: custom env vars" {
     try testing.expect(exit.Exited == 0);
 
     // Read our stdout
-    try stdout.seekTo(0);
-    const contents = try stdout.readToEndAlloc(testing.allocator, 4096);
+    const contents = contents: {
+        const size = (try stdout.stat(testing.io)).size;
+        const data = try testing.allocator.alloc(u8, size);
+        errdefer testing.allocator.free(data);
+        try testing.expectEqual(size, try stdout.readPositionalAll(testing.io, data, 0));
+        break :contents data;
+    };
     defer testing.allocator.free(contents);
 
     if (builtin.os.tag == .windows) {
@@ -815,8 +933,8 @@ test "Command: custom env vars" {
 test "Command: custom working directory" {
     var td = try TempDir.init();
     defer td.deinit();
-    var stdout = try createTestStdout(td.dir);
-    defer stdout.close();
+    var stdout = try createTestStdout(testing.io, td.dir);
+    defer stdout.close(testing.io);
 
     var cmd: Command = if (builtin.os.tag == .windows) .{
         .path = "C:\\Windows\\System32\\cmd.exe",
@@ -847,8 +965,13 @@ test "Command: custom working directory" {
     try testing.expect(exit.Exited == 0);
 
     // Read our stdout
-    try stdout.seekTo(0);
-    const contents = try stdout.readToEndAlloc(testing.allocator, 4096);
+    const contents = contents: {
+        const size = (try stdout.stat(testing.io)).size;
+        const data = try testing.allocator.alloc(u8, size);
+        errdefer testing.allocator.free(data);
+        try testing.expectEqual(size, try stdout.readPositionalAll(testing.io, data, 0));
+        break :contents data;
+    };
     defer testing.allocator.free(contents);
 
     if (builtin.os.tag == .windows) {
@@ -872,10 +995,10 @@ test "Command: posix fork handles execveZ failure" {
     }
     var td = try TempDir.init();
     defer td.deinit();
-    var stdout = try createTestStdout(td.dir);
-    defer stdout.close();
-    var stderr = try createTestStderr(td.dir);
-    defer stderr.close();
+    var stdout = try createTestStdout(testing.io, td.dir);
+    defer stdout.close(testing.io);
+    var stderr = try createTestStderr(testing.io, td.dir);
+    defer stderr.close(testing.io);
 
     var cmd: Command = .{
         .path = "/not/a/binary",
@@ -904,7 +1027,7 @@ fn testingStart(self: *Command) !void {
     self.start(testing.allocator) catch |err| {
         if (err == error.ExecFailedInChild) {
             // I am a child process, I must not get confused and continue running the rest of the test suite.
-            posix.exit(1);
+            posix.system.exit(1);
         }
         return err;
     };
diff --git a/src/Surface.zig b/src/Surface.zig
index 2c4edc497..32e91bfa7 100644
--- a/src/Surface.zig
+++ b/src/Surface.zig
@@ -20,7 +20,7 @@ const builtin = @import("builtin");
 const assert = @import("quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
-const global_state = &@import("global.zig").state;
+const global = @import("global.zig");
 const oni = @import("oniguruma");
 const crash = @import("crash/main.zig");
 const unicode = @import("unicode/main.zig");
@@ -168,13 +168,13 @@ readonly: bool = false,
 /// precision timestamp. It does not necessarily need to correspond to the
 /// actual time, but we must be able to compare two subsequent timestamps to get
 /// the wall clock time that has elapsed between timestamps.
-command_timer: ?std.time.Instant = null,
+command_timer: ?std.Io.Timestamp = null,
 
 /// Search state
 search: ?Search = null,
 
 /// Used to rate limit BEL handling.
-last_bell_time: ?std.time.Instant = null,
+last_bell_time: ?std.Io.Timestamp = null,
 
 /// The effect of an input event. This can be used by callers to take
 /// the appropriate action after an input event. For example, key
@@ -559,8 +559,8 @@ pub fn init(
     errdefer renderer_impl.deinit();
 
     // The mutex used to protect our renderer state.
-    const mutex = try alloc.create(std.Thread.Mutex);
-    mutex.* = .{};
+    const mutex = try alloc.create(std.Io.Mutex);
+    mutex.* = .init;
     errdefer alloc.destroy(mutex);
 
     // Create the renderer thread
@@ -581,7 +581,11 @@ pub fn init(
     self.* = .{
         .id = id: {
             while (true) {
-                const candidate = std.crypto.random.int(u64);
+                const candidate = candidate: {
+                    const rng_impl: std.Random.IoSource = .{ .io = global.io() };
+                    const rng = rng_impl.interface();
+                    break :candidate rng.int(u64);
+                };
                 if (candidate == 0) continue;
                 break :id candidate;
             }
@@ -631,13 +635,12 @@ pub fn init(
         var env = rt_surface.defaultTermioEnv() catch |err| env: {
             // If an error occurs, we don't want to block surface startup.
             log.warn("error getting env map for surface err={}", .{err});
-            break :env internal_os.getEnvMap(alloc) catch
-                std.process.EnvMap.init(alloc);
+            break :env global.environMap() catch std.process.Environ.Map.init(alloc);
         };
         errdefer env.deinit();
 
         // don't leak GHOSTTY_LOG to any subprocesses
-        env.remove("GHOSTTY_LOG");
+        _ = env.orderedRemove("GHOSTTY_LOG");
 
         var buf: [18]u8 = undefined;
         try env.put(
@@ -654,7 +657,7 @@ pub fn init(
             .shell_integration_features = config.@"shell-integration-features",
             .cursor_blink = config.@"cursor-style-blink",
             .working_directory = if (config.@"working-directory") |wd| wd.value() else null,
-            .resources_dir = global_state.resources_dir.host(),
+            .resources_dir = global.resourcesDir().host(),
             .term = config.term,
             .rt_pre_exec_info = .init(config),
             .rt_post_fork_info = .init(config),
@@ -717,7 +720,7 @@ pub fn init(
         rendererpkg.Thread.threadMain,
         .{&self.renderer_thread},
     );
-    self.renderer_thr.setName("renderer") catch {};
+    self.renderer_thr.setName(global.io(), "renderer") catch {};
 
     // Start our IO thread
     self.io_thr = try std.Thread.spawn(
@@ -725,7 +728,7 @@ pub fn init(
         termio.Thread.threadMain,
         .{ &self.io_thread, &self.io },
     );
-    self.io_thr.setName("io") catch {};
+    self.io_thr.setName(global.io(), "io") catch {};
 
     // Determine our initial window size if configured. We need to do this
     // quite late in the process because our height/width are in grid dimensions,
@@ -900,14 +903,14 @@ pub fn activateInspector(self: *Surface) !void {
 
     // Put the inspector onto the render state
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         assert(self.renderer_state.inspector == null);
         self.renderer_state.inspector = self.inspector;
     }
 
     // Notify our components we have an inspector active
-    _ = self.renderer_thread.mailbox.push(.{ .inspector = true }, .{ .forever = {} });
+    _ = self.renderer_thread.mailbox.push(global.io(), .{ .inspector = true }, .{ .forever = {} });
     self.queueIo(.{ .inspector = true }, .unlocked);
 }
 
@@ -917,14 +920,14 @@ pub fn deactivateInspector(self: *Surface) void {
 
     // Remove the inspector from the render state
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         assert(self.renderer_state.inspector != null);
         self.renderer_state.inspector = null;
     }
 
     // Notify our components we have deactivated inspector
-    _ = self.renderer_thread.mailbox.push(.{ .inspector = false }, .{ .forever = {} });
+    _ = self.renderer_thread.mailbox.push(global.io(), .{ .inspector = false }, .{ .forever = {} });
     self.queueIo(.{ .inspector = false }, .unlocked);
 
     // Deinit the inspector
@@ -948,8 +951,8 @@ pub fn needsConfirmQuit(self: *Surface) bool {
         .always => true,
         .false => false,
         .true => true: {
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
             break :true !self.io.terminal.cursorIsAtPrompt();
         },
     };
@@ -1096,9 +1099,9 @@ pub fn handleMessage(self: *Surface, msg: Message) !void {
         .password_input => |v| try self.passwordInput(v),
 
         .ring_bell => bell: {
-            const now = std.time.Instant.now() catch unreachable;
+            const now: std.Io.Timestamp = .now(global.io(), .awake);
             if (self.last_bell_time) |last| {
-                if (now.since(last) < 100 * std.time.ns_per_ms) break :bell;
+                if (last.durationTo(now).toMilliseconds() < 100) break :bell;
             }
             self.last_bell_time = now;
             _ = self.rt_app.performAction(
@@ -1126,15 +1129,22 @@ pub fn handleMessage(self: *Surface, msg: Message) !void {
         },
 
         .start_command => {
-            self.command_timer = try .now();
+            self.command_timer = .now(global.io(), .awake);
         },
 
         .stop_command => |v| timer: {
-            const end: std.time.Instant = try .now();
+            const end: std.Io.Timestamp = .now(global.io(), .awake);
             const start = self.command_timer orelse break :timer;
             self.command_timer = null;
+            const duration_raw = start.durationTo(end).nanoseconds;
+            assert(duration_raw >= 0 and duration_raw <= std.math.maxInt(u64));
 
-            const duration: Duration = .{ .duration = end.since(start) };
+            const duration: Duration = .{
+                .duration = @as(
+                    u64,
+                    @intCast(std.math.clamp(start.durationTo(end).nanoseconds, 0, std.math.maxInt(u64))),
+                ),
+            };
             log.debug("command took {f}", .{duration});
 
             _ = self.rt_app.performAction(
@@ -1185,8 +1195,8 @@ fn selectionScrollTick(self: *Surface) !void {
     const pos_vp = self.posToViewport(pos.x, pos.y);
 
     // We need our locked state for the remainder
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     const t: *terminal.Terminal = self.renderer_state.terminal;
 
     const selection = self.mouse.selection_gesture.autoscrollTick(t, .{
@@ -1276,8 +1286,8 @@ fn childExited(self: *Surface, info: apprt.surface.Message.ChildExited) void {
 
         // If the native GUI can't be shown, display a text message in the
         // terminal.
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         const t: *terminal.Terminal = self.renderer_state.terminal;
         t.carriageReturn();
         t.linefeed() catch break :terminal;
@@ -1316,8 +1326,8 @@ fn childExitedAbnormally(
     });
     const runtime_str = try std.fmt.allocPrint(alloc, "{d} ms", .{info.runtime_ms});
 
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     const t: *terminal.Terminal = self.renderer_state.terminal;
 
     // No matter what move the cursor back to the column 0.
@@ -1383,8 +1393,8 @@ fn childExitedAbnormally(
 /// Called when the terminal detects there is a password input prompt.
 fn passwordInput(self: *Surface, v: bool) !void {
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // If our password input state is unchanged then we don't
         // waste time doing anything more.
@@ -1436,6 +1446,7 @@ fn searchCallback_(
             for (matches) |*m| m.* = try m.clone(alloc);
 
             _ = self.renderer_thread.mailbox.push(
+                global.io(),
                 .{ .search_viewport_matches = .{
                     .arena = arena,
                     .matches = matches,
@@ -1454,6 +1465,7 @@ fn searchCallback_(
                 const match = try sel.highlight.clone(alloc);
 
                 _ = self.renderer_thread.mailbox.push(
+                    global.io(),
                     .{ .search_selected_match = .{
                         .arena = arena,
                         .match = match,
@@ -1469,6 +1481,7 @@ fn searchCallback_(
             } else {
                 // Reset our selected match
                 _ = self.renderer_thread.mailbox.push(
+                    global.io(),
                     .{ .search_selected_match = null },
                     .forever,
                 );
@@ -1493,10 +1506,12 @@ fn searchCallback_(
         // When we quit, tell our renderer to reset any search state.
         .quit => {
             _ = self.renderer_thread.mailbox.push(
+                global.io(),
                 .{ .search_selected_match = null },
                 .forever,
             );
             _ = self.renderer_thread.mailbox.push(
+                global.io(),
                 .{ .search_viewport_matches = .{
                     .arena = .init(self.alloc),
                     .matches = &.{},
@@ -1539,8 +1554,8 @@ fn modsChanged(self: *Surface, mods: input.Mods) void {
         // highlight links. Additionally, mark the screen as dirty so
         // that the highlight state of all links is properly updated.
         {
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
             self.renderer_state.mouse.mods = self.mouseModsWithCapture(self.mouse.mods);
 
             // We use the clear screen dirty flag to force a rebuild of all
@@ -1786,7 +1801,7 @@ pub fn updateConfig(
     termio_config_ptr.* = try termio.Termio.DerivedConfig.init(self.alloc, config);
     errdefer termio_config_ptr.deinit();
 
-    _ = self.renderer_thread.mailbox.push(renderer_message, .{ .forever = {} });
+    _ = self.renderer_thread.mailbox.push(global.io(), renderer_message, .{ .forever = {} });
     self.queueIo(.{
         .change_config = .{
             .alloc = self.alloc,
@@ -1907,8 +1922,8 @@ pub fn dumpText(
     alloc: Allocator,
     sel: terminal.Selection,
 ) !Text {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     return try self.dumpTextLocked(alloc, sel);
 }
 
@@ -2033,15 +2048,15 @@ pub fn dumpTextLocked(
 
 /// Returns true if the terminal has a selection.
 pub fn hasSelection(self: *const Surface) bool {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     return self.io.terminal.screens.active.selection != null;
 }
 
 /// Returns the selected text. This is allocated.
 pub fn selectionString(self: *Surface, alloc: Allocator) !?[:0]const u8 {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     const sel = self.io.terminal.screens.active.selection orelse return null;
     return try self.io.terminal.screens.active.selectionString(alloc, .{
         .sel = sel,
@@ -2056,8 +2071,8 @@ pub fn pwd(
     self: *const Surface,
     alloc: Allocator,
 ) Allocator.Error!?[]const u8 {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     const terminal_pwd = self.io.terminal.getPwd() orelse return null;
     return try alloc.dupe(u8, terminal_pwd);
 }
@@ -2074,7 +2089,7 @@ fn resolvePathForOpening(
 
         const resolved = try std.fs.path.resolve(self.alloc, &.{ terminal_pwd, path });
 
-        std.fs.accessAbsolute(resolved, .{}) catch {
+        std.Io.Dir.accessAbsolute(global.io(), resolved, .{}) catch {
             self.alloc.free(resolved);
             return null;
         };
@@ -2088,10 +2103,10 @@ fn resolvePathForOpening(
 /// Returns the x/y coordinate of where the IME (Input Method Editor)
 /// keyboard should be rendered.
 pub fn imePoint(self: *const Surface) apprt.IMEPos {
-    self.renderer_state.mutex.lock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
     const cursor = self.renderer_state.terminal.screens.active.cursor;
     const preedit_width: usize = if (self.renderer_state.preedit) |preedit| preedit.width() else 0;
-    self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.unlock(global.io());
 
     // TODO: need to handle when scrolling and the cursor is not
     // in the visible portion of the screen.
@@ -2440,7 +2455,7 @@ pub fn setFontSize(self: *Surface, size: font.face.DesiredSize) !void {
 
     // Notify our render thread of the new font stack. The renderer
     // MUST accept the new font grid and deref the old.
-    _ = self.renderer_thread.mailbox.push(.{
+    _ = self.renderer_thread.mailbox.push(global.io(), .{
         .font_grid = .{
             .grid = font_grid,
             .set = &self.app.font_grid_set,
@@ -2530,8 +2545,8 @@ pub fn preeditCallback(self: *Surface, preedit_: ?[]const u8) !void {
     crash.sentry.thread_state = self.crashThreadState();
     defer crash.sentry.thread_state = null;
 
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
 
     // We clear our selection when ANY OF:
     // 1. We have an existing preedit
@@ -2566,7 +2581,7 @@ pub fn preeditCallback(self: *Surface, preedit_: ?[]const u8) !void {
 
     // Allocate the codepoints slice
     const Codepoint = rendererpkg.State.Preedit.Codepoint;
-    var codepoints: std.ArrayListUnmanaged(Codepoint) = .{};
+    var codepoints: std.ArrayList(Codepoint) = .empty;
     defer codepoints.deinit(self.alloc);
     while (it.nextCodepoint()) |cp| {
         const width: usize = @intCast(unicode.table.get(cp).width);
@@ -2697,8 +2712,8 @@ pub fn keyCallback(
     )) |v| return v;
     // If we allow KAM and KAM is enabled then we do nothing.
     if (self.config.vt_kam_allowed) {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         if (self.io.terminal.modes.get(.disable_keyboard)) return .consumed;
     }
 
@@ -2728,8 +2743,8 @@ pub fn keyCallback(
         {
             // Refresh our link state
             const pos = self.rt_surface.getCursorPos() catch break :mouse_mods;
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
             self.mouseRefreshLinks(
                 pos,
                 self.posToViewport(pos.x, pos.y),
@@ -2821,8 +2836,8 @@ pub fn keyCallback(
     // some data to send to the pty, then we move the viewport down to the
     // bottom. We also clear the selection for any key other then modifiers.
     if (!event.key.modifier()) {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         if (self.config.selection_clear_on_typing or
             event.key == .escape)
@@ -3253,8 +3268,8 @@ fn encodeKey(
 }
 
 fn encodeKeyOpts(self: *const Surface) input.key_encode.Options {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     const t = &self.io.terminal;
 
     var opts: input.key_encode.Options = .fromTerminal(t);
@@ -3295,7 +3310,7 @@ pub fn occlusionCallback(self: *Surface, visible: bool) !void {
     crash.sentry.thread_state = self.crashThreadState();
     defer crash.sentry.thread_state = null;
 
-    _ = self.renderer_thread.mailbox.push(.{
+    _ = self.renderer_thread.mailbox.push(global.io(), .{
         .visible = visible,
     }, .{ .forever = {} });
     try self.queueRender();
@@ -3315,7 +3330,7 @@ pub fn focusCallback(self: *Surface, focused: bool) !void {
     self.focused = focused;
 
     // Notify our render thread of the new state
-    _ = self.renderer_thread.mailbox.push(.{
+    _ = self.renderer_thread.mailbox.push(global.io(), .{
         .focus = focused,
     }, .{ .forever = {} });
 
@@ -3382,9 +3397,9 @@ pub fn focusCallback(self: *Surface, focused: bool) !void {
 
     // Update the focus state and notify the terminal
     {
-        self.renderer_state.mutex.lock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
         self.io.terminal.flags.focused = focused;
-        self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.unlock(global.io());
         self.queueIo(.{ .focused = focused }, .unlocked);
     }
 }
@@ -3516,8 +3531,8 @@ pub fn scrollCallback(
     // log.info("SCROLL: delta_y={} delta_x={}", .{ y.delta, x.delta });
 
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // If we have an active mouse reporting mode, clear the selection.
         // The selection can occur if the user uses the shift mod key to
@@ -3717,8 +3732,8 @@ fn mouseShiftCapture(self: *const Surface, lock: bool) bool {
         .false, .true => {},
     }
 
-    if (lock) self.renderer_state.mutex.lock();
-    defer if (lock) self.renderer_state.mutex.unlock();
+    if (lock) self.renderer_state.mutex.lockUncancelable(global.io());
+    defer if (lock) self.renderer_state.mutex.unlock(global.io());
 
     // If the terminal explicitly requests it then we always allow it
     // since we processed never/always at this point.
@@ -3739,8 +3754,8 @@ fn mouseShiftCapture(self: *const Surface, lock: bool) bool {
 /// Returns true if the mouse is currently captured by the terminal
 /// (i.e. reporting events).
 pub fn mouseCaptured(self: *Surface) bool {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     return self.io.terminal.flags.mouse_event != .none;
 }
 
@@ -3796,21 +3811,12 @@ pub fn mouseButtonCallback(
 
             // If we are within the interval that the click would register
             // an increment then we do not extend the selection.
-            if (std.time.Instant.now()) |now| {
-                const click_time = self.mouse.selection_gesture.left_click_time orelse
-                    break :extend_selection;
-                const since = now.since(click_time);
-                if (since <= self.config.mouse_interval) {
-                    // Click interval very short, we may be increasing
-                    // click counts so we don't extend the selection.
-                    break :extend_selection;
-                }
-            } else |err| {
-                // This is a weird behavior, I think either behavior is actually
-                // fine. This failure should be exceptionally rare anyways.
-                // My thinking here is that we can't be sure if we should extend
-                // the selection or not so we just don't.
-                log.warn("failed to get time, not extending selection err={}", .{err});
+            const click_time = self.mouse.selection_gesture.left_click_time orelse
+                break :extend_selection;
+            const since = click_time.untilNow(global.io(), .awake);
+            if (since.toNanoseconds() <= self.config.mouse_interval) {
+                // Click interval very short, we may be increasing
+                // click counts so we don't extend the selection.
                 break :extend_selection;
             }
 
@@ -3821,8 +3827,8 @@ pub fn mouseButtonCallback(
     }
 
     if (button == .left and action == .release) {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // The selection gesture tracks whether a press became a drag by
         // comparing the release cell to the original press cell. Resolve the
@@ -3897,8 +3903,8 @@ pub fn mouseButtonCallback(
 
     // Report mouse events if enabled
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         if (self.isMouseReporting()) report: {
             // If we have shift-pressed and we aren't allowed to capture it,
             // then we do not do a mouse report.
@@ -3937,8 +3943,8 @@ pub fn mouseButtonCallback(
     // For left button clicks we always record some information for
     // selection/highlighting purposes.
     if (button == .left and action == .press) click: {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         const t: *terminal.Terminal = self.renderer_state.terminal;
         const screen: *terminal.Screen = self.renderer_state.terminal.screens.active;
 
@@ -3962,12 +3968,8 @@ pub fn mouseButtonCallback(
             break :pin pin;
         };
 
-        const time = std.time.Instant.now() catch |err| time: {
-            log.err("error reading time, mouse multi-click won't work err={}", .{err});
-            break :time null;
-        };
         var press_selection = try self.mouse.selection_gesture.press(t, .{
-            .time = time,
+            .time = std.Io.Timestamp.now(global.io(), .awake),
             .pin = pin,
             .xpos = pos.x,
             .ypos = pos.y,
@@ -4047,8 +4049,8 @@ pub fn mouseButtonCallback(
     // want to be careful in the future we can add a function to apprts
     // that let's us know.
     if (button == .right and action == .press) sel: {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // Get our viewport pin
         const screen: *terminal.Screen = self.renderer_state.terminal.screens.active;
@@ -4119,8 +4121,8 @@ pub fn mouseButtonCallback(
             } else {
                 // Pasting can trigger a lock grab in complete clipboard
                 // request so we need to unlock.
-                self.renderer_state.mutex.unlock();
-                defer self.renderer_state.mutex.lock();
+                self.renderer_state.mutex.unlock(global.io());
+                defer self.renderer_state.mutex.lockUncancelable(global.io());
                 _ = try self.startClipboardRequest(.standard, .paste);
 
                 // We don't need to clear selection because we didn't have
@@ -4134,8 +4136,8 @@ pub fn mouseButtonCallback(
 
                 // Pasting can trigger a lock grab in complete clipboard
                 // request so we need to unlock.
-                self.renderer_state.mutex.unlock();
-                defer self.renderer_state.mutex.lock();
+                self.renderer_state.mutex.unlock(global.io());
+                defer self.renderer_state.mutex.lockUncancelable(global.io());
                 _ = try self.startClipboardRequest(.standard, .paste);
             },
         }
@@ -4428,7 +4430,6 @@ fn openUrl(
     // apprts to handle this themselves.
     log.warn("apprt did not handle open URL action, falling back to default opener", .{});
     try internal_os.open(
-        self.alloc,
         action.kind,
         action.url,
     );
@@ -4474,8 +4475,8 @@ pub fn mousePressureCallback(
     if (self.mouse.click_state[left_idx] == .press and
         stage == .deep)
     select: {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         const sel = self.mouse.selection_gesture.deepPress(
             self.renderer_state.terminal,
@@ -4540,8 +4541,8 @@ pub fn cursorPosCallback(
             try self.queueRender();
         }
 
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // No mouse point so we don't highlight links
         self.renderer_state.mouse.point = null;
@@ -4567,8 +4568,8 @@ pub fn cursorPosCallback(
     self.mouse.over_link = false;
 
     // We are reading/writing state for the remainder
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
 
     // Update our mouse state. We set this to null initially because we only
     // want to set it when we're not selecting or doing any other mouse
@@ -4824,8 +4825,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
 
             // CSI/ESC triggers a scroll.
             {
-                self.renderer_state.mutex.lock();
-                defer self.renderer_state.mutex.unlock();
+                self.renderer_state.mutex.lockUncancelable(global.io());
+                defer self.renderer_state.mutex.unlock(global.io());
                 self.scrollToBottom() catch |err| {
                     log.warn("error scrolling to bottom err={}", .{err});
                 };
@@ -4851,8 +4852,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
 
             // Text triggers a scroll.
             {
-                self.renderer_state.mutex.lock();
-                defer self.renderer_state.mutex.unlock();
+                self.renderer_state.mutex.lockUncancelable(global.io());
+                defer self.renderer_state.mutex.unlock(global.io());
                 self.scrollToBottom() catch |err| {
                     log.warn("error scrolling to bottom err={}", .{err});
                 };
@@ -4864,8 +4865,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             // in cursor keys mode. We're in "normal" mode if cursor
             // keys mode is NOT set.
             const normal = normal: {
-                self.renderer_state.mutex.lock();
-                defer self.renderer_state.mutex.unlock();
+                self.renderer_state.mutex.lockUncancelable(global.io());
+                defer self.renderer_state.mutex.unlock(global.io());
 
                 // With the lock held, we must scroll to the bottom.
                 // We always scroll to the bottom for these inputs.
@@ -4884,8 +4885,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
         },
 
         .reset => {
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
             self.renderer_state.terminal.fullReset();
         },
 
@@ -4955,7 +4956,7 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
                     terminal.search.Thread.threadMain,
                     .{&s.state},
                 );
-                s.thread.setName("search") catch {};
+                s.thread.setName(global.io(), "search") catch {};
 
                 break :init s;
             };
@@ -4968,6 +4969,7 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             }
 
             _ = s.state.mailbox.push(
+                global.io(),
                 .{ .change_needle = try .init(
                     self.alloc,
                     text,
@@ -4980,6 +4982,7 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
         .navigate_search => |nav| {
             const s: *Search = if (self.search) |*s| s else return false;
             _ = s.state.mailbox.push(
+                global.io(),
                 .{ .select = switch (nav) {
                     .next => .next,
                     .previous => .prev,
@@ -4990,8 +4993,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
         },
 
         .copy_to_clipboard => |format| {
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
 
             if (self.io.terminal.screens.active.selection) |sel| {
                 try self.copySelectionToClipboards(
@@ -5022,8 +5025,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             if (!self.mouse.over_link) return false;
             const pos = try self.rt_surface.getCursorPos();
 
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
             if (try self.linkAtPos(pos)) |link_info| {
                 const url_text = switch (link_info.action) {
                     .open => url_text: {
@@ -5168,8 +5171,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             // alternate screen then clear screen does nothing so we want to
             // return false so the keybind can be unconsumed.
             {
-                self.renderer_state.mutex.lock();
-                defer self.renderer_state.mutex.unlock();
+                self.renderer_state.mutex.lockUncancelable(global.io());
+                defer self.renderer_state.mutex.unlock(global.io());
                 if (self.io.terminal.screens.active_key == .alternate) return false;
             }
 
@@ -5192,8 +5195,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
 
         .scroll_to_row => |n| {
             {
-                self.renderer_state.mutex.lock();
-                defer self.renderer_state.mutex.unlock();
+                self.renderer_state.mutex.lockUncancelable(global.io());
+                defer self.renderer_state.mutex.unlock(global.io());
                 const t: *terminal.Terminal = self.renderer_state.terminal;
                 t.screens.active.scroll(.{ .row = n });
             }
@@ -5203,8 +5206,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
 
         .scroll_to_selection => {
             {
-                self.renderer_state.mutex.lock();
-                defer self.renderer_state.mutex.unlock();
+                self.renderer_state.mutex.lockUncancelable(global.io());
+                defer self.renderer_state.mutex.unlock(global.io());
                 const sel = self.io.terminal.screens.active.selection orelse return false;
                 const tl = sel.topLeft(self.io.terminal.screens.active);
                 self.io.terminal.screens.active.scroll(.{ .pin = tl });
@@ -5442,8 +5445,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
         ),
 
         .select_all => {
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
 
             const sel = self.io.terminal.screens.active.selectAll();
             if (sel) |s| {
@@ -5564,7 +5567,7 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             .main => @panic("crash binding action, crashing intentionally"),
 
             .render => {
-                _ = self.renderer_thread.mailbox.push(.{ .crash = {} }, .{ .forever = {} });
+                _ = self.renderer_thread.mailbox.push(global.io(), .{ .crash = {} }, .{ .forever = {} });
                 self.queueRender() catch |err| {
                     // Not a big deal if this fails.
                     log.warn("failed to notify renderer of crash message err={}", .{err});
@@ -5575,8 +5578,8 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
         },
 
         .adjust_selection => |direction| {
-            self.renderer_state.mutex.lock();
-            defer self.renderer_state.mutex.unlock();
+            self.renderer_state.mutex.lockUncancelable(global.io());
+            defer self.renderer_state.mutex.unlock(global.io());
 
             const screen: *terminal.Screen = self.io.terminal.screens.active;
             const sel = if (screen.selection) |*sel| sel else {
@@ -5672,23 +5675,24 @@ fn writeScreenFile(
 
     // Open our scrollback file
     var file = try tmp_dir.dir.createFile(
+        global.io(),
         filename,
         switch (builtin.os.tag) {
             .windows => .{},
-            else => .{ .mode = 0o600 },
+            else => .{ .permissions = .fromMode(0o600) },
         },
     );
-    defer file.close();
+    defer file.close(global.io());
 
     // Screen.dumpString writes byte-by-byte, so buffer it
     var buf: [4096]u8 = undefined;
-    var file_writer = file.writer(&buf);
+    var file_writer = file.writer(global.io(), &buf);
     var buf_writer = &file_writer.interface;
 
     // Write the scrollback contents. This requires a lock.
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // We only dump history if we have history. We still keep
         // the file and write the empty file to the pty so that this
@@ -5751,7 +5755,11 @@ fn writeScreenFile(
 
     // Get the final path
     var path_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath(filename, &path_buf);
+    const path = path_buf[0..try tmp_dir.dir.realPathFile(
+        global.io(),
+        filename,
+        &path_buf,
+    )];
 
     switch (write_screen.action) {
         .copy => {
@@ -5849,8 +5857,8 @@ fn completeClipboardPaste(
     if (data.len == 0) return;
 
     const encode_opts: input.paste.Options = encode_opts: {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         const opts: input.paste.Options = .fromTerminal(&self.io.terminal);
 
         // If we have paste protection enabled, we detect unsafe pastes and return
@@ -5970,12 +5978,12 @@ fn showDesktopNotification(self: *Surface, title: [:0]const u8, body: [:0]const
     // how fast identical notifications can be sent sequentially.
     const hash_algorithm = std.hash.Wyhash;
 
-    const now = try std.time.Instant.now();
+    const now: std.Io.Timestamp = .now(global.io(), .awake);
 
     // Set a limit of one desktop notification per second so that the OS
     // doesn't kill us when we run out of resources.
     if (self.app.last_notification_time) |last| {
-        if (now.since(last) < 1 * std.time.ns_per_s) {
+        if (last.durationTo(now).toSeconds() < 1) {
             log.warn("rate limiting desktop notifications", .{});
             return;
         }
@@ -5992,7 +6000,7 @@ fn showDesktopNotification(self: *Surface, title: [:0]const u8, body: [:0]const
     // notifications with identical content.
     if (self.app.last_notification_time) |last| {
         if (self.app.last_notification_digest == new_digest) {
-            if (now.since(last) < 5 * std.time.ns_per_s) {
+            if (last.durationTo(now).toSeconds() < 5) {
                 log.warn("suppressing identical desktop notification", .{});
                 return;
             }
diff --git a/src/apprt/action.zig b/src/apprt/action.zig
index 4728d73ce..23bff13d7 100644
--- a/src/apprt/action.zig
+++ b/src/apprt/action.zig
@@ -8,6 +8,7 @@ const renderer = @import("../renderer.zig");
 const terminal = @import("../terminal/main.zig");
 const CoreSurface = @import("../Surface.zig");
 const lib = @import("../lib/main.zig");
+const compat_testing = @import("../lib/compat/testing.zig");
 
 /// The target for an action. This is generally the thing that had focus
 /// while the action was made but the concept of "focus" is not guaranteed
@@ -424,8 +425,11 @@ pub const Action = union(Key) {
     /// Sync with: ghostty_action_u
     pub const CValue = cvalue: {
         const key_fields = @typeInfo(Key).@"enum".fields;
-        var union_fields: [key_fields.len]std.builtin.Type.UnionField = undefined;
-        for (key_fields, 0..) |field, i| {
+        var names: [key_fields.len][]const u8 = undefined;
+        var types: [key_fields.len]type = undefined;
+        var attrs: [key_fields.len]std.builtin.Type.UnionField.Attributes = undefined;
+
+        for (key_fields, &names, &types, &attrs) |field, *name, *ty, *attr| {
             const action = @unionInit(Action, field.name, undefined);
             const Type = t: {
                 const Type = @TypeOf(@field(action, field.name));
@@ -434,19 +438,12 @@ pub const Action = union(Key) {
                 break :t Type;
             };
 
-            union_fields[i] = .{
-                .name = field.name,
-                .type = Type,
-                .alignment = @alignOf(Type),
-            };
+            name.* = field.name;
+            ty.* = Type;
+            attr.* = .{ .@"align" = @alignOf(Type) };
         }
 
-        break :cvalue @Type(.{ .@"union" = .{
-            .layout = .@"extern",
-            .tag_type = null,
-            .fields = &union_fields,
-            .decls = &.{},
-        } });
+        break :cvalue @Union(.@"extern", null, &names, &types, &attrs);
     };
 
     /// Sync with: ghostty_action_s
@@ -713,7 +710,7 @@ pub const SetTitle = struct {
     pub fn format(
         value: @This(),
         comptime _: []const u8,
-        _: std.fmt.FormatOptions,
+        _: std.fmt.Options,
         writer: *std.Io.Writer,
     ) !void {
         try writer.print("{s}{{ {s} }}", .{ @typeName(@This()), value.title });
@@ -737,7 +734,7 @@ pub const Pwd = struct {
     pub fn format(
         value: @This(),
         comptime _: []const u8,
-        _: std.fmt.FormatOptions,
+        _: std.fmt.Options,
         writer: *std.Io.Writer,
     ) !void {
         try writer.print("{s}{{ {s} }}", .{ @typeName(@This()), value.pwd });
@@ -765,7 +762,7 @@ pub const DesktopNotification = struct {
     pub fn format(
         value: @This(),
         comptime _: []const u8,
-        _: std.fmt.FormatOptions,
+        _: std.fmt.Options,
         writer: *std.Io.Writer,
     ) !void {
         try writer.print("{s}{{ title: {s}, body: {s} }}", .{
@@ -1008,5 +1005,5 @@ pub const SearchSelected = struct {
 };
 
 test {
-    _ = std.testing.refAllDeclsRecursive(@This());
+    _ = compat_testing.refAllDeclsRecursive(@This());
 }
diff --git a/src/apprt/embedded.zig b/src/apprt/embedded.zig
index 7310159cc..1f3b98e24 100644
--- a/src/apprt/embedded.zig
+++ b/src/apprt/embedded.zig
@@ -11,6 +11,7 @@ const Allocator = std.mem.Allocator;
 const objc = @import("objc");
 const apprt = @import("../apprt.zig");
 const font = @import("../font/main.zig");
+const global = @import("../global.zig");
 const input = @import("../input.zig");
 const internal_os = @import("../os/main.zig");
 const renderer = @import("../renderer.zig");
@@ -333,7 +334,7 @@ pub const App = struct {
         _: apprt.ipc.Target,
         comptime action: apprt.ipc.Action.Key,
         _: apprt.ipc.Action.Value(action),
-    ) (Allocator.Error || std.posix.WriteError || apprt.ipc.Errors)!bool {
+    ) (Allocator.Error || apprt.ipc.Errors)!bool {
         switch (action) {
             .new_window => return false,
             .toggle_quick_terminal => return false,
@@ -372,7 +373,7 @@ pub const Platform = union(PlatformTag) {
 
     /// Initialize a Platform a tag and configuration from the C ABI.
     pub fn init(tag_int: c_int, c_platform: C) !Platform {
-        const tag = try std.meta.intToEnum(PlatformTag, tag_int);
+        const tag = std.enums.fromInt(PlatformTag, tag_int) orelse return error.InvalidEnumTag;
         return switch (tag) {
             .macos => if (MacOS != void) macos: {
                 const config = c_platform.macos;
@@ -490,16 +491,16 @@ pub const Surface = struct {
         if (opts.working_directory) |c_wd| {
             const wd = std.mem.sliceTo(c_wd, 0);
             if (wd.len > 0) wd: {
-                var dir = std.fs.openDirAbsolute(wd, .{}) catch |err| {
+                var dir = std.Io.Dir.openDirAbsolute(global.io(), wd, .{}) catch |err| {
                     log.warn(
                         "error opening requested working directory dir={s} err={}",
                         .{ wd, err },
                     );
                     break :wd;
                 };
-                defer dir.close();
+                defer dir.close(global.io());
 
-                const stat = dir.stat() catch |err| {
+                const stat = dir.stat(global.io()) catch |err| {
                     log.warn(
                         "failed to stat requested working directory dir={s} err={}",
                         .{ wd, err },
@@ -950,32 +951,32 @@ pub const Surface = struct {
         };
     }
 
-    pub fn defaultTermioEnv(self: *const Surface) !std.process.EnvMap {
-        const alloc = self.app.core_app.alloc;
-        var env = try internal_os.getEnvMap(alloc);
+    pub fn defaultTermioEnv(self: *const Surface) !std.process.Environ.Map {
+        _ = self;
+        var env = try global.environMap();
         errdefer env.deinit();
 
         if (comptime builtin.target.os.tag.isDarwin()) {
             if (env.get("__XCODE_BUILT_PRODUCTS_DIR_PATHS") != null) {
-                env.remove("__XCODE_BUILT_PRODUCTS_DIR_PATHS");
-                env.remove("__XPC_DYLD_LIBRARY_PATH");
-                env.remove("DYLD_FRAMEWORK_PATH");
-                env.remove("DYLD_INSERT_LIBRARIES");
-                env.remove("DYLD_LIBRARY_PATH");
-                env.remove("LD_LIBRARY_PATH");
-                env.remove("SECURITYSESSIONID");
-                env.remove("XPC_SERVICE_NAME");
+                _ = env.orderedRemove("__XCODE_BUILT_PRODUCTS_DIR_PATHS");
+                _ = env.orderedRemove("__XPC_DYLD_LIBRARY_PATH");
+                _ = env.orderedRemove("DYLD_FRAMEWORK_PATH");
+                _ = env.orderedRemove("DYLD_INSERT_LIBRARIES");
+                _ = env.orderedRemove("DYLD_LIBRARY_PATH");
+                _ = env.orderedRemove("LD_LIBRARY_PATH");
+                _ = env.orderedRemove("SECURITYSESSIONID");
+                _ = env.orderedRemove("XPC_SERVICE_NAME");
             }
 
             // Remove this so that running `ghostty` within Ghostty works.
-            env.remove("GHOSTTY_MAC_LAUNCH_SOURCE");
+            _ = env.orderedRemove("GHOSTTY_MAC_LAUNCH_SOURCE");
 
             // If we were launched from the desktop then we want to
             // remove the LANGUAGE env var so that we don't inherit
             // our translation settings for Ghostty. If we aren't from
             // the desktop then we didn't set our LANGUAGE var so we
             // don't need to remove it.
-            if (internal_os.launchedFromDesktop()) env.remove("LANGUAGE");
+            if (internal_os.launchedFromDesktop()) _ = env.orderedRemove("LANGUAGE");
         }
 
         return env;
@@ -1000,7 +1001,7 @@ pub const Inspector = struct {
     content_scale: f64 = 1,
 
     /// Our previous instant used to calculate delta time for animations.
-    instant: ?std.time.Instant = null,
+    instant: ?std.Io.Timestamp = null,
 
     const Backend = enum {
         metal,
@@ -1229,9 +1230,9 @@ pub const Inspector = struct {
         const io: *cimgui.c.ImGuiIO = cimgui.c.ImGui_GetIO();
 
         // Determine our delta time
-        const now = try std.time.Instant.now();
+        const now: std.Io.Timestamp = .now(global.io(), .awake);
         io.DeltaTime = if (self.instant) |prev| delta: {
-            const since_ns: f64 = @floatFromInt(now.since(prev));
+            const since_ns: f64 = @floatFromInt(prev.durationTo(now).toNanoseconds());
             const ns_per_s: f64 = @floatFromInt(std.time.ns_per_s);
             const since_s: f32 = @floatCast(since_ns / ns_per_s);
             break :delta @max(0.00001, since_s);
@@ -1242,8 +1243,6 @@ pub const Inspector = struct {
 
 // C API
 pub const CAPI = struct {
-    const global = &@import("../global.zig").state;
-
     /// This is the same as Surface.KeyEvent but this is the raw C API version.
     const KeyEvent = extern struct {
         action: input.Action,
@@ -1300,7 +1299,7 @@ pub const CAPI = struct {
 
         pub fn deinit(self: *Text) void {
             if (self.text) |ptr| {
-                global.alloc.free(ptr[0..self.text_len :0]);
+                global.alloc().free(ptr[0..self.text_len :0]);
             }
         }
     };
@@ -1410,12 +1409,12 @@ pub const CAPI = struct {
         opts: *const apprt.runtime.App.Options,
         config: *const Config,
     ) !*App {
-        const core_app = try CoreApp.create(global.alloc);
+        const core_app = try CoreApp.create(global.alloc());
         errdefer core_app.destroy();
 
         // Create our runtime app
-        var app = try global.alloc.create(App);
-        errdefer global.alloc.destroy(app);
+        var app = try global.alloc().create(App);
+        errdefer global.alloc().destroy(app);
         try app.init(core_app, config, opts.*);
         errdefer app.terminate();
 
@@ -1438,7 +1437,7 @@ pub const CAPI = struct {
     export fn ghostty_app_free(v: *App) void {
         const core_app = v.core_app;
         v.terminate();
-        global.alloc.destroy(v);
+        global.alloc().destroy(v);
         core_app.destroy();
     }
 
@@ -1520,13 +1519,7 @@ pub const CAPI = struct {
 
     /// Update the color scheme of the app.
     export fn ghostty_app_set_color_scheme(v: *App, scheme_raw: c_int) void {
-        const scheme = std.meta.intToEnum(apprt.ColorScheme, scheme_raw) catch {
-            log.warn(
-                "invalid color scheme to ghostty_surface_set_color_scheme value={}",
-                .{scheme_raw},
-            );
-            return;
-        };
+        const scheme = std.enums.fromInt(apprt.ColorScheme, scheme_raw) orelse return;
 
         v.core_app.colorSchemeEvent(v, scheme) catch |err| {
             log.err("error setting color scheme err={}", .{err});
@@ -1612,8 +1605,8 @@ pub const CAPI = struct {
         result: *Text,
     ) bool {
         const core_surface = &surface.core_surface;
-        core_surface.renderer_state.mutex.lock();
-        defer core_surface.renderer_state.mutex.unlock();
+        core_surface.renderer_state.mutex.lockUncancelable(global.io());
+        defer core_surface.renderer_state.mutex.unlock(global.io());
 
         // If we don't have a selection, do nothing.
         const core_sel = core_surface.io.terminal.screens.active.selection orelse return false;
@@ -1632,8 +1625,8 @@ pub const CAPI = struct {
         sel: Selection,
         result: *Text,
     ) bool {
-        surface.core_surface.renderer_state.mutex.lock();
-        defer surface.core_surface.renderer_state.mutex.unlock();
+        surface.core_surface.renderer_state.mutex.lockUncancelable(global.io());
+        defer surface.core_surface.renderer_state.mutex.unlock(global.io());
 
         const core_sel = sel.core(
             surface.core_surface.renderer_state.terminal.screens.active,
@@ -1651,7 +1644,7 @@ pub const CAPI = struct {
 
         // Get our text directly from the core surface.
         const text = core_surface.dumpTextLocked(
-            global.alloc,
+            global.alloc(),
             core_sel,
         ) catch |err| {
             log.warn("error reading text err={}", .{err});
@@ -1730,14 +1723,7 @@ pub const CAPI = struct {
 
     /// Update the color scheme of the surface.
     export fn ghostty_surface_set_color_scheme(surface: *Surface, scheme_raw: c_int) void {
-        const scheme = std.meta.intToEnum(apprt.ColorScheme, scheme_raw) catch {
-            log.warn(
-                "invalid color scheme to ghostty_surface_set_color_scheme value={}",
-                .{scheme_raw},
-            );
-            return;
-        };
-
+        const scheme = std.enums.fromInt(apprt.ColorScheme, scheme_raw) orelse return;
         surface.colorSchemeCallback(scheme);
     }
 
@@ -1891,17 +1877,7 @@ pub const CAPI = struct {
         stage_raw: u32,
         pressure: f64,
     ) void {
-        const stage = std.meta.intToEnum(
-            input.MousePressureStage,
-            stage_raw,
-        ) catch {
-            log.warn(
-                "invalid mouse pressure stage value={}",
-                .{stage_raw},
-            );
-            return;
-        };
-
+        const stage = std.enums.fromInt(input.MousePressureStage, stage_raw) orelse return;
         surface.mousePressureCallback(stage, pressure);
     }
 
@@ -2134,6 +2110,7 @@ pub const CAPI = struct {
         export fn ghostty_surface_set_display_id(ptr: *Surface, display_id: u32) void {
             const surface = &ptr.core_surface;
             _ = surface.renderer_thread.mailbox.push(
+                global.io(),
                 .{ .macos_display_id = display_id },
                 .{ .forever = {} },
             );
@@ -2157,8 +2134,8 @@ pub const CAPI = struct {
             // read the font face. It should not be deferred since
             // we're loading the primary face.
             const grid = ptr.core_surface.renderer.font_grid;
-            grid.lock.lockShared();
-            defer grid.lock.unlockShared();
+            grid.lock.lockSharedUncancelable(global.io());
+            defer grid.lock.unlockShared(global.io());
 
             const collection = &grid.resolver.collection;
             const face = collection.getFace(.{}) catch return null;
@@ -2195,8 +2172,8 @@ pub const CAPI = struct {
             result: *Text,
         ) bool {
             const surface = &ptr.core_surface;
-            surface.renderer_state.mutex.lock();
-            defer surface.renderer_state.mutex.unlock();
+            surface.renderer_state.mutex.lockUncancelable(global.io());
+            defer surface.renderer_state.mutex.unlock(global.io());
 
             // Get our word selection
             const sel = sel: {
diff --git a/src/apprt/gtk/Surface.zig b/src/apprt/gtk/Surface.zig
index 715973671..c5ba39277 100644
--- a/src/apprt/gtk/Surface.zig
+++ b/src/apprt/gtk/Surface.zig
@@ -94,7 +94,7 @@ pub fn setClipboard(
     );
 }
 
-pub fn defaultTermioEnv(self: *Self) !std.process.EnvMap {
+pub fn defaultTermioEnv(self: *Self) !std.process.Environ.Map {
     return try self.surface.defaultTermioEnv();
 }
 
diff --git a/src/apprt/gtk/adw_version.zig b/src/apprt/gtk/adw_version.zig
index 6f7be52da..1ac750fbd 100644
--- a/src/apprt/gtk/adw_version.zig
+++ b/src/apprt/gtk/adw_version.zig
@@ -4,18 +4,16 @@ const std = @import("std");
 // Ghostty, we need to import `adwaita.h` directly to ensure that the version
 // macros match the version of `libadwaita` that we are building/linking
 // against.
-const c = @cImport({
-    @cInclude("adwaita.h");
-});
+const adw_c = @import("adw_c");
 
 const adw = @import("adw");
 
 const log = std.log.scoped(.gtk);
 
 pub const comptime_version: std.SemanticVersion = .{
-    .major = c.ADW_MAJOR_VERSION,
-    .minor = c.ADW_MINOR_VERSION,
-    .patch = c.ADW_MICRO_VERSION,
+    .major = adw_c.ADW_MAJOR_VERSION,
+    .minor = adw_c.ADW_MINOR_VERSION,
+    .patch = adw_c.ADW_MICRO_VERSION,
 };
 
 pub fn getRuntimeVersion() std.SemanticVersion {
@@ -89,14 +87,14 @@ test "versionAtLeast" {
 
     const funs = &.{ atLeast, runtimeAtLeast };
     inline for (funs) |fun| {
-        try testing.expect(fun(c.ADW_MAJOR_VERSION, c.ADW_MINOR_VERSION, c.ADW_MICRO_VERSION));
-        try testing.expect(!fun(c.ADW_MAJOR_VERSION, c.ADW_MINOR_VERSION, c.ADW_MICRO_VERSION + 1));
-        try testing.expect(!fun(c.ADW_MAJOR_VERSION, c.ADW_MINOR_VERSION + 1, c.ADW_MICRO_VERSION));
-        try testing.expect(!fun(c.ADW_MAJOR_VERSION + 1, c.ADW_MINOR_VERSION, c.ADW_MICRO_VERSION));
-        try testing.expect(fun(c.ADW_MAJOR_VERSION - 1, c.ADW_MINOR_VERSION, c.ADW_MICRO_VERSION));
-        try testing.expect(fun(c.ADW_MAJOR_VERSION - 1, c.ADW_MINOR_VERSION + 1, c.ADW_MICRO_VERSION));
-        try testing.expect(fun(c.ADW_MAJOR_VERSION - 1, c.ADW_MINOR_VERSION, c.ADW_MICRO_VERSION + 1));
-        try testing.expect(fun(c.ADW_MAJOR_VERSION, c.ADW_MINOR_VERSION - 1, c.ADW_MICRO_VERSION + 1));
+        try testing.expect(fun(adw_c.ADW_MAJOR_VERSION, adw_c.ADW_MINOR_VERSION, adw_c.ADW_MICRO_VERSION));
+        try testing.expect(!fun(adw_c.ADW_MAJOR_VERSION, adw_c.ADW_MINOR_VERSION, adw_c.ADW_MICRO_VERSION + 1));
+        try testing.expect(!fun(adw_c.ADW_MAJOR_VERSION, adw_c.ADW_MINOR_VERSION + 1, adw_c.ADW_MICRO_VERSION));
+        try testing.expect(!fun(adw_c.ADW_MAJOR_VERSION + 1, adw_c.ADW_MINOR_VERSION, adw_c.ADW_MICRO_VERSION));
+        try testing.expect(fun(adw_c.ADW_MAJOR_VERSION - 1, adw_c.ADW_MINOR_VERSION, adw_c.ADW_MICRO_VERSION));
+        try testing.expect(fun(adw_c.ADW_MAJOR_VERSION - 1, adw_c.ADW_MINOR_VERSION + 1, adw_c.ADW_MICRO_VERSION));
+        try testing.expect(fun(adw_c.ADW_MAJOR_VERSION - 1, adw_c.ADW_MINOR_VERSION, adw_c.ADW_MICRO_VERSION + 1));
+        try testing.expect(fun(adw_c.ADW_MAJOR_VERSION, adw_c.ADW_MINOR_VERSION - 1, adw_c.ADW_MICRO_VERSION + 1));
     }
 }
 
diff --git a/src/apprt/gtk/build/blueprint.zig b/src/apprt/gtk/build/blueprint.zig
index 4920ce6f8..fb3f6ae23 100644
--- a/src/apprt/gtk/build/blueprint.zig
+++ b/src/apprt/gtk/build/blueprint.zig
@@ -6,10 +6,7 @@
 //! Example: blueprint.zig 1 5 output.ui input.blp
 
 const std = @import("std");
-
-pub const c = @cImport({
-    @cInclude("adwaita.h");
-});
+const adw_c = @import("adw_c");
 
 pub const blueprint_compiler_help =
     \\
@@ -26,23 +23,24 @@ pub const blueprint_compiler_help =
 ;
 
 const adwaita_version = std.SemanticVersion{
-    .major = c.ADW_MAJOR_VERSION,
-    .minor = c.ADW_MINOR_VERSION,
-    .patch = c.ADW_MICRO_VERSION,
+    .major = adw_c.ADW_MAJOR_VERSION,
+    .minor = adw_c.ADW_MINOR_VERSION,
+    .patch = adw_c.ADW_MICRO_VERSION,
 };
+
 const required_blueprint_version = std.SemanticVersion{
     .major = 0,
     .minor = 16,
     .patch = 0,
 };
 
-pub fn main() !void {
+pub fn main(init: std.process.Init) !void {
     var debug_allocator: std.heap.DebugAllocator(.{}) = .init;
     defer _ = debug_allocator.deinit();
     const alloc = debug_allocator.allocator();
 
     // Get our args
-    var it = try std.process.argsWithAllocator(alloc);
+    var it = try init.minimal.args.iterateAllocator(alloc);
     defer it.deinit();
     _ = it.next(); // Skip argv0
     const arg_major = it.next() orelse return error.NoMajorVersion;
@@ -63,51 +61,37 @@ pub fn main() !void {
             \\compile this blueprint. Please install it, ensure that it is
             \\available on your PATH, and then retry building Ghostty.
         , .{required_adwaita_version});
-        std.posix.exit(1);
+        std.process.exit(1);
     }
 
     // Version checks
     {
-        var stdout: std.ArrayListUnmanaged(u8) = .empty;
-        defer stdout.deinit(alloc);
-        var stderr: std.ArrayListUnmanaged(u8) = .empty;
-        defer stderr.deinit(alloc);
-
-        var blueprint_compiler = std.process.Child.init(
-            &.{
-                "blueprint-compiler",
-                "--version",
-            },
-            alloc,
-        );
-        blueprint_compiler.stdout_behavior = .Pipe;
-        blueprint_compiler.stderr_behavior = .Pipe;
-        try blueprint_compiler.spawn();
-        try blueprint_compiler.collectOutput(
-            alloc,
-            &stdout,
-            &stderr,
-            std.math.maxInt(u16),
-        );
-        const term = blueprint_compiler.wait() catch |err| switch (err) {
+        const blueprint_compiler = std.process.run(alloc, init.io, .{
+            .argv = &.{ "blueprint-compiler", "--version" },
+        }) catch |err| switch (err) {
             error.FileNotFound => {
                 std.debug.print(
                     \\`blueprint-compiler` not found.
                 ++ blueprint_compiler_help,
                     .{required_blueprint_version},
                 );
-                std.posix.exit(1);
+                std.process.exit(1);
             },
             else => return err,
         };
-        switch (term) {
-            .Exited => |rc| if (rc != 0) std.process.exit(1),
+        defer {
+            alloc.free(blueprint_compiler.stdout);
+            alloc.free(blueprint_compiler.stderr);
+        }
+
+        switch (blueprint_compiler.term) {
+            .exited => |rc| if (rc != 0) std.process.exit(1),
             else => std.process.exit(1),
         }
 
         const version = try std.SemanticVersion.parse(std.mem.trim(
             u8,
-            stdout.items,
+            blueprint_compiler.stdout,
             &std.ascii.whitespace,
         ));
         if (version.order(required_blueprint_version) == .lt) {
@@ -116,57 +100,45 @@ pub fn main() !void {
             ++ blueprint_compiler_help,
                 .{required_blueprint_version},
             );
-            std.posix.exit(1);
+            std.process.exit(1);
         }
     }
 
     // Compilation
     {
-        var stdout: std.ArrayListUnmanaged(u8) = .empty;
-        defer stdout.deinit(alloc);
-        var stderr: std.ArrayListUnmanaged(u8) = .empty;
-        defer stderr.deinit(alloc);
-
-        var blueprint_compiler = std.process.Child.init(
-            &.{
+        const blueprint_compiler = std.process.run(alloc, init.io, .{
+            .argv = &.{
                 "blueprint-compiler",
                 "compile",
                 "--output",
                 output,
                 input,
             },
-            alloc,
-        );
-        blueprint_compiler.stdout_behavior = .Pipe;
-        blueprint_compiler.stderr_behavior = .Pipe;
-        try blueprint_compiler.spawn();
-        try blueprint_compiler.collectOutput(
-            alloc,
-            &stdout,
-            &stderr,
-            std.math.maxInt(u16),
-        );
-        const term = blueprint_compiler.wait() catch |err| switch (err) {
+        }) catch |err| switch (err) {
             error.FileNotFound => {
                 std.debug.print(
                     \\`blueprint-compiler` not found.
                 ++ blueprint_compiler_help,
                     .{required_blueprint_version},
                 );
-                std.posix.exit(1);
+                std.process.exit(1);
             },
             else => return err,
         };
+        defer {
+            alloc.free(blueprint_compiler.stdout);
+            alloc.free(blueprint_compiler.stderr);
+        }
 
-        switch (term) {
-            .Exited => |rc| {
+        switch (blueprint_compiler.term) {
+            .exited => |rc| {
                 if (rc != 0) {
-                    std.debug.print("{s}", .{stderr.items});
+                    std.debug.print("{s}", .{blueprint_compiler.stderr});
                     std.process.exit(1);
                 }
             },
             else => {
-                std.debug.print("{s}", .{stderr.items});
+                std.debug.print("{s}", .{blueprint_compiler.stderr});
                 std.process.exit(1);
             },
         }
diff --git a/src/apprt/gtk/build/gresource.zig b/src/apprt/gtk/build/gresource.zig
index c50ea8cd5..57c32a353 100644
--- a/src/apprt/gtk/build/gresource.zig
+++ b/src/apprt/gtk/build/gresource.zig
@@ -122,18 +122,17 @@ pub fn blueprint(comptime bp: Blueprint) [:0]const u8 {
     }
 }
 
-pub fn main() !void {
-    var debug_allocator: std.heap.DebugAllocator(.{}) = .init;
-    defer _ = debug_allocator.deinit();
-    const alloc = debug_allocator.allocator();
+pub fn main(init: std.process.Init) !void {
+    const alloc = init.arena.allocator();
 
     // Collect the UI files that are passed in as arguments.
-    var ui_files: std.ArrayListUnmanaged([]const u8) = .empty;
+    var ui_files: std.ArrayList([]const u8) = .empty;
     defer {
         for (ui_files.items) |item| alloc.free(item);
         ui_files.deinit(alloc);
     }
-    var it = try std.process.argsWithAllocator(alloc);
+
+    var it = try init.minimal.args.iterateAllocator(alloc);
     defer it.deinit();
     while (it.next()) |arg| {
         if (!std.mem.endsWith(u8, arg, ".ui")) continue;
@@ -144,7 +143,7 @@ pub fn main() !void {
     }
 
     var buf: [4096]u8 = undefined;
-    var stdout = std.fs.File.stdout().writer(&buf);
+    var stdout = std.Io.File.stdout().writer(init.io, &buf);
     const writer = &stdout.interface;
     try writer.writeAll(
         \\<?xml version="1.0" encoding="UTF-8"?>
@@ -152,8 +151,8 @@ pub fn main() !void {
         \\
     );
 
-    try genRoot(writer);
-    try genIcons(writer);
+    try genRoot(init.io, writer);
+    try genIcons(init.io, writer);
     try genUi(alloc, writer, &ui_files);
 
     try writer.writeAll(
@@ -167,19 +166,19 @@ pub fn main() !void {
 /// Generate the icon resources. This works by looking up all the icons
 /// specified by `icon_sizes` in `images/icons/`. They are asserted to exist
 /// by trying to access the file.
-fn genIcons(writer: *std.Io.Writer) !void {
+fn genIcons(io: std.Io, writer: *std.Io.Writer) !void {
     try writer.print(
         \\  <gresource prefix="{s}/icons">
         \\
     , .{build_info.resource_path});
 
-    const cwd = std.fs.cwd();
+    const cwd: std.Io.Dir = .cwd();
     inline for (icon_sizes) |size| {
         // 1x
         {
             const alias = std.fmt.comptimePrint("{d}x{d}", .{ size, size });
             const source = std.fmt.comptimePrint("images/gnome/{d}.png", .{size});
-            try cwd.access(source, .{});
+            try cwd.access(io, source, .{});
             try writer.print(
                 \\    <file alias="{s}/apps/{s}.png">{s}</file>
                 \\
@@ -192,7 +191,7 @@ fn genIcons(writer: *std.Io.Writer) !void {
         {
             const alias = std.fmt.comptimePrint("{d}x{d}@2", .{ size, size });
             const source = std.fmt.comptimePrint("images/gnome/{d}.png", .{size * 2});
-            try cwd.access(source, .{});
+            try cwd.access(io, source, .{});
             try writer.print(
                 \\    <file alias="{s}/apps/{s}.png">{s}</file>
                 \\
@@ -209,19 +208,19 @@ fn genIcons(writer: *std.Io.Writer) !void {
 }
 
 /// Generate the resources at the root prefix.
-fn genRoot(writer: *std.Io.Writer) !void {
+fn genRoot(io: std.Io, writer: *std.Io.Writer) !void {
     try writer.print(
         \\  <gresource prefix="{s}">
         \\
     , .{build_info.resource_path});
 
-    const cwd = std.fs.cwd();
+    const cwd: std.Io.Dir = .cwd();
     inline for (css) |name| {
         const source = std.fmt.comptimePrint(
             "{s}/{s}",
             .{ css_path, name },
         );
-        try cwd.access(source, .{});
+        try cwd.access(io, source, .{});
         try writer.print(
             \\    <file compressed="true" alias="{s}">{s}</file>
             \\
@@ -242,7 +241,7 @@ fn genRoot(writer: *std.Io.Writer) !void {
 fn genUi(
     alloc: Allocator,
     writer: *std.Io.Writer,
-    files: *const std.ArrayListUnmanaged([]const u8),
+    files: *const std.ArrayList([]const u8),
 ) !void {
     try writer.print(
         \\  <gresource prefix="{s}/ui">
diff --git a/src/apprt/gtk/class.zig b/src/apprt/gtk/class.zig
index 942666cf4..a1dba7169 100644
--- a/src/apprt/gtk/class.zig
+++ b/src/apprt/gtk/class.zig
@@ -145,16 +145,24 @@ pub fn Common(
                 /// as the virtual method but the self parameter points to the
                 /// target instead of the original class.
                 fn ImplementFunc(comptime T: type) type {
-                    var params: [fn_info.params.len]std.builtin.Type.Fn.Param = undefined;
-                    @memcpy(&params, fn_info.params);
-                    params[0].type = *ClassInstance(T);
-                    return @Type(.{ .@"fn" = .{
-                        .calling_convention = fn_info.calling_convention,
-                        .is_generic = fn_info.is_generic,
-                        .is_var_args = fn_info.is_var_args,
-                        .return_type = fn_info.return_type,
-                        .params = &params,
-                    } });
+                    var types: [fn_info.params.len]type = undefined;
+                    var attrs: [fn_info.params.len]std.builtin.Type.Fn.Param.Attributes = undefined;
+
+                    for (fn_info.params, &types, &attrs) |info, *ty, *attr| {
+                        ty.* = info.type.?;
+                        attr.* = .{ .@"noalias" = info.is_noalias };
+                    }
+                    types[0] = *ClassInstance(T);
+
+                    return @Fn(
+                        &types,
+                        &attrs,
+                        fn_info.return_type.?,
+                        .{
+                            .@"callconv" = fn_info.calling_convention,
+                            .varargs = fn_info.is_var_args,
+                        },
+                    );
                 }
             };
         }
diff --git a/src/apprt/gtk/class/application.zig b/src/apprt/gtk/class/application.zig
index a627086eb..8243d8e39 100644
--- a/src/apprt/gtk/class/application.zig
+++ b/src/apprt/gtk/class/application.zig
@@ -1,3 +1,4 @@
+const builtin = @import("builtin");
 const std = @import("std");
 const assert = @import("../../../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
@@ -10,16 +11,17 @@ const gtk = @import("gtk");
 
 const build_config = @import("../../../build_config.zig");
 const build_info = @import("../build/info.zig");
-const state = &@import("../../../global.zig").state;
+const global = @import("../../../global.zig");
 const i18n = @import("../../../os/main.zig").i18n;
 const apprt = @import("../../../apprt.zig");
 const CoreApp = @import("../../../App.zig");
+const compat_file = @import("../../../lib/compat/file.zig");
 const configpkg = @import("../../../config.zig");
 const input = @import("../../../input.zig");
 const internal_os = @import("../../../os/main.zig");
 const systemd = @import("../../../os/systemd.zig");
 const terminal = @import("../../../terminal/main.zig");
-const xev = @import("../../../global.zig").xev;
+const xev = global.xev;
 const Binding = @import("../../../input.zig").Binding;
 const CoreConfig = configpkg.Config;
 const CoreSurface = @import("../../../Surface.zig");
@@ -45,6 +47,8 @@ const OpenURI = @import("../portal.zig").OpenURI;
 
 const log = std.log.scoped(.gtk_ghostty_application);
 
+extern "c" fn setenv(name: ?[*]const u8, value: ?[*]const u8, overwrite: c_int) c_int;
+
 /// Function used to funnel GLib/GObject/GTK log messages into Zig's logging
 /// system rather than just getting dumped directly to stderr.
 fn glibLogWriterFunction(
@@ -271,15 +275,17 @@ pub const Application = extern struct {
         };
         defer config.deinit();
 
+        // Set the old language,
         const saved_language: ?[:0]const u8 = saved_language: {
             const old_language = old_language: {
-                const result = (internal_os.getenv(alloc, "LANG") catch break :old_language null) orelse break :old_language null;
-                defer result.deinit(alloc);
-                break :old_language alloc.dupeZ(u8, result.value) catch break :old_language null;
+                const lang = global.environ().getPosix("LANG") orelse break :old_language null;
+                break :old_language alloc.dupeSentinel(u8, @ptrCast(lang), 0) catch null;
             };
-
-            if (config.language) |language| _ = internal_os.setenv("LANG", language);
-
+            if (config.language) |language| {
+                // Override LANG if we need to (sync global environs if so)
+                _ = setenv("LANG", @ptrCast(language), 1);
+                global.syncEnviron();
+            }
             break :saved_language old_language;
         };
 
@@ -294,7 +300,7 @@ pub const Application = extern struct {
 
         // Setup our GTK init env vars
         setGtkEnv(&config) catch |err| switch (err) {
-            error.NoSpaceLeft => {
+            error.WriteFailed => {
                 // If we fail to set GTK environment variables then we still
                 // try to start the application...
                 log.warn(
@@ -338,7 +344,7 @@ pub const Application = extern struct {
             // I'm unsure of any scenario where this happens. Because we don't
             // want to litter null checks everywhere, we just exit here.
             log.warn("gdk display is null, exiting", .{});
-            std.posix.exit(1);
+            std.process.exit(1);
         };
 
         // Setup our windowing protocol logic
@@ -1063,7 +1069,11 @@ pub const Application = extern struct {
         }
     }
 
-    fn loadCustomCss(self: *Self) (std.fs.File.ReadError || Allocator.Error)!void {
+    const LoadCustomCssError = std.Io.File.OpenError ||
+        compat_file.ReadToEndAllocError ||
+        std.mem.Allocator.Error;
+
+    fn loadCustomCss(self: *Self) LoadCustomCssError!void {
         const priv: *Private = self.private();
         const alloc = self.allocator();
         const display = gdk.Display.getDefault() orelse {
@@ -1087,7 +1097,11 @@ pub const Application = extern struct {
                 .optional => |path| .{ path, true },
                 .required => |path| .{ path, false },
             };
-            const file = std.fs.openFileAbsolute(path, .{}) catch |err| {
+            const file = std.Io.Dir.openFileAbsolute(
+                global.io(),
+                path,
+                .{},
+            ) catch |err| {
                 if (err != error.FileNotFound or !optional) {
                     log.warn(
                         "error opening gtk-custom-css file {s}: {}",
@@ -1096,12 +1110,14 @@ pub const Application = extern struct {
                 }
                 continue;
             };
-            defer file.close();
+            defer file.close(global.io());
 
             const css_file_size_limit = 5 * 1024 * 1024; // 5MB
 
             log.info("loading gtk-custom-css path={s}", .{path});
-            const contents = file.readToEndAlloc(
+
+            const contents = compat_file.readToEndAlloc(
+                file,
                 alloc,
                 css_file_size_limit,
             ) catch |err| switch (err) {
@@ -1111,6 +1127,7 @@ pub const Application = extern struct {
                 },
                 else => |e| return e,
             };
+
             defer alloc.free(contents);
 
             const bytes = glib.Bytes.new(contents.ptr, contents.len);
@@ -1401,7 +1418,7 @@ pub const Application = extern struct {
         const priv = self.private();
         assert(priv.signal_source == null);
         priv.signal_source = glib.unixSignalAdd(
-            std.posix.SIG.USR2,
+            @intFromEnum(std.posix.SIG.USR2),
             handleSigusr2,
             self,
         );
@@ -1461,7 +1478,7 @@ pub const Application = extern struct {
 
         // Queue a new window
         const priv = self.private();
-        _ = priv.core_app.mailbox.push(.{
+        _ = priv.core_app.mailbox.push(global.io(), .{
             .new_window = .{},
         }, .{ .forever = {} });
 
@@ -1813,7 +1830,7 @@ pub const Application = extern struct {
         _: ?*glib.Variant,
         self: *Self,
     ) callconv(.c) void {
-        _ = self.core().mailbox.push(.open_config, .forever);
+        _ = self.core().mailbox.push(global.io(), .open_config, .forever);
     }
 
     fn actionPresentSurface(
@@ -1839,6 +1856,7 @@ pub const Application = extern struct {
         const surface = self.core().findSurfaceByID(surface_id) orelse return;
 
         _ = self.core().mailbox.push(
+            global.io(),
             .{
                 .surface_message = .{
                     .surface = surface,
@@ -1866,11 +1884,8 @@ pub const Application = extern struct {
         fn init(class: *Class) callconv(.c) void {
             // Register our compiled resources exactly once.
             {
-                const c = @cImport({
-                    // generated header files
-                    @cInclude("ghostty_resources.h");
-                });
-                if (c.ghostty_get_resource()) |ptr| {
+                const ghostty_gtk_resources = @import("ghostty_gtk_resources");
+                if (ghostty_gtk_resources.ghostty_get_resource()) |ptr| {
                     gio.resourcesRegister(@ptrCast(@alignCast(ptr)));
                 } else {
                     // If we fail to load resources then things will
@@ -1894,11 +1909,11 @@ pub const Application = extern struct {
     };
 
     pub fn openUrlFallback(self: *Application, kind: apprt.action.OpenUrl.Kind, url: []const u8) void {
+        _ = self;
         // Fallback to the minimal cross-platform way of opening a URL.
         // This is always a safe fallback and enables for example Windows
         // to open URLs (GTK on Windows via WSL is a thing).
         internal_os.open(
-            self.allocator(),
             kind,
             url,
         ) catch |err| log.warn("unable to open url: {}", .{err});
@@ -2846,7 +2861,7 @@ const Action = struct {
 /// given the runtime environment or configuration.
 ///
 /// This must be called BEFORE GTK initialization.
-fn setGtkEnv(config: *const CoreConfig) error{NoSpaceLeft}!void {
+fn setGtkEnv(config: *const CoreConfig) std.Io.Writer.Error!void {
     assert(gtk.isInitialized() == 0);
 
     var gdk_debug: struct {
@@ -2863,7 +2878,7 @@ fn setGtkEnv(config: *const CoreConfig) error{NoSpaceLeft}!void {
     } = .{
         // `gtk-opengl-debug` dumps logs directly to stderr so both must be true
         // to enable OpenGL debugging.
-        .opengl = state.logging.stderr and config.@"gtk-opengl-debug",
+        .opengl = global.logging().stderr and config.@"gtk-opengl-debug",
     };
 
     var gdk_disable: struct {
@@ -2915,8 +2930,7 @@ fn setGtkEnv(config: *const CoreConfig) error{NoSpaceLeft}!void {
 
     {
         var buf: [1024]u8 = undefined;
-        var fmt = std.io.fixedBufferStream(&buf);
-        const writer = fmt.writer();
+        var writer: std.Io.Writer = .fixed(&buf);
         var first: bool = true;
         inline for (@typeInfo(@TypeOf(gdk_debug)).@"struct".fields) |field| {
             if (@field(gdk_debug, field.name)) {
@@ -2926,15 +2940,14 @@ fn setGtkEnv(config: *const CoreConfig) error{NoSpaceLeft}!void {
             }
         }
         try writer.writeByte(0);
-        const value = fmt.getWritten();
+        const value = writer.buffered();
         log.warn("setting GDK_DEBUG={s}", .{value[0 .. value.len - 1]});
-        _ = internal_os.setenv("GDK_DEBUG", value[0 .. value.len - 1 :0]);
+        _ = setenv("GDK_DEBUG", @ptrCast(value[0 .. value.len - 1 :0]), 1);
     }
 
     {
         var buf: [1024]u8 = undefined;
-        var fmt = std.io.fixedBufferStream(&buf);
-        const writer = fmt.writer();
+        var writer: std.Io.Writer = .fixed(&buf);
         var first: bool = true;
         inline for (@typeInfo(@TypeOf(gdk_disable)).@"struct".fields) |field| {
             if (@field(gdk_disable, field.name)) {
@@ -2944,10 +2957,13 @@ fn setGtkEnv(config: *const CoreConfig) error{NoSpaceLeft}!void {
             }
         }
         try writer.writeByte(0);
-        const value = fmt.getWritten();
+        const value = writer.buffered();
         log.warn("setting GDK_DISABLE={s}", .{value[0 .. value.len - 1]});
-        _ = internal_os.setenv("GDK_DISABLE", value[0 .. value.len - 1 :0]);
+        _ = setenv("GDK_DISABLE", @ptrCast(value[0 .. value.len - 1 :0]), 1);
     }
+
+    // Sync environ after altering system env
+    global.syncEnviron();
 }
 
 fn findActiveWindow(data: ?*const anyopaque, _: ?*const anyopaque) callconv(.c) c_int {
diff --git a/src/apprt/gtk/class/command_palette.zig b/src/apprt/gtk/class/command_palette.zig
index 6101e82e8..0d66bbe94 100644
--- a/src/apprt/gtk/class/command_palette.zig
+++ b/src/apprt/gtk/class/command_palette.zig
@@ -153,7 +153,7 @@ pub const CommandPalette = extern struct {
         priv.source.removeAll();
 
         const alloc = Application.default().allocator();
-        var commands: std.ArrayList(*Command) = .{};
+        var commands: std.ArrayList(*Command) = .empty;
         defer {
             for (commands.items) |cmd| cmd.unref();
             commands.deinit(alloc);
diff --git a/src/apprt/gtk/class/global_shortcuts.zig b/src/apprt/gtk/class/global_shortcuts.zig
index 28987c259..dd44afbdd 100644
--- a/src/apprt/gtk/class/global_shortcuts.zig
+++ b/src/apprt/gtk/class/global_shortcuts.zig
@@ -4,6 +4,7 @@ const Allocator = std.mem.Allocator;
 const gio = @import("gio");
 const glib = @import("glib");
 const gobject = @import("gobject");
+const global = @import("../../../global.zig");
 
 const Binding = @import("../../../input.zig").Binding;
 const key = @import("../key.zig");
@@ -630,6 +631,9 @@ fn generateToken(buf: *Token) [:0]const u8 {
     return std.fmt.bufPrintZ(
         buf,
         "ghostty_{x:0<7}",
-        .{std.crypto.random.int(u28)},
+        .{rand_int: {
+            const rng_impl: std.Random.IoSource = .{ .io = global.io() };
+            break :rand_int rng_impl.interface().int(u28);
+        }},
     ) catch unreachable;
 }
diff --git a/src/apprt/gtk/class/imgui_widget.zig b/src/apprt/gtk/class/imgui_widget.zig
index 0ef753a87..50247fbf1 100644
--- a/src/apprt/gtk/class/imgui_widget.zig
+++ b/src/apprt/gtk/class/imgui_widget.zig
@@ -7,6 +7,7 @@ const adw = @import("adw");
 const gdk = @import("gdk");
 const gobject = @import("gobject");
 const gtk = @import("gtk");
+const global = @import("../../../global.zig");
 
 const input = @import("../../../input.zig");
 const gresource = @import("../build/gresource.zig");
@@ -61,13 +62,13 @@ pub const ImguiWidget = extern struct {
         ig_context: ?*cimgui.c.ImGuiContext = null,
 
         /// Our previous instant used to calculate delta time for animations.
-        instant: ?std.time.Instant = null,
+        instant: ?std.Io.Timestamp = null,
 
         /// Tick callback ID for timed updates.
         tick_callback_id: c_uint = 0,
 
         /// Last render time for throttling to 30 FPS.
-        last_render_time: ?std.time.Instant = null,
+        last_render_time: ?std.Io.Timestamp = null,
 
         pub var offset: c_int = 0;
     };
@@ -140,10 +141,11 @@ pub const ImguiWidget = extern struct {
         const priv = self.private();
         const io: *cimgui.c.ImGuiIO = cimgui.c.ImGui_GetIO();
 
+        const now: std.Io.Timestamp = .now(global.io(), .awake);
+
         // Determine our delta time
-        const now = std.time.Instant.now() catch unreachable;
         io.DeltaTime = if (priv.instant) |prev| delta: {
-            const since_ns: f64 = @floatFromInt(now.since(prev));
+            const since_ns: f64 = @floatFromInt(prev.durationTo(now).nanoseconds);
             const ns_per_s: f64 = @floatFromInt(std.time.ns_per_s);
             const since_s: f32 = @floatCast(since_ns / ns_per_s);
             break :delta @max(0.00001, since_s);
@@ -298,7 +300,7 @@ pub const ImguiWidget = extern struct {
 
         // Update last render time for tick callback throttling.
         const priv = self.private();
-        priv.last_render_time = std.time.Instant.now() catch null;
+        priv.last_render_time = .now(global.io(), .awake);
 
         // Setup our frame. We render twice because some ImGui behaviors
         // take multiple renders to process. I don't know how to make this
@@ -457,15 +459,10 @@ pub const ImguiWidget = extern struct {
         const self: *Self = gobject.ext.cast(Self, widget) orelse return 0;
         const priv = self.private();
 
-        const now = std.time.Instant.now() catch {
-            self.queueRender();
-            return 1;
-        };
-
         // Throttle to 30 FPS (~33ms between frames)
         const frame_time_ns: u64 = std.time.ns_per_s / 30;
         const should_render = if (priv.last_render_time) |last|
-            now.since(last) >= frame_time_ns
+            last.untilNow(global.io(), .awake).nanoseconds >= frame_time_ns
         else
             true;
 
diff --git a/src/apprt/gtk/class/surface.zig b/src/apprt/gtk/class/surface.zig
index 54825ce05..3a950a6aa 100644
--- a/src/apprt/gtk/class/surface.zig
+++ b/src/apprt/gtk/class/surface.zig
@@ -36,6 +36,7 @@ const Window = @import("window.zig").Window;
 const InspectorWindow = @import("inspector_window.zig").InspectorWindow;
 const i18n = @import("../../../os/i18n.zig");
 const media = @import("../media.zig");
+const global = @import("../../../global.zig");
 
 const log = std.log.scoped(.gtk_ghostty_surface);
 
@@ -1589,32 +1590,35 @@ pub const Surface = extern struct {
         return self.private().cursor_pos;
     }
 
-    pub fn defaultTermioEnv(self: *Self) !std.process.EnvMap {
+    pub fn defaultTermioEnv(self: *Self) !std.process.Environ.Map {
         const app = Application.default();
         const alloc = app.allocator();
-        var env = try internal_os.getEnvMap(alloc);
+        var env = if (internal_os.isFlatpak())
+            std.process.Environ.Map.init(alloc)
+        else
+            try global.environMap();
         errdefer env.deinit();
 
         if (app.savedLanguage()) |language| {
             try env.put("LANG", language);
         } else {
-            env.remove("LANG");
+            _ = env.orderedRemove("LANG");
         }
 
         // Don't leak these GTK environment variables to child processes.
-        env.remove("GDK_DEBUG");
-        env.remove("GDK_DISABLE");
-        env.remove("GSK_RENDERER");
+        _ = env.orderedRemove("GDK_DEBUG");
+        _ = env.orderedRemove("GDK_DISABLE");
+        _ = env.orderedRemove("GSK_RENDERER");
 
         // Remove some environment variables that are set when Ghostty is launched
         // from a `.desktop` file, by D-Bus activation, or systemd.
-        env.remove("GIO_LAUNCHED_DESKTOP_FILE");
-        env.remove("GIO_LAUNCHED_DESKTOP_FILE_PID");
-        env.remove("DBUS_STARTER_ADDRESS");
-        env.remove("DBUS_STARTER_BUS_TYPE");
-        env.remove("INVOCATION_ID");
-        env.remove("JOURNAL_STREAM");
-        env.remove("NOTIFY_SOCKET");
+        _ = env.orderedRemove("GIO_LAUNCHED_DESKTOP_FILE");
+        _ = env.orderedRemove("GIO_LAUNCHED_DESKTOP_FILE_PID");
+        _ = env.orderedRemove("DBUS_STARTER_ADDRESS");
+        _ = env.orderedRemove("DBUS_STARTER_BUS_TYPE");
+        _ = env.orderedRemove("INVOCATION_ID");
+        _ = env.orderedRemove("JOURNAL_STREAM");
+        _ = env.orderedRemove("NOTIFY_SOCKET");
 
         // Unset environment varies set by snaps if we're running in a snap.
         // This allows Ghostty to further launch additional snaps.
@@ -1641,7 +1645,7 @@ pub const Surface = extern struct {
     }
 
     /// Filter out environment variables that start with forbidden prefixes.
-    fn filterSnapPaths(gpa: std.mem.Allocator, env_map: *std.process.EnvMap) !void {
+    fn filterSnapPaths(gpa: std.mem.Allocator, env_map: *std.process.Environ.Map) !void {
         comptime assert(build_config.snap);
 
         const snap_vars = [_][]const u8{
@@ -1708,7 +1712,7 @@ pub const Surface = extern struct {
             item.key,
             item.value,
         );
-        for (env_to_remove.items) |key| _ = env_map.remove(key);
+        for (env_to_remove.items) |key| _ = env_map.orderedRemove(key);
     }
 
     pub fn clipboardRequest(
diff --git a/src/apprt/gtk/ext/actions.zig b/src/apprt/gtk/ext/actions.zig
index 3232bc18b..6ba9c678b 100644
--- a/src/apprt/gtk/ext/actions.zig
+++ b/src/apprt/gtk/ext/actions.zig
@@ -176,7 +176,11 @@ test "adding actions to an object" {
         _ = addAsGroup(gtk.Box, box, "test", &actions);
     }
 
-    const expected = std.crypto.random.intRangeAtMost(i32, 1, std.math.maxInt(u31));
+    const expected = expected: {
+        const rng_impl: std.Random.IoSource = .{ .io = testing.io };
+        const rng = rng_impl.interface();
+        break :expected rng.intRangeAtMost(i32, 1, std.math.maxInt(u31));
+    };
     const parameter = glib.Variant.newInt32(expected);
 
     try testing.expect(box.as(gtk.Widget).activateActionVariant("test.test", parameter) != 0);
diff --git a/src/apprt/gtk/gtk_version.zig b/src/apprt/gtk/gtk_version.zig
index 71edb076d..97e0a5236 100644
--- a/src/apprt/gtk/gtk_version.zig
+++ b/src/apprt/gtk/gtk_version.zig
@@ -3,18 +3,16 @@ const std = @import("std");
 // Until the gobject bindings are built at the same time we are building
 // Ghostty, we need to import `gtk/gtk.h` directly to ensure that the version
 // macros match the version of `gtk4` that we are building/linking against.
-const c = @cImport({
-    @cInclude("gtk/gtk.h");
-});
+const gtk_c = @import("gtk_c");
 
 const gtk = @import("gtk");
 
 const log = std.log.scoped(.gtk);
 
 pub const comptime_version: std.SemanticVersion = .{
-    .major = c.GTK_MAJOR_VERSION,
-    .minor = c.GTK_MINOR_VERSION,
-    .patch = c.GTK_MICRO_VERSION,
+    .major = gtk_c.GTK_MAJOR_VERSION,
+    .minor = gtk_c.GTK_MINOR_VERSION,
+    .patch = gtk_c.GTK_MICRO_VERSION,
 };
 
 pub fn getRuntimeVersion() std.SemanticVersion {
@@ -105,17 +103,17 @@ test "atLeast" {
 
     const funs = &.{ atLeast, runtimeAtLeast };
     inline for (funs) |fun| {
-        try testing.expect(fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION));
 
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION + 1));
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION + 1, c.GTK_MICRO_VERSION));
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION + 1, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION + 1));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION + 1, gtk_c.GTK_MICRO_VERSION));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION + 1, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION));
 
-        try testing.expect(fun(c.GTK_MAJOR_VERSION - 1, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION));
-        try testing.expect(fun(c.GTK_MAJOR_VERSION - 1, c.GTK_MINOR_VERSION + 1, c.GTK_MICRO_VERSION));
-        try testing.expect(fun(c.GTK_MAJOR_VERSION - 1, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION + 1));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION - 1, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION - 1, gtk_c.GTK_MINOR_VERSION + 1, gtk_c.GTK_MICRO_VERSION));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION - 1, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION + 1));
 
-        try testing.expect(fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION - 1, c.GTK_MICRO_VERSION + 1));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION - 1, gtk_c.GTK_MICRO_VERSION + 1));
     }
 }
 
@@ -125,16 +123,16 @@ test "runtimeUntil" {
     // This is an array in case we add a comptime variant.
     const funs = &.{runtimeUntil};
     inline for (funs) |fun| {
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION));
 
-        try testing.expect(fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION + 1));
-        try testing.expect(fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION + 1, c.GTK_MICRO_VERSION));
-        try testing.expect(fun(c.GTK_MAJOR_VERSION + 1, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION + 1));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION + 1, gtk_c.GTK_MICRO_VERSION));
+        try testing.expect(fun(gtk_c.GTK_MAJOR_VERSION + 1, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION));
 
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION - 1, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION));
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION - 1, c.GTK_MINOR_VERSION + 1, c.GTK_MICRO_VERSION));
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION - 1, c.GTK_MINOR_VERSION, c.GTK_MICRO_VERSION + 1));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION - 1, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION - 1, gtk_c.GTK_MINOR_VERSION + 1, gtk_c.GTK_MICRO_VERSION));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION - 1, gtk_c.GTK_MINOR_VERSION, gtk_c.GTK_MICRO_VERSION + 1));
 
-        try testing.expect(!fun(c.GTK_MAJOR_VERSION, c.GTK_MINOR_VERSION - 1, c.GTK_MICRO_VERSION + 1));
+        try testing.expect(!fun(gtk_c.GTK_MAJOR_VERSION, gtk_c.GTK_MINOR_VERSION - 1, gtk_c.GTK_MICRO_VERSION + 1));
     }
 }
diff --git a/src/apprt/gtk/ipc/DBus.zig b/src/apprt/gtk/ipc/DBus.zig
index fa4a6723e..669047833 100644
--- a/src/apprt/gtk/ipc/DBus.zig
+++ b/src/apprt/gtk/ipc/DBus.zig
@@ -6,6 +6,7 @@ const Allocator = std.mem.Allocator;
 
 const gio = @import("gio");
 const glib = @import("glib");
+const global = @import("../../../global.zig");
 
 const apprt = @import("../../../apprt.zig");
 const ApprtApp = @import("../App.zig");
@@ -28,10 +29,12 @@ payload_builder: *glib.VariantBuilder,
 /// Used to build the parameters for the IPC.
 parameters_builder: *glib.VariantBuilder,
 
+pub const InitError = Allocator.Error || std.Io.Writer.Error || apprt.ipc.Errors;
+
 /// Initialize the helper.
-pub fn init(alloc: Allocator, target: apprt.ipc.Target, action: [:0]const u8) (Allocator.Error || std.Io.Writer.Error || apprt.ipc.Errors)!Self {
+pub fn init(alloc: Allocator, target: apprt.ipc.Target, action: [:0]const u8) InitError!Self {
     var buf: [256]u8 = undefined;
-    var stderr_writer = std.fs.File.stderr().writer(&buf);
+    var stderr_writer = std.Io.File.stderr().writer(global.io(), &buf);
     const stderr = &stderr_writer.interface;
 
     // Get the appropriate bus name and object path for contacting the
@@ -133,7 +136,7 @@ pub fn addParameter(self: *Self, variant: *glib.Variant) void {
 /// should be done with this object other than call `deinit`.
 pub fn send(self: *Self) (std.Io.Writer.Error || apprt.ipc.Errors)!void {
     var buf: [256]u8 = undefined;
-    var stderr_writer = std.fs.File.stderr().writer(&buf);
+    var stderr_writer = std.Io.File.stderr().writer(global.io(), &buf);
     const stderr = &stderr_writer.interface;
 
     // finish building the parameters
diff --git a/src/apprt/gtk/media.zig b/src/apprt/gtk/media.zig
index 7883bf372..3e6a19c33 100644
--- a/src/apprt/gtk/media.zig
+++ b/src/apprt/gtk/media.zig
@@ -7,10 +7,15 @@ const gio = @import("gio");
 const glib = @import("glib");
 const gobject = @import("gobject");
 const gtk = @import("gtk");
+const global = @import("../../global.zig");
 
 pub fn fromFilename(path: [:0]const u8) ?*gtk.MediaFile {
     assert(std.fs.path.isAbsolute(path));
-    std.fs.accessAbsolute(path, .{ .mode = .read_only }) catch |err| {
+    std.Io.Dir.accessAbsolute(
+        global.io(),
+        path,
+        .{ .read = true },
+    ) catch |err| {
         log.warn("unable to access {s}: {t}", .{ path, err });
         return null;
     };
diff --git a/src/apprt/gtk/portal.zig b/src/apprt/gtk/portal.zig
index 3e51042d6..11c3356d7 100644
--- a/src/apprt/gtk/portal.zig
+++ b/src/apprt/gtk/portal.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 
 const gio = @import("gio");
+const global = @import("../../global.zig");
 
 const Allocator = std.mem.Allocator;
 
@@ -11,7 +12,8 @@ const token_format = std.fmt.comptimePrint("{{x:0>{}}}", .{token_hex_len});
 
 /// Generate a token suitable for use in requests to the XDG Desktop Portal
 pub fn generateToken() usize {
-    return std.crypto.random.int(usize);
+    const rng_impl: std.Random.IoSource = .{ .io = global.io() };
+    return rng_impl.interface().int(usize);
 }
 
 /// Format a request token consistently for use in portal object paths and payloads.
diff --git a/src/apprt/gtk/portal/OpenURI.zig b/src/apprt/gtk/portal/OpenURI.zig
index 97aa013e5..401914825 100644
--- a/src/apprt/gtk/portal/OpenURI.zig
+++ b/src/apprt/gtk/portal/OpenURI.zig
@@ -9,6 +9,7 @@ const assert = std.debug.assert;
 const gio = @import("gio");
 const glib = @import("glib");
 const gobject = @import("gobject");
+const global = @import("../../../global.zig");
 
 const App = @import("../App.zig");
 const portal = @import("../portal.zig");
@@ -23,7 +24,7 @@ app: *App,
 dbus: ?*gio.DBusConnection = null,
 
 /// Mutex to protect modification of the entries map or the cleanup timer.
-mutex: std.Thread.Mutex = .{},
+mutex: std.Io.Mutex = .init,
 
 /// Map to store data about any in-flight calls to the portal.
 entries: std.AutoArrayHashMapUnmanaged(usize, *Entry) = .empty,
@@ -78,7 +79,7 @@ const RequestData = struct {
 /// Data about any in-flight calls to the portal.
 pub const Entry = struct {
     /// When the request started.
-    start: std.time.Instant,
+    start: std.Io.Timestamp,
     /// A token used by the portal to identify requests and responses. The
     /// actual format of the token does not really matter as long as it can be
     /// used as part of a D-Bus object path. `usize` was chosen since it's easy
@@ -123,8 +124,8 @@ pub fn setDbusConnection(self: *OpenURI, dbus: ?*gio.DBusConnection) void {
 pub fn deinit(self: *OpenURI) void {
     const alloc = self.app.app.allocator();
 
-    self.mutex.lock();
-    defer self.mutex.unlock();
+    self.mutex.lockUncancelable(global.io());
+    defer self.mutex.unlock(global.io());
 
     if (!self.alive) return;
     self.alive = false;
@@ -157,8 +158,8 @@ pub fn start(self: *OpenURI, value: apprt.action.OpenUrl) (Allocator.Error || Er
         alloc.destroy(request);
     }
 
-    self.mutex.lock();
-    defer self.mutex.unlock();
+    self.mutex.lockUncancelable(global.io());
+    defer self.mutex.unlock(global.io());
 
     // Create an entry that is used to track the results of the D-Bus method
     // call.
@@ -166,7 +167,7 @@ pub fn start(self: *OpenURI, value: apprt.action.OpenUrl) (Allocator.Error || Er
         const entry = try alloc.create(Entry);
         errdefer alloc.destroy(entry);
         entry.* = .{
-            .start = std.time.Instant.now() catch return error.TimerUnavailable,
+            .start = std.Io.Timestamp.now(global.io(), .awake),
             .token = token,
             .kind = value.kind,
             .uri = try alloc.dupeZ(u8, value.url),
@@ -235,8 +236,8 @@ fn destroyEntry(alloc: Allocator, entry: *Entry) void {
 }
 
 fn failRequest(self: *OpenURI, token: usize) ?*Entry {
-    self.mutex.lock();
-    defer self.mutex.unlock();
+    self.mutex.lockUncancelable(global.io());
+    defer self.mutex.unlock(global.io());
 
     if (!self.alive) return null;
 
@@ -422,8 +423,8 @@ fn requestCallback(
         return;
     }
 
-    self.mutex.lock();
-    defer self.mutex.unlock();
+    self.mutex.lockUncancelable(global.io());
+    defer self.mutex.unlock(global.io());
 
     if (!self.alive) return;
 
@@ -461,8 +462,8 @@ fn responseReceived(
         return;
     };
 
-    self.mutex.lock();
-    defer self.mutex.unlock();
+    self.mutex.lockUncancelable(global.io());
+    defer self.mutex.unlock(global.io());
 
     if (!self.alive) return;
 
@@ -534,22 +535,18 @@ fn cleanup(ud: ?*anyopaque) callconv(.c) c_int {
 
     const alloc = self.app.app.allocator();
 
-    self.mutex.lock();
-    defer self.mutex.unlock();
+    self.mutex.lockUncancelable(global.io());
+    defer self.mutex.unlock(global.io());
 
     self.cleanup_timer = null;
     if (!self.alive) return @intFromBool(glib.SOURCE_REMOVE);
 
-    const now = std.time.Instant.now() catch {
-        // `now()` should never fail, but if it does, don't crash, just return.
-        // This might cause a small memory leak in rare circumstances but it
-        // should get cleaned up the next time a URL is clicked.
-        return @intFromBool(glib.SOURCE_REMOVE);
-    };
-
     loop: while (true) {
         for (self.entries.entries.items(.value)) |entry| {
-            if (now.since(entry.start) > cleanup_timeout * std.time.ns_per_s) {
+            if (entry.start.untilNow(
+                global.io(),
+                .awake,
+            ).toSeconds() > cleanup_timeout) {
                 log.warn("open uri request timed out token={x}", .{entry.token});
                 self.unsubscribeFromResponse(entry);
                 _ = self.entries.swapRemove(entry.token);
diff --git a/src/apprt/gtk/post_fork.zig b/src/apprt/gtk/post_fork.zig
index ff0219508..d9b576fad 100644
--- a/src/apprt/gtk/post_fork.zig
+++ b/src/apprt/gtk/post_fork.zig
@@ -2,6 +2,7 @@ const std = @import("std");
 
 const gio = @import("gio");
 const glib = @import("glib");
+const global = @import("../../global.zig");
 
 const log = std.log.scoped(.gtk_post_fork);
 
@@ -85,12 +86,10 @@ pub fn postFork(cmd: *Command) Command.PostForkError!void {
         return;
     };
 
-    const start = std.time.Instant.now() catch unreachable;
+    const start: std.Io.Timestamp = .now(global.io(), .awake);
 
     loop: while (true) {
-        const now = std.time.Instant.now() catch unreachable;
-
-        if (now.since(start) > 250 * std.time.ns_per_ms) {
+        if (start.untilNow(global.io(), .awake).toMilliseconds() > 250) {
             if (cmd.rt_pre_exec_info.linux_cgroup_hard_fail) {
                 log.err("transition to new transient systemd scope {s} took too long", .{expected_cgroup});
                 return error.PostForkError;
@@ -116,6 +115,6 @@ pub fn postFork(cmd: *Command) Command.PostForkError!void {
             }
         }
 
-        std.Thread.sleep(25 * std.time.ns_per_ms);
+        std.Io.sleep(global.io(), .fromMilliseconds(25), .awake) catch unreachable;
     }
 }
diff --git a/src/apprt/gtk/pre_exec.zig b/src/apprt/gtk/pre_exec.zig
index 6f6a9ed51..a4eda4620 100644
--- a/src/apprt/gtk/pre_exec.zig
+++ b/src/apprt/gtk/pre_exec.zig
@@ -3,6 +3,7 @@ const std = @import("std");
 const log = std.log.scoped(.gtk_pre_exec);
 
 const configpkg = @import("../../config.zig");
+const global = @import("../../global.zig");
 
 const internal_os = @import("../../os/main.zig");
 const Command = @import("../../Command.zig");
@@ -47,12 +48,10 @@ pub fn preExec(cmd: *Command) ?u8 {
     var expected_cgroup_buf: [256]u8 = undefined;
     const expected_cgroup = cgroup.fmtScope(&expected_cgroup_buf, pid);
 
-    const start = std.time.Instant.now() catch unreachable;
+    const start: std.Io.Timestamp = .now(global.io(), .awake);
 
     while (true) {
-        const now = std.time.Instant.now() catch unreachable;
-
-        if (now.since(start) > 250 * std.time.ns_per_ms) {
+        if (start.untilNow(global.io(), .awake).toMilliseconds() > 250) {
             if (cmd.rt_pre_exec_info.linux_cgroup_hard_fail) {
                 log.err("transition to new transient systemd scope took too long", .{});
                 return 127;
@@ -74,7 +73,7 @@ pub fn preExec(cmd: *Command) ?u8 {
             if (std.mem.eql(u8, current_cgroup, expected_cgroup)) return null;
         }
 
-        std.Thread.sleep(25 * std.time.ns_per_ms);
+        std.Io.sleep(global.io(), .fromMilliseconds(25), .awake) catch unreachable;
     }
 
     return null;
diff --git a/src/apprt/gtk/winproto.zig b/src/apprt/gtk/winproto.zig
index d409d6c26..a6bc14d96 100644
--- a/src/apprt/gtk/winproto.zig
+++ b/src/apprt/gtk/winproto.zig
@@ -141,7 +141,7 @@ pub const Window = union(Protocol) {
         };
     }
 
-    pub fn addSubprocessEnv(self: *Window, env: *std.process.EnvMap) !void {
+    pub fn addSubprocessEnv(self: *Window, env: *std.process.Environ.Map) !void {
         switch (self.*) {
             inline else => |*v| try v.addSubprocessEnv(env),
         }
diff --git a/src/apprt/gtk/winproto/noop.zig b/src/apprt/gtk/winproto/noop.zig
index 950ee0f37..3b9a3fbc0 100644
--- a/src/apprt/gtk/winproto/noop.zig
+++ b/src/apprt/gtk/winproto/noop.zig
@@ -67,7 +67,7 @@ pub const Window = struct {
         return true;
     }
 
-    pub fn addSubprocessEnv(_: *Window, _: *std.process.EnvMap) !void {}
+    pub fn addSubprocessEnv(_: *Window, _: *std.process.Environ.Map) !void {}
 
     pub fn setUrgent(_: *Window, _: bool) !void {}
 };
diff --git a/src/apprt/gtk/winproto/wayland.zig b/src/apprt/gtk/winproto/wayland.zig
index 12c7fb8a2..a53035869 100644
--- a/src/apprt/gtk/winproto/wayland.zig
+++ b/src/apprt/gtk/winproto/wayland.zig
@@ -225,7 +225,7 @@ pub const Window = struct {
         };
     }
 
-    pub fn addSubprocessEnv(self: *Window, env: *std.process.EnvMap) !void {
+    pub fn addSubprocessEnv(self: *Window, env: *std.process.Environ.Map) !void {
         _ = self;
         _ = env;
     }
diff --git a/src/apprt/gtk/winproto/x11.zig b/src/apprt/gtk/winproto/x11.zig
index 8109959da..3ef33137a 100644
--- a/src/apprt/gtk/winproto/x11.zig
+++ b/src/apprt/gtk/winproto/x11.zig
@@ -317,7 +317,7 @@ pub const Window = struct {
         self.last_applied_decoration_hints = hints;
     }
 
-    pub fn addSubprocessEnv(self: *Window, env: *std.process.EnvMap) !void {
+    pub fn addSubprocessEnv(self: *Window, env: *std.process.Environ.Map) !void {
         var buf: [64]u8 = undefined;
         const window_id = try std.fmt.bufPrint(
             &buf,
diff --git a/src/apprt/ipc.zig b/src/apprt/ipc.zig
index dda794ae1..ade44da19 100644
--- a/src/apprt/ipc.zig
+++ b/src/apprt/ipc.zig
@@ -126,8 +126,12 @@ pub const Action = union(enum) {
     /// Sync with: ghostty_ipc_action_u
     pub const CValue = cvalue: {
         const key_fields = @typeInfo(Key).@"enum".fields;
-        var union_fields: [key_fields.len]std.builtin.Type.UnionField = undefined;
-        for (key_fields, 0..) |field, i| {
+
+        var names: [key_fields.len][]const u8 = undefined;
+        var types: [key_fields.len]type = undefined;
+        var attrs: [key_fields.len]std.builtin.Type.UnionField.Attributes = undefined;
+
+        for (key_fields, &names, &types, &attrs) |field, *name, *ty, *attr| {
             const action = @unionInit(Action, field.name, undefined);
             const Type = t: {
                 const Type = @TypeOf(@field(action, field.name));
@@ -135,20 +139,12 @@ pub const Action = union(enum) {
                 if (Type != void and @hasDecl(Type, "C")) break :t Type.C;
                 break :t Type;
             };
-
-            union_fields[i] = .{
-                .name = field.name,
-                .type = Type,
-                .alignment = @alignOf(Type),
-            };
+            name.* = field.name;
+            ty.* = Type;
+            attr.* = .{ .@"align" = @alignOf(Type) };
         }
 
-        break :cvalue @Type(.{ .@"union" = .{
-            .layout = .@"extern",
-            .tag_type = null,
-            .fields = &union_fields,
-            .decls = &.{},
-        } });
+        break :cvalue @Union(.@"extern", null, &names, &types, &attrs);
     };
 
     /// Sync with: ghostty_ipc_action_s
diff --git a/src/benchmark/ApcParser.zig b/src/benchmark/ApcParser.zig
index 73b7c57a2..8b5f883fd 100644
--- a/src/benchmark/ApcParser.zig
+++ b/src/benchmark/ApcParser.zig
@@ -12,6 +12,7 @@ const Allocator = std.mem.Allocator;
 const terminalpkg = @import("../terminal/main.zig");
 const Benchmark = @import("Benchmark.zig");
 const options = @import("options.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"apc-parser-bench");
 
@@ -19,7 +20,7 @@ opts: Options,
 stream: Stream,
 
 /// The file, opened in the setup function.
-data_f: ?std.fs.File = null,
+data_f: ?std.Io.File = null,
 
 pub const Options = struct {
     /// The data to read as a filepath. If this is "-" then
@@ -103,7 +104,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 fn teardown(ptr: *anyopaque) void {
     const self: *ApcParser = @ptrCast(@alignCast(ptr));
     if (self.data_f) |f| {
-        f.close();
+        f.close(global.io());
         self.data_f = null;
     }
 }
@@ -114,7 +115,7 @@ fn step(ptr: *anyopaque) Benchmark.Error!void {
     const f = self.data_f orelse return;
 
     var read_buf: [64 * 1024]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     const r = &f_reader.interface;
 
     // This buffer size matches the read buffer size used by the
diff --git a/src/benchmark/Benchmark.zig b/src/benchmark/Benchmark.zig
index 41c3695d4..d45ba181c 100644
--- a/src/benchmark/Benchmark.zig
+++ b/src/benchmark/Benchmark.zig
@@ -6,6 +6,7 @@ const builtin = @import("builtin");
 const assert = std.debug.assert;
 const macos = @import("macos");
 const build_config = @import("../build_config.zig");
+const global = @import("../global.zig");
 
 ptr: *anyopaque,
 vtable: VTable,
@@ -64,21 +65,23 @@ pub fn run(
         signpost.log.release();
     };
 
-    const start = std.time.Instant.now() catch return error.BenchmarkFailed;
+    const start: std.Io.Timestamp = .now(global.io(), .awake);
     while (true) {
         // Run our step function. If it fails, we return the error.
         try self.vtable.stepFn(self.ptr);
         result.iterations += 1;
 
         // Get our current monotonic time and check our exit conditions.
-        const now = std.time.Instant.now() catch return error.BenchmarkFailed;
+        const now: std.Io.Timestamp = .now(global.io(), .awake);
+        const elapsed = start.durationTo(now).nanoseconds;
+        assert(elapsed >= 0);
         const exit = switch (mode) {
             .once => true,
-            .duration => |ns| now.since(start) >= ns,
+            .duration => |ns| elapsed >= ns,
         };
 
         if (exit) {
-            result.duration = now.since(start);
+            result.duration = @as(u64, @intCast(std.math.clamp(elapsed, 0, std.math.maxInt(u64))));
             return result;
         }
     }
diff --git a/src/benchmark/CApi.zig b/src/benchmark/CApi.zig
index 3bef8b269..c98406713 100644
--- a/src/benchmark/CApi.zig
+++ b/src/benchmark/CApi.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 const cli = @import("cli.zig");
-const state = &@import("../global.zig").state;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.benchmark);
 
@@ -19,7 +19,7 @@ export fn ghostty_benchmark_cli(
     };
 
     cli.mainAction(
-        state.alloc,
+        global.alloc(),
         action,
         .{ .string = std.mem.sliceTo(args, 0) },
     ) catch |err| {
diff --git a/src/benchmark/CodepointWidth.zig b/src/benchmark/CodepointWidth.zig
index 30d3f91e7..d0c6b8089 100644
--- a/src/benchmark/CodepointWidth.zig
+++ b/src/benchmark/CodepointWidth.zig
@@ -14,13 +14,14 @@ const options = @import("options.zig");
 const UTF8Decoder = @import("../terminal/UTF8Decoder.zig");
 const simd = @import("../simd/main.zig");
 const table = @import("../unicode/main.zig").table;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"terminal-stream-bench");
 
 opts: Options,
 
 /// The file, opened in the setup function.
-data_f: ?std.fs.File = null,
+data_f: ?std.Io.File = null,
 
 pub const Options = struct {
     /// The type of codepoint width calculation to use.
@@ -93,7 +94,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 fn teardown(ptr: *anyopaque) void {
     const self: *CodepointWidth = @ptrCast(@alignCast(ptr));
     if (self.data_f) |f| {
-        f.close();
+        f.close(global.io());
         self.data_f = null;
     }
 }
@@ -114,7 +115,7 @@ fn stepWcwidth(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var d: UTF8Decoder = .{};
@@ -141,7 +142,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var d: UTF8Decoder = .{};
@@ -173,7 +174,7 @@ fn stepSimd(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var d: UTF8Decoder = .{};
diff --git a/src/benchmark/GraphemeBreak.zig b/src/benchmark/GraphemeBreak.zig
index 8278c5c2f..8e5236fe1 100644
--- a/src/benchmark/GraphemeBreak.zig
+++ b/src/benchmark/GraphemeBreak.zig
@@ -11,13 +11,14 @@ const options = @import("options.zig");
 const UTF8Decoder = @import("../terminal/UTF8Decoder.zig");
 const unicode = @import("../unicode/main.zig");
 const uucode = @import("uucode");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"terminal-stream-bench");
 
 opts: Options,
 
 /// The file, opened in the setup function.
-data_f: ?std.fs.File = null,
+data_f: ?std.Io.File = null,
 
 pub const Options = struct {
     /// The type of codepoint width calculation to use.
@@ -82,7 +83,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 fn teardown(ptr: *anyopaque) void {
     const self: *GraphemeBreak = @ptrCast(@alignCast(ptr));
     if (self.data_f) |f| {
-        f.close();
+        f.close(global.io());
         self.data_f = null;
     }
 }
@@ -92,7 +93,7 @@ fn stepNoop(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var d: UTF8Decoder = .{};
@@ -115,7 +116,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var d: UTF8Decoder = .{};
diff --git a/src/benchmark/IsSymbol.zig b/src/benchmark/IsSymbol.zig
index 4fbffd1ec..c99bc9ca2 100644
--- a/src/benchmark/IsSymbol.zig
+++ b/src/benchmark/IsSymbol.zig
@@ -11,13 +11,14 @@ const options = @import("options.zig");
 const UTF8Decoder = @import("../terminal/UTF8Decoder.zig");
 const uucode = @import("uucode");
 const symbols_table = @import("../unicode/symbols_table.zig").table;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"is-symbol-bench");
 
 opts: Options,
 
 /// The file, opened in the setup function.
-data_f: ?std.fs.File = null,
+data_f: ?std.Io.File = null,
 
 pub const Options = struct {
     /// Which test to run.
@@ -80,7 +81,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 fn teardown(ptr: *anyopaque) void {
     const self: *IsSymbol = @ptrCast(@alignCast(ptr));
     if (self.data_f) |f| {
-        f.close();
+        f.close(global.io());
         self.data_f = null;
     }
 }
@@ -90,7 +91,7 @@ fn stepUucode(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var d: UTF8Decoder = .{};
@@ -117,7 +118,7 @@ fn stepTable(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var d: UTF8Decoder = .{};
diff --git a/src/benchmark/OscParser.zig b/src/benchmark/OscParser.zig
index d4b416de8..9b21c37ab 100644
--- a/src/benchmark/OscParser.zig
+++ b/src/benchmark/OscParser.zig
@@ -9,11 +9,12 @@ const Benchmark = @import("Benchmark.zig");
 const options = @import("options.zig");
 const Parser = @import("../terminal/osc.zig").Parser;
 const log = std.log.scoped(.@"osc-parser-bench");
+const global = @import("../global.zig");
 
 opts: Options,
 
 /// The file, opened in the setup function.
-data_f: ?std.fs.File = null,
+data_f: ?std.Io.File = null,
 
 parser: Parser,
 
@@ -70,7 +71,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 fn teardown(ptr: *anyopaque) void {
     const self: *OscParser = @ptrCast(@alignCast(ptr));
     if (self.data_f) |f| {
-        f.close();
+        f.close(global.io());
         self.data_f = null;
     }
 }
@@ -80,7 +81,7 @@ fn step(ptr: *anyopaque) Benchmark.Error!void {
 
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var r = f.reader(&read_buf);
+    var r = f.reader(global.io(), &read_buf);
 
     var osc_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
     while (true) {
diff --git a/src/benchmark/PageCompression.zig b/src/benchmark/PageCompression.zig
index 21153659e..23ecf0bf2 100644
--- a/src/benchmark/PageCompression.zig
+++ b/src/benchmark/PageCompression.zig
@@ -67,6 +67,8 @@ const options = @import("options.zig");
 const compress = @import("../terminal/compress.zig");
 const CompressedPage = compress.Page;
 const lz4 = compress.lz4;
+const compat_file = @import("../lib/compat/file.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"page-compression-bench");
 
@@ -210,9 +212,9 @@ fn setupData(self: *PageCompression) !void {
         return error.InvalidRetainedPages;
 
     const data_file = try options.dataFile(self.opts.data) orelse return;
-    defer data_file.close();
+    defer data_file.close(global.io());
 
-    self.data = try data_file.readToEndAlloc(self.alloc, max_data_size);
+    self.data = try compat_file.readToEndAlloc(data_file, self.alloc, max_data_size);
     errdefer {
         self.alloc.free(self.data);
         self.data = &.{};
diff --git a/src/benchmark/ScreenClone.zig b/src/benchmark/ScreenClone.zig
index 5176ce26c..9b2012cc1 100644
--- a/src/benchmark/ScreenClone.zig
+++ b/src/benchmark/ScreenClone.zig
@@ -11,6 +11,7 @@ const terminalpkg = @import("../terminal/main.zig");
 const Benchmark = @import("Benchmark.zig");
 const options = @import("options.zig");
 const Terminal = terminalpkg.Terminal;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"terminal-stream-bench");
 
@@ -79,7 +80,7 @@ pub fn create(
 
     ptr.* = .{
         .opts = opts,
-        .terminal = try .init(alloc, .{
+        .terminal = try .init(global.io(), alloc, .{
             .rows = opts.@"terminal-rows",
             .cols = opts.@"terminal-cols",
         }),
@@ -122,7 +123,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
     s.nextSlice("hello");
 
     // Setup our terminal state
-    const data_f: std.fs.File = (options.dataFile(
+    const data_f: std.Io.File = (options.dataFile(
         self.opts.data,
     ) catch |err| {
         log.warn("error opening data file err={}", .{err});
@@ -133,7 +134,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
     defer stream.deinit();
 
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = data_f.reader(&read_buf);
+    var f_reader = data_f.reader(global.io(), &read_buf);
     const r = &f_reader.interface;
 
     var buf: [4096]u8 = undefined;
@@ -171,6 +172,7 @@ fn stepClone(ptr: *anyopaque) Benchmark.Error!void {
     for (0..1000) |_| {
         const s: *terminalpkg.Screen = self.terminal.screens.active;
         const copy = s.clone(
+            s.io,
             s.alloc,
             .{ .viewport = .{} },
             null,
diff --git a/src/benchmark/ScrollbackCompression.zig b/src/benchmark/ScrollbackCompression.zig
index 40ec20f48..3968427b4 100644
--- a/src/benchmark/ScrollbackCompression.zig
+++ b/src/benchmark/ScrollbackCompression.zig
@@ -74,6 +74,7 @@ const Benchmark = @import("Benchmark.zig");
 const options = @import("options.zig");
 const PageList = terminalpkg.PageList;
 const Terminal = terminalpkg.Terminal;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"scrollback-compression-bench");
 
@@ -134,7 +135,7 @@ pub fn create(
 
     ptr.* = .{
         .opts = opts,
-        .terminal = try .init(alloc, .{
+        .terminal = try .init(global.io(), alloc, .{
             .rows = opts.@"terminal-rows",
             .cols = opts.@"terminal-cols",
             .max_scrollback = opts.@"max-scrollback",
@@ -182,13 +183,13 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 /// terminal-stream benchmark. Parser and file IO costs remain in setup.
 fn loadCorpus(self: *ScrollbackCompression) !void {
     const data_file = try options.dataFile(self.opts.data) orelse return;
-    defer data_file.close();
+    defer data_file.close(global.io());
 
     var stream = self.terminal.vtStream();
     defer stream.deinit();
 
     var read_buf: [64 * 1024]u8 align(std.atomic.cache_line) = undefined;
-    var file_reader = data_file.reader(&read_buf);
+    var file_reader = data_file.reader(global.io(), &read_buf);
     const reader = &file_reader.interface;
 
     var buf: [64 * 1024]u8 = undefined;
diff --git a/src/benchmark/TerminalParser.zig b/src/benchmark/TerminalParser.zig
index 78c933121..d393301c3 100644
--- a/src/benchmark/TerminalParser.zig
+++ b/src/benchmark/TerminalParser.zig
@@ -7,13 +7,14 @@ const Allocator = std.mem.Allocator;
 const terminalpkg = @import("../terminal/main.zig");
 const Benchmark = @import("Benchmark.zig");
 const options = @import("options.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"terminal-stream-bench");
 
 opts: Options,
 
 /// The file, opened in the setup function.
-data_f: ?std.fs.File = null,
+data_f: ?std.Io.File = null,
 
 pub const Options = struct {
     /// The data to read as a filepath. If this is "-" then
@@ -61,7 +62,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 fn teardown(ptr: *anyopaque) void {
     const self: *TerminalParser = @ptrCast(@alignCast(ptr));
     if (self.data_f) |f| {
-        f.close();
+        f.close(global.io());
         self.data_f = null;
     }
 }
@@ -76,7 +77,7 @@ fn step(ptr: *anyopaque) Benchmark.Error!void {
     // aren't currently IO bound.
     const f = self.data_f orelse return;
     var read_buf: [4096]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    var f_reader = f.reader(global.io(), &read_buf);
     var r = &f_reader.interface;
 
     var p: terminalpkg.Parser = .init();
diff --git a/src/benchmark/TerminalStream.zig b/src/benchmark/TerminalStream.zig
index a5302005b..a521c5b7a 100644
--- a/src/benchmark/TerminalStream.zig
+++ b/src/benchmark/TerminalStream.zig
@@ -19,6 +19,7 @@ const Benchmark = @import("Benchmark.zig");
 const options = @import("options.zig");
 const Terminal = terminalpkg.Terminal;
 const Stream = terminalpkg.TerminalStream;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"terminal-stream-bench");
 
@@ -27,7 +28,7 @@ terminal: Terminal,
 stream: Stream,
 
 /// The file, opened in the setup function.
-data_f: ?std.fs.File = null,
+data_f: ?std.Io.File = null,
 
 pub const Options = struct {
     /// The size of the terminal. This affects benchmarking when
@@ -54,7 +55,7 @@ pub fn create(
 
     ptr.* = .{
         .opts = opts,
-        .terminal = try .init(alloc, .{
+        .terminal = try .init(global.io(), alloc, .{
             .rows = opts.@"terminal-rows",
             .cols = opts.@"terminal-cols",
         }),
@@ -97,7 +98,7 @@ fn setup(ptr: *anyopaque) Benchmark.Error!void {
 fn teardown(ptr: *anyopaque) void {
     const self: *TerminalStream = @ptrCast(@alignCast(ptr));
     if (self.data_f) |f| {
-        f.close();
+        f.close(global.io());
         self.data_f = null;
     }
 }
@@ -112,8 +113,10 @@ fn step(ptr: *anyopaque) Benchmark.Error!void {
     // aren't currently IO bound.
     const f = self.data_f orelse return;
 
-    var read_buf: [64 * 1024]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(&read_buf);
+    // Unbuffered: readSliceShort below reads directly into `buf`,
+    // avoiding a per-chunk memcpy through an intermediate reader
+    // buffer that would pollute the measurement.
+    var f_reader = f.reader(global.io(), &.{});
     const r = &f_reader.interface;
 
     // This buffer size matches the read buffer size used by the
diff --git a/src/benchmark/cli.zig b/src/benchmark/cli.zig
index dc4d7b8f4..19db37a3d 100644
--- a/src/benchmark/cli.zig
+++ b/src/benchmark/cli.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
 const cli = @import("../cli.zig");
+const global = @import("../global.zig");
 
 /// The available actions for the CLI. This is the list of available
 /// benchmarks. View docs for each individual one in the predictably
@@ -44,19 +45,20 @@ pub const Action = enum {
 };
 
 /// An entrypoint for the benchmark CLI.
-pub fn main() !void {
+pub fn main(minimal: std.process.Init.Minimal) !void {
+    try global.init(.{ .tool = minimal });
     const alloc = std.heap.c_allocator;
-    const action_ = try cli.action.detectArgs(Action, alloc);
+    const action_ = try cli.action.detectArgs(Action, alloc, minimal.args);
     const action = action_ orelse return error.NoAction;
-    try mainAction(alloc, action, .cli);
+    try mainAction(alloc, action, .{ .cli = minimal.args });
 }
 
 /// Arguments that can be passed to the benchmark.
 pub const Args = union(enum) {
     /// The arguments passed to the CLI via argc/argv.
-    cli,
+    cli: std.process.Args,
 
-    /// Simple string arguments, parsed via std.process.ArgIteratorGeneral.
+    /// Simple string arguments, parsed via ArgIteratorGeneral.
     string: []const u8,
 };
 
@@ -83,13 +85,13 @@ fn mainActionImpl(
     var opts: Options = .{};
     defer if (@hasDecl(Options, "deinit")) opts.deinit();
     switch (args) {
-        .cli => {
-            var iter = try cli.args.argsIterator(alloc);
+        .cli => |process_args| {
+            var iter = try cli.args.argsIterator(alloc, process_args);
             defer iter.deinit();
             try cli.args.parse(Options, alloc, &opts, &iter);
         },
         .string => |str| {
-            var iter = try std.process.ArgIteratorGeneral(.{}).init(
+            var iter = try std.process.Args.IteratorGeneral(.{}).init(
                 alloc,
                 str,
             );
diff --git a/src/benchmark/options.zig b/src/benchmark/options.zig
index 049e80f48..9322818d4 100644
--- a/src/benchmark/options.zig
+++ b/src/benchmark/options.zig
@@ -1,20 +1,21 @@
 //! This file contains helpers for CLI options.
 
 const std = @import("std");
+const global = @import("../global.zig");
 
 /// Returns the data file for the given path in a way that is consistent
 /// across our CLI. If the path is not set then no file is returned.
 /// If the path is "-", then we will return stdin. If the path is
 /// a file then we will open and return the handle.
-pub fn dataFile(path_: ?[]const u8) !?std.fs.File {
+pub fn dataFile(path_: ?[]const u8) !?std.Io.File {
     const path = path_ orelse return null;
 
     // Stdin
     if (std.mem.eql(u8, path, "-")) return .stdin();
 
     // Normal file
-    const file = try std.fs.cwd().openFile(path, .{});
-    errdefer file.close();
+    const file = try std.Io.Dir.cwd().openFile(global.io(), path, .{});
+    errdefer file.close(global.io());
 
     return file;
 }
diff --git a/src/build/Config.zig b/src/build/Config.zig
index 0a9947317..43db20971 100644
--- a/src/build/Config.zig
+++ b/src/build/Config.zig
@@ -43,7 +43,7 @@ lib_version: std.SemanticVersion = .{ .major = 0, .minor = 0, .patch = 0 },
 /// Binary properties
 pie: bool = false,
 strip: bool = false,
-patch_rpath: ?[]const u8 = null,
+patchelf: ?PatchElf = null,
 
 /// Artifacts
 flatpak: bool = false,
@@ -67,7 +67,7 @@ emit_unicode_table_gen: bool = false,
 is_dep: bool = false,
 
 /// Environmental properties
-env: std.process.EnvMap,
+env: *const std.process.Environ.Map,
 
 pub fn init(b: *std.Build, appVersion: []const u8, libVersion: []const u8) !Config {
     // Setup our standard Zig target and optimize options, i.e.
@@ -124,10 +124,10 @@ pub fn init(b: *std.Build, appVersion: []const u8, libVersion: []const u8) !Conf
     // defaults.
     const gtk_targets = gtk.targets(b);
 
-    // We use env vars throughout the build so we grab them immediately here.
-    var env = try std.process.getEnvMap(b.allocator);
-    errdefer env.deinit();
+    // Grab the environment from build state
+    const env = &b.graph.environ_map;
 
+    // We use env vars throughout the build so we grab them immediately here.
     var config: Config = .{
         .optimize = optimize,
         .target = target,
@@ -312,24 +312,38 @@ pub fn init(b: *std.Build, appVersion: []const u8, libVersion: []const u8) !Conf
     //---------------------------------------------------------------
     // Binary Properties
 
-    // On NixOS, the built binary from `zig build` needs to patch the rpath
-    // into the built binary for it to be portable across the NixOS system
-    // it was built for. We default this to true if we can detect we're in
-    // a Nix shell and have LD_LIBRARY_PATH set.
-    config.patch_rpath = b.option(
-        []const u8,
-        "patch-rpath",
-        "Inject the LD_LIBRARY_PATH as the rpath in the built binary. " ++
-            "This defaults to LD_LIBRARY_PATH if we're in a Nix shell environment on NixOS.",
-    ) orelse patch_rpath: {
-        // We only do the patching if we're targeting our own CPU and its Linux.
-        if (!(target.result.os.tag == .linux) or !target.query.isNativeCpu()) break :patch_rpath null;
-
-        // If we're in a nix shell we default to doing this.
-        // Note: we purposely never deinit envmap because we leak the strings
-        if (env.get("IN_NIX_SHELL") == null) break :patch_rpath null;
-        break :patch_rpath env.get("LD_LIBRARY_PATH");
-    };
+    // On NixOS, the built binary from `zig build` needs to patch the interp
+    // and rpath into the built binary for it to be portable across the NixOS
+    // system it was built for. We default this to true if we can detect we're
+    // in a Nix shell.
+    //
+    // Note that this option is only available on Linux and if building
+    // natively.
+    //
+    // NOTE: Zig does now have an option to pass in the dynamic linker
+    // (-Ddynamic-linker), but it does seem to have some issues in 0.16.0 that
+    // may be fixed in 0.17.0. We may want to revisit this afterwards; although
+    // I'm not too sure if that helps to clean up rpath, this may just be the
+    // better option. See https://codeberg.org/ziglang/zig/issues/31760.
+    if ((target.result.os.tag == .linux) and target.query.isNativeCpu()) {
+        const in_nix_shell = env.get("IN_NIX_SHELL") != null;
+        if (b.option(
+            bool,
+            "patchelf",
+            "Patch interpreter and rpath in the built binary (default if IN_NIX_SHELL is set)",
+        ) orelse in_nix_shell) {
+            var patchelf: PatchElf = .{};
+            if (b.findProgram(&.{"ld.so"}, &.{})) |ld_so| {
+                patchelf.interp = std.Io.Dir.realPathFileAbsoluteAlloc(b.graph.io, ld_so, b.allocator) catch null;
+            } else |_| {}
+            if (env.get("LD_LIBRARY_PATH")) |ld_library_path| {
+                patchelf.rpath = if (ld_library_path.len > 0) ld_library_path else null;
+            }
+            if (patchelf.interp != null or patchelf.rpath != null) {
+                config.patchelf = patchelf;
+            }
+        }
+    }
 
     config.pie = b.option(
         bool,
@@ -401,7 +415,7 @@ pub fn init(b: *std.Build, appVersion: []const u8, libVersion: []const u8) !Conf
         if (system_package) break :emit_docs true;
 
         // We only default to true if we can find pandoc.
-        const path = expandPath(b.allocator, "pandoc") catch
+        const path = expandPath(b.graph.io, b.allocator, &b.graph.environ_map, "pandoc") catch
             break :emit_docs false;
         defer if (path) |p| b.allocator.free(p);
         break :emit_docs path != null;
@@ -450,7 +464,7 @@ pub fn init(b: *std.Build, appVersion: []const u8, libVersion: []const u8) !Conf
         if (config.emit_lib_vt) {
             // In lib-vt mode default to whether xcodebuild is available,
             // since xcodebuild is required to produce the XCFramework.
-            const path = expandPath(b.allocator, "xcodebuild") catch
+            const path = expandPath(b.graph.io, b.allocator, &b.graph.environ_map, "xcodebuild") catch
                 break :emit_xcfw false;
             defer if (path) |p| b.allocator.free(p);
             break :emit_xcfw path != null;
@@ -522,6 +536,27 @@ pub fn init(b: *std.Build, appVersion: []const u8, libVersion: []const u8) !Conf
     return config;
 }
 
+const PatchElf = struct {
+    interp: ?[]const u8 = null,
+    rpath: ?[]const u8 = null,
+};
+
+/// Add a patchelf step for the supplied `artifact`, depending on the supplied
+/// `step`, if `patchelf` is present in the config.
+pub fn addPatchElf(self: *const Config, artifact: *std.Build.Step.Compile, step: *std.Build.Step) void {
+    const b = artifact.step.owner;
+    std.debug.assert(b == step.owner);
+
+    if (self.patchelf) |patchelf| {
+        const run = std.Build.Step.Run.create(b, "patchelf");
+        run.addArgs(&.{"patchelf"});
+        if (patchelf.interp) |interp| run.addArgs(&.{ "--set-interpreter", interp });
+        if (patchelf.rpath) |rpath| run.addArgs(&.{ "--set-rpath", rpath });
+        run.addArtifactArg(artifact);
+        step.dependOn(&run.step);
+    }
+}
+
 /// Configure the build options with our values.
 pub fn addOptions(self: *const Config, step: *std.Build.Step.Options) !void {
     // We need to break these down individual because addOption doesn't
@@ -570,7 +605,11 @@ pub fn addOptions(self: *const Config, step: *std.Build.Step.Options) !void {
 
 /// Returns the build options for the terminal module. This assumes a
 /// Ghostty executable being built. Callers should modify this as needed.
-pub fn terminalOptions(self: *const Config, artifact: TerminalBuildOptions.Artifact) TerminalBuildOptions {
+pub fn terminalOptions(
+    self: *const Config,
+    artifact: TerminalBuildOptions.Artifact,
+    optimize: std.builtin.OptimizeMode,
+) TerminalBuildOptions {
     return .{
         .artifact = artifact,
         .simd = self.simd,
@@ -580,7 +619,7 @@ pub fn terminalOptions(self: *const Config, artifact: TerminalBuildOptions.Artif
             .ghostty => self.version,
             .lib => self.lib_version,
         },
-        .slow_runtime_safety = switch (self.optimize) {
+        .slow_runtime_safety = switch (optimize) {
             .Debug => true,
             .ReleaseSafe,
             .ReleaseSmall,
@@ -591,7 +630,7 @@ pub fn terminalOptions(self: *const Config, artifact: TerminalBuildOptions.Artif
 }
 
 /// Returns a baseline CPU target retaining all the other CPU configs.
-pub fn baselineTarget(self: *const Config) std.Build.ResolvedTarget {
+pub fn baselineTarget(self: *const Config, io: std.Io) std.Build.ResolvedTarget {
     // Set our cpu model as baseline. There may need to be other modifications
     // we need to make such as resetting CPU features but for now this works.
     var q = self.target.query;
@@ -601,7 +640,7 @@ pub fn baselineTarget(self: *const Config) std.Build.ResolvedTarget {
     // handle the native case.
     return .{
         .query = q,
-        .result = std.zig.system.resolveTargetQuery(q) catch
+        .result = std.zig.system.resolveTargetQuery(io, q) catch
             @panic("unable to resolve baseline query"),
     };
 }
@@ -630,6 +669,17 @@ pub fn fromOptions() Config {
     };
 }
 
+/// Whether release artifacts should omit frame pointers.
+///
+/// Stripped release builds omit them in general, but we always keep frame
+/// pointers on Apple platforms: the Apple arm64 ABI expects x29 to
+/// be a valid frame pointer and Apple's profiling and crash reporting
+/// tools rely on it for backtraces.
+pub fn omitFramePointer(self: *const Config) bool {
+    if (self.target.result.os.tag.isDarwin()) return false;
+    return self.strip;
+}
+
 /// Returns the minimum OS version for the given OS tag. This shouldn't
 /// be used generally, it should only be used for Darwin-based OS currently.
 pub fn osVersionMin(tag: std.Target.Os.Tag) ?std.Target.Query.OsVersion {
diff --git a/src/build/GhosttyBench.zig b/src/build/GhosttyBench.zig
index 27dda8809..fbf8029d2 100644
--- a/src/build/GhosttyBench.zig
+++ b/src/build/GhosttyBench.zig
@@ -23,9 +23,9 @@ pub fn init(
                 // We always want our datagen to be fast because it
                 // takes awhile to run.
                 .optimize = .ReleaseFast,
+                .link_libc = true,
             }),
         });
-        exe.linkLibC();
         _ = try deps.add(exe);
         try steps.append(b.allocator, exe);
     }
@@ -39,9 +39,9 @@ pub fn init(
                 .target = deps.config.target,
                 // We always want our benchmarks to be in release mode.
                 .optimize = .ReleaseFast,
+                .link_libc = true,
             }),
         });
-        exe.linkLibC();
         _ = try deps.add(exe);
         try steps.append(b.allocator, exe);
     }
diff --git a/src/build/GhosttyDist.zig b/src/build/GhosttyDist.zig
index 448047f4b..fe8b863fb 100644
--- a/src/build/GhosttyDist.zig
+++ b/src/build/GhosttyDist.zig
@@ -237,11 +237,11 @@ pub const Resource = struct {
 
     /// Returns true if the dist path exists at build time.
     pub fn exists(self: *const Resource, b: *std.Build) bool {
-        if (b.build_root.handle.access(self.dist, .{})) {
+        if (b.build_root.handle.access(b.graph.io, self.dist, .{})) {
             // If we have a ".git" directory then we're a git checkout
             // and we never want to use the dist path. This shouldn't happen
             // so show a warning to the user.
-            if (b.build_root.handle.access(".git", .{})) {
+            if (b.build_root.handle.access(b.graph.io, ".git", .{})) {
                 std.log.warn(
                     "dist resource '{s}' should not be in a git checkout",
                     .{self.dist},
diff --git a/src/build/GhosttyDocs.zig b/src/build/GhosttyDocs.zig
index cd75fc061..2b207f237 100644
--- a/src/build/GhosttyDocs.zig
+++ b/src/build/GhosttyDocs.zig
@@ -50,7 +50,7 @@ pub fn init(
         generate_markdown.root_module.addOptions("build_options", generate_markdown_options);
 
         const generate_markdown_step = b.addRunArtifact(generate_markdown);
-        const markdown_output = generate_markdown_step.captureStdOut();
+        const markdown_output = generate_markdown_step.captureStdOut(.{});
 
         try steps.append(b.allocator, &b.addInstallFile(
             markdown_output,
@@ -68,7 +68,7 @@ pub fn init(
         generate_html.addFileArg(markdown_output);
 
         try steps.append(b.allocator, &b.addInstallFile(
-            generate_html.captureStdOut(),
+            generate_html.captureStdOut(.{}),
             "share/ghostty/doc/" ++ manpage.name ++ "." ++ manpage.section ++ ".html",
         ).step);
 
@@ -83,7 +83,7 @@ pub fn init(
         generate_manpage.addFileArg(markdown_output);
 
         try steps.append(b.allocator, &b.addInstallFile(
-            generate_manpage.captureStdOut(),
+            generate_manpage.captureStdOut(.{}),
             "share/man/man" ++ manpage.section ++ "/" ++ manpage.name ++ "." ++ manpage.section,
         ).step);
     }
diff --git a/src/build/GhosttyExe.zig b/src/build/GhosttyExe.zig
index caa564bf0..22f39b7b3 100644
--- a/src/build/GhosttyExe.zig
+++ b/src/build/GhosttyExe.zig
@@ -18,7 +18,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
             .target = cfg.target,
             .optimize = cfg.optimize,
             .strip = cfg.strip,
-            .omit_frame_pointer = cfg.strip,
+            .omit_frame_pointer = cfg.omitFramePointer(),
             .unwind_tables = if (cfg.strip) .none else .sync,
         }),
         // Crashes on x86_64 self-hosted on 0.15.1
@@ -36,21 +36,14 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
     // Check for possible issues
     try checkNixShell(exe, cfg);
 
-    // Patch our rpath if that option is specified.
-    if (cfg.patch_rpath) |rpath| {
-        if (rpath.len > 0) {
-            const run = std.Build.Step.Run.create(b, "patchelf rpath");
-            run.addArgs(&.{ "patchelf", "--set-rpath", rpath });
-            run.addArtifactArg(exe);
-            install_step.step.dependOn(&run.step);
-        }
-    }
+    // Add patchelf step if that option is specified.
+    cfg.addPatchElf(exe, &install_step.step);
 
     // OS-specific
     switch (cfg.target.result.os.tag) {
         .windows => {
             exe.subsystem = .Windows;
-            exe.addWin32ResourceFile(.{
+            exe.root_module.addWin32ResourceFile(.{
                 .file = b.path("dist/windows/ghostty.rc"),
             });
         },
@@ -85,7 +78,7 @@ fn checkNixShell(exe: *std.Build.Step.Compile, cfg: *const Config) !void {
     if (!cfg.target.query.isNativeOs()) return;
 
     // Verify we're in NixOS
-    std.fs.accessAbsolute("/etc/NIXOS", .{}) catch return;
+    std.Io.Dir.accessAbsolute(exe.step.owner.graph.io, "/etc/NIXOS", .{}) catch return;
 
     // If we're in a nix shell, not a problem
     if (cfg.env.get("IN_NIX_SHELL") != null) return;
diff --git a/src/build/GhosttyFrameData.zig b/src/build/GhosttyFrameData.zig
index 8469759f9..be61f029f 100644
--- a/src/build/GhosttyFrameData.zig
+++ b/src/build/GhosttyFrameData.zig
@@ -40,16 +40,16 @@ pub fn distResources(b: *std.Build) struct {
         .name = "framegen",
         .root_module = b.createModule(.{
             .target = b.graph.host,
+            .link_libc = true,
         }),
     });
-    exe.addCSourceFile(.{
+    exe.root_module.addCSourceFile(.{
         .file = b.path("src/build/framegen/main.c"),
         .flags = &.{},
     });
-    exe.linkLibC();
 
     if (b.systemIntegrationOption("zlib", .{})) {
-        exe.linkSystemLibrary2("zlib", .{
+        exe.root_module.linkSystemLibrary("zlib", .{
             .preferred_link_mode = .dynamic,
             .search_strategy = .mode_first,
         });
@@ -58,7 +58,7 @@ pub fn distResources(b: *std.Build) struct {
             .target = b.graph.host,
             .optimize = .ReleaseFast,
         })) |zlib_dep| {
-            exe.linkLibrary(zlib_dep.artifact("z"));
+            exe.root_module.linkLibrary(zlib_dep.artifact("z"));
         }
     }
 
diff --git a/src/build/GhosttyI18n.zig b/src/build/GhosttyI18n.zig
index 0874676cb..434c59a5d 100644
--- a/src/build/GhosttyI18n.zig
+++ b/src/build/GhosttyI18n.zig
@@ -34,7 +34,7 @@ pub fn init(b: *std.Build, cfg: *const Config) !GhosttyI18n {
         msgfmt.addFileArg(b.path("po/" ++ locale ++ ".po"));
 
         try steps.append(b.allocator, &b.addInstallFile(
-            msgfmt.captureStdOut(),
+            msgfmt.captureStdOut(.{}),
             std.fmt.comptimePrint(
                 "share/locale/{s}/LC_MESSAGES/{s}.mo",
                 .{ target_locale, domain },
@@ -103,14 +103,15 @@ fn createUpdateStep(b: *std.Build) !*std.Build.Step {
         }
 
         var gtk_dir = try b.build_root.handle.openDir(
+            b.graph.io,
             "src/apprt/gtk",
             .{ .iterate = true },
         );
-        defer gtk_dir.close();
+        defer gtk_dir.close(b.graph.io);
 
         var walk = try gtk_dir.walk(b.allocator);
         defer walk.deinit();
-        while (try walk.next()) |src| {
+        while (try walk.next(b.graph.io)) |src| {
             switch (src.kind) {
                 .file => if (!std.mem.endsWith(
                     u8,
@@ -178,15 +179,15 @@ fn createUpdateStep(b: *std.Build) !*std.Build.Step {
     xgettext_merge.addFileArg(gtk_pot);
     const usf = b.addUpdateSourceFiles();
     usf.addCopyFileToSource(
-        xgettext_merge.captureStdOut(),
+        xgettext_merge.captureStdOut(.{}),
         "po/" ++ domain ++ ".pot",
     );
 
     inline for (locales) |locale| {
         const msgmerge = b.addSystemCommand(&.{ "msgmerge", "--quiet", "--no-fuzzy-matching" });
         msgmerge.addFileArg(b.path("po/" ++ locale ++ ".po"));
-        msgmerge.addFileArg(xgettext_merge.captureStdOut());
-        usf.addCopyFileToSource(msgmerge.captureStdOut(), "po/" ++ locale ++ ".po");
+        msgmerge.addFileArg(xgettext_merge.captureStdOut(.{}));
+        usf.addCopyFileToSource(msgmerge.captureStdOut(.{}), "po/" ++ locale ++ ".po");
     }
 
     return &usf.step;
diff --git a/src/build/GhosttyLib.zig b/src/build/GhosttyLib.zig
index b762da8bb..529bb2821 100644
--- a/src/build/GhosttyLib.zig
+++ b/src/build/GhosttyLib.zig
@@ -1,9 +1,11 @@
 const GhosttyLib = @This();
 
 const std = @import("std");
+const builtin = @import("builtin");
 const RunStep = std.Build.Step.Run;
 const CombineArchivesStep = @import("CombineArchivesStep.zig");
 const Config = @import("Config.zig");
+const LibsystemOverrideStep = @import("LibsystemOverrideStep.zig");
 const SharedDeps = @import("SharedDeps.zig");
 const LipoStep = @import("LipoStep.zig");
 
@@ -27,14 +29,14 @@ pub fn initStatic(
             .target = deps.config.target,
             .optimize = deps.config.optimize,
             .strip = deps.config.strip,
-            .omit_frame_pointer = deps.config.strip,
+            .omit_frame_pointer = deps.config.omitFramePointer(),
             .unwind_tables = if (deps.config.strip) .none else .sync,
+            .link_libc = true,
         }),
 
         // Fails on self-hosted x86_64 on macOS
         .use_llvm = true,
     });
-    lib.linkLibC();
 
     // These must be bundled since we're compiling into a static lib.
     // Otherwise, you get undefined symbol errors.
@@ -57,9 +59,19 @@ pub fn initStatic(
     const combined = CombineArchivesStep.create(b, deps.config.target, "ghostty-internal", lib_list.items);
     combined.step.dependOn(&lib.step);
 
+    // On Darwin, prefer libSystem's libc/libm over the bundled
+    // compiler-rt for consumers of this archive. See
+    // libsystem_override.sh for details. This is a no-op elsewhere.
+    const override = LibsystemOverrideStep.create(
+        b,
+        deps.config.target,
+        combined.output,
+        "libghostty-internal.a",
+    );
+
     return .{
-        .step = combined.step,
-        .output = combined.output,
+        .step = override.step orelse combined.step,
+        .output = override.output,
 
         // Static libraries cannot have dSYMs because they aren't linked.
         .dsym = null,
@@ -72,6 +84,14 @@ pub fn initShared(
     b: *std.Build,
     deps: *const SharedDeps,
 ) !GhosttyLib {
+    // For dynamic linking, we prefer dynamic linking and to search by
+    // mode first. Mode first will search all paths for a dynamic library
+    // before falling back to static.
+    const dynamic_link_opts: std.Build.Module.LinkSystemLibraryOptions = .{
+        .preferred_link_mode = .dynamic,
+        .search_strategy = .mode_first,
+    };
+
     const lib = b.addLibrary(.{
         .name = "ghostty",
         .linkage = .dynamic,
@@ -80,7 +100,7 @@ pub fn initShared(
             .target = deps.config.target,
             .optimize = deps.config.optimize,
             .strip = deps.config.strip,
-            .omit_frame_pointer = deps.config.strip,
+            .omit_frame_pointer = deps.config.omitFramePointer(),
             .unwind_tables = if (deps.config.strip) .none else .sync,
         }),
 
@@ -99,12 +119,12 @@ pub fn initShared(
     {
         // The CRT initialization code in msvcrt.lib calls __vcrt_initialize
         // and __acrt_initialize, which are in the static CRT libraries.
-        lib.linkSystemLibrary("libvcruntime");
+        lib.root_module.linkSystemLibrary("libvcruntime", dynamic_link_opts);
 
         // ucrt.lib is in the Windows SDK 'ucrt' dir. Detect the SDK
         // installation and add the UCRT library path.
         const arch = deps.config.target.result.cpu.arch;
-        const sdk = std.zig.WindowsSdk.find(b.allocator, arch) catch null;
+        const sdk = std.zig.WindowsSdk.find(b.allocator, b.graph.io, arch, &b.graph.environ_map) catch null;
         if (sdk) |s| {
             if (s.windows10sdk) |w10| {
                 const arch_str: []const u8 = switch (arch) {
@@ -120,11 +140,11 @@ pub fn initShared(
                 ) catch null;
 
                 if (ucrt_lib_path) |path| {
-                    lib.addLibraryPath(.{ .cwd_relative = path });
+                    lib.root_module.addLibraryPath(.{ .cwd_relative = path });
                 }
             }
         }
-        lib.linkSystemLibrary("libucrt");
+        lib.root_module.linkSystemLibrary("libucrt", dynamic_link_opts);
     }
 
     // Get our debug symbols
diff --git a/src/build/GhosttyLibVt.zig b/src/build/GhosttyLibVt.zig
index 65f945bfd..32ed2aa72 100644
--- a/src/build/GhosttyLibVt.zig
+++ b/src/build/GhosttyLibVt.zig
@@ -5,6 +5,7 @@ const builtin = @import("builtin");
 const assert = std.debug.assert;
 const RunStep = std.Build.Step.Run;
 const CombineArchivesStep = @import("CombineArchivesStep.zig");
+const LibsystemOverrideStep = @import("LibsystemOverrideStep.zig");
 const Config = @import("Config.zig");
 const GhosttyZig = @import("GhosttyZig.zig");
 const LipoStep = @import("LipoStep.zig");
@@ -174,7 +175,12 @@ pub fn initStaticAppleUniversal(
             .os_tag = p.os_tag,
             .os_version_min = Config.osVersionMin(p.os_tag),
         };
-        if (detectAppleSDK(b.resolveTargetQuery(target_query).result)) {
+        if (detectAppleSDK(
+            b.graph.io,
+            b.allocator,
+            &b.graph.environ_map,
+            b.resolveTargetQuery(target_query).result,
+        )) {
             const dev_zig = try zig.retarget(b, cfg, deps, b.resolveTargetQuery(target_query));
             result.put(p.device, try initStatic(b, &dev_zig));
 
@@ -290,22 +296,44 @@ fn initLib(
         const combined = CombineArchivesStep.create(b, target, "ghostty-vt", sources.items);
         combined.step.dependOn(&lib.step);
 
+        // On Darwin, prefer libSystem's libc/libm over the bundled
+        // compiler-rt for consumers of this archive. See GhosttyLib
+        // and libsystem_override.sh for details.
+        const override = LibsystemOverrideStep.create(
+            b,
+            target,
+            combined.output,
+            "libghostty-vt-fat.a",
+        );
+
         return .{
-            .step = combined.step,
+            .step = override.step orelse combined.step,
             .artifact = &b.addInstallArtifact(lib, .{}).step,
             .kind = kind,
-            .output = combined.output,
+            .output = override.output,
             .dsym = dsymutil,
             .pkg_config = if (pcs) |v| v.shared else null,
             .pkg_config_static = if (pcs) |v| v.static else null,
         };
     }
 
+    // Same libSystem preference for the plain (no vendored SIMD)
+    // static archive; a no-op off Darwin.
+    const override: LibsystemOverrideStep.Result = if (kind == .static) LibsystemOverrideStep.create(
+        b,
+        target,
+        lib.getEmittedBin(),
+        "libghostty-vt-static.a",
+    ) else .{
+        .step = null,
+        .output = lib.getEmittedBin(),
+    };
+
     return .{
-        .step = &lib.step,
+        .step = override.step orelse &lib.step,
         .artifact = &b.addInstallArtifact(lib, .{}).step,
         .kind = kind,
-        .output = lib.getEmittedBin(),
+        .output = override.output,
         .dsym = dsymutil,
         .pkg_config = if (pcs) |v| v.shared else null,
         .pkg_config_static = if (pcs) |v| v.static else null,
@@ -438,12 +466,21 @@ pub fn xcframework(
 }
 
 /// Returns true if the Apple SDK for the given target is installed.
-fn detectAppleSDK(target: std.Target) bool {
-    _ = std.zig.LibCInstallation.findNative(.{
-        .allocator = std.heap.page_allocator,
-        .target = &target,
-        .verbose = false,
-    }) catch return false;
+fn detectAppleSDK(
+    io: std.Io,
+    alloc: std.mem.Allocator,
+    environ_map: *const std.process.Environ.Map,
+    target: std.Target,
+) bool {
+    _ = std.zig.LibCInstallation.findNative(
+        alloc,
+        io,
+        .{
+            .environ_map = environ_map,
+            .target = &target,
+            .verbose = false,
+        },
+    ) catch return false;
     return true;
 }
 
diff --git a/src/build/GhosttyResources.zig b/src/build/GhosttyResources.zig
index 6f857655b..673c7e56a 100644
--- a/src/build/GhosttyResources.zig
+++ b/src/build/GhosttyResources.zig
@@ -21,9 +21,9 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
             .strip = false,
             .omit_frame_pointer = false,
             .unwind_tables = .sync,
+            .link_libc = true,
         }),
     });
-    build_data_exe.linkLibC();
 
     deps.help_strings.addImport(build_data_exe);
 
@@ -39,7 +39,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
         const run = b.addRunArtifact(build_data_exe);
         run.addArg("+terminfo");
         const wf = b.addWriteFiles();
-        const source = wf.addCopyFile(run.captureStdOut(), "ghostty.terminfo");
+        const source = wf.addCopyFile(run.captureStdOut(.{}), "ghostty.terminfo");
 
         if (cfg.emit_terminfo) {
             const source_install = b.addInstallFile(
@@ -63,8 +63,8 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
             const run_step = RunStep.create(b, "infotocap");
             run_step.addArg("infotocap");
             run_step.addFileArg(source);
-            const out_source = run_step.captureStdOut();
-            _ = run_step.captureStdErr(); // so we don't see stderr
+            const out_source = run_step.captureStdOut(.{});
+            _ = run_step.captureStdErr(.{}); // so we don't see stderr
 
             const cap_install = b.addInstallFile(
                 out_source,
@@ -84,7 +84,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
             const path = run_step.addOutputFileArg(terminfo_share_dir);
 
             run_step.addFileArg(source);
-            _ = run_step.captureStdErr(); // so we don't see stderr
+            _ = run_step.captureStdErr(.{}); // so we don't see stderr
 
             // Ensure that `share/terminfo` is a directory, otherwise the `cp
             // -R` will create a file named `share/terminfo`
@@ -143,7 +143,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
         const run = b.addRunArtifact(build_data_exe);
         run.addArg("+fish");
         const wf = b.addWriteFiles();
-        _ = wf.addCopyFile(run.captureStdOut(), "ghostty.fish");
+        _ = wf.addCopyFile(run.captureStdOut(.{}), "ghostty.fish");
 
         const install_step = b.addInstallDirectory(.{
             .source_dir = wf.getDirectory(),
@@ -158,7 +158,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
         const run = b.addRunArtifact(build_data_exe);
         run.addArg("+zsh");
         const wf = b.addWriteFiles();
-        _ = wf.addCopyFile(run.captureStdOut(), "_ghostty");
+        _ = wf.addCopyFile(run.captureStdOut(.{}), "_ghostty");
 
         const install_step = b.addInstallDirectory(.{
             .source_dir = wf.getDirectory(),
@@ -173,7 +173,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
         const run = b.addRunArtifact(build_data_exe);
         run.addArg("+bash");
         const wf = b.addWriteFiles();
-        _ = wf.addCopyFile(run.captureStdOut(), "ghostty.bash");
+        _ = wf.addCopyFile(run.captureStdOut(.{}), "ghostty.bash");
 
         const install_step = b.addInstallDirectory(.{
             .source_dir = wf.getDirectory(),
@@ -190,22 +190,22 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
         {
             const run = b.addRunArtifact(build_data_exe);
             run.addArg("+vim-syntax");
-            _ = wf.addCopyFile(run.captureStdOut(), "syntax/ghostty.vim");
+            _ = wf.addCopyFile(run.captureStdOut(.{}), "syntax/ghostty.vim");
         }
         {
             const run = b.addRunArtifact(build_data_exe);
             run.addArg("+vim-ftdetect");
-            _ = wf.addCopyFile(run.captureStdOut(), "ftdetect/ghostty.vim");
+            _ = wf.addCopyFile(run.captureStdOut(.{}), "ftdetect/ghostty.vim");
         }
         {
             const run = b.addRunArtifact(build_data_exe);
             run.addArg("+vim-ftplugin");
-            _ = wf.addCopyFile(run.captureStdOut(), "ftplugin/ghostty.vim");
+            _ = wf.addCopyFile(run.captureStdOut(.{}), "ftplugin/ghostty.vim");
         }
         {
             const run = b.addRunArtifact(build_data_exe);
             run.addArg("+vim-compiler");
-            _ = wf.addCopyFile(run.captureStdOut(), "compiler/ghostty.vim");
+            _ = wf.addCopyFile(run.captureStdOut(.{}), "compiler/ghostty.vim");
         }
 
         const vim_step = b.addInstallDirectory(.{
@@ -233,7 +233,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
         const run = b.addRunArtifact(build_data_exe);
         run.addArg("+sublime");
         const wf = b.addWriteFiles();
-        _ = wf.addCopyFile(run.captureStdOut(), "ghostty.sublime-syntax");
+        _ = wf.addCopyFile(run.captureStdOut(.{}), "ghostty.sublime-syntax");
 
         const install_step = b.addInstallDirectory(.{
             .source_dir = wf.getDirectory(),
@@ -358,10 +358,10 @@ fn addLinuxAppResources(
         // Template output has a single header line we want to remove.
         // We use `tail` to do it since its part of the POSIX standard.
         const tail = b.addSystemCommand(&.{ "tail", "-n", "+2" });
-        tail.setStdIn(.{ .lazy_path = tpl.getOutput() });
+        tail.setStdIn(.{ .lazy_path = tpl.getOutputFile() });
 
         const copy = b.addInstallFile(
-            tail.captureStdOut(),
+            tail.captureStdOut(.{}),
             template[1],
         );
 
diff --git a/src/build/GhosttyWebdata.zig b/src/build/GhosttyWebdata.zig
index e29b20c25..7057ad034 100644
--- a/src/build/GhosttyWebdata.zig
+++ b/src/build/GhosttyWebdata.zig
@@ -40,7 +40,7 @@ pub fn init(
         }
 
         const webgen_config_step = b.addRunArtifact(webgen_config);
-        const webgen_config_out = webgen_config_step.captureStdOut();
+        const webgen_config_out = webgen_config_step.captureStdOut(.{});
 
         try steps.append(b.allocator, &b.addInstallFile(
             webgen_config_out,
@@ -71,7 +71,7 @@ pub fn init(
         }
 
         const webgen_actions_step = b.addRunArtifact(webgen_actions);
-        const webgen_actions_out = webgen_actions_step.captureStdOut();
+        const webgen_actions_out = webgen_actions_step.captureStdOut(.{});
 
         try steps.append(b.allocator, &b.addInstallFile(
             webgen_actions_out,
@@ -102,7 +102,7 @@ pub fn init(
         }
 
         const webgen_commands_step = b.addRunArtifact(webgen_commands);
-        const webgen_commands_out = webgen_commands_step.captureStdOut();
+        const webgen_commands_out = webgen_commands_step.captureStdOut(.{});
 
         try steps.append(b.allocator, &b.addInstallFile(
             webgen_commands_out,
diff --git a/src/build/GhosttyXcodebuild.zig b/src/build/GhosttyXcodebuild.zig
index 81af994ca..6f7e18dc3 100644
--- a/src/build/GhosttyXcodebuild.zig
+++ b/src/build/GhosttyXcodebuild.zig
@@ -48,21 +48,21 @@ pub fn init(
         },
     };
 
-    const env = try std.process.getEnvMap(b.allocator);
+    const env = b.graph.environ_map;
     const app_path = b.fmt("macos/build/{s}/Ghostty.app", .{xc_config});
 
     // Our step to build the Ghostty macOS app.
     const build = build: {
         // External environment variables can mess up xcodebuild, so
         // we create a new empty environment.
-        const env_map = try b.allocator.create(std.process.EnvMap);
+        const env_map = try b.allocator.create(std.process.Environ.Map);
         env_map.* = .init(b.allocator);
         if (env.get("PATH")) |v| try env_map.put("PATH", v);
 
         const step = RunStep.create(b, "xcodebuild");
         step.has_side_effects = true;
         step.cwd = b.path("macos");
-        step.env_map = env_map;
+        step.environ_map = env_map;
         step.addArgs(&.{
             "xcodebuild",
             "-target",
@@ -91,14 +91,14 @@ pub fn init(
     };
 
     const xctest = xctest: {
-        const env_map = try b.allocator.create(std.process.EnvMap);
+        const env_map = try b.allocator.create(std.process.Environ.Map);
         env_map.* = .init(b.allocator);
         if (env.get("PATH")) |v| try env_map.put("PATH", v);
 
         const step = RunStep.create(b, "xcodebuild test");
         step.has_side_effects = true;
         step.cwd = b.path("macos");
-        step.env_map = env_map;
+        step.environ_map = env_map;
         step.addArgs(&.{
             "xcodebuild",
             "test",
diff --git a/src/build/GhosttyZig.zig b/src/build/GhosttyZig.zig
index 44c300e15..4671219e0 100644
--- a/src/build/GhosttyZig.zig
+++ b/src/build/GhosttyZig.zig
@@ -64,7 +64,7 @@ fn initInner(
     vt_c_name: []const u8,
 ) !GhosttyZig {
     // Terminal module build options
-    var vt_options = cfg.terminalOptions(.lib);
+    var vt_options = cfg.terminalOptions(.lib, cfg.optimize);
     vt_options.artifact = .lib;
     // We presently don't allow Oniguruma in our Zig module at all.
     // We should expose this as a build option in the future so we can
@@ -135,7 +135,7 @@ fn initVt(
     deps.unicode_tables.addModuleImport(vt);
 
     // We need uucode for grapheme break support
-    deps.addUucode(b, vt, cfg.target, cfg.optimize);
+    vt.addImport("uucode", deps.uucode_mod);
 
     // If SIMD is enabled, add all our SIMD dependencies.
     if (cfg.simd) {
diff --git a/src/build/GitVersion.zig b/src/build/GitVersion.zig
index 41cc7f84f..2365a110c 100644
--- a/src/build/GitVersion.zig
+++ b/src/build/GitVersion.zig
@@ -23,7 +23,7 @@ pub fn detect(b: *std.Build) !Version {
         const tmp: []u8 = b.runAllowFail(
             &[_][]const u8{ "git", "-C", b.build_root.path orelse ".", "rev-parse", "--abbrev-ref", "HEAD" },
             &code,
-            .Ignore,
+            .ignore,
         ) catch |err| switch (err) {
             error.FileNotFound => return error.GitNotFound,
             error.ExitCodeFailure => return error.GitNotRepository,
@@ -44,19 +44,19 @@ pub fn detect(b: *std.Build) !Version {
         const output = b.runAllowFail(
             &[_][]const u8{ "git", "-C", b.build_root.path orelse ".", "-c", "log.showSignature=false", "log", "--pretty=format:%h", "-n", "1" },
             &code,
-            .Ignore,
+            .ignore,
         ) catch |err| switch (err) {
             error.FileNotFound => return error.GitNotFound,
             else => return err,
         };
 
-        break :short_hash std.mem.trimRight(u8, output, "\r\n ");
+        break :short_hash std.mem.trimEnd(u8, output, "\r\n ");
     };
 
     const tag = b.runAllowFail(
         &[_][]const u8{ "git", "-C", b.build_root.path orelse ".", "describe", "--exact-match", "--tags" },
         &code,
-        .Ignore,
+        .ignore,
     ) catch |err| switch (err) {
         error.FileNotFound => return error.GitNotFound,
         error.ExitCodeFailure => "", // expected
@@ -70,7 +70,7 @@ pub fn detect(b: *std.Build) !Version {
         "diff",
         "--quiet",
         "--exit-code",
-    }, &code, .Ignore) catch |err| switch (err) {
+    }, &code, .ignore) catch |err| switch (err) {
         error.FileNotFound => return error.GitNotFound,
         error.ExitCodeFailure => {}, // expected
         else => return err,
@@ -80,7 +80,7 @@ pub fn detect(b: *std.Build) !Version {
     return .{
         .short_hash = short_hash,
         .changes = changes,
-        .tag = if (tag.len > 0) std.mem.trimRight(u8, tag, "\r\n ") else null,
-        .branch = std.mem.trimRight(u8, branch, "\r\n "),
+        .tag = if (tag.len > 0) std.mem.trimEnd(u8, tag, "\r\n ") else null,
+        .branch = std.mem.trimEnd(u8, branch, "\r\n "),
     };
 }
diff --git a/src/build/HelpStrings.zig b/src/build/HelpStrings.zig
index 96505caba..24ae82e2a 100644
--- a/src/build/HelpStrings.zig
+++ b/src/build/HelpStrings.zig
@@ -34,7 +34,7 @@ pub fn init(b: *std.Build, cfg: *const Config) !HelpStrings {
 
     // Generated Zig files have to end with .zig
     const wf = b.addWriteFiles();
-    const output = wf.addCopyFile(help_run.captureStdOut(), "helpgen.zig");
+    const output = wf.addCopyFile(help_run.captureStdOut(.{}), "helpgen.zig");
 
     return .{
         .exe = exe,
diff --git a/src/build/LibsystemOverrideStep.zig b/src/build/LibsystemOverrideStep.zig
new file mode 100644
index 000000000..3e1cafa5e
--- /dev/null
+++ b/src/build/LibsystemOverrideStep.zig
@@ -0,0 +1,51 @@
+//! Wraps a Darwin static archive with the libsystem_override.sh
+//! post-processing step so that consumers linking the archive bind
+//! well-known libc/libm symbols (memcpy, memmove, memset, cos, sin,
+//! ...) to Apple's libSystem instead of the bundled Zig compiler-rt.
+//! See src/build/libsystem_override.sh for the full rationale.
+//!
+//! This applies to every static archive we produce, public
+//! (e.g. libghostty-vt) and app-internal alike: the compiler-rt
+//! bundle must stay because the few symbols libSystem does not
+//! provide (f128 conversions, *q math, sincos*, ___zig_probe_stack)
+//! have live references, e.g. from the bundled ubsan runtime and
+//! x86_64 stack probing in Debug builds.
+//!
+//! Note shared libraries can't use either approach: Zig 0.16 links
+//! compiler-rt as an eagerly-included object, so its definitions are
+//! already bound into the dylib at link time and cannot be repaired
+//! post-hoc. That needs an upstream Zig fix.
+const std = @import("std");
+const builtin = @import("builtin");
+
+pub const Result = struct {
+    /// The step performing the override, or null if the override
+    /// doesn't apply to this target/host (in which case `output` is
+    /// the unmodified input).
+    step: ?*std.Build.Step,
+    output: std.Build.LazyPath,
+};
+
+/// Post-process the given static archive on Darwin. Requires a Darwin
+/// host for the Apple toolchain (nmedit); in all other configurations
+/// this is a no-op and the input is returned unmodified, which is
+/// functional (the bundled compiler-rt symbols are used), just slower.
+pub fn create(
+    b: *std.Build,
+    target: std.Build.ResolvedTarget,
+    input: std.Build.LazyPath,
+    out_name: []const u8,
+) Result {
+    if (!target.result.os.tag.isDarwin() or
+        comptime !builtin.os.tag.isDarwin())
+    {
+        return .{ .step = null, .output = input };
+    }
+
+    const run = b.addSystemCommand(&.{"/bin/sh"});
+    run.setName("libsystem override");
+    run.addFileArg(b.path("src/build/libsystem_override.sh"));
+    run.addFileArg(input);
+    const output = run.addOutputFileArg(out_name);
+    return .{ .step = &run.step, .output = output };
+}
diff --git a/src/build/SharedDeps.zig b/src/build/SharedDeps.zig
index b68be92d0..4877686c4 100644
--- a/src/build/SharedDeps.zig
+++ b/src/build/SharedDeps.zig
@@ -9,6 +9,7 @@ const MetallibStep = @import("MetallibStep.zig");
 const UnicodeTables = @import("UnicodeTables.zig");
 const GhosttyFrameData = @import("GhosttyFrameData.zig");
 const DistResource = @import("GhosttyDist.zig").Resource;
+const gtk_helpers = @import("gtk.zig");
 
 config: *const Config,
 
@@ -19,6 +20,43 @@ unicode_tables: UnicodeTables,
 framedata: GhosttyFrameData,
 uucode_tables: std.Build.LazyPath,
 
+/// Singleton uucode module, instantiated once in `init` and reused
+/// everywhere so that ghostty and vaxis share the same compiled tables in
+/// each final binary instead of each linking its own copy.
+///
+/// Sharing one instance is also a hard requirement (not just an
+/// optimization) for Zig 0.16's strict module model. `SharedDeps.add` runs
+/// many times across different (target, optimize) tuples (macos-aarch64,
+/// macos-x86_64, ios-aarch64, Debug + ReleaseFast, etc.), and on each
+/// call we have to wire uucode into both the step's root module and into
+/// vaxis_mod (because vaxis's `Parser.zig` does `@import("uucode")` and
+/// we pass `external_uucode = true` to vaxis's build.zig so vaxis doesn't
+/// instantiate its own uucode dep). If those two import bindings ever
+/// resolve to *different* `*Module` pointers within a single Compile
+/// step's analysis, Zig fails with:
+///
+///     vaxis/src/Parser.zig: file exists in modules 'uucode' and 'uucode0'
+///
+/// because all those uucode module instances share the same physical
+/// `uucode/src/root.zig` file on disk, and Zig requires every file to belong
+/// to exactly one module within a Compile graph.
+///
+/// The natural way to keep them the same would be to call
+/// `b.lazyDependency("uucode", .{ .tables_path, .build_config_path })`
+/// from each call site and let Zig's dependency cache deduplicate
+/// identical args. That fails because of a bug in Zig's
+/// `userLazyPathsAreTheSame` (Build.zig) where the `.src_path` and
+/// `.generated` equality checks are inverted: `if (std.mem.eql(...))
+/// return false` instead of `if (!std.mem.eql(...)) return false`. The
+/// dep cache key therefore always misses whenever any arg is a
+/// `b.path(...)` LazyPath, so each call returns a fresh `*Dependency`
+/// with a fresh `*Module`. Hoisting the dep into one eager
+/// `b.dependency` call here sidesteps the cache entirely.
+///
+/// This conflict is independent of whether vaxis itself is acquired as a
+/// singleton or per-target dep.
+uucode_mod: *std.Build.Module,
+
 /// Used to keep track of a list of file sources.
 pub const LazyPathList = std.ArrayList(std.Build.LazyPath);
 
@@ -31,12 +69,20 @@ pub fn init(b: *std.Build, cfg: *const Config) !SharedDeps {
         break :blk uucode.namedLazyPath("tables.zig");
     };
 
+    // Instantiate the singleton uucode module that both ghostty and vaxis
+    // import. See the doc comment on `uucode_mod`.
+    const uucode_mod = b.dependency("uucode", .{
+        .tables_path = uucode_tables,
+        .build_config_path = b.path("src/build/uucode_config.zig"),
+    }).module("uucode");
+
     var result: SharedDeps = .{
         .config = cfg,
         .help_strings = try .init(b, cfg),
         .unicode_tables = try .init(b, uucode_tables),
         .framedata = try .init(b),
         .uucode_tables = uucode_tables,
+        .uucode_mod = uucode_mod,
 
         // Setup by retarget
         .options = undefined,
@@ -133,7 +179,10 @@ pub fn add(
     step.root_module.addOptions("build_options", self.options);
 
     // Every exe needs the terminal options
-    self.config.terminalOptions(.ghostty).add(b, step.root_module);
+    self.config.terminalOptions(.ghostty, optimize).add(b, step.root_module);
+
+    // Every exe needs the uucode module
+    step.root_module.addImport("uucode", self.uucode_mod);
 
     // C imports for locale constants and functions
     {
@@ -143,11 +192,15 @@ pub fn add(
             .optimize = optimize,
         });
         if (target.result.os.tag.isDarwin()) {
-            const libc = try std.zig.LibCInstallation.findNative(.{
-                .allocator = b.allocator,
-                .target = &target.result,
-                .verbose = false,
-            });
+            const libc = try std.zig.LibCInstallation.findNative(
+                b.allocator,
+                b.graph.io,
+                .{
+                    .environ_map = &b.graph.environ_map,
+                    .target = &target.result,
+                    .verbose = false,
+                },
+            );
             c.addSystemIncludePath(.{ .cwd_relative = libc.sys_include_dir.? });
         }
         step.root_module.addImport("locale-c", c.createModule());
@@ -166,11 +219,15 @@ pub fn add(
             });
             switch (target.result.os.tag) {
                 .macos => {
-                    const libc = try std.zig.LibCInstallation.findNative(.{
-                        .allocator = b.allocator,
-                        .target = &target.result,
-                        .verbose = false,
-                    });
+                    const libc = try std.zig.LibCInstallation.findNative(
+                        b.allocator,
+                        b.graph.io,
+                        .{
+                            .environ_map = &b.graph.environ_map,
+                            .target = &target.result,
+                            .verbose = false,
+                        },
+                    );
                     c.addSystemIncludePath(.{ .cwd_relative = libc.sys_include_dir.? });
                 },
                 else => {},
@@ -194,10 +251,10 @@ pub fn add(
         );
 
         if (b.systemIntegrationOption("freetype", .{})) {
-            step.linkSystemLibrary2("bzip2", dynamic_link_opts);
-            step.linkSystemLibrary2("freetype2", dynamic_link_opts);
+            step.root_module.linkSystemLibrary("bzip2", dynamic_link_opts);
+            step.root_module.linkSystemLibrary("freetype2", dynamic_link_opts);
         } else {
-            step.linkLibrary(freetype_dep.artifact("freetype"));
+            step.root_module.linkLibrary(freetype_dep.artifact("freetype"));
             try static_libs.append(
                 b.allocator,
                 freetype_dep.artifact("freetype").getEmittedBin(),
@@ -219,9 +276,9 @@ pub fn add(
                 harfbuzz_dep.module("harfbuzz"),
             );
             if (b.systemIntegrationOption("harfbuzz", .{})) {
-                step.linkSystemLibrary2("harfbuzz", dynamic_link_opts);
+                step.root_module.linkSystemLibrary("harfbuzz", dynamic_link_opts);
             } else {
-                step.linkLibrary(harfbuzz_dep.artifact("harfbuzz"));
+                step.root_module.linkLibrary(harfbuzz_dep.artifact("harfbuzz"));
                 try static_libs.append(
                     b.allocator,
                     harfbuzz_dep.artifact("harfbuzz").getEmittedBin(),
@@ -243,9 +300,9 @@ pub fn add(
             );
 
             if (b.systemIntegrationOption("fontconfig", .{})) {
-                step.linkSystemLibrary2("fontconfig", dynamic_link_opts);
+                step.root_module.linkSystemLibrary("fontconfig", dynamic_link_opts);
             } else {
-                step.linkLibrary(fontconfig_dep.artifact("fontconfig"));
+                step.root_module.linkLibrary(fontconfig_dep.artifact("fontconfig"));
                 try static_libs.append(
                     b.allocator,
                     fontconfig_dep.artifact("fontconfig").getEmittedBin(),
@@ -263,7 +320,7 @@ pub fn add(
             .target = target,
             .optimize = optimize,
         })) |libpng_dep| {
-            step.linkLibrary(libpng_dep.artifact("png"));
+            step.root_module.linkLibrary(libpng_dep.artifact("png"));
             try static_libs.append(
                 b.allocator,
                 libpng_dep.artifact("png").getEmittedBin(),
@@ -277,7 +334,7 @@ pub fn add(
             .target = target,
             .optimize = optimize,
         })) |zlib_dep| {
-            step.linkLibrary(zlib_dep.artifact("z"));
+            step.root_module.linkLibrary(zlib_dep.artifact("z"));
             try static_libs.append(
                 b.allocator,
                 zlib_dep.artifact("z").getEmittedBin(),
@@ -295,9 +352,9 @@ pub fn add(
             oniguruma_dep.module("oniguruma"),
         );
         if (b.systemIntegrationOption("oniguruma", .{})) {
-            step.linkSystemLibrary2("oniguruma", dynamic_link_opts);
+            step.root_module.linkSystemLibrary("oniguruma", dynamic_link_opts);
         } else {
-            step.linkLibrary(oniguruma_dep.artifact("oniguruma"));
+            step.root_module.linkLibrary(oniguruma_dep.artifact("oniguruma"));
             try static_libs.append(
                 b.allocator,
                 oniguruma_dep.artifact("oniguruma").getEmittedBin(),
@@ -312,13 +369,13 @@ pub fn add(
     })) |glslang_dep| {
         step.root_module.addImport("glslang", glslang_dep.module("glslang"));
         if (b.systemIntegrationOption("glslang", .{})) {
-            step.linkSystemLibrary2("glslang", dynamic_link_opts);
-            step.linkSystemLibrary2(
+            step.root_module.linkSystemLibrary("glslang", dynamic_link_opts);
+            step.root_module.linkSystemLibrary(
                 "glslang-default-resource-limits",
                 dynamic_link_opts,
             );
         } else {
-            step.linkLibrary(glslang_dep.artifact("glslang"));
+            step.root_module.linkLibrary(glslang_dep.artifact("glslang"));
             try static_libs.append(
                 b.allocator,
                 glslang_dep.artifact("glslang").getEmittedBin(),
@@ -336,9 +393,9 @@ pub fn add(
             spirv_cross_dep.module("spirv_cross"),
         );
         if (b.systemIntegrationOption("spirv-cross", .{})) {
-            step.linkSystemLibrary2("spirv-cross-c-shared", dynamic_link_opts);
+            step.root_module.linkSystemLibrary("spirv-cross-c-shared", dynamic_link_opts);
         } else {
-            step.linkLibrary(spirv_cross_dep.artifact("spirv_cross"));
+            step.root_module.linkLibrary(spirv_cross_dep.artifact("spirv_cross"));
             try static_libs.append(
                 b.allocator,
                 spirv_cross_dep.artifact("spirv_cross").getEmittedBin(),
@@ -357,7 +414,7 @@ pub fn add(
                 "sentry",
                 sentry_dep.module("sentry"),
             );
-            step.linkLibrary(sentry_dep.artifact("sentry"));
+            step.root_module.linkLibrary(sentry_dep.artifact("sentry"));
             try static_libs.append(
                 b.allocator,
                 sentry_dep.artifact("sentry").getEmittedBin(),
@@ -404,18 +461,18 @@ pub fn add(
     if (step.rootModuleTarget().os.tag == .linux) {
         const triple = try step.rootModuleTarget().linuxTriple(b.allocator);
         const path = b.fmt("/usr/lib/{s}", .{triple});
-        if (std.fs.accessAbsolute(path, .{})) {
-            step.addLibraryPath(.{ .cwd_relative = path });
+        if (std.Io.Dir.accessAbsolute(b.graph.io, path, .{})) {
+            step.root_module.addLibraryPath(.{ .cwd_relative = path });
         } else |_| {}
     }
 
     // C files
-    step.linkLibC();
-    step.addIncludePath(b.path("src/stb"));
+    step.root_module.link_libc = true;
+    step.root_module.addIncludePath(b.path("src/stb"));
     // Disable ubsan for MSVC: Zig's ubsan runtime cannot be bundled
     // on Windows (LNK4229), leaving __ubsan_handle_* unresolved when
     // the static archive is consumed by an external linker.
-    step.addCSourceFiles(.{
+    step.root_module.addCSourceFiles(.{
         .files = &.{"src/stb/stb.c"},
         .flags = if (step.rootModuleTarget().abi == .msvc)
             &.{ "-fno-sanitize=undefined", "-fno-sanitize-trap=undefined" }
@@ -423,7 +480,7 @@ pub fn add(
             &.{},
     });
     if (step.rootModuleTarget().os.tag == .linux) {
-        step.addIncludePath(b.path("src/apprt/gtk"));
+        step.root_module.addIncludePath(b.path("src/apprt/gtk"));
     }
 
     // libcpp is required for various dependencies. On MSVC, we must
@@ -433,7 +490,7 @@ pub fn add(
     // include directories (already added via linkLibC above) contain
     // both C and C++ headers, so linkLibCpp is not needed.
     if (step.rootModuleTarget().abi != .msvc) {
-        step.linkLibCpp();
+        step.root_module.link_libcpp = true;
     }
 
     // We always require the system SDK so that our system headers are available.
@@ -452,8 +509,14 @@ pub fn add(
     if (b.lazyDependency("opengl", .{})) |dep| {
         step.root_module.addImport("opengl", dep.module("opengl"));
     }
-    if (b.lazyDependency("vaxis", .{})) |dep| {
-        step.root_module.addImport("vaxis", dep.module("vaxis"));
+    if (b.lazyDependency("vaxis", .{
+        .target = target,
+        .optimize = optimize,
+        .external_uucode = true,
+    })) |dep| {
+        const vaxis = dep.module("vaxis");
+        step.root_module.addImport("vaxis", vaxis);
+        vaxis.addImport("uucode", self.uucode_mod);
     }
     if (b.lazyDependency("wuffs", .{
         .target = target,
@@ -473,7 +536,6 @@ pub fn add(
     })) |dep| {
         step.root_module.addImport("z2d", dep.module("z2d"));
     }
-    self.addUucode(b, step.root_module, target, optimize);
     if (b.lazyDependency("zf", .{
         .target = target,
         .optimize = optimize,
@@ -502,7 +564,7 @@ pub fn add(
                 "macos",
                 macos_dep.module("macos"),
             );
-            step.linkLibrary(
+            step.root_module.linkLibrary(
                 macos_dep.artifact("macos"),
             );
             try static_libs.append(
@@ -512,7 +574,7 @@ pub fn add(
         }
 
         if (self.config.renderer == .opengl) {
-            step.linkFramework("OpenGL");
+            step.root_module.linkFramework("OpenGL", .{});
         }
 
         // Apple platforms do not include libc libintl so we bundle it.
@@ -523,7 +585,7 @@ pub fn add(
             .target = target,
             .optimize = optimize,
         })) |libintl_dep| {
-            step.linkLibrary(libintl_dep.artifact("intl"));
+            step.root_module.linkLibrary(libintl_dep.artifact("intl"));
             try static_libs.append(
                 b.allocator,
                 libintl_dep.artifact("intl").getEmittedBin(),
@@ -543,7 +605,7 @@ pub fn add(
         .@"backend-opengl3" = !target.result.os.tag.isDarwin(),
     })) |dep| {
         step.root_module.addImport("dcimgui", dep.module("dcimgui"));
-        step.linkLibrary(dep.artifact("dcimgui"));
+        step.root_module.linkLibrary(dep.artifact("dcimgui"));
         try static_libs.append(
             b.allocator,
             dep.artifact("dcimgui").getEmittedBin(),
@@ -592,15 +654,38 @@ pub fn add(
     // If we're building an exe then we have additional dependencies.
     if (step.kind != .lib) {
         // We always statically compile glad
-        step.addIncludePath(b.path("vendor/glad/include/"));
-        step.addCSourceFile(.{
+        step.root_module.addIncludePath(b.path("vendor/glad/include/"));
+        step.root_module.addCSourceFile(.{
             .file = b.path("vendor/glad/src/gl.c"),
             .flags = &.{},
         });
 
         // When we're targeting flatpak we ALWAYS link GTK so we
         // get access to glib for dbus.
-        if (self.config.flatpak) step.linkSystemLibrary2("gtk4", dynamic_link_opts);
+        if (self.config.flatpak) {
+            step.root_module.linkSystemLibrary("gtk4", dynamic_link_opts);
+
+            // We need to translate gio headers too
+            gio_translate: {
+                // translate-c stuff
+                const translate_c = b.lazyImport(@import("../../build.zig"), "translate_c") orelse
+                    break :gio_translate;
+                const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse
+                    break :gio_translate;
+                const translated: translate_c.Translator = .init(translate_c_dep, .{
+                    .c_source_file = b.addWriteFiles().add("gio_c.h",
+                        \\#include <gio/gio.h>
+                        \\#include <gio/gunixfdlist.h>
+                    ),
+                    .target = target,
+                    .optimize = optimize,
+                    .link_system_libs = &.{
+                        .{ .name = "gio-2.0", .options = dynamic_link_opts },
+                    },
+                });
+                step.root_module.addImport("gio_c", translated.mod);
+            }
+        }
 
         switch (self.config.app_runtime) {
             .none => {},
@@ -643,12 +728,44 @@ fn addGtkNg(
             step.root_module.addImport(name, gobject.module(module));
         }
     }
+    gtk_adw_translate: {
+        // translate-c stuff
+        const translate_c = b.lazyImport(@import("../../build.zig"), "translate_c") orelse break :gtk_adw_translate;
+        const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse break :gtk_adw_translate;
+        const Translator = translate_c.Translator;
 
-    step.linkSystemLibrary2("gtk4", dynamic_link_opts);
-    step.linkSystemLibrary2("libadwaita-1", dynamic_link_opts);
+        {
+            // GTK headers
+            const translated: Translator = .init(translate_c_dep, .{
+                .c_source_file = b.addWriteFiles().add("gtk_c.h",
+                    \\#include <gtk/gtk.h>
+                ),
+                .target = target,
+                .optimize = optimize,
+                .link_system_libs = &.{
+                    .{ .name = "gtk4", .options = dynamic_link_opts },
+                },
+            });
+            step.root_module.addImport("gtk_c", translated.mod);
+        }
+        {
+            // Adwaita headers
+            const translated: Translator = .init(translate_c_dep, .{
+                .c_source_file = b.addWriteFiles().add("adw_c.h",
+                    \\#include <adwaita.h>
+                ),
+                .target = target,
+                .optimize = optimize,
+                .link_system_libs = &.{
+                    .{ .name = "libadwaita-1", .options = dynamic_link_opts },
+                },
+            });
+            step.root_module.addImport("adw_c", translated.mod);
+        }
+    }
 
     if (self.config.x11) {
-        step.linkSystemLibrary2("X11", dynamic_link_opts);
+        step.root_module.linkSystemLibrary("X11", dynamic_link_opts);
         if (gobject_) |gobject| {
             step.root_module.addImport(
                 "gdk_x11",
@@ -732,24 +849,39 @@ fn addGtkNg(
             // IMPORTANT: gtk4-layer-shell must be linked BEFORE
             // wayland-client, as it relies on shimming libwayland's APIs.
             if (b.systemIntegrationOption("gtk4-layer-shell", .{})) {
-                step.linkSystemLibrary2("gtk4-layer-shell-0", dynamic_link_opts);
+                step.root_module.linkSystemLibrary("gtk4-layer-shell-0", dynamic_link_opts);
             } else {
                 // gtk4-layer-shell *must* be dynamically linked,
                 // so we don't add it as a static library
                 const shared_lib = gtk4_layer_shell.artifact("gtk4-layer-shell");
                 b.installArtifact(shared_lib);
-                step.linkLibrary(shared_lib);
+                step.root_module.linkLibrary(shared_lib);
             }
         }
 
-        step.linkSystemLibrary2("wayland-client", dynamic_link_opts);
+        step.root_module.linkSystemLibrary("wayland-client", dynamic_link_opts);
     }
 
-    {
+    ghostty_resources_translate: {
         // Get our gresource c/h files and add them to our build.
         const dist = gtkNgDistResources(b);
-        step.addCSourceFile(.{ .file = dist.resources_c.path(b), .flags = &.{} });
-        step.addIncludePath(dist.resources_h.path(b).dirname());
+        const translate_c = b.lazyImport(@import("../../build.zig"), "translate_c") orelse
+            break :ghostty_resources_translate;
+        const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse
+            break :ghostty_resources_translate;
+        const translated: translate_c.Translator = .init(translate_c_dep, .{
+            .c_source_file = b.addWriteFiles().add("c.h",
+                \\#include <ghostty_resources.h>
+            ),
+            .target = target,
+            .optimize = optimize,
+            .link_system_libs = &.{
+                .{ .name = "glib-2.0", .options = dynamic_link_opts },
+            },
+        });
+        translated.addIncludePath(dist.resources_h.path(b).dirname());
+        translated.mod.addCSourceFile(.{ .file = dist.resources_c.path(b), .flags = &.{} });
+        step.root_module.addImport("ghostty_gtk_resources", translated.mod);
     }
 }
 
@@ -890,11 +1022,25 @@ pub fn gtkNgDistResources(
             .root_module = b.createModule(.{
                 .root_source_file = b.path("src/apprt/gtk/build/blueprint.zig"),
                 .target = b.graph.host,
+                .link_libc = true,
             }),
         });
-        blueprint_exe.linkLibC();
-        blueprint_exe.linkSystemLibrary2("gtk4", dynamic_link_opts);
-        blueprint_exe.linkSystemLibrary2("libadwaita-1", dynamic_link_opts);
+        adw_translate: {
+            // Adwaita headers
+            const translate_c = b.lazyImport(@import("../../build.zig"), "translate_c") orelse break :adw_translate;
+            const translate_c_dep = b.lazyDependency("translate_c", .{}) orelse break :adw_translate;
+            const translated: translate_c.Translator = .init(translate_c_dep, .{
+                .c_source_file = b.addWriteFiles().add("adw_c.h",
+                    \\#include <adwaita.h>
+                ),
+                .target = b.graph.host,
+                .optimize = .Debug,
+                .link_system_libs = &.{
+                    .{ .name = "libadwaita-1", .options = dynamic_link_opts },
+                },
+            });
+            blueprint_exe.root_module.addImport("adw_c", translated.mod);
+        }
 
         for (gresource.blueprints) |bp| {
             const blueprint_run = b.addRunArtifact(blueprint_exe);
@@ -923,7 +1069,7 @@ pub fn gtkNgDistResources(
             xml_run.addFileArg(ui_file);
         }
 
-        break :gresource_xml xml_run.captureStdOut();
+        break :gresource_xml xml_run.captureStdOut(.{});
     };
 
     const generate_c = b.addSystemCommand(&.{
@@ -964,23 +1110,6 @@ pub fn gtkNgDistResources(
     };
 }
 
-pub fn addUucode(
-    self: *const SharedDeps,
-    b: *std.Build,
-    module: *std.Build.Module,
-    target: std.Build.ResolvedTarget,
-    optimize: std.builtin.OptimizeMode,
-) void {
-    if (b.lazyDependency("uucode", .{
-        .target = target,
-        .optimize = optimize,
-        .tables_path = self.uucode_tables,
-        .build_config_path = b.path("src/build/uucode_config.zig"),
-    })) |dep| {
-        module.addImport("uucode", dep.module("uucode"));
-    }
-}
-
 // For dynamic linking, we prefer dynamic linking and to search by
 // mode first. Mode first will search all paths for a dynamic library
 // before falling back to static.
diff --git a/src/build/UnicodeTables.zig b/src/build/UnicodeTables.zig
index 17a839eaf..843ada51f 100644
--- a/src/build/UnicodeTables.zig
+++ b/src/build/UnicodeTables.zig
@@ -54,8 +54,8 @@ pub fn init(b: *std.Build, uucode_tables: std.Build.LazyPath) !UnicodeTables {
 
     // Generated Zig files have to end with .zig
     const wf = b.addWriteFiles();
-    const props_output = wf.addCopyFile(props_run.captureStdOut(), "props.zig");
-    const symbols_output = wf.addCopyFile(symbols_run.captureStdOut(), "symbols.zig");
+    const props_output = wf.addCopyFile(props_run.captureStdOut(.{}), "props.zig");
+    const symbols_output = wf.addCopyFile(symbols_run.captureStdOut(.{}), "symbols.zig");
 
     return .{
         .props_exe = props_exe,
diff --git a/src/build/XCFrameworkStep.zig b/src/build/XCFrameworkStep.zig
index 39f0f9bac..5f1b676fb 100644
--- a/src/build/XCFrameworkStep.zig
+++ b/src/build/XCFrameworkStep.zig
@@ -63,8 +63,8 @@ pub fn create(b: *std.Build, opts: Options) *XCFrameworkStep {
         run.addArg("-output");
         run.addArg(opts.out_path);
         run.expectExitCode(0);
-        _ = run.captureStdOut();
-        _ = run.captureStdErr();
+        _ = run.captureStdOut(.{});
+        _ = run.captureStdErr(.{});
         break :run run;
     };
     run_create.step.dependOn(&run_delete.step);
diff --git a/src/build/combine_archives.zig b/src/build/combine_archives.zig
index 04ec8e978..3df5ed0e4 100644
--- a/src/build/combine_archives.zig
+++ b/src/build/combine_archives.zig
@@ -11,11 +11,10 @@
 
 const std = @import("std");
 
-pub fn main() !void {
-    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
-    const alloc = gpa.allocator();
+pub fn main(init: std.process.Init) !void {
+    const alloc = init.arena.allocator();
 
-    const args = try std.process.argsAlloc(alloc);
+    const args = try init.minimal.args.toSlice(alloc);
     if (args.len < 4) {
         std.log.err("usage: combine_archives <zig_exe> <output> <input...>", .{});
         std.process.exit(1);
@@ -37,19 +36,20 @@ pub fn main() !void {
     }
     try script.appendSlice(alloc, "SAVE\nEND\n");
 
-    var child: std.process.Child = .init(&.{ zig_exe, "ar", "-M" }, alloc);
-    child.stdin_behavior = .Pipe;
-    child.stdout_behavior = .Inherit;
-    child.stderr_behavior = .Inherit;
+    var child = try std.process.spawn(init.io, .{
+        .argv = &.{ zig_exe, "ar", "-M" },
+        .stdin = .pipe,
+        .stdout = .inherit,
+        .stderr = .inherit,
+    });
 
-    try child.spawn();
-    try child.stdin.?.writeAll(script.items);
-    child.stdin.?.close();
+    try child.stdin.?.writeStreamingAll(init.io, script.items);
+    child.stdin.?.close(init.io);
     child.stdin = null;
 
-    const term = try child.wait();
-    if (term.Exited != 0) {
-        std.log.err("zig ar -M exited with code {d}", .{term.Exited});
+    const term = try child.wait(init.io);
+    if (term.exited != 0) {
+        std.log.err("zig ar -M exited with code {d}", .{term.exited});
         std.process.exit(1);
     }
 }
diff --git a/src/build/gtk.zig b/src/build/gtk.zig
index 7adb3cdb7..1035367e1 100644
--- a/src/build/gtk.zig
+++ b/src/build/gtk.zig
@@ -14,7 +14,7 @@ pub fn targets(b: *std.Build) Targets {
     const output = b.runAllowFail(
         &.{ "pkg-config", "--variable=targets", "gtk4" },
         &code,
-        .Ignore,
+        .ignore,
     ) catch return .{};
 
     const x11 = std.mem.indexOf(u8, output, "x11") != null;
diff --git a/src/build/libsystem_override.sh b/src/build/libsystem_override.sh
new file mode 100755
index 000000000..14ed191b8
--- /dev/null
+++ b/src/build/libsystem_override.sh
@@ -0,0 +1,123 @@
+#!/bin/sh
+#
+# Darwin-only: rewrite a static archive so that consumers linking it bind
+# libc/libm symbols to Apple's libSystem instead of the bundled Zig
+# compiler-rt. This uses the Apple toolchain (xcrun, nmedit) and libSystem
+# semantics, so it must run on a Darwin host for a Darwin target.
+#
+# Background: our static library bundles Zig's compiler-rt, which defines
+# strong global implementations of libc/libm functions (memcpy, memmove,
+# memset, cos, sin, ...). When a consumer (e.g. the macOS app via the
+# XCFramework) links this archive, ld64 resolves those symbols from the
+# archive instead of libSystem, silently replacing Apple's highly
+# optimized implementations (_platform_memmove and friends, vectorized
+# libm) with compiler-rt's generic ones. We measured Zig 0.16 (LLVM 21)
+# compiler-rt memmove costing several percent of PTY throughput on
+# scroll-region workloads versus libSystem's.
+#
+# The mechanism is to localize (make non-external) the libSystem-provided
+# symbols defined by the compiler_rt.o archive member. This keeps
+# compiler_rt.o functional for the intrinsics that libSystem does NOT
+# provide (e.g. the f128 conversions ___extenddftf2/___extendxftf2, *q
+# math, sincos*) while letting every other archive member bind the
+# well-known libc/libm symbols to libSystem at final link.
+#
+# usage: libsystem_override.sh <input.a> <output.a>
+set -eu
+
+in="$1"
+out="$2"
+
+tmp="$(mktemp -d)"
+trap 'rm -rf "$tmp"' EXIT
+
+cp -f "$in" "$out"
+chmod u+w "$out"
+
+# The symbols to prefer from libSystem. Everything listed here is a
+# stable macOS export (verified against libSystem's link surface).
+# Notably NOT listed (not exported by libSystem): the *q (f128)
+# variants, sincos/sincosf/sincosl, and all ___-prefixed compiler
+# intrinsics except the fortify _chk wrappers below.
+cat >"$tmp/localize.txt" <<'EOF'
+_bcmp
+_memcmp
+_memcpy
+_memmove
+_memset
+_strlen
+___memcpy_chk
+___memmove_chk
+___memset_chk
+___strcat_chk
+___strcpy_chk
+_ceil
+_ceilf
+_ceill
+_cos
+_cosf
+_cosl
+_exp
+_exp2
+_exp2f
+_exp2l
+_expf
+_expl
+_fabs
+_fabsf
+_fabsl
+_floor
+_floorf
+_floorl
+_fma
+_fmaf
+_fmal
+_fmax
+_fmaxf
+_fmaxl
+_fmin
+_fminf
+_fminl
+_fmod
+_fmodf
+_fmodl
+_log
+_log10
+_log10f
+_log10l
+_log2
+_log2f
+_log2l
+_logf
+_logl
+_round
+_roundf
+_roundl
+_sin
+_sinf
+_sinl
+_sqrt
+_sqrtf
+_sqrtl
+_tan
+_tanf
+_tanl
+_trunc
+_truncf
+_truncl
+EOF
+
+cd "$tmp"
+
+xcrun ar x "$out" compiler_rt.o
+chmod 644 compiler_rt.o
+
+# nmedit takes a keep-list (-s): all current global definitions except
+# the ones we want to localize.
+xcrun nm -g compiler_rt.o | awk '$2 ~ /^[A-TV-Z]$/ {print $3}' | sort -u >all.txt
+sort -u localize.txt >loc.txt
+comm -23 all.txt loc.txt >keep.txt
+xcrun nmedit -s keep.txt compiler_rt.o
+
+xcrun ar r "$out" compiler_rt.o
+xcrun ranlib "$out" 2>/dev/null || true
diff --git a/src/build/mdgen/main_ghostty_1.zig b/src/build/mdgen/main_ghostty_1.zig
index 2bb413d93..e511768c9 100644
--- a/src/build/mdgen/main_ghostty_1.zig
+++ b/src/build/mdgen/main_ghostty_1.zig
@@ -1,12 +1,11 @@
 const std = @import("std");
 const gen = @import("mdgen.zig");
 
-pub fn main() !void {
-    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
-    const alloc = gpa.allocator();
+pub fn main(init: std.process.Init) !void {
+    const alloc = init.arena.allocator();
 
     var buffer: [1024]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(init.io, &buffer);
     const writer = &stdout_writer.interface;
     try gen.substitute(alloc, @embedFile("ghostty_1_header.md"), writer);
     try gen.genActions(writer);
diff --git a/src/build/mdgen/main_ghostty_5.zig b/src/build/mdgen/main_ghostty_5.zig
index 2123b0bce..4f7c4882a 100644
--- a/src/build/mdgen/main_ghostty_5.zig
+++ b/src/build/mdgen/main_ghostty_5.zig
@@ -1,12 +1,11 @@
 const std = @import("std");
 const gen = @import("mdgen.zig");
 
-pub fn main() !void {
-    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
-    const alloc = gpa.allocator();
+pub fn main(init: std.process.Init) !void {
+    const alloc = init.arena.allocator();
 
     var buffer: [1024]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(init.io, &buffer);
     const writer = &stdout_writer.interface;
     try gen.substitute(alloc, @embedFile("ghostty_5_header.md"), writer);
     try gen.genConfig(writer, false);
diff --git a/src/build/uucode_config.zig b/src/build/uucode_config.zig
index 2bb0d4508..e7a4f08c4 100644
--- a/src/build/uucode_config.zig
+++ b/src/build/uucode_config.zig
@@ -1,109 +1,138 @@
 const std = @import("std");
 const assert = std.debug.assert;
 const config = @import("config.zig");
-const config_x = @import("config.x.zig");
-const d = config.default;
-const wcwidth = config_x.wcwidth;
-const grapheme_break_no_control = config_x.grapheme_break_no_control;
 
 const Allocator = std.mem.Allocator;
 
-fn computeWidth(
-    alloc: std.mem.Allocator,
-    cp: u21,
-    data: anytype,
-    backing: anytype,
-    tracking: anytype,
-) Allocator.Error!void {
-    _ = alloc;
-    _ = cp;
-    _ = backing;
-    _ = tracking;
-
-    // This condition is needed as Ghostty currently has a singular concept for
-    // the `width` of a code point, while `uucode` splits the concept into
-    // `wcwidth_standalone` and `wcwidth_zero_in_grapheme`. The two cases where
-    // we want to use the `wcwidth_standalone` despite the code point occupying
-    // zero width in a grapheme (`wcwidth_zero_in_grapheme`) are emoji
-    // modifiers and prepend code points. For emoji modifiers we want to
-    // support displaying them in isolation as color patches, and if prepend
-    // characters were to be width 0 they would disappear from the output with
-    // Ghostty's current width 0 handling. Future work will take advantage of
-    // the new uucode `wcwidth_standalone` vs `wcwidth_zero_in_grapheme` split.
-    if (data.wcwidth_zero_in_grapheme and !data.is_emoji_modifier and data.grapheme_break_no_control != .prepend) {
-        data.width = 0;
-    } else {
-        data.width = @min(2, data.wcwidth_standalone);
-    }
-}
-
-const width = config.Extension{
-    .inputs = &.{
-        "wcwidth_standalone",
-        "wcwidth_zero_in_grapheme",
-        "is_emoji_modifier",
-        "grapheme_break_no_control",
+pub const fields = &config.mergeFields(config.fields, &.{
+    .{ .name = "width", .type = u2 },
+    .{ .name = "is_symbol", .type = bool },
+});
+pub const build_components = &config.mergeComponents(config.build_components, &.{
+    .{
+        .Impl = WidthComponent,
+        .inputs = &.{
+            "wcwidth_standalone",
+            "wcwidth_zero_in_grapheme",
+            "is_emoji_modifier",
+            "grapheme_break_no_control",
+        },
+        .fields = &.{"width"},
     },
-    .compute = &computeWidth,
-    .fields = &.{
-        .{ .name = "width", .type = u2 },
+    .{
+        .Impl = IsSymbolComponent,
+        .inputs = &.{ "block", "general_category" },
+        .fields = &.{"is_symbol"},
     },
-};
+});
 
-fn computeIsSymbol(
-    alloc: Allocator,
-    cp: u21,
-    data: anytype,
-    backing: anytype,
-    tracking: anytype,
-) Allocator.Error!void {
-    _ = alloc;
-    _ = cp;
-    _ = backing;
-    _ = tracking;
-    const block = data.block;
-    data.is_symbol = data.general_category == .other_private_use or
-        block == .arrows or
-        block == .dingbats or
-        block == .emoticons or
-        block == .miscellaneous_symbols or
-        block == .enclosed_alphanumerics or
-        block == .enclosed_alphanumeric_supplement or
-        block == .miscellaneous_symbols_and_pictographs or
-        block == .transport_and_map_symbols;
-}
-
-const is_symbol = config.Extension{
-    .inputs = &.{ "block", "general_category" },
-    .compute = &computeIsSymbol,
-    .fields = &.{
-        .{ .name = "is_symbol", .type = bool },
-    },
-};
+pub const get_components: []const config.Component = &.{};
 
 pub const tables = [_]config.Table{
     .{
         .name = "runtime",
-        .extensions = &.{},
         .fields = &.{
-            d.field("is_emoji_presentation"),
-            d.field("case_folding_full"),
+            "is_emoji_presentation",
+            "case_folding_full",
+        },
+    },
+    .{
+        // Fields that libvaxis needs that aren't included in the `runtime`
+        // table.
+        .name = "libvaxis_only",
+        .fields = &.{
+            "east_asian_width",
+            "general_category",
+            "grapheme_break",
         },
     },
     .{
         .name = "buildtime",
-        .extensions = &.{
-            wcwidth,
-            grapheme_break_no_control,
-            width,
-            is_symbol,
-        },
         .fields = &.{
-            width.field("width"),
-            wcwidth.field("wcwidth_zero_in_grapheme"),
-            grapheme_break_no_control.field("grapheme_break_no_control"),
-            is_symbol.field("is_symbol"),
-            d.field("is_emoji_vs_base"),
+            "width",
+            "wcwidth_zero_in_grapheme",
+            "grapheme_break_no_control",
+            "is_symbol",
+            "is_emoji_vs_base",
         },
     },
 };
+
+const WidthComponent = struct {
+    pub fn build(
+        comptime InputRow: type,
+        comptime Row: type,
+        allocator: std.mem.Allocator,
+        io: std.Io,
+        inputs: config.MultiSlice(InputRow),
+        rows: *config.MultiSlice(Row),
+        backing: anytype,
+        tracking: anytype,
+    ) !void {
+        _ = allocator;
+        _ = io;
+        _ = backing;
+        _ = tracking;
+
+        rows.len = config.num_code_points;
+        const items = rows.items(.width);
+        const standalone = inputs.items(.wcwidth_standalone);
+        const zero_in_grapheme = inputs.items(.wcwidth_zero_in_grapheme);
+        const is_emoji_modifier = inputs.items(.is_emoji_modifier);
+        const grapheme_break_no_control = inputs.items(.grapheme_break_no_control);
+
+        // This condition is needed as Ghostty currently has a singular concept for
+        // the `width` of a code point, while `uucode` splits the concept into
+        // `wcwidth_standalone` and `wcwidth_zero_in_grapheme`. The two cases where
+        // we want to use the `wcwidth_standalone` despite the code point occupying
+        // zero width in a grapheme (`wcwidth_zero_in_grapheme`) are emoji
+        // modifiers and prepend code points. For emoji modifiers we want to
+        // support displaying them in isolation as color patches, and if prepend
+        // characters were to be width 0 they would disappear from the output with
+        // Ghostty's current width 0 handling. Future work will take advantage of
+        // the new uucode `wcwidth_standalone` vs `wcwidth_zero_in_grapheme` split.
+        for (0..config.num_code_points) |i| {
+            if (zero_in_grapheme[i] and !is_emoji_modifier[i] and grapheme_break_no_control[i] != .prepend) {
+                items[i] = 0;
+            } else {
+                items[i] = @min(2, standalone[i]);
+            }
+        }
+    }
+};
+
+const IsSymbolComponent = struct {
+    pub fn build(
+        comptime InputRow: type,
+        comptime Row: type,
+        allocator: std.mem.Allocator,
+        io: std.Io,
+        inputs: config.MultiSlice(InputRow),
+        rows: *config.MultiSlice(Row),
+        backing: anytype,
+        tracking: anytype,
+    ) !void {
+        _ = allocator;
+        _ = io;
+        _ = backing;
+        _ = tracking;
+
+        rows.len = config.num_code_points;
+        const items = rows.items(.is_symbol);
+        const block = inputs.items(.block);
+        const general_category = inputs.items(.general_category);
+
+        for (0..config.num_code_points) |i| {
+            items[i] =
+                general_category[i] == .other_private_use or
+                block[i] == .arrows or
+                block[i] == .dingbats or
+                block[i] == .emoticons or
+                block[i] == .miscellaneous_symbols or
+                block[i] == .enclosed_alphanumerics or
+                block[i] == .enclosed_alphanumeric_supplement or
+                block[i] == .miscellaneous_symbols_and_pictographs or
+                block[i] == .transport_and_map_symbols;
+        }
+    }
+};
diff --git a/src/build/wasm_patch_growable_table.zig b/src/build/wasm_patch_growable_table.zig
index c40c0a9c8..555734aba 100644
--- a/src/build/wasm_patch_growable_table.zig
+++ b/src/build/wasm_patch_growable_table.zig
@@ -12,15 +12,13 @@ const std = @import("std");
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
 
-pub fn main() !void {
+pub fn main(init: std.process.Init) !void {
     // This is a one-off patcher, so we leak all our memory on purpose
     // and let the OS clean it up when we exit.
-    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
-    const alloc = gpa.allocator();
+    const alloc = init.arena.allocator();
 
     // Parse args: program input output
-    const args = try std.process.argsAlloc(alloc);
-    defer std.process.argsFree(alloc, args);
+    const args = try init.minimal.args.toSlice(alloc);
     if (args.len != 3) {
         std.log.err("usage: wasm_growable_table <input.wasm> <output.wasm>", .{});
         std.process.exit(1);
@@ -30,17 +28,18 @@ pub fn main() !void {
     // Patch the file.
     const output: []const u8 = try patchTableGrowable(
         alloc,
-        try std.fs.cwd().readFileAlloc(
-            alloc,
+        try std.Io.Dir.cwd().readFileAlloc(
+            init.io,
             args[1],
-            std.math.maxInt(usize),
+            alloc,
+            .unlimited,
         ),
     );
 
     // Write our output
-    const out_file = try std.fs.cwd().createFile(args[2], .{});
-    defer out_file.close();
-    try out_file.writeAll(output);
+    const out_file = try std.Io.Dir.cwd().createFile(init.io, args[2], .{});
+    defer out_file.close(init.io);
+    try out_file.writePositionalAll(init.io, output, 0);
 }
 
 /// Patch the WASM binary's table section to remove the maximum size
diff --git a/src/build/webgen/main_actions.zig b/src/build/webgen/main_actions.zig
index b0de6537d..38cda3f7a 100644
--- a/src/build/webgen/main_actions.zig
+++ b/src/build/webgen/main_actions.zig
@@ -1,9 +1,9 @@
 const std = @import("std");
 const helpgen_actions = @import("../../input/helpgen_actions.zig");
 
-pub fn main() !void {
+pub fn main(init: std.process.Init) !void {
     var buffer: [2048]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(init.io, &buffer);
     const stdout = &stdout_writer.interface;
     try helpgen_actions.generate(stdout, .markdown, true, std.heap.page_allocator);
 }
diff --git a/src/build/webgen/main_commands.zig b/src/build/webgen/main_commands.zig
index 65f144522..c895948d4 100644
--- a/src/build/webgen/main_commands.zig
+++ b/src/build/webgen/main_commands.zig
@@ -2,9 +2,9 @@ const std = @import("std");
 const Action = @import("../../cli/ghostty.zig").Action;
 const help_strings = @import("help_strings");
 
-pub fn main() !void {
+pub fn main(init: std.process.Init) !void {
     var buffer: [2048]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(init.io, &buffer);
     const stdout = &stdout_writer.interface;
     try genActions(stdout);
 }
diff --git a/src/build/webgen/main_config.zig b/src/build/webgen/main_config.zig
index 1363fadc4..82ecc950f 100644
--- a/src/build/webgen/main_config.zig
+++ b/src/build/webgen/main_config.zig
@@ -2,9 +2,9 @@ const std = @import("std");
 const Config = @import("../../config/Config.zig");
 const help_strings = @import("help_strings");
 
-pub fn main() !void {
+pub fn main(init: std.process.Init) !void {
     var buffer: [2048]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(init.io, &buffer);
     const stdout = &stdout_writer.interface;
     try genConfig(stdout);
 }
diff --git a/src/cli/Pager.zig b/src/cli/Pager.zig
index 247c998e1..1523c8858 100644
--- a/src/cli/Pager.zig
+++ b/src/cli/Pager.zig
@@ -6,29 +6,31 @@
 //! Setting either env var to an empty string disables paging.
 //! If stdout is not a TTY, writes go directly to stdout.
 const Pager = @This();
+const builtin = @import("builtin");
 const std = @import("std");
 const Allocator = std.mem.Allocator;
 const internal_os = @import("../os/main.zig");
+const global = @import("../global.zig");
 
 /// The pager child process, if one was spawned.
 child: ?std.process.Child = null,
 
 /// The buffered file writer used for both the pager pipe and direct
 /// stdout paths.
-file_writer: std.fs.File.Writer = undefined,
+file_writer: std.Io.File.Writer = undefined,
 
 /// Initialize the pager. If stdout is a TTY, this spawns the pager
 /// process. Otherwise, output goes directly to stdout.
-pub fn init(alloc: Allocator) Pager {
-    return .{ .child = initPager(alloc) };
+pub fn init() Pager {
+    return .{ .child = initPager() };
 }
 
 /// Writes to the pager process if available; otherwise, stdout.
 pub fn writer(self: *Pager, buffer: []u8) *std.Io.Writer {
     if (self.child) |child| {
-        self.file_writer = child.stdin.?.writer(buffer);
+        self.file_writer = child.stdin.?.writer(global.io(), buffer);
     } else {
-        self.file_writer = std.fs.File.stdout().writer(buffer);
+        self.file_writer = std.Io.File.stdout().writer(global.io(), buffer);
     }
     return &self.file_writer.interface;
 }
@@ -40,45 +42,44 @@ pub fn deinit(self: *Pager) void {
         // pager sees EOF, then wait for it to exit.
         self.file_writer.interface.flush() catch {};
         if (child.stdin) |stdin| {
-            stdin.close();
+            stdin.close(global.io());
             child.stdin = null;
         }
-        _ = child.wait() catch {};
+        _ = child.wait(global.io()) catch {};
     }
 
     self.* = undefined;
 }
 
-fn initPager(alloc: Allocator) ?std.process.Child {
-    const stdout_file: std.fs.File = .stdout();
-    if (!stdout_file.isTty()) return null;
+fn initPager() ?std.process.Child {
+    const stdout_file: std.Io.File = .stdout();
+    if (!(stdout_file.isTty(global.io()) catch return null)) return null;
+
+    var env = global.environMap() catch return null;
+    defer env.deinit();
 
     // Resolve the pager command: $GHOSTTY_PAGER > $PAGER > `less`.
     // An empty value for either env var disables paging.
-    const ghostty_var = internal_os.getenv(alloc, "GHOSTTY_PAGER") catch null;
-    defer if (ghostty_var) |v| v.deinit(alloc);
-    const pager_var = internal_os.getenv(alloc, "PAGER") catch null;
-    defer if (pager_var) |v| v.deinit(alloc);
-
+    const ghostty_var = env.get("GHOSTTY_PAGER");
+    const pager_var = env.get("PAGER");
     const cmd: ?[]const u8 = cmd: {
-        if (ghostty_var) |v| break :cmd if (v.value.len > 0) v.value else null;
-        if (pager_var) |v| break :cmd if (v.value.len > 0) v.value else null;
+        if (ghostty_var) |v| break :cmd if (v.len > 0) v else null;
+        if (pager_var) |v| break :cmd if (v.len > 0) v else null;
         break :cmd "less";
     };
 
     if (cmd == null) return null;
 
-    var child: std.process.Child = .init(&.{cmd.?}, alloc);
-    child.stdin_behavior = .Pipe;
-    child.stdout_behavior = .Inherit;
-    child.stderr_behavior = .Inherit;
-
-    child.spawn() catch return null;
-    return child;
+    return std.process.spawn(global.io(), .{
+        .argv = &.{cmd.?},
+        .stdin = .pipe,
+        .stdout = .inherit,
+        .stderr = .inherit,
+    }) catch null;
 }
 
 test "pager: non-tty" {
-    var pager: Pager = .init(std.testing.allocator);
+    var pager: Pager = .init();
     defer pager.deinit();
     try std.testing.expect(pager.child == null);
 }
diff --git a/src/cli/action.zig b/src/cli/action.zig
index 41173a9f1..6cedaa096 100644
--- a/src/cli/action.zig
+++ b/src/cli/action.zig
@@ -11,8 +11,8 @@ pub const DetectError = error{
 };
 
 /// Detect the action from CLI args.
-pub fn detectArgs(comptime E: type, alloc: Allocator) !?E {
-    var iter = try std.process.argsWithAllocator(alloc);
+pub fn detectArgs(comptime E: type, alloc: Allocator, args: std.process.Args) !?E {
+    var iter = try args.iterateAllocator(alloc);
     defer iter.deinit();
     return try detectIter(E, &iter);
 }
@@ -83,7 +83,7 @@ test "detect direct match" {
     const alloc = testing.allocator;
     const Enum = enum { foo, bar, baz };
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         alloc,
         "+foo",
     );
@@ -97,7 +97,7 @@ test "detect invalid match" {
     const alloc = testing.allocator;
     const Enum = enum { foo, bar, baz };
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         alloc,
         "+invalid",
     );
@@ -113,7 +113,7 @@ test "detect multiple actions" {
     const alloc = testing.allocator;
     const Enum = enum { foo, bar, baz };
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         alloc,
         "+foo +bar",
     );
@@ -129,7 +129,7 @@ test "detect no match" {
     const alloc = testing.allocator;
     const Enum = enum { foo, bar, baz };
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         alloc,
         "--some-flag",
     );
@@ -154,7 +154,7 @@ test "detect special case action" {
     };
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--special +bar",
         );
@@ -164,7 +164,7 @@ test "detect special case action" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "+bar --special",
         );
@@ -174,7 +174,7 @@ test "detect special case action" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "+bar",
         );
@@ -200,7 +200,7 @@ test "detect special case fallback" {
     };
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--special",
         );
@@ -210,7 +210,7 @@ test "detect special case fallback" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "+bar --special",
         );
@@ -220,7 +220,7 @@ test "detect special case fallback" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--special +bar",
         );
@@ -246,7 +246,7 @@ test "detect special case abort_if_no_action" {
     };
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "-e",
         );
@@ -256,7 +256,7 @@ test "detect special case abort_if_no_action" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "+foo -e",
         );
@@ -266,7 +266,7 @@ test "detect special case abort_if_no_action" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "-e +bar",
         );
diff --git a/src/cli/args.zig b/src/cli/args.zig
index bd5060d69..d73277fda 100644
--- a/src/cli/args.zig
+++ b/src/cli/args.zig
@@ -489,18 +489,13 @@ pub fn parseTaggedUnion(comptime T: type, alloc: Allocator, v: []const u8) !T {
 
             // We need to create a struct that looks like this union field.
             // This lets us use parseIntoField as if its a dedicated struct.
-            const Target = @Type(.{ .@"struct" = .{
-                .layout = .auto,
-                .fields = &.{.{
-                    .name = field.name,
-                    .type = field.type,
-                    .default_value_ptr = null,
-                    .is_comptime = false,
-                    .alignment = @alignOf(field.type),
-                }},
-                .decls = &.{},
-                .is_tuple = false,
-            } });
+            const Target = @Struct(
+                .auto,
+                null,
+                &.{field.name},
+                &.{field.type},
+                &.{.{ .@"align" = @alignOf(field.type) }},
+            );
 
             // Parse the value into the struct
             var t: Target = undefined;
@@ -677,7 +672,7 @@ test "parse: simple" {
     } = .{};
     defer if (data._arena) |arena| arena.deinit();
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--a=42 --b --b-f=false",
     );
@@ -689,7 +684,7 @@ test "parse: simple" {
     try testing.expect(!data.@"b-f");
 
     // Reparsing works
-    var iter2 = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter2 = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--a=84",
     );
@@ -711,7 +706,7 @@ test "parse: quoted value" {
     } = .{};
     defer if (data._arena) |arena| arena.deinit();
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--a=\"42\" --b=\"hello!\"",
     );
@@ -731,7 +726,7 @@ test "parse: empty value resets to default" {
     } = .{};
     defer if (data._arena) |arena| arena.deinit();
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--a= --b=",
     );
@@ -750,7 +745,7 @@ test "parse: positional arguments are invalid" {
     } = .{};
     defer if (data._arena) |arena| arena.deinit();
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--a=84 what",
     );
@@ -774,7 +769,7 @@ test "parse: diagnostic tracking" {
     } = .{};
     defer if (data._arena) |arena| arena.deinit();
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--what --a=42",
     );
@@ -858,7 +853,7 @@ test "parse: compatibility handler" {
     } = .{};
     defer if (data._arena) |arena| arena.deinit();
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--a=yuh",
     );
@@ -884,7 +879,7 @@ test "parse: compatibility renamed" {
     } = .{};
     defer if (data._arena) |arena| arena.deinit();
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--old=true --b=true",
     );
@@ -1363,8 +1358,11 @@ pub fn ArgsIterator(comptime Iterator: type) type {
 }
 
 /// Create an args iterator for the process args. This will skip argv0.
-pub fn argsIterator(alloc_gpa: Allocator) internal_os.args.ArgIterator.InitError!ArgsIterator(internal_os.args.ArgIterator) {
-    var iter = try internal_os.args.iterator(alloc_gpa);
+pub fn argsIterator(
+    alloc_gpa: Allocator,
+    args: std.process.Args,
+) std.process.Args.Iterator.InitError!ArgsIterator(std.process.Args.Iterator) {
+    var iter: std.process.Args.Iterator = try .initAllocator(args, alloc_gpa);
     errdefer iter.deinit();
     _ = iter.next(); // skip argv0
     return .{ .iterator = iter };
@@ -1373,7 +1371,7 @@ pub fn argsIterator(alloc_gpa: Allocator) internal_os.args.ArgIterator.InitError
 test "ArgsIterator" {
     const testing = std.testing;
 
-    const child = try std.process.ArgIteratorGeneral(.{}).init(
+    const child = try std.process.Args.IteratorGeneral(.{}).init(
         testing.allocator,
         "--what +list-things --a=42",
     );
diff --git a/src/cli/boo.zig b/src/cli/boo.zig
index 2834eadbd..a33d56ae5 100644
--- a/src/cli/boo.zig
+++ b/src/cli/boo.zig
@@ -3,6 +3,7 @@ const builtin = @import("builtin");
 const args = @import("args.zig");
 const Action = @import("ghostty.zig").Action;
 const Allocator = std.mem.Allocator;
+const global = @import("../global.zig");
 const vaxis = @import("vaxis");
 
 const framedata = @import("framedata").compressed;
@@ -173,6 +174,9 @@ const Boo = struct {
 
 /// The `boo` command is used to display the animation from the Ghostty website in the terminal
 pub fn run(gpa: Allocator) !u8 {
+    var env_map = try global.environMap();
+    defer env_map.deinit();
+
     // Disable on non-desktop systems.
     switch (builtin.os.tag) {
         .windows, .macos, .linux, .freebsd => {},
@@ -183,7 +187,7 @@ pub fn run(gpa: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(gpa);
+        var iter = try args.argsIterator(gpa, global.args());
         defer iter.deinit();
         try args.parse(Options, gpa, &opts, &iter);
     }
@@ -194,7 +198,7 @@ pub fn run(gpa: Allocator) !u8 {
         gpa.free(decompressed_data);
     }
 
-    var app = try vxfw.App.init(gpa);
+    var app = try vxfw.App.init(global.io(), gpa, &env_map, &.{});
     defer app.deinit();
 
     var boo: Boo = undefined;
diff --git a/src/cli/crash_report.zig b/src/cli/crash_report.zig
index f0940fdab..2c0484e96 100644
--- a/src/cli/crash_report.zig
+++ b/src/cli/crash_report.zig
@@ -4,6 +4,7 @@ const args = @import("args.zig");
 const Action = @import("ghostty.zig").Action;
 const Config = @import("../config.zig").Config;
 const crash = @import("../crash/main.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
     pub fn deinit(self: Options) void {
@@ -33,14 +34,14 @@ pub fn run(alloc_gpa: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc_gpa);
+        var iter = try args.argsIterator(alloc_gpa, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc_gpa, &opts, &iter);
     }
 
     var buffer: [1024]u8 = undefined;
-    var stdout_file: std.fs.File = .stdout();
-    var stdout_writer = stdout_file.writer(&buffer);
+    var stdout_file: std.Io.File = .stdout();
+    var stdout_writer = stdout_file.writer(global.io(), &buffer);
     const stdout = &stdout_writer.interface;
 
     const result = runInner(alloc, &stdout_file, stdout);
@@ -50,7 +51,7 @@ pub fn run(alloc_gpa: Allocator) !u8 {
 
 fn runInner(
     alloc: Allocator,
-    stdout_file: *std.fs.File,
+    stdout_file: *std.Io.File,
     stdout: *std.Io.Writer,
 ) !u8 {
     const crash_dir = try crash.defaultDir(alloc);
@@ -66,7 +67,7 @@ fn runInner(
     // If we have no reports, then we're done. If we have a tty then we
     // print a message, otherwise we do nothing.
     if (reports.items.len == 0) {
-        if (std.posix.isatty(stdout_file.handle)) {
+        if (try stdout_file.isTty(global.io())) {
             try stdout.writeAll("No crash reports! 👻\n");
         }
         return 0;
@@ -76,7 +77,7 @@ fn runInner(
 
     for (reports.items) |report| {
         var buf: [128]u8 = undefined;
-        const now = std.time.nanoTimestamp();
+        const now = std.Io.Timestamp.now(global.io(), .real).toNanoseconds();
         const diff = now - report.mtime;
         const since = if (diff <= 0) "now" else s: {
             const d = Config.Duration{ .duration = @intCast(diff) };
diff --git a/src/cli/diagnostics.zig b/src/cli/diagnostics.zig
index 7f4dcc45e..0e4048a01 100644
--- a/src/cli/diagnostics.zig
+++ b/src/cli/diagnostics.zig
@@ -93,7 +93,7 @@ pub const Location = union(enum) {
 /// and potentially in the future structure them differently.
 pub const DiagnosticList = struct {
     /// The list of diagnostics.
-    list: std.ArrayListUnmanaged(Diagnostic) = .{},
+    list: std.ArrayList(Diagnostic) = .empty,
 
     /// Precomputed data for diagnostics. This is used specifically
     /// when we build libghostty so that we can precompute the messages
@@ -111,7 +111,7 @@ pub const DiagnosticList = struct {
     };
 
     const Precompute = if (precompute_enabled) struct {
-        messages: std.ArrayListUnmanaged([:0]const u8) = .{},
+        messages: std.ArrayList([:0]const u8) = .empty,
 
         pub fn clone(
             self: *const Precompute,
diff --git a/src/cli/edit_config.zig b/src/cli/edit_config.zig
index c08651a06..9662ea444 100644
--- a/src/cli/edit_config.zig
+++ b/src/cli/edit_config.zig
@@ -7,6 +7,7 @@ const Action = @import("ghostty.zig").Action;
 const configpkg = @import("../config.zig");
 const internal_os = @import("../os/main.zig");
 const Config = configpkg.Config;
+const global = @import("../global.zig");
 
 pub const Options = struct {
     pub fn deinit(self: Options) void {
@@ -48,14 +49,14 @@ pub fn run(alloc: Allocator) !u8 {
     // critical where setting up the defer cleanup is a problem.
 
     var buffer: [1024]u8 = undefined;
-    var stderr_writer = std.fs.File.stderr().writer(&buffer);
+    var stderr_writer = std.Io.File.stderr().writer(global.io(), &buffer);
     const stderr = &stderr_writer.interface;
 
     var opts: Options = .{};
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc);
+        var iter = try args.argsIterator(alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc, &opts, &iter);
     }
@@ -67,6 +68,12 @@ pub fn run(alloc: Allocator) !u8 {
 }
 
 fn runInner(alloc: Allocator, stderr: *std.Io.Writer) !u8 {
+    // We require libc because we want to use std.c.environ for envp
+    // and not have to build that ourselves. We can remove this
+    // limitation later but Ghostty already heavily requires libc
+    // so this is not a big deal.
+    comptime assert(builtin.link_libc);
+
     // We load the configuration once because that will write our
     // default configuration files to disk. We don't use the config.
     var config = try Config.load(alloc);
@@ -91,22 +98,19 @@ fn runInner(alloc: Allocator, stderr: *std.Io.Writer) !u8 {
     }
 
     // Get our editor
-    const get_env_: ?internal_os.GetEnvResult = env: {
+    const editor = env: {
         // VISUAL vs. EDITOR: https://unix.stackexchange.com/questions/4859/visual-vs-editor-what-s-the-difference
-        if (try internal_os.getenv(alloc, "VISUAL")) |v| {
-            if (v.value.len > 0) break :env v;
-            v.deinit(alloc);
+        if (try global.environ().containsUnempty(alloc, "VISUAL")) {
+            break :env try global.environ().getAlloc(alloc, "VISUAL");
         }
 
-        if (try internal_os.getenv(alloc, "EDITOR")) |v| {
-            if (v.value.len > 0) break :env v;
-            v.deinit(alloc);
+        if (try global.environ().containsUnempty(alloc, "EDITOR")) {
+            break :env try global.environ().getAlloc(alloc, "EDITOR");
         }
 
-        break :env null;
+        break :env "";
     };
-    defer if (get_env_) |v| v.deinit(alloc);
-    const editor: []const u8 = if (get_env_) |v| v.value else "";
+    defer alloc.free(editor);
 
     // If we don't have `$EDITOR` set then we can't do anything
     // but we can still print a helpful message.
@@ -136,8 +140,9 @@ fn runInner(alloc: Allocator, stderr: *std.Io.Writer) !u8 {
         return 1;
     }
 
+    // Build the command
     const command = command: {
-        var buffer: std.io.Writer.Allocating = .init(alloc);
+        var buffer: std.Io.Writer.Allocating = .init(alloc);
         defer buffer.deinit();
         const writer = &buffer.writer;
         try writer.writeAll(editor);
@@ -152,21 +157,18 @@ fn runInner(alloc: Allocator, stderr: *std.Io.Writer) !u8 {
     };
     defer alloc.free(command);
 
-    // We require libc because we want to use std.c.environ for envp
-    // and not have to build that ourselves. We can remove this
-    // limitation later but Ghostty already heavily requires libc
-    // so this is not a big deal.
-    comptime assert(builtin.link_libc);
-
-    const err = std.posix.execvpeZ(
+    // Run/replace process (using execve)
+    const argv = [_:null]?[*:0]const u8{
         "/bin/sh",
-        &.{ "/bin/sh", "-c", command },
-        std.c.environ,
-    );
+        "-c",
+        command.ptr,
+    };
+    const envp = std.c.environ;
+    const err = std.posix.errno(std.posix.system.execve(argv[0].?, &argv, envp));
 
     // If we reached this point then exec failed.
     try stderr.print(
-        \\Failed to execute the editor. Error code={}.
+        \\Failed to execute the editor (E{s}).
         \\
         \\This is usually due to the executable path not existing, invalid
         \\permissions, or the shell environment not being set up
@@ -175,6 +177,6 @@ fn runInner(alloc: Allocator, stderr: *std.Io.Writer) !u8 {
         \\Editor: {s}
         \\Path: {s}
         \\
-    , .{ err, editor, path });
+    , .{ @tagName(err), editor, path });
     return 1;
 }
diff --git a/src/cli/explain_config.zig b/src/cli/explain_config.zig
index 4f034afef..6f03256d6 100644
--- a/src/cli/explain_config.zig
+++ b/src/cli/explain_config.zig
@@ -7,6 +7,7 @@ const Config = @import("../config/Config.zig");
 const ConfigKey = @import("../config/key.zig").Key;
 const KeybindAction = @import("../input/Binding.zig").Action;
 const Pager = @import("Pager.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// The config option to explain. For example:
@@ -51,7 +52,7 @@ pub fn run(alloc: Allocator) !u8 {
     var positional: ?[]const u8 = null;
     var no_pager: bool = false;
 
-    var iter = try args.argsIterator(alloc);
+    var iter = try args.argsIterator(alloc, global.args());
     defer iter.deinit();
     defer if (option_name) |s| alloc.free(s);
     defer if (keybind_name) |s| alloc.free(s);
@@ -75,9 +76,9 @@ pub fn run(alloc: Allocator) !u8 {
     // respective lookup. A bare positional argument tries config
     // options first, then keybind actions as a fallback.
     const name = keybind_name orelse option_name orelse positional orelse {
-        var stderr: std.fs.File = .stderr();
+        var stderr: std.Io.File = .stderr();
         var buffer: [4096]u8 = undefined;
-        var stderr_writer = stderr.writer(&buffer);
+        var stderr_writer = stderr.writer(global.io(), &buffer);
         try stderr_writer.interface.writeAll("Usage: ghostty +explain-config <option>\n");
         try stderr_writer.interface.writeAll("       ghostty +explain-config --option=<option>\n");
         try stderr_writer.interface.writeAll("       ghostty +explain-config --keybind=<action>\n");
@@ -92,7 +93,7 @@ pub fn run(alloc: Allocator) !u8 {
     else
         explainOption(name) orelse explainKeybind(name);
 
-    var pager: Pager = if (!no_pager) .init(alloc) else .{};
+    var pager: Pager = if (!no_pager) .init() else .{};
     defer pager.deinit();
     var buffer: [4096]u8 = undefined;
     const writer = pager.writer(&buffer);
diff --git a/src/cli/ghostty.zig b/src/cli/ghostty.zig
index 6e836851b..77dbe5ab5 100644
--- a/src/cli/ghostty.zig
+++ b/src/cli/ghostty.zig
@@ -22,6 +22,7 @@ const show_face = @import("show_face.zig");
 const boo = @import("boo.zig");
 const new_window = @import("new_window.zig");
 const toggle_quick_terminal = @import("toggle_quick_terminal.zig");
+const global = @import("../global.zig");
 
 /// Special commands that can be invoked via CLI flags. These are all
 /// invoked by using `+<action>` as a CLI flag. The only exception is
@@ -120,7 +121,10 @@ pub const Action = enum {
 
                     if (std.mem.eql(u8, field.name, @tagName(self))) {
                         var buffer: [1024]u8 = undefined;
-                        var stdout_writer = std.fs.File.stdout().writer(&buffer);
+                        var stdout_writer = std.Io.File.stdout().writer(
+                            global.io(),
+                            &buffer,
+                        );
                         const stdout = &stdout_writer.interface;
                         const text = @field(help_strings.Action, field.name) ++ "\n";
                         stdout.writeAll(text) catch |write_err| {
@@ -213,7 +217,7 @@ test "parse action none" {
     const testing = std.testing;
     const alloc = testing.allocator;
 
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(
         alloc,
         "--a=42 --b --b-f=false",
     );
@@ -227,7 +231,7 @@ test "parse action version" {
     const alloc = testing.allocator;
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--a=42 --b --b-f=false --version",
         );
@@ -237,7 +241,7 @@ test "parse action version" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--version --a=42 --b --b-f=false",
         );
@@ -247,7 +251,7 @@ test "parse action version" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--c=84 --d --version --a=42 --b --b-f=false",
         );
@@ -262,7 +266,7 @@ test "parse action plus" {
     const alloc = testing.allocator;
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--a=42 --b --b-f=false +version",
         );
@@ -272,7 +276,7 @@ test "parse action plus" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "+version --a=42 --b --b-f=false",
         );
@@ -282,7 +286,7 @@ test "parse action plus" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--c=84 --d +version --a=42 --b --b-f=false",
         );
@@ -297,7 +301,7 @@ test "parse action plus ignores -e" {
     const alloc = testing.allocator;
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "--a=42 -e +version",
         );
@@ -307,7 +311,7 @@ test "parse action plus ignores -e" {
     }
 
     {
-        var iter = try std.process.ArgIteratorGeneral(.{}).init(
+        var iter = try std.process.Args.IteratorGeneral(.{}).init(
             alloc,
             "+list-fonts --a=42 -e +version",
         );
diff --git a/src/cli/help.zig b/src/cli/help.zig
index a2b4dde80..755aa127b 100644
--- a/src/cli/help.zig
+++ b/src/cli/help.zig
@@ -2,6 +2,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const args = @import("args.zig");
 const Action = @import("ghostty.zig").Action;
+const global = @import("../global.zig");
 
 // Note that this options struct doesn't implement the `help` decl like other
 // actions. That is because the help command is special and wants to handle its
@@ -25,13 +26,13 @@ pub fn run(alloc: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc);
+        var iter = try args.argsIterator(alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc, &opts, &iter);
     }
 
     var buffer: [2048]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(global.io(), &buffer);
     const stdout = &stdout_writer.interface;
     try stdout.writeAll(
         \\Usage: ghostty [+action] [options]
diff --git a/src/cli/list_actions.zig b/src/cli/list_actions.zig
index aaef1195e..ce4af5c49 100644
--- a/src/cli/list_actions.zig
+++ b/src/cli/list_actions.zig
@@ -3,6 +3,7 @@ const args = @import("args.zig");
 const Action = @import("ghostty.zig").Action;
 const Allocator = std.mem.Allocator;
 const helpgen_actions = @import("../input/helpgen_actions.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// If `true`, print out documentation about the action associated with the
@@ -32,14 +33,14 @@ pub fn run(alloc: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc);
+        var iter = try args.argsIterator(alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc, &opts, &iter);
     }
 
-    var stdout: std.fs.File = .stdout();
+    var stdout: std.Io.File = .stdout();
     var buffer: [4096]u8 = undefined;
-    var stdout_writer = stdout.writer(&buffer);
+    var stdout_writer = stdout.writer(global.io(), &buffer);
     try helpgen_actions.generate(
         &stdout_writer.interface,
         .plaintext,
diff --git a/src/cli/list_colors.zig b/src/cli/list_colors.zig
index 50c12a693..cd76a1fbd 100644
--- a/src/cli/list_colors.zig
+++ b/src/cli/list_colors.zig
@@ -6,6 +6,7 @@ const args = @import("args.zig");
 const x11_color = @import("../terminal/main.zig").x11_color;
 const vaxis = @import("vaxis");
 const tui = @import("tui.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
     pub fn deinit(self: Options) void {
@@ -34,7 +35,7 @@ pub fn run(alloc: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc);
+        var iter = try args.argsIterator(alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc, &opts, &iter);
     }
@@ -49,15 +50,14 @@ pub fn run(alloc: Allocator) !u8 {
         }
     }.lessThan);
 
-    // Despite being under the posix namespace, this also works on Windows as of zig 0.13.0
-    var stdout: std.fs.File = .stdout();
-    if (tui.can_pretty_print and !opts.plain and std.posix.isatty(stdout.handle)) {
+    var stdout: std.Io.File = .stdout();
+    if (tui.can_pretty_print and !opts.plain and try stdout.isTty(global.io())) {
         var arena = std.heap.ArenaAllocator.init(alloc);
         defer arena.deinit();
         return prettyPrint(arena.allocator(), keys.items);
     } else {
         var buffer: [4096]u8 = undefined;
-        var stdout_writer = stdout.writer(&buffer);
+        var stdout_writer = stdout.writer(global.io(), &buffer);
         const writer = &stdout_writer.interface;
         for (keys.items) |name| {
             const rgb = x11_color.map.get(name).?;
@@ -74,11 +74,14 @@ pub fn run(alloc: Allocator) !u8 {
 }
 
 fn prettyPrint(alloc: Allocator, keys: [][]const u8) !u8 {
+    var env_map = try global.environMap();
+    defer env_map.deinit();
+
     // Set up vaxis
     var buf: [1024]u8 = undefined;
-    var tty = try vaxis.Tty.init(&buf);
+    var tty = try vaxis.Tty.init(global.io(), &buf);
     defer tty.deinit();
-    var vx = try vaxis.init(alloc, .{});
+    var vx = try vaxis.init(global.io(), alloc, &env_map, .{});
     defer vx.deinit(alloc, tty.writer());
 
     // We know we are ghostty, so let's enable mode 2027. Vaxis normally does this but you need an
@@ -97,7 +100,7 @@ fn prettyPrint(alloc: Allocator, keys: [][]const u8) !u8 {
             .y_pixel = 768,
         },
 
-        else => try vaxis.Tty.getWinsize(tty.fd),
+        else => try tty.getWinsize(),
     };
     try vx.resize(alloc, tty.writer(), winsize);
 
diff --git a/src/cli/list_fonts.zig b/src/cli/list_fonts.zig
index 6e08aa838..7cfce715c 100644
--- a/src/cli/list_fonts.zig
+++ b/src/cli/list_fonts.zig
@@ -4,6 +4,7 @@ const ArenaAllocator = std.heap.ArenaAllocator;
 const Action = @import("ghostty.zig").Action;
 const args = @import("args.zig");
 const font = @import("../font/main.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.list_fonts);
 
@@ -60,7 +61,7 @@ pub const Options = struct {
 ///     is identical to the `font-family` set of Ghostty configuration values, so
 ///     this can be used to debug why your desired font may not be loading.
 pub fn run(alloc: Allocator) !u8 {
-    var iter = try args.argsIterator(alloc);
+    var iter = try args.argsIterator(alloc, global.args());
     defer iter.deinit();
     return try runArgs(alloc, &iter);
 }
@@ -78,7 +79,7 @@ fn runArgs(alloc_gpa: Allocator, argsIter: anytype) !u8 {
     // Its possible to build Ghostty without font discovery!
     if (comptime font.Discover == void) {
         var buffer: [1024]u8 = undefined;
-        var stderr_writer = std.fs.File.stderr().writer(&buffer);
+        var stderr_writer = std.Io.File.stderr().writer(global.io(), &buffer);
         const stderr = &stderr_writer.interface;
         try stderr.print(
             \\Ghostty was built without a font discovery mechanism. This is a compile-time
@@ -92,7 +93,7 @@ fn runArgs(alloc_gpa: Allocator, argsIter: anytype) !u8 {
     }
 
     var buffer: [2048]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(global.io(), &buffer);
     const stdout = &stdout_writer.interface;
 
     // We'll be putting our fonts into a list categorized by family
@@ -133,7 +134,7 @@ fn runArgs(alloc_gpa: Allocator, argsIter: anytype) !u8 {
         const gop = try map.getOrPut(family);
         if (!gop.found_existing) {
             try families.append(alloc, family);
-            gop.value_ptr.* = .{};
+            gop.value_ptr.* = .empty;
         }
         try gop.value_ptr.append(alloc, full_name);
     }
diff --git a/src/cli/list_keybinds.zig b/src/cli/list_keybinds.zig
index 61050d0cb..f8a2663ca 100644
--- a/src/cli/list_keybinds.zig
+++ b/src/cli/list_keybinds.zig
@@ -10,6 +10,7 @@ const vaxis = @import("vaxis");
 const input = @import("../input.zig");
 const tui = @import("tui.zig");
 const Binding = input.Binding;
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// If `true`, print out the default keybinds instead of the ones configured
@@ -56,7 +57,7 @@ pub fn run(alloc: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc);
+        var iter = try args.argsIterator(alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc, &opts, &iter);
     }
@@ -65,11 +66,11 @@ pub fn run(alloc: Allocator) !u8 {
     defer config.deinit();
 
     var buffer: [1024]u8 = undefined;
-    const stdout: std.fs.File = .stdout();
-    var stdout_writer = stdout.writer(&buffer);
+    const stdout: std.Io.File = .stdout();
+    var stdout_writer = stdout.writer(global.io(), &buffer);
     const writer = &stdout_writer.interface;
 
-    if (tui.can_pretty_print and !opts.plain and stdout.isTty()) {
+    if (tui.can_pretty_print and !opts.plain and try stdout.isTty(global.io())) {
         var arena = std.heap.ArenaAllocator.init(alloc);
         defer arena.deinit();
         return prettyPrint(arena.allocator(), config.keybind);
@@ -218,11 +219,14 @@ const ChordBinding = struct {
 };
 
 fn prettyPrint(alloc: Allocator, keybinds: Config.Keybinds) !u8 {
+    var env_map = try global.environMap();
+    defer env_map.deinit();
+
     // Set up vaxis
     var buf: [1024]u8 = undefined;
-    var tty = try vaxis.Tty.init(&buf);
+    var tty = try vaxis.Tty.init(global.io(), &buf);
     defer tty.deinit();
-    var vx = try vaxis.init(alloc, .{});
+    var vx = try vaxis.init(global.io(), alloc, &env_map, .{});
     const writer = tty.writer();
     defer vx.deinit(alloc, writer);
 
@@ -242,7 +246,7 @@ fn prettyPrint(alloc: Allocator, keybinds: Config.Keybinds) !u8 {
             .y_pixel = 768,
         },
 
-        else => try vaxis.Tty.getWinsize(tty.fd),
+        else => try tty.getWinsize(),
     };
     try vx.resize(alloc, writer, winsize);
 
diff --git a/src/cli/list_themes.zig b/src/cli/list_themes.zig
index 42aff9d56..4e619cdd3 100644
--- a/src/cli/list_themes.zig
+++ b/src/cli/list_themes.zig
@@ -5,7 +5,7 @@ const Config = @import("../config/Config.zig");
 const configpkg = @import("../config.zig");
 const themepkg = @import("../config/theme.zig");
 const tui = @import("tui.zig");
-const global_state = &@import("../global.zig").state;
+const global = @import("../global.zig");
 
 const vaxis = @import("vaxis");
 const zf = @import("zf");
@@ -108,7 +108,7 @@ pub fn run(gpa_alloc: std.mem.Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(gpa_alloc);
+        var iter = try args.argsIterator(gpa_alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, gpa_alloc, &opts, &iter);
     }
@@ -117,15 +117,15 @@ pub fn run(gpa_alloc: std.mem.Allocator) !u8 {
     const alloc = arena.allocator();
 
     var stdout_buf: [4096]u8 = undefined;
-    var stdout_file: std.fs.File = .stdout();
-    var stdout_writer = stdout_file.writer(&stdout_buf);
+    var stdout_file: std.Io.File = .stdout();
+    var stdout_writer = stdout_file.writer(global.io(), &stdout_buf);
     const stdout = &stdout_writer.interface;
 
     var stderr_buf: [4096]u8 = undefined;
-    var stderr_writer = std.fs.File.stderr().writer(&stderr_buf);
+    var stderr_writer = std.Io.File.stderr().writer(global.io(), &stderr_buf);
     const stderr = &stderr_writer.interface;
 
-    const resources_dir = global_state.resources_dir.app();
+    const resources_dir = global.resourcesDir().app();
     if (resources_dir == null)
         try stderr.print("Could not find the Ghostty resources directory. Please ensure " ++
             "that Ghostty is installed correctly.\n", .{});
@@ -137,18 +137,22 @@ pub fn run(gpa_alloc: std.mem.Allocator) !u8 {
     var it: themepkg.LocationIterator = .{ .arena_alloc = arena.allocator() };
 
     while (try it.next()) |loc| {
-        var dir = std.fs.cwd().openDir(loc.dir, .{ .iterate = true }) catch |err| switch (err) {
+        var dir = std.Io.Dir.cwd().openDir(
+            global.io(),
+            loc.dir,
+            .{ .iterate = true },
+        ) catch |err| switch (err) {
             error.FileNotFound => continue,
             else => {
                 std.debug.print("error trying to open {s}: {}\n", .{ loc.dir, err });
                 continue;
             },
         };
-        defer dir.close();
+        defer dir.close(global.io());
 
         var walker = dir.iterate();
 
-        while (try walker.next()) |entry| {
+        while (try walker.next(global.io())) |entry| {
             switch (entry.kind) {
                 .file, .sym_link => {
                     if (std.mem.eql(u8, entry.name, ".DS_Store"))
@@ -174,7 +178,7 @@ pub fn run(gpa_alloc: std.mem.Allocator) !u8 {
 
     std.mem.sortUnstable(ThemeListElement, themes.items, {}, ThemeListElement.lessThan);
 
-    if (tui.can_pretty_print and !opts.plain and stdout_file.isTty()) {
+    if (tui.can_pretty_print and !opts.plain and try stdout_file.isTty(global.io())) {
         try preview(gpa_alloc, themes.items, opts.color);
         return 0;
     }
@@ -210,14 +214,18 @@ fn writeAutoThemeFile(alloc: std.mem.Allocator, theme_name: []const u8) !void {
     defer alloc.free(auto_path);
 
     if (std.fs.path.dirname(auto_path)) |dir| {
-        try std.fs.cwd().makePath(dir);
+        try std.Io.Dir.cwd().createDirPath(global.io(), dir);
     }
 
-    var f = try std.fs.createFileAbsolute(auto_path, .{ .truncate = true });
-    defer f.close();
+    var f = try std.Io.Dir.createFileAbsolute(
+        global.io(),
+        auto_path,
+        .{ .truncate = true },
+    );
+    defer f.close(global.io());
 
     var buf: [128]u8 = undefined;
-    var w = f.writer(&buf);
+    var w = f.writer(global.io(), &buf);
     try w.interface.print("theme = {s}\n", .{theme_name});
     try w.interface.flush();
 }
@@ -256,13 +264,16 @@ const Preview = struct {
         theme_filter: ColorScheme,
         buf: []u8,
     ) !*Preview {
+        var env_map = try global.environMap();
+        defer env_map.deinit();
+
         const self = try allocator.create(Preview);
 
         self.* = .{
             .allocator = allocator,
             .should_quit = false,
-            .tty = try .init(buf),
-            .vx = try vaxis.init(allocator, .{}),
+            .tty = try .init(global.io(), buf),
+            .vx = try vaxis.init(global.io(), allocator, &env_map, .{}),
             .mouse = null,
             .themes = themes,
             .filtered = try .initCapacity(allocator, themes.len),
@@ -290,18 +301,12 @@ const Preview = struct {
     }
 
     pub fn run(self: *Preview) !void {
-        var loop: vaxis.Loop(Event) = .{
-            .tty = &self.tty,
-            .vaxis = &self.vx,
-        };
-        try loop.init();
-        try loop.start();
-
+        var loop: vaxis.Loop(Event) = .init(global.io(), &self.tty, &self.vx);
         const writer = self.tty.writer();
 
         try self.vx.enterAltScreen(writer);
         try self.vx.setTitle(writer, "👻 Ghostty Theme Preview 👻");
-        try self.vx.queryTerminal(writer, 1 * std.time.ns_per_s);
+        try self.vx.queryTerminal(writer, .fromSeconds(1));
         try self.vx.setMouseMode(writer, true);
         if (self.vx.caps.color_scheme_updates)
             try self.vx.subscribeToColorSchemeUpdates(writer);
@@ -311,8 +316,8 @@ const Preview = struct {
             defer arena.deinit();
             const alloc = arena.allocator();
 
-            loop.pollEvent();
-            while (loop.tryEvent()) |event| {
+            try loop.pollEvent();
+            while (try loop.tryEvent()) |event| {
                 try self.update(event, alloc);
             }
             try self.draw(alloc);
@@ -366,7 +371,12 @@ const Preview = struct {
                 if (!shouldIncludeTheme(self.theme_filter, theme_config)) continue;
 
                 theme.rank = zf.rank(theme.theme, tokens.items, .{
-                    .to_lower = true,
+                    // NOTE: Changed from ".to_lower = true" (the option was
+                    // renamed). I think this is the correct analog for case
+                    // insensitive ranking (which is what I'm guessing
+                    // ".to_lower = true" implies, but this comment serves as a
+                    // hint if there's a regression.
+                    .case_sensitive = false,
                     .plain = true,
                 });
                 if (theme.rank != null) try self.filtered.append(self.allocator, i);
@@ -620,13 +630,21 @@ const Preview = struct {
                     self.down(1);
                 }
                 if (theme_list.hasMouse(mouse)) |_| {
+                    // NOTE: mouse co-ordinates can be negative (see
+                    // https://github.com/rockorager/libvaxis/pull/276).
+                    // Working around it in this case, but putting this here in
+                    // case there are issues.
                     if (mouse.button == .left and mouse.type == .release) {
-                        const selection = self.window + mouse.row;
+                        const selection: usize = selection: {
+                            var window: i32 = @min(self.window, std.math.maxInt(i32));
+                            window += mouse.row;
+                            break :selection @max(0, window);
+                        };
                         if (selection < self.filtered.items.len) {
                             self.current = selection;
                         }
                     }
-                    highlight = mouse.row;
+                    highlight = @max(0, mouse.row);
                 }
             }
         }
diff --git a/src/cli/new_window.zig b/src/cli/new_window.zig
index a89c4ffab..68a1c14e0 100644
--- a/src/cli/new_window.zig
+++ b/src/cli/new_window.zig
@@ -7,8 +7,12 @@ const args = @import("args.zig");
 const diagnostics = @import("diagnostics.zig");
 const lib = @import("../lib/main.zig");
 const homedir = @import("../os/homedir.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
+    /// We store an I/O implementation to make maintenance easier.
+    _io: std.Io,
+
     /// This is set by the CLI parser for deinit.
     _arena: ?ArenaAllocator = null,
 
@@ -26,8 +30,18 @@ pub const Options = struct {
     /// there is a "normal" config setting on the cli.
     _diagnostics: diagnostics.DiagnosticList = .{},
 
+    pub const ParseManuallyHookError = error{InvalidValue} ||
+        homedir.ExpandError ||
+        std.Io.Dir.RealPathFileAllocError ||
+        Allocator.Error;
+
     /// Manual parse hook, collect all of the arguments after `+new-window`.
-    pub fn parseManuallyHook(self: *Options, alloc: Allocator, arg: []const u8, iter: anytype) (error{InvalidValue} || homedir.ExpandError || std.fs.Dir.RealPathAllocError || Allocator.Error)!bool {
+    pub fn parseManuallyHook(
+        self: *Options,
+        alloc: Allocator,
+        arg: []const u8,
+        iter: anytype,
+    ) ParseManuallyHookError!bool {
         var e_seen: bool = std.mem.eql(u8, arg, "-e");
 
         // Include the argument that triggered the manual parse hook.
@@ -50,7 +64,12 @@ pub const Options = struct {
         return false;
     }
 
-    fn checkArg(self: *Options, alloc: Allocator, arg: []const u8) (error{InvalidValue} || homedir.ExpandError || std.fs.Dir.RealPathAllocError || Allocator.Error)!?[:0]const u8 {
+    const CheckArgError = error{InvalidValue} ||
+        homedir.ExpandError ||
+        std.Io.Dir.RealPathFileAllocError ||
+        Allocator.Error;
+
+    fn checkArg(self: *Options, alloc: Allocator, arg: []const u8) CheckArgError!?[:0]const u8 {
         if (lib.cutPrefix(u8, arg, "--class=")) |rest| {
             self.class = try alloc.dupeZ(u8, std.mem.trim(u8, rest, &std.ascii.whitespace));
             return null;
@@ -60,11 +79,15 @@ pub const Options = struct {
             const stripped = std.mem.trim(u8, rest, &std.ascii.whitespace);
             if (std.mem.eql(u8, stripped, "home")) return try alloc.dupeZ(u8, arg);
             if (std.mem.eql(u8, stripped, "inherit")) return try alloc.dupeZ(u8, arg);
-            const cwd: std.fs.Dir = std.fs.cwd();
+            const cwd: std.Io.Dir = .cwd();
             var expandhome_buf: [std.fs.max_path_bytes]u8 = undefined;
-            const expanded = try homedir.expandHome(stripped, &expandhome_buf);
+            const expanded = expanded: {
+                var environ_map = try global.environMap();
+                defer environ_map.deinit();
+                break :expanded try homedir.expandHome(&environ_map, stripped, &expandhome_buf);
+            };
             var realpath_buf: [std.fs.max_path_bytes]u8 = undefined;
-            const realpath = try cwd.realpath(expanded, &realpath_buf);
+            const realpath = realpath_buf[0..try cwd.realPathFile(self._io, expanded, &realpath_buf)];
             self._working_directory_seen = true;
             return try std.fmt.allocPrintSentinel(alloc, "--working-directory={s}", .{realpath}, 0);
         }
@@ -147,11 +170,11 @@ pub const Options = struct {
 ///
 /// Available since: 1.2.0
 pub fn run(alloc: Allocator) !u8 {
-    var iter = try args.argsIterator(alloc);
+    var iter = try args.argsIterator(alloc, global.args());
     defer iter.deinit();
 
     var buffer: [1024]u8 = undefined;
-    var stderr_writer = std.fs.File.stderr().writer(&buffer);
+    var stderr_writer = std.Io.File.stderr().writer(global.io(), &buffer);
     const stderr = &stderr_writer.interface;
 
     const result = runArgs(alloc, &iter, stderr);
@@ -164,7 +187,7 @@ fn runArgs(
     argsIter: anytype,
     stderr: *std.Io.Writer,
 ) !u8 {
-    var opts: Options = .{};
+    var opts: Options = .{ ._io = global.io() };
     defer opts.deinit();
 
     args.parse(Options, alloc_gpa, &opts, argsIter) catch |err| switch (err) {
@@ -195,11 +218,16 @@ fn runArgs(
 
     if (!opts._working_directory_seen) {
         const alloc = opts._arena.?.allocator();
-        const cwd: std.fs.Dir = std.fs.cwd();
+        const cwd: std.Io.Dir = .cwd();
         var buf: [std.fs.max_path_bytes]u8 = undefined;
-        const wd = try cwd.realpath(".", &buf);
+        const wd = buf[0..try cwd.realPathFile(global.io(), ".", &buf)];
         // This should be inserted at the beginning of the list, just in case `-e` was used.
-        try opts._arguments.insert(alloc, 0, try std.fmt.allocPrintSentinel(alloc, "--working-directory={s}", .{wd}, 0));
+        try opts._arguments.insert(alloc, 0, try std.fmt.allocPrintSentinel(
+            alloc,
+            "--working-directory={s}",
+            .{wd},
+            0,
+        ));
     }
 
     var arena = ArenaAllocator.init(alloc_gpa);
diff --git a/src/cli/show_config.zig b/src/cli/show_config.zig
index cd0ba89a7..60df2a773 100644
--- a/src/cli/show_config.zig
+++ b/src/cli/show_config.zig
@@ -5,6 +5,7 @@ const Action = @import("ghostty.zig").Action;
 const configpkg = @import("../config.zig");
 const Config = configpkg.Config;
 const Pager = @import("Pager.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// If true, do not load the user configuration, only load the defaults.
@@ -66,7 +67,7 @@ pub fn run(alloc: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc);
+        var iter = try args.argsIterator(alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc, &opts, &iter);
     }
@@ -81,7 +82,7 @@ pub fn run(alloc: Allocator) !u8 {
         .docs = opts.docs,
     };
 
-    var pager: Pager = if (!opts.@"no-pager") .init(alloc) else .{};
+    var pager: Pager = if (!opts.@"no-pager") .init() else .{};
     defer pager.deinit();
     var buffer: [4096]u8 = undefined;
     const writer = pager.writer(&buffer);
diff --git a/src/cli/show_face.zig b/src/cli/show_face.zig
index 9dee777b3..30bd550a0 100644
--- a/src/cli/show_face.zig
+++ b/src/cli/show_face.zig
@@ -7,6 +7,7 @@ const diagnostics = @import("diagnostics.zig");
 const font = @import("../font/main.zig");
 const configpkg = @import("../config.zig");
 const Config = configpkg.Config;
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// This is set by the CLI parser for deinit.
@@ -62,15 +63,15 @@ pub const Options = struct {
 ///     style. Valid options are `text` and `emoji`. If unset, the presentation
 ///     style of a codepoint will be inferred from the Unicode standard.
 pub fn run(alloc: Allocator) !u8 {
-    var iter = try args.argsIterator(alloc);
+    var iter = try args.argsIterator(alloc, global.args());
     defer iter.deinit();
 
     var stdout_buffer: [1024]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
+    var stdout_writer = std.Io.File.stdout().writer(global.io(), &stdout_buffer);
     const stdout = &stdout_writer.interface;
 
     var stderr_buffer: [1024]u8 = undefined;
-    var stderr_writer = std.fs.File.stdout().writer(&stderr_buffer);
+    var stderr_writer = std.Io.File.stdout().writer(global.io(), &stderr_buffer);
     const stderr = &stderr_writer.interface;
 
     const result = runArgs(
diff --git a/src/cli/ssh-cache/DiskCache.zig b/src/cli/ssh-cache/DiskCache.zig
index bb11e74fb..bda1d262f 100644
--- a/src/cli/ssh-cache/DiskCache.zig
+++ b/src/cli/ssh-cache/DiskCache.zig
@@ -10,6 +10,7 @@ const Allocator = std.mem.Allocator;
 const internal_os = @import("../../os/main.zig");
 const xdg = internal_os.xdg;
 const Entry = @import("Entry.zig");
+const global = @import("../../global.zig");
 
 // 512KB - sufficient for approximately 10k entries
 const MAX_CACHE_SIZE = 512 * 1024;
@@ -26,8 +27,11 @@ pub fn defaultPath(
     alloc: Allocator,
     program: []const u8,
 ) ![]const u8 {
+    var environ_map = try global.environMap();
+    defer environ_map.deinit();
     const state_dir: []const u8 = xdg.state(
         alloc,
+        &environ_map,
         .{ .subdir = program },
     ) catch |err| return switch (err) {
         error.OutOfMemory => error.OutOfMemory,
@@ -41,7 +45,7 @@ pub fn defaultPath(
 /// This removes the cache file from disk, effectively clearing all cached
 /// SSH terminfo entries.
 pub fn clear(self: DiskCache) !void {
-    std.fs.cwd().deleteFile(self.path) catch |err| switch (err) {
+    std.Io.Dir.cwd().deleteFile(global.io(), self.path) catch |err| switch (err) {
         error.FileNotFound => {},
         else => return err,
     };
@@ -59,36 +63,43 @@ pub fn add(
 
     // Create cache directory if needed
     if (std.fs.path.dirname(self.path)) |dir| {
-        std.fs.cwd().makePath(dir) catch |err| switch (err) {
+        std.Io.Dir.cwd().createDirPath(global.io(), dir) catch |err| switch (err) {
             error.PathAlreadyExists => {},
             else => return err,
         };
     }
 
     // Open or create cache file with secure permissions
-    const file = std.fs.createFileAbsolute(self.path, .{
+    const file = std.Io.Dir.createFileAbsolute(global.io(), self.path, .{
         .read = true,
         .truncate = false,
-        .mode = 0o600,
+        .permissions = if (builtin.os.tag != .windows and std.posix.mode_t != u0)
+            .fromMode(0o600)
+        else
+            .default_file,
     }) catch |err| switch (err) {
         error.PathAlreadyExists => blk: {
-            const existing_file = try std.fs.openFileAbsolute(
+            const existing_file = try std.Io.Dir.openFileAbsolute(
+                global.io(),
                 self.path,
                 .{ .mode = .read_write },
             );
-            errdefer existing_file.close();
+            errdefer existing_file.close(global.io());
             try fixupPermissions(existing_file);
             break :blk existing_file;
         },
         else => return err,
     };
-    defer file.close();
+    defer file.close(global.io());
 
     // Lock
     // Causes a compile failure in the Zig std library on Windows, see:
     // https://github.com/ziglang/zig/issues/18430
-    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheLocked;
-    defer if (comptime builtin.os.tag != .windows) file.unlock();
+    if (comptime builtin.os.tag != .windows) _ = file.tryLock(
+        global.io(),
+        .exclusive,
+    ) catch return error.CacheLocked;
+    defer if (comptime builtin.os.tag != .windows) file.unlock(global.io());
 
     var entries = try readEntries(alloc, file);
     defer deinitEntries(alloc, &entries);
@@ -125,21 +136,25 @@ pub fn remove(
     if (!isValidCacheKey(key)) return error.InvalidCacheKey;
 
     // Open our file
-    const file = std.fs.openFileAbsolute(
+    const file = std.Io.Dir.openFileAbsolute(
+        global.io(),
         self.path,
         .{ .mode = .read_write },
     ) catch |err| switch (err) {
         error.FileNotFound => return false,
         else => return err,
     };
-    defer file.close();
+    defer file.close(global.io());
     try fixupPermissions(file);
 
     // Lock
     // Causes a compile failure in the Zig std library on Windows, see:
     // https://github.com/ziglang/zig/issues/18430
-    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheLocked;
-    defer if (comptime builtin.os.tag != .windows) file.unlock();
+    if (comptime builtin.os.tag != .windows) _ = file.tryLock(
+        global.io(),
+        .exclusive,
+    ) catch return error.CacheLocked;
+    defer if (comptime builtin.os.tag != .windows) file.unlock(global.io());
 
     // Read existing entries
     var entries = try readEntries(alloc, file);
@@ -165,28 +180,32 @@ pub fn prune(
     alloc: Allocator,
     max_age_s: u64,
 ) !usize {
-    const file = std.fs.openFileAbsolute(
+    const file = std.Io.Dir.openFileAbsolute(
+        global.io(),
         self.path,
         .{ .mode = .read_write },
     ) catch |err| switch (err) {
         error.FileNotFound => return 0,
         else => return err,
     };
-    defer file.close();
+    defer file.close(global.io());
     try fixupPermissions(file);
 
     // Lock
     // Causes a compile failure in the Zig std library on Windows, see:
     // https://github.com/ziglang/zig/issues/18430
-    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheLocked;
-    defer if (comptime builtin.os.tag != .windows) file.unlock();
+    if (comptime builtin.os.tag != .windows) _ = file.tryLock(
+        global.io(),
+        .exclusive,
+    ) catch return error.CacheLocked;
+    defer if (comptime builtin.os.tag != .windows) file.unlock(global.io());
 
     // Read existing entries
     var entries = try readEntries(alloc, file);
     defer deinitEntries(alloc, &entries);
 
     // Drop expired entries from the map, then persist what remains.
-    const now = std.time.timestamp();
+    const now = std.Io.Timestamp.now(global.io(), .real).toSeconds();
     var expired: std.ArrayList([]const u8) = .empty;
     defer expired.deinit(alloc);
     var iter = entries.iterator();
@@ -215,14 +234,15 @@ pub fn contains(
     if (!isValidCacheKey(key)) return error.InvalidCacheKey;
 
     // Open our file
-    const file = std.fs.openFileAbsolute(
+    const file = std.Io.Dir.openFileAbsolute(
+        global.io(),
         self.path,
         .{},
     ) catch |err| switch (err) {
         error.FileNotFound => return false,
         else => return err,
     };
-    defer file.close();
+    defer file.close(global.io());
 
     // Read existing entries
     var entries = try readEntries(alloc, file);
@@ -231,15 +251,15 @@ pub fn contains(
     return entries.contains(key);
 }
 
-fn fixupPermissions(file: std.fs.File) !void {
+fn fixupPermissions(file: std.Io.File) !void {
     // Windows does not support chmod
     if (comptime builtin.os.tag == .windows) return;
 
     // Ensure file has correct permissions (readable/writable by
     // owner only)
-    const stat = try file.stat();
-    if (stat.mode & 0o777 != 0o600) {
-        try file.chmod(0o600);
+    const stat = try file.stat(global.io());
+    if (stat.permissions.toMode() & 0o777 != 0o600) {
+        try file.setPermissions(global.io(), .fromMode(0o600));
     }
 }
 
@@ -250,22 +270,27 @@ fn writeCacheFile(
     const cache_dir = std.fs.path.dirname(self.path) orelse return error.InvalidCachePath;
     const cache_basename = std.fs.path.basename(self.path);
 
-    var dir = try std.fs.cwd().openDir(cache_dir, .{});
-    defer dir.close();
+    var dir = try std.Io.Dir.cwd().openDir(global.io(), cache_dir, .{});
+    defer dir.close(global.io());
 
     var buf: [1024]u8 = undefined;
-    var atomic_file = try dir.atomicFile(cache_basename, .{
-        .mode = 0o600,
-        .write_buffer = &buf,
+    var atomic_file = try dir.createFileAtomic(global.io(), cache_basename, .{
+        .permissions = if (builtin.os.tag != .windows and std.posix.mode_t != u0)
+            .fromMode(0o600)
+        else
+            .default_file,
+        .replace = true,
     });
-    defer atomic_file.deinit();
+    defer atomic_file.deinit(global.io());
+    var file_writer = atomic_file.file.writer(global.io(), &buf);
 
     var iter = entries.iterator();
     while (iter.next()) |kv| {
-        try kv.value_ptr.format(&atomic_file.file_writer.interface);
+        try kv.value_ptr.format(&file_writer.interface);
     }
 
-    try atomic_file.finish();
+    try file_writer.flush();
+    try atomic_file.replace(global.io());
 }
 
 /// List all entries in the cache.
@@ -276,14 +301,15 @@ pub fn list(
     alloc: Allocator,
 ) !std.StringHashMap(Entry) {
     // Open our file
-    const file = std.fs.openFileAbsolute(
+    const file = std.Io.Dir.openFileAbsolute(
+        global.io(),
         self.path,
         .{},
     ) catch |err| switch (err) {
         error.FileNotFound => return .init(alloc),
         else => return err,
     };
-    defer file.close();
+    defer file.close(global.io());
     return readEntries(alloc, file);
 }
 
@@ -306,9 +332,9 @@ pub fn deinitEntries(
 
 fn readEntries(
     alloc: Allocator,
-    file: std.fs.File,
+    file: std.Io.File,
 ) !std.StringHashMap(Entry) {
-    var reader = file.reader(&.{});
+    var reader = file.reader(global.io(), &.{});
     const content = try reader.interface.allocRemaining(
         alloc,
         .limited(MAX_CACHE_SIZE),
@@ -392,7 +418,7 @@ fn isValidHost(host: []const u8) bool {
     // We also accept valid IP addresses. In practice, IPv4 addresses are also
     // considered valid hostnames due to their overlapping syntax, so we can
     // simplify this check to be IPv6-specific.
-    if (std.net.Address.parseIp6(host, 0)) |_| {
+    if (std.Io.net.IpAddress.parseIp6(host, 0)) |_| {
         return true;
     } else |_| {
         return false;
@@ -428,12 +454,12 @@ test "disk cache clear" {
     defer tmp.cleanup();
     var buf: [4096]u8 = undefined;
     {
-        var file = try tmp.dir.createFile("cache", .{});
-        defer file.close();
-        var file_writer = file.writer(&buf);
+        var file = try tmp.dir.createFile(testing.io, "cache", .{});
+        defer file.close(testing.io);
+        var file_writer = file.writer(testing.io, &buf);
         try file_writer.interface.writeAll("HELLO!");
     }
-    const path = try tmp.dir.realpathAlloc(alloc, "cache");
+    const path = try tmp.dir.realPathFileAlloc(testing.io, "cache", alloc);
     defer alloc.free(path);
 
     // Setup our cache
@@ -443,7 +469,7 @@ test "disk cache clear" {
     // Verify the file is gone
     try testing.expectError(
         error.FileNotFound,
-        tmp.dir.openFile("cache", .{}),
+        tmp.dir.openFile(testing.io, "cache", .{}),
     );
 }
 
@@ -456,21 +482,21 @@ test "disk cache operations" {
     defer tmp.cleanup();
     var buf: [4096]u8 = undefined;
     {
-        var file = try tmp.dir.createFile("cache", .{});
-        defer file.close();
-        var file_writer = file.writer(&buf);
+        var file = try tmp.dir.createFile(testing.io, "cache", .{});
+        defer file.close(testing.io);
+        var file_writer = file.writer(testing.io, &buf);
         const writer = &file_writer.interface;
         try writer.writeAll("HELLO!");
         try writer.flush();
     }
-    const path = try tmp.dir.realpathAlloc(alloc, "cache");
+    const path = try tmp.dir.realPathFileAlloc(testing.io, "cache", alloc);
     defer alloc.free(path);
 
     // Setup our cache. Adding the same key twice exercises both the new
     // and existing-entry paths.
     const cache: DiskCache = .{ .path = path };
-    try cache.add(alloc, "example.com", std.time.timestamp());
-    try cache.add(alloc, "example.com", std.time.timestamp());
+    try cache.add(alloc, "example.com", std.Io.Timestamp.now(testing.io, .real).toSeconds());
+    try cache.add(alloc, "example.com", std.Io.Timestamp.now(testing.io, .real).toSeconds());
     try testing.expect(try cache.contains(alloc, "example.com"));
 
     // List
@@ -482,7 +508,7 @@ test "disk cache operations" {
     try testing.expect(try cache.remove(alloc, "example.com"));
     try testing.expect(!try cache.remove(alloc, "example.com"));
     try testing.expect(!(try cache.contains(alloc, "example.com")));
-    try cache.add(alloc, "example.com", std.time.timestamp());
+    try cache.add(alloc, "example.com", std.Io.Timestamp.now(testing.io, .real).toSeconds());
 }
 
 test "disk cache cleans up temp files" {
@@ -492,19 +518,19 @@ test "disk cache cleans up temp files" {
     var tmp = testing.tmpDir(.{ .iterate = true });
     defer tmp.cleanup();
 
-    const tmp_path = try tmp.dir.realpathAlloc(alloc, ".");
+    const tmp_path = try tmp.dir.realPathFileAlloc(testing.io, ".", alloc);
     defer alloc.free(tmp_path);
     const cache_path = try std.fs.path.join(alloc, &.{ tmp_path, "cache" });
     defer alloc.free(cache_path);
 
     const cache: DiskCache = .{ .path = cache_path };
-    try cache.add(alloc, "example.com", std.time.timestamp());
-    try cache.add(alloc, "example.org", std.time.timestamp());
+    try cache.add(alloc, "example.com", std.Io.Timestamp.now(testing.io, .real).toSeconds());
+    try cache.add(alloc, "example.org", std.Io.Timestamp.now(testing.io, .real).toSeconds());
 
     // Verify only the cache file exists and no temp files left behind
     var count: usize = 0;
     var iter = tmp.dir.iterate();
-    while (try iter.next()) |entry| {
+    while (try iter.next(testing.io)) |entry| {
         count += 1;
         try testing.expectEqualStrings("cache", entry.name);
     }
@@ -514,10 +540,11 @@ test "disk cache cleans up temp files" {
 test "disk cache prune" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var tmp = testing.tmpDir(.{});
     defer tmp.cleanup();
-    const tmp_path = try tmp.dir.realpathAlloc(alloc, ".");
+    const tmp_path = try tmp.dir.realPathFileAlloc(io, ".", alloc);
     defer alloc.free(tmp_path);
     const cache_path = try std.fs.path.join(alloc, &.{ tmp_path, "cache" });
     defer alloc.free(cache_path);
@@ -527,7 +554,7 @@ test "disk cache prune" {
     // Back-date one entry an hour old and one 100 days old.
     const day = std.time.s_per_day;
     const hour = std.time.s_per_hour;
-    const now = std.time.timestamp();
+    const now = std.Io.Timestamp.now(testing.io, .real).toSeconds();
     try cache.add(alloc, "recent.com", now - hour);
     try cache.add(alloc, "old.com", now - 100 * day);
 
@@ -547,11 +574,12 @@ test "disk cache prune" {
 test "disk cache prune missing file" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var tmp = testing.tmpDir(.{});
     defer tmp.cleanup();
 
-    const tmp_path = try tmp.dir.realpathAlloc(alloc, ".");
+    const tmp_path = try tmp.dir.realPathFileAlloc(io, ".", alloc);
     defer alloc.free(tmp_path);
     const cache_path = try std.fs.path.join(alloc, &.{ tmp_path, "cache" });
     defer alloc.free(cache_path);
@@ -563,6 +591,7 @@ test "disk cache prune missing file" {
 test "disk cache reads duplicate keys" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var tmp = testing.tmpDir(.{});
     defer tmp.cleanup();
@@ -571,16 +600,16 @@ test "disk cache reads duplicate keys" {
     // key with the updated entry and ensure (via testing.allocator) that
     // we don't double-free or leak.
     {
-        var file = try tmp.dir.createFile("cache", .{});
-        defer file.close();
+        var file = try tmp.dir.createFile(io, "cache", .{});
+        defer file.close(io);
         var buf: [256]u8 = undefined;
-        var file_writer = file.writer(&buf);
+        var file_writer = file.writer(io, &buf);
         try file_writer.interface.writeAll(
             "example.com|100|xterm-ghostty\nexample.com|200|xterm-newer\n",
         );
         try file_writer.interface.flush();
     }
-    const path = try tmp.dir.realpathAlloc(alloc, "cache");
+    const path = try tmp.dir.realPathFileAlloc(io, "cache", alloc);
     defer alloc.free(path);
 
     const cache: DiskCache = .{ .path = path };
@@ -602,10 +631,10 @@ test "disk cache reads survive allocation failure" {
     // Exercise a populated cache containing a duplicate key to ensure
     // that we hit all of the possible allocation behaviors below.
     {
-        var file = try tmp.dir.createFile("cache", .{});
-        defer file.close();
+        var file = try tmp.dir.createFile(testing.io, "cache", .{});
+        defer file.close(testing.io);
         var buf: [256]u8 = undefined;
-        var file_writer = file.writer(&buf);
+        var file_writer = file.writer(testing.io, &buf);
         try file_writer.interface.writeAll(
             "a.com|100|xterm-ghostty\n" ++
                 "b.com|100|xterm-ghostty\n" ++
@@ -614,7 +643,7 @@ test "disk cache reads survive allocation failure" {
         );
         try file_writer.interface.flush();
     }
-    const path = try tmp.dir.realpathAlloc(testing.allocator, "cache");
+    const path = try tmp.dir.realPathFileAlloc(testing.io, "cache", testing.allocator);
     defer testing.allocator.free(path);
 
     const cache: DiskCache = .{ .path = path };
@@ -647,7 +676,7 @@ test "disk cache add survives allocation failure" {
 
     var tmp = testing.tmpDir(.{});
     defer tmp.cleanup();
-    const tmp_path = try tmp.dir.realpathAlloc(testing.allocator, ".");
+    const tmp_path = try tmp.dir.realPathFileAlloc(testing.io, ".", testing.allocator);
     defer testing.allocator.free(tmp_path);
     const path = try std.fs.path.join(testing.allocator, &.{ tmp_path, "cache" });
     defer testing.allocator.free(path);
@@ -660,7 +689,7 @@ test "disk cache add survives allocation failure" {
     // from a clean cache file.
     var fail_index: usize = 0;
     while (true) : (fail_index += 1) {
-        std.fs.cwd().deleteFile(path) catch {};
+        std.Io.Dir.cwd().deleteFile(testing.io, path) catch {};
         var failing = std.testing.FailingAllocator.init(
             testing.allocator,
             .{ .fail_index = fail_index },
diff --git a/src/cli/ssh.zig b/src/cli/ssh.zig
index 76bfb10ee..3b34109d1 100644
--- a/src/cli/ssh.zig
+++ b/src/cli/ssh.zig
@@ -1,4 +1,5 @@
 const std = @import("std");
+const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
 const cli_args = @import("args.zig");
@@ -7,6 +8,7 @@ const Action = @import("ghostty.zig").Action;
 const DiskCache = @import("ssh_cache.zig").DiskCache;
 const internal_os = @import("../os/main.zig");
 const ghostty_terminfo = @import("../terminfo/main.zig").ghostty;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.ssh);
 
@@ -181,14 +183,14 @@ pub fn run(alloc_gpa: Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try cli_args.argsIterator(alloc_gpa);
+        var iter = try cli_args.argsIterator(alloc_gpa, global.args());
         defer iter.deinit();
         try cli_args.parse(Options, alloc_gpa, &opts, &iter);
     }
 
     var stderr_buffer: [1024]u8 = undefined;
-    var stderr_file: std.fs.File = .stderr();
-    var stderr_writer = stderr_file.writer(&stderr_buffer);
+    var stderr_file: std.Io.File = .stderr();
+    var stderr_writer = stderr_file.writer(global.io(), &stderr_buffer);
     const stderr = &stderr_writer.interface;
 
     // Any diagnostic from the arg parser is an unknown flag or bad
@@ -294,7 +296,7 @@ fn runInner(
     });
     verbosePrint(opts, stderr, "exec: {f}", .{Joined{ .items = argv }});
 
-    const exit_code = childExec(alloc, argv) catch |err| {
+    const exit_code = childExec(argv) catch |err| {
         try stderr.print("Error: failed to run {s}: {}\n", .{ argv[0], err });
         return 1;
     };
@@ -302,7 +304,10 @@ fn runInner(
 
     // Attempt to cache (if needed) on a successful ssh execution.
     if (exit_code == 0) if (session.to_cache) |entry| {
-        if (entry.cache.add(alloc, entry.dest, std.time.timestamp())) |_| {
+        if (entry.cache.add(alloc, entry.dest, std.Io.Timestamp.now(
+            global.io(),
+            .real,
+        ).toSeconds())) |_| {
             verbosePrint(opts, stderr, "cache: wrote {s}", .{entry.dest});
         } else |err| {
             log.debug("cache add failed for '{s}': {}", .{ entry.dest, err });
@@ -370,7 +375,7 @@ const Joined = struct {
 
 fn checkExit(term: std.process.Child.Term, label: []const u8) error{ChildFailed}!void {
     switch (term) {
-        .Exited => |rc| if (rc != 0) {
+        .exited => |rc| if (rc != 0) {
             log.warn("{s} exited with non-zero status: {d}", .{ label, rc });
             return error.ChildFailed;
         },
@@ -393,10 +398,11 @@ fn resolveDestination(
         &.{ ssh, "-G" },
         args,
     }) catch return null;
-    const result = std.process.Child.run(.{
-        .allocator = alloc,
-        .argv = argv,
-    }) catch |err| {
+    const result = std.process.run(
+        alloc,
+        global.io(),
+        .{ .argv = argv },
+    ) catch |err| {
         log.warn("ssh -G spawn failed: {}", .{err});
         return null;
     };
@@ -491,23 +497,23 @@ fn installRemoteTerminfo(
     });
     verbosePrint(opts, stderr, "exec: {f}", .{Joined{ .items = argv }});
 
-    var child: std.process.Child = .init(argv, alloc);
-    child.stdin_behavior = .Pipe;
-    child.stdout_behavior = .Ignore;
-    child.stderr_behavior = if (opts.verbose) .Inherit else .Ignore;
-
-    child.spawn() catch |err| {
+    var child = std.process.spawn(global.io(), .{
+        .argv = argv,
+        .stdin = .pipe,
+        .stdout = .ignore,
+        .stderr = if (opts.verbose) .inherit else .ignore,
+    }) catch |err| {
         log.warn("terminfo install spawn failed: {}", .{err});
         return error.InstallFailed;
     };
 
     if (child.stdin) |stdin| {
-        stdin.writeAll(terminfo) catch {};
-        stdin.close();
+        stdin.writeStreamingAll(global.io(), terminfo) catch {};
+        stdin.close(global.io());
         child.stdin = null;
     }
 
-    const term = child.wait() catch |err| {
+    const term = child.wait(global.io()) catch |err| {
         log.warn("terminfo install wait failed: {}", .{err});
         return error.InstallFailed;
     };
@@ -515,23 +521,24 @@ fn installRemoteTerminfo(
 }
 
 /// Returns `128 + signum` for signal-killed children, matching shell convention.
-fn childExec(alloc: Allocator, argv: []const []const u8) !u8 {
-    var child: std.process.Child = .init(argv, alloc);
-    child.stdin_behavior = .Inherit;
-    child.stdout_behavior = .Inherit;
-    child.stderr_behavior = .Inherit;
+fn childExec(argv: []const []const u8) !u8 {
+    var child = try std.process.spawn(global.io(), .{
+        .argv = argv,
+        .stdin = .inherit,
+        .stdout = .inherit,
+        .stderr = .inherit,
+    });
 
-    try child.spawn();
-    const term = try child.wait();
+    const term = try child.wait(global.io());
     return switch (term) {
-        .Exited => |rc| rc,
-        .Signal => |sig| @as(u8, 128) + @as(u8, @intCast(@min(sig, 127))),
-        .Stopped, .Unknown => 1,
+        .exited => |rc| rc,
+        .signal => |sig| @as(u8, 128) + @as(u8, @intCast(@min(@intFromEnum(sig), 127))),
+        .stopped, .unknown => 1,
     };
 }
 
 fn parseTestArgs(alloc: Allocator, opts: *Options, line: []const u8) !void {
-    var iter = try std.process.ArgIteratorGeneral(.{}).init(alloc, line);
+    var iter = try std.process.Args.IteratorGeneral(.{}).init(alloc, line);
     defer iter.deinit();
     try cli_args.parse(Options, alloc, opts, &iter);
 }
diff --git a/src/cli/ssh_cache.zig b/src/cli/ssh_cache.zig
index 83031e8e7..b1b53657b 100644
--- a/src/cli/ssh_cache.zig
+++ b/src/cli/ssh_cache.zig
@@ -2,6 +2,7 @@ const std = @import("std");
 const fs = std.fs;
 const Allocator = std.mem.Allocator;
 const args = @import("args.zig");
+const global = @import("../global.zig");
 const Action = @import("ghostty.zig").Action;
 const Duration = @import("../config.zig").Config.Duration;
 pub const Entry = @import("ssh-cache/Entry.zig");
@@ -64,13 +65,13 @@ pub fn run(alloc_gpa: Allocator) !u8 {
     defer opts.deinit();
 
     var stdout_buffer: [1024]u8 = undefined;
-    var stdout_file: std.fs.File = .stdout();
-    var stdout_writer = stdout_file.writer(&stdout_buffer);
+    var stdout_file: std.Io.File = .stdout();
+    var stdout_writer = stdout_file.writer(global.io(), &stdout_buffer);
     const stdout = &stdout_writer.interface;
 
     var stderr_buffer: [1024]u8 = undefined;
-    var stderr_file: std.fs.File = .stderr();
-    var stderr_writer = stderr_file.writer(&stderr_buffer);
+    var stderr_file: std.Io.File = .stderr();
+    var stderr_writer = stderr_file.writer(global.io(), &stderr_buffer);
     const stderr = &stderr_writer.interface;
 
     // The cache is queried by a positional destination (`user@host` or a
@@ -81,7 +82,7 @@ pub fn run(alloc_gpa: Allocator) !u8 {
     var query: ?[]const u8 = null;
     var flags: std.ArrayList([]const u8) = .empty;
     {
-        var iter = try args.argsIterator(alloc_gpa);
+        var iter = try args.argsIterator(alloc_gpa, global.args());
         defer iter.deinit();
         while (iter.next()) |arg| {
             const is_host_flag = std.mem.startsWith(u8, arg, "--host=");
@@ -174,7 +175,11 @@ pub fn runInner(
     }
 
     if (opts.add) |dest| {
-        cache.add(alloc, dest, std.time.timestamp()) catch |err| switch (err) {
+        cache.add(
+            alloc,
+            dest,
+            std.Io.Timestamp.now(global.io(), .real).toSeconds(),
+        ) catch |err| switch (err) {
             error.InvalidCacheKey => {
                 try stderr.print(
                     "Error: Invalid destination '{s}' (expected hostname or user@hostname)\n",
@@ -295,7 +300,7 @@ fn listEntries(
         widest = @max(widest, entry.hostname.len);
     }
 
-    const now = std.time.timestamp();
+    const now = std.Io.Timestamp.now(global.io(), .real).toSeconds();
     for (items.items) |entry| {
         try writer.print("{s}", .{entry.hostname});
         try writer.splatByteAll(' ', widest - entry.hostname.len + 2);
diff --git a/src/cli/toggle_quick_terminal.zig b/src/cli/toggle_quick_terminal.zig
index 233700f77..6a1f043be 100644
--- a/src/cli/toggle_quick_terminal.zig
+++ b/src/cli/toggle_quick_terminal.zig
@@ -2,6 +2,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const Action = @import("../cli.zig").ghostty.Action;
 const apprt = @import("../apprt.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// If set, connect to a custom instance of Ghostty.
@@ -39,7 +40,7 @@ pub const Options = struct {
 /// Available since: 1.4.0
 pub fn run(alloc: Allocator) !u8 {
     var buf: [256]u8 = undefined;
-    var stderr_writer = std.fs.File.stderr().writer(&buf);
+    var stderr_writer = std.Io.File.stderr().writer(global.io(), &buf);
     const stderr = &stderr_writer.interface;
 
     if (apprt.App.performIpc(
diff --git a/src/cli/validate_config.zig b/src/cli/validate_config.zig
index 5586cf29f..3d5f28869 100644
--- a/src/cli/validate_config.zig
+++ b/src/cli/validate_config.zig
@@ -3,6 +3,7 @@ const Allocator = std.mem.Allocator;
 const args = @import("args.zig");
 const Action = @import("ghostty.zig").Action;
 const Config = @import("../config.zig").Config;
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// The path of the config file to validate. If this isn't specified,
@@ -34,13 +35,13 @@ pub fn run(alloc: std.mem.Allocator) !u8 {
     defer opts.deinit();
 
     {
-        var iter = try args.argsIterator(alloc);
+        var iter = try args.argsIterator(alloc, global.args());
         defer iter.deinit();
         try args.parse(Options, alloc, &opts, &iter);
     }
 
     var buffer: [1024]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(global.io(), &buffer);
     const stdout = &stdout_writer.interface;
     const result = runInner(alloc, opts, stdout);
     try stdout_writer.end();
@@ -58,7 +59,11 @@ fn runInner(
     // If a config path is passed, validate it, otherwise validate default configs
     if (opts.@"config-file") |config_path| {
         var buf: [std.fs.max_path_bytes]u8 = undefined;
-        const abs_path = try std.fs.cwd().realpath(config_path, &buf);
+        const abs_path = buf[0..try std.Io.Dir.cwd().realPathFile(
+            global.io(),
+            config_path,
+            &buf,
+        )];
         try cfg.loadFile(alloc, abs_path);
         try cfg.loadRecursiveFiles(alloc);
     } else {
diff --git a/src/cli/version.zig b/src/cli/version.zig
index cf8e66fa6..ff203624b 100644
--- a/src/cli/version.zig
+++ b/src/cli/version.zig
@@ -6,6 +6,7 @@ const build_config = @import("../build_config.zig");
 const internal_os = @import("../os/main.zig");
 const xev = @import("../global.zig").xev;
 const renderer = @import("../renderer.zig");
+const global = @import("../global.zig");
 
 const gtk_version = @import("../apprt/gtk/gtk_version.zig");
 const adw_version = @import("../apprt/gtk/adw_version.zig");
@@ -16,11 +17,14 @@ pub const Options = struct {};
 /// either `+version` or `--version`.
 pub fn run(alloc: Allocator) !u8 {
     var buffer: [1024]u8 = undefined;
-    const stdout_file: std.fs.File = .stdout();
-    var stdout_writer = stdout_file.writer(&buffer);
+    const stdout_file: std.Io.File = .stdout();
+    var stdout_writer = stdout_file.writer(global.io(), &buffer);
+
+    var environ_map = try global.environMap();
+    defer environ_map.deinit();
 
     const stdout = &stdout_writer.interface;
-    const tty = stdout_file.isTty();
+    const tty = try stdout_file.isTty(global.io());
 
     if (tty) if (build_config.version.build) |commit_hash| {
         try stdout.print(
@@ -48,7 +52,7 @@ pub fn run(alloc: Allocator) !u8 {
             defer if (kernel_info) |k| alloc.free(k);
             try stdout.print("  - kernel version: {s}\n", .{kernel_info orelse "Kernel information unavailable"});
         }
-        try stdout.print("  - desktop env   : {t}\n", .{internal_os.desktopEnvironment()});
+        try stdout.print("  - desktop env   : {t}\n", .{internal_os.desktopEnvironment(&environ_map)});
         try stdout.print("  - GTK version   :\n", .{});
         try stdout.print("    build         : {f}\n", .{gtk_version.comptime_version});
         try stdout.print("    runtime       : {f}\n", .{gtk_version.getRuntimeVersion()});
diff --git a/src/config/CApi.zig b/src/config/CApi.zig
index 7d3366c93..f69f48ea4 100644
--- a/src/config/CApi.zig
+++ b/src/config/CApi.zig
@@ -1,7 +1,7 @@
 const builtin = @import("builtin");
 const std = @import("std");
 const inputpkg = @import("../input.zig");
-const state = &@import("../global.zig").state;
+const global = @import("../global.zig");
 const String = @import("../main_c.zig").String;
 
 const Config = @import("Config.zig");
@@ -13,14 +13,14 @@ const log = std.log.scoped(.config);
 
 /// Create a new configuration filled with the initial default values.
 export fn ghostty_config_new() ?*Config {
-    const result = state.alloc.create(Config) catch |err| {
+    const result = global.alloc().create(Config) catch |err| {
         log.err("error allocating config err={}", .{err});
         return null;
     };
 
-    result.* = Config.default(state.alloc) catch |err| {
+    result.* = Config.default(global.alloc()) catch |err| {
         log.err("error creating config err={}", .{err});
-        state.alloc.destroy(result);
+        global.alloc().destroy(result);
         return null;
     };
 
@@ -30,20 +30,20 @@ export fn ghostty_config_new() ?*Config {
 export fn ghostty_config_free(ptr: ?*Config) void {
     if (ptr) |v| {
         v.deinit();
-        state.alloc.destroy(v);
+        global.alloc().destroy(v);
     }
 }
 
 /// Deep clone the configuration.
 export fn ghostty_config_clone(self: *Config) ?*Config {
-    const result = state.alloc.create(Config) catch |err| {
+    const result = global.alloc().create(Config) catch |err| {
         log.err("error allocating config err={}", .{err});
         return null;
     };
 
-    result.* = self.clone(state.alloc) catch |err| {
+    result.* = self.clone(global.alloc()) catch |err| {
         log.err("error cloning config err={}", .{err});
-        state.alloc.destroy(result);
+        global.alloc().destroy(result);
         return null;
     };
 
@@ -52,7 +52,7 @@ export fn ghostty_config_clone(self: *Config) ?*Config {
 
 /// Load the configuration from the CLI args.
 export fn ghostty_config_load_cli_args(self: *Config) void {
-    self.loadCliArgs(state.alloc) catch |err| {
+    self.loadCliArgs(global.alloc()) catch |err| {
         log.err("error loading config err={}", .{err});
     };
 }
@@ -61,7 +61,7 @@ export fn ghostty_config_load_cli_args(self: *Config) void {
 /// is usually done first. The default file locations are locations
 /// such as the home directory.
 export fn ghostty_config_load_default_files(self: *Config) void {
-    self.loadDefaultFiles(state.alloc) catch |err| {
+    self.loadDefaultFiles(global.alloc()) catch |err| {
         log.err("error loading config err={}", .{err});
     };
 }
@@ -70,7 +70,7 @@ export fn ghostty_config_load_default_files(self: *Config) void {
 /// The path must be null-terminated.
 export fn ghostty_config_load_file(self: *Config, path: [*:0]const u8) void {
     const path_slice = std.mem.span(path);
-    self.loadFile(state.alloc, path_slice) catch |err| {
+    self.loadFile(global.alloc(), path_slice) catch |err| {
         log.err("error loading config from file path={s} err={}", .{ path_slice, err });
     };
 }
@@ -79,7 +79,7 @@ export fn ghostty_config_load_file(self: *Config, path: [*:0]const u8) void {
 /// file locations in the previously loaded configuration. This will
 /// recursively continue to load up to a built-in limit.
 export fn ghostty_config_load_recursive_files(self: *Config) void {
-    self.loadRecursiveFiles(state.alloc) catch |err| {
+    self.loadRecursiveFiles(global.alloc()) catch |err| {
         log.err("error loading config err={}", .{err});
     };
 }
@@ -133,7 +133,7 @@ export fn ghostty_config_get_diagnostic(self: *Config, idx: u32) Diagnostic {
 }
 
 export fn ghostty_config_open_path() String {
-    const path = edit.openPath(state.alloc) catch |err| {
+    const path = edit.openPath(global.alloc()) catch |err| {
         log.err("error opening config in editor err={}", .{err});
         return .empty;
     };
diff --git a/src/config/Config.zig b/src/config/Config.zig
index 4db4a5cf5..90ccfc319 100644
--- a/src/config/Config.zig
+++ b/src/config/Config.zig
@@ -16,7 +16,7 @@ const build_config = @import("../build_config.zig");
 const assert = @import("../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
-const global_state = &@import("../global.zig").state;
+const global = @import("../global.zig");
 const deepEqual = @import("../datastruct/comparison.zig").deepEqual;
 const fontpkg = @import("../font/main.zig");
 const inputpkg = @import("../input.zig");
@@ -3848,7 +3848,7 @@ _conditional_set: std.EnumSet(conditional.Key) = .{},
 /// The steps we can use to reload the configuration after it has been loaded
 /// without reopening the files. This is used in very specific cases such
 /// as loadTheme which has more details on why.
-_replay_steps: std.ArrayListUnmanaged(Replay.Step) = .{},
+_replay_steps: std.ArrayList(Replay.Step) = .empty,
 
 /// Set to true if Ghostty was executed as xdg-terminal-exec on Linux.
 @"_xdg-terminal-exec": bool = false,
@@ -3922,7 +3922,7 @@ pub fn loadIter(
 /// `path` must be resolved and absolute.
 pub fn loadFile(self: *Config, alloc: Allocator, path: []const u8) !void {
     assert(std.fs.path.isAbsolute(path));
-    var file = file_load.open(path) catch |err| switch (err) {
+    var file = file_load.open(global.io(), path) catch |err| switch (err) {
         error.NotAFile => {
             log.warn(
                 "config-file {s}: not reading because it is not a file",
@@ -3933,16 +3933,16 @@ pub fn loadFile(self: *Config, alloc: Allocator, path: []const u8) !void {
 
         else => return err,
     };
-    defer file.close();
+    defer file.close(global.io());
 
     try self.loadFsFile(alloc, &file, path);
 }
 
 /// Load config from the given File.
-fn loadFsFile(self: *Config, alloc: Allocator, file: *std.fs.File, path: []const u8) !void {
+fn loadFsFile(self: *Config, alloc: Allocator, file: *std.Io.File, path: []const u8) !void {
     std.log.info("reading configuration file path={s}", .{path});
     var buf: [2048]u8 = undefined;
-    var file_reader = file.reader(&buf);
+    var file_reader = file.reader(global.io(), &buf);
     const reader = &file_reader.interface;
     try self.loadReader(alloc, reader, path);
 }
@@ -4035,12 +4035,12 @@ pub fn loadOptionalFile(
 fn writeConfigTemplate(path: []const u8) !void {
     log.info("creating template config file: path={s}", .{path});
     if (std.fs.path.dirname(path)) |dir_path| {
-        try std.fs.cwd().makePath(dir_path);
+        try std.Io.Dir.cwd().createDirPath(global.io(), dir_path);
     }
-    const file = try std.fs.createFileAbsolute(path, .{});
-    defer file.close();
+    const file = try std.Io.Dir.createFileAbsolute(global.io(), path, .{});
+    defer file.close(global.io());
     var buf: [4096]u8 = undefined;
-    var file_writer = file.writer(&buf);
+    var file_writer = file.writer(global.io(), &buf);
     const writer = &file_writer.interface;
     try writer.print(
         @embedFile("./config-template"),
@@ -4134,7 +4134,7 @@ pub fn loadCliArgs(self: *Config, alloc_gpa: Allocator) !void {
         .windows => {},
 
         // Fast-path if we are Linux/BSD and have no args.
-        .linux, .freebsd => if (std.os.argv.len <= 1) return,
+        .linux, .freebsd => if (global.args().vector.len <= 1) return,
 
         // Everything else we have to at least try because it may
         // not use std.os.argv.
@@ -4153,7 +4153,7 @@ pub fn loadCliArgs(self: *Config, alloc_gpa: Allocator) !void {
     //
     // See: https://github.com/Vladimir-csp/xdg-terminal-exec
     if ((comptime builtin.os.tag == .linux) or (comptime builtin.os.tag == .freebsd)) {
-        if (internal_os.xdg.parseTerminalExec(std.os.argv)) |args| {
+        if (internal_os.xdg.parseTerminalExec(global.args().vector)) |args| {
             const arena_alloc = self._arena.?.allocator();
 
             // First, we add an artificial "-e" so that if we
@@ -4203,7 +4203,7 @@ pub fn loadCliArgs(self: *Config, alloc_gpa: Allocator) !void {
     }
 
     // Initialize our CLI iterator.
-    var iter = try cli.args.argsIterator(alloc_gpa);
+    var iter = try cli.args.argsIterator(alloc_gpa, global.args());
     defer iter.deinit();
     try self.loadIter(alloc_gpa, &iter);
 
@@ -4229,7 +4229,11 @@ pub fn loadCliArgs(self: *Config, alloc_gpa: Allocator) !void {
     // Any paths referenced from the CLI are relative to the current working
     // directory.
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    try self.expandPaths(try std.fs.cwd().realpath(".", &buf));
+    try self.expandPaths(buf[0..try std.Io.Dir.cwd().realPathFile(
+        global.io(),
+        ".",
+        &buf,
+    )]);
 }
 
 /// Load and parse the config files that were added in the "config-file" key.
@@ -4292,7 +4296,7 @@ pub fn loadRecursiveFiles(self: *Config, alloc_gpa: Allocator) !void {
             continue;
         }
 
-        var file = std.fs.openFileAbsolute(path, .{}) catch |err| {
+        var file = std.Io.Dir.openFileAbsolute(global.io(), path, .{}) catch |err| {
             if (err != error.FileNotFound or !optional) {
                 const diag: cli.Diagnostic = .{
                     .message = try std.fmt.allocPrintSentinel(
@@ -4308,9 +4312,9 @@ pub fn loadRecursiveFiles(self: *Config, alloc_gpa: Allocator) !void {
             }
             continue;
         };
-        defer file.close();
+        defer file.close(global.io());
 
-        const stat = try file.stat();
+        const stat = try file.stat(global.io());
         switch (stat.kind) {
             .file => {},
             else => |kind| {
@@ -4455,7 +4459,7 @@ fn loadTheme(self: *Config, theme: Theme) !void {
     )) orelse return;
     const path = themefile.path;
     const file = themefile.file;
-    defer file.close();
+    defer file.close(global.io());
 
     // From this point onwards, we load the theme and do a bit of a dance
     // to achieve two separate goals:
@@ -4477,7 +4481,7 @@ fn loadTheme(self: *Config, theme: Theme) !void {
 
     // Load our theme
     var buf: [2048]u8 = undefined;
-    var file_reader = file.reader(&buf);
+    var file_reader = file.reader(global.io(), &buf);
     const reader = &file_reader.interface;
     var iter: cli.args.LineIterator = .{ .r = reader, .filepath = path };
     try new_config.loadIter(alloc_gpa, &iter);
@@ -4614,15 +4618,19 @@ pub fn finalize(self: *Config) !void {
                 // read from SHELL if we're in a probable CLI environment.
                 if (!probable_cli) break :shell_env;
 
-                if (std.process.getEnvVarOwned(alloc, "SHELL")) |value| {
-                    log.info("default shell source=env value={s}", .{value});
+                const value = global.environ().getAlloc(alloc, "SHELL") catch |err| switch (err) {
+                    error.EnvironmentVariableMissing => break :shell_env,
+                    else => return err,
+                };
+                defer alloc.free(value);
 
-                    const copy = try alloc.dupeZ(u8, value);
-                    self.command = .{ .shell = copy };
+                log.info("default shell source=env value={s}", .{value});
 
-                    // If we don't need the working directory, then we can exit now.
-                    if (wd != .home) break :command;
-                } else |_| {}
+                const copy = try alloc.dupeZ(u8, value);
+                self.command = .{ .shell = copy };
+
+                // If we don't need the working directory, then we can exit now.
+                if (wd != .home) break :command;
             }
 
             switch (builtin.os.tag) {
@@ -4633,8 +4641,10 @@ pub fn finalize(self: *Config) !void {
                     }
 
                     if (wd == .home) {
+                        var environ_map = try global.environMap();
+                        defer environ_map.deinit();
                         var buf: [std.fs.max_path_bytes]u8 = undefined;
-                        if (try internal_os.home(&buf)) |home| {
+                        if (try internal_os.home(&environ_map, &buf)) |home| {
                             wd = .{ .path = try alloc.dupe(u8, home) };
                         } else {
                             wd = .inherit;
@@ -5123,14 +5133,17 @@ fn probableCliEnvironment() bool {
         else => {},
     }
 
-    // If we have TERM_PROGRAM set to a non-empty value, we assume
-    // a graphical terminal environment.
-    if (std.posix.getenv("TERM_PROGRAM")) |v| {
-        if (v.len > 0) return true;
-    }
+    // If we have TERM_PROGRAM set to a non-empty value, we assume a graphical
+    // terminal environment.
+    //
+    // TODO: This is not available on WASI without libc due to the memory
+    // allocation requirement. This restricts this function to said platforms.
+    // To be fair, the legacy getenv path had more restrictive issues (no WASI
+    // period, or Windows for that matter).
+    if (global.environ().containsUnemptyConstant("TERM_PROGRAM")) return true;
 
     // CLI arguments makes things probable
-    if (std.os.argv.len > 1) return true;
+    if (global.args().vector.len > 1) return true;
 
     // Unlikely CLI environment
     return false;
@@ -5358,7 +5371,11 @@ pub const WorkingDirectory = union(enum) {
         if (!std.mem.startsWith(u8, path, "~/")) return;
 
         var buf: [std.fs.max_path_bytes]u8 = undefined;
-        const expanded = internal_os.expandHome(path, &buf) catch |err| {
+        const expanded = expanded: {
+            var environ_map = global.environMap() catch |err| break :expanded err;
+            defer environ_map.deinit();
+            break :expanded internal_os.expandHome(&environ_map, path, &buf);
+        } catch |err| {
             log.warn(
                 "error expanding home directory for working-directory path={s}: {}",
                 .{ path, err },
@@ -5417,6 +5434,8 @@ pub const WorkingDirectory = union(enum) {
         var arena = ArenaAllocator.init(testing.allocator);
         defer arena.deinit();
         const alloc = arena.allocator();
+        var environ_map = try testing.environ.createMap(testing.allocator);
+        defer environ_map.deinit();
 
         {
             var wd: Self = .{ .path = "~/projects/ghostty" };
@@ -5424,6 +5443,7 @@ pub const WorkingDirectory = union(enum) {
 
             var buf: [std.fs.max_path_bytes]u8 = undefined;
             const expected = internal_os.expandHome(
+                &environ_map,
                 "~/projects/ghostty",
                 &buf,
             ) catch "~/projects/ghostty";
@@ -5658,8 +5678,8 @@ pub const BoldColor = union(enum) {
 pub const ColorList = struct {
     const Self = @This();
 
-    colors: std.ArrayListUnmanaged(Color) = .{},
-    colors_c: std.ArrayListUnmanaged(Color.C) = .{},
+    colors: std.ArrayList(Color) = .empty,
+    colors_c: std.ArrayList(Color.C) = .empty,
 
     /// ghostty_config_color_list_s
     pub const C = extern struct {
@@ -5972,7 +5992,7 @@ pub const RepeatableString = struct {
     const Self = @This();
 
     // Allocator for the list is the arena for the parent config.
-    list: std.ArrayListUnmanaged([:0]const u8) = .{},
+    list: std.ArrayList([:0]const u8) = .empty,
 
     // If true, then the next value will clear the list and start over
     // rather than append. This is a bit of a hack but is here to make
@@ -6262,7 +6282,7 @@ pub const RepeatableFontVariation = struct {
     const Self = @This();
 
     // Allocator for the list is the arena for the parent config.
-    list: std.ArrayListUnmanaged(fontpkg.face.Variation) = .{},
+    list: std.ArrayList(fontpkg.face.Variation) = .empty,
 
     pub fn parseCLI(self: *Self, alloc: Allocator, input_: ?[]const u8) !void {
         const input = input_ orelse return error.ValueRequired;
@@ -8545,7 +8565,7 @@ pub const FontShapingBreak = packed struct {
 pub const RepeatableLink = struct {
     const Self = @This();
 
-    links: std.ArrayListUnmanaged(inputpkg.Link) = .{},
+    links: std.ArrayList(inputpkg.Link) = .empty,
 
     pub fn parseCLI(self: *Self, alloc: Allocator, input_: ?[]const u8) !void {
         _ = self;
@@ -10412,23 +10432,23 @@ test "clone can then change conditional state" {
     defer td.deinit();
     var buf: [4096]u8 = undefined;
     {
-        var file = try td.dir.createFile("theme_light", .{});
-        defer file.close();
-        var writer = file.writer(&buf);
+        var file = try td.dir.createFile(testing.io, "theme_light", .{});
+        defer file.close(testing.io);
+        var writer = file.writer(testing.io, &buf);
         try writer.interface.writeAll(@embedFile("testdata/theme_light"));
         try writer.end();
     }
     {
-        var file = try td.dir.createFile("theme_dark", .{});
-        defer file.close();
-        var writer = file.writer(&buf);
+        var file = try td.dir.createFile(testing.io, "theme_dark", .{});
+        defer file.close(testing.io);
+        var writer = file.writer(testing.io, &buf);
         try writer.interface.writeAll(@embedFile("testdata/theme_dark"));
         try writer.end();
     }
     var light_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const light = try td.dir.realpath("theme_light", &light_buf);
+    const light = light_buf[0..try td.dir.realPathFile(testing.io, "theme_light", &light_buf)];
     var dark_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const dark = try td.dir.realpath("theme_dark", &dark_buf);
+    const dark = dark_buf[0..try td.dir.realPathFile(testing.io, "theme_dark", &dark_buf)];
 
     var cfg_light = try Config.default(alloc);
     defer cfg_light.deinit();
@@ -10490,6 +10510,8 @@ test "clone preserves conditional set" {
 test "working-directory expands tilde" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    var environ_map = try testing.environ.createMap(testing.allocator);
+    defer environ_map.deinit();
 
     var cfg = try Config.default(alloc);
     defer cfg.deinit();
@@ -10501,6 +10523,7 @@ test "working-directory expands tilde" {
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
     const expected = internal_os.expandHome(
+        &environ_map,
         "~/projects/ghostty",
         &buf,
     ) catch "~/projects/ghostty";
@@ -10571,14 +10594,14 @@ test "theme loading" {
     defer td.deinit();
     var buf: [4096]u8 = undefined;
     {
-        var file = try td.dir.createFile("theme", .{});
-        defer file.close();
-        var writer = file.writer(&buf);
+        var file = try td.dir.createFile(testing.io, "theme", .{});
+        defer file.close(testing.io);
+        var writer = file.writer(testing.io, &buf);
         try writer.interface.writeAll(@embedFile("testdata/theme_simple"));
         try writer.end();
     }
     var path_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try td.dir.realpath("theme", &path_buf);
+    const path = path_buf[0..try td.dir.realPathFile(testing.io, "theme", &path_buf)];
 
     var cfg = try Config.default(alloc);
     defer cfg.deinit();
@@ -10610,14 +10633,14 @@ test "theme loading preserves conditional state" {
     defer td.deinit();
     var buf: [4096]u8 = undefined;
     {
-        var file = try td.dir.createFile("theme", .{});
-        defer file.close();
-        var writer = file.writer(&buf);
+        var file = try td.dir.createFile(testing.io, "theme", .{});
+        defer file.close(testing.io);
+        var writer = file.writer(testing.io, &buf);
         try writer.interface.writeAll(@embedFile("testdata/theme_simple"));
         try writer.end();
     }
     var path_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try td.dir.realpath("theme", &path_buf);
+    const path = path_buf[0..try td.dir.realPathFile(testing.io, "theme", &path_buf)];
 
     var cfg = try Config.default(alloc);
     defer cfg.deinit();
@@ -10643,14 +10666,14 @@ test "theme priority is lower than config" {
     defer td.deinit();
     var buf: [4096]u8 = undefined;
     {
-        var file = try td.dir.createFile("theme", .{});
-        defer file.close();
-        var writer = file.writer(&buf);
+        var file = try td.dir.createFile(testing.io, "theme", .{});
+        defer file.close(testing.io);
+        var writer = file.writer(testing.io, &buf);
         try writer.interface.writeAll(@embedFile("testdata/theme_simple"));
         try writer.end();
     }
     var path_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try td.dir.realpath("theme", &path_buf);
+    const path = path_buf[0..try td.dir.realPathFile(testing.io, "theme", &path_buf)];
 
     var cfg = try Config.default(alloc);
     defer cfg.deinit();
@@ -10680,23 +10703,23 @@ test "theme loading correct light/dark" {
     defer td.deinit();
     var buf: [4096]u8 = undefined;
     {
-        var file = try td.dir.createFile("theme_light", .{});
-        defer file.close();
-        var writer = file.writer(&buf);
+        var file = try td.dir.createFile(testing.io, "theme_light", .{});
+        defer file.close(testing.io);
+        var writer = file.writer(testing.io, &buf);
         try writer.interface.writeAll(@embedFile("testdata/theme_light"));
         try writer.end();
     }
     {
-        var file = try td.dir.createFile("theme_dark", .{});
-        defer file.close();
-        var writer = file.writer(&buf);
+        var file = try td.dir.createFile(testing.io, "theme_dark", .{});
+        defer file.close(testing.io);
+        var writer = file.writer(testing.io, &buf);
         try writer.interface.writeAll(@embedFile("testdata/theme_dark"));
         try writer.end();
     }
     var light_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const light = try td.dir.realpath("theme_light", &light_buf);
+    const light = light_buf[0..try td.dir.realPathFile(testing.io, "theme_light", &light_buf)];
     var dark_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const dark = try td.dir.realpath("theme_dark", &dark_buf);
+    const dark = dark_buf[0..try td.dir.realPathFile(testing.io, "theme_dark", &dark_buf)];
 
     // Light
     {
diff --git a/src/config/c_get.zig b/src/config/c_get.zig
index dcfdc6716..9bcb8d982 100644
--- a/src/config/c_get.zig
+++ b/src/config/c_get.zig
@@ -84,7 +84,7 @@ fn getValue(ptr_raw: *anyopaque, value: anytype) bool {
                 ptr.* = @intCast(@as(Backing, @bitCast(value)));
             },
 
-            .@"union" => |_| {
+            .@"union" => {
                 if (@hasDecl(T, "cval")) {
                     const PtrT = @typeInfo(@TypeOf(T.cval)).@"fn".return_type.?;
                     const ptr: *PtrT = @ptrCast(@alignCast(ptr_raw));
diff --git a/src/config/command.zig b/src/config/command.zig
index 7cd70acb3..b48bee189 100644
--- a/src/config/command.zig
+++ b/src/config/command.zig
@@ -123,7 +123,7 @@ pub const Command = union(enum) {
 
     /// Iterates over each argument in the command.
     pub const ArgIterator = union(enum) {
-        shell: std.process.ArgIteratorGeneral(.{}),
+        shell: std.process.Args.IteratorGeneral(.{}),
         direct: struct {
             i: usize = 0,
             args: []const [:0]const u8,
diff --git a/src/config/conditional.zig b/src/config/conditional.zig
index fdc285a22..e1a787927 100644
--- a/src/config/conditional.zig
+++ b/src/config/conditional.zig
@@ -39,18 +39,16 @@ pub const State = struct {
 /// An enum of the available conditional configuration keys.
 pub const Key = key: {
     const stateInfo = @typeInfo(State).@"struct";
-    var fields: [stateInfo.fields.len]std.builtin.Type.EnumField = undefined;
-    for (stateInfo.fields, 0..) |field, i| fields[i] = .{
-        .name = field.name,
-        .value = i,
-    };
+    const TagInt = std.math.IntFittingRange(0, stateInfo.fields.len - 1);
+    var names: [stateInfo.fields.len][]const u8 = undefined;
+    var values: [stateInfo.fields.len]TagInt = undefined;
 
-    break :key @Type(.{ .@"enum" = .{
-        .tag_type = std.math.IntFittingRange(0, fields.len - 1),
-        .fields = &fields,
-        .decls = &.{},
-        .is_exhaustive = true,
-    } });
+    for (stateInfo.fields, &names, &values, 0..) |field, *name, *v, i| {
+        name.* = field.name;
+        v.* = @intCast(i);
+    }
+
+    break :key @Enum(TagInt, .exhaustive, &names, &values);
 };
 
 /// A single conditional that can be true or false.
diff --git a/src/config/edit.zig b/src/config/edit.zig
index 8cedc47a5..24097498e 100644
--- a/src/config/edit.zig
+++ b/src/config/edit.zig
@@ -4,6 +4,7 @@ const assert = @import("../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
 const file_load = @import("file_load.zig");
+const global = @import("../global.zig");
 
 /// The path to the configuration that should be opened for editing.
 ///
@@ -28,11 +29,12 @@ pub fn openPath(alloc_gpa: Allocator) ![:0]const u8 {
 
     // Create config directory recursively.
     if (std.fs.path.dirname(config_path)) |config_dir| {
-        try std.fs.cwd().makePath(config_dir);
+        try std.Io.Dir.cwd().createDirPath(global.io(), config_dir);
     }
 
     // Try to create file and go on if it already exists
-    _ = std.fs.createFileAbsolute(
+    _ = std.Io.Dir.createFileAbsolute(
+        global.io(),
         config_path,
         .{ .exclusive = true },
     ) catch |err| {
@@ -58,7 +60,7 @@ fn configPath(alloc_arena: Allocator) ![]const u8 {
     // exists.
     var exists: ?[]const u8 = null;
     for (paths) |path| {
-        const f = std.fs.openFileAbsolute(path, .{}) catch |err| {
+        const f = std.Io.Dir.openFileAbsolute(global.io(), path, .{}) catch |err| {
             switch (err) {
                 // File doesn't exist, continue.
                 error.BadPathName, error.FileNotFound => continue,
@@ -67,10 +69,10 @@ fn configPath(alloc_arena: Allocator) ![]const u8 {
                 else => return err,
             }
         };
-        defer f.close();
+        defer f.close(global.io());
 
         // We expect stat to succeed because we just opened the file.
-        const stat = try f.stat();
+        const stat = try f.stat(global.io());
 
         // If the file is non-empty, return it.
         if (stat.size > 0) return path;
diff --git a/src/config/file_load.zig b/src/config/file_load.zig
index 7885de32a..ac5ddff6a 100644
--- a/src/config/file_load.zig
+++ b/src/config/file_load.zig
@@ -3,14 +3,18 @@ const builtin = @import("builtin");
 const assert = @import("../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const internal_os = @import("../os/main.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.config);
 
 /// Default path for the XDG home configuration file. Returned value
 /// must be freed by the caller.
 pub fn defaultXdgPath(alloc: Allocator) ![]const u8 {
+    var environ_map = try global.environMap();
+    defer environ_map.deinit();
     return try internal_os.xdg.config(
         alloc,
+        &environ_map,
         .{ .subdir = "ghostty/config.ghostty" },
     );
 }
@@ -18,8 +22,11 @@ pub fn defaultXdgPath(alloc: Allocator) ![]const u8 {
 /// Ghostty <1.3.0 default path for the XDG home configuration file.
 /// Returned value must be freed by the caller.
 pub fn legacyDefaultXdgPath(alloc: Allocator) ![]const u8 {
+    var environ_map = try global.environMap();
+    defer environ_map.deinit();
     return try internal_os.xdg.config(
         alloc,
+        &environ_map,
         .{ .subdir = "ghostty/config" },
     );
 }
@@ -29,16 +36,16 @@ pub fn legacyDefaultXdgPath(alloc: Allocator) ![]const u8 {
 pub fn preferredXdgPath(alloc: Allocator) ![]const u8 {
     // If the XDG path exists, use that.
     const xdg_path = try defaultXdgPath(alloc);
-    if (open(xdg_path)) |f| {
-        f.close();
+    if (open(global.io(), xdg_path)) |f| {
+        f.close(global.io());
         return xdg_path;
     } else |_| {}
 
     // Try the legacy path
     errdefer alloc.free(xdg_path);
     const legacy_xdg_path = try legacyDefaultXdgPath(alloc);
-    if (open(legacy_xdg_path)) |f| {
-        f.close();
+    if (open(global.io(), legacy_xdg_path)) |f| {
+        f.close(global.io());
         alloc.free(xdg_path);
         return legacy_xdg_path;
     } else |_| {}
@@ -66,16 +73,16 @@ pub fn legacyDefaultAppSupportPath(alloc: Allocator) ![]const u8 {
 pub fn preferredAppSupportPath(alloc: Allocator) ![]const u8 {
     // If the app support path exists, use that.
     const app_support_path = try defaultAppSupportPath(alloc);
-    if (open(app_support_path)) |f| {
-        f.close();
+    if (open(global.io(), app_support_path)) |f| {
+        f.close(global.io());
         return app_support_path;
     } else |_| {}
 
     // Try the legacy path
     errdefer alloc.free(app_support_path);
     const legacy_app_support_path = try legacyDefaultAppSupportPath(alloc);
-    if (open(legacy_app_support_path)) |f| {
-        f.close();
+    if (open(global.io(), legacy_app_support_path)) |f| {
+        f.close(global.io());
         alloc.free(app_support_path);
         return legacy_app_support_path;
     } else |_| {}
@@ -99,19 +106,19 @@ pub fn preferredDefaultFilePath(alloc: Allocator) ![]const u8 {
             // macOS prefers the Application Support directory
             // if it exists.
             const app_support_path = try preferredAppSupportPath(alloc);
-            const app_support_file = open(app_support_path) catch {
+            const app_support_file = open(global.io(), app_support_path) catch {
                 // Try the XDG path if it exists
                 const xdg_path = try preferredXdgPath(alloc);
-                const xdg_file = open(xdg_path) catch {
+                const xdg_file = open(global.io(), xdg_path) catch {
                     // If neither file exists, use app support
                     alloc.free(xdg_path);
                     return app_support_path;
                 };
-                xdg_file.close();
+                xdg_file.close(global.io());
                 alloc.free(app_support_path);
                 return xdg_path;
             };
-            app_support_file.close();
+            app_support_file.close(global.io());
             return app_support_path;
         },
 
@@ -130,10 +137,11 @@ const OpenFileError = error{
 /// Opens the file at the given path and returns the file handle
 /// if it exists and is non-empty. This also constrains the possible
 /// errors to a smaller set that we can explicitly handle.
-pub fn open(path: []const u8) OpenFileError!std.fs.File {
+pub fn open(io: std.Io, path: []const u8) OpenFileError!std.Io.File {
     assert(std.fs.path.isAbsolute(path));
 
-    var file = std.fs.openFileAbsolute(
+    var file = std.Io.Dir.openFileAbsolute(
+        io,
         path,
         .{},
     ) catch |err| switch (err) {
@@ -146,9 +154,9 @@ pub fn open(path: []const u8) OpenFileError!std.fs.File {
             return OpenFileError.FileOpenFailed;
         },
     };
-    errdefer file.close();
+    errdefer file.close(io);
 
-    const stat = file.stat() catch |err| {
+    const stat = file.stat(io) catch |err| {
         log.warn("error getting file stat path={s} err={}", .{
             path,
             err,
diff --git a/src/config/io.zig b/src/config/io.zig
index a1e433b6a..056dc8744 100644
--- a/src/config/io.zig
+++ b/src/config/io.zig
@@ -156,7 +156,7 @@ pub const RepeatableReadableIO = struct {
     const Self = @This();
 
     // Allocator for the list is the arena for the parent config.
-    list: std.ArrayListUnmanaged(ReadableIO) = .{},
+    list: std.ArrayList(ReadableIO) = .empty,
 
     pub fn parseCLI(
         self: *Self,
diff --git a/src/config/key.zig b/src/config/key.zig
index 5709e2074..1d15c9379 100644
--- a/src/config/key.zig
+++ b/src/config/key.zig
@@ -6,29 +6,26 @@ const Config = @import("Config.zig");
 /// amongst other things.
 pub const Key = key: {
     const field_infos = std.meta.fields(Config);
-    var enumFields: [field_infos.len]std.builtin.Type.EnumField = undefined;
+    var names: [field_infos.len][]const u8 = undefined;
+    var raw_values: [field_infos.len]comptime_int = undefined;
     var i: usize = 0;
-    for (field_infos) |field| {
+    for (field_infos, &names, &raw_values) |field, *name, *raw| {
         // Ignore fields starting with "_" since they're internal and
         // not copied ever.
         if (field.name[0] == '_') continue;
 
-        enumFields[i] = .{
-            .name = field.name,
-            .value = i,
-        };
+        name.* = field.name;
+        raw.* = i;
         i += 1;
     }
 
-    var decls = [_]std.builtin.Type.Declaration{};
-    break :key @Type(.{
-        .@"enum" = .{
-            .tag_type = std.math.IntFittingRange(0, field_infos.len - 1),
-            .fields = enumFields[0..i],
-            .decls = &decls,
-            .is_exhaustive = true,
-        },
-    });
+    const TagInt = std.math.IntFittingRange(0, field_infos.len - 1);
+    var values: [i]TagInt = undefined;
+    for (raw_values[0..i], &values) |raw, *val| {
+        val.* = raw;
+    }
+
+    break :key @Enum(TagInt, .exhaustive, names[0..i], &values);
 };
 
 /// Returns the value type for a key
diff --git a/src/config/path.zig b/src/config/path.zig
index 793cf1845..4d9c8586a 100644
--- a/src/config/path.zig
+++ b/src/config/path.zig
@@ -7,6 +7,7 @@ const ArenaAllocator = std.heap.ArenaAllocator;
 const cli = @import("../cli.zig");
 const internal_os = @import("../os/main.zig");
 const formatterpkg = @import("formatter.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.config);
 
@@ -163,7 +164,11 @@ pub const Path = union(enum) {
             // Windows isn't supported yet
             if (comptime builtin.os.tag == .windows) break :expand;
 
+            var environ_map = try global.environMap();
+            defer environ_map.deinit();
+
             const expanded: []const u8 = internal_os.expandHome(
+                &environ_map,
                 path,
                 &buf,
             ) catch |err| {
@@ -195,32 +200,36 @@ pub const Path = union(enum) {
             return;
         }
 
-        var dir = try std.fs.openDirAbsolute(base, .{});
-        defer dir.close();
+        var dir = try std.Io.Dir.openDirAbsolute(global.io(), base, .{});
+        defer dir.close(global.io());
 
-        const abs = dir.realpath(path, &buf) catch |err| abs: {
-            if (err == error.FileNotFound) {
-                // The file doesn't exist. Try to resolve the relative path
-                // another way.
-                const resolved = try std.fs.path.resolve(arena_alloc, &.{ base, path });
-                defer arena_alloc.free(resolved);
-                @memcpy(buf[0..resolved.len], resolved);
-                break :abs buf[0..resolved.len];
-            }
+        const abs = abs: {
+            const abs_len = dir.realPathFile(global.io(), path, &buf) catch |err| {
+                if (err == error.FileNotFound) {
+                    // The file doesn't exist. Try to resolve the relative path
+                    // another way.
+                    const resolved = try std.fs.path.resolve(arena_alloc, &.{ base, path });
+                    defer arena_alloc.free(resolved);
+                    @memcpy(buf[0..resolved.len], resolved);
+                    break :abs buf[0..resolved.len];
+                }
 
-            try diags.append(arena_alloc, .{
-                .message = try std.fmt.allocPrintSentinel(
-                    arena_alloc,
-                    "error resolving file path {s}: {}",
-                    .{ path, err },
-                    0,
-                ),
-            });
+                try diags.append(arena_alloc, .{
+                    .message = try std.fmt.allocPrintSentinel(
+                        arena_alloc,
+                        "error resolving file path {s}: {}",
+                        .{ path, err },
+                        0,
+                    ),
+                });
 
-            // Blank this path so that we don't attempt to resolve it again
-            self.* = .{ .required = "" };
+                // Blank this path so that we don't attempt to resolve it again
+                self.* = .{ .required = "" };
 
-            return;
+                return;
+            };
+
+            break :abs buf[0..abs_len];
         };
 
         log.debug(
@@ -357,7 +366,7 @@ pub const Path = union(enum) {
 /// be automatically expanded relative to the path of the config file (or the home
 /// directory).
 pub const RepeatablePath = struct {
-    value: std.ArrayListUnmanaged(Path) = .{},
+    value: std.ArrayList(Path) = .empty,
 
     pub fn parseCLI(self: *RepeatablePath, alloc: Allocator, input: ?[]const u8) ParseError!void {
         const item = try Path.parse(alloc, input) orelse {
diff --git a/src/config/theme.zig b/src/config/theme.zig
index 8776fb1bf..e7609a165 100644
--- a/src/config/theme.zig
+++ b/src/config/theme.zig
@@ -1,9 +1,9 @@
 const std = @import("std");
 const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
-const global_state = &@import("../global.zig").state;
 const internal_os = @import("../os/main.zig");
 const cli = @import("../cli.zig");
+const global = @import("../global.zig");
 
 /// Location of possible themes. The order of this enum matters because it
 /// defines the priority of theme search (from top to bottom).
@@ -23,7 +23,9 @@ pub const Location = enum {
     pub fn dir(
         self: Location,
         arena_alloc: Allocator,
-    ) error{OutOfMemory}!?[]const u8 {
+    ) error{ OutOfMemory, Unexpected }!?[]const u8 {
+        var environ_map = try global.environMap();
+        defer environ_map.deinit();
         return switch (self) {
             .user => user: {
                 const subdir = std.fs.path.join(arena_alloc, &.{
@@ -32,6 +34,7 @@ pub const Location = enum {
 
                 break :user internal_os.xdg.config(
                     arena_alloc,
+                    &environ_map,
                     .{ .subdir = subdir },
                 ) catch |err| {
                     // We need to do some comptime tricks to get the right
@@ -55,7 +58,7 @@ pub const Location = enum {
             },
 
             .resources => try std.fs.path.join(arena_alloc, &.{
-                global_state.resources_dir.app() orelse return null,
+                global.resourcesDir().app() orelse return null,
                 "themes",
             }),
         };
@@ -111,18 +114,18 @@ pub fn open(
     arena_alloc: Allocator,
     theme: []const u8,
     diags: *cli.DiagnosticList,
-) error{OutOfMemory}!?struct {
+) error{ OutOfMemory, Unexpected }!?struct {
     path: []const u8,
-    file: std.fs.File,
+    file: std.Io.File,
 } {
     // Absolute themes are loaded a different path.
     if (std.fs.path.isAbsolute(theme)) {
-        const file: std.fs.File = try openAbsolute(
+        const file: std.Io.File = try openAbsolute(
             arena_alloc,
             theme,
             diags,
         ) orelse return null;
-        const stat = file.stat() catch |err| {
+        const stat = file.stat(global.io()) catch |err| {
             try diags.append(arena_alloc, .{
                 .message = try std.fmt.allocPrintSentinel(
                     arena_alloc,
@@ -166,11 +169,11 @@ pub fn open(
     // Iterate over the possible locations to try to find the
     // one that exists.
     var it: LocationIterator = .{ .arena_alloc = arena_alloc };
-    const cwd = std.fs.cwd();
+    const cwd = std.Io.Dir.cwd();
     while (try it.next()) |loc| {
         const path = try std.fs.path.join(arena_alloc, &.{ loc.dir, theme });
-        if (cwd.openFile(path, .{})) |file| {
-            const stat = file.stat() catch |err| {
+        if (cwd.openFile(global.io(), path, .{})) |file| {
+            const stat = file.stat(global.io()) catch |err| {
                 try diags.append(arena_alloc, .{
                     .message = try std.fmt.allocPrintSentinel(
                         arena_alloc,
@@ -251,8 +254,8 @@ pub fn openAbsolute(
     arena_alloc: Allocator,
     theme: []const u8,
     diags: *cli.DiagnosticList,
-) error{OutOfMemory}!?std.fs.File {
-    return std.fs.openFileAbsolute(theme, .{}) catch |err| {
+) error{OutOfMemory}!?std.Io.File {
+    return std.Io.Dir.openFileAbsolute(global.io(), theme, .{}) catch |err| {
         switch (err) {
             error.FileNotFound => try diags.append(arena_alloc, .{
                 .message = try std.fmt.allocPrintSentinel(
diff --git a/src/crash/dir.zig b/src/crash/dir.zig
index c0e866cdd..46e3ba2ac 100644
--- a/src/crash/dir.zig
+++ b/src/crash/dir.zig
@@ -1,11 +1,14 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
 const internal_os = @import("../os/main.zig");
+const global = @import("../global.zig");
 
 /// Returns a Dir for the default directory. The Dir.path field must be
 /// freed with the given allocator.
 pub fn defaultDir(alloc: Allocator) !Dir {
-    const crash_dir = try internal_os.xdg.state(alloc, .{ .subdir = "ghostty/crash" });
+    var environ_map = try global.environMap();
+    defer environ_map.deinit();
+    const crash_dir = try internal_os.xdg.state(alloc, &environ_map, .{ .subdir = "ghostty/crash" });
     errdefer alloc.free(crash_dir);
     return .{ .path = crash_dir };
 }
@@ -19,11 +22,12 @@ pub const Dir = struct {
     /// iterator must be freed with `ReportIterator.deinit`. The iterator
     /// may have no reports.
     pub fn iterator(self: *const Dir) !ReportIterator {
-        var dir = std.fs.openDirAbsolute(
+        var dir = std.Io.Dir.openDirAbsolute(
+            global.io(),
             self.path,
             .{ .iterate = true },
         ) catch return .{};
-        errdefer dir.close();
+        errdefer dir.close(global.io());
 
         return .{
             .dir = dir,
@@ -33,11 +37,11 @@ pub const Dir = struct {
 };
 
 pub const ReportIterator = struct {
-    dir: ?std.fs.Dir = null,
-    it: std.fs.Dir.Iterator = undefined,
+    dir: ?std.Io.Dir = null,
+    it: std.Io.Dir.Iterator = undefined,
 
     pub fn deinit(self: *ReportIterator) void {
-        if (self.dir) |dir| dir.close();
+        if (self.dir) |dir| dir.close(global.io());
     }
 
     pub fn next(self: *ReportIterator) !?Report {
@@ -46,15 +50,15 @@ pub const ReportIterator = struct {
 
         // Get the next file entry, if any.
         const entry = entry: while (true) {
-            const entry = try self.it.next() orelse return null;
+            const entry = try self.it.next(global.io()) orelse return null;
             if (entry.kind != .file) continue;
             break :entry entry;
         };
 
-        const stat = try dir.statFile(entry.name);
+        const stat = try dir.statFile(global.io(), entry.name, .{});
         return .{
             .name = entry.name,
-            .mtime = stat.mtime,
+            .mtime = stat.mtime.toNanoseconds(),
         };
     }
 };
diff --git a/src/crash/sentry.zig b/src/crash/sentry.zig
index 555b70fe9..b0ad68937 100644
--- a/src/crash/sentry.zig
+++ b/src/crash/sentry.zig
@@ -7,7 +7,7 @@ const build_options = @import("build_options");
 const sentry = if (build_options.sentry) @import("sentry");
 const internal_os = @import("../os/main.zig");
 const crash = @import("main.zig");
-const state = &@import("../global.zig").state;
+const global = @import("../global.zig");
 const Surface = @import("../Surface.zig");
 
 const log = std.log.scoped(.sentry);
@@ -53,14 +53,6 @@ pub fn init(gpa: Allocator) !void {
     // Not supported on Windows currently, doesn't build.
     if (comptime builtin.os.tag == .windows) return;
 
-    // const start = try std.time.Instant.now();
-    // const start_micro = std.time.microTimestamp();
-    // defer {
-    //     const end = std.time.Instant.now() catch unreachable;
-    //     // "[updateFrame critical time] <START us>\t<TIME_TAKEN us>"
-    //     std.log.err("[sentry init time] start={}us duration={}ns", .{ start_micro, end.since(start) / std.time.ns_per_us });
-    // }
-
     // Must only start once
     assert(init_thread == null);
 
@@ -74,7 +66,7 @@ pub fn init(gpa: Allocator) !void {
         initThread,
         .{gpa},
     );
-    thr.setName("sentry-init") catch {};
+    thr.setName(global.io(), "sentry-init") catch {};
     init_thread = thr;
 }
 
@@ -118,15 +110,18 @@ fn initThread(gpa: Allocator) !void {
         // a more idiomatic macOS application. But if XDG env vars are set
         // we will respect them.
         if (comptime builtin.os.tag == .macos) macos: {
-            if (std.posix.getenv("XDG_CACHE_HOME") != null) break :macos;
+            if (global.environ().containsUnemptyConstant("XDG_CACHE_HOME")) break :macos;
             break :cache_dir try internal_os.macos.cacheDir(
                 alloc,
                 "sentry",
             );
         }
 
+        var environ_map = try global.environMap();
+        defer environ_map.deinit();
         break :cache_dir try internal_os.xdg.cache(
             alloc,
+            &environ_map,
             .{ .subdir = "ghostty/sentry" },
         );
     };
@@ -257,7 +252,7 @@ pub const Transport = struct {
 
     /// Implementation of send but we can use Zig errors.
     fn sendInternal(envelope: *sentry.Envelope) !void {
-        var arena = std.heap.ArenaAllocator.init(state.alloc);
+        var arena = std.heap.ArenaAllocator.init(global.alloc());
         defer arena.deinit();
         const alloc = arena.allocator();
 
@@ -289,17 +284,17 @@ pub const Transport = struct {
         // Get our XDG state directory where we'll store the crash reports.
         // This directory must exist for writing to work.
         const dir = try crash.defaultDir(alloc);
-        try std.fs.cwd().makePath(dir.path);
+        try std.Io.Dir.cwd().createDirPath(global.io(), dir.path);
 
         // Build our final path and write to it.
         const path = try std.fs.path.join(alloc, &.{
             dir.path,
             try std.fmt.allocPrint(alloc, "{s}.ghosttycrash", .{uuid.string()}),
         });
-        const file = try std.fs.cwd().createFile(path, .{});
-        defer file.close();
+        const file = try std.Io.Dir.cwd().createFile(global.io(), path, .{});
+        defer file.close(global.io());
         var buf: [4096]u8 = undefined;
-        var file_writer = file.writer(&buf);
+        var file_writer = file.writer(global.io(), &buf);
         try file_writer.interface.writeAll(json);
         try file_writer.end();
 
diff --git a/src/crash/sentry_envelope.zig b/src/crash/sentry_envelope.zig
index 08573b739..0472bcbe1 100644
--- a/src/crash/sentry_envelope.zig
+++ b/src/crash/sentry_envelope.zig
@@ -93,7 +93,7 @@ pub const Envelope = struct {
         alloc: Allocator,
         reader: *std.Io.Reader,
     ) !std.ArrayList(Item) {
-        var items: std.ArrayList(Item) = .{};
+        var items: std.ArrayList(Item) = .empty;
         errdefer items.deinit(alloc);
         while (try parseOneItem(alloc, reader)) |item| {
             try items.append(alloc, item);
@@ -391,7 +391,7 @@ pub const Attachment = struct {
                 else => return error.InvalidFieldType,
             } else null,
 
-            .headers_extra = item.headers.unmanaged,
+            .headers_extra = item.headers,
             .payload = item.payload,
         };
     }
@@ -417,7 +417,7 @@ pub const Attachment = struct {
         }
 
         return .{
-            .headers = self.headers_extra.promote(alloc),
+            .headers = self.headers_extra,
             .type = .attachment,
             .payload = self.payload,
         };
diff --git a/src/datastruct/blocking_queue.zig b/src/datastruct/blocking_queue.zig
index 3185d98d1..89ce57d8c 100644
--- a/src/datastruct/blocking_queue.zig
+++ b/src/datastruct/blocking_queue.zig
@@ -3,6 +3,7 @@
 
 const std = @import("std");
 const Allocator = std.mem.Allocator;
+const compat_thread = @import("../lib/compat/thread.zig");
 
 /// Returns a blocking queue implementation for type T.
 ///
@@ -62,12 +63,12 @@ pub fn BlockingQueue(
         len: Size = 0,
 
         /// The big mutex that must be held to read/write.
-        mutex: std.Thread.Mutex = .{},
+        mutex: std.Io.Mutex = .init,
 
         /// A CV for being notified when the queue is no longer full. This is
         /// used for writing. Note we DON'T have a CV for waiting on the
         /// queue not being EMPTY because we use external notifiers for that.
-        cond_not_full: std.Thread.Condition = .{},
+        cond_not_full: std.Io.Condition = .init,
         not_full_waiters: usize = 0,
 
         /// Allocate the blocking queue on the heap.
@@ -80,8 +81,8 @@ pub fn BlockingQueue(
                 .len = 0,
                 .write = 0,
                 .read = 0,
-                .mutex = .{},
-                .cond_not_full = .{},
+                .mutex = .init,
+                .cond_not_full = .init,
                 .not_full_waiters = 0,
             };
 
@@ -98,9 +99,9 @@ pub fn BlockingQueue(
         /// Push a value to the queue. This returns the total size of the
         /// queue (unread items) after the push. A return value of zero
         /// means that the push failed.
-        pub fn push(self: *Self, value: T, timeout: Timeout) Size {
-            self.mutex.lock();
-            defer self.mutex.unlock();
+        pub fn push(self: *Self, io: std.Io, value: T, timeout: Timeout) Size {
+            self.mutex.lockUncancelable(io);
+            defer self.mutex.unlock(io);
 
             // The
             if (self.full()) {
@@ -111,13 +112,23 @@ pub fn BlockingQueue(
                     .forever => {
                         self.not_full_waiters += 1;
                         defer self.not_full_waiters -= 1;
-                        self.cond_not_full.wait(&self.mutex);
+                        self.cond_not_full.waitUncancelable(io, &self.mutex);
                     },
 
                     .ns => |ns| {
                         self.not_full_waiters += 1;
                         defer self.not_full_waiters -= 1;
-                        self.cond_not_full.timedWait(&self.mutex, ns) catch return 0;
+                        compat_thread.waitTimeout(
+                            &self.cond_not_full,
+                            io,
+                            &self.mutex,
+                            .{
+                                .duration = .{
+                                    .raw = .fromNanoseconds(ns),
+                                    .clock = .awake,
+                                },
+                            },
+                        ) catch return 0;
                     },
                 }
 
@@ -136,9 +147,9 @@ pub fn BlockingQueue(
         }
 
         /// Pop a value from the queue without blocking.
-        pub fn pop(self: *Self) ?T {
-            self.mutex.lock();
-            defer self.mutex.unlock();
+        pub fn pop(self: *Self, io: std.Io) ?T {
+            self.mutex.lockUncancelable(io);
+            defer self.mutex.unlock(io);
 
             // If we're empty we have nothing
             if (self.len == 0) return null;
@@ -151,7 +162,7 @@ pub fn BlockingQueue(
             self.len -= 1;
 
             // If we have consumers waiting on a full queue, notify.
-            if (self.not_full_waiters > 0) self.cond_not_full.signal();
+            if (self.not_full_waiters > 0) self.cond_not_full.signal(io);
 
             return self.data[n];
         }
@@ -160,8 +171,8 @@ pub fn BlockingQueue(
         /// until `deinit` is called on the return value. This is used if
         /// you know you're going to "pop" and utilize all the values
         /// quickly to avoid many locks, bounds checks, and cv signals.
-        pub fn drain(self: *Self) DrainIterator {
-            self.mutex.lock();
+        pub fn drain(self: *Self, io: std.Io) DrainIterator {
+            self.mutex.lockUncancelable(io);
             return .{ .queue = self };
         }
 
@@ -180,12 +191,12 @@ pub fn BlockingQueue(
                 return self.queue.data[n];
             }
 
-            pub fn deinit(self: *DrainIterator) void {
+            pub fn deinit(self: *DrainIterator, io: std.Io) void {
                 // If we have consumers waiting on a full queue, notify.
-                if (self.queue.not_full_waiters > 0) self.queue.cond_not_full.signal();
+                if (self.queue.not_full_waiters > 0) self.queue.cond_not_full.signal(io);
 
                 // Unlock
-                self.queue.mutex.unlock();
+                self.queue.mutex.unlock(io);
             }
         };
 
@@ -200,49 +211,51 @@ pub fn BlockingQueue(
 test "basic push and pop" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     const Q = BlockingQueue(u64, 4);
     const q = try Q.create(alloc);
     defer q.destroy(alloc);
 
     // Should have no values
-    try testing.expect(q.pop() == null);
+    try testing.expect(q.pop(io) == null);
 
     // Push until we're full
-    try testing.expectEqual(@as(Q.Size, 1), q.push(1, .{ .instant = {} }));
-    try testing.expectEqual(@as(Q.Size, 2), q.push(2, .{ .instant = {} }));
-    try testing.expectEqual(@as(Q.Size, 3), q.push(3, .{ .instant = {} }));
-    try testing.expectEqual(@as(Q.Size, 4), q.push(4, .{ .instant = {} }));
-    try testing.expectEqual(@as(Q.Size, 0), q.push(5, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 1), q.push(io, 1, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 2), q.push(io, 2, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 3), q.push(io, 3, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 4), q.push(io, 4, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 0), q.push(io, 5, .{ .instant = {} }));
 
     // Pop!
-    try testing.expect(q.pop().? == 1);
-    try testing.expect(q.pop().? == 2);
-    try testing.expect(q.pop().? == 3);
-    try testing.expect(q.pop().? == 4);
-    try testing.expect(q.pop() == null);
+    try testing.expect(q.pop(io).? == 1);
+    try testing.expect(q.pop(io).? == 2);
+    try testing.expect(q.pop(io).? == 3);
+    try testing.expect(q.pop(io).? == 4);
+    try testing.expect(q.pop(io) == null);
 
     // Drain does nothing
-    var it = q.drain();
+    var it = q.drain(io);
     try testing.expect(it.next() == null);
-    it.deinit();
+    it.deinit(io);
 
     // Verify we can still push
-    try testing.expectEqual(@as(Q.Size, 1), q.push(1, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 1), q.push(io, 1, .{ .instant = {} }));
 }
 
 test "timed push" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     const Q = BlockingQueue(u64, 1);
     const q = try Q.create(alloc);
     defer q.destroy(alloc);
 
     // Push
-    try testing.expectEqual(@as(Q.Size, 1), q.push(1, .{ .instant = {} }));
-    try testing.expectEqual(@as(Q.Size, 0), q.push(2, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 1), q.push(io, 1, .{ .instant = {} }));
+    try testing.expectEqual(@as(Q.Size, 0), q.push(io, 2, .{ .instant = {} }));
 
     // Timed push should fail
-    try testing.expectEqual(@as(Q.Size, 0), q.push(2, .{ .ns = 1000 }));
+    try testing.expectEqual(@as(Q.Size, 0), q.push(io, 2, .{ .ns = 1000 }));
 }
diff --git a/src/datastruct/comparison.zig b/src/datastruct/comparison.zig
index 6a862bb9c..73f0a5bdc 100644
--- a/src/datastruct/comparison.zig
+++ b/src/datastruct/comparison.zig
@@ -130,10 +130,12 @@ fn expectApproxEqualInner(comptime T: type, expected: T, actual: T) !void {
         },
         .vector => |info| {
             var i: usize = 0;
+            const expected_array: [info.len]info.child = expected;
+            const actual_array: [info.len]info.child = actual;
             while (i < info.len) : (i += 1) {
-                expectApproxEqual(expected[i], actual[i]) catch {
+                expectApproxEqual(expected_array[i], actual_array[i]) catch {
                     print("index {d} incorrect. expected approximately {any}, found {any}\n", .{
-                        i, expected[i], actual[i],
+                        i, expected_array[i], actual_array[i],
                     });
                     return error.TestExpectedApproxEqual;
                 };
diff --git a/src/datastruct/segmented_list.zig b/src/datastruct/segmented_list.zig
new file mode 100644
index 000000000..5c0601c57
--- /dev/null
+++ b/src/datastruct/segmented_list.zig
@@ -0,0 +1,533 @@
+//! Code taken from 0.15.2 `std.segmented_list` (MIT license). See
+//! lib/compat/README.md for license and details.
+const std = @import("std");
+const assert = @import("../quirks.zig").inlineAssert;
+const testing = std.testing;
+const mem = std.mem;
+const Allocator = std.mem.Allocator;
+
+// Imagine that `fn at(self: *Self, index: usize) &T` is a customer asking for a box
+// from a warehouse, based on a flat array, boxes ordered from 0 to N - 1.
+// But the warehouse actually stores boxes in shelves of increasing powers of 2 sizes.
+// So when the customer requests a box index, we have to translate it to shelf index
+// and box index within that shelf. Illustration:
+//
+// customer indexes:
+// shelf 0:  0
+// shelf 1:  1  2
+// shelf 2:  3  4  5  6
+// shelf 3:  7  8  9 10 11 12 13 14
+// shelf 4: 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
+// shelf 5: 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
+// ...
+//
+// warehouse indexes:
+// shelf 0:  0
+// shelf 1:  0  1
+// shelf 2:  0  1  2  3
+// shelf 3:  0  1  2  3  4  5  6  7
+// shelf 4:  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
+// shelf 5:  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
+// ...
+//
+// With this arrangement, here are the equations to get the shelf index and
+// box index based on customer box index:
+//
+// shelf_index = floor(log2(customer_index + 1))
+// shelf_count = ceil(log2(box_count + 1))
+// box_index = customer_index + 1 - 2 ** shelf
+// shelf_size = 2 ** shelf_index
+//
+// Now we complicate it a little bit further by adding a preallocated shelf, which must be
+// a power of 2:
+// prealloc=4
+//
+// customer indexes:
+// prealloc:  0  1  2  3
+//  shelf 0:  4  5  6  7  8  9 10 11
+//  shelf 1: 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
+//  shelf 2: 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59
+// ...
+//
+// warehouse indexes:
+// prealloc:  0  1  2  3
+//  shelf 0:  0  1  2  3  4  5  6  7
+//  shelf 1:  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
+//  shelf 2:  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
+// ...
+//
+// Now the equations are:
+//
+// shelf_index = floor(log2(customer_index + prealloc)) - log2(prealloc) - 1
+// shelf_count = ceil(log2(box_count + prealloc)) - log2(prealloc) - 1
+// box_index = customer_index + prealloc - 2 ** (log2(prealloc) + 1 + shelf)
+// shelf_size = prealloc * 2 ** (shelf_index + 1)
+
+/// This is a stack data structure where pointers to indexes have the same lifetime as the data structure
+/// itself, unlike ArrayList where append() invalidates all existing element pointers.
+/// The tradeoff is that elements are not guaranteed to be contiguous. For that, use ArrayList.
+/// Note however that most elements are contiguous, making this data structure cache-friendly.
+///
+/// Because it never has to copy elements from an old location to a new location, it does not require
+/// its elements to be copyable, and it avoids wasting memory when backed by an ArenaAllocator.
+/// Note that the append() and pop() convenience methods perform a copy, but you can instead use
+/// addOne(), at(), setCapacity(), and shrinkCapacity() to avoid copying items.
+///
+/// This data structure has O(1) append and O(1) pop.
+///
+/// It supports preallocated elements, making it especially well suited when the expected maximum
+/// size is small. `prealloc_item_count` must be 0, or a power of 2.
+pub fn SegmentedList(comptime T: type, comptime prealloc_item_count: usize) type {
+    return struct {
+        const Self = @This();
+        const ShelfIndex = std.math.Log2Int(usize);
+
+        const prealloc_exp: ShelfIndex = blk: {
+            // we don't use the prealloc_exp constant when prealloc_item_count is 0
+            // but lazy-init may still be triggered by other code so supply a value
+            if (prealloc_item_count == 0) {
+                break :blk 0;
+            } else {
+                assert(std.math.isPowerOfTwo(prealloc_item_count));
+                const value = std.math.log2_int(usize, prealloc_item_count);
+                break :blk value;
+            }
+        };
+
+        prealloc_segment: [prealloc_item_count]T = undefined,
+        dynamic_segments: [][*]T = &[_][*]T{},
+        len: usize = 0,
+
+        pub const prealloc_count = prealloc_item_count;
+
+        fn AtType(comptime SelfType: type) type {
+            if (@typeInfo(SelfType).pointer.is_const) {
+                return *const T;
+            } else {
+                return *T;
+            }
+        }
+
+        pub fn deinit(self: *Self, allocator: Allocator) void {
+            self.freeShelves(allocator, @as(ShelfIndex, @intCast(self.dynamic_segments.len)), 0);
+            allocator.free(self.dynamic_segments);
+            self.* = undefined;
+        }
+
+        pub fn at(self: anytype, i: usize) AtType(@TypeOf(self)) {
+            assert(i < self.len);
+            return self.uncheckedAt(i);
+        }
+
+        pub fn count(self: Self) usize {
+            return self.len;
+        }
+
+        pub fn append(self: *Self, allocator: Allocator, item: T) Allocator.Error!void {
+            const new_item_ptr = try self.addOne(allocator);
+            new_item_ptr.* = item;
+        }
+
+        pub fn appendSlice(self: *Self, allocator: Allocator, items: []const T) Allocator.Error!void {
+            for (items) |item| {
+                try self.append(allocator, item);
+            }
+        }
+
+        pub fn pop(self: *Self) ?T {
+            if (self.len == 0) return null;
+
+            const index = self.len - 1;
+            const result = uncheckedAt(self, index).*;
+            self.len = index;
+            return result;
+        }
+
+        pub fn addOne(self: *Self, allocator: Allocator) Allocator.Error!*T {
+            const new_length = self.len + 1;
+            try self.growCapacity(allocator, new_length);
+            const result = uncheckedAt(self, self.len);
+            self.len = new_length;
+            return result;
+        }
+
+        /// Reduce length to `new_len`.
+        /// Invalidates pointers for the elements at index new_len and beyond.
+        pub fn shrinkRetainingCapacity(self: *Self, new_len: usize) void {
+            assert(new_len <= self.len);
+            self.len = new_len;
+        }
+
+        /// Invalidates all element pointers.
+        pub fn clearRetainingCapacity(self: *Self) void {
+            self.len = 0;
+        }
+
+        /// Invalidates all element pointers.
+        pub fn clearAndFree(self: *Self, allocator: Allocator) void {
+            self.setCapacity(allocator, 0) catch unreachable;
+            self.len = 0;
+        }
+
+        /// Grows or shrinks capacity to match usage.
+        /// TODO update this and related methods to match the conventions set by ArrayList
+        pub fn setCapacity(self: *Self, allocator: Allocator, new_capacity: usize) Allocator.Error!void {
+            if (prealloc_item_count != 0) {
+                if (new_capacity <= @as(usize, 1) << (prealloc_exp + @as(ShelfIndex, @intCast(self.dynamic_segments.len)))) {
+                    return self.shrinkCapacity(allocator, new_capacity);
+                }
+            }
+            return self.growCapacity(allocator, new_capacity);
+        }
+
+        /// Only grows capacity, or retains current capacity.
+        pub fn growCapacity(self: *Self, allocator: Allocator, new_capacity: usize) Allocator.Error!void {
+            const new_cap_shelf_count = shelfCount(new_capacity);
+            const old_shelf_count = @as(ShelfIndex, @intCast(self.dynamic_segments.len));
+            if (new_cap_shelf_count <= old_shelf_count) return;
+
+            const new_dynamic_segments = try allocator.alloc([*]T, new_cap_shelf_count);
+            errdefer allocator.free(new_dynamic_segments);
+
+            var i: ShelfIndex = 0;
+            while (i < old_shelf_count) : (i += 1) {
+                new_dynamic_segments[i] = self.dynamic_segments[i];
+            }
+            errdefer while (i > old_shelf_count) : (i -= 1) {
+                allocator.free(new_dynamic_segments[i][0..shelfSize(i)]);
+            };
+            while (i < new_cap_shelf_count) : (i += 1) {
+                new_dynamic_segments[i] = (try allocator.alloc(T, shelfSize(i))).ptr;
+            }
+
+            allocator.free(self.dynamic_segments);
+            self.dynamic_segments = new_dynamic_segments;
+        }
+
+        /// Only shrinks capacity or retains current capacity.
+        /// It may fail to reduce the capacity in which case the capacity will remain unchanged.
+        pub fn shrinkCapacity(self: *Self, allocator: Allocator, new_capacity: usize) void {
+            if (new_capacity <= prealloc_item_count) {
+                const len = @as(ShelfIndex, @intCast(self.dynamic_segments.len));
+                self.freeShelves(allocator, len, 0);
+                allocator.free(self.dynamic_segments);
+                self.dynamic_segments = &[_][*]T{};
+                return;
+            }
+
+            const new_cap_shelf_count = shelfCount(new_capacity);
+            const old_shelf_count = @as(ShelfIndex, @intCast(self.dynamic_segments.len));
+            assert(new_cap_shelf_count <= old_shelf_count);
+            if (new_cap_shelf_count == old_shelf_count) return;
+
+            // freeShelves() must be called before resizing the dynamic
+            // segments, but we don't know if resizing the dynamic segments
+            // will work until we try it. So we must allocate a fresh memory
+            // buffer in order to reduce capacity.
+            const new_dynamic_segments = allocator.alloc([*]T, new_cap_shelf_count) catch return;
+            self.freeShelves(allocator, old_shelf_count, new_cap_shelf_count);
+            if (allocator.resize(self.dynamic_segments, new_cap_shelf_count)) {
+                // We didn't need the new memory allocation after all.
+                self.dynamic_segments = self.dynamic_segments[0..new_cap_shelf_count];
+                allocator.free(new_dynamic_segments);
+            } else {
+                // Good thing we allocated that new memory slice.
+                @memcpy(new_dynamic_segments, self.dynamic_segments[0..new_cap_shelf_count]);
+                allocator.free(self.dynamic_segments);
+                self.dynamic_segments = new_dynamic_segments;
+            }
+        }
+
+        pub fn shrink(self: *Self, new_len: usize) void {
+            assert(new_len <= self.len);
+            // TODO take advantage of the new realloc semantics
+            self.len = new_len;
+        }
+
+        pub fn writeToSlice(self: *Self, dest: []T, start: usize) void {
+            const end = start + dest.len;
+            assert(end <= self.len);
+
+            var i = start;
+            if (end <= prealloc_item_count) {
+                const src = self.prealloc_segment[i..end];
+                @memcpy(dest[i - start ..][0..src.len], src);
+                return;
+            } else if (i < prealloc_item_count) {
+                const src = self.prealloc_segment[i..];
+                @memcpy(dest[i - start ..][0..src.len], src);
+                i = prealloc_item_count;
+            }
+
+            while (i < end) {
+                const shelf_index = shelfIndex(i);
+                const copy_start = boxIndex(i, shelf_index);
+                const copy_end = @min(shelfSize(shelf_index), copy_start + end - i);
+                const src = self.dynamic_segments[shelf_index][copy_start..copy_end];
+                @memcpy(dest[i - start ..][0..src.len], src);
+                i += (copy_end - copy_start);
+            }
+        }
+
+        pub fn uncheckedAt(self: anytype, index: usize) AtType(@TypeOf(self)) {
+            if (index < prealloc_item_count) {
+                return &self.prealloc_segment[index];
+            }
+            const shelf_index = shelfIndex(index);
+            const box_index = boxIndex(index, shelf_index);
+            return &self.dynamic_segments[shelf_index][box_index];
+        }
+
+        fn shelfCount(box_count: usize) ShelfIndex {
+            if (prealloc_item_count == 0) {
+                return log2_int_ceil(usize, box_count + 1);
+            }
+            return log2_int_ceil(usize, box_count + prealloc_item_count) - prealloc_exp - 1;
+        }
+
+        fn shelfSize(shelf_index: ShelfIndex) usize {
+            if (prealloc_item_count == 0) {
+                return @as(usize, 1) << shelf_index;
+            }
+            return @as(usize, 1) << (shelf_index + (prealloc_exp + 1));
+        }
+
+        fn shelfIndex(list_index: usize) ShelfIndex {
+            if (prealloc_item_count == 0) {
+                return std.math.log2_int(usize, list_index + 1);
+            }
+            return std.math.log2_int(usize, list_index + prealloc_item_count) - prealloc_exp - 1;
+        }
+
+        fn boxIndex(list_index: usize, shelf_index: ShelfIndex) usize {
+            if (prealloc_item_count == 0) {
+                return (list_index + 1) - (@as(usize, 1) << shelf_index);
+            }
+            return list_index + prealloc_item_count - (@as(usize, 1) << ((prealloc_exp + 1) + shelf_index));
+        }
+
+        fn freeShelves(self: *Self, allocator: Allocator, from_count: ShelfIndex, to_count: ShelfIndex) void {
+            var i = from_count;
+            while (i != to_count) {
+                i -= 1;
+                allocator.free(self.dynamic_segments[i][0..shelfSize(i)]);
+            }
+        }
+
+        pub const Iterator = BaseIterator(*Self, *T);
+        pub const ConstIterator = BaseIterator(*const Self, *const T);
+        fn BaseIterator(comptime SelfType: type, comptime ElementPtr: type) type {
+            return struct {
+                list: SelfType,
+                index: usize,
+                box_index: usize,
+                shelf_index: ShelfIndex,
+                shelf_size: usize,
+
+                pub fn next(it: *@This()) ?ElementPtr {
+                    if (it.index >= it.list.len) return null;
+                    if (it.index < prealloc_item_count) {
+                        const ptr = &it.list.prealloc_segment[it.index];
+                        it.index += 1;
+                        if (it.index == prealloc_item_count) {
+                            it.box_index = 0;
+                            it.shelf_index = 0;
+                            it.shelf_size = prealloc_item_count * 2;
+                        }
+                        return ptr;
+                    }
+
+                    const ptr = &it.list.dynamic_segments[it.shelf_index][it.box_index];
+                    it.index += 1;
+                    it.box_index += 1;
+                    if (it.box_index == it.shelf_size) {
+                        it.shelf_index += 1;
+                        it.box_index = 0;
+                        it.shelf_size *= 2;
+                    }
+                    return ptr;
+                }
+
+                pub fn prev(it: *@This()) ?ElementPtr {
+                    if (it.index == 0) return null;
+
+                    it.index -= 1;
+                    if (it.index < prealloc_item_count) return &it.list.prealloc_segment[it.index];
+
+                    if (it.box_index == 0) {
+                        it.shelf_index -= 1;
+                        it.shelf_size /= 2;
+                        it.box_index = it.shelf_size - 1;
+                    } else {
+                        it.box_index -= 1;
+                    }
+
+                    return &it.list.dynamic_segments[it.shelf_index][it.box_index];
+                }
+
+                pub fn peek(it: *@This()) ?ElementPtr {
+                    if (it.index >= it.list.len)
+                        return null;
+                    if (it.index < prealloc_item_count)
+                        return &it.list.prealloc_segment[it.index];
+
+                    return &it.list.dynamic_segments[it.shelf_index][it.box_index];
+                }
+
+                pub fn set(it: *@This(), index: usize) void {
+                    it.index = index;
+                    if (index < prealloc_item_count) return;
+                    it.shelf_index = shelfIndex(index);
+                    it.box_index = boxIndex(index, it.shelf_index);
+                    it.shelf_size = shelfSize(it.shelf_index);
+                }
+            };
+        }
+
+        pub fn iterator(self: *Self, start_index: usize) Iterator {
+            var it = Iterator{
+                .list = self,
+                .index = undefined,
+                .shelf_index = undefined,
+                .box_index = undefined,
+                .shelf_size = undefined,
+            };
+            it.set(start_index);
+            return it;
+        }
+
+        pub fn constIterator(self: *const Self, start_index: usize) ConstIterator {
+            var it = ConstIterator{
+                .list = self,
+                .index = undefined,
+                .shelf_index = undefined,
+                .box_index = undefined,
+                .shelf_size = undefined,
+            };
+            it.set(start_index);
+            return it;
+        }
+    };
+}
+
+test "basic usage" {
+    try testSegmentedList(0);
+    try testSegmentedList(1);
+    try testSegmentedList(2);
+    try testSegmentedList(4);
+    try testSegmentedList(8);
+    try testSegmentedList(16);
+}
+
+fn testSegmentedList(comptime prealloc: usize) !void {
+    var list = SegmentedList(i32, prealloc){};
+    defer list.deinit(testing.allocator);
+
+    {
+        var i: usize = 0;
+        while (i < 100) : (i += 1) {
+            try list.append(testing.allocator, @as(i32, @intCast(i + 1)));
+            try testing.expect(list.len == i + 1);
+        }
+    }
+
+    {
+        var i: usize = 0;
+        while (i < 100) : (i += 1) {
+            try testing.expect(list.at(i).* == @as(i32, @intCast(i + 1)));
+        }
+    }
+
+    {
+        var it = list.iterator(0);
+        var x: i32 = 0;
+        while (it.next()) |item| {
+            x += 1;
+            try testing.expect(item.* == x);
+        }
+        try testing.expect(x == 100);
+        while (it.prev()) |item| : (x -= 1) {
+            try testing.expect(item.* == x);
+        }
+        try testing.expect(x == 0);
+    }
+
+    {
+        var it = list.constIterator(0);
+        var x: i32 = 0;
+        while (it.next()) |item| {
+            x += 1;
+            try testing.expect(item.* == x);
+        }
+        try testing.expect(x == 100);
+        while (it.prev()) |item| : (x -= 1) {
+            try testing.expect(item.* == x);
+        }
+        try testing.expect(x == 0);
+    }
+
+    try testing.expect(list.pop().? == 100);
+    try testing.expect(list.len == 99);
+
+    try list.appendSlice(testing.allocator, &[_]i32{ 1, 2, 3 });
+    try testing.expect(list.len == 102);
+    try testing.expect(list.pop().? == 3);
+    try testing.expect(list.pop().? == 2);
+    try testing.expect(list.pop().? == 1);
+    try testing.expect(list.len == 99);
+
+    try list.appendSlice(testing.allocator, &[_]i32{});
+    try testing.expect(list.len == 99);
+
+    {
+        var i: i32 = 99;
+        while (list.pop()) |item| : (i -= 1) {
+            try testing.expect(item == i);
+            list.shrinkCapacity(testing.allocator, list.len);
+        }
+    }
+
+    {
+        var control: [100]i32 = undefined;
+        var dest: [100]i32 = undefined;
+
+        var i: i32 = 0;
+        while (i < 100) : (i += 1) {
+            try list.append(testing.allocator, i + 1);
+            control[@as(usize, @intCast(i))] = i + 1;
+        }
+
+        @memset(dest[0..], 0);
+        list.writeToSlice(dest[0..], 0);
+        try testing.expect(mem.eql(i32, control[0..], dest[0..]));
+
+        @memset(dest[0..], 0);
+        list.writeToSlice(dest[50..], 50);
+        try testing.expect(mem.eql(i32, control[50..], dest[50..]));
+    }
+
+    try list.setCapacity(testing.allocator, 0);
+}
+
+test "clearRetainingCapacity" {
+    var list = SegmentedList(i32, 1){};
+    defer list.deinit(testing.allocator);
+
+    try list.appendSlice(testing.allocator, &[_]i32{ 4, 5 });
+    list.clearRetainingCapacity();
+    try list.append(testing.allocator, 6);
+    try testing.expect(list.at(0).* == 6);
+    try testing.expect(list.len == 1);
+    list.clearRetainingCapacity();
+    try testing.expect(list.len == 0);
+}
+
+/// TODO look into why this std.math function was changed in
+/// fc9430f56798a53f9393a697f4ccd6bf9981b970.
+fn log2_int_ceil(comptime T: type, x: T) std.math.Log2Int(T) {
+    assert(x != 0);
+    const log2_val = std.math.log2_int(T, x);
+    if (@as(T, 1) << log2_val == x)
+        return log2_val;
+    return log2_val + 1;
+}
diff --git a/src/datastruct/segmented_pool.zig b/src/datastruct/segmented_pool.zig
index 328eb2398..4ffc5d59f 100644
--- a/src/datastruct/segmented_pool.zig
+++ b/src/datastruct/segmented_pool.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const assert = @import("../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
+const SegmentedList = @import("segmented_list.zig").SegmentedList;
 const testing = std.testing;
 
 /// A data structure where you can get stable (never copied) pointers to
@@ -18,7 +19,7 @@ pub fn SegmentedPool(comptime T: type, comptime prealloc: usize) type {
 
         i: usize = 0,
         available: usize = prealloc,
-        list: std.SegmentedList(T, prealloc) = .{ .len = prealloc },
+        list: SegmentedList(T, prealloc) = .{ .len = prealloc },
 
         pub fn deinit(self: *Self, alloc: Allocator) void {
             self.list.deinit(alloc);
diff --git a/src/font/Atlas.zig b/src/font/Atlas.zig
index d12064576..66e91c8f8 100644
--- a/src/font/Atlas.zig
+++ b/src/font/Atlas.zig
@@ -32,7 +32,7 @@ data: []u8,
 size: u32 = 0,
 
 /// The nodes (rectangles) of available space.
-nodes: std.ArrayListUnmanaged(Node) = .{},
+nodes: std.ArrayList(Node) = .empty,
 
 /// The format of the texture data being written into the Atlas. This must be
 /// uniform for all textures in the Atlas. If you have some textures with
@@ -104,7 +104,7 @@ pub fn init(alloc: Allocator, size: u32, format: Format) Allocator.Error!Atlas {
     var result = Atlas{
         .data = try alloc.alloc(u8, size * size * format.depth()),
         .size = size,
-        .nodes = .{},
+        .nodes = .empty,
         .format = format,
     };
     errdefer result.deinit(alloc);
diff --git a/src/font/Collection.zig b/src/font/Collection.zig
index 5d7bfa519..6c646d9f6 100644
--- a/src/font/Collection.zig
+++ b/src/font/Collection.zig
@@ -28,6 +28,7 @@ const Library = font.Library;
 const Metrics = font.Metrics;
 const Presentation = font.Presentation;
 const Style = font.Style;
+const SegmentedList = @import("../datastruct/segmented_list.zig").SegmentedList;
 
 const log = std.log.scoped(.font_collection);
 
@@ -662,7 +663,7 @@ fn scaleFactor(
     return primary_metric / face_metric;
 }
 
-const UpdateMetricsError = error{
+pub const UpdateMetricsError = error{
     CannotLoadPrimaryFont,
 };
 
@@ -694,7 +695,7 @@ pub fn updateMetrics(self: *Collection) UpdateMetricsError!void {
 ///
 /// WARNING: We cannot use any prealloc yet for the segmented list because
 /// the collection is copied around by value and pointers aren't stable.
-const StyleArray = std.EnumArray(Style, std.SegmentedList(EntryOrAlias, 0));
+const StyleArray = std.EnumArray(Style, SegmentedList(EntryOrAlias, 0));
 
 /// Load options are used to configure all the details a Collection
 /// needs to load deferred faces.
@@ -894,7 +895,7 @@ pub const Index = packed struct(Index.Backing) {
 
     /// The number of bits we use for the index.
     const idx_bits = backing_bits - @typeInfo(@typeInfo(Style).@"enum".tag_type).int.bits;
-    pub const IndexInt = @Type(.{ .int = .{ .signedness = .unsigned, .bits = idx_bits } });
+    pub const IndexInt = @Int(.unsigned, idx_bits);
 
     /// The special-case fonts that we support.
     pub const Special = enum(IndexInt) {
diff --git a/src/font/Metrics.zig b/src/font/Metrics.zig
index 60a300b0c..36cfe0093 100644
--- a/src/font/Metrics.zig
+++ b/src/font/Metrics.zig
@@ -589,23 +589,21 @@ pub const Modifier = union(enum) {
 /// Key is an enum of all the available metrics keys.
 pub const Key = key: {
     const field_infos = std.meta.fields(Metrics);
-    var enumFields: [field_infos.len]std.builtin.Type.EnumField = undefined;
+    var names: [field_infos.len][]const u8 = undefined;
+    var raw_values: [field_infos.len]comptime_int = undefined;
     var count: usize = 0;
-    for (field_infos, 0..) |field, i| {
+    for (field_infos, &names, &raw_values, 0..) |field, *name, *raw, i| {
         if (field.type != u32 and field.type != i32 and field.type != f64) continue;
-        enumFields[i] = .{ .name = field.name, .value = i };
+        name.* = field.name;
+        raw.* = i;
         count += 1;
     }
 
-    var decls = [_]std.builtin.Type.Declaration{};
-    break :key @Type(.{
-        .@"enum" = .{
-            .tag_type = std.math.IntFittingRange(0, count - 1),
-            .fields = enumFields[0..count],
-            .decls = &decls,
-            .is_exhaustive = true,
-        },
-    });
+    const TagInt = std.math.IntFittingRange(0, count - 1);
+    var values: [count]TagInt = undefined;
+    for (raw_values, &values) |raw, *v| v.* = raw;
+
+    break :key @Enum(TagInt, .exhaustive, names[0..count], &values);
 };
 
 // NOTE: This is purposely not pub because we want to force outside callers
diff --git a/src/font/SharedGrid.zig b/src/font/SharedGrid.zig
index 18870aaba..92cf05008 100644
--- a/src/font/SharedGrid.zig
+++ b/src/font/SharedGrid.zig
@@ -34,6 +34,7 @@ const Metrics = font.Metrics;
 const Presentation = font.Presentation;
 const Style = font.Style;
 const RenderOptions = font.Glyph.RenderOptions;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.font_shared_grid);
 
@@ -60,7 +61,7 @@ metrics: Metrics,
 /// this directly if they need to i.e. access the atlas directly. Because
 /// callers can use this lock directly, maintainers need to be extra careful
 /// to review call sites to ensure they are using the lock correctly.
-lock: std.Thread.RwLock,
+lock: std.Io.RwLock,
 
 pub const init_tw = tripwire.module(enum {
     codepoints_capacity,
@@ -68,6 +69,8 @@ pub const init_tw = tripwire.module(enum {
     reload_metrics,
 }, init);
 
+pub const InitError = std.mem.Allocator.Error || Collection.UpdateMetricsError;
+
 /// Initialize the grid.
 ///
 /// The resolver must have a collection that supports deferred loading
@@ -80,7 +83,7 @@ pub const init_tw = tripwire.module(enum {
 pub fn init(
     alloc: Allocator,
     resolver: CodepointResolver,
-) !SharedGrid {
+) InitError!SharedGrid {
     const tw = init_tw;
 
     // We need to support loading options since we use the size data
@@ -95,7 +98,7 @@ pub fn init(
         .resolver = resolver,
         .atlas_grayscale = atlas_grayscale,
         .atlas_color = atlas_color,
-        .lock = .{},
+        .lock = .init,
         .metrics = undefined, // Loaded below
     };
 
@@ -162,14 +165,14 @@ pub fn getIndex(
     // Fast path: the cache has the value. This is almost always true and
     // only requires a read lock.
     {
-        self.lock.lockShared();
-        defer self.lock.unlockShared();
+        self.lock.lockSharedUncancelable(global.io());
+        defer self.lock.unlockShared(global.io());
         if (self.codepoints.get(key)) |v| return v;
     }
 
     // Slow path: we need to search this codepoint
-    self.lock.lock();
-    defer self.lock.unlock();
+    self.lock.lockUncancelable(global.io());
+    defer self.lock.unlock(global.io());
 
     // Try to get it, if it is now in the cache another thread beat us to it.
     const gop = try self.codepoints.getOrPut(alloc, key);
@@ -201,8 +204,8 @@ pub fn hasCodepoint(
     cp: u32,
     p: ?Presentation,
 ) bool {
-    self.lock.lockShared();
-    defer self.lock.unlockShared();
+    self.lock.lockSharedUncancelable(global.io());
+    defer self.lock.unlockShared(global.io());
     return self.resolver.collection.hasCodepoint(
         idx,
         cp,
@@ -236,8 +239,8 @@ pub fn renderCodepoint(
 
     // Get the glyph for the font
     const glyph_index = glyph_index: {
-        self.lock.lockShared();
-        defer self.lock.unlockShared();
+        self.lock.lockSharedUncancelable(global.io());
+        defer self.lock.unlockShared(global.io());
         const face = try self.resolver.collection.getFace(index);
         break :glyph_index face.glyphIndex(cp) orelse return null;
     };
@@ -250,6 +253,127 @@ pub const renderGlyph_tw = tripwire.module(enum {
     get_presentation,
 }, renderGlyph);
 
+// FIXME: This gets a massive manual error set for now because there is an
+// equally massive call stack in the get_presentation tracepoint. This should
+// be consolidated into something better ASAP.
+pub const RenderGlyphError = error{
+    ArrayTooLarge,
+    AtlasFull,
+    BadArgument,
+    BbxTooBig,
+    BitmapHandlingError,
+    CMapTableMissing,
+    CannotOpenResource,
+    CannotOpenStream,
+    CannotRenderGlyph,
+    CodeOverflow,
+    CorruptedFontGlyphs,
+    CorruptedFontHeader,
+    CouldNotFindContext,
+    DebugOpCode,
+    DeferredLoadingUnavailable,
+    DivideByZero,
+    ENDFInExecStream,
+    ExecutionTooLong,
+    FontHasNoFile,
+    FontPathCantDecode,
+    FontconfigFailed,
+    FontconfigNoId,
+    FontconfigNoMatch,
+    FontconfigTypeMismatch,
+    GlyphResizeFailed,
+    HarfbuzzFailed,
+    HmtxTableMissing,
+    HorizHeaderMissing,
+    Ignore,
+    IndexOutOfBounds,
+    InvalidArgument,
+    InvalidAtlasFormat,
+    InvalidCacheHandle,
+    InvalidCharMapFormat,
+    InvalidCharMapHandle,
+    InvalidCharacterCode,
+    InvalidCodeRange,
+    InvalidComposite,
+    InvalidDriverHandle,
+    InvalidFaceHandle,
+    InvalidFileFormat,
+    InvalidFrameOperation,
+    InvalidFrameRead,
+    InvalidGlyphFormat,
+    InvalidGlyphIndex,
+    InvalidHandle,
+    InvalidHeight,
+    InvalidHorizMetrics,
+    InvalidLibraryHandle,
+    InvalidMatrix,
+    InvalidOffset,
+    InvalidOpcode,
+    InvalidOutline,
+    InvalidPPem,
+    InvalidPixelSize,
+    InvalidPostTable,
+    InvalidPostTableFormat,
+    InvalidReference,
+    InvalidSVGTable,
+    InvalidSizeHandle,
+    InvalidSlotHandle,
+    InvalidState,
+    InvalidStreamHandle,
+    InvalidStreamOperation,
+    InvalidStreamRead,
+    InvalidStreamSeek,
+    InvalidStreamSkip,
+    InvalidTable,
+    InvalidVersion,
+    InvalidVertMetrics,
+    InvalidWidth,
+    LocationsMissing,
+    LowerModuleVersion,
+    MathError,
+    MissingBbxField,
+    MissingCharsField,
+    MissingEncodingField,
+    MissingFontField,
+    MissingFontboundingboxField,
+    MissingModule,
+    MissingProperty,
+    MissingSizeField,
+    MissingStartcharField,
+    MissingStartfontField,
+    NameTableMissing,
+    NestedDEFS,
+    NestedFrameAccess,
+    NoCurrentPoint,
+    NoUnicodeGlyphName,
+    OutOfMemory,
+    PathNotClosed,
+    PixelSourceNotPreMultiplied,
+    PostTableMissing,
+    RasterCorrupted,
+    RasterNegativeHeight,
+    RasterOverflow,
+    RasterUninitialized,
+    SpecialHasNoFace,
+    StackOverflow,
+    StackUnderflow,
+    Syntax,
+    TableMissing,
+    TooFewArguments,
+    TooManyCaches,
+    TooManyDrivers,
+    TooManyExtensions,
+    TooManyFunctionDefs,
+    TooManyHints,
+    TooManyInstructionDefs,
+    UnimplementedFeature,
+    UnknownFileFormat,
+    UnknownFreetypeError,
+    UnlistedObject,
+    UnsupportedGlyphFormat,
+    WrongAtlas,
+};
+
 /// Render a glyph index. This automatically determines the correct texture
 /// atlas to use and caches the result.
 pub fn renderGlyph(
@@ -258,7 +382,7 @@ pub fn renderGlyph(
     index: Collection.Index,
     glyph_index: u32,
     opts: RenderOptions,
-) !Render {
+) RenderGlyphError!Render {
     const tw = renderGlyph_tw;
 
     const key: GlyphKey = .{ .index = index, .glyph = glyph_index, .opts = opts };
@@ -266,14 +390,14 @@ pub fn renderGlyph(
     // Fast path: the cache has the value. This is almost always true and
     // only requires a read lock.
     {
-        self.lock.lockShared();
-        defer self.lock.unlockShared();
+        self.lock.lockSharedUncancelable(global.io());
+        defer self.lock.unlockShared(global.io());
         if (self.glyphs.get(key)) |v| return v;
     }
 
     // Slow path: we need to search this codepoint
-    self.lock.lock();
-    defer self.lock.unlock();
+    self.lock.lockUncancelable(global.io());
+    defer self.lock.unlock(global.io());
 
     const gop = try self.glyphs.getOrPut(alloc, key);
     if (gop.found_existing) return gop.value_ptr.*;
@@ -468,8 +592,8 @@ test "renderGlyph error after cache insert rolls back cache entry" {
 
     // Get the glyph index for 'A'
     const glyph_index = glyph_index: {
-        grid.lock.lockShared();
-        defer grid.lock.unlockShared();
+        grid.lock.lockSharedUncancelable(testing.io);
+        defer grid.lock.unlockShared(testing.io);
         const face = try grid.resolver.collection.getFace(idx);
         break :glyph_index face.glyphIndex('A').?;
     };
diff --git a/src/font/SharedGridSet.zig b/src/font/SharedGridSet.zig
index 9d8148bdc..b4f602e89 100644
--- a/src/font/SharedGridSet.zig
+++ b/src/font/SharedGridSet.zig
@@ -28,6 +28,7 @@ const SharedGrid = font.SharedGrid;
 const discovery = @import("discovery.zig");
 const configpkg = @import("../config.zig");
 const Config = configpkg.Config;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.font_shared_grid_set);
 
@@ -44,7 +45,7 @@ font_lib: Library,
 font_discover: ?Discover = null,
 
 /// Lock to protect multi-threaded access to the map.
-lock: std.Thread.Mutex = .{},
+lock: std.Io.Mutex = .init,
 
 pub const InitError = Library.InitError;
 
@@ -79,8 +80,8 @@ pub fn deinit(self: *SharedGridSet) void {
 
 /// Returns the number of cached grids.
 pub fn count(self: *SharedGridSet) usize {
-    self.lock.lock();
-    defer self.lock.unlock();
+    self.lock.lockUncancelable(global.io());
+    defer self.lock.unlock(global.io());
     return self.map.count();
 }
 
@@ -100,8 +101,8 @@ pub fn ref(
     var key = try Key.init(self.alloc, config, font_size);
     errdefer key.deinit();
 
-    self.lock.lock();
-    defer self.lock.unlock();
+    self.lock.lockUncancelable(global.io());
+    defer self.lock.unlock(global.io());
 
     const gop = try self.map.getOrPut(self.alloc, key);
     if (gop.found_existing) {
@@ -392,8 +393,8 @@ fn collection(
 /// Decrement the ref count for the given key. If the ref count is zero,
 /// the grid will be deinitialized and removed from the map.j:w
 pub fn deref(self: *SharedGridSet, key: Key) void {
-    self.lock.lock();
-    defer self.lock.unlock();
+    self.lock.lockUncancelable(global.io());
+    defer self.lock.unlock(global.io());
 
     const entry = self.map.getEntry(key) orelse return;
     assert(entry.value_ptr.ref >= 1);
diff --git a/src/font/discovery.zig b/src/font/discovery.zig
index b945aa01b..d1e60fd34 100644
--- a/src/font/discovery.zig
+++ b/src/font/discovery.zig
@@ -12,6 +12,7 @@ const Face = @import("main.zig").Face;
 const Library = @import("main.zig").Library;
 const Presentation = @import("main.zig").Presentation;
 const Variation = @import("main.zig").face.Variation;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.discovery);
 
@@ -942,15 +943,15 @@ pub const Windows = struct {
         desc: Descriptor,
         variations: []const Variation,
         state: State,
-        dir: ?std.fs.Dir,
-        iter: ?std.fs.Dir.Iterator,
+        dir: ?std.Io.Dir,
+        iter: ?std.Io.Dir.Iterator,
         system_path: ?[:0]const u8,
         user_path: ?[:0]const u8,
 
         const State = enum { system, user, done };
 
         pub fn deinit(self: *DiscoverIterator) void {
-            if (self.dir) |*d| d.close();
+            if (self.dir) |*d| d.close(global.io());
             if (self.system_path) |p| self.alloc.free(p);
             if (self.user_path) |p| self.alloc.free(p);
             self.* = undefined;
@@ -967,7 +968,8 @@ pub const Windows = struct {
                                 continue;
                             };
                             self.system_path = path;
-                            self.dir = std.fs.openDirAbsoluteZ(
+                            self.dir = std.Io.Dir.openDirAbsolute(
+                                global.io(),
                                 path,
                                 .{ .iterate = true },
                             ) catch {
@@ -982,7 +984,8 @@ pub const Windows = struct {
                                 continue;
                             };
                             self.user_path = path;
-                            self.dir = std.fs.openDirAbsoluteZ(
+                            self.dir = std.Io.Dir.openDirAbsolute(
+                                global.io(),
                                 path,
                                 .{ .iterate = true },
                             ) catch {
@@ -995,9 +998,9 @@ pub const Windows = struct {
                     }
                 }
 
-                const entry = (self.iter.?.next() catch null) orelse {
+                const entry = (self.iter.?.next(global.io()) catch null) orelse {
                     // Finished this directory; advance state.
-                    if (self.dir) |*d| d.close();
+                    if (self.dir) |*d| d.close(global.io());
                     self.dir = null;
                     self.iter = null;
                     self.state = switch (self.state) {
@@ -1020,7 +1023,7 @@ pub const Windows = struct {
         /// Windows install but we just skip the directory rather than
         /// falling back to a hardcoded drive letter.
         fn systemFontsPath(self: *DiscoverIterator) ?[:0]const u8 {
-            const systemroot = std.process.getEnvVarOwned(
+            const systemroot = global.environ().getAlloc(
                 self.alloc,
                 "SYSTEMROOT",
             ) catch return null;
@@ -1034,7 +1037,7 @@ pub const Windows = struct {
         }
 
         fn userFontsPath(self: *DiscoverIterator) ?[:0]const u8 {
-            const local_appdata = std.process.getEnvVarOwned(
+            const local_appdata = global.environ().getAlloc(
                 self.alloc,
                 "LOCALAPPDATA",
             ) catch return null;
diff --git a/src/font/face/coretext.zig b/src/font/face/coretext.zig
index cd8bc7d8b..4b2af153f 100644
--- a/src/font/face/coretext.zig
+++ b/src/font/face/coretext.zig
@@ -926,6 +926,7 @@ const ColorState = struct {
             const svg = opentype.SVG.init(ptr[0..len]) catch |err| {
                 return switch (err) {
                     error.EndOfStream,
+                    error.ReadFailed,
                     error.SVGVersionNotSupported,
                     => error.InvalidSVGTable,
                 };
diff --git a/src/font/face/freetype.zig b/src/font/face/freetype.zig
index d04fe1809..14a378e5e 100644
--- a/src/font/face/freetype.zig
+++ b/src/font/face/freetype.zig
@@ -18,6 +18,7 @@ const Library = font.Library;
 const opentype = @import("../opentype.zig");
 const quirks = @import("../../quirks.zig");
 const config = @import("../../config.zig");
+const global = @import("../../global.zig");
 
 const F26Dot6 = opentype.sfnt.F26Dot6;
 
@@ -41,7 +42,7 @@ pub const Face = struct {
     ///
     /// This means that anywhere where `self.face.loadGlyph`
     /// is called, this mutex must be held.
-    ft_mutex: *std.Thread.Mutex,
+    ft_mutex: *std.Io.Mutex,
 
     /// Harfbuzz font corresponding to this face.
     hb_font: harfbuzz.Font,
@@ -68,8 +69,8 @@ pub const Face = struct {
         index: i32,
         opts: font.face.Options,
     ) !Face {
-        lib.mutex.lock();
-        defer lib.mutex.unlock();
+        lib.mutex.lockUncancelable(global.io());
+        defer lib.mutex.unlock(global.io());
         const face = try lib.lib.initFace(path, index);
         errdefer face.deinit();
         return try initFace(lib, face, opts);
@@ -81,8 +82,8 @@ pub const Face = struct {
         source: [:0]const u8,
         opts: font.face.Options,
     ) !Face {
-        lib.mutex.lock();
-        defer lib.mutex.unlock();
+        lib.mutex.lockUncancelable(global.io());
+        defer lib.mutex.unlock(global.io());
         const face = try lib.lib.initMemoryFace(source, 0);
         errdefer face.deinit();
         return try initFace(lib, face, opts);
@@ -99,9 +100,9 @@ pub const Face = struct {
         var hb_font = try harfbuzz.freetype.createFont(face.handle);
         errdefer hb_font.destroy();
 
-        const ft_mutex = try lib.alloc.create(std.Thread.Mutex);
+        const ft_mutex = try lib.alloc.create(std.Io.Mutex);
         errdefer lib.alloc.destroy(ft_mutex);
-        ft_mutex.* = .{};
+        ft_mutex.* = .init;
 
         var result: Face = .{
             .lib = lib,
@@ -142,8 +143,8 @@ pub const Face = struct {
     pub fn deinit(self: *Face) void {
         self.lib.alloc.destroy(self.ft_mutex);
         {
-            self.lib.mutex.lock();
-            defer self.lib.mutex.unlock();
+            self.lib.mutex.lockUncancelable(global.io());
+            defer self.lib.mutex.unlock(global.io());
 
             self.face.deinit();
         }
@@ -330,8 +331,8 @@ pub const Face = struct {
 
     /// Returns true if the given glyph ID is colorized.
     pub fn isColorGlyph(self: *const Face, glyph_id: u32) bool {
-        self.ft_mutex.lock();
-        defer self.ft_mutex.unlock();
+        self.ft_mutex.lockUncancelable(global.io());
+        defer self.ft_mutex.unlock(global.io());
 
         // Load the glyph and see what pixel mode it renders with.
         // All modes other than BGRA are non-color.
@@ -429,8 +430,8 @@ pub const Face = struct {
         glyph_index: u32,
         opts: font.Glyph.RenderOptions,
     ) !Glyph {
-        self.ft_mutex.lock();
-        defer self.ft_mutex.unlock();
+        self.ft_mutex.lockUncancelable(global.io());
+        defer self.ft_mutex.unlock(global.io());
 
         // Load the glyph.
         try self.face.loadGlyph(glyph_index, self.glyphLoadFlags(opts.constraint.doesAnything()));
@@ -541,7 +542,7 @@ pub const Face = struct {
                     else
                         0.0;
 
-                const outline = &glyph.*.outline;
+                const outline: *freetype.c.FT_Outline = &glyph.*.outline;
                 for (outline.points[0..@intCast(outline.n_points)]) |*p| {
                     // Convert to f64 for processing
                     var px = f26dot6ToF64(p.x);
@@ -971,8 +972,8 @@ pub const Face = struct {
         // the metrics provided by FreeType, and set ascii_height to null as
         // it's optional.
         const cell_width: f64, const ascii_height: ?f64 = measurements: {
-            self.ft_mutex.lock();
-            defer self.ft_mutex.unlock();
+            self.ft_mutex.lockUncancelable(global.io());
+            defer self.ft_mutex.unlock(global.io());
 
             var max: f64 = 0.0;
             var top: f64 = 0.0;
@@ -1024,8 +1025,8 @@ pub const Face = struct {
 
             break :heights .{
                 cap: {
-                    self.ft_mutex.lock();
-                    defer self.ft_mutex.unlock();
+                    self.ft_mutex.lockUncancelable(global.io());
+                    defer self.ft_mutex.unlock(global.io());
                     if (face.getCharIndex('H')) |glyph_index| {
                         if (face.loadGlyph(glyph_index, self.glyphLoadFlags(false))) {
                             break :cap getGlyphSize(face.handle.*.glyph).height;
@@ -1034,8 +1035,8 @@ pub const Face = struct {
                     break :cap null;
                 },
                 ex: {
-                    self.ft_mutex.lock();
-                    defer self.ft_mutex.unlock();
+                    self.ft_mutex.lockUncancelable(global.io());
+                    defer self.ft_mutex.unlock(global.io());
                     if (face.getCharIndex('x')) |glyph_index| {
                         if (face.loadGlyph(glyph_index, self.glyphLoadFlags(false))) {
                             break :ex getGlyphSize(face.handle.*.glyph).height;
@@ -1048,8 +1049,8 @@ pub const Face = struct {
 
         // Measure "水" (CJK water ideograph, U+6C34) for our ic width.
         const ic_width: ?f64 = ic_width: {
-            self.ft_mutex.lock();
-            defer self.ft_mutex.unlock();
+            self.ft_mutex.lockUncancelable(global.io());
+            defer self.ft_mutex.unlock(global.io());
 
             const glyph = face.getCharIndex('水') orelse break :ic_width null;
 
diff --git a/src/font/glyf_rasterize_png_test.zig b/src/font/glyf_rasterize_png_test.zig
index e8ad70fdf..881c0ed98 100644
--- a/src/font/glyf_rasterize_png_test.zig
+++ b/src/font/glyf_rasterize_png_test.zig
@@ -2,6 +2,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const wuffs = @import("wuffs");
 const z2d = @import("z2d");
+const compat_file = @import("../lib/compat/file.zig");
 
 const glyf_rasterize = @import("glyf_rasterize.zig");
 const glyf = @import("opentype/glyf.zig");
@@ -107,37 +108,38 @@ fn drawCellBoxes(atlas: *z2d.Surface, y: usize, cell_width: usize, cell_height:
 /// `glyf_rasterize_diff.png`, where red is reference-only coverage and green is
 /// newly generated coverage. Returns true when a difference was found.
 fn diffAtlas(
+    io: std.Io,
     alloc: Allocator,
     atlas: *z2d.Surface,
     generated_path: []const u8,
 ) !bool {
     const ref_path = "src/font/testdata/glyf_rasterize.png";
 
-    const generated_file = try std.fs.openFileAbsolute(generated_path, .{ .mode = .read_only });
-    defer generated_file.close();
-    const generated_bytes = try generated_file.readToEndAlloc(alloc, std.math.maxInt(usize));
+    const generated_file = try std.Io.Dir.openFileAbsolute(io, generated_path, .{ .mode = .read_only });
+    defer generated_file.close(io);
+    const generated_bytes = try compat_file.readToEndAlloc(generated_file, alloc, std.math.maxInt(usize));
     defer alloc.free(generated_bytes);
 
-    const cwd_absolute = try std.fs.cwd().realpathAlloc(alloc, ".");
+    const cwd_absolute = try std.Io.Dir.cwd().realPathFileAlloc(io, ".", alloc);
     defer alloc.free(cwd_absolute);
 
-    const ref_file = std.fs.cwd().openFile(ref_path, .{ .mode = .read_only }) catch |err| {
+    const ref_file = std.Io.Dir.cwd().openFile(io, ref_path, .{ .mode = .read_only }) catch |err| {
         log.err("Can't open reference file {s}: {}", .{ ref_path, err });
 
         const test_path = try std.fmt.allocPrint(alloc, "{s}/glyf_rasterize_test.png", .{cwd_absolute});
         defer alloc.free(test_path);
-        try std.fs.copyFileAbsolute(generated_path, test_path, .{});
+        try std.Io.Dir.copyFileAbsolute(generated_path, test_path, io, .{});
         return true;
     };
-    defer ref_file.close();
-    const ref_bytes = try ref_file.readToEndAlloc(alloc, std.math.maxInt(usize));
+    defer ref_file.close(io);
+    const ref_bytes = try compat_file.readToEndAlloc(ref_file, alloc, std.math.maxInt(usize));
     defer alloc.free(ref_bytes);
 
     if (std.mem.eql(u8, generated_bytes, ref_bytes)) return false;
 
     const test_path = try std.fmt.allocPrint(alloc, "{s}/glyf_rasterize_test.png", .{cwd_absolute});
     defer alloc.free(test_path);
-    try std.fs.copyFileAbsolute(generated_path, test_path, .{});
+    try std.Io.Dir.copyFileAbsolute(generated_path, test_path, io, .{});
 
     const ref_rgba = try wuffs.png.decode(alloc, ref_bytes);
     defer alloc.free(ref_rgba.data);
@@ -185,7 +187,7 @@ fn diffAtlas(
     }
 
     const diff_path = "./glyf_rasterize_diff.png";
-    try z2d.png_exporter.writeToPNGFile(diff, diff_path, .{});
+    try z2d.png_exporter.writeToPNGFile(io, diff, diff_path, .{});
     log.err(
         "glyf rasterize visual output differs from reference: test={s}, reference={s}, diff={s}",
         .{ test_path, ref_path, diff_path },
@@ -290,12 +292,12 @@ test "glyf_rasterize: bubbletea glyph protocol examples match reference image" {
 
     var dir = testing.tmpDir(.{});
     defer dir.cleanup();
-    const tmp_dir = try dir.dir.realpathAlloc(alloc, ".");
+    const tmp_dir = try dir.dir.realPathFileAlloc(testing.io, ".", alloc);
     defer alloc.free(tmp_dir);
 
     const generated_path = try std.fmt.allocPrint(alloc, "{s}/glyf_rasterize.png", .{tmp_dir});
     defer alloc.free(generated_path);
-    try z2d.png_exporter.writeToPNGFile(atlas, generated_path, .{});
+    try z2d.png_exporter.writeToPNGFile(testing.io, atlas, generated_path, .{});
 
-    try testing.expect(!try diffAtlas(alloc, &atlas, generated_path));
+    try testing.expect(!try diffAtlas(testing.io, alloc, &atlas, generated_path));
 }
diff --git a/src/font/library.zig b/src/font/library.zig
index 56946343e..49c2e8808 100644
--- a/src/font/library.zig
+++ b/src/font/library.zig
@@ -30,7 +30,7 @@ pub const FreetypeLibrary = struct {
 
     /// Mutex to be held any time the library is
     /// being used to create or destroy a face.
-    mutex: *std.Thread.Mutex,
+    mutex: *std.Io.Mutex,
 
     pub const InitError = freetype.Error || Allocator.Error;
 
@@ -38,8 +38,8 @@ pub const FreetypeLibrary = struct {
         const lib = try freetype.Library.init();
         errdefer lib.deinit();
 
-        const mutex = try alloc.create(std.Thread.Mutex);
-        mutex.* = .{};
+        const mutex = try alloc.create(std.Io.Mutex);
+        mutex.* = .init;
 
         return Library{ .lib = lib, .alloc = alloc, .mutex = mutex };
     }
diff --git a/src/font/opentype/glyf.zig b/src/font/opentype/glyf.zig
index 912b5fe84..d95b7ece7 100644
--- a/src/font/opentype/glyf.zig
+++ b/src/font/opentype/glyf.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
 const sfnt = @import("sfnt.zig");
+const compat_reader = @import("../../lib/compat/reader.zig");
 
 /// Glyph Data Table
 ///
@@ -245,11 +246,10 @@ pub const Glyf = struct {
         ///
         /// The lifetime of this struct, then, is the same as the
         /// lifetime of the data that is used to initialize it.
-        pub fn init(data: []const u8) error{EndOfStream}!Entry {
-            var fbs = std.io.fixedBufferStream(data);
-            const reader = fbs.reader();
-            const header = try reader.readStructEndian(Header, .big);
-            return .{ .header = header, .data = data[fbs.pos..] };
+        pub fn init(data: []const u8) std.Io.Reader.Error!Entry {
+            var reader: std.Io.Reader = .fixed(data);
+            const header = try compat_reader.readStructEndian(&reader, Header, .big);
+            return .{ .header = header, .data = data[@sizeOf(Header)..] };
         }
 
         /// Identifies what type (simple or composite) of entry this is.
@@ -262,10 +262,6 @@ pub const Glyf = struct {
 
         /// Errors that can be returned from `Entry.size()`.
         pub const SizeError = error{
-            /// The entry's data wasn't large enough, ran
-            /// out of bytes before we were done reading.
-            EndOfStream,
-
             /// The entry contains hinting instructions,
             /// which we don't currently support.
             InstructionsNotSupported,
@@ -283,7 +279,7 @@ pub const Glyf = struct {
             /// This entry defines points past the index determined
             /// by the final element of the endPtsOfContours array.
             TooManyPoints,
-        };
+        } || std.Io.Reader.Error;
 
         /// Errors that can be returned from `Entry.decode()`.
         pub const DecodeError = SizeError || Allocator.Error || error{
@@ -299,8 +295,7 @@ pub const Glyf = struct {
         /// NOTE: Currently produces errors when given composite glyphs
         ///       or any glyphs that have hinting instructions included.
         pub fn size(self: Entry) SizeError!usize {
-            var fbs = std.io.fixedBufferStream(self.data);
-            const reader = fbs.reader();
+            var reader: std.Io.Reader = .fixed(self.data);
             switch (self.entryType()) {
                 // https://learn.microsoft.com/en-us/typography/opentype/spec/glyf#simple-glyph-description
                 .simple => {
@@ -329,7 +324,7 @@ pub const Glyf = struct {
                     // of each contour, in increasing numeric order.
                     var max_point_index: isize = -1;
                     for (0..num_contours) |_| {
-                        const index = try reader.readInt(sfnt.uint16, .big);
+                        const index = try compat_reader.readerInt(&reader, sfnt.uint16, .big);
                         // The endpoints are supposed to monotonically increase.
                         if (index <= max_point_index) return error.EndPointsOutOfOrder;
                         max_point_index = index;
@@ -342,7 +337,7 @@ pub const Glyf = struct {
                     // If instructionLength is zero, no instructions
                     // are present for this glyph, and this field is
                     // followed directly by the flags field.
-                    const instructions_length = try reader.readInt(sfnt.uint16, .big);
+                    const instructions_length = try compat_reader.readerInt(&reader, sfnt.uint16, .big);
 
                     // Since we don't have code that validates instruction
                     // byte code, we just reject all glyphs that contain any.
@@ -373,7 +368,7 @@ pub const Glyf = struct {
                     var x_coords_len: usize = 0;
                     var y_coords_len: usize = 0;
                     while (i <= max_point_index) : (i += 1) {
-                        const flag: SimpleFlags = @bitCast(try reader.readByte());
+                        const flag: SimpleFlags = @bitCast(try compat_reader.readByte(&reader));
 
                         // Determine how many bytes the x and y coordinates will
                         // be represented with in the corresponding arrays, add
@@ -393,7 +388,7 @@ pub const Glyf = struct {
                             // that count, and the x_coords_len and y_coords_len
                             // must be increased by the correct number of bytes
                             // as well.
-                            const repeat_count: usize = try reader.readByte();
+                            const repeat_count: usize = try compat_reader.readByte(&reader);
                             i += repeat_count;
                             x_coords_len += repeat_count * flag.xBytes();
                             y_coords_len += repeat_count * flag.yBytes();
@@ -415,7 +410,7 @@ pub const Glyf = struct {
                     // We determined the length of this section (in bytes)
                     // above while processing the flags, so that we can just
                     // skip that many bytes to validate this field.
-                    try reader.skipBytes(x_coords_len, .{});
+                    try compat_reader.readSkipBytes(&reader, x_coords_len);
 
                     // uint8 or int16 yCoordinates[variable]
                     //
@@ -426,7 +421,7 @@ pub const Glyf = struct {
                     // We determined the length of this section (in bytes)
                     // above while processing the flags, so that we can just
                     // skip that many bytes to validate this field.
-                    try reader.skipBytes(y_coords_len, .{});
+                    try compat_reader.readSkipBytes(&reader, y_coords_len);
                 },
 
                 .composite => {
@@ -441,7 +436,7 @@ pub const Glyf = struct {
             }
 
             // No issues found, the glyf entry is valid, return its length.
-            return @sizeOf(Header) + fbs.pos;
+            return @sizeOf(Header) + reader.seek;
         }
 
         /// Decode this simple glyph entry into an owned outline.
@@ -455,8 +450,7 @@ pub const Glyf = struct {
                 .composite => return error.CompositeNotSupported,
             }
 
-            var fbs = std.io.fixedBufferStream(self.data);
-            const reader = fbs.reader();
+            var reader: std.Io.Reader = .fixed(self.data);
 
             // A zero-contour glyph may be header-only. See size for the
             // reason for the hardcoded 2 here.
@@ -473,7 +467,7 @@ pub const Glyf = struct {
             // If we have no contours, then the only possible remaining
             // field is instructionLength. Instructions are not supported.
             if (num_contours == 0) {
-                const instructions_length = try reader.readInt(sfnt.uint16, .big);
+                const instructions_length = try compat_reader.readerInt(&reader, sfnt.uint16, .big);
                 if (instructions_length > 0) return error.InstructionsNotSupported;
                 return .{ .points = &.{}, .contours = end_points };
             }
@@ -488,7 +482,7 @@ pub const Glyf = struct {
                 // with the valid index. The final endpoint tells us our point
                 // count, since endpoints are stored as inclusive point indices.
                 for (0..end_points.len) |i| {
-                    const index = try reader.readInt(sfnt.uint16, .big);
+                    const index = try compat_reader.readerInt(&reader, sfnt.uint16, .big);
                     if (index <= prev_end_point) return error.EndPointsOutOfOrder;
                     prev_end_point = index;
                     end_points[i] = index;
@@ -499,7 +493,7 @@ pub const Glyf = struct {
             };
 
             // Instructions are not supported.
-            const instructions_length = try reader.readInt(sfnt.uint16, .big);
+            const instructions_length = try compat_reader.readerInt(&reader, sfnt.uint16, .big);
             if (instructions_length > 0) return error.InstructionsNotSupported;
 
             // Allocate our points right away even though the next entries
@@ -522,12 +516,12 @@ pub const Glyf = struct {
             {
                 var point_i: usize = 0;
                 while (point_i < point_count) {
-                    const flag: SimpleFlags = @bitCast(try reader.readByte());
+                    const flag: SimpleFlags = @bitCast(try compat_reader.readByte(&reader));
                     flags[point_i] = flag;
                     point_i += 1;
 
                     if (flag.repeat) {
-                        const repeat_count: usize = try reader.readByte();
+                        const repeat_count: usize = try compat_reader.readByte(&reader);
                         if (point_i + repeat_count > point_count) return error.TooManyPoints;
 
                         for (0..repeat_count) |_| {
@@ -543,11 +537,11 @@ pub const Glyf = struct {
             for (flags, points) |flag, *point| {
                 const dx: i32 = if (flag.x_short) short: {
                     break :short if (flag.x_repeat_or_sign)
-                        @as(i32, try reader.readByte())
+                        @as(i32, try compat_reader.readByte(&reader))
                     else
-                        -@as(i32, try reader.readByte());
+                        -@as(i32, try compat_reader.readByte(&reader));
                 } else if (!flag.x_repeat_or_sign)
-                    @as(i32, try reader.readInt(sfnt.int16, .big))
+                    @as(i32, try compat_reader.readerInt(&reader, sfnt.int16, .big))
                 else
                     0;
 
@@ -564,11 +558,11 @@ pub const Glyf = struct {
             for (flags, points) |flag, *point| {
                 const dy: i32 = if (flag.y_short) short: {
                     break :short if (flag.y_repeat_or_sign)
-                        @as(i32, try reader.readByte())
+                        @as(i32, try compat_reader.readByte(&reader))
                     else
-                        -@as(i32, try reader.readByte());
+                        -@as(i32, try compat_reader.readByte(&reader));
                 } else if (!flag.y_repeat_or_sign)
-                    @as(i32, try reader.readInt(sfnt.int16, .big))
+                    @as(i32, try compat_reader.readerInt(&reader, sfnt.int16, .big))
                 else
                     0;
 
@@ -599,7 +593,7 @@ pub const Glyf = struct {
     }
 
     /// Retrieve the entry at the provided offset.
-    pub fn entry(self: Glyf, index: usize) error{EndOfStream}!Entry {
+    pub fn entry(self: Glyf, index: usize) std.Io.Reader.Error!Entry {
         return try Entry.init(self.data[index..]);
     }
 };
diff --git a/src/font/opentype/head.zig b/src/font/opentype/head.zig
index 38284d9cf..009fd1448 100644
--- a/src/font/opentype/head.zig
+++ b/src/font/opentype/head.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const sfnt = @import("sfnt.zig");
+const compat_reader = @import("../../lib/compat/reader.zig");
 
 /// Font Header Table
 ///
@@ -134,10 +135,9 @@ pub const Head = extern struct {
     glyphDataFormat: sfnt.int16 align(1),
 
     /// Parse the table from raw data.
-    pub fn init(data: []const u8) error{EndOfStream}!Head {
-        var fbs = std.io.fixedBufferStream(data);
-        const reader = fbs.reader();
-        return try reader.readStructEndian(Head, .big);
+    pub fn init(data: []const u8) std.Io.Reader.Error!Head {
+        var reader: std.Io.Reader = .fixed(data);
+        return try compat_reader.readStructEndian(&reader, Head, .big);
     }
 };
 
diff --git a/src/font/opentype/hhea.zig b/src/font/opentype/hhea.zig
index b2b3f3e20..7ad77054c 100644
--- a/src/font/opentype/hhea.zig
+++ b/src/font/opentype/hhea.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const sfnt = @import("sfnt.zig");
+const compat_reader = @import("../../lib/compat/reader.zig");
 
 /// Horizontal Header Table
 ///
@@ -71,10 +72,8 @@ pub const Hhea = extern struct {
 
     /// Parse the table from raw data.
     pub fn init(data: []const u8) !Hhea {
-        var fbs = std.io.fixedBufferStream(data);
-        const reader = fbs.reader();
-
-        return try reader.readStructEndian(Hhea, .big);
+        var reader: std.Io.Reader = .fixed(data);
+        return try compat_reader.readStructEndian(&reader, Hhea, .big);
     }
 };
 
diff --git a/src/font/opentype/os2.zig b/src/font/opentype/os2.zig
index 1cd11f35e..5bb0b42be 100644
--- a/src/font/opentype/os2.zig
+++ b/src/font/opentype/os2.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const sfnt = @import("sfnt.zig");
+const compat_reader = @import("../../lib/compat/reader.zig");
 
 pub const FSSelection = packed struct(sfnt.uint16) {
     /// Font contains italic or oblique glyphs, otherwise they are upright.
@@ -348,21 +349,17 @@ pub const OS2 = struct {
     usUpperOpticalPointSize: ?u16 = null,
 
     /// Parse the table from raw data.
-    pub fn init(data: []const u8) error{
-        EndOfStream,
-        OS2VersionNotSupported,
-    }!OS2 {
-        var fbs = std.io.fixedBufferStream(data);
-        const reader = fbs.reader();
+    pub fn init(data: []const u8) (error{OS2VersionNotSupported} || std.Io.Reader.Error)!OS2 {
+        var reader: std.Io.Reader = .fixed(data);
 
-        const version = try reader.readInt(sfnt.uint16, .big);
+        const version = try compat_reader.readerInt(&reader, sfnt.uint16, .big);
 
         // Return to the start, cause the version is part of the struct.
-        try fbs.seekTo(0);
+        reader.seek = 0;
 
         switch (version) {
             5 => {
-                const table = try reader.readStructEndian(OS2v5, .big);
+                const table = try compat_reader.readStructEndian(&reader, OS2v5, .big);
                 return .{
                     .version = table.version,
                     .xAvgCharWidth = table.xAvgCharWidth,
@@ -406,7 +403,7 @@ pub const OS2 = struct {
                 };
             },
             4, 3, 2 => {
-                const table = try reader.readStructEndian(OS2v4_3_2, .big);
+                const table = try compat_reader.readStructEndian(&reader, OS2v4_3_2, .big);
                 return .{
                     .version = table.version,
                     .xAvgCharWidth = table.xAvgCharWidth,
@@ -448,7 +445,7 @@ pub const OS2 = struct {
                 };
             },
             1 => {
-                const table = try reader.readStructEndian(OS2v1, .big);
+                const table = try compat_reader.readStructEndian(&reader, OS2v1, .big);
                 return .{
                     .version = table.version,
                     .xAvgCharWidth = table.xAvgCharWidth,
@@ -485,7 +482,7 @@ pub const OS2 = struct {
                 };
             },
             0 => {
-                const table = try reader.readStructEndian(OS2v0, .big);
+                const table = try compat_reader.readStructEndian(&reader, OS2v0, .big);
                 return .{
                     .version = table.version,
                     .xAvgCharWidth = table.xAvgCharWidth,
diff --git a/src/font/opentype/post.zig b/src/font/opentype/post.zig
index 8031a0a4d..776bf8a36 100644
--- a/src/font/opentype/post.zig
+++ b/src/font/opentype/post.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const sfnt = @import("sfnt.zig");
+const compat_reader = @import("../../lib/compat/reader.zig");
 
 /// PostScript Table
 ///
@@ -46,10 +47,9 @@ pub const Post = extern struct {
     maxMemType1: sfnt.uint32 align(1),
 
     /// Parse the table from raw data.
-    pub fn init(data: []const u8) error{EndOfStream}!Post {
-        var fbs = std.io.fixedBufferStream(data);
-        const reader = fbs.reader();
-        return try reader.readStructEndian(Post, .big);
+    pub fn init(data: []const u8) std.Io.Reader.Error!Post {
+        var reader: std.Io.Reader = .fixed(data);
+        return try compat_reader.readStructEndian(&reader, Post, .big);
     }
 };
 
diff --git a/src/font/opentype/sfnt.zig b/src/font/opentype/sfnt.zig
index 55a9a0bdf..8b182e696 100644
--- a/src/font/opentype/sfnt.zig
+++ b/src/font/opentype/sfnt.zig
@@ -235,8 +235,7 @@ pub const SFNT = struct {
     /// Parse a font from raw data. The struct will keep a
     /// reference to `data` and use it for future operations.
     pub fn init(data: []const u8, alloc: Allocator) !SFNT {
-        var fbs = std.io.fixedBufferStream(data);
-        const reader = fbs.reader();
+        var reader: std.Io.Reader = .fixed(data);
 
         // SFNT files use big endian, if our native endian is
         // not big we'll need to byte swap the values we read.
@@ -244,7 +243,7 @@ pub const SFNT = struct {
 
         var directory: Directory = undefined;
 
-        try reader.readNoEof(std.mem.asBytes(&directory.offset));
+        try reader.readSliceAll(std.mem.asBytes(&directory.offset));
         if (byte_swap) std.mem.byteSwapAllFields(
             Directory.OffsetSubtable,
             &directory.offset,
@@ -252,7 +251,7 @@ pub const SFNT = struct {
 
         directory.records = try alloc.alloc(Directory.TableRecord, directory.offset.num_tables);
 
-        try reader.readNoEof(std.mem.sliceAsBytes(directory.records));
+        try reader.readSliceAll(std.mem.sliceAsBytes(directory.records));
         if (byte_swap) for (directory.records) |*record| {
             std.mem.byteSwapAllFields(
                 Directory.TableRecord,
diff --git a/src/font/opentype/svg.zig b/src/font/opentype/svg.zig
index b4d9ccaa2..9115fe62f 100644
--- a/src/font/opentype/svg.zig
+++ b/src/font/opentype/svg.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const font = @import("../main.zig");
+const compat_reader = @import("../../lib/compat/reader.zig");
 
 /// SVG glyphs description table.
 ///
@@ -21,27 +22,24 @@ pub const SVG = struct {
     /// All records in the table.
     records: []const [12]u8,
 
-    pub fn init(data: []const u8) error{
-        EndOfStream,
-        SVGVersionNotSupported,
-    }!SVG {
-        var fbs = std.io.fixedBufferStream(data);
-        const reader = fbs.reader();
+    pub fn init(data: []const u8) (error{SVGVersionNotSupported} || std.Io.Reader.Error)!SVG {
+        var reader: std.Io.Reader = .fixed(data);
 
         // Version
-        if (try reader.readInt(u16, .big) != 0) {
+        if (try compat_reader.readerInt(&reader, u16, .big) != 0) {
             return error.SVGVersionNotSupported;
         }
 
         // Offset
-        const offset = try reader.readInt(u32, .big);
+        const offset = try compat_reader.readerInt(&reader, u32, .big);
 
         // Seek to the offset to get our document list
-        try fbs.seekTo(offset);
+        if (offset > data.len) return error.EndOfStream;
+        reader.seek = offset;
 
         // Get our document records along with the start/end glyph range.
-        const len = try reader.readInt(u16, .big);
-        const records: [*]const [12]u8 = @ptrCast(data[try fbs.getPos()..]);
+        const len = try compat_reader.readerInt(&reader, u16, .big);
+        const records: [*]const [12]u8 = @ptrCast(data[reader.seek..]);
         const start_range = try glyphRange(&records[0]);
         const end_range = if (len == 1) start_range else try glyphRange(&records[(len - 1)]);
 
@@ -84,11 +82,10 @@ pub const SVG = struct {
     }
 
     fn glyphRange(record: []const u8) !struct { u16, u16 } {
-        var fbs = std.io.fixedBufferStream(record);
-        const reader = fbs.reader();
+        var reader: std.Io.Reader = .fixed(record);
         return .{
-            try reader.readInt(u16, .big),
-            try reader.readInt(u16, .big),
+            try compat_reader.readerInt(&reader, u16, .big),
+            try compat_reader.readerInt(&reader, u16, .big),
         };
     }
 };
@@ -112,3 +109,13 @@ test "SVG" {
     try testing.expectEqual(11482, svg.end_glyph_id);
     try testing.expect(svg.hasGlyph(11482));
 }
+
+test "SVG document list offset past end" {
+    const testing = std.testing;
+    const table = [_]u8{
+        0, 0, // Version
+        0, 0, 0, 7, // Document list offset, one byte past end
+    };
+
+    try testing.expectError(error.EndOfStream, SVG.init(&table));
+}
diff --git a/src/font/shaper/coretext.zig b/src/font/shaper/coretext.zig
index 8a9374bd6..27da357a7 100644
--- a/src/font/shaper/coretext.zig
+++ b/src/font/shaper/coretext.zig
@@ -20,6 +20,7 @@ const SharedGrid = font.SharedGrid;
 const Style = font.Style;
 const Presentation = font.Presentation;
 const CFReleaseThread = os.CFReleaseThread;
+const global = @import("../../global.zig");
 
 const log = std.log.scoped(.font_shaper);
 
@@ -90,7 +91,7 @@ pub const Shaper = struct {
         unichars: std.ArrayListUnmanaged(u16),
 
         fn init() RunState {
-            return .{ .codepoints = .{}, .unichars = .{} };
+            return .{ .codepoints = .empty, .unichars = .empty };
         }
 
         fn deinit(self: *RunState, alloc: Allocator) void {
@@ -213,18 +214,18 @@ pub const Shaper = struct {
             CFReleaseThread.threadMain,
             .{cf_release_thread},
         );
-        cf_release_thr.setName("cf_release") catch {};
+        cf_release_thr.setName(global.io(), "cf_release") catch {};
 
         return .{
             .alloc = alloc,
-            .cell_buf = .{},
+            .cell_buf = .empty,
             .run_state = run_state,
             .features = features,
             .features_no_default = features_no_default,
             .typesetter_attr_dict = typesetter_attr_dict,
-            .cached_fonts = .{},
+            .cached_fonts = .empty,
             .cached_font_grid = 0,
-            .cf_release_pool = .{},
+            .cf_release_pool = .empty,
             .cf_release_thread = cf_release_thread,
             .cf_release_thr = cf_release_thr,
         };
@@ -282,7 +283,7 @@ pub const Shaper = struct {
         // Send the items. If the send succeeds then we wake up the
         // thread to process the items. If the send fails then do a manual
         // cleanup.
-        if (self.cf_release_thread.mailbox.push(.{ .release = .{
+        if (self.cf_release_thread.mailbox.push(global.io(), .{ .release = .{
             .refs = items,
             .alloc = self.alloc,
         } }, .{ .forever = {} }) != 0) {
@@ -606,8 +607,8 @@ pub const Shaper = struct {
             //
             // Because of this, we only acquire the read lock to grab the
             // face and set it up, then release it.
-            grid.lock.lockShared();
-            defer grid.lock.unlockShared();
+            grid.lock.lockSharedUncancelable(global.io());
+            defer grid.lock.unlockShared(global.io());
 
             const face = try grid.resolver.collection.getFace(index);
             const original = face.font;
@@ -842,7 +843,7 @@ test "run iterator" {
     defer testdata.deinit();
 
     {
-        var t: terminal.Terminal = try .init(alloc, .{
+        var t: terminal.Terminal = try .init(testing.io, alloc, .{
             .cols = 5,
             .rows = 3,
         });
@@ -869,7 +870,7 @@ test "run iterator" {
 
     // Spaces should be part of a run
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -892,7 +893,7 @@ test "run iterator" {
 
     {
         // Make a screen with some data
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -917,7 +918,7 @@ test "run iterator" {
     // Bad ligatures
     for (&[_][]const u8{ "fl", "fi", "st" }) |bad| {
         // Make a screen with some data
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -949,7 +950,7 @@ test "run iterator: empty cells with background set" {
 
     {
         // Make a screen with some data
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1009,7 +1010,7 @@ test "shape" {
     buf_idx += try std.unicode.utf8Encode(0x1F3FD, buf[buf_idx..]); // Medium skin tone
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1048,7 +1049,7 @@ test "shape nerd fonts" {
     buf_idx += try std.unicode.utf8Encode(' ', buf[buf_idx..]); // space
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1081,7 +1082,7 @@ test "shape inconsolata ligs" {
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1110,7 +1111,7 @@ test "shape inconsolata ligs" {
     }
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1147,7 +1148,7 @@ test "shape monaspace ligs" {
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1185,7 +1186,7 @@ test "shape left-replaced lig in last run" {
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1223,7 +1224,7 @@ test "shape left-replaced lig in early run" {
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1258,7 +1259,7 @@ test "shape U+3C9 with JB Mono" {
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1295,7 +1296,7 @@ test "shape emoji width" {
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1330,7 +1331,7 @@ test "shape emoji width long" {
     defer testdata.deinit();
 
     // Make a screen and add a long emoji sequence to it.
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     var page = t.screens.active.pages.pages.first.?.page();
@@ -1338,7 +1339,7 @@ test "shape emoji width long" {
     const cell = &row.cells.ptr(page.memory)[0];
     cell.* = .{
         .content_tag = .codepoint,
-        .content = .{ .codepoint = 0x1F9D4 }, // Person with beard
+        .content = .{ .codepoint = .{ .data = 0x1F9D4 } }, // Person with beard
     };
     var graphemes = [_]u21{
         0x1F3FB, // Light skin tone (Fitz 1-2)
@@ -1385,7 +1386,7 @@ test "shape variation selector VS15" {
     buf_idx += try std.unicode.utf8Encode(0xFE0E, buf[buf_idx..]); // ZWJ to force text
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1424,7 +1425,7 @@ test "shape variation selector VS16" {
     buf_idx += try std.unicode.utf8Encode(0xFE0F, buf[buf_idx..]); // ZWJ to force color
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1458,7 +1459,7 @@ test "shape with empty cells in between" {
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1502,7 +1503,7 @@ test "shape Combining characters" {
     buf_idx += try std.unicode.utf8Encode('a', buf[buf_idx..]);
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1552,7 +1553,7 @@ test "shape Devanagari string" {
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Disable grapheme clustering
@@ -1611,7 +1612,7 @@ test "shape Tai Tham vowels (position differs from advance)" {
     buf_idx += try std.unicode.utf8Encode(0x1a70, buf[buf_idx..]); //  ᩰ
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1672,7 +1673,7 @@ test "shape Tai Tham letters (position.y differs from advance)" {
     buf_idx += try std.unicode.utf8Encode(0x1a69, buf[buf_idx..]); // U
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1732,7 +1733,7 @@ test "shape Javanese ligatures" {
     buf_idx += try std.unicode.utf8Encode(0xa9b8, buf[buf_idx..]); // Vowel sign SUKU
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1795,7 +1796,7 @@ test "shape Chakma vowel sign with ligature (vowel sign renders first)" {
     buf_idx += try std.unicode.utf8Encode(0x1112c, buf[buf_idx..]); // Vowel Sign U
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1866,7 +1867,7 @@ test "shape Bengali ligatures with out of order vowels" {
     buf_idx += try std.unicode.utf8Encode(0x09c7, buf[buf_idx..]); // Vowel sign E
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1924,7 +1925,7 @@ test "shape box glyphs" {
     buf_idx += try std.unicode.utf8Encode(0x2501, buf[buf_idx..]); //
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1962,7 +1963,7 @@ test "shape selection boundary" {
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -2067,7 +2068,7 @@ test "shape cursor boundary" {
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -2204,7 +2205,7 @@ test "shape cursor boundary and colored emoji" {
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 3, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -2301,7 +2302,7 @@ test "shape cell attribute change" {
 
     // Plain >= should shape into 1 run
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -2327,7 +2328,7 @@ test "shape cell attribute change" {
 
     // Bold vs regular should split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -2355,7 +2356,7 @@ test "shape cell attribute change" {
 
     // Changing fg color should split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -2386,7 +2387,7 @@ test "shape cell attribute change" {
 
     // Changing bg color should NOT split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -2417,7 +2418,7 @@ test "shape cell attribute change" {
 
     // Same bg color should not split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -2462,7 +2463,7 @@ test "shape high plane sprite font codepoint" {
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(testing.io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
diff --git a/src/font/shaper/feature.zig b/src/font/shaper/feature.zig
index 5bd73f97f..c60eb049f 100644
--- a/src/font/shaper/feature.zig
+++ b/src/font/shaper/feature.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const assert = @import("../../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
+const compat_reader = @import("../../lib/compat/reader.zig");
 
 const log = std.log.scoped(.font_shaper);
 
@@ -18,9 +19,8 @@ pub const Feature = struct {
     value: u32,
 
     pub fn fromString(str: []const u8) ?Feature {
-        var fbs = std.io.fixedBufferStream(str);
-        const reader = fbs.reader();
-        return .fromReader(reader);
+        var reader: std.Io.Reader = .fixed(str);
+        return .fromReader(&reader);
     }
 
     /// Parse a single font feature setting from a std.io.Reader, with a version
@@ -55,7 +55,7 @@ pub const Feature = struct {
             done,
         }).start) {
             // If we're done then we skip whitespace until we see a ','.
-            .done => while (true) switch (reader.readByte() catch ',') {
+            .done => while (true) switch (compat_reader.readByte(reader) catch ',') {
                 ' ', '\t' => continue,
                 ',' => break,
                 // If we see something other than whitespace or a ','
@@ -66,11 +66,11 @@ pub const Feature = struct {
             // If we're fast-forwarding from an error we just wanna
             // stop at the first boundary and ignore all other bytes.
             .err => {
-                reader.skipUntilDelimiterOrEof(',') catch {};
+                compat_reader.readSkipUntilDelimiterOrEof(reader, ',') catch {};
                 return null;
             },
 
-            .start => while (true) switch (reader.readByte() catch ',') {
+            .start => while (true) switch (compat_reader.readByte(reader) catch ',') {
                 // Ignore leading whitespace.
                 ' ', '\t' => continue,
                 // Empty feature string.
@@ -97,7 +97,7 @@ pub const Feature = struct {
                 },
             },
 
-            .tag => while (true) switch (reader.readByte() catch ',') {
+            .tag => while (true) switch (compat_reader.readByte(reader) catch ',') {
                 // If the tag is interrupted by a comma it's invalid.
                 ',' => return null,
                 // Ignore quote marks. This does technically ignore cases like
@@ -112,7 +112,7 @@ pub const Feature = struct {
                 },
             },
 
-            .space => while (true) switch (reader.readByte() catch ',') {
+            .space => while (true) switch (compat_reader.readByte(reader) catch ',') {
                 ' ', '\t' => continue,
                 // Ignore quote marks since we might have a
                 // closing quote from the tag still ahead.
@@ -142,7 +142,7 @@ pub const Feature = struct {
                 else => continue :state .err,
             },
 
-            .int => while (true) switch (reader.readByte() catch ',') {
+            .int => while (true) switch (compat_reader.readByte(reader) catch ',') {
                 ',' => break,
                 '0'...'9' => |byte| {
                     // If our value gets too big while
@@ -155,7 +155,7 @@ pub const Feature = struct {
                 else => continue :state .err,
             },
 
-            .bool => while (true) switch (reader.readByte() catch ',') {
+            .bool => while (true) switch (compat_reader.readByte(reader) catch ',') {
                 ',' => return null,
                 'n', 'N' => {
                     // "ofn"
@@ -222,7 +222,7 @@ pub const Feature = struct {
 
 /// A list of font feature settings (see `Feature` for more documentation).
 pub const FeatureList = struct {
-    features: std.ArrayListUnmanaged(Feature) = .{},
+    features: std.ArrayList(Feature) = .empty,
 
     pub fn deinit(self: *FeatureList, alloc: Allocator) void {
         self.features.deinit(alloc);
@@ -243,15 +243,14 @@ pub const FeatureList = struct {
         alloc: Allocator,
         str: []const u8,
     ) !void {
-        var fbs = std.io.fixedBufferStream(str);
-        const reader = fbs.reader();
-        while (fbs.pos < fbs.buffer.len) {
-            const i = fbs.pos;
-            if (Feature.fromReader(reader)) |feature| {
+        var reader: std.Io.Reader = .fixed(str);
+        while (reader.seek < reader.end) {
+            const i = reader.seek;
+            if (Feature.fromReader(&reader)) |feature| {
                 try self.features.append(alloc, feature);
             } else log.warn(
                 "failed to parse font feature setting: \"{s}\"",
-                .{fbs.buffer[i..fbs.pos]},
+                .{reader.buffer[i..reader.seek]},
             );
         }
     }
diff --git a/src/font/shaper/harfbuzz.zig b/src/font/shaper/harfbuzz.zig
index 996aabff0..f83b51722 100644
--- a/src/font/shaper/harfbuzz.zig
+++ b/src/font/shaper/harfbuzz.zig
@@ -15,6 +15,7 @@ const Library = font.Library;
 const SharedGrid = font.SharedGrid;
 const Style = font.Style;
 const Presentation = font.Presentation;
+const global = @import("../../global.zig");
 
 const log = std.log.scoped(.font_shaper);
 
@@ -36,7 +37,7 @@ pub const Shaper = struct {
     /// The codepoints added to the buffer before shaping. We need to keep
     /// these separately because after shaping, HarfBuzz replaces codepoints
     /// with glyph indices in the buffer.
-    codepoints: std.ArrayListUnmanaged(Codepoint) = .{},
+    codepoints: std.ArrayList(Codepoint) = .empty,
 
     const Codepoint = struct {
         cluster: u32,
@@ -87,7 +88,7 @@ pub const Shaper = struct {
         return Shaper{
             .alloc = alloc,
             .hb_buf = try harfbuzz.Buffer.create(),
-            .cell_buf = .{},
+            .cell_buf = .empty,
             .hb_feats = hb_feats,
         };
     }
@@ -134,8 +135,8 @@ pub const Shaper = struct {
             // We have to lock the grid to get the face and unfortunately
             // freetype faces (typically used with harfbuzz) are not thread
             // safe so this has to be an exclusive lock.
-            run.grid.lock.lock();
-            defer run.grid.lock.unlock();
+            run.grid.lock.lockUncancelable(global.io());
+            defer run.grid.lock.unlock(global.io());
 
             const face = try run.grid.resolver.collection.getFace(run.font_index);
             const i = if (!face.quirks_disable_default_font_features) 0 else i: {
@@ -437,13 +438,14 @@ pub const Shaper = struct {
 test "run iterator" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     {
         // Make a screen with some data
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -467,7 +469,7 @@ test "run iterator" {
 
     // Spaces should be part of a run
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -490,7 +492,7 @@ test "run iterator" {
 
     {
         // Make a screen with some data
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -521,13 +523,14 @@ test "run iterator" {
 test "run iterator: empty cells with background set" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     {
         // Make a screen with some data
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -576,6 +579,7 @@ test "run iterator: empty cells with background set" {
 test "shape" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
@@ -587,7 +591,7 @@ test "shape" {
     buf_idx += try std.unicode.utf8Encode(0x1F3FD, buf[buf_idx..]); // Medium skin tone
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -616,12 +620,13 @@ test "shape" {
 test "shape inconsolata ligs" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -650,7 +655,7 @@ test "shape inconsolata ligs" {
     }
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -682,12 +687,13 @@ test "shape inconsolata ligs" {
 test "shape monaspace ligs" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaperWithFont(alloc, .monaspace_neon);
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -723,11 +729,12 @@ test "shape monaspace ligs" {
 test "shape arabic forced LTR" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaperWithFont(alloc, .arabic);
     defer testdata.deinit();
 
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 120, .rows = 30 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 120, .rows = 30 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -763,12 +770,13 @@ test "shape arabic forced LTR" {
 test "shape emoji width" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 5, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 5, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -800,12 +808,14 @@ test "shape emoji width" {
 test "shape emoji width long" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     // Make a screen and add a long emoji sequence to it.
     var t = try terminal.Terminal.init(
+        io,
         alloc,
         .{ .cols = 30, .rows = 3 },
     );
@@ -816,7 +826,7 @@ test "shape emoji width long" {
     const cell = &row.cells.ptr(page.memory)[0];
     cell.* = .{
         .content_tag = .codepoint,
-        .content = .{ .codepoint = 0x1F9D4 }, // Person with beard
+        .content = .{ .codepoint = @bitCast(@as(u24, 0x1F9D4)) }, // Person with beard
     };
     var graphemes = [_]u21{
         0x1F3FB, // Light skin tone (Fitz 1-2)
@@ -855,6 +865,7 @@ test "shape emoji width long" {
 test "shape variation selector VS15" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
@@ -865,7 +876,7 @@ test "shape variation selector VS15" {
     buf_idx += try std.unicode.utf8Encode(0xFE0E, buf[buf_idx..]); // ZWJ to force text
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -896,6 +907,7 @@ test "shape variation selector VS15" {
 test "shape variation selector VS16" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
@@ -906,7 +918,7 @@ test "shape variation selector VS16" {
     buf_idx += try std.unicode.utf8Encode(0xFE0F, buf[buf_idx..]); // ZWJ to force color
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -937,12 +949,14 @@ test "shape variation selector VS16" {
 test "shape with empty cells in between" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     // Make a screen with some data
     var t = try terminal.Terminal.init(
+        io,
         alloc,
         .{ .cols = 30, .rows = 3 },
     );
@@ -977,6 +991,7 @@ test "shape with empty cells in between" {
 test "shape Combining characters" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
@@ -990,6 +1005,7 @@ test "shape Combining characters" {
 
     // Make a screen with some data
     var t = try terminal.Terminal.init(
+        io,
         alloc,
         .{ .cols = 30, .rows = 3 },
     );
@@ -1029,6 +1045,7 @@ test "shape Combining characters" {
 test "shape Devanagari string" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // We need a font that supports devanagari for this to work, if we can't
     // find Arial Unicode MS, which is a system font on macOS, we just skip
@@ -1040,7 +1057,7 @@ test "shape Devanagari string" {
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Disable grapheme clustering
@@ -1087,6 +1104,7 @@ test "shape Tai Tham vowels (position differs from advance)" {
     // // behavior.
     // const testing = std.testing;
     // const alloc = testing.allocator;
+    // const io = testing.io;
 
     // // We need a font that supports Tai Tham for this to work, if we can't find
     // // Noto Sans Tai Tham, which is a system font on macOS, we just skip the
@@ -1103,7 +1121,7 @@ test "shape Tai Tham vowels (position differs from advance)" {
     // buf_idx += try std.unicode.utf8Encode(0x1a70, buf[buf_idx..]); //  ᩰ
 
     // // Make a screen with some data
-    // var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    // var t = try terminal.Terminal.init(io, alloc, .{ .cols = 30, .rows = 3 });
     // defer t.deinit(alloc);
 
     // // Enable grapheme clustering
@@ -1147,6 +1165,7 @@ test "shape Tai Tham vowels (position differs from advance)" {
 test "shape Tibetan characters" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // We need a font that has multiple glyphs for this codepoint to reproduce
     // the old broken behavior, and Noto Serif Tibetan is one of them. It's not
@@ -1162,7 +1181,7 @@ test "shape Tibetan characters" {
     buf_idx += try std.unicode.utf8Encode(0x0f00, buf[buf_idx..]); // ༀ
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1203,6 +1222,7 @@ test "shape Tai Tham letters (run_offset.y differs from zero)" {
     return error.SkipZigTest;
     // const testing = std.testing;
     // const alloc = testing.allocator;
+    // const io = testing.io;
 
     // // We need a font that supports Tai Tham for this to work, if we can't find
     // // Noto Sans Tai Tham, which is a system font on macOS, we just skip the
@@ -1224,7 +1244,7 @@ test "shape Tai Tham letters (run_offset.y differs from zero)" {
     // buf_idx += try std.unicode.utf8Encode(0x1a69, buf[buf_idx..]); // U
 
     // // Make a screen with some data
-    // var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    // var t = try terminal.Terminal.init(io, alloc, .{ .cols = 30, .rows = 3 });
     // defer t.deinit(alloc);
 
     // // Enable grapheme clustering
@@ -1266,6 +1286,7 @@ test "shape Javanese ligatures" {
     return error.SkipZigTest;
     // const testing = std.testing;
     // const alloc = testing.allocator;
+    // const io = testing.io;
 
     // // We need a font that supports Javanese for this to work, if we can't find
     // // Noto Sans Javanese Regular, which is a system font on macOS, we just
@@ -1287,7 +1308,7 @@ test "shape Javanese ligatures" {
     // buf_idx += try std.unicode.utf8Encode(0xa9b8, buf[buf_idx..]); // Vowel sign SUKU
 
     // // Make a screen with some data
-    // var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    // var t = try terminal.Terminal.init(io, alloc, .{ .cols = 30, .rows = 3 });
     // defer t.deinit(alloc);
 
     // // Enable grapheme clustering
@@ -1327,6 +1348,7 @@ test "shape Javanese ligatures" {
 test "shape Chakma vowel sign with ligature (vowel sign renders first)" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // We need a font that supports Chakma for this to work, if we can't find
     // Noto Sans Chakma Regular, which is a system font on macOS, we just skip
@@ -1350,7 +1372,7 @@ test "shape Chakma vowel sign with ligature (vowel sign renders first)" {
     buf_idx += try std.unicode.utf8Encode(0x1112c, buf[buf_idx..]); // Vowel Sign U
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1398,6 +1420,7 @@ test "shape Bengali ligatures with out of order vowels" {
 
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // We need a font that supports Bengali for this to work, if we can't find
     // Arial Unicode MS, which is a system font on macOS, we just skip the
@@ -1425,7 +1448,7 @@ test "shape Bengali ligatures with out of order vowels" {
     buf_idx += try std.unicode.utf8Encode(0x09c7, buf[buf_idx..]); // Vowel sign E
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 30, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 30, .rows = 3 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -1472,6 +1495,7 @@ test "shape Bengali ligatures with out of order vowels" {
 test "shape box glyphs" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
@@ -1482,7 +1506,7 @@ test "shape box glyphs" {
     buf_idx += try std.unicode.utf8Encode(0x2501, buf[buf_idx..]); //
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1516,12 +1540,13 @@ test "shape box glyphs" {
 test "shape selection boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1621,12 +1646,13 @@ test "shape selection boundary" {
 test "shape cursor boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     // Make a screen with some data
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1758,12 +1784,14 @@ test "shape cursor boundary" {
 test "shape cursor boundary and colored emoji" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     // Make a screen with some data
     var t = try terminal.Terminal.init(
+        io,
         alloc,
         .{ .cols = 3, .rows = 10 },
     );
@@ -1857,13 +1885,14 @@ test "shape cursor boundary and colored emoji" {
 test "shape cell attribute change" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var testdata = try testShaper(alloc);
     defer testdata.deinit();
 
     // Plain >= should shape into 1 run
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 3 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 3 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1889,7 +1918,7 @@ test "shape cell attribute change" {
 
     // Bold vs regular should split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1917,7 +1946,7 @@ test "shape cell attribute change" {
 
     // Changing fg color should split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1948,7 +1977,7 @@ test "shape cell attribute change" {
 
     // Changing bg color should not split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
@@ -1979,7 +2008,7 @@ test "shape cell attribute change" {
 
     // Same bg color should not split
     {
-        var t = try terminal.Terminal.init(alloc, .{ .cols = 3, .rows = 10 });
+        var t = try terminal.Terminal.init(io, alloc, .{ .cols = 3, .rows = 10 });
         defer t.deinit(alloc);
 
         var s = t.vtStream();
diff --git a/src/font/sprite/Face.zig b/src/font/sprite/Face.zig
index fd029d139..e2e37d2af 100644
--- a/src/font/sprite/Face.zig
+++ b/src/font/sprite/Face.zig
@@ -273,15 +273,16 @@ fn testDiffAtlas(
     // Get the file contents, we compare the PNG data first in
     // order to ensure that no one smuggles arbitrary binary
     // data in to the reference PNGs.
-    const test_file = try std.fs.openFileAbsolute(path, .{ .mode = .read_only });
-    defer test_file.close();
-    const test_bytes = try test_file.readToEndAlloc(
+    const test_file = try std.Io.Dir.openFileAbsolute(std.testing.io, path, .{ .mode = .read_only });
+    defer test_file.close(std.testing.io);
+    var test_file_reader = test_file.reader(std.testing.io, &.{});
+    const test_bytes = try test_file_reader.interface.readAlloc(
         alloc,
-        std.math.maxInt(usize),
+        (try test_file.stat(std.testing.io)).size,
     );
     defer alloc.free(test_bytes);
 
-    const cwd_absolute = try std.fs.cwd().realpathAlloc(alloc, ".");
+    const cwd_absolute = try std.Io.Dir.cwd().realPathFileAlloc(std.testing.io, ".", alloc);
     defer alloc.free(cwd_absolute);
 
     // Get the reference file contents to compare.
@@ -292,7 +293,7 @@ fn testDiffAtlas(
     );
     defer alloc.free(ref_path);
     const ref_file =
-        std.fs.cwd().openFile(ref_path, .{ .mode = .read_only }) catch |err| {
+        std.Io.Dir.cwd().openFile(std.testing.io, ref_path, .{ .mode = .read_only }) catch |err| {
             log.err("Can't open reference file {s}: {}\n", .{
                 ref_path,
                 err,
@@ -306,14 +307,15 @@ fn testDiffAtlas(
                 .{ cwd_absolute, i, i + 0xFF, width, height, thickness },
             );
             defer alloc.free(test_path);
-            try std.fs.copyFileAbsolute(path, test_path, .{});
+            try std.Io.Dir.copyFileAbsolute(path, test_path, std.testing.io, .{});
 
             return true;
         };
-    defer ref_file.close();
-    const ref_bytes = try ref_file.readToEndAlloc(
+    defer ref_file.close(std.testing.io);
+    var ref_file_reader = ref_file.reader(std.testing.io, &.{});
+    const ref_bytes = try ref_file_reader.interface.readAlloc(
         alloc,
-        std.math.maxInt(usize),
+        (try ref_file.stat(std.testing.io)).size,
     );
     defer alloc.free(ref_bytes);
 
@@ -330,7 +332,7 @@ fn testDiffAtlas(
         .{ cwd_absolute, i, i + 0xFF, width, height, thickness },
     );
     defer alloc.free(test_path);
-    try std.fs.copyFileAbsolute(path, test_path, .{});
+    try std.Io.Dir.copyFileAbsolute(path, test_path, std.testing.io, .{});
 
     // Use wuffs to decode the reference PNG to raw pixels.
     // These will be RGBA, so when diffing we can just compare
@@ -394,7 +396,7 @@ fn testDiffAtlas(
         .{ i, i + 0xFF, width, height, thickness },
     );
     defer alloc.free(diff_path);
-    try z2d.png_exporter.writeToPNGFile(diff, diff_path, .{});
+    try z2d.png_exporter.writeToPNGFile(std.testing.io, diff, diff_path, .{});
     log.err(
         "One or more glyphs differ from reference file in range U+{X}...U+{X}! " ++
             "test={s}, reference={s}, diff={s}",
@@ -462,7 +464,7 @@ fn testDrawRanges(
     // Try to make the sprite_face_test folder if it doesn't already exist.
     var dir = testing.tmpDir(.{});
     defer dir.cleanup();
-    const tmp_dir = try dir.dir.realpathAlloc(alloc, ".");
+    const tmp_dir = try dir.dir.realPathFileAlloc(testing.io, ".", alloc);
     defer alloc.free(tmp_dir);
 
     // We set this to true if we have any fails so we can
@@ -481,7 +483,7 @@ fn testDrawRanges(
                     .{ tmp_dir, i, i + 0xFF, width, height, thickness },
                 );
                 defer alloc.free(path);
-                try z2d.png_exporter.writeToPNGFile(atlas, path, .{});
+                try z2d.png_exporter.writeToPNGFile(testing.io, atlas, path, .{});
 
                 if (try testDiffAtlas(
                     alloc,
@@ -526,7 +528,7 @@ fn testDrawRanges(
         .{ tmp_dir, i, i + 0xFF, width, height, thickness },
     );
     defer alloc.free(path);
-    try z2d.png_exporter.writeToPNGFile(atlas, path, .{});
+    try z2d.png_exporter.writeToPNGFile(std.testing.io, atlas, path, .{});
     if (try testDiffAtlas(
         alloc,
         &atlas,
diff --git a/src/font/sprite/canvas.zig b/src/font/sprite/canvas.zig
index 7904f20a5..d400c9cf0 100644
--- a/src/font/sprite/canvas.zig
+++ b/src/font/sprite/canvas.zig
@@ -5,6 +5,7 @@ const assert = @import("../../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const z2d = @import("z2d");
 const font = @import("../main.zig");
+const global = @import("../../global.zig");
 
 pub fn Point(comptime T: type) type {
     return struct {
@@ -255,7 +256,7 @@ pub const Canvas = struct {
 
     /// Acquires a z2d drawing context, caller MUST deinit context.
     pub fn getContext(self: *Canvas) z2d.Context {
-        var ctx = z2d.Context.init(self.alloc, &self.sfc);
+        var ctx = z2d.Context.init(global.io(), self.alloc, &self.sfc);
         // Offset by our padding to keep
         // coordinates relative to the cell.
         ctx.setTransformation(self.transformation());
diff --git a/src/font/sprite/testdata/U+1CC00...U+1CCFF-11x21+2.png b/src/font/sprite/testdata/U+1CC00...U+1CCFF-11x21+2.png
index e04e7726b..00ee592b9 100644
Binary files a/src/font/sprite/testdata/U+1CC00...U+1CCFF-11x21+2.png and b/src/font/sprite/testdata/U+1CC00...U+1CCFF-11x21+2.png differ
diff --git a/src/font/sprite/testdata/U+1CC00...U+1CCFF-12x24+3.png b/src/font/sprite/testdata/U+1CC00...U+1CCFF-12x24+3.png
index ce1b1c422..7b37e5669 100644
Binary files a/src/font/sprite/testdata/U+1CC00...U+1CCFF-12x24+3.png and b/src/font/sprite/testdata/U+1CC00...U+1CCFF-12x24+3.png differ
diff --git a/src/font/sprite/testdata/U+1CC00...U+1CCFF-18x36+4.png b/src/font/sprite/testdata/U+1CC00...U+1CCFF-18x36+4.png
index 1c21f688a..6b19f819a 100644
Binary files a/src/font/sprite/testdata/U+1CC00...U+1CCFF-18x36+4.png and b/src/font/sprite/testdata/U+1CC00...U+1CCFF-18x36+4.png differ
diff --git a/src/font/sprite/testdata/U+1CC00...U+1CCFF-9x17+1.png b/src/font/sprite/testdata/U+1CC00...U+1CCFF-9x17+1.png
index 459822e63..04c9ac6a4 100644
Binary files a/src/font/sprite/testdata/U+1CC00...U+1CCFF-9x17+1.png and b/src/font/sprite/testdata/U+1CC00...U+1CCFF-9x17+1.png differ
diff --git a/src/font/sprite/testdata/U+1CD00...U+1CDFF-11x21+2.png b/src/font/sprite/testdata/U+1CD00...U+1CDFF-11x21+2.png
index 8d7de36ac..898264f39 100644
Binary files a/src/font/sprite/testdata/U+1CD00...U+1CDFF-11x21+2.png and b/src/font/sprite/testdata/U+1CD00...U+1CDFF-11x21+2.png differ
diff --git a/src/font/sprite/testdata/U+1CD00...U+1CDFF-12x24+3.png b/src/font/sprite/testdata/U+1CD00...U+1CDFF-12x24+3.png
index ab6bec96d..59da98bac 100644
Binary files a/src/font/sprite/testdata/U+1CD00...U+1CDFF-12x24+3.png and b/src/font/sprite/testdata/U+1CD00...U+1CDFF-12x24+3.png differ
diff --git a/src/font/sprite/testdata/U+1CD00...U+1CDFF-18x36+4.png b/src/font/sprite/testdata/U+1CD00...U+1CDFF-18x36+4.png
index 43035aefb..e3dff1f31 100644
Binary files a/src/font/sprite/testdata/U+1CD00...U+1CDFF-18x36+4.png and b/src/font/sprite/testdata/U+1CD00...U+1CDFF-18x36+4.png differ
diff --git a/src/font/sprite/testdata/U+1CD00...U+1CDFF-9x17+1.png b/src/font/sprite/testdata/U+1CD00...U+1CDFF-9x17+1.png
index fc111e2d7..6069996bb 100644
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diff --git a/src/global.zig b/src/global.zig
index 29eaf5f36..3c2ddbb72 100644
--- a/src/global.zig
+++ b/src/global.zig
@@ -10,26 +10,374 @@ const oni = @import("oniguruma");
 const crash = @import("crash/main.zig");
 const renderer = @import("renderer.zig");
 const apprt = @import("apprt.zig");
+const assert = @import("quirks.zig").inlineAssert;
+const allocTmpDir = @import("os/file.zig").allocTmpDir;
+const freeTmpDir = @import("os/file.zig").freeTmpDir;
+
+// This file should only be imported for certain platforms.
+comptime {
+    switch (@import("terminal_options").artifact) {
+        .ghostty => {},
+        // This file is not allowed to be included in libghostty-vt
+        .lib => @compileError("global state cannot be used in libghostty-vt"),
+    }
+}
 
 /// We export the xev backend we want to use so that the rest of
 /// Ghostty can import this once and have access to the proper
 /// backend.
 pub const xev = @import("xev").Dynamic;
 
-/// Global process state. This is initialized in main() for exe artifacts
-/// and by ghostty_init() for lib artifacts. This should ONLY be used by
-/// the C API. The Zig API should NOT use any global state and should
-/// rely on allocators being passed in as parameters.
-pub var state: GlobalState = undefined;
+/// Global process state. This is initialized in main() for exe artifacts and
+/// by ghostty_init() for lib artifacts. Most other methods in this file will
+/// retrieve items stored in this state.
+var state: ?GlobalState = null;
+
+pub const InitOpts = union(enum) {
+    main: std.process.Init.Minimal,
+
+    /// Same as `main` but for auxiliary tool binaries (e.g. ghostty-bench
+    /// and ghostty-gen) that have their own CLI action namespace. This
+    /// skips detection of ghostty app CLI actions, since tool actions
+    /// (e.g. `+terminal-stream`) are not valid app actions and would
+    /// otherwise cause init to fail with InvalidAction.
+    tool: std.process.Init.Minimal,
+
+    c: struct {
+        argc: usize,
+        argv: [*][*:0]u8,
+        environ: std.process.Environ,
+    },
+};
+
+/// Initialize the global state.
+pub fn init(opts: InitOpts) !void {
+    // Initialize ourself to nothing so we don't have any extra state.
+    // IMPORTANT: this MUST be initialized before any log output because
+    // the log function uses the global state.
+    state = .{
+        .io_impl = undefined,
+        .gpa = null,
+        .alloc = undefined,
+        .environ = switch (opts) {
+            .main, .tool => |m| m.environ,
+            .c => |c| c.environ,
+        },
+        .args = switch (opts) {
+            .main, .tool => |m| m.args,
+            // TODO: Using the C API from Windows is unsupported at this time.
+            //
+            // When do we plan on supporting Windows, it's recommended to
+            // ensure that the C API can take a UNICODE_STRING (aka []16, a
+            // WTF-16 string) so that it can just be passed into
+            // std.process.Args.Vector directly.
+            .c => |c| .{ .vector = if (builtin.os.tag == .windows)
+                return error.UnsupportedOSForCApi
+            else
+                c.argv[0..c.argc] },
+        },
+        .tmp_dir_path = null,
+        .action = null,
+        .logging = .{},
+        .rlimits = .{},
+        .resources_dir = .{},
+    };
+    const self = &state.?;
+    errdefer deinit();
+
+    self.gpa = gpa: {
+        // Use the libc allocator if it is available because it is WAY
+        // faster than GPA. We only do this in release modes so that we
+        // can get easy memory leak detection in debug modes.
+        if (builtin.link_libc) {
+            if (switch (builtin.mode) {
+                .ReleaseSafe, .ReleaseFast => true,
+
+                // We also use it if we can detect we're running under
+                // Valgrind since Valgrind only instruments the C allocator
+                else => std.valgrind.runningOnValgrind() > 0,
+            }) break :gpa null;
+        }
+
+        break :gpa .init;
+    };
+
+    self.alloc = if (self.gpa) |*value|
+        value.allocator()
+    else if (builtin.link_libc)
+        std.heap.c_allocator
+    else
+        unreachable;
+
+    // Set up our main I/O implementation (fully threaded w/allocator). Note
+    // that we cannot use any implementation supplied from main at this point,
+    // because there are some later initialization steps that depend on us
+    // mutating the environment, and thus it needs to be re-synced farther
+    // down. For that, we need a stable implementation that allows us to do so.
+    self.io_impl = .init(self.alloc, .{
+        .argv0 = .init(self.args),
+        .environ = self.environ,
+    });
+
+    // Discover and save the temporary directory path
+    self.tmp_dir_path = try allocTmpDir(self.alloc, self.environ);
+
+    // We first try to parse any action that we may be executing.
+    // Tool binaries (ghostty-bench, ghostty-gen) have their own action
+    // namespace and detect their own actions, so we skip detection here.
+    self.action = switch (opts) {
+        .main, .c => try cli.action.detectArgs(
+            cli.ghostty.Action,
+            self.alloc,
+            self.args,
+        ),
+        .tool => null,
+    };
+
+    // If we have an action executing, we disable logging by default
+    // since we write to stderr we don't want logs messing up our
+    // output.
+    if (self.action != null) self.logging.stderr = false;
+
+    // I don't love the env var name but I don't have it in my heart
+    // to parse CLI args 3 times (once for actions, once for config,
+    // maybe once for logging) so for now this is an easy way to do
+    // this. Env vars are useful for logging too because they are
+    // easy to set.
+    logging: {
+        const v = self.environ.getAlloc(self.alloc, "GHOSTTY_LOG") catch |err| switch (err) {
+            error.EnvironmentVariableMissing => break :logging,
+            else => return err,
+        };
+        defer self.alloc.free(v);
+        self.logging = cli.args.parsePackedStruct(GlobalState.Logging, v) catch .{};
+    }
+
+    // Setup our signal handlers before logging
+    GlobalState.initSignals();
+
+    // Setup our Xev backend if we're dynamic
+    if (comptime xev.dynamic) xev.detect() catch |err| {
+        std.log.warn("failed to detect xev backend, falling back to " ++
+            "most compatible backend err={}", .{err});
+    };
+
+    // Output some debug information right away
+    std.log.info("ghostty version={s}", .{build_config.version_string});
+    std.log.info("ghostty build optimize={s}", .{build_config.mode_string});
+    std.log.info("runtime={}", .{build_config.app_runtime});
+    std.log.info("font_backend={}", .{build_config.font_backend});
+    if (comptime build_config.font_backend.hasHarfbuzz()) {
+        std.log.info("dependency harfbuzz={s}", .{harfbuzz.versionString()});
+    }
+    if (comptime build_config.font_backend.hasFontconfig()) {
+        std.log.info("dependency fontconfig={d}", .{fontconfig.version()});
+    }
+    std.log.info("renderer={}", .{renderer.Renderer});
+    std.log.info("libxev default backend={t}", .{xev.backend});
+
+    // As early as possible, initialize our resource limits.
+    self.rlimits = .init();
+
+    // Initialize our crash reporting.
+    crash.init(self.alloc) catch |err| {
+        std.log.warn(
+            "sentry init failed, no crash capture available err={}",
+            .{err},
+        );
+    };
+
+    // const sentrylib = @import("sentry");
+    // if (sentrylib.captureEvent(sentrylib.Value.initMessageEvent(
+    //     .info,
+    //     null,
+    //     "hello, world",
+    // ))) |uuid| {
+    //     std.log.warn("uuid={s}", .{uuid.string()});
+    // } else std.log.warn("failed to capture event", .{});
+
+    // We need to make sure the process locale is set properly. Locale
+    // affects a lot of behaviors in a shell.
+    //
+    // We need to re-sync the environment after this completes.
+    try internal_os.ensureLocale();
+    syncEnviron();
+
+    // Initialize glslang for shader compilation
+    try glslang.init();
+
+    // Initialize oniguruma for regex
+    try oni.init(&.{oni.Encoding.utf8});
+
+    // Find our resources directory once for the app so every launch
+    // hereafter can use this cached value.
+    self.resources_dir = try apprt.runtime.resourcesDir(self.alloc);
+    errdefer self.resources_dir.deinit(self.alloc);
+
+    // Setup i18n
+    if (self.resources_dir.app()) |v| internal_os.i18n.init(v) catch |err| {
+        std.log.warn("failed to init i18n, translations will not be available err={}", .{err});
+    };
+}
+
+/// Cleans up the global state. This doesn't _need_ to be called but
+/// doing so in dev modes will check for memory leaks.
+///
+/// Asserts that the state exists.
+pub fn deinit() void {
+    const self = &state.?;
+
+    self.resources_dir.deinit(self.alloc);
+
+    // Flush our crash logs
+    crash.deinit();
+
+    // Release our tmp_dir_path if needed
+    if (self.tmp_dir_path) |td| freeTmpDir(self.alloc, td);
+
+    // Release our I/O instance
+    self.io_impl.deinit();
+
+    if (self.gpa) |*value| {
+        // We want to ensure that we deinit the GPA because this is
+        // the point at which it will output if there were safety violations.
+        _ = value.deinit();
+    }
+}
+
+/// Helper to return either the state's I/O instance, or one from testing.
+///
+/// Asserts that the global state is initialized when not running as as test.
+pub fn io() std.Io {
+    if (builtin.is_test) return std.testing.io;
+
+    return state.?.io();
+}
+
+/// Helper to return either the state's I/O instance, or one from testing.
+///
+/// Asserts that the global state is initialized when not running as as test.
+pub fn alloc() std.mem.Allocator {
+    if (builtin.is_test) return std.testing.allocator;
+
+    return state.?.alloc;
+}
+
+/// Helper to return either the state's environment, or one from testing.
+///
+/// Asserts that the global state is initialized when not running as a test.
+pub fn environ() std.process.Environ {
+    if (builtin.is_test) return std.testing.environ;
+
+    return state.?.environ;
+}
+
+/// Helper to create an environment map off of the state's environment, or one
+/// from testing. The map is created off of the state allocator.
+///
+/// Asserts that the global state is initialized when not running as a test.
+pub fn environMap() !std.process.Environ.Map {
+    if (builtin.is_test) return std.testing.environ.createMap(std.testing.allocator);
+
+    return state.?.environ.createMap(state.?.alloc);
+}
+
+/// Re-synchronizes the global Environ (both the higher-level and I/O versions)
+/// from the process. No-op on Windows, asserts libc and an initialized global
+/// state on everything else.
+///
+/// It is not valid to run this within any code that needs to be run through
+/// tests. For any of these, re-factor the code to take an environment map
+/// instead, where you can modify the environment as needed.
+///
+/// NOTE: Be cognizant of where you are calling this! While the only real
+/// difference between the POSIX environment and higher-level Zig `PosixBlock`
+/// struct is that the latter has a length versus the former's many-item
+/// pointer state, there is no concurrency control on this function (or for
+/// that matter, `environ` or `environMap`. Direct modification of the system
+/// environment is becoming more discouraged in the standard library as well,
+/// and this should be kept in mind when resorting to lower-level `setenv` or
+/// `unsetenv` - as a rule, beyond initialization, favor
+/// `std.process.Environ.Map` whenever possible.
+pub fn syncEnviron() void {
+    switch (builtin.os.tag) {
+        .windows => {},
+        else => {
+            assert(builtin.link_libc);
+            assert(!builtin.is_test);
+            const new_environ: std.process.Environ = .{ .block = .{ .slice = std.c.environ[0..env_len: {
+                var len: usize = 0;
+                while (std.c.environ[len]) |_| : (len += 1) {}
+                break :env_len len;
+            } :null] } };
+            state.?.environ = new_environ;
+            state.?.io_impl.environ = .{ .process_environ = new_environ };
+        },
+    }
+}
+
+/// Helper to return either the state's args, or one from testing.
+///
+/// Asserts that the global state is initialized when not running as a test.
+pub fn args() std.process.Args {
+    if (builtin.is_test) return .{ .vector = &.{} };
+
+    return state.?.args;
+}
+
+/// Returns the temporary directory discovered from the global environment
+/// (saves allocation of the temporary directory where you can get at global
+/// state).
+///
+/// Asserts that the global state is initialized.
+pub fn tmpDirPath() []const u8 {
+    return state.?.tmp_dir_path.?;
+}
+
+/// Returns the global state resources_dir, or an empty one when testing.
+///
+/// Asserts that the global state is initialized when not running as a test.
+pub fn resourcesDir() internal_os.ResourcesDir {
+    if (builtin.is_test) return .{};
+
+    return state.?.resources_dir;
+}
+
+/// Returns the global state rlimits, or an empty one when testing.
+///
+/// Asserts that the global state is initialized when not running as a test.
+pub fn rlimits() ResourceLimits {
+    if (builtin.is_test) return .{};
+
+    return state.?.rlimits;
+}
+
+/// Returns the global state logging configuration.
+///
+/// Asserts that the global state is initialized.
+pub fn logging() GlobalState.Logging {
+    return state.?.logging;
+}
+
+/// Returns the global state action.
+///
+/// Asserts that the global state is initialized.
+pub fn action() ?cli.ghostty.Action {
+    return state.?.action;
+}
 
 /// This represents the global process state. There should only
 /// be one of these at any given moment. This is extracted into a dedicated
 /// struct because it is reused by main and the static C lib.
 pub const GlobalState = struct {
-    const GPA = std.heap.GeneralPurposeAllocator(.{});
+    const GPA = std.heap.DebugAllocator(.{});
 
+    io_impl: std.Io.Threaded,
     gpa: ?GPA,
     alloc: std.mem.Allocator,
+    environ: std.process.Environ,
+    args: std.process.Args,
+    tmp_dir_path: ?[]const u8,
     action: ?cli.ghostty.Action,
     logging: Logging,
     rlimits: ResourceLimits = .{},
@@ -48,151 +396,9 @@ pub const GlobalState = struct {
         macos: bool = builtin.os.tag.isDarwin(),
     };
 
-    /// Initialize the global state.
-    pub fn init(self: *GlobalState) !void {
-        // const start = try std.time.Instant.now();
-        // const start_micro = std.time.microTimestamp();
-        // defer {
-        //     const end = std.time.Instant.now() catch unreachable;
-        //     // "[updateFrame critical time] <START us>\t<TIME_TAKEN us>"
-        //     std.log.err("[global init time] start={}us duration={}ns", .{ start_micro, end.since(start) / std.time.ns_per_us });
-        // }
-
-        // Initialize ourself to nothing so we don't have any extra state.
-        // IMPORTANT: this MUST be initialized before any log output because
-        // the log function uses the global state.
-        self.* = .{
-            .gpa = null,
-            .alloc = undefined,
-            .action = null,
-            .logging = .{},
-            .rlimits = .{},
-            .resources_dir = .{},
-        };
-        errdefer self.deinit();
-
-        self.gpa = gpa: {
-            // Use the libc allocator if it is available because it is WAY
-            // faster than GPA. We only do this in release modes so that we
-            // can get easy memory leak detection in debug modes.
-            if (builtin.link_libc) {
-                if (switch (builtin.mode) {
-                    .ReleaseSafe, .ReleaseFast => true,
-
-                    // We also use it if we can detect we're running under
-                    // Valgrind since Valgrind only instruments the C allocator
-                    else => std.valgrind.runningOnValgrind() > 0,
-                }) break :gpa null;
-            }
-
-            break :gpa GPA{};
-        };
-
-        self.alloc = if (self.gpa) |*value|
-            value.allocator()
-        else if (builtin.link_libc)
-            std.heap.c_allocator
-        else
-            unreachable;
-
-        // We first try to parse any action that we may be executing.
-        self.action = try cli.action.detectArgs(
-            cli.ghostty.Action,
-            self.alloc,
-        );
-
-        // If we have an action executing, we disable logging by default
-        // since we write to stderr we don't want logs messing up our
-        // output.
-        if (self.action != null) self.logging.stderr = false;
-
-        // I don't love the env var name but I don't have it in my heart
-        // to parse CLI args 3 times (once for actions, once for config,
-        // maybe once for logging) so for now this is an easy way to do
-        // this. Env vars are useful for logging too because they are
-        // easy to set.
-        if ((try internal_os.getenv(self.alloc, "GHOSTTY_LOG"))) |v| {
-            defer v.deinit(self.alloc);
-            self.logging = cli.args.parsePackedStruct(Logging, v.value) catch .{};
-        }
-
-        // Setup our signal handlers before logging
-        initSignals();
-
-        // Setup our Xev backend if we're dynamic
-        if (comptime xev.dynamic) xev.detect() catch |err| {
-            std.log.warn("failed to detect xev backend, falling back to " ++
-                "most compatible backend err={}", .{err});
-        };
-
-        // Output some debug information right away
-        std.log.info("ghostty version={s}", .{build_config.version_string});
-        std.log.info("ghostty build optimize={s}", .{build_config.mode_string});
-        std.log.info("runtime={}", .{build_config.app_runtime});
-        std.log.info("font_backend={}", .{build_config.font_backend});
-        if (comptime build_config.font_backend.hasHarfbuzz()) {
-            std.log.info("dependency harfbuzz={s}", .{harfbuzz.versionString()});
-        }
-        if (comptime build_config.font_backend.hasFontconfig()) {
-            std.log.info("dependency fontconfig={d}", .{fontconfig.version()});
-        }
-        std.log.info("renderer={}", .{renderer.Renderer});
-        std.log.info("libxev default backend={t}", .{xev.backend});
-
-        // As early as possible, initialize our resource limits.
-        self.rlimits = .init();
-
-        // Initialize our crash reporting.
-        crash.init(self.alloc) catch |err| {
-            std.log.warn(
-                "sentry init failed, no crash capture available err={}",
-                .{err},
-            );
-        };
-
-        // const sentrylib = @import("sentry");
-        // if (sentrylib.captureEvent(sentrylib.Value.initMessageEvent(
-        //     .info,
-        //     null,
-        //     "hello, world",
-        // ))) |uuid| {
-        //     std.log.warn("uuid={s}", .{uuid.string()});
-        // } else std.log.warn("failed to capture event", .{});
-
-        // We need to make sure the process locale is set properly. Locale
-        // affects a lot of behaviors in a shell.
-        try internal_os.ensureLocale(self.alloc);
-
-        // Initialize glslang for shader compilation
-        try glslang.init();
-
-        // Initialize oniguruma for regex
-        try oni.init(&.{oni.Encoding.utf8});
-
-        // Find our resources directory once for the app so every launch
-        // hereafter can use this cached value.
-        self.resources_dir = try apprt.runtime.resourcesDir(self.alloc);
-        errdefer self.resources_dir.deinit(self.alloc);
-
-        // Setup i18n
-        if (self.resources_dir.app()) |v| internal_os.i18n.init(v) catch |err| {
-            std.log.warn("failed to init i18n, translations will not be available err={}", .{err});
-        };
-    }
-
-    /// Cleans up the global state. This doesn't _need_ to be called but
-    /// doing so in dev modes will check for memory leaks.
-    pub fn deinit(self: *GlobalState) void {
-        self.resources_dir.deinit(self.alloc);
-
-        // Flush our crash logs
-        crash.deinit();
-
-        if (self.gpa) |*value| {
-            // We want to ensure that we deinit the GPA because this is
-            // the point at which it will output if there were safety violations.
-            _ = value.deinit();
-        }
+    /// Asserts that `self.io_impl` has been initialized.
+    pub fn io(self: *GlobalState) std.Io {
+        return self.io_impl.io();
     }
 
     fn initSignals() void {
diff --git a/src/helpgen.zig b/src/helpgen.zig
index 49b5f4439..e12cbda01 100644
--- a/src/helpgen.zig
+++ b/src/helpgen.zig
@@ -7,12 +7,9 @@ const Config = @import("config/Config.zig");
 const Action = @import("cli/ghostty.zig").Action;
 const KeybindAction = @import("input/Binding.zig").Action;
 
-pub fn main() !void {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-    const alloc = gpa.allocator();
-
+pub fn main(init: std.process.Init) !void {
     var buf: [4096]u8 = undefined;
-    var stdout = std.fs.File.stdout().writerStreaming(&buf);
+    var stdout = std.Io.File.stdout().writerStreaming(init.io, &buf);
     const writer = &stdout.interface;
     try writer.writeAll(
         \\// THIS FILE IS AUTO GENERATED
@@ -20,6 +17,7 @@ pub fn main() !void {
         \\
     );
 
+    const alloc = init.arena.allocator();
     try genConfig(alloc, writer);
     try genActions(alloc, writer);
     try genKeybindActions(alloc, writer);
diff --git a/src/input/Binding.zig b/src/input/Binding.zig
index d60f2933b..8c706027a 100644
--- a/src/input/Binding.zig
+++ b/src/input/Binding.zig
@@ -1439,30 +1439,35 @@ pub const Action = union(enum) {
         const all_fields = @typeInfo(Action).@"union".fields;
 
         // Find all fields that are app-scoped
-        var i: usize = 0;
-        var union_fields: [all_fields.len]std.builtin.Type.UnionField = undefined;
-        var enum_fields: [all_fields.len]std.builtin.Type.EnumField = undefined;
+        var i: comptime_int = 0;
+        var names: [all_fields.len][]const u8 = undefined;
+        var types: [all_fields.len]type = undefined;
+        var attrs: [all_fields.len]std.builtin.Type.UnionField.Attributes = undefined;
+        var raw_values: [all_fields.len]comptime_int = undefined;
+
         for (all_fields) |field| {
             const action = @unionInit(Action, field.name, undefined);
             if (action.scope() == s) {
-                union_fields[i] = field;
-                enum_fields[i] = .{ .name = field.name, .value = i };
+                names[i] = field.name;
+                types[i] = field.type;
+                attrs[i] = .{ .@"align" = field.alignment };
+                raw_values[i] = i;
                 i += 1;
             }
         }
 
+        const TagInt = std.math.IntFittingRange(0, i);
+        var values: [i]TagInt = undefined;
+        for (raw_values[0..i], &values) |raw, *v| v.* = raw;
+
         // Build our union
-        return @Type(.{ .@"union" = .{
-            .layout = .auto,
-            .tag_type = @Type(.{ .@"enum" = .{
-                .tag_type = std.math.IntFittingRange(0, i),
-                .fields = enum_fields[0..i],
-                .decls = &.{},
-                .is_exhaustive = true,
-            } }),
-            .fields = union_fields[0..i],
-            .decls = &.{},
-        } });
+        return @Union(
+            .auto,
+            @Enum(TagInt, .exhaustive, names[0..i], &values),
+            names[0..i],
+            types[0..i],
+            attrs[0..i],
+        );
     }
 
     /// Returns the scoped version of this action. If the action is not
diff --git a/src/input/key.zig b/src/input/key.zig
index 9c04f01e0..1bf64919a 100644
--- a/src/input/key.zig
+++ b/src/input/key.zig
@@ -352,8 +352,7 @@ pub const Key = enum(c_int) {
         )) |key| return key;
 
         // We need to convert FooBar to foo_bar
-        var fbs = std.io.fixedBufferStream(&result);
-        const w = fbs.writer();
+        var w: std.Io.Writer = .fixed(&result);
         for (code, 0..) |ch, i| switch (ch) {
             'a'...'z' => w.writeByte(ch) catch return null,
 
@@ -367,7 +366,7 @@ pub const Key = enum(c_int) {
             else => return null,
         };
 
-        return std.meta.stringToEnum(Key, fbs.getWritten());
+        return std.meta.stringToEnum(Key, w.buffered());
     }
 
     /// Converts a Ghostty key enum value to a W3C key code.
@@ -379,8 +378,7 @@ pub const Key = enum(c_int) {
                 const name = @tagName(tag);
 
                 var buf: [128]u8 = undefined;
-                var fbs = std.io.fixedBufferStream(&buf);
-                const w = fbs.writer();
+                var w: std.Io.Writer = .fixed(&buf);
                 var i: usize = 0;
                 while (i < name.len) {
                     if (i == 0) {
@@ -396,7 +394,7 @@ pub const Key = enum(c_int) {
                 }
 
                 const written = buf;
-                const result = written[0..fbs.getWritten().len];
+                const result = written[0..w.end];
                 break :w3c result;
             },
         };
diff --git a/src/input/key_mods.zig b/src/input/key_mods.zig
index 35e1c1038..1a9814037 100644
--- a/src/input/key_mods.zig
+++ b/src/input/key_mods.zig
@@ -368,12 +368,11 @@ pub const RemapSet = struct {
             const to = entry.value_ptr.*;
 
             var buf: [64]u8 = undefined;
-            var fbs = std.io.fixedBufferStream(&buf);
-            const writer = fbs.writer();
-            formatMod(writer, from) catch return error.OutOfMemory;
+            var writer: std.Io.Writer = .fixed(&buf);
+            formatMod(&writer, from) catch return error.OutOfMemory;
             writer.writeByte('=') catch return error.OutOfMemory;
-            formatMod(writer, to) catch return error.OutOfMemory;
-            try formatter.formatEntry([]const u8, fbs.getWritten());
+            formatMod(&writer, to) catch return error.OutOfMemory;
+            try formatter.formatEntry([]const u8, writer.buffered());
         }
     }
 
diff --git a/src/inspector/Inspector.zig b/src/inspector/Inspector.zig
index 22d763f73..d1dc04f17 100644
--- a/src/inspector/Inspector.zig
+++ b/src/inspector/Inspector.zig
@@ -92,8 +92,6 @@ pub fn recordKeyEvent(
             events.deleteOldest(1);
             try events.append(ev);
         },
-
-        else => return err,
     };
 }
 
diff --git a/src/inspector/widgets/key.zig b/src/inspector/widgets/key.zig
index 7d7188a6b..2a3f531ea 100644
--- a/src/inspector/widgets/key.zig
+++ b/src/inspector/widgets/key.zig
@@ -232,8 +232,7 @@ fn modsTooltip(
     mods: *const input.Mods,
     buf: []u8,
 ) ![:0]const u8 {
-    var stream = std.io.fixedBufferStream(buf);
-    const writer = stream.writer();
+    var writer: std.Io.Writer = .fixed(buf);
     var first = true;
     if (mods.shift) {
         try writer.writeAll("Shift");
@@ -254,7 +253,7 @@ fn modsTooltip(
         try writer.writeAll("Super");
     }
     try writer.writeByte(0);
-    const written = stream.getWritten();
+    const written = writer.buffered();
     return written[0 .. written.len - 1 :0];
 }
 
@@ -403,8 +402,7 @@ pub const Stream = struct {
                 cimgui.c.ImGui_TextDisabled("-");
             } else {
                 var utf8_buf: [128]u8 = undefined;
-                var utf8_stream = std.io.fixedBufferStream(&utf8_buf);
-                const utf8_writer = utf8_stream.writer();
+                var utf8_writer: std.Io.Writer = .fixed(&utf8_buf);
                 if (std.unicode.Utf8View.init(ev.event.utf8)) |view| {
                     var utf8_it = view.iterator();
                     while (utf8_it.nextCodepoint()) |cp| {
@@ -423,8 +421,7 @@ pub const Stream = struct {
                 cimgui.c.ImGui_TextDisabled("-");
             } else {
                 var pty_buf: [256]u8 = undefined;
-                var pty_stream = std.io.fixedBufferStream(&pty_buf);
-                const pty_writer = pty_stream.writer();
+                var pty_writer: std.Io.Writer = .fixed(&pty_buf);
                 for (ev.pty) |byte| {
                     if (byte == 0x1B) {
                         pty_writer.writeAll("ESC ") catch break;
@@ -444,8 +441,7 @@ pub const Stream = struct {
                 cimgui.c.ImGui_TextDisabled("-");
             } else {
                 var binding_buf: [256]u8 = undefined;
-                var binding_stream = std.io.fixedBufferStream(&binding_buf);
-                const binding_writer = binding_stream.writer();
+                var binding_writer: std.Io.Writer = .fixed(&binding_buf);
                 for (ev.binding, 0..) |action, i| {
                     if (i > 0) binding_writer.writeAll(", ") catch break;
                     binding_writer.writeAll(@tagName(action)) catch break;
diff --git a/src/inspector/widgets/surface.zig b/src/inspector/widgets/surface.zig
index a630bad87..28bd1def0 100644
--- a/src/inspector/widgets/surface.zig
+++ b/src/inspector/widgets/surface.zig
@@ -9,6 +9,7 @@ const input = @import("../../input.zig");
 const renderer = @import("../../renderer.zig");
 const terminal = @import("../../terminal/main.zig");
 const Surface = @import("../../Surface.zig");
+const global = @import("../../global.zig");
 
 /// This is discovered via the hardcoded string in the ImGui demo window.
 const window_imgui_demo = "Dear ImGui Demo";
@@ -56,8 +57,8 @@ pub const Inspector = struct {
 
         // Draw everything that requires the terminal state mutex.
         {
-            surface.renderer_state.mutex.lock();
-            defer surface.renderer_state.mutex.unlock();
+            surface.renderer_state.mutex.lockUncancelable(global.io());
+            defer surface.renderer_state.mutex.unlock(global.io());
             const t = surface.renderer_state.terminal;
 
             // Terminal info window
@@ -442,7 +443,7 @@ fn mouseTable(
                 if (state != .press) continue;
                 const button: input.MouseButton = @enumFromInt(i);
                 cimgui.c.ImGui_SameLine();
-                cimgui.c.ImGui_Text("%s", (switch (button) {
+                cimgui.c.ImGui_Text("%s", @as([*]const u8, @ptrCast(switch (button) {
                     .unknown => "?",
                     .left => "L",
                     .middle => "M",
@@ -455,7 +456,7 @@ fn mouseTable(
                     .nine => "{9}",
                     .ten => "{10}",
                     .eleven => "{11}",
-                }).ptr);
+                })));
             }
         }
     }
diff --git a/src/inspector/widgets/termio.zig b/src/inspector/widgets/termio.zig
index b721d9422..04574f4ce 100644
--- a/src/inspector/widgets/termio.zig
+++ b/src/inspector/widgets/termio.zig
@@ -793,8 +793,6 @@ const VTHandler = struct {
                 vt_events.deleteOldest(1);
                 try vt_events.append(ev);
             },
-
-            else => return err,
         };
 
         // Do NOT skip it, because we want to record more information
diff --git a/src/lib/compat/README.md b/src/lib/compat/README.md
new file mode 100644
index 000000000..22f58c100
--- /dev/null
+++ b/src/lib/compat/README.md
@@ -0,0 +1,37 @@
+# Zig Compatibility Libraries
+
+The following directory contains code that either used to exist in the Zig
+standard library, or currently exists in Zig master that has been deemed
+useful to have ahead of a full release.
+
+Code located here should likely be eventually phased out, or moved to a more
+logical location if it's decided it would be useful to keep.
+
+## Licenses
+
+Zig code taken from the standard library is used under the terms of the MIT
+license. The license body follows.
+
+```
+The MIT License (Expat)
+
+Copyright (c) Zig contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+```
diff --git a/src/lib/compat/fd.zig b/src/lib/compat/fd.zig
new file mode 100644
index 000000000..3bef74144
--- /dev/null
+++ b/src/lib/compat/fd.zig
@@ -0,0 +1,83 @@
+//! Code taken from 0.15.2 and `std.fs.file`. See README.md for license and
+//! details.
+const std = @import("std");
+
+pub const PipeError = error{
+    SystemFdQuotaExceeded,
+    ProcessFdQuotaExceeded,
+} || std.posix.UnexpectedError;
+
+pub fn close(fd: std.posix.fd_t) void {
+    switch (std.posix.errno(std.posix.system.close(fd))) {
+        .BADF => unreachable, // Always a race condition
+        else => {}, // Includes EINTR, see std.posix source in 0.15.2
+    }
+}
+
+pub fn pipe() PipeError![2]std.posix.fd_t {
+    var fds: [2]std.posix.fd_t = undefined;
+    switch (std.posix.errno(std.posix.system.pipe(&fds))) {
+        .SUCCESS => return fds,
+        .INVAL => unreachable, // Invalid parameters to pipe()
+        .FAULT => unreachable, // Invalid fds pointer
+        .NFILE => return error.SystemFdQuotaExceeded,
+        .MFILE => return error.ProcessFdQuotaExceeded,
+        else => |err| return std.posix.unexpectedErrno(err),
+    }
+}
+
+pub fn pipe2(flags: std.posix.O) PipeError![2]std.posix.fd_t {
+    if (@TypeOf(std.posix.system.pipe2) != void) {
+        var fds: [2]std.posix.fd_t = undefined;
+        switch (std.posix.errno(std.posix.system.pipe2(&fds, flags))) {
+            .SUCCESS => return fds,
+            .INVAL => unreachable, // Invalid flags
+            .FAULT => unreachable, // Invalid fds pointer
+            .NFILE => return error.SystemFdQuotaExceeded,
+            .MFILE => return error.ProcessFdQuotaExceeded,
+            else => |err| return std.posix.unexpectedErrno(err),
+        }
+    }
+
+    const fds: [2]std.posix.fd_t = try pipe();
+    errdefer {
+        close(fds[0]);
+        close(fds[1]);
+    }
+
+    // https://github.com/ziglang/zig/issues/18882
+    if (@as(u32, @bitCast(flags)) == 0)
+        return fds;
+
+    // CLOEXEC is special, it's a file descriptor flag and must be set using
+    // F.SETFD.
+    if (flags.CLOEXEC) {
+        for (fds) |fd| {
+            switch (std.posix.errno(std.posix.system.fcntl(fd, std.posix.F.SETFD, @as(u32, std.posix.FD_CLOEXEC)))) {
+                .SUCCESS => {},
+                .INVAL => unreachable, // Invalid flags
+                .BADF => unreachable, // Always a race condition
+                else => |err| return std.posix.unexpectedErrno(err),
+            }
+        }
+    }
+
+    const new_flags: u32 = f: {
+        var new_flags = flags;
+        new_flags.CLOEXEC = false;
+        break :f @bitCast(new_flags);
+    };
+    // Set every other flag affecting the file status using F.SETFL.
+    if (new_flags != 0) {
+        for (fds) |fd| {
+            switch (std.posix.errno(std.posix.system.fcntl(fd, std.posix.F.SETFL, new_flags))) {
+                .SUCCESS => {},
+                .INVAL => unreachable, // Invalid flags
+                .BADF => unreachable, // Always a race condition
+                else => |err| return std.posix.unexpectedErrno(err),
+            }
+        }
+    }
+
+    return fds;
+}
diff --git a/src/lib/compat/file.zig b/src/lib/compat/file.zig
new file mode 100644
index 000000000..efb31a525
--- /dev/null
+++ b/src/lib/compat/file.zig
@@ -0,0 +1,56 @@
+//! Code taken from 0.15.2 and `std.fs.file`. See README.md for license and
+//! details.
+const builtin = @import("builtin");
+const std = @import("std");
+const global = @import("../../global.zig");
+
+pub const ReadToEndAllocError = error{FileTooBig} ||
+    std.Io.File.ReadStreamingError ||
+    std.mem.Allocator.Error;
+
+/// Read the file from its current position through end-of-stream, returning
+/// `error.FileTooBig` if the result exceeds `max_bytes`.
+///
+/// Caller owns the memory.
+pub fn readToEndAlloc(file: std.Io.File, alloc: std.mem.Allocator, max_bytes: usize) ReadToEndAllocError![]u8 {
+    var read_buf: [4096]u8 = undefined;
+    var result: std.ArrayList(u8) = .empty;
+    defer result.deinit(alloc);
+
+    while (true) {
+        const n = file.readStreaming(global.io(), &.{&read_buf}) catch |err| switch (err) {
+            error.EndOfStream => break,
+            else => |e| return e,
+        };
+        if (n == 0) continue;
+        if (n > max_bytes - result.items.len) return error.FileTooBig;
+        try result.appendSlice(alloc, read_buf[0..n]);
+    }
+
+    return result.toOwnedSlice(alloc);
+}
+
+test "readToEndAlloc reads through EOF and permits exact limit" {
+    const testing = std.testing;
+    const contents = "hello, world";
+
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
+    try tmp_dir.dir.writeFile(testing.io, .{
+        .sub_path = "data",
+        .data = contents,
+    });
+
+    const file = try tmp_dir.dir.openFile(testing.io, "data", .{});
+    defer file.close(testing.io);
+    const result = try readToEndAlloc(file, testing.allocator, contents.len);
+    defer testing.allocator.free(result);
+    try testing.expectEqualStrings(contents, result);
+
+    const too_big_file = try tmp_dir.dir.openFile(testing.io, "data", .{});
+    defer too_big_file.close(testing.io);
+    try testing.expectError(
+        error.FileTooBig,
+        readToEndAlloc(too_big_file, testing.allocator, contents.len - 1),
+    );
+}
diff --git a/src/lib/compat/reader.zig b/src/lib/compat/reader.zig
new file mode 100644
index 000000000..288134408
--- /dev/null
+++ b/src/lib/compat/reader.zig
@@ -0,0 +1,64 @@
+//! Code taken from older reader implementations, still may be useful to keep
+//! around in general. See README.md for license and details.
+const std = @import("std");
+
+/// Pulled from old stdlib as this function has been removed.
+pub fn readSkipUntilDelimiterOrEof(reader: *std.Io.Reader, delimiter: u8) std.Io.Reader.Error!void {
+    while (true) {
+        const byte = readByte(reader) catch |err| switch (err) {
+            error.EndOfStream => return,
+            else => |e| return e,
+        };
+        if (byte == delimiter) return;
+    }
+}
+
+/// Pulled from old stdlib as this function has been removed.
+pub fn readStructEndian(
+    reader: *std.Io.Reader,
+    comptime T: type,
+    endian: std.builtin.Endian,
+) std.Io.Reader.Error!T {
+    var result: [1]T = undefined;
+    try reader.readSliceEndian(T, &result, endian);
+    return result[0];
+}
+
+/// Pulled from old stdlib as this function has been removed.
+pub fn readerInt(reader: *std.Io.Reader, comptime T: type, endian: std.builtin.Endian) std.Io.Reader.Error!T {
+    const bytes = try readBytesNoEof(reader, @divExact(@typeInfo(T).int.bits, 8));
+    return std.mem.readInt(T, &bytes, endian);
+}
+
+/// Pulled from old stdlib as this function has been removed.
+pub fn readByteSigned(reader: *std.Io.Reader) std.Io.Reader.Error!i8 {
+    return @as(i8, @bitCast(try readByte(reader)));
+}
+
+/// Pulled from old stdlib as this function has been removed.
+pub fn readByte(reader: *std.Io.Reader) std.Io.Reader.Error!u8 {
+    var result: [1]u8 = undefined;
+    try reader.readSliceAll(&result);
+    return result[0];
+}
+
+/// Pulled from old stdlib as this function has been removed.
+pub fn readSkipBytes(reader: *std.Io.Reader, num_bytes: u64) std.Io.Reader.Error!void {
+    const buf_size = 512;
+
+    var buf: [buf_size]u8 = undefined;
+    var remaining = num_bytes;
+
+    while (remaining > 0) {
+        const amt = @min(remaining, buf_size);
+        try reader.readSliceAll(buf[0..amt]);
+        remaining -= amt;
+    }
+}
+
+/// Pulled from old stdlib as this function has been removed.
+fn readBytesNoEof(reader: *std.Io.Reader, comptime num_bytes: usize) std.Io.Reader.Error![num_bytes]u8 {
+    var bytes: [num_bytes]u8 = undefined;
+    try reader.readSliceAll(&bytes);
+    return bytes;
+}
diff --git a/src/lib/compat/testing.zig b/src/lib/compat/testing.zig
new file mode 100644
index 000000000..e826eb404
--- /dev/null
+++ b/src/lib/compat/testing.zig
@@ -0,0 +1,19 @@
+//! Code taken from 0.15.2 `std.testing`. See README.md for license and
+//! details.
+const builtin = @import("builtin");
+const std = @import("std");
+
+/// Given a type, recursively references all the declarations inside, so that the semantic analyzer sees them.
+/// For deep types, you may use `@setEvalBranchQuota`.
+pub fn refAllDeclsRecursive(comptime T: type) void {
+    if (!builtin.is_test) return;
+    inline for (comptime std.meta.declarations(T)) |decl| {
+        if (@TypeOf(@field(T, decl.name)) == type) {
+            switch (@typeInfo(@field(T, decl.name))) {
+                .@"struct", .@"enum", .@"union", .@"opaque" => refAllDeclsRecursive(@field(T, decl.name)),
+                else => {},
+            }
+        }
+        _ = &@field(T, decl.name);
+    }
+}
diff --git a/src/lib/compat/thread.zig b/src/lib/compat/thread.zig
new file mode 100644
index 000000000..890c02f0c
--- /dev/null
+++ b/src/lib/compat/thread.zig
@@ -0,0 +1,75 @@
+//! Code taken from 0.17.0 `std.Io.Condition`. See README.md for license and
+//! details.
+//!
+//! FIXME: Should be able to remove after 0.17.0, see:
+//!   https://codeberg.org/ziglang/zig/pulls/31278
+const builtin = @import("builtin");
+const std = @import("std");
+const assert = @import("../../quirks.zig").inlineAssert;
+
+pub const WaitTimeoutError = std.Io.Cancelable || std.Io.Timeout.Error;
+
+/// Blocks until the condition is signaled, canceled, or the provided
+/// timeout expires.
+///
+/// See also:
+/// * `wait`
+/// * `waitUncancelable`
+pub fn waitTimeout(
+    cond: *std.Io.Condition,
+    io: std.Io,
+    mutex: *std.Io.Mutex,
+    timeout: std.Io.Timeout,
+) WaitTimeoutError!void {
+    const deadline = timeout.toDeadline(io);
+
+    var epoch = cond.epoch.load(.acquire); // `.acquire` to ensure ordered before state load
+
+    {
+        const prev_state = cond.state.fetchAdd(.{ .waiters = 1, .signals = 0 }, .monotonic);
+        assert(prev_state.waiters < std.math.maxInt(u16)); // overflow caused by too many waiters
+    }
+
+    mutex.unlock(io);
+    defer mutex.lockUncancelable(io);
+
+    while (true) {
+        const result = io.futexWaitTimeout(u32, &cond.epoch.raw, epoch, deadline);
+
+        epoch = cond.epoch.load(.acquire); // `.acquire` to ensure ordered before `state` load
+
+        // Even on error, try to consume a pending signal first. Otherwise a race might
+        // cause a signal to get stuck in the state with no corresponding waiter.
+        {
+            var prev_state = cond.state.load(.monotonic);
+            while (prev_state.signals > 0) {
+                prev_state = cond.state.cmpxchgWeak(prev_state, .{
+                    .waiters = prev_state.waiters - 1,
+                    .signals = prev_state.signals - 1,
+                }, .acquire, .monotonic) orelse {
+                    // We successfully consumed a signal.
+                    return;
+                };
+            }
+        }
+
+        // There are no more signals available; this was a spurious wakeup or an error. If it
+        // was an error, we will remove ourselves as a waiter and return that error. If a
+        // timeout was specified and the deadline has passed, we remove ourselves as a waiter
+        // and return `error.Timeout`. Otherwise, we'll loop back to the futex wait.
+        result catch |err| {
+            const prev_state = cond.state.fetchSub(.{ .waiters = 1, .signals = 0 }, .monotonic);
+            assert(prev_state.waiters > 0); // underflow caused by illegal state
+            return err;
+        };
+        switch (deadline) {
+            .none => {},
+            .deadline => |d| if (d.untilNow(io).raw.nanoseconds >= 0) {
+                const prev_state = cond.state.fetchSub(.{ .waiters = 1, .signals = 0 }, .monotonic);
+                assert(prev_state.waiters > 0); // underflow caused by illegal state
+                return error.Timeout;
+            },
+            .duration => unreachable,
+        }
+    }
+}
diff --git a/src/lib/enum.zig b/src/lib/enum.zig
index 76e05fa93..bfc86bbf7 100644
--- a/src/lib/enum.zig
+++ b/src/lib/enum.zig
@@ -21,42 +21,38 @@ pub fn Enum(
     target: Target,
     keys: []const ?[:0]const u8,
 ) type {
-    var fields: [keys.len]std.builtin.Type.EnumField = undefined;
-    var fields_i: usize = 0;
-    var holes: usize = 0;
-    for (keys) |key_| {
-        const key: [:0]const u8 = key_ orelse {
-            switch (target) {
-                // For Zig we don't track holes because the enum value
-                // isn't guaranteed to be stable and we want to use the
-                // smallest possible backing type.
-                .zig => {},
-
-                // For C we must track holes to preserve ABI compatibility
-                // with subsequent values.
-                .c => holes += 1,
+    var names_raw: [keys.len][]const u8 = undefined;
+    var values_raw: [keys.len]comptime_int = undefined;
+    const names_actual, const values_actual = kv: {
+        // Remove any holes in the input (null values). As mentioned in the
+        // function docs, in the event of the C ABI, we need to preserve the
+        // original value, so we account for that.
+        var to: comptime_int = 0;
+        for (0..keys.len) |from| {
+            if (keys[from]) |key| {
+                names_raw[to] = key;
+                values_raw[to] = if (target == .c) from else to;
+                to += 1;
             }
-            continue;
-        };
+        }
 
-        fields[fields_i] = .{
-            .name = key,
-            .value = fields_i + holes,
-        };
-        fields_i += 1;
-    }
+        break :kv .{ names_raw[0..to], values_raw[0..to] };
+    };
 
-    // Assigned to var so that the type name is nicer in stack traces.
-    const Result = @Type(.{ .@"enum" = .{
-        .tag_type = switch (target) {
-            .c => c_int,
-            .zig => std.math.IntFittingRange(0, fields_i - 1),
-        },
-        .fields = fields[0..fields_i],
-        .decls = &.{},
-        .is_exhaustive = true,
-    } });
-    return Result;
+    const TagInt = switch (target) {
+        .c => c_int,
+        .zig => std.math.IntFittingRange(0, names_actual.len - 1),
+    };
+
+    return @Enum(TagInt, .exhaustive, names_actual, &(values: {
+        // We have to transform our comptime_int values into the actual int
+        // we're creating the enum as.
+        var result_int_values: [values_actual.len]TagInt = undefined;
+        for (0..values_actual.len) |idx| {
+            result_int_values[idx] = values_actual[idx];
+        }
+        break :values result_int_values;
+    }));
 }
 
 test "zig" {
diff --git a/src/lib/struct.zig b/src/lib/struct.zig
index bbf07ece3..262e037fa 100644
--- a/src/lib/struct.zig
+++ b/src/lib/struct.zig
@@ -20,23 +20,21 @@ pub fn Struct(
         .zig => Zig,
         .c => c: {
             const info = @typeInfo(Zig).@"struct";
-            var fields: [info.fields.len]std.builtin.Type.StructField = undefined;
-            for (info.fields, 0..) |field, i| {
-                fields[i] = .{
-                    .name = field.name,
-                    .type = field.type,
+            var names: [info.fields.len][]const u8 = undefined;
+            var types: [info.fields.len]type = undefined;
+            var attrs: [info.fields.len]std.builtin.Type.StructField.Attributes = undefined;
+
+            for (info.fields, &names, &types, &attrs) |field, *name, *ty, *attr| {
+                name.* = field.name;
+                ty.* = field.type;
+                attr.* = .{
+                    .@"align" = field.alignment,
+                    .@"comptime" = field.is_comptime,
                     .default_value_ptr = field.default_value_ptr,
-                    .is_comptime = field.is_comptime,
-                    .alignment = if (field.alignment > 0) field.alignment else @alignOf(field.type),
                 };
             }
 
-            break :c @Type(.{ .@"struct" = .{
-                .layout = .@"extern",
-                .fields = &fields,
-                .decls = &.{},
-                .is_tuple = info.is_tuple,
-            } });
+            break :c @Struct(.@"extern", null, &names, &types, &attrs);
         },
     };
 }
diff --git a/src/lib/union.zig b/src/lib/union.zig
index 924d0e864..63a34a8cb 100644
--- a/src/lib/union.zig
+++ b/src/lib/union.zig
@@ -60,7 +60,10 @@ pub fn TaggedUnion(
             }
 
             const tag_fields = @typeInfo(Tag).@"enum".fields;
-            var union_fields: [tag_fields.len + 1]std.builtin.Type.UnionField = undefined;
+            var names: [tag_fields.len + 1][]const u8 = undefined;
+            var types: [tag_fields.len + 1]type = undefined;
+            var attrs: [tag_fields.len + 1]std.builtin.Type.UnionField.Attributes = undefined;
+
             for (tag_fields, 0..) |field, i| {
                 const action = @unionInit(Union, field.name, undefined);
                 const Type = t: {
@@ -74,25 +77,16 @@ pub fn TaggedUnion(
                     break :t Type;
                 };
 
-                union_fields[i] = .{
-                    .name = field.name,
-                    .type = Type,
-                    .alignment = @alignOf(Type),
-                };
+                names[i] = field.name;
+                types[i] = Type;
+                attrs[i] = .{ .@"align" = @alignOf(Type) };
             }
 
-            union_fields[tag_fields.len] = .{
-                .name = "_padding",
-                .type = Padding,
-                .alignment = @alignOf(Padding),
-            };
+            names[tag_fields.len] = "_padding";
+            types[tag_fields.len] = Padding;
+            attrs[tag_fields.len] = .{ .@"align" = @alignOf(Padding) };
 
-            break :cvalue @Type(.{ .@"union" = .{
-                .layout = .@"extern",
-                .tag_type = null,
-                .fields = &union_fields,
-                .decls = &.{},
-            } });
+            break :cvalue @Union(.@"extern", null, &names, &types, &attrs);
         };
 
         /// Convert to C union.
diff --git a/src/lib_vt.zig b/src/lib_vt.zig
index e01cdbb89..b4a2722bf 100644
--- a/src/lib_vt.zig
+++ b/src/lib_vt.zig
@@ -145,6 +145,12 @@ comptime {
     // If we're building the C library (vs. the Zig module) then
     // we want to reference the C API so that it gets exported.
     if (@import("root") == lib) {
+        // Force-reference our memset override so its export is
+        // emitted. This must stay inside the root guard so that
+        // downstream Zig module consumers don't get the override
+        // injected into their binaries. See quirks_memset.zig.
+        _ = @import("quirks_memset.zig");
+
         const c = terminal.c_api;
         @export(&c.key_event_new, .{ .name = "ghostty_key_event_new" });
         @export(&c.key_event_free, .{ .name = "ghostty_key_event_free" });
@@ -339,30 +345,53 @@ comptime {
     }
 }
 
-pub const std_options: std.Options = options: {
-    if (builtin.target.cpu.arch.isWasm()) break :options .{
+pub const std_options: std.Options = opts: {
+    var options: std.Options = .{};
+
+    if (builtin.target.cpu.arch.isWasm()) {
         // Wasm builds we specifically want to optimize for space with small
         // releases so we bump up to warn. Everything else acts pretty normal.
-        .log_level = switch (builtin.mode) {
+        options.log_level = switch (builtin.mode) {
             .Debug => .debug,
             .ReleaseSmall => .warn,
             else => .info,
-        },
+        };
 
         // Wasm doesn't have access to stdio so we have a custom log function.
-        .logFn = @import("os/wasm/log.zig").log,
-    };
+        options.logFn = @import("os/wasm/log.zig").log;
+    } else if (terminal.options.c_abi) {
+        // For C ABI builds, use a custom log function that dispatches to an
+        // embedder-provided callback (or silently discards when none is set).
+        options.logFn = @import("terminal/c/sys.zig").logFn;
+    }
 
-    // For C ABI builds, use a custom log function that dispatches to an
-    // embedder-provided callback (or silently discards when none is set).
-    if (terminal.options.c_abi) break :options .{
-        .logFn = @import("terminal/c/sys.zig").logFn,
-    };
+    if (builtin.target.os.tag.isDarwin() and builtin.target.os.tag != .macos) {
+        // If are building for a non-MacOS Darwin target (e.g., iOS), we need to
+        // disable stack tracing for the time being. This is due to the fact that
+        // Zig switched to using _dyld_get_image_header_containing_address and some
+        // other (deprecated) calls to speed up stack unwinding; these calls are
+        // available on MacOS, but not on other platforms.
+        //
+        // A fix has already been submitted to exempt non-MacOS (but still Darwin)
+        // targets, so this can likely be removed in Zig 0.17.0, or a 0.16.x patch
+        // version if it releases beforehand.
+        //
+        // More details:
+        //   https://codeberg.org/ziglang/zig/commit/89f86e46d278a35a613bbc662cdd3f65ffc76ed7
+        //
+        options.allow_stack_tracing = false;
+    }
 
-    break :options .{};
+    break :opts options;
 };
 
 test {
+    // Zig 0.16.0 has made test logging more strict. Now, *anything* that gets
+    // printed to stderr results in a "failed command" message, even if the
+    // tests ultimately passed. To reduce confusion here (and honestly, test
+    // log spam in general), we bump the default testing log level to error.
+    @import("std").testing.log_level = std.log.Level.err;
+
     _ = terminal;
     _ = @import("lib/main.zig");
     @import("std").testing.refAllDecls(input);
diff --git a/src/main.zig b/src/main.zig
index b08e63dd2..fe41640ab 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -21,6 +21,18 @@ pub const std_options: std.Options = if (@hasDecl(entrypoint, "std_options"))
 else
     .{};
 
-test {
-    _ = entrypoint;
+comptime {
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
+}
+
+test {
+    // Zig 0.16.0 has made test logging more strict. Now, *anything* that gets
+    // printed to stderr results in a "failed command" message, even if the
+    // tests ultimately passed. To reduce confusion here (and honestly, test
+    // log spam in general), we bump the default testing log level to error.
+    std.testing.log_level = std.log.Level.err;
+    _ = entrypoint;
+    _ = @import("quirks_memset.zig");
 }
diff --git a/src/main_bench.zig b/src/main_bench.zig
index 9804f51ef..c48724903 100644
--- a/src/main_bench.zig
+++ b/src/main_bench.zig
@@ -1,3 +1,9 @@
 const benchmark = @import("benchmark/main.zig");
 
+comptime {
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
+}
+
 pub const main = benchmark.cli.main;
diff --git a/src/main_build_data.zig b/src/main_build_data.zig
index 4e55f449d..b441e3779 100644
--- a/src/main_build_data.zig
+++ b/src/main_build_data.zig
@@ -27,14 +27,14 @@ pub const Action = enum {
     terminfo,
 };
 
-pub fn main() !void {
+pub fn main(init: std.process.Init) !void {
     const alloc = std.heap.c_allocator;
-    const action_ = try cli.action.detectArgs(Action, alloc);
+    const action_ = try cli.action.detectArgs(Action, alloc, init.minimal.args);
     const action = action_ orelse return error.NoAction;
 
     // Our output always goes to stdout.
     var buffer: [1024]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writerStreaming(&buffer);
+    var stdout_writer = std.Io.File.stdout().writerStreaming(init.io, &buffer);
     const writer = &stdout_writer.interface;
     switch (action) {
         .bash => try writer.writeAll(@import("extra/bash.zig").completions),
diff --git a/src/main_c.zig b/src/main_c.zig
index f61565f26..3e331e022 100644
--- a/src/main_c.zig
+++ b/src/main_c.zig
@@ -13,9 +13,10 @@ const posix = std.posix;
 const builtin = @import("builtin");
 const build_config = @import("build_config.zig");
 const main = @import("main_ghostty.zig");
-const state = &@import("global.zig").state;
+const global = @import("global.zig");
 const apprt = @import("apprt.zig");
 const internal_os = @import("os/main.zig");
+const windows = @import("os/windows.zig");
 
 // Some comptime assertions that our C API depends on.
 comptime {
@@ -43,6 +44,10 @@ comptime {
     // Our benchmark API. We probably want to gate this on a build
     // config in the future but for now we always just export it.
     _ = @import("benchmark/main.zig").CApi;
+
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
 }
 
 /// ghostty_info_s
@@ -94,9 +99,9 @@ pub const String = extern struct {
     pub fn deinit(self: *const String) void {
         const ptr = self.ptr orelse return;
         if (self.sentinel) {
-            state.alloc.free(ptr[0..self.len :0]);
+            global.alloc().free(ptr[0..self.len :0]);
         } else {
-            state.alloc.free(ptr[0..self.len]);
+            global.alloc().free(ptr[0..self.len]);
         }
     }
 };
@@ -105,8 +110,23 @@ pub const String = extern struct {
 pub export fn ghostty_init(argc: usize, argv: [*][*:0]u8) c_int {
     assert(builtin.link_libc);
 
-    std.os.argv = argv[0..argc];
-    state.init() catch |err| {
+    global.init(.{
+        .c = .{
+            .argc = argc,
+            .argv = argv,
+            .environ = if (std.process.Environ.Block == std.process.Environ.PosixBlock)
+                // Asserting libc means that we can fast-path all POSIX blocks
+                .{ .block = .{ .slice = std.c.environ[0..env_len: {
+                    var len: usize = 0;
+                    while (std.c.environ[len]) |_| : (len += 1) {}
+                    break :env_len len;
+                } :null] } }
+            else
+                // Anything that is not using PosixBlock is a global block for
+                // purposes of initialization.
+                .{ .block = .{ .use_global = true } },
+        },
+    }) catch |err| {
         std.log.err("failed to initialize ghostty error={}", .{err});
         return 1;
     };
@@ -117,14 +137,14 @@ pub export fn ghostty_init(argc: usize, argv: [*][*:0]u8) c_int {
 /// Runs an action if it is specified. If there is no action this returns
 /// false. If there is an action then this doesn't return.
 pub export fn ghostty_cli_try_action() void {
-    const action = state.action orelse return;
+    const action = global.action() orelse return;
     std.log.info("executing CLI action={}", .{action});
-    posix.exit(action.run(state.alloc) catch |err| {
+    posix.system.exit(action.run(global.alloc()) catch |err| {
         std.log.err("CLI action failed error={}", .{err});
-        posix.exit(1);
+        posix.system.exit(1);
     });
 
-    posix.exit(0);
+    posix.system.exit(0);
 }
 
 /// Return metadata about Ghostty, such as version, build mode, etc.
@@ -172,12 +192,12 @@ pub export fn ghostty_string_free(str: String) void {
 // Closest: Codeberg ziglang/zig #30936 (reimplement crt0 code).
 // Remove this DllMain when Zig handles MSVC DLL CRT init natively.
 pub const DllMain = if (builtin.os.tag == .windows) struct {
-    const BOOL = std.os.windows.BOOL;
-    const HINSTANCE = std.os.windows.HINSTANCE;
-    const DWORD = std.os.windows.DWORD;
-    const LPVOID = std.os.windows.LPVOID;
-    const TRUE = std.os.windows.TRUE;
-    const FALSE = std.os.windows.FALSE;
+    const BOOL = windows.BOOL;
+    const HINSTANCE = windows.HINSTANCE;
+    const DWORD = windows.DWORD;
+    const LPVOID = windows.LPVOID;
+    const TRUE = windows.TRUE;
+    const FALSE = windows.FALSE;
 
     const DLL_PROCESS_ATTACH: DWORD = 1;
     const DLL_PROCESS_DETACH: DWORD = 0;
@@ -217,7 +237,6 @@ test "ghostty_string_s empty string" {
 
 test "ghostty_string_s c string" {
     const testing = std.testing;
-    state.alloc = testing.allocator;
 
     const slice: [:0]const u8 = "hello";
     const allocated_slice = try testing.allocator.dupeZ(u8, slice);
@@ -233,7 +252,6 @@ test "ghostty_string_s c string" {
 
 test "ghostty_string_s zig string" {
     const testing = std.testing;
-    state.alloc = testing.allocator;
 
     const slice: []const u8 = "hello";
     const allocated_slice = try testing.allocator.dupe(u8, slice);
diff --git a/src/main_gen.zig b/src/main_gen.zig
index 3342bc2e9..d4df3b9ec 100644
--- a/src/main_gen.zig
+++ b/src/main_gen.zig
@@ -1,3 +1,9 @@
 const synthetic = @import("synthetic/main.zig");
 
+comptime {
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
+}
+
 pub const main = synthetic.cli.main;
diff --git a/src/main_ghostty.zig b/src/main_ghostty.zig
index 531a06461..cd2ef0c17 100644
--- a/src/main_ghostty.zig
+++ b/src/main_ghostty.zig
@@ -13,7 +13,7 @@ const apprt = @import("apprt.zig");
 
 const App = @import("App.zig");
 const Ghostty = @import("main_c.zig").Ghostty;
-const state = &@import("global.zig").state;
+const global = @import("global.zig");
 
 /// The return type for main() depends on the build artifact. The lib build
 /// also calls "main" in order to run the CLI actions, but it calls it as
@@ -23,16 +23,19 @@ const MainReturn = switch (build_config.artifact) {
     else => void,
 };
 
-pub fn main() !MainReturn {
+pub fn main(minimal: std.process.Init.Minimal) !MainReturn {
     // We first start by initializing our global state. This will setup
     // process-level state we need to run the terminal. The reason we use
     // a global is because the C API needs to be able to access this state;
     // no other Zig code should EVER access the global state.
-    state.init() catch |err| {
+    global.init(.{ .main = minimal }) catch |err| {
         var buffer: [1024]u8 = undefined;
-        var stderr_writer = std.fs.File.stderr().writer(&buffer);
+        var stderr_writer = std.Io.File.stderr().writer(
+            std.Io.Threaded.global_single_threaded.io(),
+            &buffer,
+        );
         const stderr = &stderr_writer.interface;
-        defer posix.exit(1);
+        defer std.process.exit(1);
         const ErrSet = @TypeOf(err) || error{Unknown};
         switch (@as(ErrSet, @errorCast(err))) {
             error.MultipleActions => try stderr.print(
@@ -52,8 +55,8 @@ pub fn main() !MainReturn {
         }
         try stderr.flush();
     };
-    defer state.deinit();
-    const alloc = state.alloc;
+    defer global.deinit();
+    const alloc = global.alloc();
 
     if (comptime builtin.mode == .Debug) {
         std.log.warn("This is a debug build. Performance will be very poor.", .{});
@@ -62,9 +65,9 @@ pub fn main() !MainReturn {
     }
 
     // Execute our action if we have one
-    if (state.action) |action| {
+    if (global.action()) |action| {
         std.log.info("executing CLI action={}", .{action});
-        posix.exit(action.run(alloc) catch |err| err: {
+        std.process.exit(action.run(alloc) catch |err| err: {
             std.log.err("CLI action failed error={}", .{err});
             break :err 1;
         });
@@ -90,7 +93,7 @@ pub fn main() !MainReturn {
             .{},
         );
 
-        posix.exit(0);
+        std.process.exit(0);
     }
 
     // Create our app state
@@ -125,7 +128,7 @@ fn logFn(
     // macOS logging is thread safe so no need for locks/mutexes
     macos: {
         if (comptime !builtin.target.os.tag.isDarwin()) break :macos;
-        if (!state.logging.macos) break :macos;
+        if (!global.logging().macos) break :macos;
 
         const prefix = if (scope == .default) "" else @tagName(scope) ++ ": ";
 
@@ -149,17 +152,17 @@ fn logFn(
         if (comptime builtin.mode != .Debug and level == .debug) break :stderr;
 
         // skip if we are not logging to stderr
-        if (!state.logging.stderr) break :stderr;
+        if (!global.logging().stderr) break :stderr;
 
         // Lock so we are thread-safe
         var buf: [64]u8 = undefined;
-        const stderr = std.debug.lockStderrWriter(&buf);
-        defer std.debug.unlockStderrWriter();
+        const stderr = std.debug.lockStderr(&buf);
+        defer std.debug.unlockStderr();
 
         const level_txt = comptime level.asText();
         const prefix = if (scope == .default) ": " else "(" ++ @tagName(scope) ++ "): ";
-        nosuspend stderr.print(level_txt ++ prefix ++ format ++ "\n", args) catch break :stderr;
-        nosuspend stderr.flush() catch break :stderr;
+        nosuspend stderr.file_writer.interface.print(level_txt ++ prefix ++ format ++ "\n", args) catch break :stderr;
+        nosuspend stderr.file_writer.interface.flush() catch break :stderr;
     }
 }
 
@@ -176,6 +179,24 @@ pub const std_options: std.Options = .{
     },
 
     .logFn = logFn,
+
+    // If are building for a non-MacOS Darwin target (e.g., iOS), we need to
+    // disable stack tracing for the time being. This is due to the fact that
+    // Zig switched to using _dyld_get_image_header_containing_address and some
+    // other (deprecated) calls to speed up stack unwinding; these calls are
+    // available on MacOS, but not on other platforms.
+    //
+    // A fix has already been submitted to exempt non-MacOS (but still Darwin)
+    // targets, so this can likely be removed in Zig 0.17.0, or a 0.16.x patch
+    // version if it releases beforehand.
+    //
+    // More details:
+    //   https://codeberg.org/ziglang/zig/commit/89f86e46d278a35a613bbc662cdd3f65ffc76ed7
+    //
+    .allow_stack_tracing = if (builtin.target.os.tag.isDarwin() and builtin.target.os.tag != .macos)
+        false
+    else
+        builtin.strip_debug_info,
 };
 
 test {
diff --git a/src/os/TempDir.zig b/src/os/TempDir.zig
index c3d344d9d..f093ac3a7 100644
--- a/src/os/TempDir.zig
+++ b/src/os/TempDir.zig
@@ -3,8 +3,9 @@
 const TempDir = @This();
 
 const std = @import("std");
-const Dir = std.fs.Dir;
+const Dir = std.Io.Dir;
 const file = @import("file.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.tempdir);
 
@@ -27,10 +28,10 @@ pub fn init() !TempDir {
     var tmp_path_buf: [file.random_basename_len:0]u8 = undefined;
 
     const dir = dir: {
-        const cwd = std.fs.cwd();
-        const tmp_dir = try file.allocTmpDir(std.heap.page_allocator);
+        const cwd = std.Io.Dir.cwd();
+        const tmp_dir = try file.allocTmpDir(std.heap.page_allocator, global.environ());
         defer file.freeTmpDir(std.heap.page_allocator, tmp_dir);
-        break :dir try cwd.openDir(tmp_dir, .{});
+        break :dir try cwd.openDir(global.io(), tmp_dir, .{});
     };
 
     // We now loop forever until we can find a directory that we can create.
@@ -38,13 +39,13 @@ pub fn init() !TempDir {
         const tmp_path = try file.randomBasename(&tmp_path_buf);
         tmp_path_buf[tmp_path.len] = 0;
 
-        dir.makeDir(tmp_path) catch |err| switch (err) {
+        dir.createDir(global.io(), tmp_path, .default_dir) catch |err| switch (err) {
             error.PathAlreadyExists => continue,
             else => |e| return e,
         };
 
         return TempDir{
-            .dir = try dir.openDir(tmp_path, .{}),
+            .dir = try dir.openDir(global.io(), tmp_path, .{}),
             .parent = dir,
             .name_buf = tmp_path_buf,
         };
@@ -60,8 +61,8 @@ pub fn name(self: *TempDir) []const u8 {
 /// Finish with the temporary directory. This deletes all contents in the
 /// directory.
 pub fn deinit(self: *TempDir) void {
-    self.dir.close();
-    self.parent.deleteTree(self.name()) catch |err|
+    self.dir.close(global.io());
+    self.parent.deleteTree(global.io(), self.name()) catch |err|
         log.err("error deleting temp dir err={}", .{err});
 }
 
@@ -75,10 +76,10 @@ test {
     try testing.expect(nameval.len > 0);
 
     // Can open a new handle to it proves it exists.
-    var dir = try td.parent.openDir(nameval, .{});
-    dir.close();
+    var dir = try td.parent.openDir(testing.io, nameval, .{});
+    dir.close(testing.io);
 
     // Should be deleted after we deinit
     td.deinit();
-    try testing.expectError(error.FileNotFound, td.parent.openDir(nameval, .{}));
+    try testing.expectError(error.FileNotFound, td.parent.openDir(testing.io, nameval, .{}));
 }
diff --git a/src/os/args.zig b/src/os/args.zig
deleted file mode 100644
index 9ef5bba40..000000000
--- a/src/os/args.zig
+++ /dev/null
@@ -1,130 +0,0 @@
-const std = @import("std");
-const builtin = @import("builtin");
-const Allocator = std.mem.Allocator;
-const objc = @import("objc");
-const macos = @import("macos");
-
-/// Returns an iterator over the command line arguments. This may or may
-/// not allocate depending on the platform.
-///
-/// For Zig-aware readers: this is the same as std.process.argsWithAllocator
-/// but handles macOS using NSProcessInfo instead of libc argc/argv.
-pub fn iterator(allocator: Allocator) ArgIterator.InitError!ArgIterator {
-    //if (true) return try std.process.argsWithAllocator(allocator);
-    return .initWithAllocator(allocator);
-}
-
-/// Duck-typed to std.process.ArgIterator
-pub const ArgIterator = switch (builtin.os.tag) {
-    .macos => IteratorMacOS,
-    else => std.process.ArgIterator,
-};
-
-/// This is an ArgIterator (duck-typed for std.process.ArgIterator) for
-/// NSApplicationMain-based applications on macOS. It uses NSProcessInfo to
-/// get the command line arguments since libc argc/argv pointers are not
-/// valid.
-///
-/// I believe this should work for all macOS applications even if
-/// NSApplicationMain is not used, but I haven't tested that so I'm not
-/// sure. If/when libghostty is ever used outside of NSApplicationMain
-/// then we can revisit this.
-const IteratorMacOS = struct {
-    alloc: Allocator,
-    index: usize,
-    count: usize,
-    buf: [:0]u8,
-    args: objc.Object,
-
-    pub const InitError = Allocator.Error;
-
-    pub fn initWithAllocator(alloc: Allocator) InitError!IteratorMacOS {
-        const NSProcessInfo = objc.getClass("NSProcessInfo").?;
-        const info = NSProcessInfo.msgSend(objc.Object, objc.sel("processInfo"), .{});
-        const args = info.getProperty(objc.Object, "arguments");
-        errdefer args.release();
-
-        // Determine our maximum length so we can allocate the buffer to
-        // fit all values.
-        var max: usize = 0;
-        const count: usize = @intCast(args.getProperty(c_ulong, "count"));
-        for (0..count) |i| {
-            const nsstr = args.msgSend(
-                objc.Object,
-                objc.sel("objectAtIndex:"),
-                .{@as(c_ulong, @intCast(i))},
-            );
-
-            const maxlen: usize = @intCast(nsstr.msgSend(
-                c_ulong,
-                objc.sel("maximumLengthOfBytesUsingEncoding:"),
-                .{@as(c_ulong, 4)},
-            ));
-
-            max = @max(max, maxlen);
-        }
-
-        // Allocate our buffer. We add 1 for the null terminator.
-        const buf = try alloc.allocSentinel(u8, max, 0);
-        errdefer alloc.free(buf);
-
-        return .{
-            .alloc = alloc,
-            .index = 0,
-            .count = count,
-            .buf = buf,
-            .args = args,
-        };
-    }
-
-    pub fn deinit(self: *IteratorMacOS) void {
-        self.alloc.free(self.buf);
-
-        // Note: we don't release self.args because it is a pointer copy
-        // not a retained object.
-    }
-
-    pub fn next(self: *IteratorMacOS) ?[:0]const u8 {
-        if (self.index == self.count) return null;
-
-        // NSString. No release because not a copy.
-        const nsstr = self.args.msgSend(
-            objc.Object,
-            objc.sel("objectAtIndex:"),
-            .{@as(c_ulong, @intCast(self.index))},
-        );
-        self.index += 1;
-
-        // Convert to string using getCString. Our buffer should always
-        // be big enough because we precomputed the maximum length.
-        if (!nsstr.msgSend(
-            bool,
-            objc.sel("getCString:maxLength:encoding:"),
-            .{
-                @as([*]u8, @ptrCast(self.buf.ptr)),
-                @as(c_ulong, @intCast(self.buf.len)),
-                @as(c_ulong, 4), // NSUTF8StringEncoding
-            },
-        )) {
-            // This should never happen... if it does, we just return empty.
-            return "";
-        }
-
-        return std.mem.sliceTo(self.buf, 0);
-    }
-
-    pub fn skip(self: *IteratorMacOS) bool {
-        if (self.index == self.count) return false;
-        self.index += 1;
-        return true;
-    }
-};
-
-test "args" {
-    const testing = std.testing;
-    const alloc = testing.allocator;
-
-    var iter = try iterator(alloc);
-    defer iter.deinit();
-    try testing.expect(iter.next().?.len > 0);
-}
diff --git a/src/os/cf_release_thread.zig b/src/os/cf_release_thread.zig
index 445dc4864..e93120b3f 100644
--- a/src/os/cf_release_thread.zig
+++ b/src/os/cf_release_thread.zig
@@ -9,7 +9,8 @@ const builtin = @import("builtin");
 const macos = @import("macos");
 
 const internal_os = @import("../os/main.zig");
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 const BlockingQueue = @import("../datastruct/main.zig").BlockingQueue;
 
 const Allocator = std.mem.Allocator;
@@ -142,11 +143,11 @@ fn threadMain_(self: *Thread) !void {
 fn drainMailbox(self: *Thread) !void {
     // If we're draining, we just drain the mailbox and return.
     if (self.flags.drain) {
-        while (self.mailbox.pop()) |_| {}
+        while (self.mailbox.pop(global.io())) |_| {}
         return;
     }
 
-    while (self.mailbox.pop()) |message| {
+    while (self.mailbox.pop(global.io())) |message| {
         // log.debug("mailbox message={}", .{message});
         switch (message) {
             .release => |msg| {
diff --git a/src/os/cgroup.zig b/src/os/cgroup.zig
index 9e68a50fd..f5eacc6c2 100644
--- a/src/os/cgroup.zig
+++ b/src/os/cgroup.zig
@@ -1,4 +1,5 @@
 const std = @import("std");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"linux-cgroup");
 
@@ -11,16 +12,16 @@ pub fn current(buf: []u8, pid: u32) ?[]const u8 {
     // 0::/user.slice/user-1000.slice/session-1.scope
     // The cgroup path is the third field.
     const path = std.fmt.bufPrint(&path_buf, "/proc/{}/cgroup", .{pid}) catch return null;
-    const file = std.fs.openFileAbsolute(path, .{}) catch return null;
-    defer file.close();
+    const file = std.Io.Dir.openFileAbsolute(global.io(), path, .{}) catch return null;
+    defer file.close(global.io());
 
     var read_buf: [64]u8 = undefined;
-    var file_reader = file.reader(&read_buf);
+    var file_reader = file.reader(global.io(), &read_buf);
     const reader = &file_reader.interface;
     const len = reader.readSliceShort(buf) catch return null;
     const contents = buf[0..len];
 
     // Find the last ':'
     const idx = std.mem.lastIndexOfScalar(u8, contents, ':') orelse return null;
-    return std.mem.trimRight(u8, contents[idx + 1 ..], " \r\n");
+    return std.mem.trimEnd(u8, contents[idx + 1 ..], " \r\n");
 }
diff --git a/src/os/desktop.zig b/src/os/desktop.zig
index 93bfb74bc..16fb7a2cc 100644
--- a/src/os/desktop.zig
+++ b/src/os/desktop.zig
@@ -1,7 +1,7 @@
 const std = @import("std");
 const builtin = @import("builtin");
 const build_config = @import("../build_config.zig");
-const posix = std.posix;
+const global = @import("../global.zig");
 
 const c = @cImport({
     @cInclude("unistd.h");
@@ -26,7 +26,7 @@ pub fn launchedFromDesktop() bool {
             // was launched from the desktop.
             if (build_config.artifact == .lib) lib: {
                 const env = "GHOSTTY_MAC_LAUNCH_SOURCE";
-                const source = posix.getenv(env) orelse break :lib;
+                const source = global.environ().getPosix(env) orelse break :lib;
 
                 // Source can be "app", "cli", or "zig_run". We assume
                 // its the desktop only if its "app". We may want to do
@@ -44,7 +44,7 @@ pub fn launchedFromDesktop() bool {
         // another terminal was launched from a desktop file and then launches
         // Ghostty and Ghostty inherits the env.
         .linux, .freebsd => ul: {
-            const gio_pid_str = posix.getenv("GIO_LAUNCHED_DESKTOP_FILE_PID") orelse
+            const gio_pid_str = global.environ().getPosix("GIO_LAUNCHED_DESKTOP_FILE_PID") orelse
                 break :ul false;
 
             const pid = c.getpid();
@@ -80,7 +80,7 @@ pub const DesktopEnvironment = enum {
 /// Detect what desktop environment we are running under. This is mainly used
 /// on Linux and BSD to enable or disable certain features but there may be more uses in
 /// the future.
-pub fn desktopEnvironment() DesktopEnvironment {
+pub fn desktopEnvironment(environ_map: *const std.process.Environ.Map) DesktopEnvironment {
     return switch (comptime builtin.os.tag) {
         .macos => .macos,
         .windows => .windows,
@@ -89,7 +89,7 @@ pub fn desktopEnvironment() DesktopEnvironment {
 
             // Use $XDG_SESSION_DESKTOP to determine what DE we are using on Linux
             // https://www.freedesktop.org/software/systemd/man/latest/pam_systemd.html#desktop=
-            if (posix.getenv("XDG_SESSION_DESKTOP")) |sd| {
+            if (environ_map.get("XDG_SESSION_DESKTOP")) |sd| {
                 if (std.ascii.eqlIgnoreCase("gnome", sd)) break :de .gnome;
                 if (std.ascii.eqlIgnoreCase("gnome-xorg", sd)) break :de .gnome;
             }
@@ -99,7 +99,7 @@ pub fn desktopEnvironment() DesktopEnvironment {
             // colon-separated list of up to three desktop names, although we
             // only look at the first.
             // https://specifications.freedesktop.org/desktop-entry-spec/latest/recognized-keys.html
-            if (posix.getenv("XDG_CURRENT_DESKTOP")) |cd| {
+            if (environ_map.get("XDG_CURRENT_DESKTOP")) |cd| {
                 var cd_it = std.mem.splitScalar(u8, cd, ':');
                 const cd_first = cd_it.first();
                 if (std.ascii.eqlIgnoreCase(cd_first, "gnome")) break :de .gnome;
@@ -115,45 +115,31 @@ test "desktop environment" {
     const testing = std.testing;
 
     switch (builtin.os.tag) {
-        .macos => try testing.expectEqual(.macos, desktopEnvironment()),
-        .windows => try testing.expectEqual(.windows, desktopEnvironment()),
+        inline .macos, .windows => |tag| {
+            var environ_map = try testing.environ.createMap(testing.allocator);
+            defer environ_map.deinit();
+            try testing.expectEqual(@tagName(tag), @tagName(desktopEnvironment(&environ_map)));
+        },
         .linux, .freebsd => {
-            const getenv = std.posix.getenv;
-            const setenv = @import("env.zig").setenv;
-            const unsetenv = @import("env.zig").unsetenv;
+            var environ_map = try testing.environ.createMap(testing.allocator);
+            defer environ_map.deinit();
 
-            const xdg_current_desktop = getenv("XDG_CURRENT_DESKTOP");
-            defer if (xdg_current_desktop) |v| {
-                _ = setenv("XDG_CURRENT_DESKTOP", v);
-            } else {
-                _ = unsetenv("XDG_CURRENT_DESKTOP");
-            };
-            _ = unsetenv("XDG_CURRENT_DESKTOP");
+            try environ_map.put("XDG_SESSION_DESKTOP", "gnome");
+            try testing.expectEqual(.gnome, desktopEnvironment(&environ_map));
+            try environ_map.put("XDG_SESSION_DESKTOP", "gnome-xorg");
+            try testing.expectEqual(.gnome, desktopEnvironment(&environ_map));
+            try environ_map.put("XDG_SESSION_DESKTOP", "foobar");
+            try testing.expectEqual(.other, desktopEnvironment(&environ_map));
 
-            const xdg_session_desktop = getenv("XDG_SESSION_DESKTOP");
-            defer if (xdg_session_desktop) |v| {
-                _ = setenv("XDG_SESSION_DESKTOP", v);
-            } else {
-                _ = unsetenv("XDG_SESSION_DESKTOP");
-            };
-            _ = unsetenv("XDG_SESSION_DESKTOP");
+            _ = environ_map.orderedRemove("XDG_SESSION_DESKTOP");
+            try testing.expectEqual(.other, desktopEnvironment(&environ_map));
 
-            _ = setenv("XDG_SESSION_DESKTOP", "gnome");
-            try testing.expectEqual(.gnome, desktopEnvironment());
-            _ = setenv("XDG_SESSION_DESKTOP", "gnome-xorg");
-            try testing.expectEqual(.gnome, desktopEnvironment());
-            _ = setenv("XDG_SESSION_DESKTOP", "foobar");
-            try testing.expectEqual(.other, desktopEnvironment());
-
-            _ = unsetenv("XDG_SESSION_DESKTOP");
-            try testing.expectEqual(.other, desktopEnvironment());
-
-            _ = setenv("XDG_CURRENT_DESKTOP", "GNOME");
-            try testing.expectEqual(.gnome, desktopEnvironment());
-            _ = setenv("XDG_CURRENT_DESKTOP", "FOOBAR");
-            try testing.expectEqual(.other, desktopEnvironment());
-            _ = unsetenv("XDG_CURRENT_DESKTOP");
-            try testing.expectEqual(.other, desktopEnvironment());
+            try environ_map.put("XDG_CURRENT_DESKTOP", "GNOME");
+            try testing.expectEqual(.gnome, desktopEnvironment(&environ_map));
+            try environ_map.put("XDG_CURRENT_DESKTOP", "FOOBAR");
+            try testing.expectEqual(.other, desktopEnvironment(&environ_map));
+            _ = environ_map.orderedRemove("XDG_CURRENT_DESKTOP");
+            try testing.expectEqual(.other, desktopEnvironment(&environ_map));
         },
         else => try testing.expectEqual(.other, DesktopEnvironment()),
     }
diff --git a/src/os/env.zig b/src/os/env.zig
deleted file mode 100644
index 8f01a14d0..000000000
--- a/src/os/env.zig
+++ /dev/null
@@ -1,178 +0,0 @@
-const std = @import("std");
-const builtin = @import("builtin");
-const Allocator = std.mem.Allocator;
-const posix = std.posix;
-const isFlatpak = @import("flatpak.zig").isFlatpak;
-
-pub const Error = Allocator.Error;
-
-/// Get the environment map.
-pub fn getEnvMap(alloc: Allocator) !std.process.EnvMap {
-    return if (isFlatpak())
-        std.process.EnvMap.init(alloc)
-    else
-        try std.process.getEnvMap(alloc);
-}
-
-/// Append a value to an environment variable such as PATH.
-/// The returned value is always allocated so it must be freed.
-pub fn appendEnv(
-    alloc: Allocator,
-    current: []const u8,
-    value: []const u8,
-) Error![]u8 {
-    // If there is no prior value, we return it as-is
-    if (current.len == 0) return try alloc.dupe(u8, value);
-
-    // Otherwise we must prefix.
-    return try appendEnvAlways(alloc, current, value);
-}
-
-/// Always append value to environment, even when it is empty.
-/// This is useful because some env vars (like MANPATH) want there
-/// to be an empty prefix to preserve existing values.
-///
-/// The returned value is always allocated so it must be freed.
-pub fn appendEnvAlways(
-    alloc: Allocator,
-    current: []const u8,
-    value: []const u8,
-) Error![]u8 {
-    return try std.fmt.allocPrint(alloc, "{s}{c}{s}", .{
-        current,
-        std.fs.path.delimiter,
-        value,
-    });
-}
-
-/// Prepend a value to an environment variable such as PATH.
-/// The returned value is always allocated so it must be freed.
-pub fn prependEnv(
-    alloc: Allocator,
-    current: []const u8,
-    value: []const u8,
-) Error![]u8 {
-    // If there is no prior value, we return it as-is
-    if (current.len == 0) return try alloc.dupe(u8, value);
-
-    return try std.fmt.allocPrint(alloc, "{s}{c}{s}", .{
-        value,
-        std.fs.path.delimiter,
-        current,
-    });
-}
-
-/// The result of getenv, with a shared deinit to properly handle allocation
-/// on Windows.
-pub const GetEnvResult = struct {
-    value: []const u8,
-
-    pub fn deinit(self: GetEnvResult, alloc: Allocator) void {
-        switch (builtin.os.tag) {
-            .windows => alloc.free(self.value),
-            else => {},
-        }
-    }
-};
-
-/// Gets the value of an environment variable, or null if not found.
-/// This will allocate on Windows but not on other platforms. The returned
-/// value should have deinit called to do the proper cleanup no matter what
-/// platform you are on.
-pub fn getenv(alloc: Allocator, key: []const u8) Error!?GetEnvResult {
-    return switch (builtin.os.tag) {
-        // Non-Windows doesn't need to allocate
-        else => if (posix.getenv(key)) |v| .{ .value = v } else null,
-
-        // Windows needs to allocate
-        .windows => if (std.process.getEnvVarOwned(alloc, key)) |v| .{
-            .value = v,
-        } else |err| switch (err) {
-            error.EnvironmentVariableNotFound => null,
-            error.InvalidWtf8 => null,
-            else => |e| e,
-        },
-    };
-}
-
-/// Gets the value of an environment variable. Returns null if not found or the
-/// value is empty. This will allocate on Windows but not on other platforms.
-/// The returned value should have deinit called to do the proper cleanup no
-/// matter what platform you are on.
-pub fn getenvNotEmpty(alloc: Allocator, key: []const u8) !?GetEnvResult {
-    const result_ = try getenv(alloc, key);
-    if (result_) |result| {
-        if (result.value.len == 0) {
-            result.deinit(alloc);
-            return null;
-        }
-    }
-    return result_;
-}
-
-pub fn setenv(key: [:0]const u8, value: [:0]const u8) c_int {
-    return switch (builtin.os.tag) {
-        .windows => c._putenv_s(key.ptr, value.ptr),
-        else => c.setenv(key.ptr, value.ptr, 1),
-    };
-}
-
-pub fn unsetenv(key: [:0]const u8) c_int {
-    return switch (builtin.os.tag) {
-        .windows => c._putenv_s(key.ptr, ""),
-        else => c.unsetenv(key.ptr),
-    };
-}
-
-const c = struct {
-    // POSIX
-    extern "c" fn setenv(name: ?[*]const u8, value: ?[*]const u8, overwrite: c_int) c_int;
-    extern "c" fn unsetenv(name: ?[*]const u8) c_int;
-
-    // Windows
-    extern "c" fn _putenv_s(varname: ?[*]const u8, value_string: ?[*]const u8) c_int;
-};
-
-test "appendEnv empty" {
-    const testing = std.testing;
-    const alloc = testing.allocator;
-
-    const result = try appendEnv(alloc, "", "foo");
-    defer alloc.free(result);
-    try testing.expectEqualStrings(result, "foo");
-}
-
-test "appendEnv existing" {
-    const testing = std.testing;
-    const alloc = testing.allocator;
-
-    const result = try appendEnv(alloc, "a:b", "foo");
-    defer alloc.free(result);
-    if (builtin.os.tag == .windows) {
-        try testing.expectEqualStrings(result, "a:b;foo");
-    } else {
-        try testing.expectEqualStrings(result, "a:b:foo");
-    }
-}
-
-test "prependEnv empty" {
-    const testing = std.testing;
-    const alloc = testing.allocator;
-
-    const result = try prependEnv(alloc, "", "foo");
-    defer alloc.free(result);
-    try testing.expectEqualStrings(result, "foo");
-}
-
-test "prependEnv existing" {
-    const testing = std.testing;
-    const alloc = testing.allocator;
-
-    const result = try prependEnv(alloc, "a:b", "foo");
-    defer alloc.free(result);
-    if (builtin.os.tag == .windows) {
-        try testing.expectEqualStrings(result, "foo;a:b");
-    } else {
-        try testing.expectEqualStrings(result, "foo:a:b");
-    }
-}
diff --git a/src/os/file.zig b/src/os/file.zig
index 6007ae495..3c170b467 100644
--- a/src/os/file.zig
+++ b/src/os/file.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const builtin = @import("builtin");
+const global = @import("../global.zig");
 const posix = std.posix;
 const windows = @import("windows.zig");
 
@@ -63,7 +64,7 @@ pub fn restoreMaxFiles(lim: rlimit) void {
 /// POSIX this returns `$TMPDIR`/`$TMP` (or `"/tmp"` as a fallback)
 /// without allocating. Always pair with `freeTmpDir` to release any
 /// allocation.
-pub fn allocTmpDir(allocator: std.mem.Allocator) std.mem.Allocator.Error![]const u8 {
+pub fn allocTmpDir(allocator: std.mem.Allocator, environ: std.process.Environ) std.mem.Allocator.Error![]const u8 {
     if (builtin.os.tag == .windows) {
         // GetTempPathW guarantees the result fits in MAX_PATH+1.
         var buf: [windows.MAX_PATH + 1:0]u16 = undefined;
@@ -81,7 +82,7 @@ pub fn allocTmpDir(allocator: std.mem.Allocator) std.mem.Allocator.Error![]const
         }
         return allocator.dupe(u8, "C:\\Windows\\Temp");
     }
-    const tmpdir = posix.getenv("TMPDIR") orelse posix.getenv("TMP") orelse return "/tmp";
+    const tmpdir = environ.getPosix("TMPDIR") orelse environ.getPosix("TMP") orelse return "/tmp";
     return std.mem.trimEnd(u8, tmpdir, &.{std.fs.path.sep});
 }
 
@@ -107,7 +108,7 @@ pub const random_basename_len = b64_encoder.calcSize(random_basename_bytes);
 pub fn randomBasename(buf: []u8) RandomBasenameError![]const u8 {
     if (buf.len < random_basename_len) return error.BufferTooSmall;
     var rand_buf: [random_basename_bytes]u8 = undefined;
-    std.crypto.random.bytes(&rand_buf);
+    global.io().random(&rand_buf);
     return b64_encoder.encode(buf[0..random_basename_len], &rand_buf);
 }
 
@@ -121,14 +122,12 @@ pub fn randomTmpPath(
     allocator: std.mem.Allocator,
     prefix: []const u8,
 ) std.mem.Allocator.Error![]u8 {
-    const tmp_dir = try allocTmpDir(allocator);
-    defer freeTmpDir(allocator, tmp_dir);
     var name_buf: [random_basename_len]u8 = undefined;
     const basename = randomBasename(&name_buf) catch unreachable;
     return std.fmt.allocPrint(
         allocator,
         "{s}{c}{s}{s}",
-        .{ tmp_dir, std.fs.path.sep, prefix, basename },
+        .{ global.tmpDirPath(), std.fs.path.sep, prefix, basename },
     );
 }
 
diff --git a/src/os/flatpak.zig b/src/os/flatpak.zig
index 44f820adc..15c619dee 100644
--- a/src/os/flatpak.zig
+++ b/src/os/flatpak.zig
@@ -2,7 +2,8 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const builtin = @import("builtin");
 const posix = std.posix;
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 
 const log = std.log.scoped(.flatpak);
 
@@ -10,7 +11,10 @@ const log = std.log.scoped(.flatpak);
 pub fn isFlatpak() bool {
     // If we're not on Linux then we'll make this comptime false.
     if (comptime builtin.os.tag != .linux) return false;
-    return if (std.fs.accessAbsolute("/.flatpak-info", .{})) true else |_| false;
+    return if (std.Io.Dir.accessAbsolute(global.io(), "/.flatpak-info", .{}))
+        true
+    else |_|
+        false;
 }
 
 /// A struct to help execute commands on the host via the
@@ -28,11 +32,8 @@ pub fn isFlatpak() bool {
 /// Requires GIO, GLib to be available and linked.
 pub const FlatpakHostCommand = struct {
     const fd_t = posix.fd_t;
-    const EnvMap = std.process.EnvMap;
-    const c = @cImport({
-        @cInclude("gio/gio.h");
-        @cInclude("gio/gunixfdlist.h");
-    });
+    const EnvMap = std.process.Environ.Map;
+    const gio_c = @import("gio_c");
     /// Flags for HostCommand method
     ///
     /// Ref: https://docs.flatpak.org/en/latest/libflatpak-api-reference.html#gdbus-method-org-freedesktop-Flatpak-Development.HostCommand
@@ -65,8 +66,8 @@ pub const FlatpakHostCommand = struct {
     /// State of the process. This is updated by the dedicated thread it
     /// runs in and is protected by the given lock and condition variable.
     state: State = .{ .init = {} },
-    state_mutex: std.Thread.Mutex = .{},
-    state_cv: std.Thread.Condition = .{},
+    state_mutex: std.Io.Mutex = .init,
+    state_cv: std.Io.Condition = .init,
 
     /// State the process is in. This can't be inspected directly, you
     /// must use getters on the struct to get access.
@@ -84,8 +85,8 @@ pub const FlatpakHostCommand = struct {
             pid: u32,
             loop_xev: ?*xev.Loop,
             completion: ?*Completion,
-            subscription: c.guint,
-            loop: *c.GMainLoop,
+            subscription: gio_c.guint,
+            loop: *gio_c.GMainLoop,
         },
 
         /// Process exited
@@ -120,14 +121,14 @@ pub const FlatpakHostCommand = struct {
     /// Precondition: The self pointer MUST be stable.
     pub fn spawn(self: *FlatpakHostCommand, alloc: Allocator) !u32 {
         const thread = try std.Thread.spawn(.{}, threadMain, .{ self, alloc });
-        thread.setName("flatpak-host-command") catch {};
+        thread.setName(global.io(), "flatpak-host-command") catch {};
         // We don't track this thread, it will terminate on its own on command exit
         thread.detach();
 
         // Wait for the process to start or error.
-        self.state_mutex.lock();
-        defer self.state_mutex.unlock();
-        while (self.state == .init) self.state_cv.wait(&self.state_mutex);
+        self.state_mutex.lockUncancelable(global.io());
+        defer self.state_mutex.unlock(global.io());
+        while (self.state == .init) self.state_cv.waitUncancelable(global.io(), &self.state_mutex);
 
         return switch (self.state) {
             .init => unreachable,
@@ -140,8 +141,8 @@ pub const FlatpakHostCommand = struct {
     /// Wait for the process to end and return the exit status. This
     /// can only be called ONCE. Once this returns, the state is reset.
     pub fn wait(self: *FlatpakHostCommand) !u8 {
-        self.state_mutex.lock();
-        defer self.state_mutex.unlock();
+        self.state_mutex.lockUncancelable(global.io());
+        defer self.state_mutex.unlock(global.io());
 
         while (true) {
             switch (self.state) {
@@ -150,12 +151,12 @@ pub const FlatpakHostCommand = struct {
                 .started => {},
                 .exited => |v| {
                     self.state = .{ .init = {} };
-                    self.state_cv.broadcast();
+                    self.state_cv.broadcast(global.io());
                     return v.status;
                 },
             }
 
-            self.state_cv.wait(&self.state_mutex);
+            self.state_cv.waitUncancelable(global.io(), &self.state_mutex);
         }
     }
 
@@ -174,8 +175,8 @@ pub const FlatpakHostCommand = struct {
             r: WaitError!u8,
         ) void,
     ) void {
-        self.state_mutex.lock();
-        defer self.state_mutex.unlock();
+        self.state_mutex.lockUncancelable(global.io());
+        defer self.state_mutex.unlock(global.io());
 
         completion.* = .{
             .callback = (struct {
@@ -234,8 +235,8 @@ pub const FlatpakHostCommand = struct {
     /// command is not in the started state.
     pub fn signal(self: *FlatpakHostCommand, sig: u8, pg: bool) !void {
         const pid = pid: {
-            self.state_mutex.lock();
-            defer self.state_mutex.unlock();
+            self.state_mutex.lockUncancelable(global.io());
+            defer self.state_mutex.unlock(global.io());
             switch (self.state) {
                 .started => |v| break :pid v.pid,
                 else => return,
@@ -243,29 +244,29 @@ pub const FlatpakHostCommand = struct {
         };
 
         // Get our bus connection.
-        var g_err: ?*c.GError = null;
-        defer if (g_err) |ptr| c.g_error_free(ptr);
-        const bus = c.g_bus_get_sync(c.G_BUS_TYPE_SESSION, null, &g_err) orelse {
+        var g_err: ?*gio_c.GError = null;
+        defer if (g_err) |ptr| gio_c.g_error_free(ptr);
+        const bus = gio_c.g_bus_get_sync(gio_c.G_BUS_TYPE_SESSION, null, &g_err) orelse {
             log.warn("signal error getting bus: {s}", .{g_err.?.*.message});
             return Error.FlatpakSetupFail;
         };
-        defer c.g_object_unref(bus);
+        defer gio_c.g_object_unref(bus);
 
-        const reply = c.g_dbus_connection_call_sync(
+        const reply = gio_c.g_dbus_connection_call_sync(
             bus,
             "org.freedesktop.Flatpak",
             "/org/freedesktop/Flatpak/Development",
             "org.freedesktop.Flatpak.Development",
             "HostCommandSignal",
-            c.g_variant_new(
+            gio_c.g_variant_new(
                 "(uub)",
                 pid,
                 sig,
                 @as(c_int, @intCast(@intFromBool(pg))),
             ),
-            c.G_VARIANT_TYPE("()"),
-            c.G_DBUS_CALL_FLAGS_NONE,
-            c.G_MAXINT,
+            gio_c.G_VARIANT_TYPE("()"),
+            gio_c.G_DBUS_CALL_FLAGS_NONE,
+            gio_c.G_MAXINT,
             null,
             &g_err,
         );
@@ -273,31 +274,31 @@ pub const FlatpakHostCommand = struct {
             log.warn("signal send error: {s}", .{g_err.?.*.message});
             return;
         }
-        defer c.g_variant_unref(reply);
+        defer gio_c.g_variant_unref(reply);
     }
 
     fn threadMain(self: *FlatpakHostCommand, alloc: Allocator) void {
         // Create a new thread-local context so that all our sources go
         // to this context and we can run our loop correctly.
-        const ctx = c.g_main_context_new();
-        defer c.g_main_context_unref(ctx);
-        c.g_main_context_push_thread_default(ctx);
-        defer c.g_main_context_pop_thread_default(ctx);
+        const ctx = gio_c.g_main_context_new();
+        defer gio_c.g_main_context_unref(ctx);
+        gio_c.g_main_context_push_thread_default(ctx);
+        defer gio_c.g_main_context_pop_thread_default(ctx);
 
         // Get our loop for the current thread
-        const loop = c.g_main_loop_new(ctx, 1).?;
-        defer c.g_main_loop_unref(loop);
+        const loop = gio_c.g_main_loop_new(ctx, 1).?;
+        defer gio_c.g_main_loop_unref(loop);
 
         // Get our bus connection. This has to remain active until we exit
         // the thread otherwise our signals won't be called.
-        var g_err: ?*c.GError = null;
-        defer if (g_err) |ptr| c.g_error_free(ptr);
-        const bus = c.g_bus_get_sync(c.G_BUS_TYPE_SESSION, null, &g_err) orelse {
+        var g_err: ?*gio_c.GError = null;
+        defer if (g_err) |ptr| gio_c.g_error_free(ptr);
+        const bus = gio_c.g_bus_get_sync(gio_c.G_BUS_TYPE_SESSION, null, &g_err) orelse {
             log.warn("spawn error getting bus: {s}", .{g_err.?.*.message});
             self.updateState(.{ .err = {} });
             return;
         };
-        defer c.g_object_unref(bus);
+        defer gio_c.g_object_unref(bus);
 
         // Spawn the command first. This will setup all our IO.
         self.start(alloc, bus, loop) catch |err| {
@@ -307,7 +308,7 @@ pub const FlatpakHostCommand = struct {
         };
 
         // Run the event loop. It quits in the exit callback.
-        c.g_main_loop_run(loop);
+        gio_c.g_main_loop_run(loop);
     }
 
     /// Start the command. This will start the host command and set the
@@ -318,47 +319,47 @@ pub const FlatpakHostCommand = struct {
     fn start(
         self: *FlatpakHostCommand,
         alloc: Allocator,
-        bus: *c.GDBusConnection,
-        loop: *c.GMainLoop,
+        bus: *gio_c.GDBusConnection,
+        loop: *gio_c.GMainLoop,
     ) !void {
-        var err: ?*c.GError = null;
-        defer if (err) |ptr| c.g_error_free(ptr);
+        var err: ?*gio_c.GError = null;
+        defer if (err) |ptr| gio_c.g_error_free(ptr);
         var arena_allocator = std.heap.ArenaAllocator.init(alloc);
         defer arena_allocator.deinit();
         const arena = arena_allocator.allocator();
 
         // Our list of file descriptors that we need to send to the process.
-        const fd_list = c.g_unix_fd_list_new();
-        defer c.g_object_unref(fd_list);
-        if (c.g_unix_fd_list_append(fd_list, self.stdin, &err) < 0) {
+        const fd_list = gio_c.g_unix_fd_list_new();
+        defer gio_c.g_object_unref(fd_list);
+        if (gio_c.g_unix_fd_list_append(fd_list, self.stdin, &err) < 0) {
             log.warn("error adding fd: {s}", .{err.?.*.message});
             return Error.FlatpakSetupFail;
         }
-        if (c.g_unix_fd_list_append(fd_list, self.stdout, &err) < 0) {
+        if (gio_c.g_unix_fd_list_append(fd_list, self.stdout, &err) < 0) {
             log.warn("error adding fd: {s}", .{err.?.*.message});
             return Error.FlatpakSetupFail;
         }
-        if (c.g_unix_fd_list_append(fd_list, self.stderr, &err) < 0) {
+        if (gio_c.g_unix_fd_list_append(fd_list, self.stderr, &err) < 0) {
             log.warn("error adding fd: {s}", .{err.?.*.message});
             return Error.FlatpakSetupFail;
         }
 
         // Build our arguments for the file descriptors.
-        const fd_builder = c.g_variant_builder_new(c.G_VARIANT_TYPE("a{uh}"));
-        defer c.g_variant_builder_unref(fd_builder);
-        c.g_variant_builder_add(fd_builder, "{uh}", @as(c_int, 0), self.stdin);
-        c.g_variant_builder_add(fd_builder, "{uh}", @as(c_int, 1), self.stdout);
-        c.g_variant_builder_add(fd_builder, "{uh}", @as(c_int, 2), self.stderr);
+        const fd_builder = gio_c.g_variant_builder_new(gio_c.G_VARIANT_TYPE("a{uh}"));
+        defer gio_c.g_variant_builder_unref(fd_builder);
+        gio_c.g_variant_builder_add(fd_builder, "{uh}", @as(c_int, 0), self.stdin);
+        gio_c.g_variant_builder_add(fd_builder, "{uh}", @as(c_int, 1), self.stdout);
+        gio_c.g_variant_builder_add(fd_builder, "{uh}", @as(c_int, 2), self.stderr);
 
         // Build our env vars
-        const env_builder = c.g_variant_builder_new(c.G_VARIANT_TYPE("a{ss}"));
-        defer c.g_variant_builder_unref(env_builder);
+        const env_builder = gio_c.g_variant_builder_new(gio_c.G_VARIANT_TYPE("a{ss}"));
+        defer gio_c.g_variant_builder_unref(env_builder);
         if (self.env) |env| {
             var it = env.iterator();
             while (it.next()) |pair| {
                 const key = try arena.dupeZ(u8, pair.key_ptr.*);
                 const value = try arena.dupeZ(u8, pair.value_ptr.*);
-                c.g_variant_builder_add(env_builder, "{ss}", key.ptr, value.ptr);
+                gio_c.g_variant_builder_add(env_builder, "{ss}", key.ptr, value.ptr);
             }
         }
 
@@ -373,26 +374,26 @@ pub const FlatpakHostCommand = struct {
         // Get the cwd in case we don't have ours set. A small optimization
         // would be to do this only if we need it but this isn't a
         // common code path.
-        const g_cwd = c.g_get_current_dir();
-        defer c.g_free(g_cwd);
+        const g_cwd = gio_c.g_get_current_dir();
+        defer gio_c.g_free(g_cwd);
 
         // Terminate session if Ghostty drops off the bus (e.g. due to crashes)
         const flags: Flags = .{ .watch_bus = true };
 
         // The params for our RPC call
-        const params = c.g_variant_new(
+        const params = gio_c.g_variant_new(
             "(^ay^aay@a{uh}@a{ss}u)",
             @as(*const anyopaque, if (self.cwd) |*cwd| cwd.ptr else g_cwd),
             args.ptr,
-            c.g_variant_builder_end(fd_builder),
-            c.g_variant_builder_end(env_builder),
+            gio_c.g_variant_builder_end(fd_builder),
+            gio_c.g_variant_builder_end(env_builder),
             @as(c_uint, @bitCast(flags)),
         );
-        _ = c.g_variant_ref_sink(params); // take ownership
-        defer c.g_variant_unref(params);
+        _ = gio_c.g_variant_ref_sink(params); // take ownership
+        defer gio_c.g_variant_unref(params);
 
         // Subscribe to exit notifications
-        const subscription_id = c.g_dbus_connection_signal_subscribe(
+        const subscription_id = gio_c.g_dbus_connection_signal_subscribe(
             bus,
             "org.freedesktop.Flatpak",
             "org.freedesktop.Flatpak.Development",
@@ -404,19 +405,19 @@ pub const FlatpakHostCommand = struct {
             self,
             null,
         );
-        errdefer c.g_dbus_connection_signal_unsubscribe(bus, subscription_id);
+        errdefer gio_c.g_dbus_connection_signal_unsubscribe(bus, subscription_id);
 
         // Go!
-        const reply = c.g_dbus_connection_call_with_unix_fd_list_sync(
+        const reply = gio_c.g_dbus_connection_call_with_unix_fd_list_sync(
             bus,
             "org.freedesktop.Flatpak",
             "/org/freedesktop/Flatpak/Development",
             "org.freedesktop.Flatpak.Development",
             "HostCommand",
             params,
-            c.G_VARIANT_TYPE("(u)"),
-            c.G_DBUS_CALL_FLAGS_NONE,
-            c.G_MAXINT,
+            gio_c.G_VARIANT_TYPE("(u)"),
+            gio_c.G_DBUS_CALL_FLAGS_NONE,
+            gio_c.G_MAXINT,
             fd_list,
             null,
             null,
@@ -425,10 +426,10 @@ pub const FlatpakHostCommand = struct {
             log.warn("Flatpak.HostCommand failed: {s}", .{err.?.*.message});
             return Error.FlatpakRPCFail;
         };
-        defer c.g_variant_unref(reply);
+        defer gio_c.g_variant_unref(reply);
 
         var pid: u32 = 0;
-        c.g_variant_get(reply, "(u)", &pid);
+        gio_c.g_variant_get(reply, "(u)", &pid);
         log.debug("HostCommand started pid={} subscription={}", .{
             pid,
             subscription_id,
@@ -447,31 +448,31 @@ pub const FlatpakHostCommand = struct {
 
     /// Helper to update the state and notify waiters via the cv.
     fn updateState(self: *FlatpakHostCommand, state: State) void {
-        self.state_mutex.lock();
-        defer self.state_mutex.unlock();
-        defer self.state_cv.broadcast();
+        self.state_mutex.lockUncancelable(global.io());
+        defer self.state_mutex.unlock(global.io());
+        defer self.state_cv.broadcast(global.io());
         self.state = state;
     }
 
     fn onExit(
-        bus: ?*c.GDBusConnection,
+        bus: ?*gio_c.GDBusConnection,
         _: [*c]const u8,
         _: [*c]const u8,
         _: [*c]const u8,
         _: [*c]const u8,
-        params: ?*c.GVariant,
+        params: ?*gio_c.GVariant,
         ud: ?*anyopaque,
     ) callconv(.c) void {
         const self = @as(*FlatpakHostCommand, @ptrCast(@alignCast(ud)));
         const state = state: {
-            self.state_mutex.lock();
-            defer self.state_mutex.unlock();
+            self.state_mutex.lockUncancelable(global.io());
+            defer self.state_mutex.unlock(global.io());
             break :state self.state.started;
         };
 
         var pid: u32 = 0;
         var exit_status_raw: u32 = 0;
-        c.g_variant_get(params.?, "(uu)", &pid, &exit_status_raw);
+        gio_c.g_variant_get(params.?, "(uu)", &pid, &exit_status_raw);
         if (state.pid != pid) return;
 
         const exit_status = posix.W.EXITSTATUS(exit_status_raw);
@@ -510,10 +511,10 @@ pub const FlatpakHostCommand = struct {
         log.debug("HostCommand exited pid={} status={}", .{ pid, exit_status });
 
         // We're done now, so we can unsubscribe
-        c.g_dbus_connection_signal_unsubscribe(bus.?, state.subscription);
+        gio_c.g_dbus_connection_signal_unsubscribe(bus.?, state.subscription);
 
         // We are also done with our loop so we can exit.
-        c.g_main_loop_quit(state.loop);
+        gio_c.g_main_loop_quit(state.loop);
     }
 
     fn noopCallback(_: ?*anyopaque, _: *xev.Loop, _: *Completion, _: WaitError!u8) void {}
diff --git a/src/os/homedir.zig b/src/os/homedir.zig
index 9e0420f4a..4972621eb 100644
--- a/src/os/homedir.zig
+++ b/src/os/homedir.zig
@@ -1,7 +1,7 @@
 const std = @import("std");
 const builtin = @import("builtin");
 const passwd = @import("passwd.zig");
-const posix = std.posix;
+const global = @import("../global.zig");
 const objc = @import("objc");
 
 const Error = error{
@@ -11,10 +11,10 @@ const Error = error{
 
 /// Determine the home directory for the currently executing user. This
 /// is generally an expensive process so the value should be cached.
-pub inline fn home(buf: []u8) !?[]const u8 {
+pub inline fn home(environ_map: *const std.process.Environ.Map, buf: []u8) !?[]const u8 {
     return switch (builtin.os.tag) {
-        .linux, .freebsd, .macos => try homeUnix(buf),
-        .windows => try homeWindows(buf),
+        .linux, .freebsd, .macos => try homeUnix(environ_map, buf),
+        .windows => homeWindows(environ_map, buf) catch return error.BufferTooSmall,
 
         // iOS doesn't have a user-writable home directory
         .ios => null,
@@ -23,9 +23,9 @@ pub inline fn home(buf: []u8) !?[]const u8 {
     };
 }
 
-fn homeUnix(buf: []u8) !?[]const u8 {
+fn homeUnix(environ_map: *const std.process.Environ.Map, buf: []u8) !?[]const u8 {
     // First: if we have a HOME env var, then we use that.
-    if (posix.getenv("HOME")) |result| {
+    if (environ_map.get("HOME")) |result| {
         if (buf.len < result.len) return Error.BufferTooSmall;
         @memcpy(buf[0..result.len], result);
         return buf[0..result.len];
@@ -60,13 +60,13 @@ fn homeUnix(buf: []u8) !?[]const u8 {
 
     // If all else fails, have the shell tell us...
     fba.reset();
-    const run = try std.process.Child.run(.{
-        .allocator = fba.allocator(),
+    const run = try std.process.run(fba.allocator(), global.io(), .{
         .argv = &[_][]const u8{ "/bin/sh", "-c", "cd && pwd" },
-        .max_output_bytes = fba.buffer.len / 2,
+        .stdout_limit = .limited(fba.buffer.len / 2),
+        .stderr_limit = .limited(fba.buffer.len / 2),
     });
 
-    if (run.term == .Exited and run.term.Exited == 0) {
+    if (run.term == .exited and run.term.exited == 0) {
         const result = trimSpace(run.stdout);
         if (buf.len < result.len) return Error.BufferTooSmall;
         @memcpy(buf[0..result.len], result);
@@ -76,33 +76,11 @@ fn homeUnix(buf: []u8) !?[]const u8 {
     return null;
 }
 
-fn homeWindows(buf: []u8) !?[]const u8 {
-    const drive_len = blk: {
-        var fba_instance = std.heap.FixedBufferAllocator.init(buf);
-        const fba = fba_instance.allocator();
-        const drive = std.process.getEnvVarOwned(fba, "HOMEDRIVE") catch |err| switch (err) {
-            error.OutOfMemory => return Error.BufferTooSmall,
-            error.InvalidWtf8, error.EnvironmentVariableNotFound => return null,
-        };
-        // could shift the contents if this ever happens
-        if (drive.ptr != buf.ptr) @panic("codebug");
-        break :blk drive.len;
-    };
-
-    const path_len = blk: {
-        const path_buf = buf[drive_len..];
-        var fba_instance = std.heap.FixedBufferAllocator.init(buf[drive_len..]);
-        const fba = fba_instance.allocator();
-        const homepath = std.process.getEnvVarOwned(fba, "HOMEPATH") catch |err| switch (err) {
-            error.OutOfMemory => return Error.BufferTooSmall,
-            error.InvalidWtf8, error.EnvironmentVariableNotFound => return null,
-        };
-        // could shift the contents if this ever happens
-        if (homepath.ptr != path_buf.ptr) @panic("codebug");
-        break :blk homepath.len;
-    };
-
-    return buf[0 .. drive_len + path_len];
+fn homeWindows(environ_map: *const std.process.Environ.Map, buf: []u8) !?[]const u8 {
+    var writer: std.Io.Writer = .fixed(buf);
+    _ = try writer.write(environ_map.get("HOMEDRIVE") orelse return null);
+    _ = try writer.write(environ_map.get("HOMEPATH") orelse return null);
+    return writer.buffered();
 }
 
 fn trimSpace(input: []const u8) []const u8 {
@@ -119,9 +97,9 @@ pub const ExpandError = error{
 ///
 /// Errors if `home` fails or if the size of the expanded path is larger
 /// than `buf.len`.
-pub fn expandHome(path: []const u8, buf: []u8) ExpandError![]const u8 {
+pub fn expandHome(environ_map: *const std.process.Environ.Map, path: []const u8, buf: []u8) ExpandError![]const u8 {
     return switch (builtin.os.tag) {
-        .linux, .freebsd, .macos => try expandHomeUnix(path, buf),
+        .linux, .freebsd, .macos => try expandHomeUnix(environ_map, path, buf),
 
         // `~/` is not an idiom generally used on Windows
         .windows => return path,
@@ -133,9 +111,9 @@ pub fn expandHome(path: []const u8, buf: []u8) ExpandError![]const u8 {
     };
 }
 
-fn expandHomeUnix(path: []const u8, buf: []u8) ExpandError![]const u8 {
+fn expandHomeUnix(environ_map: *const std.process.Environ.Map, path: []const u8, buf: []u8) ExpandError![]const u8 {
     if (!std.mem.startsWith(u8, path, "~/")) return path;
-    const home_dir: []const u8 = if (home(buf)) |home_|
+    const home_dir: []const u8 = if (home(environ_map, buf)) |home_|
         home_ orelse return error.HomeDetectionFailed
     else |_|
         return error.HomeDetectionFailed;
@@ -153,27 +131,30 @@ test "expandHomeUnix" {
 
     const testing = std.testing;
     const allocator = testing.allocator;
+    var environ_map = try testing.environ.createMap(testing.allocator);
+    defer environ_map.deinit();
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const home_dir = try expandHomeUnix("~/", &buf);
+    const home_dir = try expandHomeUnix(&environ_map, "~/", &buf);
     // Joining the home directory `~` with the path `/`
     // the result should end with a separator here. (e.g. `/home/user/`)
     try testing.expect(home_dir[home_dir.len - 1] == std.fs.path.sep);
 
-    const downloads = try expandHomeUnix("~/Downloads/shader.glsl", &buf);
+    const downloads = try expandHomeUnix(&environ_map, "~/Downloads/shader.glsl", &buf);
     const expected_downloads = try std.mem.concat(allocator, u8, &[_][]const u8{ home_dir, "Downloads/shader.glsl" });
     defer allocator.free(expected_downloads);
     try testing.expectEqualStrings(expected_downloads, downloads);
 
-    try testing.expectEqualStrings("~", try expandHomeUnix("~", &buf));
-    try testing.expectEqualStrings("~abc/", try expandHomeUnix("~abc/", &buf));
-    try testing.expectEqualStrings("/home/user", try expandHomeUnix("/home/user", &buf));
-    try testing.expectEqualStrings("", try expandHomeUnix("", &buf));
+    try testing.expectEqualStrings("~", try expandHomeUnix(&environ_map, "~", &buf));
+    try testing.expectEqualStrings("~abc/", try expandHomeUnix(&environ_map, "~abc/", &buf));
+    try testing.expectEqualStrings("/home/user", try expandHomeUnix(&environ_map, "/home/user", &buf));
+    try testing.expectEqualStrings("", try expandHomeUnix(&environ_map, "", &buf));
 
     // Expect an error if the buffer is large enough to hold the home directory,
     // but not the expanded path
     var small_buf = try allocator.alloc(u8, home_dir.len);
     defer allocator.free(small_buf);
     try testing.expectError(error.BufferTooSmall, expandHomeUnix(
+        &environ_map,
         "~/Downloads",
         small_buf[0..],
     ));
@@ -181,9 +162,11 @@ test "expandHomeUnix" {
 
 test {
     const testing = std.testing;
+    var environ_map = try testing.environ.createMap(testing.allocator);
+    defer environ_map.deinit();
 
     var buf: [1024]u8 = undefined;
-    const result = try home(&buf);
+    const result = try home(&environ_map, &buf);
     try testing.expect(result != null);
     try testing.expect(result.?.len > 0);
 }
diff --git a/src/os/hostname.zig b/src/os/hostname.zig
index af9148fbf..45689e0b6 100644
--- a/src/os/hostname.zig
+++ b/src/os/hostname.zig
@@ -105,7 +105,7 @@ pub fn isLocal(hostname: []const u8) LocalHostnameValidationError!bool {
             const windows = @import("windows.zig");
             var buf: [256:0]u8 = undefined;
             var nSize: windows.DWORD = buf.len;
-            if (windows.exp.kernel32.GetComputerNameA(&buf, &nSize) == 0) return false;
+            if (windows.exp.kernel32.GetComputerNameA(&buf, &nSize) == windows.FALSE) return false;
             const ourHostname = buf[0..nSize];
             return std.mem.eql(u8, hostname, ourHostname);
         },
@@ -127,7 +127,8 @@ test "isLocal returns true when hostname is local" {
             const windows = @import("windows.zig");
             var buf: [256:0]u8 = undefined;
             var nSize: windows.DWORD = buf.len;
-            if (windows.exp.kernel32.GetComputerNameA(&buf, &nSize) == 0) return error.GetComputerNameFailed;
+            if (windows.exp.kernel32.GetComputerNameA(&buf, &nSize) == windows.FALSE)
+                return error.GetComputerNameFailed;
             const localHostname = buf[0..nSize];
             try std.testing.expect(try isLocal(localHostname));
         },
diff --git a/src/os/kernel_info.zig b/src/os/kernel_info.zig
index e57cc3047..60e6b49fd 100644
--- a/src/os/kernel_info.zig
+++ b/src/os/kernel_info.zig
@@ -1,15 +1,20 @@
 const std = @import("std");
 const builtin = @import("builtin");
+const global = @import("../global.zig");
 
 pub fn getKernelInfo(alloc: std.mem.Allocator) ?[]const u8 {
     if (comptime builtin.os.tag != .linux) return null;
     const path = "/proc/sys/kernel/osrelease";
-    var file = std.fs.openFileAbsolute(path, .{}) catch return null;
-    defer file.close();
+    var file = std.Io.Dir.openFileAbsolute(global.io(), path, .{}) catch return null;
+    defer file.close(global.io());
 
     // 128 bytes should be enough to hold the kernel information
-    const kernel_info = file.readToEndAlloc(alloc, 128) catch return null;
-    defer alloc.free(kernel_info);
+    var kernel_info_buf: [128]u8 = undefined;
+    const kernel_info = kernel_info_buf[0 .. file.readPositionalAll(
+        global.io(),
+        &kernel_info_buf,
+        0,
+    ) catch return null];
     return alloc.dupe(u8, std.mem.trim(u8, kernel_info, &std.ascii.whitespace)) catch return null;
 }
 
diff --git a/src/os/locale.zig b/src/os/locale.zig
index faba3bd29..ceb3c883c 100644
--- a/src/os/locale.zig
+++ b/src/os/locale.zig
@@ -9,13 +9,10 @@ const i18n = internal_os.i18n;
 const log = std.log.scoped(.os_locale);
 
 /// Ensure that the locale is set.
-pub fn ensureLocale(alloc: std.mem.Allocator) !void {
-    assert(builtin.link_libc);
-
-    // Get our LANG env var. We use this many times but we also need
-    // the original value later.
-    const lang = try internal_os.getenv(alloc, "LANG");
-    defer if (lang) |v| v.deinit(alloc);
+pub fn ensureLocale() !void {
+    // This does a lot of in-process mutation of the environment and can't be
+    // run in a test as a result.
+    assert(!builtin.is_test);
 
     // On macOS, pre-populate the LANG env var with system preferences.
     // When launching the .app, LANG is not set so we must query it from the
@@ -23,7 +20,8 @@ pub fn ensureLocale(alloc: std.mem.Allocator) !void {
     // process.
     if (comptime builtin.target.os.tag.isDarwin()) {
         // Set the lang if it is not set or if its empty.
-        if (lang == null or lang.?.value.len == 0) {
+        const lang = std.posix.system.getenv("LANG");
+        if (lang == null or lang.?[0] == 0) {
             setLangFromCocoa();
         }
     }
@@ -34,16 +32,29 @@ pub fn ensureLocale(alloc: std.mem.Allocator) !void {
         return;
     }
 
+    if (builtin.os.tag == .windows) {
+        // Exit early for Windows.
+        //
+        // NOTE: There currently is no official Windows version of Ghostty,
+        // either by way of an official Windows port or through use of
+        // libghostty-internal. As such this function is likely unused on those
+        // platforms, so this serves as a TODO stub to support more robust
+        // locale support on Windows. setlocale on Windows sets an
+        // "implementation-defined native environment" with an empty string, so
+        // we are currently just doing best-effort for now.
+        log.info("TODO: setlocale failed on Windows, implement better fallbacks", .{});
+        return;
+    }
+
     // setlocale failed. This is probably because the LANG env var is
     // invalid. Try to set it without the LANG var set to use the system
     // default.
-    if ((try internal_os.getenv(alloc, "LANG"))) |old_lang| {
-        defer old_lang.deinit(alloc);
-        if (old_lang.value.len > 0) {
+    if (std.posix.system.getenv("LANG")) |lang| {
+        if (lang[0] != 0) {
             // We don't need to do both of these things but we do them
             // both to be sure that lang is either empty or unset completely.
-            _ = internal_os.setenv("LANG", "");
-            _ = internal_os.unsetenv("LANG");
+            _ = setenv("LANG", "", 1);
+            _ = unsetenv("LANG");
 
             if (setlocale(LC_ALL, "")) |v| {
                 log.info("setlocale after unset lang result={s}", .{v});
@@ -59,7 +70,7 @@ pub fn ensureLocale(alloc: std.mem.Allocator) !void {
     // Failure again... fallback to en_US.UTF-8
     log.warn("setlocale failed with LANG and system default. Falling back to en_US.UTF-8", .{});
     if (setlocale(LC_ALL, "en_US.UTF-8")) |v| {
-        _ = internal_os.setenv("LANG", "en_US.UTF-8");
+        _ = setenv("LANG", "en_US.UTF-8", 1);
         log.info("setlocale default result={s}", .{v});
         return;
     } else log.warn("setlocale failed even with the fallback, uncertain results", .{});
@@ -106,7 +117,7 @@ fn setLangFromCocoa() void {
         log.info("detected system locale={s}", .{env_value});
 
         // Set it onto our environment
-        if (internal_os.setenv("LANG", env_value) < 0) {
+        if (setenv("LANG", @ptrCast(env_value), 1) < 0) {
             log.warn("error setting locale env var", .{});
             return;
         }
@@ -129,7 +140,7 @@ fn setLangFromCocoa() void {
             "setting LANGUAGE from preferred languages value={s}",
             .{pref},
         );
-        _ = internal_os.setenv("LANGUAGE", pref);
+        _ = setenv("LANGUAGE", @ptrCast(pref), 1);
     }
 }
 
@@ -156,8 +167,7 @@ fn preferredLanguageFromCocoa(
     buf: []u8,
     NSLocale: objc.Class,
 ) error{NoSpaceLeft}!?[:0]const u8 {
-    var fbs = std.io.fixedBufferStream(buf);
-    const writer = fbs.writer();
+    var writer: std.Io.Writer = .fixed(buf);
 
     // We need to get our app's preferred languages. These may not
     // match the system locale (NSLocale.currentLocale).
@@ -180,7 +190,7 @@ fn preferredLanguageFromCocoa(
         };
 
         // Append our separator if we have any previous languages
-        if (fbs.pos > 0) {
+        if (writer.end > 0) {
             _ = writer.writeByte(':') catch
                 return error.NoSpaceLeft;
         }
@@ -188,10 +198,10 @@ fn preferredLanguageFromCocoa(
         // Apple languages are in BCP-47 format, and we need to
         // canonicalize them to the POSIX format.
         const canon = try i18n.canonicalizeLocale(
-            fbs.buffer[fbs.pos..],
+            writer.buffer[writer.end..],
             c_str,
         );
-        fbs.seekBy(@intCast(canon.len)) catch unreachable;
+        writer.end += canon.len;
 
         // The canonicalized locale never contains the encoding and
         // all of our translations require UTF-8 so we add that.
@@ -199,14 +209,14 @@ fn preferredLanguageFromCocoa(
     }
 
     // If we had no preferred languages then we return nothing.
-    if (fbs.pos == 0) return null;
+    if (writer.end == 0) return null;
 
     // Null terminate it
     _ = writer.writeByte(0) catch return error.NoSpaceLeft;
 
     // Get our slice, this won't be null terminated so we have to
     // reslice it with the null terminator.
-    const slice = fbs.getWritten();
+    const slice = writer.buffered();
     return slice[0 .. slice.len - 1 :0];
 }
 
@@ -217,3 +227,6 @@ const locale_t = c.locale_t;
 const setlocale = c.setlocale;
 const newlocale = c.newlocale;
 const freelocale = c.freelocale;
+
+extern "c" fn setenv(name: ?[*]const u8, value: ?[*]const u8, overwrite: c_int) c_int;
+extern "c" fn unsetenv(name: ?[*]const u8) c_int;
diff --git a/src/os/mach.zig b/src/os/mach.zig
index 4477bd128..5f5a3ed8f 100644
--- a/src/os/mach.zig
+++ b/src/os/mach.zig
@@ -46,6 +46,9 @@ pub fn taggedPageAllocator(tag: VMTag) Allocator {
 /// This is based heavily on the Zig 0.15.2 PageAllocator implementation,
 /// with only the posix implementation. Zig 0.15.2 is MIT licensed.
 const TaggedPageAllocator = struct {
+    // Static local next_mmap_addr_hint since this has been removed from stdlib now
+    var next_mmap_addr_hint: ?[*]align(std.heap.page_size_min) u8 = null;
+
     pub const vtable: Allocator.VTable = .{
         .alloc = alloc,
         .resize = resize,
@@ -92,11 +95,11 @@ const TaggedPageAllocator = struct {
             aligned_len
         else
             mem.alignForward(usize, aligned_len + max_drop_len, page_size);
-        const hint = @atomicLoad(@TypeOf(std.heap.next_mmap_addr_hint), &std.heap.next_mmap_addr_hint, .unordered);
+        const hint = @atomicLoad(@TypeOf(next_mmap_addr_hint), &next_mmap_addr_hint, .unordered);
         const slice = std.posix.mmap(
             hint,
             overalloc_len,
-            std.posix.PROT.READ | std.posix.PROT.WRITE,
+            .{ .READ = true, .WRITE = true },
             .{ .TYPE = .PRIVATE, .ANONYMOUS = true },
             tag.make(),
             0,
@@ -110,7 +113,7 @@ const TaggedPageAllocator = struct {
         const remaining_len = overalloc_len - drop_len;
         if (remaining_len > aligned_len) std.posix.munmap(@alignCast(result_ptr[aligned_len..remaining_len]));
         const new_hint: [*]align(std.heap.page_size_min) u8 = @alignCast(result_ptr + aligned_len);
-        _ = @cmpxchgStrong(@TypeOf(std.heap.next_mmap_addr_hint), &std.heap.next_mmap_addr_hint, hint, new_hint, .monotonic, .monotonic);
+        _ = @cmpxchgStrong(@TypeOf(next_mmap_addr_hint), &next_mmap_addr_hint, hint, new_hint, .monotonic, .monotonic);
         return result_ptr;
     }
 
diff --git a/src/os/main.zig b/src/os/main.zig
index b30182740..7f9e12cf9 100644
--- a/src/os/main.zig
+++ b/src/os/main.zig
@@ -1,12 +1,11 @@
 //! The "os" package contains utilities for interfacing with the operating
-//! system. These aren't restricted to syscalls or low-level operations, but
+//! system. These aren't restricted to syscalls or low-level operations, butos/main.zig
 //! also OS-specific features and conventions.
 
 const builtin = @import("builtin");
 
 const dbus = @import("dbus.zig");
 const desktop = @import("desktop.zig");
-const env = @import("env.zig");
 const file = @import("file.zig");
 const flatpak = @import("flatpak.zig");
 const homedir = @import("homedir.zig");
@@ -19,7 +18,6 @@ const systemd = @import("systemd.zig");
 const kernel_info = @import("kernel_info.zig");
 
 // Namespaces
-pub const args = @import("args.zig");
 pub const cgroup = @import("cgroup.zig");
 pub const hostname = @import("hostname.zig");
 pub const i18n = @import("i18n.zig");
@@ -35,14 +33,6 @@ pub const uri = @import("uri.zig");
 // Functions and types
 pub const CFReleaseThread = @import("cf_release_thread.zig");
 pub const TempDir = @import("TempDir.zig");
-pub const GetEnvResult = env.GetEnvResult;
-pub const getEnvMap = env.getEnvMap;
-pub const appendEnv = env.appendEnv;
-pub const appendEnvAlways = env.appendEnvAlways;
-pub const prependEnv = env.prependEnv;
-pub const getenv = env.getenv;
-pub const setenv = env.setenv;
-pub const unsetenv = env.unsetenv;
 pub const launchedFromDesktop = desktop.launchedFromDesktop;
 pub const launchedByDbusActivation = dbus.launchedByDbusActivation;
 pub const launchedBySystemd = systemd.launchedBySystemd;
@@ -50,8 +40,6 @@ pub const desktopEnvironment = desktop.desktopEnvironment;
 pub const rlimit = file.rlimit;
 pub const fixMaxFiles = file.fixMaxFiles;
 pub const restoreMaxFiles = file.restoreMaxFiles;
-pub const allocTmpDir = file.allocTmpDir;
-pub const freeTmpDir = file.freeTmpDir;
 pub const randomTmpPath = file.randomTmpPath;
 pub const isFlatpak = flatpak.isFlatpak;
 pub const FlatpakHostCommand = flatpak.FlatpakHostCommand;
diff --git a/src/os/open.zig b/src/os/open.zig
index 86c3d76fd..806030fcd 100644
--- a/src/os/open.zig
+++ b/src/os/open.zig
@@ -3,6 +3,7 @@ const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
 const build_config = @import("../build_config.zig");
 const apprt = @import("../apprt.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.@"os-open");
 
@@ -15,71 +16,56 @@ const log = std.log.scoped(.@"os-open");
 /// way to open URLs. If you are implementing an apprt for Ghostty, you should
 /// consider doing something special-cased for your platform.
 pub fn open(
-    alloc: Allocator,
     kind: apprt.action.OpenUrl.Kind,
     url: []const u8,
 ) !void {
-    var exe: std.process.Child = switch (builtin.os.tag) {
-        .linux, .freebsd => .init(
-            &.{ "xdg-open", url },
-            alloc,
-        ),
-
-        .windows => .init(
-            &.{ "rundll32", "url.dll,FileProtocolHandler", url },
-            alloc,
-        ),
-
-        .macos => .init(
-            switch (kind) {
-                .text => &.{ "open", "-t", url },
-                .html, .unknown => &.{ "open", url },
-            },
-            alloc,
-        ),
-
+    var spawn_opts: std.process.SpawnOptions = switch (builtin.os.tag) {
+        .linux, .freebsd => .{ .argv = &.{ "xdg-open", url } },
+        .windows => .{ .argv = &.{ "rundll32", "url.dll,FileProtocolHandler", url } },
+        .macos => switch (kind) {
+            .text => .{ .argv = &.{ "open", "-t", url } },
+            .html, .unknown => .{ .argv = &.{ "open", url } },
+        },
         .ios => return error.Unimplemented,
         else => @compileError("unsupported OS"),
     };
-
     // Ignore anything from stdout. This must be set before spawning the
     // process.
-    exe.stdout_behavior = .Ignore;
+    spawn_opts.stdout = .ignore;
     // Pipe stderr so we can log the stderr from the command. This must be set
     // before spawning the process.
-    exe.stderr_behavior = .Pipe;
+    spawn_opts.stderr = .pipe;
 
-    // In the snap on Linux the launcher exports LD_LIBRARY_PATH pointing at
-    // the snap's bundled libraries. Leaking this into child process can can be
-    // problematic, so let's drop it from the env
-    var snap_env: std.process.EnvMap = if (comptime build_config.snap) blk: {
-        var env = try std.process.getEnvMap(alloc);
-        env.remove("LD_LIBRARY_PATH");
-        break :blk env;
-    } else undefined;
-    defer if (comptime build_config.snap) snap_env.deinit();
-    if (comptime build_config.snap) exe.env_map = &snap_env;
+    const exe = if (comptime build_config.snap) local_env: {
+        // In the snap on Linux the launcher exports LD_LIBRARY_PATH
+        // pointing at the snap's bundled libraries. Leaking this into
+        // child process can can be problematic, so let's drop it from the
+        // env.
+        //
+        // Note that `spawn` copies the passed in `Environ.Map` into a
+        // fresh `Environ` block, so this is safe to release immediately
+        // after spawn.
+        var environ_map = try global.environMap();
+        defer environ_map.deinit();
+        _ = environ_map.orderedRemove("LD_LIBRARY_PATH");
+        spawn_opts.environ_map = &environ_map;
+        break :local_env try std.process.spawn(global.io(), spawn_opts);
+    } else
+        // Non-snap releases don't need to alter the env.
+        try std.process.spawn(global.io(), spawn_opts);
 
-    // Spawn the process on our same thread so we can detect failure
-    // quickly.
-    try exe.spawn();
-
-    // Create a thread that handles collecting output and reaping the process.
-    // This is done in a separate thread because SOME open implementations block
-    // and some do not. It's easier to just spawn a thread to handle this so
-    // that we never block.
-    const thread = try std.Thread.spawn(.{}, openThread, .{exe});
+    const thread = try std.Thread.spawn(.{}, openThread, .{ global.io(), exe });
     thread.detach();
 }
 
-fn openThread(exe_: std.process.Child) void {
+fn openThread(io: std.Io, exe_: std.process.Child) void {
     // Copy the exe so it is non-const. This is necessary because wait()
     // requires a mutable reference and we can't have one as a thread
     // param.
     var exe = exe_;
     if (exe.stderr) |stderr| {
         var buffer: [256]u8 = undefined;
-        var stream = stderr.readerStreaming(&buffer);
+        var stream = stderr.readerStreaming(io, &buffer);
         const reader = &stream.interface;
         while (true) {
             const line = reader.takeDelimiterExclusive('\n') catch |outer| switch (outer) {
@@ -93,5 +79,5 @@ fn openThread(exe_: std.process.Child) void {
             log.warn("open stderr={s}", .{line});
         }
     }
-    _ = exe.wait() catch {};
+    _ = exe.wait(io) catch {};
 }
diff --git a/src/os/passwd.zig b/src/os/passwd.zig
index e9bbff066..7c16e54ec 100644
--- a/src/os/passwd.zig
+++ b/src/os/passwd.zig
@@ -5,6 +5,7 @@ const build_config = @import("../build_config.zig");
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
 const posix = std.posix;
+const compat_fd = @import("../lib/compat/fd.zig");
 
 const log = std.log.scoped(.passwd);
 
@@ -89,11 +90,11 @@ pub fn get(alloc: Allocator) !Entry {
         // Once started, we can close the child side. We do this after
         // wait right now but that is fine too. This lets us read the
         // parent and detect EOF.
-        _ = posix.close(pty.slave);
+        _ = compat_fd.close(pty.slave);
 
         // Read all of our output
         const output = output: {
-            var output: std.ArrayListUnmanaged(u8) = .{};
+            var output: std.ArrayListUnmanaged(u8) = .empty;
             while (true) {
                 const n = posix.read(pty.master, &buf) catch |err| {
                     switch (err) {
@@ -116,7 +117,7 @@ pub fn get(alloc: Allocator) !Entry {
         };
 
         // Shell and home are the last two entries
-        var it = std.mem.splitBackwardsScalar(u8, std.mem.trimRight(u8, output, " \r\n"), ':');
+        var it = std.mem.splitBackwardsScalar(u8, std.mem.trimEnd(u8, output, " \r\n"), ':');
         result.shell = if (it.next()) |v| try alloc.dupeZ(u8, v) else null;
         result.home = if (it.next()) |v| try alloc.dupeZ(u8, v) else null;
         return result;
diff --git a/src/os/path.zig b/src/os/path.zig
index 730ae692d..ba1a63f7f 100644
--- a/src/os/path.zig
+++ b/src/os/path.zig
@@ -6,22 +6,19 @@ const testing = std.testing;
 /// Search for "cmd" in the PATH and return the absolute path. This will
 /// always allocate if there is a non-null result. The caller must free the
 /// resulting value.
-pub fn expand(alloc: Allocator, cmd: []const u8) !?[]u8 {
+pub fn expand(
+    io: std.Io,
+    alloc: Allocator,
+    environ_map: *const std.process.Environ.Map,
+    cmd: []const u8,
+) !?[]u8 {
     // If the command already contains a slash, then we return it as-is
     // because it is assumed to be absolute or relative.
     if (std.mem.indexOfScalar(u8, cmd, '/') != null) {
         return try alloc.dupe(u8, cmd);
     }
 
-    const PATH = switch (builtin.os.tag) {
-        .windows => blk: {
-            const win_path = std.process.getenvW(std.unicode.utf8ToUtf16LeStringLiteral("PATH")) orelse return null;
-            const path = try std.unicode.utf16LeToUtf8Alloc(alloc, win_path);
-            break :blk path;
-        },
-        else => std.posix.getenvZ("PATH") orelse return null,
-    };
-    defer if (builtin.os.tag == .windows) alloc.free(PATH);
+    const PATH = environ_map.get("PATH") orelse return null;
 
     var path_buf: [std.fs.max_path_bytes]u8 = undefined;
     var it = std.mem.tokenizeScalar(u8, PATH, std.fs.path.delimiter);
@@ -39,7 +36,8 @@ pub fn expand(alloc: Allocator, cmd: []const u8) !?[]u8 {
         const full_path = path_buf[0..path_len :0];
 
         // Stat it
-        const f = std.fs.cwd().openFile(
+        const f = std.Io.Dir.cwd().openFile(
+            io,
             full_path,
             .{},
         ) catch |err| switch (err) {
@@ -52,9 +50,9 @@ pub fn expand(alloc: Allocator, cmd: []const u8) !?[]u8 {
             },
             else => return err,
         };
-        defer f.close();
-        const stat = try f.stat();
-        if (stat.kind != .directory and isExecutable(stat.mode)) {
+        defer f.close(io);
+        const stat = try f.stat(io);
+        if (stat.kind != .directory and isExecutable(stat.permissions)) {
             return try alloc.dupe(u8, full_path);
         }
     }
@@ -64,26 +62,39 @@ pub fn expand(alloc: Allocator, cmd: []const u8) !?[]u8 {
     return null;
 }
 
-fn isExecutable(mode: std.fs.File.Mode) bool {
-    if (builtin.os.tag == .windows) return true;
-    return mode & 0o0111 != 0;
+fn isExecutable(perms: std.Io.File.Permissions) bool {
+    return switch (builtin.os.tag) {
+        .windows => true,
+        else => posix: {
+            break :posix switch (std.posix.mode_t) {
+                u0 => true,
+                else => perms.toMode() & 0o0111 != 0,
+            };
+        },
+    };
 }
 
 // `uname -n` is the *nix equivalent of `hostname.exe` on Windows
 test "expand: hostname" {
+    var environ_map = try testing.environ.createMap(testing.allocator);
+    defer environ_map.deinit();
     const executable = if (builtin.os.tag == .windows) "hostname.exe" else "uname";
-    const path = (try expand(testing.allocator, executable)).?;
+    const path = (try expand(testing.io, testing.allocator, &environ_map, executable)).?;
     defer testing.allocator.free(path);
     try testing.expect(path.len > executable.len);
 }
 
 test "expand: does not exist" {
-    const path = try expand(testing.allocator, "thisreallyprobablydoesntexist123");
+    var environ_map = try testing.environ.createMap(testing.allocator);
+    defer environ_map.deinit();
+    const path = try expand(testing.io, testing.allocator, &environ_map, "thisreallyprobablydoesntexist123");
     try testing.expect(path == null);
 }
 
 test "expand: slash" {
-    const path = (try expand(testing.allocator, "foo/env")).?;
+    var environ_map = try testing.environ.createMap(testing.allocator);
+    defer environ_map.deinit();
+    const path = (try expand(testing.io, testing.allocator, &environ_map, "foo/env")).?;
     defer testing.allocator.free(path);
     try testing.expect(path.len == 7);
 }
diff --git a/src/os/pipe.zig b/src/os/pipe.zig
index 2cb7bd4a3..0310fb3ed 100644
--- a/src/os/pipe.zig
+++ b/src/os/pipe.zig
@@ -2,17 +2,18 @@ const std = @import("std");
 const builtin = @import("builtin");
 const windows = @import("windows.zig");
 const posix = std.posix;
+const compat_fd = @import("../lib/compat/fd.zig");
 
 /// pipe() that works on Windows and POSIX. For POSIX systems, this sets
 /// CLOEXEC on the file descriptors.
 pub fn pipe() ![2]posix.fd_t {
     switch (builtin.os.tag) {
-        else => return try posix.pipe2(.{ .CLOEXEC = true }),
+        else => return compat_fd.pipe2(.{ .CLOEXEC = true }),
         .windows => {
             var read: windows.HANDLE = undefined;
             var write: windows.HANDLE = undefined;
-            if (windows.exp.kernel32.CreatePipe(&read, &write, null, 0) == 0) {
-                return windows.unexpectedError(windows.kernel32.GetLastError());
+            if (windows.exp.kernel32.CreatePipe(&read, &write, null, 0) == windows.FALSE) {
+                return windows.unexpectedError(windows.GetLastError());
             }
 
             return .{ read, write };
diff --git a/src/os/resourcesdir.zig b/src/os/resourcesdir.zig
index 278de44fc..ef8b5a287 100644
--- a/src/os/resourcesdir.zig
+++ b/src/os/resourcesdir.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
+const global = @import("../global.zig");
 
 pub const ResourcesDir = struct {
     /// Avoid accessing these directly, use the app() and host() methods instead.
@@ -16,7 +17,7 @@ pub const ResourcesDir = struct {
 
     /// Get the directory to the bundled resources directory accessible
     /// by the application.
-    pub fn app(self: *ResourcesDir) ?[]const u8 {
+    pub fn app(self: *const ResourcesDir) ?[]const u8 {
         return self.app_path;
     }
 
@@ -26,7 +27,7 @@ pub const ResourcesDir = struct {
     /// itself.
     ///
     /// In non-sandboxed environment, this should be the same as app().
-    pub fn host(self: *ResourcesDir) ?[]const u8 {
+    pub fn host(self: *const ResourcesDir) ?[]const u8 {
         return self.host_path orelse self.app_path;
     }
 };
@@ -47,13 +48,13 @@ pub fn resourcesDir(alloc: Allocator) !ResourcesDir {
     //
     // Note: we ALWAYS want to allocate here because the result is always
     // freed, do not try to use internal_os.getenv or posix getenv.
-    if (comptime builtin.mode != .Debug) {
-        if (std.process.getEnvVarOwned(alloc, "GHOSTTY_RESOURCES_DIR")) |dir| {
-            if (dir.len > 0) return .{ .app_path = dir };
-        } else |err| switch (err) {
-            error.EnvironmentVariableNotFound => {},
+    if (comptime builtin.mode != .Debug) env: {
+        const dir = global.environ().getAlloc(alloc, "GHOSTTY_RESOURCES_DIR") catch |err| switch (err) {
+            error.EnvironmentVariableMissing => break :env,
             else => return err,
-        }
+        };
+
+        if (dir.len > 0) return .{ .app_path = dir };
     }
 
     // This is the sentinel value we look for in the path to know
@@ -67,7 +68,10 @@ pub fn resourcesDir(alloc: Allocator) !ResourcesDir {
 
     // Get the path to our running binary
     var exe_buf: [std.fs.max_path_bytes]u8 = undefined;
-    var exe: []const u8 = std.fs.selfExePath(&exe_buf) catch return .{};
+    var exe: []const u8 = exe_buf[0 .. std.process.executablePath(
+        global.io(),
+        &exe_buf,
+    ) catch return .{}];
 
     // We have an exe path! Climb the tree looking for the terminfo
     // bundle as we expect it.
@@ -78,7 +82,12 @@ pub fn resourcesDir(alloc: Allocator) !ResourcesDir {
         // On MacOS, we look for the app bundle path.
         if (comptime builtin.target.os.tag.isDarwin()) {
             inline for (sentinels) |sentinel| {
-                if (try maybeDir(&dir_buf, dir, "Contents/Resources", sentinel)) |v| {
+                if (try maybeDir(
+                    &dir_buf,
+                    dir,
+                    "Contents/Resources",
+                    sentinel,
+                )) |v| {
                     return .{ .app_path = try std.fs.path.join(alloc, &.{ v, "ghostty" }) };
                 }
             }
@@ -102,10 +111,10 @@ pub fn resourcesDir(alloc: Allocator) !ResourcesDir {
     // If terminfo detection failed in debug builds (somehow),
     // fallback and use the provided resources dir.
     if (comptime builtin.mode == .Debug) {
-        if (std.process.getEnvVarOwned(alloc, "GHOSTTY_RESOURCES_DIR")) |dir| {
+        if (global.environ().getAlloc(alloc, "GHOSTTY_RESOURCES_DIR")) |dir| {
             if (dir.len > 0) return .{ .app_path = dir };
         } else |err| switch (err) {
-            error.EnvironmentVariableNotFound => {},
+            error.InvalidWtf8, error.EnvironmentVariableMissing => {},
             else => return err,
         }
     }
@@ -127,7 +136,7 @@ pub fn maybeDir(
 ) !?[]const u8 {
     const path = try std.fmt.bufPrint(buf, "{s}/{s}/{s}", .{ base, sub, suffix });
 
-    if (std.fs.accessAbsolute(path, .{})) {
+    if (std.Io.Dir.accessAbsolute(global.io(), path, .{})) {
         const len = path.len - suffix.len - 1;
         return buf[0..len];
     } else |_| {
diff --git a/src/os/systemd.zig b/src/os/systemd.zig
index 1a9a10ee7..5815648a1 100644
--- a/src/os/systemd.zig
+++ b/src/os/systemd.zig
@@ -1,5 +1,6 @@
 const std = @import("std");
 const builtin = @import("builtin");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.systemd);
 
@@ -16,8 +17,8 @@ pub fn launchedBySystemd() bool {
             // `JOURNAL_STREAM` (v231+) environment variables. If these
             // environment variables are not present we were not launched by
             // systemd.
-            if (std.posix.getenv("INVOCATION_ID") == null) break :linux false;
-            if (std.posix.getenv("JOURNAL_STREAM") == null) break :linux false;
+            if (global.environ().getPosix("INVOCATION_ID") == null) break :linux false;
+            if (global.environ().getPosix("JOURNAL_STREAM") == null) break :linux false;
 
             // If `INVOCATION_ID` and `JOURNAL_STREAM` are present, check to make sure
             // that our parent process is actually `systemd`, not some other terminal
@@ -33,7 +34,7 @@ pub fn launchedBySystemd() bool {
                 log.err("unable to format comm path for pid {d}", .{ppid});
                 break :linux false;
             };
-            const comm_file = std.fs.openFileAbsolute(comm_path, .{ .mode = .read_only }) catch {
+            const comm_file = std.Io.Dir.openFileAbsolute(global.io(), comm_path, .{ .mode = .read_only }) catch {
                 log.err("unable to open '{s}' for reading", .{comm_path});
                 break :linux false;
             };
@@ -91,7 +92,7 @@ pub const notify = struct {
         if (comptime builtin.os.tag != .linux) return;
 
         // Get the socket address that should receive notifications.
-        const socket_path = std.posix.getenv("NOTIFY_SOCKET") orelse return;
+        const socket_path = global.environ().getPosix("NOTIFY_SOCKET") orelse return;
 
         // If the socket address is an empty string return.
         if (socket_path.len == 0) return;
@@ -121,7 +122,7 @@ pub const notify = struct {
                 std.os.linux.SOCK.DGRAM | std.os.linux.SOCK.CLOEXEC,
                 0,
             );
-            switch (std.os.linux.E.init(rc)) {
+            switch (linuxErrnoFromSyscall(rc)) {
                 .SUCCESS => break :socket @intCast(rc),
                 else => |e| {
                     log.warn("creating socket failed: {s}", .{@tagName(e)});
@@ -138,7 +139,7 @@ pub const notify = struct {
                 &socket_address,
                 @offsetOf(std.os.linux.sockaddr.un, "path") + socket_address.path.len,
             );
-            switch (std.os.linux.E.init(rc)) {
+            switch (linuxErrnoFromSyscall(rc)) {
                 .SUCCESS => break :connect,
                 else => |e| {
                     log.warn("unable to connect to notify socket: {s}", .{@tagName(e)});
@@ -149,7 +150,7 @@ pub const notify = struct {
 
         write: {
             const rc = std.os.linux.write(socket, message.ptr, message.len);
-            switch (std.os.linux.E.init(rc)) {
+            switch (linuxErrnoFromSyscall(rc)) {
                 .SUCCESS => {
                     const written = rc;
                     if (written < message.len) {
@@ -180,12 +181,7 @@ pub const notify = struct {
     pub fn reloading() void {
         if (comptime builtin.os.tag != .linux) return;
 
-        const ts = std.posix.clock_gettime(.MONOTONIC) catch |err| {
-            log.err("unable to get MONOTONIC clock: {}", .{err});
-            return;
-        };
-
-        const now = ts.sec * std.time.us_per_s + @divFloor(ts.nsec, std.time.ns_per_us);
+        const now = std.Io.Timestamp.now(global.io(), .awake).toMicroseconds();
 
         var buffer: [64]u8 = undefined;
         const message = std.fmt.bufPrint(&buffer, "RELOADING=1\nMONOTONIC_USEC={d}", .{now}) catch |err| {
@@ -196,3 +192,9 @@ pub const notify = struct {
         send(message);
     }
 };
+
+fn linuxErrnoFromSyscall(r: usize) std.os.linux.E {
+    const signed_r: isize = @bitCast(r);
+    const int = if (signed_r > -4096 and signed_r < 0) -signed_r else 0;
+    return @enumFromInt(int);
+}
diff --git a/src/os/windows.zig b/src/os/windows.zig
index 6e452fb73..feef8ce92 100644
--- a/src/os/windows.zig
+++ b/src/os/windows.zig
@@ -1,139 +1,273 @@
 const std = @import("std");
 const windows = std.os.windows;
 
-// Export any constants or functions we need from the Windows API so
-// we can just import one file.
-pub const kernel32 = windows.kernel32;
-pub const unexpectedError = windows.unexpectedError;
-pub const OpenFile = windows.OpenFile;
-pub const CloseHandle = windows.CloseHandle;
+// NOTE: The Windows part of the Zig stdlib is currently in the process of
+// having most of its features removed, with the ultimate goal of switching to
+// serve as a support for higher-level functionality offered in places like
+// `std.Io` only. As such this file serves as a "bridge" between type
+// information (mostly coming from stdlib) and manually-defined constants and
+// external functions.
+
+// Utility functions
 pub const GetCurrentProcessId = windows.GetCurrentProcessId;
-pub const SetHandleInformation = windows.SetHandleInformation;
+pub const GetLastError = windows.GetLastError;
+pub const unexpectedError = windows.unexpectedError;
+pub const unexpectedStatus = windows.unexpectedStatus;
+
+// Primitive types
+pub const BOOL = windows.BOOL;
+pub const COORD = windows.COORD;
 pub const DWORD = windows.DWORD;
-pub const FILE_ATTRIBUTE_NORMAL = windows.FILE_ATTRIBUTE_NORMAL;
-pub const FILE_FLAG_OVERLAPPED = windows.FILE_FLAG_OVERLAPPED;
-pub const FILE_SHARE_READ = windows.FILE_SHARE_READ;
-pub const GENERIC_READ = windows.GENERIC_READ;
+pub const DWORD_PTR = windows.DWORD_PTR;
 pub const HANDLE = windows.HANDLE;
-pub const HANDLE_FLAG_INHERIT = windows.HANDLE_FLAG_INHERIT;
-pub const INFINITE = windows.INFINITE;
+pub const HINSTANCE = windows.HINSTANCE;
+pub const HPCON = windows.LPVOID;
+pub const HRESULT = c_long;
+pub const LARGE_INTEGER = windows.LARGE_INTEGER;
+pub const LPCWSTR = windows.LPCWSTR;
+pub const LPSTR = windows.LPSTR;
+pub const LPVOID = windows.LPVOID;
+pub const LPWSTR = windows.LPWSTR;
+pub const PVOID = windows.PVOID;
+pub const SIZE_T = windows.SIZE_T;
+pub const UINT = windows.UINT;
+pub const ULONG = windows.ULONG;
+pub const ULONG_PTR = windows.ULONG_PTR;
+pub const UNICODE_STRING = windows.UNICODE_STRING;
+
+// Structs and opaque types
+pub const LPPROC_THREAD_ATTRIBUTE_LIST = ?*anyopaque;
+pub const SECURITY_ATTRIBUTES = windows.SECURITY_ATTRIBUTES;
+pub const STARTF_USESTDHANDLES = windows.STARTF_USESTDHANDLES;
+pub const STARTUPINFOW = windows.STARTUPINFOW;
+
+pub const OVERLAPPED = extern struct {
+    Internal: ULONG_PTR,
+    InternalHigh: ULONG_PTR,
+    DUMMYUNIONNAME: extern union {
+        DUMMYSTRUCTNAME: extern struct {
+            Offset: DWORD,
+            OffsetHigh: DWORD,
+        },
+        Pointer: ?PVOID,
+    },
+    hEvent: ?HANDLE,
+};
+pub const PROCESS_INFORMATION = extern struct {
+    hProcess: HANDLE,
+    hThread: HANDLE,
+    dwProcessId: DWORD,
+    dwThreadId: DWORD,
+};
+pub const STARTUPINFOEX = extern struct {
+    StartupInfo: windows.STARTUPINFOW,
+    lpAttributeList: LPPROC_THREAD_ATTRIBUTE_LIST,
+};
+
+// Well-known constant values
+pub const INFINITE = 4294967295;
 pub const INVALID_HANDLE_VALUE = windows.INVALID_HANDLE_VALUE;
 pub const MAX_PATH = windows.MAX_PATH;
-pub const OPEN_EXISTING = windows.OPEN_EXISTING;
-pub const PIPE_ACCESS_OUTBOUND = windows.PIPE_ACCESS_OUTBOUND;
-pub const PIPE_TYPE_BYTE = windows.PIPE_TYPE_BYTE;
-pub const PROCESS_INFORMATION = windows.PROCESS_INFORMATION;
-pub const S_OK = windows.S_OK;
-pub const SECURITY_ATTRIBUTES = windows.SECURITY_ATTRIBUTES;
-pub const STARTUPINFOW = windows.STARTUPINFOW;
-pub const STARTF_USESTDHANDLES = windows.STARTF_USESTDHANDLES;
-pub const SYNCHRONIZE = windows.SYNCHRONIZE;
-pub const WAIT_FAILED = windows.WAIT_FAILED;
-pub const FALSE = windows.FALSE;
-pub const TRUE = windows.TRUE;
+pub const FALSE: windows.BOOL = .fromBool(false);
+pub const TRUE: windows.BOOL = .fromBool(true);
 
+// Bit-field and enum constant values
+pub const CREATE_UNICODE_ENVIRONMENT = 0x00000400;
+pub const EXTENDED_STARTUPINFO_PRESENT = 0x00080000;
+pub const FILE_ATTRIBUTE_NORMAL = 0x80;
+pub const FILE_FLAG_FIRST_PIPE_INSTANCE = 0x00080000;
+pub const FILE_FLAG_OVERLAPPED = 0x40000000;
+pub const FILE_NON_DIRECTORY_FILE = 0x00000040;
+pub const FILE_SHARE_READ = 0x00000001;
+pub const GENERIC_READ = 0x80000000;
+pub const HANDLE_FLAG_INHERIT = 0x00000001;
+pub const MEM_COMMIT = 0x1000;
+pub const MEM_RELEASE = 0x8000;
+pub const MEM_RESERVE = 0x2000;
+pub const OPEN_EXISTING = 3; // Known as FILE_OPEN in Windows docs
+pub const PAGE_READWRITE = 0x04;
+pub const PIPE_ACCESS_OUTBOUND = 0x00000002;
+pub const PIPE_TYPE_BYTE = 0x00000000;
+pub const PROC_THREAD_ATTRIBUTE_ADDITIVE = 0x00040000;
+pub const PROC_THREAD_ATTRIBUTE_INPUT = 0x00020000;
+pub const PROC_THREAD_ATTRIBUTE_NUMBER = 0x0000FFFF;
+pub const PROC_THREAD_ATTRIBUTE_THREAD = 0x00010000;
+pub const S_OK = 0;
+pub const WAIT_FAILED = 0xFFFFFFFF;
+
+pub const PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE = ProcThreadAttributeValue(
+    .ProcThreadAttributePseudoConsole,
+    false,
+    true,
+    false,
+);
+
+// Types needed for ntdll calls
+pub const ACCESS_MASK = windows.ACCESS_MASK;
+pub const IO_STATUS_BLOCK = windows.IO_STATUS_BLOCK;
+pub const NTSTATUS = windows.NTSTATUS;
+pub const OBJECT_ATTRIBUTES = windows.OBJECT.ATTRIBUTES;
+
+// Exported functions by library
 pub const exp = struct {
-    pub const HPCON = windows.LPVOID;
-
-    pub const CREATE_UNICODE_ENVIRONMENT = 0x00000400;
-    pub const EXTENDED_STARTUPINFO_PRESENT = 0x00080000;
-    pub const LPPROC_THREAD_ATTRIBUTE_LIST = ?*anyopaque;
-    pub const FILE_FLAG_FIRST_PIPE_INSTANCE = 0x00080000;
-
-    pub const STATUS_PENDING = 0x00000103;
-    pub const STILL_ACTIVE = STATUS_PENDING;
-
-    pub const STARTUPINFOEX = extern struct {
-        StartupInfo: windows.STARTUPINFOW,
-        lpAttributeList: LPPROC_THREAD_ATTRIBUTE_LIST,
-    };
-
     pub const kernel32 = struct {
         pub extern "kernel32" fn CreatePipe(
-            hReadPipe: *windows.HANDLE,
-            hWritePipe: *windows.HANDLE,
-            lpPipeAttributes: ?*const windows.SECURITY_ATTRIBUTES,
-            nSize: windows.DWORD,
-        ) callconv(.winapi) windows.BOOL;
+            hReadPipe: *HANDLE,
+            hWritePipe: *HANDLE,
+            lpPipeAttributes: ?*const SECURITY_ATTRIBUTES,
+            nSize: DWORD,
+        ) callconv(.winapi) BOOL;
         pub extern "kernel32" fn CreatePseudoConsole(
-            size: windows.COORD,
-            hInput: windows.HANDLE,
-            hOutput: windows.HANDLE,
-            dwFlags: windows.DWORD,
+            size: COORD,
+            hInput: HANDLE,
+            hOutput: HANDLE,
+            dwFlags: DWORD,
             phPC: *HPCON,
-        ) callconv(.winapi) windows.HRESULT;
-        pub extern "kernel32" fn ResizePseudoConsole(hPC: HPCON, size: windows.COORD) callconv(.winapi) windows.HRESULT;
+        ) callconv(.winapi) HRESULT;
+        pub extern "kernel32" fn ResizePseudoConsole(
+            hPC: HPCON,
+            size: COORD,
+        ) callconv(.winapi) HRESULT;
         pub extern "kernel32" fn ClosePseudoConsole(hPC: HPCON) callconv(.winapi) void;
         pub extern "kernel32" fn InitializeProcThreadAttributeList(
             lpAttributeList: LPPROC_THREAD_ATTRIBUTE_LIST,
-            dwAttributeCount: windows.DWORD,
-            dwFlags: windows.DWORD,
-            lpSize: *windows.SIZE_T,
-        ) callconv(.winapi) windows.BOOL;
+            dwAttributeCount: DWORD,
+            dwFlags: DWORD,
+            lpSize: *SIZE_T,
+        ) callconv(.winapi) BOOL;
         pub extern "kernel32" fn UpdateProcThreadAttribute(
             lpAttributeList: LPPROC_THREAD_ATTRIBUTE_LIST,
-            dwFlags: windows.DWORD,
-            Attribute: windows.DWORD_PTR,
-            lpValue: windows.PVOID,
-            cbSize: windows.SIZE_T,
-            lpPreviousValue: ?windows.PVOID,
-            lpReturnSize: ?*windows.SIZE_T,
-        ) callconv(.winapi) windows.BOOL;
+            dwFlags: DWORD,
+            Attribute: DWORD_PTR,
+            lpValue: PVOID,
+            cbSize: SIZE_T,
+            lpPreviousValue: ?PVOID,
+            lpReturnSize: ?*SIZE_T,
+        ) callconv(.winapi) BOOL;
         pub extern "kernel32" fn PeekNamedPipe(
-            hNamedPipe: windows.HANDLE,
-            lpBuffer: ?windows.LPVOID,
-            nBufferSize: windows.DWORD,
-            lpBytesRead: ?*windows.DWORD,
-            lpTotalBytesAvail: ?*windows.DWORD,
-            lpBytesLeftThisMessage: ?*windows.DWORD,
-        ) callconv(.winapi) windows.BOOL;
+            hNamedPipe: HANDLE,
+            lpBuffer: ?LPVOID,
+            nBufferSize: DWORD,
+            lpBytesRead: ?*DWORD,
+            lpTotalBytesAvail: ?*DWORD,
+            lpBytesLeftThisMessage: ?*DWORD,
+        ) callconv(.winapi) BOOL;
         // Duplicated here because lpCommandLine is not marked optional in zig std
         pub extern "kernel32" fn CreateProcessW(
-            lpApplicationName: ?windows.LPWSTR,
-            lpCommandLine: ?windows.LPWSTR,
-            lpProcessAttributes: ?*windows.SECURITY_ATTRIBUTES,
-            lpThreadAttributes: ?*windows.SECURITY_ATTRIBUTES,
-            bInheritHandles: windows.BOOL,
-            dwCreationFlags: windows.DWORD,
+            lpApplicationName: ?LPWSTR,
+            lpCommandLine: ?LPWSTR,
+            lpProcessAttributes: ?*SECURITY_ATTRIBUTES,
+            lpThreadAttributes: ?*SECURITY_ATTRIBUTES,
+            bInheritHandles: BOOL,
+            dwCreationFlags: DWORD,
             lpEnvironment: ?*anyopaque,
-            lpCurrentDirectory: ?windows.LPWSTR,
-            lpStartupInfo: *windows.STARTUPINFOW,
-            lpProcessInformation: *windows.PROCESS_INFORMATION,
-        ) callconv(.winapi) windows.BOOL;
+            lpCurrentDirectory: ?LPWSTR,
+            lpStartupInfo: *STARTUPINFOW,
+            lpProcessInformation: *PROCESS_INFORMATION,
+        ) callconv(.winapi) BOOL;
         /// https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getcomputernamea
         pub extern "kernel32" fn GetComputerNameA(
-            lpBuffer: windows.LPSTR,
-            nSize: *windows.DWORD,
-        ) callconv(.winapi) windows.BOOL;
+            lpBuffer: LPSTR,
+            nSize: *DWORD,
+        ) callconv(.winapi) BOOL;
         /// https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-gettemppathw
         pub extern "kernel32" fn GetTempPathW(
-            nBufferLength: windows.DWORD,
-            lpBuffer: windows.LPWSTR,
-        ) callconv(.winapi) windows.DWORD;
+            nBufferLength: DWORD,
+            lpBuffer: LPWSTR,
+        ) callconv(.winapi) DWORD;
+        pub extern "kernel32" fn SetHandleInformation(
+            hObject: HANDLE,
+            dwMask: DWORD,
+            dwFlags: DWORD,
+        ) callconv(.winapi) BOOL;
+        pub extern "kernel32" fn CreateFileW(
+            lpFileName: LPCWSTR,
+            dwDesiredAccess: DWORD,
+            dwShareMode: DWORD,
+            lpSecurityAttributes: ?*SECURITY_ATTRIBUTES,
+            dwCreationDisposition: DWORD,
+            dwFlagsAndAttributes: DWORD,
+            hTemplateFile: ?HANDLE,
+        ) callconv(.winapi) HANDLE;
+        pub extern "kernel32" fn CreateNamedPipeW(
+            lpName: LPCWSTR,
+            dwOpenMode: DWORD,
+            dwPipeMode: DWORD,
+            nMaxInstances: DWORD,
+            nOutBufferSize: DWORD,
+            nInBufferSize: DWORD,
+            nDefaultTimeOut: DWORD,
+            lpSecurityAttributes: ?*const SECURITY_ATTRIBUTES,
+        ) callconv(.winapi) HANDLE;
+        pub extern "kernel32" fn CloseHandle(
+            hObject: HANDLE,
+        ) callconv(.winapi) BOOL;
+        pub extern "kernel32" fn VirtualAlloc(
+            lpAddress: ?LPVOID,
+            dwSize: SIZE_T,
+            flAllocationType: DWORD,
+            flProtect: DWORD,
+        ) callconv(.winapi) ?LPVOID;
+        pub extern "kernel32" fn VirtualFree(
+            lpAddress: ?LPVOID,
+            dwSize: SIZE_T,
+            dwFreeType: DWORD,
+        ) callconv(.winapi) BOOL;
+        pub extern "kernel32" fn WaitForSingleObject(
+            hHandle: HANDLE,
+            dwMilliseconds: DWORD,
+        ) callconv(.winapi) DWORD;
+        pub extern "kernel32" fn GetExitCodeProcess(
+            hProcess: HANDLE,
+            lpExitCode: *DWORD,
+        ) callconv(.winapi) BOOL;
+        pub extern "kernel32" fn TerminateProcess(
+            hProcess: HANDLE,
+            uExitCode: UINT,
+        ) callconv(.winapi) BOOL;
+        pub extern "kernel32" fn CancelIoEx(
+            hFile: HANDLE,
+            lpOverlapped: ?*OVERLAPPED,
+        ) callconv(.winapi) BOOL;
+        pub extern "kernel32" fn ReadFile(
+            hFile: HANDLE,
+            lpBuffer: LPVOID,
+            nNumberOfBytesToRead: DWORD,
+            lpNumberOfBytesRead: ?*DWORD,
+            lpOverlapped: ?*OVERLAPPED,
+        ) callconv(.winapi) BOOL;
     };
-
-    pub const PROC_THREAD_ATTRIBUTE_NUMBER = 0x0000FFFF;
-    pub const PROC_THREAD_ATTRIBUTE_THREAD = 0x00010000;
-    pub const PROC_THREAD_ATTRIBUTE_INPUT = 0x00020000;
-    pub const PROC_THREAD_ATTRIBUTE_ADDITIVE = 0x00040000;
-
-    pub const ProcThreadAttributeNumber = enum(windows.DWORD) {
-        ProcThreadAttributePseudoConsole = 22,
-        _,
+    pub const ntdll = struct {
+        pub extern "ntdll" fn NtCreateFile(
+            FileHandle: *HANDLE,
+            DesiredAccess: ACCESS_MASK,
+            ObjectAttributes: *OBJECT_ATTRIBUTES,
+            IoStatusBlock: *IO_STATUS_BLOCK,
+            AllocationSize: ?*LARGE_INTEGER,
+            FileAttributes: ULONG,
+            ShareAccess: ULONG,
+            CreateDisposition: ULONG,
+            CreateOptions: ULONG,
+            EaBuffer: ?*anyopaque,
+            EaLength: ULONG,
+        ) callconv(.winapi) NTSTATUS;
     };
-
-    /// Corresponds to the ProcThreadAttributeValue define in WinBase.h
-    pub fn ProcThreadAttributeValue(
-        comptime attribute: ProcThreadAttributeNumber,
-        comptime thread: bool,
-        comptime input: bool,
-        comptime additive: bool,
-    ) windows.DWORD {
-        return (@intFromEnum(attribute) & PROC_THREAD_ATTRIBUTE_NUMBER) |
-            (if (thread) PROC_THREAD_ATTRIBUTE_THREAD else 0) |
-            (if (input) PROC_THREAD_ATTRIBUTE_INPUT else 0) |
-            (if (additive) PROC_THREAD_ATTRIBUTE_ADDITIVE else 0);
-    }
-
-    pub const PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE = ProcThreadAttributeValue(.ProcThreadAttributePseudoConsole, false, true, false);
 };
+
+pub const ProcThreadAttributeNumber = enum(DWORD) {
+    ProcThreadAttributePseudoConsole = 22,
+    _,
+};
+
+/// Corresponds to the ProcThreadAttributeValue define in WinBase.h
+pub fn ProcThreadAttributeValue(
+    comptime attribute: ProcThreadAttributeNumber,
+    comptime thread: bool,
+    comptime input: bool,
+    comptime additive: bool,
+) DWORD {
+    return (@intFromEnum(attribute) & PROC_THREAD_ATTRIBUTE_NUMBER) |
+        (if (thread) PROC_THREAD_ATTRIBUTE_THREAD else 0) |
+        (if (input) PROC_THREAD_ATTRIBUTE_INPUT else 0) |
+        (if (additive) PROC_THREAD_ATTRIBUTE_ADDITIVE else 0);
+}
diff --git a/src/os/xdg.zig b/src/os/xdg.zig
index f2a495af4..7659bbd14 100644
--- a/src/os/xdg.zig
+++ b/src/os/xdg.zig
@@ -6,7 +6,7 @@ const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
 const posix = std.posix;
 const homedir = @import("homedir.zig");
-const env_os = @import("env.zig");
+const global = @import("../global.zig");
 
 pub const Options = struct {
     /// Subdirectories to join to the base. This avoids extra allocations
@@ -20,8 +20,8 @@ pub const Options = struct {
 };
 
 /// Get the XDG user config directory. The returned value is allocated.
-pub fn config(alloc: Allocator, opts: Options) ![]u8 {
-    return try dir(alloc, opts, .{
+pub fn config(alloc: Allocator, environ_map: *const std.process.Environ.Map, opts: Options) ![]u8 {
+    return try dir(alloc, environ_map, opts, .{
         .env = "XDG_CONFIG_HOME",
         .windows_env = "LOCALAPPDATA",
         .default_subdir = ".config",
@@ -29,8 +29,8 @@ pub fn config(alloc: Allocator, opts: Options) ![]u8 {
 }
 
 /// Get the XDG cache directory. The returned value is allocated.
-pub fn cache(alloc: Allocator, opts: Options) ![]u8 {
-    return try dir(alloc, opts, .{
+pub fn cache(alloc: Allocator, environ_map: *const std.process.Environ.Map, opts: Options) ![]u8 {
+    return try dir(alloc, environ_map, opts, .{
         .env = "XDG_CACHE_HOME",
         .windows_env = "LOCALAPPDATA",
         .default_subdir = ".cache",
@@ -38,8 +38,8 @@ pub fn cache(alloc: Allocator, opts: Options) ![]u8 {
 }
 
 /// Get the XDG state directory. The returned value is allocated.
-pub fn state(alloc: Allocator, opts: Options) ![]u8 {
-    return try dir(alloc, opts, .{
+pub fn state(alloc: Allocator, environ_map: *const std.process.Environ.Map, opts: Options) ![]u8 {
+    return try dir(alloc, environ_map, opts, .{
         .env = "XDG_STATE_HOME",
         .windows_env = "LOCALAPPDATA",
         .default_subdir = ".local/state",
@@ -55,6 +55,7 @@ const InternalOptions = struct {
 /// Unified helper to get XDG directories that follow a common pattern.
 fn dir(
     alloc: Allocator,
+    environ_map: *const std.process.Environ.Map,
     opts: Options,
     internal_opts: InternalOptions,
 ) ![]u8 {
@@ -67,30 +68,28 @@ fn dir(
         });
     }
 
-    // First check the env var. On Windows we have to allocate so this tracks
-    // both whether we have the env var and whether we own it.
-    // on Windows we treat `LOCALAPPDATA` as a fallback for `XDG_CONFIG_HOME`
-    const env_ = try env_os.getenvNotEmpty(alloc, internal_opts.env) orelse switch (builtin.os.tag) {
-        else => null,
-        .windows => try env_os.getenvNotEmpty(alloc, internal_opts.windows_env),
+    // First check the env var. On Windows we treat `LOCALAPPDATA` as a
+    // fallback for `XDG_CONFIG_HOME`
+    const env = switch (builtin.os.tag) {
+        .windows => environ_map.get(internal_opts.env) orelse environ_map.get(internal_opts.windows_env) orelse "",
+        else => environ_map.get(internal_opts.env) orelse "",
     };
-    defer if (env_) |env| env.deinit(alloc);
 
-    if (env_) |env| {
+    if (env.len > 0) {
         // If we have a subdir, then we use the env as-is to avoid a copy.
         if (opts.subdir) |subdir| {
             return try std.fs.path.join(alloc, &[_][]const u8{
-                env.value,
+                env,
                 subdir,
             });
         }
 
-        return try alloc.dupe(u8, env.value);
+        return try alloc.dupe(u8, env);
     }
 
     // Get our home dir
     var buf: [1024]u8 = undefined;
-    if (try homedir.home(&buf)) |home| {
+    if (try homedir.home(environ_map, &buf)) |home| {
         return try std.fs.path.join(alloc, &[_][]const u8{
             home,
             internal_opts.default_subdir,
@@ -121,9 +120,11 @@ pub fn parseTerminalExec(argv: []const [*:0]const u8) ?[]const [*:0]const u8 {
 test {
     const testing = std.testing;
     const alloc = testing.allocator;
+    var environ_map = try testing.environ.createMap(alloc);
+    defer environ_map.deinit();
 
     {
-        const value = try config(alloc, .{});
+        const value = try config(alloc, &environ_map, .{});
         defer alloc.free(value);
         try testing.expect(value.len > 0);
     }
@@ -133,12 +134,14 @@ test "cache directory paths" {
     const testing = std.testing;
     const alloc = testing.allocator;
     const mock_home = if (builtin.os.tag == .windows) "C:\\Users\\test" else "/Users/test";
+    var environ_map = try testing.environ.createMap(alloc);
+    defer environ_map.deinit();
 
     // Test when XDG_CACHE_HOME is not set
     {
         // Test base path
         {
-            const cache_path = try cache(alloc, .{ .home = mock_home });
+            const cache_path = try cache(alloc, &environ_map, .{ .home = mock_home });
             defer alloc.free(cache_path);
             const expected = try std.fs.path.join(alloc, &.{ mock_home, ".cache" });
             defer alloc.free(expected);
@@ -147,7 +150,7 @@ test "cache directory paths" {
 
         // Test with subdir
         {
-            const cache_path = try cache(alloc, .{
+            const cache_path = try cache(alloc, &environ_map, .{
                 .home = mock_home,
                 .subdir = "ghostty",
             });
@@ -164,24 +167,9 @@ test "fallback when xdg env empty" {
 
     const alloc = std.testing.allocator;
 
-    const saved_home = home: {
-        const home = std.posix.getenv("HOME") orelse break :home null;
-        break :home try alloc.dupeZ(u8, home);
-    };
-    defer env: {
-        const home = saved_home orelse {
-            _ = env_os.unsetenv("HOME");
-            break :env;
-        };
-        _ = env_os.setenv("HOME", home);
-        std.testing.allocator.free(home);
-    }
-    const temp_home = "/tmp/ghostty-test-home";
-    _ = env_os.setenv("HOME", temp_home);
-
     const DirCase = struct {
         name: [:0]const u8,
-        func: fn (Allocator, Options) anyerror![]u8,
+        func: fn (Allocator, *std.process.Environ.Map, Options) anyerror![]u8,
         default_subdir: []const u8,
     };
 
@@ -192,19 +180,10 @@ test "fallback when xdg env empty" {
     };
 
     inline for (cases) |case| {
-        // Save and restore each environment variable
-        const saved_env = blk: {
-            const value = std.posix.getenv(case.name) orelse break :blk null;
-            break :blk try alloc.dupeZ(u8, value);
-        };
-        defer env: {
-            const value = saved_env orelse {
-                _ = env_os.unsetenv(case.name);
-                break :env;
-            };
-            _ = env_os.setenv(case.name, value);
-            alloc.free(value);
-        }
+        var environ_map = try std.testing.environ.createMap(alloc);
+        defer environ_map.deinit();
+        const temp_home = "/tmp/ghostty-test-home";
+        try environ_map.put("HOME", temp_home);
 
         const expected = try std.fs.path.join(alloc, &[_][]const u8{
             temp_home,
@@ -213,8 +192,8 @@ test "fallback when xdg env empty" {
         defer alloc.free(expected);
 
         // Test with empty string - should fallback to home
-        _ = env_os.setenv(case.name, "");
-        const actual = try case.func(alloc, .{});
+        try environ_map.put(case.name, "");
+        const actual = try case.func(alloc, &environ_map, .{});
         defer alloc.free(actual);
 
         try std.testing.expectEqualStrings(expected, actual);
@@ -224,28 +203,11 @@ test "fallback when xdg env empty" {
 test "fallback when xdg env empty and subdir" {
     if (builtin.os.tag == .windows) return error.SkipZigTest;
 
-    const env = @import("env.zig");
     const alloc = std.testing.allocator;
 
-    const saved_home = home: {
-        const home = std.posix.getenv("HOME") orelse break :home null;
-        break :home try alloc.dupeZ(u8, home);
-    };
-    defer env: {
-        const home = saved_home orelse {
-            _ = env.unsetenv("HOME");
-            break :env;
-        };
-        _ = env.setenv("HOME", home);
-        std.testing.allocator.free(home);
-    }
-
-    const temp_home = "/tmp/ghostty-test-home";
-    _ = env.setenv("HOME", temp_home);
-
     const DirCase = struct {
         name: [:0]const u8,
-        func: fn (Allocator, Options) anyerror![]u8,
+        func: fn (Allocator, *const std.process.Environ.Map, Options) anyerror![]u8,
         default_subdir: []const u8,
     };
 
@@ -256,19 +218,10 @@ test "fallback when xdg env empty and subdir" {
     };
 
     inline for (cases) |case| {
-        // Save and restore each environment variable
-        const saved_env = blk: {
-            const value = std.posix.getenv(case.name) orelse break :blk null;
-            break :blk try alloc.dupeZ(u8, value);
-        };
-        defer env: {
-            const value = saved_env orelse {
-                _ = env.unsetenv(case.name);
-                break :env;
-            };
-            _ = env.setenv(case.name, value);
-            alloc.free(value);
-        }
+        var environ_map = try std.testing.environ.createMap(alloc);
+        defer environ_map.deinit();
+        const temp_home = "/tmp/ghostty-test-home";
+        try environ_map.put("HOME", temp_home);
 
         const expected = try std.fs.path.join(alloc, &[_][]const u8{
             temp_home,
@@ -278,8 +231,8 @@ test "fallback when xdg env empty and subdir" {
         defer alloc.free(expected);
 
         // Test with empty string - should fallback to home
-        _ = env.setenv(case.name, "");
-        const actual = try case.func(alloc, .{ .subdir = "ghostty" });
+        try environ_map.put(case.name, "");
+        const actual = try case.func(alloc, &environ_map, .{ .subdir = "ghostty" });
         defer alloc.free(actual);
 
         try std.testing.expectEqualStrings(expected, actual);
diff --git a/src/pty.zig b/src/pty.zig
index 40277a8ba..de42ef578 100644
--- a/src/pty.zig
+++ b/src/pty.zig
@@ -153,19 +153,20 @@ const PosixPty = struct {
         // Set CLOEXEC on the master fd, only the slave fd should be inherited
         // by the child process (shell/command).
         cloexec: {
-            const flags = posix.fcntl(master_fd, posix.F.GETFD, 0) catch |err| {
-                log.warn("error getting flags for master fd err={}", .{err});
+            const flags = posix.system.fcntl(master_fd, posix.F.GETFD);
+            if (flags == -1) {
+                log.warn("error getting flags for master fd err=E{s}", .{@tagName(posix.errno(-1))});
                 break :cloexec;
-            };
+            }
 
-            _ = posix.fcntl(
+            switch (posix.errno(posix.system.fcntl(
                 master_fd,
                 posix.F.SETFD,
                 flags | posix.FD_CLOEXEC,
-            ) catch |err| {
-                log.warn("error setting CLOEXEC on master fd err={}", .{err});
-                break :cloexec;
-            };
+            ))) {
+                .SUCCESS => {},
+                else => |e| log.warn("error setting CLOEXEC on master fd err=E{}", .{e}),
+            }
         }
 
         // Enable UTF-8 mode. I think this is on by default on Linux but it
@@ -260,8 +261,8 @@ const PosixPty = struct {
         }
 
         // Can close master/slave pair now
-        posix.close(self.slave);
-        posix.close(self.master);
+        _ = posix.system.close(self.slave);
+        _ = posix.system.close(self.master);
     }
 
     /// Get information about the process(es) attached to the PTY. Returns
@@ -275,9 +276,9 @@ const PosixPty = struct {
                         const linux = std.os.linux;
                         var pgrp: i32 = undefined;
                         const rc = linux.tcgetpgrp(self.master, &pgrp);
-                        switch (linux.E.init(rc)) {
-                            .SUCCESS => return @intCast(pgrp),
-                            else => return null,
+                        switch (rc) {
+                            0 => return @intCast(pgrp), // SUCCESS
+                            else => return null, // Anything else
                         }
                     },
                     else => {
@@ -334,7 +335,7 @@ const WindowsPty = struct {
     in_pipe: windows.HANDLE,
     out_pipe_pty: windows.HANDLE,
     in_pipe_pty: windows.HANDLE,
-    pseudo_console: windows.exp.HPCON,
+    pseudo_console: windows.HPCON,
     size: winsize,
 
     pub const OpenError = error{Unexpected};
@@ -367,10 +368,10 @@ const WindowsPty = struct {
             .lpSecurityDescriptor = null,
         };
 
-        pty.in_pipe = windows.kernel32.CreateNamedPipeW(
+        pty.in_pipe = windows.exp.kernel32.CreateNamedPipeW(
             pipe_path_w.ptr,
             windows.PIPE_ACCESS_OUTBOUND |
-                windows.exp.FILE_FLAG_FIRST_PIPE_INSTANCE |
+                windows.FILE_FLAG_FIRST_PIPE_INSTANCE |
                 windows.FILE_FLAG_OVERLAPPED,
             windows.PIPE_TYPE_BYTE,
             1,
@@ -380,12 +381,12 @@ const WindowsPty = struct {
             &security_attributes,
         );
         if (pty.in_pipe == windows.INVALID_HANDLE_VALUE) {
-            return windows.unexpectedError(windows.kernel32.GetLastError());
+            return windows.unexpectedError(windows.GetLastError());
         }
-        errdefer _ = windows.CloseHandle(pty.in_pipe);
+        errdefer _ = windows.exp.kernel32.CloseHandle(pty.in_pipe);
 
         var security_attributes_read = security_attributes;
-        pty.in_pipe_pty = windows.kernel32.CreateFileW(
+        pty.in_pipe_pty = windows.exp.kernel32.CreateFileW(
             pipe_path_w.ptr,
             windows.GENERIC_READ,
             0,
@@ -395,9 +396,9 @@ const WindowsPty = struct {
             null,
         );
         if (pty.in_pipe_pty == windows.INVALID_HANDLE_VALUE) {
-            return windows.unexpectedError(windows.kernel32.GetLastError());
+            return windows.unexpectedError(windows.GetLastError());
         }
-        errdefer _ = windows.CloseHandle(pty.in_pipe_pty);
+        errdefer _ = windows.exp.kernel32.CloseHandle(pty.in_pipe_pty);
 
         // The in_pipe needs to be created as a named pipe, since anonymous
         // pipes created with CreatePipe do not support overlapped operations,
@@ -414,18 +415,30 @@ const WindowsPty = struct {
         //     _ = windows.CloseHandle(pty.in_pipe);
         // }
 
-        if (windows.exp.kernel32.CreatePipe(&pty.out_pipe, &pty.out_pipe_pty, null, 0) == 0) {
-            return windows.unexpectedError(windows.kernel32.GetLastError());
+        if (windows.exp.kernel32.CreatePipe(&pty.out_pipe, &pty.out_pipe_pty, null, 0) == windows.FALSE) {
+            return windows.unexpectedError(windows.GetLastError());
         }
         errdefer {
-            _ = windows.CloseHandle(pty.out_pipe);
-            _ = windows.CloseHandle(pty.out_pipe_pty);
+            _ = windows.exp.kernel32.CloseHandle(pty.out_pipe);
+            _ = windows.exp.kernel32.CloseHandle(pty.out_pipe_pty);
         }
 
-        try windows.SetHandleInformation(pty.in_pipe, windows.HANDLE_FLAG_INHERIT, 0);
-        try windows.SetHandleInformation(pty.in_pipe_pty, windows.HANDLE_FLAG_INHERIT, 0);
-        try windows.SetHandleInformation(pty.out_pipe, windows.HANDLE_FLAG_INHERIT, 0);
-        try windows.SetHandleInformation(pty.out_pipe_pty, windows.HANDLE_FLAG_INHERIT, 0);
+        const SetHandleInformation = struct {
+            fn f(hObject: windows.HANDLE) !void {
+                if (windows.exp.kernel32.SetHandleInformation(
+                    hObject,
+                    windows.HANDLE_FLAG_INHERIT,
+                    0,
+                ) == windows.FALSE) {
+                    return windows.unexpectedError(windows.GetLastError());
+                }
+            }
+        };
+
+        try SetHandleInformation.f(pty.in_pipe);
+        try SetHandleInformation.f(pty.in_pipe_pty);
+        try SetHandleInformation.f(pty.out_pipe);
+        try SetHandleInformation.f(pty.out_pipe_pty);
 
         const result = windows.exp.kernel32.CreatePseudoConsole(
             .{ .X = @intCast(size.ws_col), .Y = @intCast(size.ws_row) },
@@ -441,10 +454,10 @@ const WindowsPty = struct {
     }
 
     pub fn deinit(self: *Pty) void {
-        _ = windows.CloseHandle(self.in_pipe_pty);
-        _ = windows.CloseHandle(self.in_pipe);
-        _ = windows.CloseHandle(self.out_pipe_pty);
-        _ = windows.CloseHandle(self.out_pipe);
+        _ = windows.exp.kernel32.CloseHandle(self.in_pipe_pty);
+        _ = windows.exp.kernel32.CloseHandle(self.in_pipe);
+        _ = windows.exp.kernel32.CloseHandle(self.out_pipe_pty);
+        _ = windows.exp.kernel32.CloseHandle(self.out_pipe);
         _ = windows.exp.kernel32.ClosePseudoConsole(self.pseudo_console);
         self.* = undefined;
     }
diff --git a/src/quirks_memset.zig b/src/quirks_memset.zig
new file mode 100644
index 000000000..6293b1c4f
--- /dev/null
+++ b/src/quirks_memset.zig
@@ -0,0 +1,322 @@
+//! Provides a fast `memset` symbol that overrides the slow scalar
+//! implementation provided by Zig 0.16's compiler_rt.
+//!
+//! Consider deleting when upstream ships an optimized compiler_rt
+//! memset (tracked by ziglang/zig#32091, maybe fixed at
+//! ziglang/zig#35754). To verify it is safe to delete, check that
+//! the disassembly of `memset` in a ReleaseFast binary is vectorized
+//! (or at least not a byte-at-a-time loop).
+//!
+//! ## Background
+//!
+//! Zig 0.16.0 globally disabled LLVM loop auto-vectorization to work
+//! around an LLVM 21 miscompilation (llvm/llvm-project#186922, see
+//! the 0.16.0 release notes). compiler_rt's memset is a naive
+//! byte-at-a-time loop that relied entirely on auto-vectorization,
+//! so it now compiles to a scalar loop roughly 24x slower than what
+//! Zig 0.15 produced.
+//!
+//! In benchmarks this made `ghostty-bench +terminal-stream` 2.8x slower on
+//! ASCII input (memset was 63% of all executed instructions!).
+//!
+//! Because compiler_rt's symbol is weak, exporting a strong `memset`
+//! from our own code transparently overrides it everywhere. The
+//! implementation below is manually vectorized with `@Vector`, which
+//! does not depend on the disabled loop vectorizer.
+//!
+//! Other mem functions deliberately not overridden:
+//!
+//! - memcpy/memmove: compiler_rt's implementations are manually
+//!   vectorized upstream ("memcpyFast") and remain fast.
+//! - memcmp/bcmp/strlen: also scalar in 0.16, but they never showed
+//!   up in our profiles.
+//!
+//! This file has no effect unless it is referenced from an artifact
+//! root (e.g. `comptime { _ = @import("quirks_memset.zig"); }`).
+//! It must NOT be imported from shared code, otherwise downstream
+//! consumers of our Zig modules would get this export injected into
+//! their binaries.
+//!
+//! ## References
+//!
+//! I referenced the musl asm + c memset implementation (MIT licensed).
+//! The primary thing I took away from that is the dc zva trick for
+//! aarch64. The remainder is fairly obvious memset work.
+
+const std = @import("std");
+const builtin = @import("builtin");
+
+comptime {
+    // Strong linkage when we control the final link (executables,
+    // shared libraries), weak otherwise.
+    const linkage: std.builtin.GlobalLinkage = switch (builtin.output_mode) {
+        .Exe => .strong,
+        .Lib => switch (builtin.link_mode) {
+            .dynamic => .strong,
+            .static => .weak,
+        },
+        .Obj => .weak,
+    };
+
+    // Whether the override is emitted:
+    //
+    //   1. On targets without SIMD we disable, since compiler_rt's
+    //      scalar operations are going to be just as good.
+    //   2. The C object format target uses strong linkage which
+    //      conflits with ours and errors.
+    //   3. Weak COFF builds fatally error because MSVC's linker
+    //      errors when two identical linked symbols exist. MSVC has
+    //      CRT which links so we don't need this there anyways.
+    const enabled =
+        std.simd.suggestVectorLength(u8) != null and
+        builtin.object_format != .c and
+        !(linkage == .weak and builtin.object_format == .coff);
+
+    if (enabled) @export(&memset, .{
+        .name = "memset",
+        .linkage = linkage,
+
+        // Hidden so that shared library builds (libghostty,
+        // libghostty-vt) resolve this internally without exporting
+        // it to their host applications.
+        .visibility = .hidden,
+    });
+}
+
+/// Bytes stored per loop iteration. Twice the native vector size so
+/// each iteration issues two vector stores (e.g. `stp q0, q0` on
+/// aarch64). Capped at 128 both because the small path below relies
+/// on len < 128 once the loop is skipped, and because wider single
+/// iterations stop paying off anyway (e.g. on scalable-vector
+/// targets that suggest very large lengths).
+const vec_bytes = @min(128, 2 * (std.simd.suggestVectorLength(u8) orelse 8));
+
+/// Whether the `dc zva` fast path for large zero fills is available.
+/// `dc zva` zeroes a whole cacheline per instruction without moving data
+/// through the store pipeline. Based on musl.
+const zva_enabled = builtin.cpu.arch == .aarch64 and
+    builtin.os.tag != .freestanding;
+
+/// Only use `dc zva` at or above this many bytes. Below this our
+/// plain vector loop measures faster. Empirically mesaured.
+const zva_threshold = 16384;
+
+/// Matches compiler_rt's memset signature (lib/compiler_rt.zig).
+fn memset(dest: ?[*]u8, c: u8, len: usize) callconv(.c) ?[*]u8 {
+    @setRuntimeSafety(false);
+
+    if (len == 0) return dest;
+    const d = dest.?;
+
+    // Large path: full-width vector stores.
+    if (len >= vec_bytes) {
+        // Very large zero fills: zero whole cachelines with `dc zva`
+        // instead. Only implemented for the (universal in practice)
+        // 64-byte block size; anything else falls through to the
+        // vector loop.
+        if (comptime zva_enabled) {
+            if (len >= zva_threshold and c == 0) zva: {
+                if (zvaSize() != 64) break :zva;
+                const splat64: @Vector(64, u8) = @splat(0);
+
+                // Head: one unaligned store covering every byte up
+                // to the first 64-aligned address (and usually a bit
+                // beyond it; the overlap is fine).
+                const addr = @intFromPtr(d);
+                const aligned = std.mem.alignForward(usize, addr, 64);
+                d[0..64].* = splat64;
+
+                // Zero whole aligned cachelines while at least one
+                // full line remains in range. `dc zva` requires the
+                // WHOLE line to be inside the buffer: it always
+                // zeroes all 64 bytes.
+                var p: [*]u8 = @ptrFromInt(aligned);
+                const end_addr = addr + len;
+                while (@intFromPtr(p) + 64 <= end_addr) : (p += 64) {
+                    asm volatile ("dc zva, %[ptr]"
+                        :
+                        : [ptr] "r" (p),
+                        : .{ .memory = true });
+                }
+
+                // Tail: overlapping unaligned store anchored to the
+                // end of the buffer, covering whatever the line loop
+                // could not. len >= zva_threshold >= 64 so this
+                // cannot underflow.
+                d[len - 64 ..][0..64].* = splat64;
+                return dest;
+            }
+        }
+
+        const splat: @Vector(vec_bytes, u8) = @splat(c);
+
+        // Fill [0, N) where N is len rounded down to a multiple of
+        // vec_bytes.
+        var i: usize = 0;
+        while (i + vec_bytes <= len) : (i += vec_bytes) {
+            d[i..][0..vec_bytes].* = splat;
+
+            // This empty asm statement prevents LLVM's
+            // LoopIdiomRecognize pass from replacing this loop with
+            // a call to memset, which would be infinite recursion
+            // since we ARE memset. compiler_rt is protected from
+            // this by being built with -fno-builtin; Ghostty is not.
+            asm volatile ("" ::: .{ .memory = true });
+        }
+
+        // Fill the remaining [N, len) tail, if any, with one more
+        // full-width store anchored to the END of the buffer. It
+        // overlaps up to vec_bytes-1 bytes that the loop already
+        // wrote, which is fine (same value), and cannot underflow
+        // because len >= vec_bytes in this path.
+        if (i != len) d[len - vec_bytes ..][0..vec_bytes].* = splat;
+        return dest;
+    }
+
+    // Small path (len < vec_bytes): pairs of narrower stores, one
+    // anchored to the start of the buffer and one to the end.
+    //
+    // The invariant for each branch below: a store of width w at
+    // [0..w] plus a store at [len-w..len] covers every byte exactly
+    // when w <= len <= 2*w. Smaller lens are handled by a later
+    // branch; larger lens by an earlier one.
+
+    comptime std.debug.assert(vec_bytes <= 128);
+    if (comptime vec_bytes > 64) {
+        if (len >= 64) {
+            // 64 <= len < vec_bytes <= 128 (asserted above): one
+            // pair of 64-byte stores covers len <= 128. Only emitted
+            // when vec_bytes > 64 (e.g. AVX-512), otherwise the
+            // vector loop above already handled these lengths.
+            const splat64: @Vector(64, u8) = @splat(c);
+            d[0..64].* = splat64;
+            d[len - 64 ..][0..64].* = splat64;
+            return dest;
+        }
+    }
+    if (len >= 16) {
+        // 16 <= len < @min(vec_bytes, 64), so at most 63. One pair
+        // of 16-byte stores covers len <= 32. For 32 < len < 64, a
+        // second pair extends the covered prefix to [0..32] and the
+        // covered suffix to [len-32..len], which meet or overlap in
+        // the middle.
+        const splat16: @Vector(16, u8) = @splat(c);
+        d[0..16].* = splat16;
+        d[len - 16 ..][0..16].* = splat16;
+        if (len > 32) {
+            d[16..32].* = splat16;
+            d[len - 32 ..][0..16].* = splat16;
+        }
+        return dest;
+    }
+    if (len >= 8) {
+        // 8 <= len <= 15: one 8-byte pair (covers len <= 16).
+        const splat8: @Vector(8, u8) = @splat(c);
+        d[0..8].* = splat8;
+        d[len - 8 ..][0..8].* = splat8;
+        return dest;
+    }
+    if (len >= 4) {
+        // 4 <= len <= 7: one 4-byte pair (covers len <= 8).
+        const splat4: @Vector(4, u8) = @splat(c);
+        d[0..4].* = splat4;
+        d[len - 4 ..][0..4].* = splat4;
+        return dest;
+    }
+
+    // 1 <= len <= 3: too short for the pair trick; write bytes one
+    // at a time. The asm statement again keeps LoopIdiomRecognize
+    // from turning this into a recursive memset call; LLVM will do
+    // that even for a loop this short because the trip count is not
+    // statically known.
+    var i: usize = 0;
+    while (i < len) : (i += 1) {
+        d[i] = c;
+        asm volatile ("" ::: .{ .memory = true });
+    }
+    return dest;
+}
+
+/// Cached `dc zva` block size: 0 = not yet queried, 1 = unavailable
+/// or prohibited, otherwise the block size in bytes. Racing threads
+/// store the same value so the memory ordering is irrelevant.
+var zva_size: std.atomic.Value(usize) = .init(0);
+
+fn zvaSize() usize {
+    const cached = zva_size.load(.monotonic);
+    if (cached != 0) return cached;
+    const dczid = asm ("mrs %[out], dczid_el0"
+        : [out] "=r" (-> u64),
+    );
+    // Bit 4 (DZP) prohibits DC ZVA; bits 0-3 are log2 of the block
+    // size in 4-byte words.
+    const size: usize = if (dczid & 0x10 != 0)
+        1
+    else
+        @as(usize, 4) << @intCast(dczid & 0xF);
+    zva_size.store(size, .monotonic);
+    return size;
+}
+
+test memset {
+    const testing = std.testing;
+
+    // A buffer larger than anything the small/vector paths special
+    // case, with room for offset (alignment) variations. Guard bytes
+    // around the fill region must remain untouched.
+    var buf: [4 * vec_bytes + 33]u8 = undefined;
+    for (0..vec_bytes + 1) |offset| {
+        for (0..buf.len - offset) |len| {
+            for ([_]u8{ 0x00, 0x5C, 0xFF }) |c| {
+                @memset(&buf, 0xAA);
+                const region = buf[offset..][0..len];
+                const ret = memset(region.ptr, c, len);
+                try testing.expectEqual(region.ptr, ret.?);
+                for (buf[0..offset]) |b| try testing.expectEqual(0xAA, b);
+                for (region) |b| try testing.expectEqual(c, b);
+                for (buf[offset + len ..]) |b| try testing.expectEqual(0xAA, b);
+            }
+        }
+    }
+
+    // Zero length must not touch memory and must tolerate null.
+    try testing.expectEqual(null, memset(null, 0x11, 0));
+    var one: [1]u8 = .{0xAA};
+    _ = memset(&one, 0x11, 0);
+    try testing.expectEqual(0xAA, one[0]);
+}
+
+test "memset large zero fills (dc zva path)" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    // Sizes at and around the ZVA threshold, with a guard byte on
+    // each side and every offset within a cacheline so the head and
+    // tail alignment handling is fully exercised.
+    const buf = try alloc.alloc(u8, 2 * zva_threshold + 66);
+    defer alloc.free(buf);
+
+    for ([_]usize{
+        zva_threshold - 1,
+        zva_threshold,
+        zva_threshold + 63,
+        2 * zva_threshold,
+    }) |len| {
+        for (0..65) |offset| {
+            @memset(buf, 0xAA);
+            const region = buf[1 + offset ..][0..len];
+            _ = memset(region.ptr, 0x00, len);
+            for (buf[0 .. 1 + offset]) |b| try testing.expectEqual(0xAA, b);
+            for (region) |b| try testing.expectEqual(0x00, b);
+            for (buf[1 + offset + len ..]) |b| try testing.expectEqual(0xAA, b);
+        }
+    }
+
+    // Nonzero fills of ZVA-eligible sizes must not take the ZVA path
+    // (it can only write zeroes).
+    @memset(buf, 0xAA);
+    _ = memset(buf.ptr + 1, 0x5C, zva_threshold);
+    try testing.expectEqual(0xAA, buf[0]);
+    for (buf[1 .. 1 + zva_threshold]) |b| try testing.expectEqual(0x5C, b);
+    try testing.expectEqual(0xAA, buf[1 + zva_threshold]);
+}
diff --git a/src/renderer/Overlay.zig b/src/renderer/Overlay.zig
index 62eb004ba..46a75be8e 100644
--- a/src/renderer/Overlay.zig
+++ b/src/renderer/Overlay.zig
@@ -20,6 +20,7 @@ const size = @import("size.zig");
 const Size = size.Size;
 const CellSize = size.CellSize;
 const Image = @import("image.zig").Image;
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.renderer_overlay);
 
@@ -337,7 +338,7 @@ fn highlightGridRect(
     const end_y: f64 = start_y + @as(f64, @floatFromInt(px_height));
 
     // Grab our context to draw
-    var ctx: z2d.Context = .init(alloc, &self.surface);
+    var ctx: z2d.Context = .init(global.io(), alloc, &self.surface);
     defer ctx.deinit();
 
     // Don't need AA because we use sharp edges
@@ -394,7 +395,7 @@ fn highlightPixelRect(
     const end_x: f64 = start_x + @as(f64, @floatFromInt(px_width));
     const end_y: f64 = start_y + @as(f64, @floatFromInt(px_height));
 
-    var ctx: z2d.Context = .init(alloc, &self.surface);
+    var ctx: z2d.Context = .init(global.io(), alloc, &self.surface);
     defer ctx.deinit();
 
     ctx.setAntiAliasingMode(.none);
diff --git a/src/renderer/State.zig b/src/renderer/State.zig
index 8693458f1..1e38d64a9 100644
--- a/src/renderer/State.zig
+++ b/src/renderer/State.zig
@@ -14,7 +14,7 @@ const renderer = @import("../renderer.zig");
 /// members of this state. Note that the state itself is NOT protected
 /// by the mutex and is NOT thread-safe, only the members values of the
 /// state (i.e. the terminal, devmode, etc. values).
-mutex: *std.Thread.Mutex,
+mutex: *std.Io.Mutex,
 
 /// The terminal data.
 terminal: *terminalpkg.Terminal,
@@ -64,19 +64,19 @@ const handoff_timeout_ns = 1 * std.time.ns_per_ms;
 /// scheduled. Under sustained pty output the IO parse thread is
 /// exactly such a loop, so without this signal the renderer can
 /// starve for as long as the output lasts.
-pub fn lockDemand(self: *State) void {
+pub fn lockDemand(self: *State, io: std.Io) void {
     _ = self.demand.fetchAdd(1, .monotonic);
-    self.mutex.lock();
+    self.mutex.lockUncancelable(io);
     const prev = self.demand.fetchSub(1, .monotonic);
     assert(prev > 0);
 }
 
 /// Release `mutex` acquired via `lockDemand` and notify hot loops
 /// parked in `yieldToDemand` that the demanding waiter had its turn.
-pub fn unlockDemand(self: *State) void {
-    self.mutex.unlock();
+pub fn unlockDemand(self: *State, io: std.Io) void {
+    self.mutex.unlock(io);
     _ = self.handoff_gen.fetchAdd(1, .monotonic);
-    std.Thread.Futex.wake(&self.handoff_gen, 1);
+    io.futexWake(@TypeOf(self.handoff_gen), &self.handoff_gen, 1);
 }
 
 /// Called by hot lock/unlock loops between critical sections, with
@@ -88,7 +88,7 @@ pub fn unlockDemand(self: *State) void {
 /// scheduling heuristic, not a synchronization boundary: the mutex
 /// itself orders the protected data, and the timeout bounds any
 /// staleness.
-pub fn yieldToDemand(self: *State) void {
+pub fn yieldToDemand(self: *State, io: std.Io) void {
     if (self.demand.load(.monotonic) == 0) return;
 
     // Snapshot the generation before rechecking demand: if the waiter
@@ -96,10 +96,11 @@ pub fn yieldToDemand(self: *State) void {
     // generation no longer matches and timedWait returns immediately.
     const gen = self.handoff_gen.load(.monotonic);
     if (self.demand.load(.monotonic) == 0) return;
-    std.Thread.Futex.timedWait(
+    io.futexWaitTimeout(
+        @TypeOf(self.handoff_gen),
         &self.handoff_gen,
-        gen,
-        handoff_timeout_ns,
+        .init(gen),
+        .{ .duration = .{ .raw = .fromNanoseconds(handoff_timeout_ns), .clock = .awake } },
     ) catch {};
 }
 
diff --git a/src/renderer/Thread.zig b/src/renderer/Thread.zig
index e397a55a1..4b2b741d8 100644
--- a/src/renderer/Thread.zig
+++ b/src/renderer/Thread.zig
@@ -4,7 +4,8 @@ pub const Thread = @This();
 
 const std = @import("std");
 const builtin = @import("builtin");
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 const crash = @import("../crash/main.zig");
 const internal_os = @import("../os/main.zig");
 const rendererpkg = @import("../renderer.zig");
@@ -361,7 +362,7 @@ fn drainMailbox(self: *Thread) !void {
         void;
     defer if (builtin.os.tag.isDarwin()) pool.deinit();
 
-    while (self.mailbox.pop()) |message| {
+    while (self.mailbox.pop(global.io())) |message| {
         log.debug("mailbox message={}", .{message});
         switch (message) {
             .crash => @panic("crash request, crashing intentionally"),
@@ -788,7 +789,7 @@ const Compression = struct {
         // frame without changing terminal contents and must not starve this
         // timer indefinitely.
         if (thread.state.mutex.tryLock()) {
-            defer thread.state.mutex.unlock();
+            defer thread.state.mutex.unlock(global.io());
             const activity = thread.state.terminal.compressionActivity();
             if (self.activity == activity) return;
             self.activity = activity;
@@ -847,7 +848,7 @@ const Compression = struct {
 
         const state = thread.state;
         if (!state.mutex.tryLock()) return idle_interval;
-        defer state.mutex.unlock();
+        defer state.mutex.unlock(global.io());
 
         const activity = state.terminal.compressionActivity();
         if (self.activity != activity) {
diff --git a/src/renderer/cell.zig b/src/renderer/cell.zig
index 196ebb175..b9880fbde 100644
--- a/src/renderer/cell.zig
+++ b/src/renderer/cell.zig
@@ -510,7 +510,7 @@ test "Cell constraint widths" {
     const testing = std.testing;
     const alloc = testing.allocator;
 
-    var t: terminal.Terminal = try .init(alloc, .{
+    var t: terminal.Terminal = try .init(testing.io, alloc, .{
         .cols = 4,
         .rows = 1,
     });
diff --git a/src/renderer/cursor.zig b/src/renderer/cursor.zig
index 33992bc55..3314db29f 100644
--- a/src/renderer/cursor.zig
+++ b/src/renderer/cursor.zig
@@ -70,7 +70,8 @@ pub fn style(
 test "cursor: default uses configured style" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var term: terminal.Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var term: terminal.Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer term.deinit(alloc);
 
     term.screens.active.cursor.cursor_style = .bar;
@@ -89,7 +90,8 @@ test "cursor: default uses configured style" {
 test "cursor: blinking disabled" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var term = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var term = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer term.deinit(alloc);
 
     term.screens.active.cursor.cursor_style = .bar;
@@ -108,7 +110,8 @@ test "cursor: blinking disabled" {
 test "cursor: explicitly not visible" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var term = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var term = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer term.deinit(alloc);
 
     term.screens.active.cursor.cursor_style = .bar;
@@ -128,7 +131,8 @@ test "cursor: explicitly not visible" {
 test "cursor: always block with preedit" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var term = try terminal.Terminal.init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var term = try terminal.Terminal.init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer term.deinit(alloc);
 
     var state: terminal.RenderState = .empty;
diff --git a/src/renderer/generic.zig b/src/renderer/generic.zig
index 14b790369..e0760fce1 100644
--- a/src/renderer/generic.zig
+++ b/src/renderer/generic.zig
@@ -26,6 +26,8 @@ const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
 const Terminal = terminal.Terminal;
 const Health = renderer.Health;
+const compat_file = @import("../lib/compat/file.zig");
+const global = @import("../global.zig");
 
 const getConstraint = @import("../font/nerd_font_attributes.zig").getConstraint;
 
@@ -98,7 +100,7 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
         /// This mutex must be held whenever any state used in `drawFrame` is
         /// being modified, and also when it's being accessed in `drawFrame`.
-        draw_mutex: std.Thread.Mutex = .{},
+        draw_mutex: std.Io.Mutex = .init,
 
         /// The configuration we need derived from the main config.
         config: DerivedConfig,
@@ -161,12 +163,12 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
         /// Timestamp we rendered out first frame.
         ///
         /// This is used when updating custom shader uniforms.
-        first_frame_time: ?std.time.Instant = null,
+        first_frame_time: ?std.Io.Timestamp = null,
 
         /// Timestamp when we rendered out more recent frame.
         ///
         /// This is used when updating custom shader uniforms.
-        last_frame_time: ?std.time.Instant = null,
+        last_frame_time: ?std.Io.Timestamp = null,
 
         /// The font structures.
         font_grid: *font.SharedGrid,
@@ -252,7 +254,7 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             frame_index: std.math.IntFittingRange(0, buf_count) = 0,
             /// Semaphore that we wait on to make sure we have an available
             /// frame state struct so we can start working on a new frame.
-            frame_sema: std.Thread.Semaphore = .{ .permits = buf_count },
+            frame_sema: std.Io.Semaphore = .{ .permits = buf_count },
 
             /// Set to true when deinited, if you try to deinit a defunct
             /// swap chain it will just be ignored, to prevent double-free.
@@ -279,7 +281,9 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
                 // Wait for all of our inflight draws to complete
                 // so that we can cleanly deinit our GPU state.
-                for (0..buf_count) |_| self.frame_sema.wait();
+                for (0..buf_count) |_| self.frame_sema.waitUncancelable(
+                    global.io(),
+                );
                 for (&self.frames) |*frame| frame.deinit();
             }
 
@@ -289,7 +293,7 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             pub fn nextFrame(self: *SwapChain) error{Defunct}!*FrameState {
                 if (self.defunct) return error.Defunct;
 
-                self.frame_sema.wait();
+                self.frame_sema.waitUncancelable(global.io());
                 errdefer self.frame_sema.post();
                 self.frame_index = (self.frame_index + 1) % buf_count;
                 return &self.frames[self.frame_index];
@@ -297,7 +301,7 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
             /// This should be called when the frame has completed drawing.
             pub fn releaseFrame(self: *SwapChain) void {
-                self.frame_sema.post();
+                self.frame_sema.post(global.io());
             }
         };
 
@@ -682,8 +686,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
                 metrics: font.Metrics,
             } = font_critical: {
                 const grid: *font.SharedGrid = options.font_grid;
-                grid.lock.lockShared();
-                defer grid.lock.unlockShared();
+                grid.lock.lockSharedUncancelable(global.io());
+                defer grid.lock.unlockShared(global.io());
                 break :font_critical .{
                     .metrics = grid.metrics,
                 };
@@ -943,8 +947,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
             // Lock the draw mutex so that we can
             // safely reinitialize our GPU resources.
-            self.draw_mutex.lock();
-            defer self.draw_mutex.unlock();
+            self.draw_mutex.lockUncancelable(global.io());
+            defer self.draw_mutex.unlock(global.io());
 
             // We assume that the swap chain was deinited in
             // `displayUnrealized`, in which case it should be
@@ -972,8 +976,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
             // Lock the draw mutex so that we can
             // safely deinitialize our GPU resources.
-            self.draw_mutex.lock();
-            defer self.draw_mutex.unlock();
+            self.draw_mutex.lockUncancelable(global.io());
+            defer self.draw_mutex.unlock(global.io());
 
             // We deinit our swap chain and shaders.
             //
@@ -1068,8 +1072,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
         ///
         /// Must be called on the render thread.
         pub fn setFontGrid(self: *Self, grid: *font.SharedGrid) void {
-            self.draw_mutex.lock();
-            defer self.draw_mutex.unlock();
+            self.draw_mutex.lockUncancelable(global.io());
+            defer self.draw_mutex.unlock(global.io());
 
             // Update our grid
             self.font_grid = grid;
@@ -1125,16 +1129,6 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             state: *renderer.State,
             cursor_blink_visible: bool,
         ) Allocator.Error!void {
-            // const start = std.time.Instant.now() catch unreachable;
-            // const start_micro = std.time.microTimestamp();
-            // defer {
-            //     const end = std.time.Instant.now() catch unreachable;
-            //     log.warn(
-            //         "[updateFrame time] start_micro={} duration={}ns",
-            //         .{ start_micro, end.since(start) / std.time.ns_per_us },
-            //     );
-            // }
-
             // We fully deinit and reset the terminal state every so often
             // so that a particularly large terminal state doesn't cause
             // the renderer to hold on to retained memory.
@@ -1163,6 +1157,9 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
             // Update all our data as tightly as possible within the mutex.
             var critical: Critical = critical: {
+                // NOTE: This code needs be updated to 0.16.0 before you
+                // un-comment it ;)
+                //
                 // const start = try std.time.Instant.now();
                 // const start_micro = std.time.microTimestamp();
                 // defer {
@@ -1170,10 +1167,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
                 //     std.log.err("[updateFrame critical time] start={}\tduration={} us", .{ start_micro, end.since(start) / std.time.ns_per_us });
                 // }
 
-                // Lock while signaling demand so the IO parse thread
-                // can't starve us. See renderer.State.lockDemand.
-                state.lockDemand();
-                defer state.unlockDemand();
+                state.lockDemand(global.io());
+                defer state.unlockDemand(global.io());
 
                 // If we're in a synchronized output state, we pause all rendering.
                 if (state.terminal.modes.get(.synchronized_output)) {
@@ -1240,8 +1235,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
                 if (self.images.kittyRequiresUpdate(state.terminal)) {
                     // We need to grab the draw mutex since this updates
                     // our image state that drawFrame uses.
-                    self.draw_mutex.lock();
-                    defer self.draw_mutex.unlock();
+                    self.draw_mutex.lockUncancelable(global.io());
+                    defer self.draw_mutex.unlock(global.io());
                     self.images.kittyUpdate(
                         self.alloc,
                         state.terminal,
@@ -1371,8 +1366,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
             // Acquire the draw mutex for all remaining state updates.
             {
-                self.draw_mutex.lock();
-                defer self.draw_mutex.unlock();
+                self.draw_mutex.lockUncancelable(global.io());
+                defer self.draw_mutex.unlock(global.io());
 
                 // Build our GPU cells
                 self.rebuildCells(
@@ -1445,20 +1440,10 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             self: *Self,
             sync: bool,
         ) !void {
-            // const start = std.time.Instant.now() catch unreachable;
-            // const start_micro = std.time.microTimestamp();
-            // defer {
-            //     const end = std.time.Instant.now() catch unreachable;
-            //     log.warn(
-            //         "[drawFrame time] start_micro={} duration={}ns",
-            //         .{ start_micro, end.since(start) / std.time.ns_per_us },
-            //     );
-            // }
-
             // We hold a the draw mutex to prevent changes to any
             // data we access while we're in the middle of drawing.
-            self.draw_mutex.lock();
-            defer self.draw_mutex.unlock();
+            self.draw_mutex.lockUncancelable(global.io());
+            defer self.draw_mutex.unlock(global.io());
 
             // After the graphics API is complete (so we defer) we want to
             // update our scrollbar state.
@@ -1585,16 +1570,16 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             texture: {
                 const modified = self.font_grid.atlas_grayscale.modified.load(.monotonic);
                 if (modified <= frame.grayscale_modified) break :texture;
-                self.font_grid.lock.lockShared();
-                defer self.font_grid.lock.unlockShared();
+                self.font_grid.lock.lockSharedUncancelable(global.io());
+                defer self.font_grid.lock.unlockShared(global.io());
                 frame.grayscale_modified = self.font_grid.atlas_grayscale.modified.load(.monotonic);
                 try self.syncAtlasTexture(&self.font_grid.atlas_grayscale, &frame.grayscale);
             }
             texture: {
                 const modified = self.font_grid.atlas_color.modified.load(.monotonic);
                 if (modified <= frame.color_modified) break :texture;
-                self.font_grid.lock.lockShared();
-                defer self.font_grid.lock.unlockShared();
+                self.font_grid.lock.lockSharedUncancelable(global.io());
+                defer self.font_grid.lock.unlockShared(global.io());
                 frame.color_modified = self.font_grid.atlas_color.modified.load(.monotonic);
                 try self.syncAtlasTexture(&self.font_grid.atlas_color, &frame.color);
             }
@@ -1766,17 +1751,22 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
                 };
 
                 // Open the file
-                var file = std.fs.openFileAbsolute(path, .{}) catch |err| {
+                var file = std.Io.Dir.openFileAbsolute(
+                    global.io(),
+                    path,
+                    .{},
+                ) catch |err| {
                     log.warn(
                         "error opening background image file \"{s}\": {}",
                         .{ path, err },
                     );
                     break :load_background;
                 };
-                defer file.close();
+                defer file.close(global.io());
 
                 // Read it
-                const contents = file.readToEndAlloc(
+                const contents = compat_file.readToEndAlloc(
+                    file,
                     self.alloc,
                     std.math.maxInt(u32), // Max size of 4 GiB, for now.
                 ) catch |err| {
@@ -1853,8 +1843,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
         /// Update the configuration.
         pub fn changeConfig(self: *Self, config: *DerivedConfig) !void {
-            self.draw_mutex.lock();
-            defer self.draw_mutex.unlock();
+            self.draw_mutex.lockUncancelable(global.io());
+            defer self.draw_mutex.unlock(global.io());
 
             // We always redo the font shaper in case font features changed. We
             // could check to see if there was an actual config change but this is
@@ -1934,8 +1924,8 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             self: *Self,
             size: renderer.Size,
         ) void {
-            self.draw_mutex.lock();
-            defer self.draw_mutex.unlock();
+            self.draw_mutex.lockUncancelable(global.io());
+            defer self.draw_mutex.unlock(global.io());
 
             // We only actually need the padding from this,
             // everything else is derived elsewhere.
@@ -2119,7 +2109,7 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
 
             const uniforms: *shadertoy.Uniforms = &self.custom_shader_uniforms;
 
-            const now = try std.time.Instant.now();
+            const now: std.Io.Timestamp = .now(global.io(), .awake);
             defer self.last_frame_time = now;
             const first_frame_time = self.first_frame_time orelse t: {
                 self.first_frame_time = now;
@@ -2127,10 +2117,10 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             };
             const last_frame_time = self.last_frame_time orelse now;
 
-            const since_ns: f32 = @floatFromInt(now.since(first_frame_time));
+            const since_ns: f32 = @floatFromInt(first_frame_time.durationTo(now).nanoseconds);
             uniforms.time = since_ns / std.time.ns_per_s;
 
-            const delta_ns: f32 = @floatFromInt(now.since(last_frame_time));
+            const delta_ns: f32 = @floatFromInt(last_frame_time.durationTo(now).nanoseconds);
             uniforms.time_delta = delta_ns / std.time.ns_per_s;
 
             uniforms.frame += 1;
@@ -2241,16 +2231,6 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             self: *Self,
             features: []const Overlay.Feature,
         ) Overlay.InitError!void {
-            // const start = std.time.Instant.now() catch unreachable;
-            // const start_micro = std.time.microTimestamp();
-            // defer {
-            //     const end = std.time.Instant.now() catch unreachable;
-            //     log.warn(
-            //         "[rebuildOverlay time] start_micro={} duration={}ns",
-            //         .{ start_micro, end.since(start) / std.time.ns_per_us },
-            //     );
-            // }
-
             const alloc = self.alloc;
 
             // If we have no features enabled, don't build an overlay.
@@ -2326,14 +2306,6 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
         ) Allocator.Error!void {
             const state: *terminal.RenderState = &self.terminal_state;
 
-            // const start = try std.time.Instant.now();
-            // const start_micro = std.time.microTimestamp();
-            // defer {
-            //     const end = std.time.Instant.now() catch unreachable;
-            //     // "[rebuildCells time] <START us>\t<TIME_TAKEN us>"
-            //     std.log.warn("[rebuildCells time] {}\t{}", .{start_micro, end.since(start) / std.time.ns_per_us});
-            // }
-
             const grid_size_diff =
                 self.cells.size.rows != state.rows or
                 self.cells.size.columns != state.cols;
diff --git a/src/renderer/image.zig b/src/renderer/image.zig
index f8269354a..dc5e3e228 100644
--- a/src/renderer/image.zig
+++ b/src/renderer/image.zig
@@ -3,6 +3,7 @@ const Allocator = std.mem.Allocator;
 const assert = @import("../quirks.zig").inlineAssert;
 const wuffs = @import("wuffs");
 const terminal = @import("../terminal/main.zig");
+const global = @import("../global.zig");
 
 const Renderer = @import("../renderer.zig").Renderer;
 const GraphicsAPI = Renderer.API;
@@ -194,7 +195,7 @@ pub const State = struct {
 
         // Overlays are always considered new content, so we take a
         // fresh generation stamp to force replacing any existing one.
-        const generation = terminal.kitty.graphics.nextGeneration();
+        const generation = terminal.kitty.graphics.nextGeneration(global.io());
 
         // Ensure we have space for our overlay placement. Do this before
         // we upload our image so we don't have to deal with cleaning
diff --git a/src/renderer/link.zig b/src/renderer/link.zig
index 11ecc87ae..dfc6fe671 100644
--- a/src/renderer/link.zig
+++ b/src/renderer/link.zig
@@ -148,7 +148,7 @@ test "renderCellMap" {
     const testing = std.testing;
     const alloc = testing.allocator;
 
-    var t: terminal.Terminal = try .init(alloc, .{
+    var t: terminal.Terminal = try .init(testing.io, alloc, .{
         .cols = 5,
         .rows = 3,
     });
@@ -201,7 +201,7 @@ test "renderCellMap hover links" {
     const testing = std.testing;
     const alloc = testing.allocator;
 
-    var t: terminal.Terminal = try .init(alloc, .{
+    var t: terminal.Terminal = try .init(testing.io, alloc, .{
         .cols = 5,
         .rows = 3,
     });
@@ -278,8 +278,9 @@ test "renderCellMap hover links" {
 test "renderCellMap inactive links don't allocate" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t: terminal.Terminal = try .init(alloc, .{
+    var t: terminal.Terminal = try .init(io, alloc, .{
         .cols = 5,
         .rows = 3,
     });
@@ -338,7 +339,7 @@ test "renderCellMap mods no match" {
     const testing = std.testing;
     const alloc = testing.allocator;
 
-    var t: terminal.Terminal = try .init(alloc, .{
+    var t: terminal.Terminal = try .init(testing.io, alloc, .{
         .cols = 5,
         .rows = 3,
     });
diff --git a/src/renderer/metal/api.zig b/src/renderer/metal/api.zig
index a2d8a1356..8c195e0f3 100644
--- a/src/renderer/metal/api.zig
+++ b/src/renderer/metal/api.zig
@@ -43,9 +43,7 @@ pub const MTLResourceOptions = packed struct(c_ulong) {
     /// https://developer.apple.com/documentation/metal/mtlhazardtrackingmode?language=objc
     hazard_tracking_mode: HazardTrackingMode = .default,
 
-    _pad: @Type(.{
-        .int = .{ .signedness = .unsigned, .bits = @bitSizeOf(c_ulong) - 10 },
-    }) = 0,
+    _pad: @Int(.unsigned, @bitSizeOf(c_ulong) - 10) = 0,
 
     pub const CPUCacheMode = enum(u4) {
         default = 0,
@@ -366,10 +364,7 @@ pub const MTLTextureUsage = packed struct(c_ulong) {
     /// https://developer.apple.com/documentation/metal/mtltextureusage/shaderatomic?language=objc
     shader_atomic: bool = false, // TextureUsageShaderAtomic = 32,
 
-    __reserved: @Type(.{ .int = .{
-        .signedness = .unsigned,
-        .bits = @bitSizeOf(c_ulong) - 6,
-    } }) = 0,
+    __reserved: @Int(.unsigned, @bitSizeOf(c_ulong) - 6) = 0,
 
     /// https://developer.apple.com/documentation/metal/mtltextureusage/unknown?language=objc
     const unknown: MTLTextureUsage = @bitCast(0); // TextureUsageUnknown = 0,
diff --git a/src/renderer/metal/shaders.zig b/src/renderer/metal/shaders.zig
index 0be023572..6ae321068 100644
--- a/src/renderer/metal/shaders.zig
+++ b/src/renderer/metal/shaders.zig
@@ -3,6 +3,7 @@ const Allocator = std.mem.Allocator;
 const macos = @import("macos");
 const objc = @import("objc");
 const math = @import("../../math.zig");
+const global = @import("../../global.zig");
 
 const mtl = @import("api.zig");
 const Pipeline = @import("Pipeline.zig");
@@ -76,22 +77,16 @@ const PipelineDescription = struct {
 
 /// We create a type for the pipeline collection based on our desc array.
 const PipelineCollection = t: {
-    var fields: [pipeline_descs.len]std.builtin.Type.StructField = undefined;
-    for (pipeline_descs, 0..) |pipeline, i| {
-        fields[i] = .{
-            .name = pipeline[0],
-            .type = Pipeline,
-            .default_value_ptr = null,
-            .is_comptime = false,
-            .alignment = @alignOf(Pipeline),
-        };
+    const StructField = std.builtin.Type.StructField;
+
+    var names: [pipeline_descs.len][]const u8 = undefined;
+    var types = [_]type{Pipeline} ** pipeline_descs.len;
+    var attrs = [_]StructField.Attributes{.{ .@"align" = @alignOf(Pipeline) }} ** pipeline_descs.len;
+
+    for (pipeline_descs, &names) |pipeline, *name| {
+        name.* = pipeline[0];
     }
-    break :t @Type(.{ .@"struct" = .{
-        .layout = .auto,
-        .fields = &fields,
-        .decls = &.{},
-        .is_tuple = false,
-    } });
+    break :t @Struct(.auto, null, &names, &types, &attrs);
 };
 
 /// This contains the state for the shaders used by the Metal renderer.
@@ -332,7 +327,7 @@ pub const BgImage = extern struct {
 
 /// Initialize the MTLLibrary. A MTLLibrary is a collection of shaders.
 fn initLibrary(device: objc.Object) !objc.Object {
-    const start = try std.time.Instant.now();
+    const start: std.Io.Timestamp = .now(global.io(), .awake);
 
     const data = try macos.dispatch.Data.create(
         @embedFile("ghostty_metallib"),
@@ -352,8 +347,7 @@ fn initLibrary(device: objc.Object) !objc.Object {
     );
     try checkError(err);
 
-    const end = try std.time.Instant.now();
-    log.debug("shader library loaded time={}us", .{end.since(start) / std.time.ns_per_us});
+    log.debug("shader library loaded time={}us", .{start.untilNow(global.io(), .awake).toMicroseconds()});
 
     return library;
 }
diff --git a/src/renderer/opengl/shaders.zig b/src/renderer/opengl/shaders.zig
index 68c1f36a3..68d2babf6 100644
--- a/src/renderer/opengl/shaders.zig
+++ b/src/renderer/opengl/shaders.zig
@@ -63,22 +63,16 @@ const PipelineDescription = struct {
 
 /// We create a type for the pipeline collection based on our desc array.
 const PipelineCollection = t: {
-    var fields: [pipeline_descs.len]std.builtin.Type.StructField = undefined;
-    for (pipeline_descs, 0..) |pipeline, i| {
-        fields[i] = .{
-            .name = pipeline[0],
-            .type = Pipeline,
-            .default_value_ptr = null,
-            .is_comptime = false,
-            .alignment = @alignOf(Pipeline),
-        };
+    const StructField = std.builtin.Type.StructField;
+
+    var names: [pipeline_descs.len][]const u8 = undefined;
+    var types = [_]type{Pipeline} ** pipeline_descs.len;
+    var attrs = [_]StructField.Attributes{.{ .@"align" = @alignOf(Pipeline) }} ** pipeline_descs.len;
+
+    for (pipeline_descs, &names) |pipeline, *name| {
+        name.* = pipeline[0];
     }
-    break :t @Type(.{ .@"struct" = .{
-        .layout = .auto,
-        .fields = &fields,
-        .decls = &.{},
-        .is_tuple = false,
-    } });
+    break :t @Struct(.auto, null, &names, &types, &attrs);
 };
 
 /// This contains the state for the shaders used by the Metal renderer.
diff --git a/src/renderer/shadertoy.zig b/src/renderer/shadertoy.zig
index 556c28293..6dee18b04 100644
--- a/src/renderer/shadertoy.zig
+++ b/src/renderer/shadertoy.zig
@@ -5,6 +5,8 @@ const ArenaAllocator = std.heap.ArenaAllocator;
 const glslang = @import("glslang");
 const spvcross = @import("spirv_cross");
 const configpkg = @import("../config.zig");
+const compat_file = @import("../lib/compat/file.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.shadertoy);
 
@@ -87,11 +89,11 @@ pub fn loadFromFile(
     // Read it all into memory -- we don't expect shaders to be large.
     const src = src: {
         // Load the shader file
-        const cwd = std.fs.cwd();
-        const file = try cwd.openFile(path, .{});
-        defer file.close();
-
-        break :src try file.readToEndAlloc(
+        const cwd = std.Io.Dir.cwd();
+        const file = try cwd.openFile(global.io(), path, .{});
+        defer file.close(global.io());
+        break :src try compat_file.readToEndAlloc(
+            file,
             alloc,
             4 * 1024 * 1024, // 4MB
         );
diff --git a/src/simd/main.zig b/src/simd/main.zig
index aabdd21d1..8a3f00670 100644
--- a/src/simd/main.zig
+++ b/src/simd/main.zig
@@ -9,6 +9,18 @@ pub const index_of = @import("index_of.zig");
 pub const vt = @import("vt.zig");
 pub const codepointWidth = codepoint_width.codepointWidth;
 
+/// The number of vector lanes to use for manually vectorized hot
+/// loops operating on elements of type T, or null if the target has
+/// no usable SIMD support and a plain scalar loop should be used
+/// instead (e.g. wasm32 without simd128).
+///
+/// This is twice the native vector width so that each iteration works
+/// two vector registers, giving better instruction-level parallelism.
+pub fn lanes(comptime T: type) ?comptime_int {
+    const native = std.simd.suggestVectorLength(T) orelse return null;
+    return native * 2;
+}
+
 test {
     @import("std").testing.refAllDecls(@This());
 }
diff --git a/src/synthetic/cli.zig b/src/synthetic/cli.zig
index d6ec028f7..dcac0d0dc 100644
--- a/src/synthetic/cli.zig
+++ b/src/synthetic/cli.zig
@@ -30,22 +30,23 @@ pub const Action = enum {
 };
 
 /// An entrypoint for the synthetic generator CLI.
-pub fn main() !void {
+pub fn main(init: std.process.Init) !void {
     const alloc = std.heap.c_allocator;
-    const action_ = try cli.action.detectArgs(Action, alloc);
+    const action_ = try cli.action.detectArgs(Action, alloc, init.minimal.args);
     const action = action_ orelse return error.NoAction;
-    try mainAction(alloc, action, .cli);
+    try mainAction(init.io, alloc, action, .{ .cli = init.minimal.args });
 }
 
 pub const Args = union(enum) {
     /// The arguments passed to the CLI via argc/argv.
-    cli,
+    cli: std.process.Args,
 
-    /// Simple string arguments, parsed via std.process.ArgIteratorGeneral.
+    /// Simple string arguments, parsed via ArgIteratorGeneral.
     string: []const u8,
 };
 
 pub fn mainAction(
+    io: std.Io,
     alloc: Allocator,
     action: Action,
     args: Args,
@@ -53,13 +54,14 @@ pub fn mainAction(
     switch (action) {
         inline else => |comptime_action| {
             const Impl = Action.Struct(comptime_action);
-            try mainActionImpl(Impl, alloc, args);
+            try mainActionImpl(Impl, io, alloc, args);
         },
     }
 }
 
 fn mainActionImpl(
     comptime Impl: type,
+    io: std.Io,
     alloc: Allocator,
     args: Args,
 ) !void {
@@ -68,13 +70,13 @@ fn mainActionImpl(
     var opts: Options = .{};
     defer if (@hasDecl(Options, "deinit")) opts.deinit();
     switch (args) {
-        .cli => {
-            var iter = try cli.args.argsIterator(alloc);
+        .cli => |process_args| {
+            var iter = try cli.args.argsIterator(alloc, process_args);
             defer iter.deinit();
             try cli.args.parse(Options, alloc, &opts, &iter);
         },
         .string => |str| {
-            var iter = try std.process.ArgIteratorGeneral(.{}).init(
+            var iter = try std.process.Args.IteratorGeneral(.{}).init(
                 alloc,
                 str,
             );
@@ -84,16 +86,13 @@ fn mainActionImpl(
     }
 
     // TODO: Make this a command line option.
-    const seed: u64 = @truncate(@as(
-        u128,
-        @bitCast(std.time.nanoTimestamp()),
-    ));
+    const seed: u64 = @truncate(@as(u96, @bitCast(std.Io.Timestamp.now(io, .real).toNanoseconds())));
     var prng = std.Random.DefaultPrng.init(seed);
     const rand = prng.random();
 
     // Our output always goes to stdout.
     var buffer: [2048]u8 = undefined;
-    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    var stdout_writer = std.Io.File.stdout().writer(io, &buffer);
     const writer = &stdout_writer.interface;
 
     // Create our implementation
diff --git a/src/synthetic/cli/Ascii.zig b/src/synthetic/cli/Ascii.zig
index d416189ce..81a4e6073 100644
--- a/src/synthetic/cli/Ascii.zig
+++ b/src/synthetic/cli/Ascii.zig
@@ -46,7 +46,6 @@ pub fn run(_: *Ascii, writer: *std.Io.Writer, rand: std.Random) !void {
             switch (@as(Error, err)) {
                 error.BrokenPipe => return, // stdout closed
                 error.WriteFailed => return, // fixed buffer full
-                else => return err,
             }
         };
     }
diff --git a/src/synthetic/cli/Utf8.zig b/src/synthetic/cli/Utf8.zig
index 021dbe516..8391627ac 100644
--- a/src/synthetic/cli/Utf8.zig
+++ b/src/synthetic/cli/Utf8.zig
@@ -86,7 +86,6 @@ pub fn run(self: *Utf8, writer: *std.Io.Writer, rand: std.Random) !void {
             switch (@as(Error, err)) {
                 error.BrokenPipe => return, // stdout closed
                 error.WriteFailed => return, // fixed buffer full
-                else => return err,
             }
         };
     }
diff --git a/src/terminal/PageList.zig b/src/terminal/PageList.zig
index a7c02bda7..79e46e5c8 100644
--- a/src/terminal/PageList.zig
+++ b/src/terminal/PageList.zig
@@ -294,7 +294,7 @@ const Node = struct {
 };
 
 /// The memory pool we get page nodes from.
-const NodePool = std.heap.MemoryPool(List.Node);
+const NodePool = std.heap.memory_pool.Managed(List.Node);
 
 /// The standard page capacity that we use as a starting point for
 /// all pages. This is chosen as a sane default that fits most terminal
@@ -307,7 +307,7 @@ const std_size = Page.layout(std_capacity).total_size;
 /// The memory pool we use for page memory buffers. We use a separate pool
 /// so we can allocate these with a page allocator. We have to use a page
 /// allocator because we need memory that is zero-initialized and page-aligned.
-const PagePool = std.heap.MemoryPoolAligned(
+const PagePool = std.heap.memory_pool.AlignedManaged(
     [std_size]u8,
     .fromByteUnits(std.heap.page_size_min),
 );
@@ -315,7 +315,7 @@ const PagePool = std.heap.MemoryPoolAligned(
 /// List of pins, known as "tracked" pins. These are pins that are kept
 /// up to date automatically through page-modifying operations.
 const PinSet = std.AutoArrayHashMapUnmanaged(*Pin, void);
-const PinPool = std.heap.MemoryPool(Pin);
+const PinPool = std.heap.memory_pool.Managed(Pin);
 
 /// The pool of memory used for a pagelist. This can be shared between
 /// multiple pagelists but it is not threadsafe.
@@ -332,11 +332,11 @@ pub const MemoryPool = struct {
         page_alloc: Allocator,
         preheat: usize,
     ) Allocator.Error!MemoryPool {
-        var node_pool = try NodePool.initPreheated(gen_alloc, preheat);
+        var node_pool = try NodePool.initCapacity(gen_alloc, preheat);
         errdefer node_pool.deinit();
-        var page_pool = try PagePool.initPreheated(page_alloc, preheat);
+        var page_pool = try PagePool.initCapacity(page_alloc, preheat);
         errdefer page_pool.deinit();
-        var pin_pool = try PinPool.initPreheated(gen_alloc, 8);
+        var pin_pool = try PinPool.initCapacity(gen_alloc, 8);
         errdefer pin_pool.deinit();
         return .{
             .alloc = gen_alloc,
@@ -696,7 +696,7 @@ fn initPages(
     const cap = initialCapacity(cols);
     const layout = Page.layout(cap);
     const pooled = layout.total_size <= std_size;
-    const page_alloc = pool.pages.arena.child_allocator;
+    const page_alloc = pool.pages.allocator;
 
     // Guaranteed by comptime checks in initialCapacity but
     // redundant here for safety.
@@ -895,7 +895,7 @@ pub fn deinit(self: *PageList) void {
 
     // Go through our linked list and deallocate all pages that are
     // heap-owned (not in the pool).
-    const page_alloc = self.pool.pages.arena.child_allocator;
+    const page_alloc = self.pool.pages.allocator;
     var it = self.pages.first;
     while (it) |node| : (it = node.next) {
         const page = node.restore(.discard);
@@ -945,7 +945,7 @@ pub fn reset(self: *PageList) void {
     // Before resetting our pools we need to free any pages that
     // are heap-owned since those were allocated outside the pool.
     {
-        const page_alloc = self.pool.pages.arena.child_allocator;
+        const page_alloc = self.pool.pages.allocator;
         var it = self.pages.first;
         while (it) |node| : (it = node.next) {
             const page = node.restore(.discard);
@@ -970,26 +970,47 @@ pub fn reset(self: *PageList) void {
     // Our page pool relies on mmap to zero our page memory. Since we're
     // retaining a certain amount of memory, it won't use mmap and won't
     // be zeroed. This block zeroes out all the memory in the pool arena.
-    {
-        // Note: we only have to do this for the page pool because the
-        // nodes are always fully overwritten on each allocation.
-        const page_arena = &self.pool.pages.arena;
-        var it = page_arena.state.buffer_list.first;
-        while (it) |node| : (it = node.next) {
-            // WARN: Since HeapAllocator's BufNode is not public API,
-            // we have to hardcode its layout here. We do a comptime assert
-            // on Zig version to verify we check it on every bump.
+    //
+    // Note: we only have to do this for the page pool because the nodes are
+    // always fully overwritten on each allocation.
+    inline for (.{
+        self.pool.pages.unmanaged.arena_state.used_list,
+        self.pool.pages.unmanaged.arena_state.free_list,
+    }) |first| {
+        var node_ = first;
+        while (node_) |node| : (node_ = node.next) {
+            // NOTE: Zig 0.16.0's arenas don't use the linked list types
+            // anymore, so we can just reference fields directly. The node
+            // type is still private though, so we have to parse out some
+            // of the internal methods to work with the buffer - namely
+            // Node.loadBuf and Node.Size.toInt. They are combined below.
+            //
+            // PS: My (vancluever's) reading of the code gives me the
+            // impression that we no longer need to offset the data by the
+            // header, because there's no linked list overhead anymore. But
+            // I'm sure we'll see pretty quick when I run the tests. :)
+            //
             const BufNode = struct {
-                data: usize,
-                node: std.SinglyLinkedList.Node,
-            };
-            const buf_node: *BufNode = @fieldParentPtr("node", node);
+                size: Size,
+                end_index: usize,
+                next: ?*@This(),
 
-            // The fully allocated buffer
-            const alloc_buf = @as([*]u8, @ptrCast(buf_node))[0..buf_node.data];
-            // The buffer minus our header
-            const data_buf = alloc_buf[@sizeOf(BufNode)..];
-            @memset(data_buf, 0);
+                const Size = packed struct(usize) {
+                    resizing: bool,
+                    _: @Int(.unsigned, @bitSizeOf(usize) - 1) = 0,
+
+                    fn toInt(s: Size) usize {
+                        var int = s;
+                        int.resizing = false;
+                        return @bitCast(int);
+                    }
+                };
+            };
+
+            const buf_node_ptr: *BufNode = @ptrCast(node);
+            const buf_node_size = @atomicLoad(BufNode.Size, &buf_node_ptr.size, .monotonic);
+            const buf = @as([*]u8, @ptrCast(node))[0..buf_node_size.toInt()][@sizeOf(BufNode)..];
+            @memset(buf, 0);
         }
     }
 
@@ -1088,7 +1109,7 @@ pub fn clone(
     // Our list of pages
     var page_list: List = .{};
     errdefer {
-        const page_alloc = pool.pages.arena.child_allocator;
+        const page_alloc = pool.pages.allocator;
         var page_it = page_list.first;
         while (page_it) |node| : (page_it = node.next) {
             switch (node.owned) {
@@ -1742,7 +1763,7 @@ const ReflowCursor = struct {
                             // head and wrap before handling it.
                             self.page_cell.* = .{
                                 .content_tag = .codepoint,
-                                .content = .{ .codepoint = 0 },
+                                .content = .{ .codepoint = .{ .data = 0 } },
                                 .wide = .spacer_head,
                             };
 
@@ -1762,7 +1783,7 @@ const ReflowCursor = struct {
                         // Edge case, when resizing to 1 column, wide
                         // characters are just destroyed and replaced
                         // with empty narrow cells.
-                        self.page_cell.content.codepoint = 0;
+                        self.page_cell.content.codepoint = .{ .data = 0 };
                         self.page_cell.wide = .narrow;
                         self.cursorForward();
 
@@ -1882,7 +1903,7 @@ const ReflowCursor = struct {
 
                 // Unsafe builds we throw away grapheme data!
                 self.page_cell.content_tag = .codepoint;
-                self.page_cell.content = .{ .codepoint = 0xFFFD };
+                self.page_cell.content = .{ .codepoint = .{ .data = 0xFFFD } };
             };
         }
 
@@ -3838,7 +3859,7 @@ inline fn createPageExt(
 
     const layout = Page.layout(opts.cap);
     const pooled = !opts.exact_size and layout.total_size <= std_size;
-    const page_alloc = pool.pages.arena.child_allocator;
+    const page_alloc = pool.pages.allocator;
 
     // It would be better to encode this into the Zig error handling
     // system but that is a big undertaking and we only have a few
@@ -3915,7 +3936,7 @@ const CompressionScratch = union(enum) {
             return .{ .pooled = memory };
         }
 
-        const page_alloc = pool.pages.arena.child_allocator;
+        const page_alloc = pool.pages.allocator;
         return .{ .allocated = try page_alloc.alignedAlloc(
             u8,
             .fromByteUnits(std.heap.page_size_min),
@@ -3937,7 +3958,7 @@ const CompressionScratch = union(enum) {
                 pool.pages.destroy(memory);
             },
             .allocated => |memory| {
-                const page_alloc = pool.pages.arena.child_allocator;
+                const page_alloc = pool.pages.allocator;
                 page_alloc.free(memory);
             },
         }
@@ -4337,7 +4358,7 @@ fn destroyNodeExt(
         },
 
         .heap => {
-            const page_alloc = pool.pages.arena.child_allocator;
+            const page_alloc = pool.pages.allocator;
             page_alloc.free(page.memory);
         },
     }
@@ -7563,7 +7584,7 @@ test "PageList preserved page keeps compressed storage" {
     try testing.expect(page_.dirty);
     try testing.expectEqual(
         @as(u21, 'X'),
-        page_.getRowAndCell(3, 2).cell.content.codepoint,
+        page_.getRowAndCell(3, 2).cell.content.codepoint.data,
     );
 
     // The node still owns the same compressed representation, and neither its
@@ -7736,7 +7757,7 @@ test "PageList lazily restores compressed history made active by resize" {
     _ = s.compress(.full);
     try testing.expect(first.isCompressed());
     const cell = s.getCell(.{ .active = .{} }).?;
-    try testing.expectEqual(@as(u21, 'X'), cell.cell.content.codepoint);
+    try testing.expectEqual(@as(u21, 'X'), cell.cell.content.codepoint.data);
     try testing.expect(!first.isCompressed());
     try testing.expectEqual(memory_ptr, first.page().memory.ptr);
     try testing.expectEqual(memory_len, first.page().memory.len);
@@ -7860,7 +7881,7 @@ test "PageList compression restores through page access" {
     const page_pin: Pin = .{ .node = node, .x = 3, .y = 2 };
     try testing.expectEqual(
         @as(u21, 'X'),
-        page_pin.rowAndCell().cell.content.codepoint,
+        page_pin.rowAndCell().cell.content.codepoint.data,
     );
     try testing.expect(!node.isCompressed());
     try testing.expectEqual(memory_ptr, node.page().memory.ptr);
@@ -7885,7 +7906,7 @@ test "PageList compression restores through page access" {
     try testing.expect(!node.isCompressed());
     try testing.expectEqual(
         @as(u21, 'X'),
-        cloned.pages.first.?.page().getRowAndCell(3, 2).cell.content.codepoint,
+        cloned.pages.first.?.page().getRowAndCell(3, 2).cell.content.codepoint.data,
     );
 }
 
@@ -9322,14 +9343,14 @@ test "PageList scroll clear" {
         const cell = s.getCell(.{ .active = .{ .x = 0, .y = 0 } }).?;
         cell.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
     {
         const cell = s.getCell(.{ .active = .{ .x = 0, .y = 1 } }).?;
         cell.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -10034,7 +10055,7 @@ test "PageList increaseCapacity to increase styles" {
                 const rac = page.getRowAndCell(x, y);
                 rac.cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = @intCast(x) },
+                    .content = .{ .codepoint = .{ .data = @intCast(x) } },
                 };
             }
         }
@@ -10059,7 +10080,7 @@ test "PageList increaseCapacity to increase styles" {
                 const rac = page.getRowAndCell(x, y);
                 try testing.expectEqual(
                     @as(u21, @intCast(x)),
-                    rac.cell.content.codepoint,
+                    rac.cell.content.codepoint.data,
                 );
             }
         }
@@ -10084,7 +10105,7 @@ test "PageList increaseCapacity to increase graphemes" {
                 const rac = page.getRowAndCell(x, y);
                 rac.cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = @intCast(x) },
+                    .content = .{ .codepoint = .{ .data = @intCast(x) } },
                 };
             }
         }
@@ -10103,7 +10124,7 @@ test "PageList increaseCapacity to increase graphemes" {
                 const rac = page.getRowAndCell(x, y);
                 try testing.expectEqual(
                     @as(u21, @intCast(x)),
-                    rac.cell.content.codepoint,
+                    rac.cell.content.codepoint.data,
                 );
             }
         }
@@ -10128,7 +10149,7 @@ test "PageList increaseCapacity to increase hyperlinks" {
                 const rac = page.getRowAndCell(x, y);
                 rac.cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = @intCast(x) },
+                    .content = .{ .codepoint = .{ .data = @intCast(x) } },
                 };
             }
         }
@@ -10147,7 +10168,7 @@ test "PageList increaseCapacity to increase hyperlinks" {
                 const rac = page.getRowAndCell(x, y);
                 try testing.expectEqual(
                     @as(u21, @intCast(x)),
-                    rac.cell.content.codepoint,
+                    rac.cell.content.codepoint.data,
                 );
             }
         }
@@ -10172,7 +10193,7 @@ test "PageList increaseCapacity to increase string_bytes" {
                 const rac = page.getRowAndCell(x, y);
                 rac.cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = @intCast(x) },
+                    .content = .{ .codepoint = .{ .data = @intCast(x) } },
                 };
             }
         }
@@ -10191,7 +10212,7 @@ test "PageList increaseCapacity to increase string_bytes" {
                 const rac = page.getRowAndCell(x, y);
                 try testing.expectEqual(
                     @as(u21, @intCast(x)),
-                    rac.cell.content.codepoint,
+                    rac.cell.content.codepoint.data,
                 );
             }
         }
@@ -10606,7 +10627,7 @@ test "PageList cellIterator" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -10656,7 +10677,7 @@ test "PageList cellIterator reverse" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -10973,7 +10994,7 @@ test "PageList highlightSemanticContent prompt" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
                 .semantic_content = .prompt,
             };
         }
@@ -10983,7 +11004,7 @@ test "PageList highlightSemanticContent prompt" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'B' },
+                .content = .{ .codepoint = .{ .data = 'B' } },
                 .semantic_content = .input,
             };
         }
@@ -11027,7 +11048,7 @@ test "PageList highlightSemanticContent prompt with output" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11037,7 +11058,7 @@ test "PageList highlightSemanticContent prompt with output" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'l' },
+                .content = .{ .codepoint = .{ .data = 'l' } },
                 .semantic_content = .input,
             };
         }
@@ -11047,7 +11068,7 @@ test "PageList highlightSemanticContent prompt with output" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11092,7 +11113,7 @@ test "PageList highlightSemanticContent prompt multiline" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11103,7 +11124,7 @@ test "PageList highlightSemanticContent prompt multiline" {
             const cell = page.getRowAndCell(x, 6).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'c' },
+                .content = .{ .codepoint = .{ .data = 'c' } },
                 .semantic_content = .input,
             };
         }
@@ -11147,7 +11168,7 @@ test "PageList highlightSemanticContent prompt only" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11191,7 +11212,7 @@ test "PageList highlightSemanticContent prompt to end of screen" {
             const cell = page.getRowAndCell(x, 15).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11200,7 +11221,7 @@ test "PageList highlightSemanticContent prompt to end of screen" {
             const cell = page.getRowAndCell(x, 15).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'c' },
+                .content = .{ .codepoint = .{ .data = 'c' } },
                 .semantic_content = .input,
             };
         }
@@ -11240,7 +11261,7 @@ test "PageList highlightSemanticContent input basic" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11250,7 +11271,7 @@ test "PageList highlightSemanticContent input basic" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'l' },
+                .content = .{ .codepoint = .{ .data = 'l' } },
                 .semantic_content = .input,
             };
         }
@@ -11295,7 +11316,7 @@ test "PageList highlightSemanticContent input with output" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11305,7 +11326,7 @@ test "PageList highlightSemanticContent input with output" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'c' },
+                .content = .{ .codepoint = .{ .data = 'c' } },
                 .semantic_content = .input,
             };
         }
@@ -11315,7 +11336,7 @@ test "PageList highlightSemanticContent input with output" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11360,7 +11381,7 @@ test "PageList highlightSemanticContent input multiline with continuation" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11370,7 +11391,7 @@ test "PageList highlightSemanticContent input multiline with continuation" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'c' },
+                .content = .{ .codepoint = .{ .data = 'c' } },
                 .semantic_content = .input,
             };
         }
@@ -11382,7 +11403,7 @@ test "PageList highlightSemanticContent input multiline with continuation" {
             const cell = page.getRowAndCell(x, 6).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '>' },
+                .content = .{ .codepoint = .{ .data = '>' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11392,7 +11413,7 @@ test "PageList highlightSemanticContent input multiline with continuation" {
             const cell = page.getRowAndCell(x, 6).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'd' },
+                .content = .{ .codepoint = .{ .data = 'd' } },
                 .semantic_content = .input,
             };
         }
@@ -11437,7 +11458,7 @@ test "PageList highlightSemanticContent input no input returns null" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11447,7 +11468,7 @@ test "PageList highlightSemanticContent input no input returns null" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11484,7 +11505,7 @@ test "PageList highlightSemanticContent input to end of screen" {
             const cell = page.getRowAndCell(x, 15).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11493,7 +11514,7 @@ test "PageList highlightSemanticContent input to end of screen" {
             const cell = page.getRowAndCell(x, 15).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'c' },
+                .content = .{ .codepoint = .{ .data = 'c' } },
                 .semantic_content = .input,
             };
         }
@@ -11533,7 +11554,7 @@ test "PageList highlightSemanticContent input prompt only returns null" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11580,7 +11601,7 @@ test "PageList highlightSemanticContent output basic" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11590,7 +11611,7 @@ test "PageList highlightSemanticContent output basic" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'l' },
+                .content = .{ .codepoint = .{ .data = 'l' } },
                 .semantic_content = .input,
             };
         }
@@ -11600,7 +11621,7 @@ test "PageList highlightSemanticContent output basic" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11651,7 +11672,7 @@ test "PageList highlightSemanticContent output multiline" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11661,7 +11682,7 @@ test "PageList highlightSemanticContent output multiline" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'l' },
+                .content = .{ .codepoint = .{ .data = 'l' } },
                 .semantic_content = .input,
             };
         }
@@ -11671,7 +11692,7 @@ test "PageList highlightSemanticContent output multiline" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11682,7 +11703,7 @@ test "PageList highlightSemanticContent output multiline" {
             const cell = page.getRowAndCell(x, 6).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11693,7 +11714,7 @@ test "PageList highlightSemanticContent output multiline" {
             const cell = page.getRowAndCell(x, 7).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11742,7 +11763,7 @@ test "PageList highlightSemanticContent output stops at next prompt" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11752,7 +11773,7 @@ test "PageList highlightSemanticContent output stops at next prompt" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'l' },
+                .content = .{ .codepoint = .{ .data = 'l' } },
                 .semantic_content = .input,
             };
         }
@@ -11762,7 +11783,7 @@ test "PageList highlightSemanticContent output stops at next prompt" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11773,7 +11794,7 @@ test "PageList highlightSemanticContent output stops at next prompt" {
             const cell = page.getRowAndCell(x, 6).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11782,7 +11803,7 @@ test "PageList highlightSemanticContent output stops at next prompt" {
             const cell = page.getRowAndCell(x, 6).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11826,7 +11847,7 @@ test "PageList highlightSemanticContent output to end of screen" {
             const cell = page.getRowAndCell(x, 15).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11835,7 +11856,7 @@ test "PageList highlightSemanticContent output to end of screen" {
             const cell = page.getRowAndCell(x, 15).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'c' },
+                .content = .{ .codepoint = .{ .data = 'c' } },
                 .semantic_content = .input,
             };
         }
@@ -11844,7 +11865,7 @@ test "PageList highlightSemanticContent output to end of screen" {
             const cell = page.getRowAndCell(x, 15).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11855,7 +11876,7 @@ test "PageList highlightSemanticContent output to end of screen" {
             const cell = page.getRowAndCell(x, 16).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'o' },
+                .content = .{ .codepoint = .{ .data = 'o' } },
                 .semantic_content = .output,
             };
         }
@@ -11899,7 +11920,7 @@ test "PageList highlightSemanticContent output no output returns null" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11909,7 +11930,7 @@ test "PageList highlightSemanticContent output no output returns null" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'c' },
+                .content = .{ .codepoint = .{ .data = 'c' } },
                 .semantic_content = .input,
             };
         }
@@ -11959,7 +11980,7 @@ test "PageList highlightSemanticContent output skips empty cells" {
             const cell = page.getRowAndCell(x, 5).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '$' },
+                .content = .{ .codepoint = .{ .data = '$' } },
                 .semantic_content = .prompt,
             };
         }
@@ -11973,7 +11994,7 @@ test "PageList highlightSemanticContent output skips empty cells" {
             const cell = page.getRowAndCell(x, 6).cell;
             cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'l' },
+                .content = .{ .codepoint = .{ .data = 'l' } },
                 .semantic_content = .input,
             };
         }
@@ -11987,7 +12008,7 @@ test "PageList highlightSemanticContent output skips empty cells" {
                 const cell = page.getRowAndCell(x, y).cell;
                 cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = 'o' },
+                    .content = .{ .codepoint = .{ .data = 'o' } },
                     .semantic_content = .output,
                 };
             }
@@ -12268,7 +12289,7 @@ test "PageList erase a one-row active" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -12278,7 +12299,7 @@ test "PageList erase a one-row active" {
     // The row should be empty
     {
         const get = s.getCell(.{ .active = .{ .x = 0, .y = 0 } }).?;
-        try testing.expectEqual(@as(u21, 0), get.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), get.cell.content.codepoint.data);
     }
 }
 
@@ -12490,7 +12511,7 @@ test "PageList eraseRow hyperlink-dense row crosses page boundary" {
         const row_pin = s.pin(.{ .active = .{ .y = @intCast(y) } }).?;
         row_pin.rowAndCell().cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast('0' + y) },
+            .content = .{ .codepoint = .{ .data = @intCast('0' + y) } },
         };
     }
 
@@ -12516,7 +12537,7 @@ test "PageList eraseRow hyperlink-dense row crosses page boundary" {
             const rac = page.getRowAndCell(x, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast('A' + x) },
+                .content = .{ .codepoint = .{ .data = @intCast('A' + x) } },
             };
             try page.setHyperlink(rac.row, rac.cell, id);
             page.hyperlink_set.use(page.memory, id);
@@ -12539,7 +12560,7 @@ test "PageList eraseRow hyperlink-dense row crosses page boundary" {
     const expected = [10]u21{ '1', '2', '3', '4', 'A', '6', '7', '8', '9', 0 };
     for (expected, 0..) |cp, y| {
         const list_cell = s.getCell(.{ .active = .{ .y = @intCast(y) } }).?;
-        try testing.expectEqual(cp, list_cell.cell.content.codepoint);
+        try testing.expectEqual(cp, list_cell.cell.content.codepoint.data);
     }
 
     // Every cell of the dense row must still resolve to a real
@@ -12602,7 +12623,7 @@ test "PageList eraseRowBounded hyperlink-dense row crosses page boundary" {
         const row_pin = s.pin(.{ .active = .{ .y = @intCast(y) } }).?;
         row_pin.rowAndCell().cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast('0' + y) },
+            .content = .{ .codepoint = .{ .data = @intCast('0' + y) } },
         };
     }
 
@@ -12628,7 +12649,7 @@ test "PageList eraseRowBounded hyperlink-dense row crosses page boundary" {
             const rac = page.getRowAndCell(x, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast('A' + x) },
+                .content = .{ .codepoint = .{ .data = @intCast('A' + x) } },
             };
             try page.setHyperlink(rac.row, rac.cell, id);
             page.hyperlink_set.use(page.memory, id);
@@ -12648,7 +12669,7 @@ test "PageList eraseRowBounded hyperlink-dense row crosses page boundary" {
     const expected = [10]u21{ '1', '2', '3', '4', 'A', '6', 0, '7', '8', '9' };
     for (expected, 0..) |cp, y| {
         const list_cell = s.getCell(.{ .active = .{ .y = @intCast(y) } }).?;
-        try testing.expectEqual(cp, list_cell.cell.content.codepoint);
+        try testing.expectEqual(cp, list_cell.cell.content.codepoint.data);
     }
 
     // Every cell of the dense row must still resolve to a real
@@ -12745,7 +12766,7 @@ test "PageList clone partial trimmed left reclaims styles" {
             rac.row.styled = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
                 .style_id = style_id,
             };
             page.styles.use(page.memory, style_id);
@@ -12971,7 +12992,7 @@ test "PageList resize (no reflow) less rows" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -13005,7 +13026,7 @@ test "PageList resize (no reflow) one rows" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -13039,7 +13060,7 @@ test "PageList resize (no reflow) less rows cursor on bottom" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -13052,7 +13073,7 @@ test "PageList resize (no reflow) less rows cursor on bottom" {
             .x = cursor.x,
             .y = cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, 9), get.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 9), get.cell.content.codepoint.data);
     }
 
     // Resize
@@ -13091,7 +13112,7 @@ test "PageList resize (no reflow) less rows cursor in scrollback" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -13104,7 +13125,7 @@ test "PageList resize (no reflow) less rows cursor in scrollback" {
             .x = cursor.x,
             .y = cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, 2), get.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 2), get.cell.content.codepoint.data);
     }
 
     // Resize
@@ -13142,7 +13163,7 @@ test "PageList resize (no reflow) less rows trims blank lines" {
         const rac = page.getRowAndCell(0, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -13164,7 +13185,7 @@ test "PageList resize (no reflow) less rows trims blank lines" {
             .x = cursor.x,
             .y = cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, 'A'), get.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), get.cell.content.codepoint.data);
     }
 
     // Resize
@@ -13201,7 +13222,7 @@ test "PageList resize (no reflow) less rows trims blank lines cursor in blank li
         const rac = page.getRowAndCell(0, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -13251,7 +13272,7 @@ test "PageList resize (no reflow) less rows trims blank lines erases pages" {
         const rac = page.getRowAndCell(0, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -13277,7 +13298,7 @@ test "PageList resize (no reflow) more rows extends blank lines" {
         const rac = page.getRowAndCell(0, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
 
@@ -13397,7 +13418,7 @@ test "PageList resize (no reflow) less cols clears graphemes" {
         const rac = page.getRowAndCell(9, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
         try page.appendGrapheme(rac.row, rac.cell, 'A');
     }
@@ -13449,14 +13470,14 @@ test "PageList resize (no reflow) more cols with spacer head" {
             rac.row.wrap = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_head,
             };
         }
@@ -13464,7 +13485,7 @@ test "PageList resize (no reflow) more cols with spacer head" {
             const rac = page.getRowAndCell(0, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '😀' },
+                .content = .{ .codepoint = .{ .data = '😀' } },
                 .wide = .wide,
             };
         }
@@ -13472,7 +13493,7 @@ test "PageList resize (no reflow) more cols with spacer head" {
             const rac = page.getRowAndCell(1, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -13489,18 +13510,18 @@ test "PageList resize (no reflow) more cols with spacer head" {
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
             // try testing.expect(!rac.row.wrap);
         }
         {
             const rac = page.getRowAndCell(1, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(2, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
     }
@@ -13532,14 +13553,14 @@ test "PageList resize (no reflow) grow cols fast path with spacer head" {
             const rac = page.getRowAndCell(0, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(4, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_head,
             };
             rac.row.wrap = true;
@@ -13550,7 +13571,7 @@ test "PageList resize (no reflow) grow cols fast path with spacer head" {
             const rac = page.getRowAndCell(4, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_head,
             };
             rac.row.wrap = true;
@@ -13747,7 +13768,7 @@ test "PageList resize less rows and cols cursor near top pushed to scrollback" {
             const cells = p.node.page().getCells(rac.row);
             for (cells, 0..) |*cell, x| cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast('A' + (x % 26)) },
+                .content = .{ .codepoint = .{ .data = @intCast('A' + (x % 26)) } },
             };
         }
     }
@@ -13863,7 +13884,7 @@ test "PageList resize (no reflow) more cols forces smaller cap" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
             };
         }
     }
@@ -13879,7 +13900,7 @@ test "PageList resize (no reflow) more cols forces smaller cap" {
         const rac = offset.rowAndCell();
         const cells = offset.node.page().getCells(rac.row);
         try testing.expectEqual(@as(usize, cap2.cols), cells.len);
-        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint.data);
     }
 }
 
@@ -13898,7 +13919,7 @@ test "PageList resize (no reflow) more rows adds blank rows if cursor at bottom"
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -13920,7 +13941,7 @@ test "PageList resize (no reflow) more rows adds blank rows if cursor at bottom"
             .x = original_cursor.x,
             .y = original_cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, 3), get.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 3), get.cell.content.codepoint.data);
     }
 
     // Resize
@@ -13952,7 +13973,7 @@ test "PageList resize (no reflow) more rows adds blank rows if cursor at bottom"
     for (0..3) |y| {
         const get = s.getCell(.{ .active = .{ .y = @intCast(y) } }).?;
         const expected: u21 = @intCast(y + 2);
-        try testing.expectEqual(expected, get.cell.content.codepoint);
+        try testing.expectEqual(expected, get.cell.content.codepoint.data);
     }
 }
 
@@ -13969,7 +13990,7 @@ test "PageList resize reflow more cols no wrapped rows" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
             };
         }
     }
@@ -13984,7 +14005,7 @@ test "PageList resize reflow more cols no wrapped rows" {
         const rac = offset.rowAndCell();
         const cells = offset.node.page().getCells(rac.row);
         try testing.expectEqual(@as(usize, 10), cells.len);
-        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint.data);
     }
 }
 
@@ -14009,7 +14030,7 @@ test "PageList resize reflow more cols wrapped rows" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
             };
         }
     }
@@ -14036,8 +14057,8 @@ test "PageList resize reflow more cols wrapped rows" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(!rac.row.wrap);
         try testing.expectEqual(@as(usize, 4), cells.len);
-        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint);
-        try testing.expectEqual(@as(u21, 'A'), cells[2].content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 'A'), cells[2].content.codepoint.data);
     }
 }
 
@@ -14063,7 +14084,7 @@ test "PageList resize reflow invalidates viewport offset cache" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
             };
         }
     }
@@ -14124,7 +14145,7 @@ test "PageList resize reflow more cols creates multiple pages" {
             const rac = page.getRowAndCell(0, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
             };
         }
     }
@@ -14188,7 +14209,7 @@ test "PageList resize reflow more cols wrap across page boundary" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14203,7 +14224,7 @@ test "PageList resize reflow more cols wrap across page boundary" {
             const rac = page2.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14278,10 +14299,10 @@ test "PageList resize reflow more cols wrap across page boundary" {
         try testing.expect(!row.wrap_continuation);
 
         const cells = p.cells(.all);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
-        try testing.expectEqual(@as(u21, 1), cells[1].content.codepoint);
-        try testing.expectEqual(@as(u21, 0), cells[2].content.codepoint);
-        try testing.expectEqual(@as(u21, 1), cells[3].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 1), cells[1].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 0), cells[2].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 1), cells[3].content.codepoint.data);
     }
 }
 
@@ -14319,7 +14340,7 @@ test "PageList resize reflow more cols wrap across page boundary cursor in secon
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14334,7 +14355,7 @@ test "PageList resize reflow more cols wrap across page boundary cursor in secon
             const rac = page2.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14364,10 +14385,10 @@ test "PageList resize reflow more cols wrap across page boundary cursor in secon
         try testing.expect(!row.wrap);
 
         const cells = p2.cells(.all);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
-        try testing.expectEqual(@as(u21, 1), cells[1].content.codepoint);
-        try testing.expectEqual(@as(u21, 0), cells[2].content.codepoint);
-        try testing.expectEqual(@as(u21, 1), cells[3].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 1), cells[1].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 0), cells[2].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 1), cells[3].content.codepoint.data);
     }
 }
 
@@ -14405,7 +14426,7 @@ test "PageList resize reflow less cols wrap across page boundary cursor in secon
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14420,7 +14441,7 @@ test "PageList resize reflow less cols wrap across page boundary cursor in secon
             const rac = page2.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14506,10 +14527,10 @@ test "PageList resize reflow less cols wrap across page boundary cursor in secon
         try testing.expect(!row.wrap_continuation);
 
         const cells = p2.cells(.all);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
-        try testing.expectEqual(@as(u21, 1), cells[1].content.codepoint);
-        try testing.expectEqual(@as(u21, 2), cells[2].content.codepoint);
-        try testing.expectEqual(@as(u21, 3), cells[3].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 1), cells[1].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 2), cells[2].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 3), cells[3].content.codepoint.data);
     }
     {
         // PAGE 0 ROW 7897, ACTIVE 5
@@ -14519,10 +14540,10 @@ test "PageList resize reflow less cols wrap across page boundary cursor in secon
         try testing.expect(row.wrap_continuation);
 
         const cells = p2.cells(.all);
-        try testing.expectEqual(@as(u21, 4), cells[0].content.codepoint);
-        try testing.expectEqual(@as(u21, 0), cells[1].content.codepoint);
-        try testing.expectEqual(@as(u21, 1), cells[2].content.codepoint);
-        try testing.expectEqual(@as(u21, 2), cells[3].content.codepoint);
+        try testing.expectEqual(@as(u21, 4), cells[0].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 0), cells[1].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 1), cells[2].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 2), cells[3].content.codepoint.data);
     }
     {
         // PAGE 0 ROW 7898, ACTIVE 6
@@ -14532,8 +14553,8 @@ test "PageList resize reflow less cols wrap across page boundary cursor in secon
         try testing.expect(row.wrap_continuation);
 
         const cells = p2.cells(.all);
-        try testing.expectEqual(@as(u21, 3), cells[0].content.codepoint);
-        try testing.expectEqual(@as(u21, 4), cells[1].content.codepoint);
+        try testing.expectEqual(@as(u21, 3), cells[0].content.codepoint.data);
+        try testing.expectEqual(@as(u21, 4), cells[1].content.codepoint.data);
     }
     {
         // PAGE 0 ROW 7899, ACTIVE 7
@@ -14567,7 +14588,7 @@ test "PageList resize reflow more cols cursor in wrapped row" {
             const rac = page.getRowAndCell(x, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14580,7 +14601,7 @@ test "PageList resize reflow more cols cursor in wrapped row" {
             const rac = page.getRowAndCell(x, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14618,7 +14639,7 @@ test "PageList resize reflow more cols cursor in not wrapped row" {
             const rac = page.getRowAndCell(x, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14631,7 +14652,7 @@ test "PageList resize reflow more cols cursor in not wrapped row" {
             const rac = page.getRowAndCell(x, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14669,7 +14690,7 @@ test "PageList resize reflow more cols cursor in wrapped row that isn't unwrappe
             const rac = page.getRowAndCell(x, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14683,7 +14704,7 @@ test "PageList resize reflow more cols cursor in wrapped row that isn't unwrappe
             const rac = page.getRowAndCell(x, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14696,7 +14717,7 @@ test "PageList resize reflow more cols cursor in wrapped row that isn't unwrappe
             const rac = page.getRowAndCell(x, 2);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -14797,7 +14818,7 @@ test "PageList resize reflow exceeds hyperlink memory forcing capacity increase"
         rac.row.wrap = true;
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'X' },
+            .content = .{ .codepoint = .{ .data = 'X' } },
         };
         try page.setHyperlink(rac.row, rac.cell, id);
         try std.testing.expectError(
@@ -14821,7 +14842,7 @@ test "PageList resize reflow exceeds hyperlink memory forcing capacity increase"
         rac.row.wrap_continuation = true;
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'X' },
+            .content = .{ .codepoint = .{ .data = 'X' } },
         };
         try page.setHyperlink(rac.row, rac.cell, id);
         try std.testing.expectError(
@@ -14887,7 +14908,7 @@ test "PageList resize reflow exceeds grapheme memory forcing capacity increase"
         rac.row.wrap = true;
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'X' },
+            .content = .{ .codepoint = .{ .data = 'X' } },
         };
         try page.setGraphemes(
             rac.row,
@@ -14920,7 +14941,7 @@ test "PageList resize reflow exceeds grapheme memory forcing capacity increase"
         rac.row.wrap = true;
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'X' },
+            .content = .{ .codepoint = .{ .data = 'X' } },
         };
         try page.setGraphemes(
             rac.row,
@@ -14996,7 +15017,7 @@ test "PageList resize reflow exceeds style memory forcing capacity increase" {
             rac.row.styled = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'X' },
+                .content = .{ .codepoint = .{ .data = 'X' } },
                 .style_id = id,
             };
         }
@@ -15023,7 +15044,7 @@ test "PageList resize reflow exceeds style memory forcing capacity increase" {
             rac.row.styled = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'X' },
+                .content = .{ .codepoint = .{ .data = 'X' } },
                 .style_id = id,
             };
         }
@@ -15048,14 +15069,14 @@ test "PageList resize reflow more cols unwrap wide spacer head" {
             rac.row.wrap = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_head,
             };
         }
@@ -15064,7 +15085,7 @@ test "PageList resize reflow more cols unwrap wide spacer head" {
             rac.row.wrap_continuation = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '😀' },
+                .content = .{ .codepoint = .{ .data = '😀' } },
                 .wide = .wide,
             };
         }
@@ -15072,7 +15093,7 @@ test "PageList resize reflow more cols unwrap wide spacer head" {
             const rac = page.getRowAndCell(1, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -15089,18 +15110,18 @@ test "PageList resize reflow more cols unwrap wide spacer head" {
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
             try testing.expect(!rac.row.wrap);
         }
         {
             const rac = page.getRowAndCell(1, 0);
-            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.wide, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(2, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_tail, rac.cell.wide);
         }
     }
@@ -15121,14 +15142,14 @@ test "PageList resize reflow more cols unwrap wide spacer head across two rows"
             rac.row.wrap = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
@@ -15137,14 +15158,14 @@ test "PageList resize reflow more cols unwrap wide spacer head across two rows"
             rac.row.wrap = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(1, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_head,
             };
         }
@@ -15153,7 +15174,7 @@ test "PageList resize reflow more cols unwrap wide spacer head across two rows"
             rac.row.wrap_continuation = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '😀' },
+                .content = .{ .codepoint = .{ .data = '😀' } },
                 .wide = .wide,
             };
         }
@@ -15161,7 +15182,7 @@ test "PageList resize reflow more cols unwrap wide spacer head across two rows"
             const rac = page.getRowAndCell(1, 2);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -15178,33 +15199,33 @@ test "PageList resize reflow more cols unwrap wide spacer head across two rows"
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
             try testing.expect(rac.row.wrap);
         }
         {
             const rac = page.getRowAndCell(1, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(2, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(3, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_head, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(0, 1);
-            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.wide, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(1, 1);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_tail, rac.cell.wide);
         }
     }
@@ -15225,14 +15246,14 @@ test "PageList resize reflow more cols unwrap still requires wide spacer head" {
             rac.row.wrap = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
@@ -15240,7 +15261,7 @@ test "PageList resize reflow more cols unwrap still requires wide spacer head" {
             rac.row.wrap_continuation = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '😀' },
+                .content = .{ .codepoint = .{ .data = '😀' } },
                 .wide = .wide,
             };
         }
@@ -15248,7 +15269,7 @@ test "PageList resize reflow more cols unwrap still requires wide spacer head" {
             const rac = page.getRowAndCell(1, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -15265,28 +15286,28 @@ test "PageList resize reflow more cols unwrap still requires wide spacer head" {
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
             try testing.expect(rac.row.wrap);
         }
         {
             const rac = page.getRowAndCell(1, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(2, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_head, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(0, 1);
-            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.wide, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(1, 1);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_tail, rac.cell.wide);
         }
     }
@@ -15308,7 +15329,7 @@ test "PageList resize reflow less cols no reflow preserves semantic prompt" {
             const rac = page.getRowAndCell(x, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15401,7 +15422,7 @@ test "PageList resize reflow less cols no wrapped rows" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15419,7 +15440,7 @@ test "PageList resize reflow less cols no wrapped rows" {
             const rac = offset_copy.rowAndCell();
             const cells = offset.node.page().getCells(rac.row);
             try testing.expectEqual(@as(usize, 5), cells.len);
-            try testing.expectEqual(@as(u21, @intCast(x)), cells[x].content.codepoint);
+            try testing.expectEqual(@as(u21, @intCast(x)), cells[x].content.codepoint.data);
         }
     }
 }
@@ -15437,7 +15458,7 @@ test "PageList resize reflow less cols wrapped rows" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15464,7 +15485,7 @@ test "PageList resize reflow less cols wrapped rows" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
@@ -15472,7 +15493,7 @@ test "PageList resize reflow less cols wrapped rows" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(!rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint.data);
     }
     {
         // First row should be wrapped
@@ -15481,7 +15502,7 @@ test "PageList resize reflow less cols wrapped rows" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
@@ -15489,7 +15510,7 @@ test "PageList resize reflow less cols wrapped rows" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(!rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint.data);
     }
 }
 
@@ -15507,7 +15528,7 @@ test "PageList resize reflow less cols wrapped rows with graphemes" {
                 const rac = page.getRowAndCell(x, y);
                 rac.cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = @intCast(x) },
+                    .content = .{ .codepoint = .{ .data = @intCast(x) } },
                 };
             }
 
@@ -15540,7 +15561,7 @@ test "PageList resize reflow less cols wrapped rows with graphemes" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
@@ -15549,7 +15570,7 @@ test "PageList resize reflow less cols wrapped rows with graphemes" {
         try testing.expect(!rac.row.wrap);
         try testing.expect(rac.row.grapheme);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint.data);
 
         const cps = page.lookupGrapheme(rac.cell).?;
         try testing.expectEqual(@as(usize, 1), cps.len);
@@ -15562,7 +15583,7 @@ test "PageList resize reflow less cols wrapped rows with graphemes" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
@@ -15571,7 +15592,7 @@ test "PageList resize reflow less cols wrapped rows with graphemes" {
         try testing.expect(!rac.row.wrap);
         try testing.expect(rac.row.grapheme);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint.data);
 
         const cps = page.lookupGrapheme(rac.cell).?;
         try testing.expectEqual(@as(usize, 1), cps.len);
@@ -15592,7 +15613,7 @@ test "PageList resize reflow less cols cursor in wrapped row" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15628,28 +15649,28 @@ test "PageList resize reflow less cols wraps spacer head" {
             rac.row.wrap = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(2, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(3, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_head,
             };
         }
@@ -15658,7 +15679,7 @@ test "PageList resize reflow less cols wraps spacer head" {
             rac.row.wrap_continuation = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '😀' },
+                .content = .{ .codepoint = .{ .data = '😀' } },
                 .wide = .wide,
             };
         }
@@ -15666,7 +15687,7 @@ test "PageList resize reflow less cols wraps spacer head" {
             const rac = page.getRowAndCell(1, 1);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -15683,28 +15704,28 @@ test "PageList resize reflow less cols wraps spacer head" {
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
             try testing.expect(rac.row.wrap);
         }
         {
             const rac = page.getRowAndCell(1, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(2, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(0, 1);
-            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.wide, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(1, 1);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_tail, rac.cell.wide);
         }
     }
@@ -15722,7 +15743,7 @@ test "PageList resize reflow less cols cursor goes to scrollback" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15753,7 +15774,7 @@ test "PageList resize reflow less cols cursor in unchanged row" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15787,7 +15808,7 @@ test "PageList resize reflow less cols cursor in blank cell" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15821,7 +15842,7 @@ test "PageList resize reflow less cols cursor in final blank cell" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15855,7 +15876,7 @@ test "PageList resize reflow less cols cursor in wrapped blank cell" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15889,7 +15910,7 @@ test "PageList resize reflow less cols blank lines" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15907,7 +15928,7 @@ test "PageList resize reflow less cols blank lines" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
@@ -15915,7 +15936,7 @@ test "PageList resize reflow less cols blank lines" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(!rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint.data);
     }
 }
 
@@ -15932,7 +15953,7 @@ test "PageList resize reflow less cols blank lines between" {
             const rac = page.getRowAndCell(x, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15941,7 +15962,7 @@ test "PageList resize reflow less cols blank lines between" {
             const rac = page.getRowAndCell(x, 2);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -15963,7 +15984,7 @@ test "PageList resize reflow less cols blank lines between" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
@@ -15971,7 +15992,7 @@ test "PageList resize reflow less cols blank lines between" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(!rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 2), cells[0].content.codepoint.data);
     }
 }
 
@@ -15987,14 +16008,14 @@ test "PageList resize reflow less cols blank lines between no scrollback" {
         const rac = page.getRowAndCell(0, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'A' },
+            .content = .{ .codepoint = .{ .data = 'A' } },
         };
     }
     {
         const rac = page.getRowAndCell(0, 2);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'C' },
+            .content = .{ .codepoint = .{ .data = 'C' } },
         };
     }
 
@@ -16010,13 +16031,13 @@ test "PageList resize reflow less cols blank lines between no scrollback" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(!rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
         const rac = offset.rowAndCell();
         const cells = offset.node.page().getCells(rac.row);
-        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cells[0].content.codepoint.data);
     }
     {
         const offset = it.next().?;
@@ -16024,7 +16045,7 @@ test "PageList resize reflow less cols blank lines between no scrollback" {
         const cells = offset.node.page().getCells(rac.row);
         try testing.expect(!rac.row.wrap);
         try testing.expectEqual(@as(usize, 2), cells.len);
-        try testing.expectEqual(@as(u21, 'C'), cells[0].content.codepoint);
+        try testing.expectEqual(@as(u21, 'C'), cells[0].content.codepoint.data);
     }
 }
 
@@ -16041,7 +16062,7 @@ test "PageList resize reflow less cols cursor not on last line preserves locatio
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
             };
         }
     }
@@ -16090,7 +16111,7 @@ test "PageList resize reflow less cols copy style" {
             const rac = page.getRowAndCell(x, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x) },
+                .content = .{ .codepoint = .{ .data = @intCast(x) } },
                 .style_id = style_id,
             };
             page.styles.use(page.memory, style_id);
@@ -16140,7 +16161,7 @@ test "PageList resize reflow less cols to eliminate a wide char" {
             const rac = page.getRowAndCell(0, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '😀' },
+                .content = .{ .codepoint = .{ .data = '😀' } },
                 .wide = .wide,
             };
         }
@@ -16148,7 +16169,7 @@ test "PageList resize reflow less cols to eliminate a wide char" {
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -16165,7 +16186,7 @@ test "PageList resize reflow less cols to eliminate a wide char" {
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
         }
     }
@@ -16185,14 +16206,14 @@ test "PageList resize reflow less cols to wrap a wide char" {
             const rac = page.getRowAndCell(0, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'x' },
+                .content = .{ .codepoint = .{ .data = 'x' } },
             };
         }
         {
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = '😀' },
+                .content = .{ .codepoint = .{ .data = '😀' } },
                 .wide = .wide,
             };
         }
@@ -16200,7 +16221,7 @@ test "PageList resize reflow less cols to wrap a wide char" {
             const rac = page.getRowAndCell(2, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -16217,23 +16238,23 @@ test "PageList resize reflow less cols to wrap a wide char" {
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 'x'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.narrow, rac.cell.wide);
             try testing.expect(rac.row.wrap);
         }
         {
             const rac = page.getRowAndCell(1, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_head, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(0, 1);
-            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, '😀'), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.wide, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(1, 1);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_tail, rac.cell.wide);
         }
     }
@@ -16258,7 +16279,7 @@ test "PageList resize reflow less cols to wrap a multi-codepoint grapheme with a
             const rac = page.getRowAndCell(0, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0x1F468 }, // First codepoint of the grapheme
+                .content = .{ .codepoint = .{ .data = 0x1F468 } }, // First codepoint of the grapheme
                 .wide = .wide,
             };
             try page.setGraphemes(rac.row, rac.cell, &.{
@@ -16271,7 +16292,7 @@ test "PageList resize reflow less cols to wrap a multi-codepoint grapheme with a
             const rac = page.getRowAndCell(1, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -16280,7 +16301,7 @@ test "PageList resize reflow less cols to wrap a multi-codepoint grapheme with a
             const rac = page.getRowAndCell(2, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0x1F468 }, // First codepoint of the grapheme
+                .content = .{ .codepoint = .{ .data = 0x1F468 } }, // First codepoint of the grapheme
                 .wide = .wide,
             };
             try page.setGraphemes(rac.row, rac.cell, &.{
@@ -16293,7 +16314,7 @@ test "PageList resize reflow less cols to wrap a multi-codepoint grapheme with a
             const rac = page.getRowAndCell(3, 0);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0 },
+                .content = .{ .codepoint = .{ .data = 0 } },
                 .wide = .spacer_tail,
             };
         }
@@ -16310,7 +16331,7 @@ test "PageList resize reflow less cols to wrap a multi-codepoint grapheme with a
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 0x1F468), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0x1F468), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.wide, rac.cell.wide);
 
             const cps = page.lookupGrapheme(rac.cell).?;
@@ -16327,18 +16348,18 @@ test "PageList resize reflow less cols to wrap a multi-codepoint grapheme with a
         }
         {
             const rac = page.getRowAndCell(1, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_tail, rac.cell.wide);
         }
         {
             const rac = page.getRowAndCell(2, 0);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_head, rac.cell.wide);
         }
 
         {
             const rac = page.getRowAndCell(0, 0);
-            try testing.expectEqual(@as(u21, 0x1F468), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0x1F468), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.wide, rac.cell.wide);
 
             const cps = page.lookupGrapheme(rac.cell).?;
@@ -16352,7 +16373,7 @@ test "PageList resize reflow less cols to wrap a multi-codepoint grapheme with a
         }
         {
             const rac = page.getRowAndCell(1, 1);
-            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+            try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
             try testing.expectEqual(pagepkg.Cell.Wide.spacer_tail, rac.cell.wide);
         }
     }
@@ -16376,7 +16397,7 @@ test "PageList resize reflow less cols copy kitty placeholder" {
             rac.row.kitty_virtual_placeholder = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = kitty.graphics.unicode.placeholder },
+                .content = .{ .codepoint = .{ .data = kitty.graphics.unicode.placeholder } },
             };
         }
     }
@@ -16417,7 +16438,7 @@ test "PageList resize reflow more cols clears kitty placeholder" {
             rac.row.kitty_virtual_placeholder = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = kitty.graphics.unicode.placeholder },
+                .content = .{ .codepoint = .{ .data = kitty.graphics.unicode.placeholder } },
             };
         }
     }
@@ -16460,7 +16481,7 @@ test "PageList resize reflow wrap moves kitty placeholder" {
             rac.row.kitty_virtual_placeholder = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = kitty.graphics.unicode.placeholder },
+                .content = .{ .codepoint = .{ .data = kitty.graphics.unicode.placeholder } },
             };
         }
     }
@@ -16669,7 +16690,7 @@ test "PageList resize reflow grapheme map capacity exceeded" {
             const rac = page.getRowAndCell(0, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'A' },
+                .content = .{ .codepoint = .{ .data = 'A' } },
             };
             try page.appendGrapheme(rac.row, rac.cell, @as(u21, @intCast(0x0301)));
         }
@@ -16683,7 +16704,7 @@ test "PageList resize reflow grapheme map capacity exceeded" {
             const rac = page.getRowAndCell(0, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 'B' },
+                .content = .{ .codepoint = .{ .data = 'B' } },
             };
             try page.appendGrapheme(rac.row, rac.cell, @as(u21, @intCast(0x0302)));
         }
@@ -16731,7 +16752,7 @@ test "PageList resize grow cols with unwrap fixes viewport pin" {
             for (0..s.cols) |x| {
                 page.getRowAndCell(x, y).cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = 'A' },
+                    .content = .{ .codepoint = .{ .data = 'A' } },
                 };
             }
         }
@@ -16937,7 +16958,7 @@ test "PageList resize (no reflow) more cols remaps pins in backfill path" {
     const marker: u21 = 'X';
     tracked.rowAndCell().cell.* = .{
         .content_tag = .codepoint,
-        .content = .{ .codepoint = marker },
+        .content = .{ .codepoint = .{ .data = marker } },
     };
 
     try s.resize(.{ .cols = new_cols, .reflow = false });
@@ -16957,7 +16978,7 @@ test "PageList resize (no reflow) more cols remaps pins in backfill path" {
     // Verify the pin still points to the cell with our marker content.
     const cell = tracked.rowAndCell().cell;
     try testing.expectEqual(.codepoint, cell.content_tag);
-    try testing.expectEqual(marker, cell.content.codepoint);
+    try testing.expectEqual(marker, cell.content.codepoint.data);
 }
 
 test "PageList compact pool page produces exact-size heap page" {
@@ -17041,7 +17062,7 @@ test "PageList compact then clone" {
         const rac = node.page().getRowAndCell(1, 2);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'X' },
+            .content = .{ .codepoint = .{ .data = 'X' } },
         };
     }
 
@@ -17060,7 +17081,7 @@ test "PageList compact then clone" {
     {
         const node2 = s2.pages.first.?;
         const rac = node2.page().getRowAndCell(1, 2);
-        try testing.expectEqual(@as(u21, 'X'), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'X'), rac.cell.content.codepoint.data);
     }
 }
 
@@ -17091,7 +17112,7 @@ test "PageList compact oversized page" {
                 const rac = page.getRowAndCell(x, y);
                 rac.cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = @intCast(x + y * s.cols) },
+                    .content = .{ .codepoint = .{ .data = @intCast(x + y * s.cols) } },
                 };
             }
         }
@@ -17145,7 +17166,7 @@ test "PageList compact oversized page" {
             const rac = page.getRowAndCell(x, y);
             try testing.expectEqual(
                 @as(u21, @intCast(x + y * s.cols)),
-                rac.cell.content.codepoint,
+                rac.cell.content.codepoint.data,
             );
         }
     }
@@ -17251,7 +17272,7 @@ test "PageList split at middle row" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -17274,13 +17295,13 @@ test "PageList split at middle row" {
     // Verify content in first page is preserved (rows 0-4 have codepoints 0-4)
     for (0..5) |y| {
         const rac = first_page.getRowAndCell(0, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 
     // Verify content in second page (original rows 5-9, now at y=0-4)
     for (0..5) |y| {
         const rac = second_page.getRowAndCell(0, y);
-        try testing.expectEqual(@as(u21, @intCast(y + 5)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y + 5)), rac.cell.content.codepoint.data);
     }
 }
 
@@ -17298,7 +17319,7 @@ test "PageList split at row 0 is no-op" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -17314,7 +17335,7 @@ test "PageList split at row 0 is no-op" {
     try testing.expectEqual(@as(usize, 10), page.size.rows);
     for (0..10) |y| {
         const rac = page.getRowAndCell(0, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 }
 
@@ -17332,7 +17353,7 @@ test "PageList split at last row" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -17354,7 +17375,7 @@ test "PageList split at last row" {
 
     // Verify content in second page (original row 9, now at y=0)
     const rac = second_page.getRowAndCell(0, 0);
-    try testing.expectEqual(@as(u21, 9), rac.cell.content.codepoint);
+    try testing.expectEqual(@as(u21, 9), rac.cell.content.codepoint.data);
 }
 
 test "PageList split single row page returns OutOfSpace" {
@@ -17700,7 +17721,7 @@ test "PageList split preserves styled cells" {
         const rac = page.getRowAndCell(0, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'S' },
+            .content = .{ .codepoint = .{ .data = 'S' } },
             .style_id = style_id,
         };
         rac.row.styled = true;
@@ -17725,7 +17746,7 @@ test "PageList split preserves styled cells" {
     // Verify styled cells are preserved in new page
     for (0..3) |y| {
         const rac = second_page.getRowAndCell(0, y);
-        try testing.expectEqual(@as(u21, 'S'), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'S'), rac.cell.content.codepoint.data);
         try testing.expect(rac.cell.style_id != 0);
 
         const got_style = second_page.styles.get(second_page.memory, rac.cell.style_id);
@@ -17748,7 +17769,7 @@ test "PageList split preserves grapheme clusters" {
         const rac = page.getRowAndCell(0, 6);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 0x1F468 }, // Man emoji
+            .content = .{ .codepoint = .{ .data = 0x1F468 } }, // Man emoji
         };
         try page.setGraphemes(rac.row, rac.cell, &.{
             0x200D, // ZWJ
@@ -17772,7 +17793,7 @@ test "PageList split preserves grapheme clusters" {
     // Verify grapheme is preserved in new page (original row 6 is now row 1)
     {
         const rac = second_page.getRowAndCell(0, 1);
-        try testing.expectEqual(@as(u21, 0x1F468), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F468), rac.cell.content.codepoint.data);
         try testing.expect(rac.row.grapheme);
 
         const cps = second_page.lookupGrapheme(rac.cell).?;
@@ -17800,7 +17821,7 @@ test "PageList split preserves hyperlinks" {
         const rac = page.getRowAndCell(0, 7);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'L' },
+            .content = .{ .codepoint = .{ .data = 'L' } },
         };
         try page.setHyperlink(rac.row, rac.cell, hyperlink_id);
     }
@@ -17821,7 +17842,7 @@ test "PageList split preserves hyperlinks" {
     // Verify hyperlink is preserved in new page (original row 7 is now row 2)
     {
         const rac = second_page.getRowAndCell(0, 2);
-        try testing.expectEqual(@as(u21, 'L'), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'L'), rac.cell.content.codepoint.data);
         try testing.expect(rac.cell.hyperlink);
 
         const link_id = second_page.lookupHyperlink(rac.cell).?;
diff --git a/src/terminal/Screen.zig b/src/terminal/Screen.zig
index 85c33100f..9ba3a56f4 100644
--- a/src/terminal/Screen.zig
+++ b/src/terminal/Screen.zig
@@ -32,6 +32,9 @@ pub const CursorStyle = @import("cursor.zig").Style;
 
 const log = std.log.scoped(.screen);
 
+/// The I/O implementation to use for any operation that requires one.
+io: std.Io,
+
 /// The general purpose allocator to use for all memory allocations.
 /// Unfortunately some screen operations do require allocation.
 alloc: Allocator,
@@ -285,6 +288,7 @@ pub const Options = struct {
 ///
 /// If max scrollback is 0, then no scrollback is kept at all.
 pub fn init(
+    io: std.Io,
     alloc: Allocator,
     opts: Options,
 ) Allocator.Error!Screen {
@@ -303,6 +307,7 @@ pub fn init(
     const page_rac = page_pin.rowAndCell();
 
     var result: Screen = .{
+        .io = io,
         .alloc = alloc,
         .pages = pages,
         .no_scrollback = opts.max_scrollback == 0,
@@ -319,6 +324,7 @@ pub fn init(
         // This can't fail because the storage is always empty at this point
         // and the only fail-able case is that we have to evict images.
         result.kitty_images.setLimit(
+            io,
             alloc,
             &result,
             opts.kitty_image_storage_limit,
@@ -441,6 +447,7 @@ pub fn reset(self: *Screen) void {
 ///
 pub fn clone(
     self: *const Screen,
+    io: std.Io,
     alloc: Allocator,
     top: point.Point,
     bot: ?point.Point,
@@ -565,6 +572,7 @@ pub fn clone(
     } else null;
 
     const result: Screen = .{
+        .io = io,
         .alloc = alloc,
         .pages = pages,
         .no_scrollback = self.no_scrollback,
@@ -3063,7 +3071,7 @@ pub fn selectLine(self: *const Screen, opts: SelectLine) ?Selection {
             const this_whitespace = std.mem.indexOfScalar(
                 u21,
                 whitespace,
-                cell.content.codepoint,
+                cell.content.codepoint.data,
             ) != null;
             if (this_whitespace) continue;
 
@@ -3085,7 +3093,7 @@ pub fn selectLine(self: *const Screen, opts: SelectLine) ?Selection {
             const this_whitespace = std.mem.indexOfScalar(
                 u21,
                 whitespace,
-                cell.content.codepoint,
+                cell.content.codepoint.data,
             ) != null;
             if (this_whitespace) continue;
 
@@ -3117,7 +3125,7 @@ pub fn selectAll(self: *Screen) ?Selection {
             const this_whitespace = std.mem.indexOfAny(
                 u32,
                 whitespace,
-                &[_]u32{cell.content.codepoint},
+                &[_]u32{cell.content.codepoint.data},
             ) != null;
             if (this_whitespace) continue;
 
@@ -3141,7 +3149,7 @@ pub fn selectAll(self: *Screen) ?Selection {
             const this_whitespace = std.mem.indexOfAny(
                 u32,
                 whitespace,
-                &[_]u32{cell.content.codepoint},
+                &[_]u32{cell.content.codepoint.data},
             ) != null;
             if (this_whitespace) continue;
 
@@ -3209,7 +3217,7 @@ pub fn selectWord(
     const expect_boundary = std.mem.indexOfScalar(
         u21,
         boundary_codepoints,
-        start_cell.content.codepoint,
+        start_cell.content.codepoint.data,
     ) != null;
 
     // Go forwards to find our end boundary
@@ -3227,7 +3235,7 @@ pub fn selectWord(
             const this_boundary = std.mem.indexOfScalar(
                 u21,
                 boundary_codepoints,
-                cell.content.codepoint,
+                cell.content.codepoint.data,
             ) != null;
             if (this_boundary != expect_boundary) break :end prev;
 
@@ -3264,7 +3272,7 @@ pub fn selectWord(
             const this_boundary = std.mem.indexOfScalar(
                 u21,
                 boundary_codepoints,
-                cell.content.codepoint,
+                cell.content.codepoint.data,
             ) != null;
             if (this_boundary != expect_boundary) break :start prev;
 
@@ -3686,7 +3694,7 @@ pub fn testWriteString(self: *Screen, text: []const u8) !void {
             1 => {
                 self.cursor.page_cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = c },
+                    .content = .{ .codepoint = @bitCast(@as(u24, @intCast(c))) },
                     .style_id = self.cursor.style_id,
                     .protected = self.cursor.protected,
                     .semantic_content = self.cursor.semantic_content,
@@ -3708,7 +3716,7 @@ pub fn testWriteString(self: *Screen, text: []const u8) !void {
                 if (self.cursor.x == self.pages.cols - 1) {
                     self.cursor.page_cell.* = .{
                         .content_tag = .codepoint,
-                        .content = .{ .codepoint = 0 },
+                        .content = .{ .codepoint = .{ .data = 0 } },
                         .wide = .spacer_head,
                         .protected = self.cursor.protected,
                         .semantic_content = self.cursor.semantic_content,
@@ -3726,7 +3734,7 @@ pub fn testWriteString(self: *Screen, text: []const u8) !void {
                 // Write our wide char
                 self.cursor.page_cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = c },
+                    .content = .{ .codepoint = .{ .data = c } },
                     .style_id = self.cursor.style_id,
                     .wide = .wide,
                     .protected = self.cursor.protected,
@@ -3740,7 +3748,7 @@ pub fn testWriteString(self: *Screen, text: []const u8) !void {
                 self.cursorRight(1);
                 self.cursor.page_cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = 0 },
+                    .content = .{ .codepoint = .{ .data = 0 } },
                     .wide = .spacer_tail,
                     .protected = self.cursor.protected,
                     .semantic_content = self.cursor.semantic_content,
@@ -3772,8 +3780,9 @@ pub fn testWriteString(self: *Screen, text: []const u8) !void {
 test "Screen read and write" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
     try testing.expectEqual(@as(style.Id, 0), s.cursor.style_id);
 
@@ -3786,8 +3795,9 @@ test "Screen read and write" {
 test "Screen read and write newline" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
     try testing.expectEqual(@as(style.Id, 0), s.cursor.style_id);
 
@@ -3800,8 +3810,9 @@ test "Screen read and write newline" {
 test "Screen read and write scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 2, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 2, .max_scrollback = 1000 });
     defer s.deinit();
 
     try s.testWriteString("hello\nworld\ntest");
@@ -3820,8 +3831,9 @@ test "Screen read and write scrollback" {
 test "Screen read and write no scrollback small" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 2, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
 
     try s.testWriteString("hello\nworld\ntest");
@@ -3840,8 +3852,9 @@ test "Screen read and write no scrollback small" {
 test "Screen read and write no scrollback large" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 2, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
 
     for (0..1_000) |i| {
@@ -3861,14 +3874,15 @@ test "Screen read and write no scrollback large" {
 test "Screen cursorCopy x/y" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     s.cursorAbsolute(2, 3);
     try testing.expect(s.cursor.x == 2);
     try testing.expect(s.cursor.y == 3);
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s2.deinit();
     try s2.cursorCopy(s.cursor, .{});
     try testing.expect(s2.cursor.x == 2);
@@ -3885,11 +3899,12 @@ test "Screen cursorCopy x/y" {
 test "Screen cursorCopy style deref" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s2.deinit();
     const page = s2.cursor.page_pin.node.page();
 
@@ -3907,11 +3922,12 @@ test "Screen cursorCopy style deref" {
 test "Screen cursorCopy style deref new page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 2048 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 2048 });
     defer s2.deinit();
 
     // We need to get the cursor on a new page.
@@ -3980,12 +3996,13 @@ test "Screen cursorCopy style deref new page" {
 test "Screen cursorCopy style copy" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.setAttribute(.{ .bold = {} });
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s2.deinit();
     const page = s2.cursor.page_pin.node.page();
     try s2.cursorCopy(s.cursor, .{});
@@ -3996,11 +4013,12 @@ test "Screen cursorCopy style copy" {
 test "Screen cursorCopy hyperlink deref" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s2.deinit();
     const page = s2.cursor.page_pin.node.page();
 
@@ -4018,8 +4036,9 @@ test "Screen cursorCopy hyperlink deref" {
 test "Screen write regrows compacted page capacity" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{
+    var s = try Screen.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
         .max_scrollback = 0,
@@ -4066,11 +4085,12 @@ test "Screen write regrows compacted page capacity" {
 test "Screen cursorCopy hyperlink deref new page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 2048 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 2048 });
     defer s2.deinit();
 
     // We need to get the cursor on a new page.
@@ -4139,8 +4159,9 @@ test "Screen cursorCopy hyperlink deref new page" {
 test "Screen cursorCopy hyperlink copy" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
     // Create a hyperlink for the cursor.
@@ -4148,7 +4169,7 @@ test "Screen cursorCopy hyperlink copy" {
     try testing.expectEqual(@as(usize, 1), s.cursor.page_pin.node.page().hyperlink_set.count());
     try testing.expect(s.cursor.hyperlink_id != 0);
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s2.deinit();
     const page = s2.cursor.page_pin.node.page();
 
@@ -4164,8 +4185,9 @@ test "Screen cursorCopy hyperlink copy" {
 test "Screen cursorCopy hyperlink copy disabled" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
     // Create a hyperlink for the cursor.
@@ -4173,7 +4195,7 @@ test "Screen cursorCopy hyperlink copy disabled" {
     try testing.expectEqual(@as(usize, 1), s.cursor.page_pin.node.page().hyperlink_set.count());
     try testing.expect(s.cursor.hyperlink_id != 0);
 
-    var s2 = try Screen.init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s2 = try Screen.init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s2.deinit();
     const page = s2.cursor.page_pin.node.page();
 
@@ -4189,8 +4211,9 @@ test "Screen cursorCopy hyperlink copy disabled" {
 test "Screen style basics" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
     const page = s.cursor.page_pin.node.page();
     try testing.expectEqual(@as(usize, 0), page.styles.count());
@@ -4211,8 +4234,9 @@ test "Screen style basics" {
 test "Screen style reset to default" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
     const page = s.cursor.page_pin.node.page();
     try testing.expectEqual(@as(usize, 0), page.styles.count());
@@ -4231,8 +4255,9 @@ test "Screen style reset to default" {
 test "Screen style reset with unset" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
     const page = s.cursor.page_pin.node.page();
     try testing.expectEqual(@as(usize, 0), page.styles.count());
@@ -4251,8 +4276,9 @@ test "Screen style reset with unset" {
 test "Screen clearRows active one line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     try s.testWriteString("hello, world");
@@ -4266,8 +4292,9 @@ test "Screen clearRows active one line" {
 test "Screen clearRows active multi line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     try s.testWriteString("hello\nworld");
@@ -4282,8 +4309,9 @@ test "Screen clearRows active multi line" {
 test "Screen clearRows active styled line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     try s.setAttribute(.{ .bold = {} });
@@ -4307,7 +4335,7 @@ test "Screen clearRows active styled line" {
 test "Screen clearCells empty range" {
     const testing = std.testing;
 
-    var s = try Screen.init(testing.allocator, .default);
+    var s = try Screen.init(testing.io, testing.allocator, .default);
     defer s.deinit();
 
     const page = s.cursor.page_pin.node.page();
@@ -4319,7 +4347,7 @@ test "Screen clearCells empty range" {
 test "Screen clearRows uses stored page width" {
     const testing = std.testing;
 
-    var s = try Screen.init(testing.allocator, .{
+    var s = try Screen.init(testing.io, testing.allocator, .{
         .cols = 2,
         .rows = 1,
         .max_scrollback = 0,
@@ -4339,8 +4367,9 @@ test "Screen clearRows uses stored page width" {
 test "Screen clearRows protected" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     try s.testWriteString("UNPROTECTED");
@@ -4367,8 +4396,9 @@ test "Screen clearRows protected" {
 test "Screen eraseRows history" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 1000 });
     defer s.deinit();
 
     try s.testWriteString("1\n2\n3\n4\n5\n6");
@@ -4401,8 +4431,9 @@ test "Screen eraseRows history" {
 test "Screen eraseRows history with more lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 1000 });
     defer s.deinit();
 
     try s.testWriteString("A\nB\nC\n1\n2\n3\n4\n5\n6");
@@ -4435,8 +4466,9 @@ test "Screen eraseRows history with more lines" {
 test "Screen eraseRows active partial" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     try s.testWriteString("1\n2\n3");
@@ -4463,7 +4495,7 @@ test "Screen eraseRows active partial" {
 
 test "Screen: cursorCellEndOfPrev across mixed-width pages" {
     const testing = std.testing;
-    var s = try init(testing.allocator, .{
+    var s = try init(testing.io, testing.allocator, .{
         .cols = 4,
         .rows = 2,
         .max_scrollback = 0,
@@ -4485,8 +4517,9 @@ test "Screen: cursorCellEndOfPrev across mixed-width pages" {
 test "Screen: cursorDown across pages preserves style" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
 
     // Scroll down enough to go to another page
@@ -4537,8 +4570,9 @@ test "Screen: cursorDown across pages preserves style" {
 test "Screen: cursorUp across pages preserves style" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
 
     // Scroll down enough to go to another page
@@ -4584,8 +4618,9 @@ test "Screen: cursorUp across pages preserves style" {
 test "Screen: cursorAbsolute across pages preserves style" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
 
     // Scroll down enough to go to another page
@@ -4639,8 +4674,9 @@ test "Screen: cursorAbsolute to page with insufficient capacity" {
 
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
 
     // Scroll down enough to go to another page
@@ -4706,8 +4742,9 @@ test "Screen: cursorAbsolute to page with insufficient capacity" {
 test "Screen: scrolling" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     try s.setAttribute(.{ .direct_color_bg = .{ .r = 155 } });
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
@@ -4748,8 +4785,9 @@ test "Screen: scrolling" {
 test "Screen: scrolling with a single-row screen no scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 1, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 1, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABCD");
 
@@ -4768,8 +4806,9 @@ test "Screen: scrolling with a single-row screen no scrollback" {
 test "Screen: scrolling with a single-row screen with scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 1, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 1, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD");
 
@@ -4798,8 +4837,9 @@ test "Screen: scrolling with a single-row screen with scrollback" {
 test "Screen: scrolling across pages preserves style" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.setAttribute(.{ .bold = {} });
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
@@ -4827,8 +4867,9 @@ test "Screen: scrolling across pages preserves style" {
 test "Screen: scroll down from 0" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -4846,8 +4887,9 @@ test "Screen: scroll down from 0" {
 test "Screen: scrollback various cases" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
     try s.cursorDownScroll();
@@ -4927,8 +4969,9 @@ test "Screen: scrollback various cases" {
 test "Screen: scrollback with multi-row delta" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH\n6IJKL");
 
@@ -4953,8 +4996,9 @@ test "Screen: scrollback with multi-row delta" {
 test "Screen: scrollback empty" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 50 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 50 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
     s.scroll(.{ .delta_row = 1 });
@@ -4968,8 +5012,9 @@ test "Screen: scrollback empty" {
 test "Screen: scrollback doesn't move viewport if not at bottom" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH");
 
@@ -5003,8 +5048,9 @@ test "Screen: scrollback doesn't move viewport if not at bottom" {
 test "Screen: scrolling moves selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -5082,8 +5128,9 @@ test "Screen: scrolling moves selection" {
 test "Screen: cursorScrollRegionUp simple" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4MNOP\n5QRST");
 
@@ -5109,8 +5156,9 @@ test "Screen: cursorScrollRegionUp simple" {
 test "Screen: cursorScrollRegionUp renews page generation" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4MNOP\n5QRST");
     s.cursorAbsolute(0, 2);
@@ -5125,8 +5173,9 @@ test "Screen: cursorScrollRegionUp renews page generation" {
 test "Screen: cursorScrollRegionUp moves selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4MNOP\n5QRST");
 
@@ -5163,8 +5212,9 @@ test "Screen: cursorScrollRegionUp moves selection" {
 test "Screen: cursorScrollRegionUp region spans pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
     defer s.deinit();
 
     // We need to get the cursor to a new page
@@ -5227,8 +5277,9 @@ test "Screen: cursorScrollRegionUp region spans pages" {
 test "Screen: cursorScrollRegionUp region spans pages with background SGR" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
     defer s.deinit();
 
     // We need to get the cursor to a new page. See the previous test
@@ -5270,8 +5321,9 @@ test "Screen: cursorScrollRegionUp region spans pages with background SGR" {
 test "Screen: cursorScrollRegionUp with styled erased row" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
 
     // Write a styled row at the top so the erased row has managed
@@ -5299,8 +5351,9 @@ test "Screen: cursorScrollRegionUp with styled erased row" {
 test "Screen: scrolling moves viewport" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n");
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
@@ -5324,8 +5377,9 @@ test "Screen: scrolling moves viewport" {
 test "Screen: scrolling when viewport is pruned" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 215, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 215, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
 
     // Write some to create scrollback and move back into our scrollback.
@@ -5350,8 +5404,9 @@ test "Screen: scrolling when viewport is pruned" {
 test "Screen: scroll and clear full screen" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -5377,8 +5432,9 @@ test "Screen: scroll and clear full screen" {
 test "Screen: scroll and clear partial screen" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH");
 
@@ -5404,8 +5460,9 @@ test "Screen: scroll and clear partial screen" {
 test "Screen: scroll and clear empty screen" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     try s.scrollClear();
     {
@@ -5423,8 +5480,9 @@ test "Screen: scroll and clear empty screen" {
 test "Screen: scroll and clear ignore blank lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH");
     try s.scrollClear();
@@ -5466,8 +5524,9 @@ test "Screen: scroll and clear ignore blank lines" {
 test "Screen: scroll above same page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     try s.setAttribute(.{ .direct_color_bg = .{ .r = 155 } });
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
@@ -5528,8 +5587,9 @@ test "Screen: scroll above same page" {
 test "Screen: scroll above same page but cursor on previous page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
     defer s.deinit();
 
     // We need to get the cursor to a new page
@@ -5615,8 +5675,9 @@ test "Screen: scroll above same page but cursor on previous page" {
 test "Screen: scroll above same page but cursor on previous page last row" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
     defer s.deinit();
 
     // We need to get the cursor to a new page
@@ -5705,8 +5766,9 @@ test "Screen: scroll above same page but cursor on previous page last row" {
 test "Screen: scroll above creates new page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
 
     // We need to get the cursor to a new page
@@ -5780,8 +5842,9 @@ test "Screen: scroll above creates new page" {
 test "Screen: scroll above with cursor on non-final row" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 4, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 4, .max_scrollback = 10 });
     defer s.deinit();
 
     // Get the cursor to be 2 rows above a new page
@@ -5857,8 +5920,9 @@ test "Screen: scroll above with cursor on non-final row" {
 test "Screen: scroll above no scrollback bottom of page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
 
     const first_page_size = s.pages.pages.first.?.capacity().rows;
@@ -5930,8 +5994,9 @@ test "Screen: scroll above hyperlink-dense row to fresh page" {
     // half-mutated and aborts later (e.g. in clearCells).
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10000 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10000 });
     defer s.deinit();
 
     // Fill the first page so it is exactly full and the cursor is on
@@ -6018,8 +6083,9 @@ test "Screen: scroll above hyperlink-dense row to existing page" {
     // already exists (fresh_node == null path in cursorScrollAboveRotate).
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10000 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10000 });
     defer s.deinit();
 
     // Fill the first page so it is exactly full and the cursor is on
@@ -6083,8 +6149,9 @@ test "Screen: scroll above hyperlink-dense row to existing page" {
 test "Screen: clone" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH");
     {
@@ -6096,7 +6163,7 @@ test "Screen: clone" {
     try testing.expectEqual(@as(usize, 1), s.cursor.y);
 
     // Clone
-    var s2 = try s.clone(alloc, .{ .active = .{} }, null);
+    var s2 = try s.clone(io, alloc, .{ .active = .{} }, null);
     defer s2.deinit();
     {
         const contents = try s2.dumpStringAlloc(alloc, .{ .active = .{} });
@@ -6125,8 +6192,9 @@ test "Screen: clone" {
 test "Screen: clone partial" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH");
     {
@@ -6138,7 +6206,7 @@ test "Screen: clone partial" {
     try testing.expectEqual(@as(usize, 1), s.cursor.y);
 
     // Clone
-    var s2 = try s.clone(alloc, .{ .active = .{ .y = 1 } }, null);
+    var s2 = try s.clone(io, alloc, .{ .active = .{ .y = 1 } }, null);
     defer s2.deinit();
     {
         const contents = try s2.dumpStringAlloc(alloc, .{ .active = .{} });
@@ -6154,8 +6222,9 @@ test "Screen: clone partial" {
 test "Screen: clone partial cursor out of bounds" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH");
     {
@@ -6168,6 +6237,7 @@ test "Screen: clone partial cursor out of bounds" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{ .y = 0 } },
         .{ .active = .{ .y = 0 } },
@@ -6187,8 +6257,9 @@ test "Screen: clone partial cursor out of bounds" {
 test "Screen: clone contains full selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -6201,6 +6272,7 @@ test "Screen: clone contains full selection" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{} },
         null,
@@ -6224,8 +6296,9 @@ test "Screen: clone contains full selection" {
 test "Screen: clone contains none of selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -6238,6 +6311,7 @@ test "Screen: clone contains none of selection" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{ .y = 1 } },
         null,
@@ -6251,8 +6325,9 @@ test "Screen: clone contains none of selection" {
 test "Screen: clone contains selection start cutoff" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -6265,6 +6340,7 @@ test "Screen: clone contains selection start cutoff" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{ .y = 1 } },
         null,
@@ -6288,8 +6364,9 @@ test "Screen: clone contains selection start cutoff" {
 test "Screen: clone contains selection end cutoff" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -6302,6 +6379,7 @@ test "Screen: clone contains selection end cutoff" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{ .y = 0 } },
         .{ .active = .{ .y = 1 } },
@@ -6325,8 +6403,9 @@ test "Screen: clone contains selection end cutoff" {
 test "Screen: clone contains selection end cutoff reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
@@ -6339,6 +6418,7 @@ test "Screen: clone contains selection end cutoff reversed" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{ .y = 0 } },
         .{ .active = .{ .y = 1 } },
@@ -6362,8 +6442,9 @@ test "Screen: clone contains selection end cutoff reversed" {
 test "Screen: clone contains subset of selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 4, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 4, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4ABCD");
 
@@ -6376,6 +6457,7 @@ test "Screen: clone contains subset of selection" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{ .y = 1 } },
         .{ .active = .{ .y = 2 } },
@@ -6399,8 +6481,9 @@ test "Screen: clone contains subset of selection" {
 test "Screen: clone clamps clipped selections to mixed-width pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 4, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 4, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
 
     const first = s.pages.pages.first.?;
@@ -6416,6 +6499,7 @@ test "Screen: clone clamps clipped selections to mixed-width pages" {
         false,
     ));
     var linear = try s.clone(
+        io,
         alloc,
         .{ .screen = .{} },
         .{ .screen = .{ .y = 1 } },
@@ -6431,6 +6515,7 @@ test "Screen: clone clamps clipped selections to mixed-width pages" {
         true,
     ));
     var rectangle = try s.clone(
+        io,
         alloc,
         .{ .screen = .{ .y = 1 } },
         null,
@@ -6444,8 +6529,9 @@ test "Screen: clone clamps clipped selections to mixed-width pages" {
 test "Screen: clone contains subset of rectangle selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 4, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 4, .max_scrollback = 1 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4ABCD");
 
@@ -6458,6 +6544,7 @@ test "Screen: clone contains subset of rectangle selection" {
 
     // Clone
     var s2 = try s.clone(
+        io,
         alloc,
         .{ .active = .{ .y = 1 } },
         .{ .active = .{ .y = 2 } },
@@ -6483,13 +6570,15 @@ test "Screen: clone contains subset of rectangle selection" {
 test "Screen: clone basic" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL");
 
     {
         var s2 = try s.clone(
+            io,
             alloc,
             .{ .active = .{ .y = 1 } },
             .{ .active = .{ .y = 1 } },
@@ -6504,6 +6593,7 @@ test "Screen: clone basic" {
 
     {
         var s2 = try s.clone(
+            io,
             alloc,
             .{ .active = .{ .y = 1 } },
             .{ .active = .{ .y = 2 } },
@@ -6520,12 +6610,14 @@ test "Screen: clone basic" {
 test "Screen: clone empty viewport" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
 
     {
         var s2 = try s.clone(
+            io,
             alloc,
             .{ .viewport = .{ .y = 0 } },
             .{ .viewport = .{ .y = 0 } },
@@ -6542,13 +6634,15 @@ test "Screen: clone empty viewport" {
 test "Screen: clone one line viewport" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABC");
 
     {
         var s2 = try s.clone(
+            io,
             alloc,
             .{ .viewport = .{ .y = 0 } },
             .{ .viewport = .{ .y = 0 } },
@@ -6565,12 +6659,14 @@ test "Screen: clone one line viewport" {
 test "Screen: clone empty active" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
 
     {
         var s2 = try s.clone(
+            io,
             alloc,
             .{ .active = .{ .y = 0 } },
             .{ .active = .{ .y = 0 } },
@@ -6587,13 +6683,15 @@ test "Screen: clone empty active" {
 test "Screen: clone one line active with extra space" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABC");
 
     {
         var s2 = try s.clone(
+            io,
             alloc,
             .{ .active = .{ .y = 0 } },
             null,
@@ -6610,8 +6708,9 @@ test "Screen: clone one line active with extra space" {
 test "Screen: clear history with no history" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     try s.testWriteString("4ABCD\n5EFGH\n6IJKL");
     try testing.expect(s.pages.viewport == .active);
@@ -6634,8 +6733,9 @@ test "Screen: clear history with no history" {
 test "Screen: clear history" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH\n6IJKL");
     try testing.expect(s.pages.viewport == .active);
@@ -6668,8 +6768,9 @@ test "Screen: clear history" {
 test "Screen: clear above cursor" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 3 });
     defer s.deinit();
     try s.testWriteString("4ABCD\n5EFGH\n6IJKL");
     s.clearRows(
@@ -6695,8 +6796,9 @@ test "Screen: clear above cursor" {
 test "Screen: clear above cursor with history" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     try s.testWriteString("1ABCD\n2EFGH\n3IJKL\n");
     try s.testWriteString("4ABCD\n5EFGH\n6IJKL");
@@ -6723,8 +6825,9 @@ test "Screen: clear above cursor with history" {
 test "Screen: resize (no reflow) more rows" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -6741,8 +6844,9 @@ test "Screen: resize (no reflow) more rows" {
 test "Screen: resize (no reflow) less rows" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -6764,8 +6868,9 @@ test "Screen: resize (no reflow) less rows" {
 test "Screen: resize (no reflow) less rows trims blank lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD";
     try s.testWriteString(str);
@@ -6799,8 +6904,9 @@ test "Screen: resize (no reflow) less rows trims blank lines" {
 test "Screen: resize (no reflow) more rows trims blank lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD";
     try s.testWriteString(str);
@@ -6834,8 +6940,9 @@ test "Screen: resize (no reflow) more rows trims blank lines" {
 test "Screen: resize (no reflow) more cols" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -6851,8 +6958,9 @@ test "Screen: resize (no reflow) more cols" {
 test "Screen: resize (no reflow) less cols" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -6869,8 +6977,9 @@ test "Screen: resize (no reflow) less cols" {
 test "Screen: resize (no reflow) more rows with scrollback cursor end" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 7, .rows = 3, .max_scrollback = 2 });
+    var s = try init(io, alloc, .{ .cols = 7, .rows = 3, .max_scrollback = 2 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH";
     try s.testWriteString(str);
@@ -6886,8 +6995,9 @@ test "Screen: resize (no reflow) more rows with scrollback cursor end" {
 test "Screen: resize (no reflow) less rows with scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 7, .rows = 3, .max_scrollback = 2 });
+    var s = try init(io, alloc, .{ .cols = 7, .rows = 3, .max_scrollback = 2 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH";
     try s.testWriteString(str);
@@ -6905,8 +7015,9 @@ test "Screen: resize (no reflow) less rows with scrollback" {
 test "Screen: resize (no reflow) less rows with empty trailing" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1\n2\n3\n4\n5\n6\n7\n8";
     try s.testWriteString(str);
@@ -6929,8 +7040,9 @@ test "Screen: resize (no reflow) less rows with empty trailing" {
 test "Screen: resize (no reflow) more rows with soft wrapping" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 2, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 2, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     const str = "1A2B\n3C4E\n5F6G";
     try s.testWriteString(str);
@@ -6970,8 +7082,9 @@ test "Screen: resize (no reflow) more rows with soft wrapping" {
 test "Screen: resize more rows no scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -6997,8 +7110,9 @@ test "Screen: resize more rows no scrollback" {
 test "Screen: resize more rows with empty scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7024,8 +7138,9 @@ test "Screen: resize more rows with empty scrollback" {
 test "Screen: resize more rows with populated scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH";
     try s.testWriteString(str);
@@ -7043,7 +7158,7 @@ test "Screen: resize more rows with populated scrollback" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '4'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '4'), list_cell.cell.content.codepoint.data);
     }
 
     // Resize
@@ -7055,7 +7170,7 @@ test "Screen: resize more rows with populated scrollback" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '4'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '4'), list_cell.cell.content.codepoint.data);
     }
 
     {
@@ -7069,8 +7184,9 @@ test "Screen: resize more rows with populated scrollback" {
 test "Screen: resize more cols no reflow" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7098,8 +7214,9 @@ test "Screen: resize more cols no reflow" {
 test "Screen: resize more cols perfect split" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH3IJKL";
     try s.testWriteString(str);
@@ -7116,8 +7233,9 @@ test "Screen: resize more cols perfect split" {
 test "Screen: resize (no reflow) more cols with scrollback scrolled up" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1\n2\n3\n4\n5\n6\n7\n8";
     try s.testWriteString(str);
@@ -7149,8 +7267,9 @@ test "Screen: resize (no reflow) more cols with scrollback scrolled up" {
 test "Screen: resize (no reflow) less cols with scrollback scrolled up" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1\n2\n3\n4\n5\n6\n7\n8";
     try s.testWriteString(str);
@@ -7193,8 +7312,9 @@ test "Screen: resize (no reflow) less cols with scrollback scrolled up" {
 test "Screen: resize more cols no reflow preserves semantic prompt" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
 
     // Set one of the rows to be a prompt
@@ -7237,8 +7357,9 @@ test "Screen: resize more cols no reflow preserves semantic prompt" {
 test "Screen: resize more cols with reflow that fits full width" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7258,7 +7379,7 @@ test "Screen: resize more cols with reflow that fits full width" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '2'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '2'), list_cell.cell.content.codepoint.data);
     }
 
     // Resize and verify we undid the soft wrap because we have space now
@@ -7277,8 +7398,9 @@ test "Screen: resize more cols with reflow that fits full width" {
 test "Screen: resize more cols with reflow that ends in newline" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 6, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 6, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7298,7 +7420,7 @@ test "Screen: resize more cols with reflow that ends in newline" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint.data);
     }
 
     // Resize and verify we undid the soft wrap because we have space now
@@ -7315,15 +7437,16 @@ test "Screen: resize more cols with reflow that ends in newline" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint.data);
     }
 }
 
 test "Screen: resize more cols with reflow that forces more wrapping" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7335,7 +7458,7 @@ test "Screen: resize more cols with reflow that forces more wrapping" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '2'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '2'), list_cell.cell.content.codepoint.data);
     }
 
     // Verify we soft wrapped
@@ -7363,8 +7486,9 @@ test "Screen: resize more cols with reflow that forces more wrapping" {
 test "Screen: resize more cols with reflow that unwraps multiple times" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH3IJKL";
     try s.testWriteString(str);
@@ -7376,7 +7500,7 @@ test "Screen: resize more cols with reflow that unwraps multiple times" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint.data);
     }
 
     // Verify we soft wrapped
@@ -7404,8 +7528,9 @@ test "Screen: resize more cols with reflow that unwraps multiple times" {
 test "Screen: resize more cols with populated scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL\n4ABCD5EFGH";
     try s.testWriteString(str);
@@ -7423,7 +7548,7 @@ test "Screen: resize more cols with populated scrollback" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '5'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '5'), list_cell.cell.content.codepoint.data);
     }
 
     // Resize
@@ -7441,7 +7566,7 @@ test "Screen: resize more cols with populated scrollback" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u21, '5'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '5'), list_cell.cell.content.codepoint.data);
     }
 }
 
@@ -7453,8 +7578,9 @@ test "Screen: resize more cols bounded scrollback keeps viewport valid" {
     // resize path. A direct PageList resize repro does not hit the same bug.
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 2,
         .rows = 10,
         .max_scrollback = 10_000,
@@ -7488,7 +7614,7 @@ test "Screen: resize more cols bounded scrollback keeps viewport valid" {
             for (0..s.pages.cols) |x| {
                 page.getRowAndCell(x, y).cell.* = .{
                     .content_tag = .codepoint,
-                    .content = .{ .codepoint = 'A' },
+                    .content = .{ .codepoint = @bitCast(@as(u24, 'A')) },
                 };
             }
         }
@@ -7528,8 +7654,9 @@ test "Screen: resize more cols bounded scrollback keeps viewport valid" {
 test "Screen: resize more cols with reflow" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 2, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 2, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1ABC\n2DEF\n3ABC\n4DEF";
     try s.testWriteString(str);
@@ -7541,7 +7668,7 @@ test "Screen: resize more cols with reflow" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u32, 'E'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'E'), list_cell.cell.content.codepoint.data);
     }
 
     // Verify we soft wrapped
@@ -7569,12 +7696,13 @@ test "Screen: resize more cols with reflow" {
 test "Screen: resize errors preserve state" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     for (std.meta.tags(resize_tw.FailPoint)) |tag| {
         const tw = resize_tw;
         defer tw.end(.reset) catch unreachable;
 
-        var s = try init(alloc, .{
+        var s = try init(io, alloc, .{
             .cols = 10,
             .rows = 3,
             .max_scrollback = 0,
@@ -7654,8 +7782,9 @@ test "Screen: resize errors preserve state" {
 test "Screen: resize cursor references when node survives" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 5,
         .rows = 3,
         .max_scrollback = 1000,
@@ -7703,8 +7832,9 @@ test "Screen: resize cursor references when node survives" {
 test "Screen: resize cursor references when node is replaced" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 5,
         .rows = 3,
         .max_scrollback = 1000,
@@ -7754,8 +7884,9 @@ test "Screen: resize cursor references when node is replaced" {
 test "Screen: resize more rows and cols with wrapping" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 2, .rows = 4, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 2, .rows = 4, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1A2B\n3C4D";
     try s.testWriteString(str);
@@ -7787,8 +7918,9 @@ test "Screen: resize more rows and cols with wrapping" {
 test "Screen: resize less rows no scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7818,8 +7950,9 @@ test "Screen: resize less rows no scrollback" {
 test "Screen: resize less rows moving cursor" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7831,7 +7964,7 @@ test "Screen: resize less rows moving cursor" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u32, 'I'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'I'), list_cell.cell.content.codepoint.data);
     }
 
     // Resize
@@ -7858,8 +7991,9 @@ test "Screen: resize less rows moving cursor" {
 test "Screen: resize less rows with empty scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -7881,8 +8015,9 @@ test "Screen: resize less rows with empty scrollback" {
 test "Screen: resize less rows with populated scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH";
     try s.testWriteString(str);
@@ -7912,8 +8047,9 @@ test "Screen: resize less rows with populated scrollback" {
 test "Screen: resize less rows with full scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     const str = "00000\n1ABCD\n2EFGH\n3IJKL\n4ABCD\n5EFGH";
     try s.testWriteString(str);
@@ -7952,8 +8088,9 @@ test "Screen: resize less rows with full scrollback" {
 test "Screen: resize less cols no reflow" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1AB\n2EF\n3IJ";
     try s.testWriteString(str);
@@ -7981,8 +8118,9 @@ test "Screen: resize less cols no reflow" {
 test "Screen: resize less cols with reflow but row space" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     const str = "1ABCD";
     try s.testWriteString(str);
@@ -7994,7 +8132,7 @@ test "Screen: resize less cols with reflow but row space" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u32, 'D'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'D'), list_cell.cell.content.codepoint.data);
     }
 
     try s.resize(.{ .cols = 3, .rows = 3 });
@@ -8019,8 +8157,9 @@ test "Screen: resize less cols with reflow but row space" {
 test "Screen: resize less cols with reflow with trimmed rows" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "3IJKL\n4ABCD\n5EFGH";
     try s.testWriteString(str);
@@ -8043,8 +8182,9 @@ test "Screen: resize less cols with reflow with trimmed rows" {
 test "Screen: resize less cols with reflow with trimmed rows and scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
     const str = "3IJKL\n4ABCD\n5EFGH";
     try s.testWriteString(str);
@@ -8067,8 +8207,9 @@ test "Screen: resize less cols with reflow with trimmed rows and scrollback" {
 test "Screen: resize less cols with reflow previously wrapped" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "3IJKL4ABCD5EFGH";
     try s.testWriteString(str);
@@ -8100,8 +8241,9 @@ test "Screen: resize less cols with reflow previously wrapped" {
 test "Screen: resize less cols with reflow and scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1A\n2B\n3C\n4D\n5E";
     try s.testWriteString(str);
@@ -8113,7 +8255,7 @@ test "Screen: resize less cols with reflow and scrollback" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u32, 'E'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'E'), list_cell.cell.content.codepoint.data);
     }
 
     try s.resize(.{ .cols = 3, .rows = 3 });
@@ -8133,8 +8275,9 @@ test "Screen: resize less cols with reflow and scrollback" {
 test "Screen: resize less cols with reflow previously wrapped and scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 2 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 2 });
     defer s.deinit();
     const str = "1ABCD2EFGH3IJKL4ABCD5EFGH";
     try s.testWriteString(str);
@@ -8154,7 +8297,7 @@ test "Screen: resize less cols with reflow previously wrapped and scrollback" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u32, 'H'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'H'), list_cell.cell.content.codepoint.data);
     }
 
     try s.resize(.{ .cols = 3, .rows = 3 });
@@ -8180,15 +8323,16 @@ test "Screen: resize less cols with reflow previously wrapped and scrollback" {
             .x = s.cursor.x,
             .y = s.cursor.y,
         } }).?;
-        try testing.expectEqual(@as(u32, 'H'), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'H'), list_cell.cell.content.codepoint.data);
     }
 }
 
 test "Screen: resize less cols with scrollback keeps cursor row" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     const str = "1A\n2B\n3C\n4D\n5E";
     try s.testWriteString(str);
@@ -8216,8 +8360,9 @@ test "Screen: resize less cols with scrollback keeps cursor row" {
 test "Screen: resize more rows, less cols with reflow with scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 3 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 3 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH3IJKL\n4MNOP";
     try s.testWriteString(str);
@@ -8257,8 +8402,9 @@ test "Screen: resize more rows, less cols with reflow with scrollback" {
 test "Screen: resize more rows then shrink again" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
     defer s.deinit();
     const str = "1ABC";
     try s.testWriteString(str);
@@ -8306,8 +8452,9 @@ test "Screen: resize more rows then shrink again" {
 test "Screen: resize less cols to eliminate wide char" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 2, .rows = 1, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 2, .rows = 1, .max_scrollback = 0 });
     defer s.deinit();
     const str = "😀";
     try s.testWriteString(str);
@@ -8320,7 +8467,7 @@ test "Screen: resize less cols to eliminate wide char" {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
-        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint.data);
     }
 
     // Resize to 1 column can't fit a wide char. So it should be deleted.
@@ -8333,7 +8480,7 @@ test "Screen: resize less cols to eliminate wide char" {
     {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
@@ -8341,8 +8488,9 @@ test "Screen: resize less cols to eliminate wide char" {
 test "Screen: resize less cols to wrap wide char" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 3, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 3, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "x😀";
     try s.testWriteString(str);
@@ -8355,7 +8503,7 @@ test "Screen: resize less cols to wrap wide char" {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
-        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint.data);
     }
     {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
@@ -8380,8 +8528,9 @@ test "Screen: resize less cols to wrap wide char" {
 test "Screen: resize less cols to eliminate wide char with row space" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 2, .rows = 2, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 2, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
     const str = "😀";
     try s.testWriteString(str);
@@ -8394,7 +8543,7 @@ test "Screen: resize less cols to eliminate wide char with row space" {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
-        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint.data);
     }
     {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
@@ -8413,7 +8562,8 @@ test "Screen: resize less cols to eliminate wide char with row space" {
 test "Screen: resize less cols reflows cursor after wrapped text" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var s = try Screen.init(alloc, .{ .cols = 50, .rows = 7, .max_scrollback = 0 });
+    const io = testing.io;
+    var s = try Screen.init(io, alloc, .{ .cols = 50, .rows = 7, .max_scrollback = 0 });
     defer s.deinit();
 
     for (0..30) |_| try s.testWriteString("a");
@@ -8430,7 +8580,8 @@ test "Screen: resize less cols reflows cursor after wrapped text" {
 test "Screen: resize less cols reflows cursor after empty cells" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
+    const io = testing.io;
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
 
     try s.testWriteString("abc");
@@ -8448,8 +8599,9 @@ test "Screen: resize less cols reflows cursor after empty cells" {
 test "Screen: resize more cols with wide spacer head" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 3, .rows = 2, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 3, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
     const str = "  😀";
     try s.testWriteString(str);
@@ -8489,7 +8641,7 @@ test "Screen: resize more cols with wide spacer head" {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
-        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint.data);
     }
     {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 3, .y = 0 } }).?;
@@ -8501,8 +8653,9 @@ test "Screen: resize more cols with wide spacer head" {
 test "Screen: resize more cols with wide spacer head multiple lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 3, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 3, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "xxxyy😀";
     try s.testWriteString(str);
@@ -8540,7 +8693,7 @@ test "Screen: resize more cols with wide spacer head multiple lines" {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 5, .y = 0 } }).?;
         const cell = list_cell.cell;
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
-        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint.data);
     }
     {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 6, .y = 0 } }).?;
@@ -8552,8 +8705,9 @@ test "Screen: resize more cols with wide spacer head multiple lines" {
 test "Screen: resize more cols requiring a wide spacer head" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 2, .rows = 2, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 2, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
     const str = "xx😀";
     try s.testWriteString(str);
@@ -8591,7 +8745,7 @@ test "Screen: resize more cols requiring a wide spacer head" {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 0, .y = 1 } }).?;
         const cell = list_cell.cell;
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
-        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '😀'), cell.content.codepoint.data);
     }
     {
         const list_cell = s.pages.getCell(.{ .screen = .{ .x = 1, .y = 1 } }).?;
@@ -8603,8 +8757,9 @@ test "Screen: resize more cols requiring a wide spacer head" {
 test "Screen: resize more cols with cursor at prompt" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
 
     // zig fmt: off
@@ -8643,8 +8798,9 @@ test "Screen: resize more cols with cursor at prompt" {
 test "Screen: resize more cols with cursor not at prompt" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
 
     // zig fmt: off
@@ -8684,8 +8840,9 @@ test "Screen: resize more cols with cursor not at prompt" {
 test "Screen: resize with prompt_redraw last clears only one line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 4, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 4, .max_scrollback = 5 });
     defer s.deinit();
 
     // zig fmt: off
@@ -8723,8 +8880,9 @@ test "Screen: resize with prompt_redraw last clears only one line" {
 test "Screen: resize with prompt_redraw last multiline prompt clears only last line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 5 });
     defer s.deinit();
 
     // Create a 3-line prompt: 1 initial + 2 continuation lines
@@ -8763,8 +8921,9 @@ test "Screen: resize with prompt_redraw last multiline prompt clears only last l
 test "Screen: select untracked" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("ABC  DEF\n 123\n456");
 
@@ -8783,8 +8942,9 @@ test "Screen: select untracked" {
 test "Screen: select replaces existing pins" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("ABC  DEF\n 123\n456");
 
@@ -8809,8 +8969,9 @@ test "Screen: select replaces existing pins" {
 test "Screen: reselecting tracked selection preserves its pins" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 2, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
 
     try s.select(Selection.init(
@@ -8826,8 +8987,9 @@ test "Screen: reselecting tracked selection preserves its pins" {
 test "Screen: selectAll" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
     {
@@ -8862,8 +9024,9 @@ test "Screen: selectAll" {
 test "Screen: selectLine" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("ABC  DEF\n 123\n456");
 
@@ -8943,8 +9106,9 @@ test "Screen: selectLine" {
 test "Screen: selectLine across soft-wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString(" 12 34012   \n 123");
 
@@ -8969,8 +9133,9 @@ test "Screen: selectLine across soft-wrap" {
 test "Screen: selectLine across full soft-wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1ABCD2EFGH\n3IJKL");
 
@@ -8994,8 +9159,9 @@ test "Screen: selectLine across full soft-wrap" {
 test "Screen: selectLine across soft-wrap ignores blank lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString(" 12 34012             \n 123");
 
@@ -9054,8 +9220,9 @@ test "Screen: selectLine across soft-wrap ignores blank lines" {
 test "Screen: selectLine disabled whitespace trimming" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString(" 12 34012   \n 123");
 
@@ -9103,8 +9270,9 @@ test "Screen: selectLine disabled whitespace trimming" {
 test "Screen: selectLine with scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 2, .rows = 3, .max_scrollback = 5 });
+    var s = try init(io, alloc, .{ .cols = 2, .rows = 3, .max_scrollback = 5 });
     defer s.deinit();
     try s.testWriteString("1A\n2B\n3C\n4D\n5E");
 
@@ -9147,8 +9315,9 @@ test "Screen: selectLine with scrollback" {
 test "Screen: selectLine semantic prompt boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("ABCDE\n");
     s.cursorSetSemanticContent(.{ .prompt = .initial });
@@ -9197,8 +9366,9 @@ test "Screen: selectLine semantic prompt boundary" {
 test "Screen: selectLine semantic prompt to input boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Write prompt followed by user input on same row: "$>command"
@@ -9246,8 +9416,9 @@ test "Screen: selectLine semantic prompt to input boundary" {
 test "Screen: selectLine semantic input to output boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Row 0: user input
@@ -9291,8 +9462,9 @@ test "Screen: selectLine semantic input to output boundary" {
 test "Screen: selectLine semantic mid-row boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Single row with output then prompt then input: "out$>cmd"
@@ -9359,8 +9531,9 @@ test "Screen: selectLine semantic mid-row boundary" {
 test "Screen: selectLine semantic boundary soft-wrap with mid-row transition" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Row 0: prompt "$ " + input "cmd" (soft-wraps)
@@ -9428,8 +9601,9 @@ test "Screen: selectLine semantic boundary soft-wrap with mid-row transition" {
 test "Screen: selectLine semantic boundary disabled" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Write prompt followed by input
@@ -9460,8 +9634,9 @@ test "Screen: selectLine semantic boundary disabled" {
 test "Screen: selectLine semantic boundary first cell of row" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Row 0: input that soft-wraps
@@ -9516,8 +9691,9 @@ test "Screen: selectLine semantic boundary first cell of row" {
 test "Screen: selectLine semantic boundary across mixed-width pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 4, .rows = 2, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 4, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
 
     s.cursorSetSemanticContent(.{ .input = .clear_explicit });
@@ -9547,8 +9723,9 @@ test "Screen: selectLine semantic boundary across mixed-width pages" {
 test "Screen: selectLine semantic all same content" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // All prompt content that soft-wraps
@@ -9581,15 +9758,19 @@ test "Screen: selectLine semantic all same content" {
 test "Screen: selectWord" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("ABC  DEF\n 123\n456");
 
     // Default boundary codepoints for word selection
     const boundary_codepoints = &[_]u21{
-        0,   ' ', '\t', '\'', '"', '│', '`', '|', ':', ';',
-        ',', '(', ')',  '[',  ']', '{',   '}', '<', '>', '$',
+        0,   ' ', '\t', '\'', '"',
+        '│',
+        '`', '|', ':',  ';',  ',',
+        '(', ')', '[',  ']',  '{',
+        '}', '<', '>',  '$',
     };
 
     // Outside of active area
@@ -9702,15 +9883,19 @@ test "Screen: selectWord" {
 test "Screen: selectWord across soft-wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString(" 1234012\n 123");
 
     // Default boundary codepoints for word selection
     const boundary_codepoints = &[_]u21{
-        0,   ' ', '\t', '\'', '"', '│', '`', '|', ':', ';',
-        ',', '(', ')',  '[',  ']', '{',   '}', '<', '>', '$',
+        0,   ' ', '\t', '\'', '"',
+        '│',
+        '`', '|', ':',  ';',  ',',
+        '(', ')', '[',  ']',  '{',
+        '}', '<', '>',  '$',
     };
 
     {
@@ -9774,15 +9959,19 @@ test "Screen: selectWord across soft-wrap" {
 test "Screen: selectWord whitespace across soft-wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("1       1\n 123");
 
     // Default boundary codepoints for word selection
     const boundary_codepoints = &[_]u21{
-        0,   ' ', '\t', '\'', '"', '│', '`', '|', ':', ';',
-        ',', '(', ')',  '[',  ']', '{',   '}', '<', '>', '$',
+        0,   ' ', '\t', '\'', '"',
+        '│',
+        '`', '|', ':',  ';',  ',',
+        '(', ')', '[',  ']',  '{',
+        '}', '<', '>',  '$',
     };
 
     // Going forward
@@ -9840,11 +10029,15 @@ test "Screen: selectWord whitespace across soft-wrap" {
 test "Screen: selectWord with character boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // Default boundary codepoints for word selection
     const boundary_codepoints = &[_]u21{
-        0,   ' ', '\t', '\'', '"', '│', '`', '|', ':', ';',
-        ',', '(', ')',  '[',  ']', '{',   '}', '<', '>', '$',
+        0,   ' ', '\t', '\'', '"',
+        '│',
+        '`', '|', ':',  ';',  ',',
+        '(', ')', '[',  ']',  '{',
+        '}', '<', '>',  '$',
     };
 
     const cases = [_][]const u8{
@@ -9868,7 +10061,7 @@ test "Screen: selectWord with character boundary" {
     };
 
     for (cases) |case| {
-        var s = try init(alloc, .{ .cols = 20, .rows = 10, .max_scrollback = 0 });
+        var s = try init(io, alloc, .{ .cols = 20, .rows = 10, .max_scrollback = 0 });
         defer s.deinit();
         try s.testWriteString(case);
 
@@ -9947,8 +10140,9 @@ test "Screen: selectWord with character boundary" {
 test "Screen: selectOutput" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 15, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 15, .max_scrollback = 0 });
     defer s.deinit();
 
     // Build content with cell-level semantic content:
@@ -10043,8 +10237,9 @@ test "Screen: selectOutput" {
 test "Screen: selectionString basic" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -10068,8 +10263,9 @@ test "Screen: selectionString basic" {
 test "Screen: selectionString start outside of written area" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -10093,8 +10289,9 @@ test "Screen: selectionString start outside of written area" {
 test "Screen: selectionString end outside of written area" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -10118,8 +10315,9 @@ test "Screen: selectionString end outside of written area" {
 test "Screen: selectionString trim space" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1AB  \n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -10155,8 +10353,9 @@ test "Screen: selectionString trim space" {
 test "Screen: selectionString trim empty line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1AB  \n\n2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -10192,8 +10391,9 @@ test "Screen: selectionString trim empty line" {
 test "Screen: selectionString soft wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH3IJKL";
     try s.testWriteString(str);
@@ -10217,8 +10417,9 @@ test "Screen: selectionString soft wrap" {
 test "Screen: selectionString wide char" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1A⚡";
     try s.testWriteString(str);
@@ -10272,8 +10473,9 @@ test "Screen: selectionString wide char" {
 test "Screen: selectionString wide char with header" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 3, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABC⚡";
     try s.testWriteString(str);
@@ -10298,8 +10500,9 @@ test "Screen: selectionString wide char with header" {
 test "Screen: selectionString empty with soft wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 2, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 2, .max_scrollback = 0 });
     defer s.deinit();
 
     // Let me describe the situation that caused this because this
@@ -10331,8 +10534,9 @@ test "Screen: selectionString empty with soft wrap" {
 test "Screen: selectionString with zero width joiner" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 1, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 1, .max_scrollback = 0 });
     defer s.deinit();
     const str = "👨‍"; // this has a ZWJ
     try s.testWriteString(str);
@@ -10341,7 +10545,7 @@ test "Screen: selectionString with zero width joiner" {
     {
         const pin = s.pages.pin(.{ .screen = .{ .y = 0, .x = 0 } }).?;
         const cell = pin.rowAndCell().cell;
-        try testing.expectEqual(@as(u21, 0x1F468), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F468), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         const cps = pin.node.page().lookupGrapheme(cell).?;
         try testing.expectEqual(@as(usize, 1), cps.len);
@@ -10367,8 +10571,9 @@ test "Screen: selectionString with zero width joiner" {
 test "Screen: selectionString, rectangle, basic" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 30, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 30, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     const str =
         \\Lorem ipsum dolor
@@ -10400,8 +10605,9 @@ test "Screen: selectionString, rectangle, basic" {
 test "Screen: selectionString, rectangle, w/EOL" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 30, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 30, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     const str =
         \\Lorem ipsum dolor
@@ -10435,8 +10641,9 @@ test "Screen: selectionString, rectangle, w/EOL" {
 test "Screen: selectionString, rectangle, more complex w/breaks" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 30, .rows = 8, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 30, .rows = 8, .max_scrollback = 0 });
     defer s.deinit();
     const str =
         \\Lorem ipsum dolor
@@ -10474,8 +10681,9 @@ test "Screen: selectionString, rectangle, more complex w/breaks" {
 test "Screen: selectionString multi-page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 2048 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 2048 });
     defer s.deinit();
 
     const first_page_size = s.pages.pages.first.?.capacity().rows;
@@ -10508,8 +10716,9 @@ test "Screen: selectionString multi-page" {
 test "Screen: lineIterator" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD\n2EFGH";
     try s.testWriteString(str);
@@ -10539,8 +10748,9 @@ test "Screen: lineIterator" {
 test "Screen: lineIterator soft wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH\n3ABCD";
     try s.testWriteString(str);
@@ -10571,8 +10781,9 @@ test "Screen: lineIterator soft wrap" {
 test "Screen: hyperlink start/end" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     try testing.expect(s.cursor.hyperlink_id == 0);
     {
@@ -10598,8 +10809,9 @@ test "Screen: hyperlink start/end" {
 test "Screen: hyperlink accepts its current values" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     try s.startHyperlink("http://example.com", "current");
@@ -10613,8 +10825,9 @@ test "Screen: hyperlink accepts its current values" {
 test "Screen: implicit hyperlink ID wraps" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     s.cursor.hyperlink_implicit_id = std.math.maxInt(size.OffsetInt);
@@ -10650,8 +10863,9 @@ test "Screen: implicit hyperlink ID wraps" {
 test "Screen: hyperlink reuse" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     try testing.expect(s.cursor.hyperlink_id == 0);
@@ -10684,12 +10898,13 @@ test "Screen: hyperlink reuse" {
 test "Screen: hyperlink cursor state on resize" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // This test depends on underlying PageList implementation so
     // it may be invalid one day. It's here to document/verify the
     // current behavior.
 
-    var s = try init(alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 5, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
 
     // Start a hyperlink
@@ -10719,8 +10934,9 @@ test "Screen: hyperlink cursor state on resize" {
 test "Screen: cursorSetHyperlink OOM + URI too large for string alloc" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
 
     // Start a hyperlink with a URI that just barely fits in the string alloc.
@@ -10753,8 +10969,9 @@ test "Screen: cursorSetHyperlink OOM + URI too large for string alloc" {
 test "Screen: increaseCapacity cursor style ref count preserved" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 5,
         .rows = 5,
         .max_scrollback = 0,
@@ -10808,8 +11025,9 @@ test "Screen: increaseCapacity cursor style ref count preserved" {
 test "Screen: increaseCapacity cursor hyperlink ref count preserved" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 5,
         .rows = 5,
         .max_scrollback = 0,
@@ -10851,8 +11069,9 @@ test "Screen: increaseCapacity cursor hyperlink ref count preserved" {
 test "Screen: increaseCapacity cursor with both style and hyperlink preserved" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 5,
         .rows = 5,
         .max_scrollback = 0,
@@ -10916,8 +11135,9 @@ test "Screen: increaseCapacity non-cursor page returns early" {
     // extra cursor accounting (style/hyperlink re-adding).
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 80,
         .rows = 24,
         .max_scrollback = 10000,
@@ -11001,9 +11221,10 @@ test "Screen: cursorDown to page with insufficient capacity" {
 
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // Small screen to make page boundary crossing easy to set up
-    var s = try init(alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 3, .max_scrollback = 1 });
     defer s.deinit();
 
     // Scroll down enough to create a second page
@@ -11070,9 +11291,10 @@ test "Screen setAttribute increases capacity when style map is full" {
     // returns OutOfSpace, manualStyleUpdate will split the page instead.
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // Use a small screen with multiple rows
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 10 });
     defer s.deinit();
 
     // Write content to multiple rows
@@ -11119,8 +11341,9 @@ test "Screen setAttribute increases capacity when style map is full" {
 test "Screen setAttribute splits page on OutOfSpace at max styles" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{
+    var s = try init(io, alloc, .{
         .cols = 10,
         .rows = 10,
         .max_scrollback = 0,
@@ -11190,7 +11413,8 @@ test "selectionString map allocation failure cleanup" {
     // the StringMap, we don't leak the already-allocated map.string.
     const testing = std.testing;
     const alloc = testing.allocator;
-    var s = try Screen.init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    const io = testing.io;
+    var s = try Screen.init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     try s.testWriteString("hello");
@@ -11219,8 +11443,9 @@ test "selectionString map allocation failure cleanup" {
 test "Screen: promptClickMove line right basic" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11246,8 +11471,9 @@ test "Screen: promptClickMove line right basic" {
 test "Screen: promptClickMove line right cursor not on input" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11273,8 +11499,9 @@ test "Screen: promptClickMove line right cursor not on input" {
 test "Screen: promptClickMove line right click on same position" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11299,8 +11526,9 @@ test "Screen: promptClickMove line right click on same position" {
 test "Screen: promptClickMove line right skips non-input cells" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11331,8 +11559,9 @@ test "Screen: promptClickMove line right skips non-input cells" {
 test "Screen: promptClickMove line right soft-wrapped line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11369,8 +11598,9 @@ test "Screen: promptClickMove line right soft-wrapped line" {
 test "Screen: promptClickMove disabled when click is none" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Click mode is .none by default (disabled)
@@ -11395,8 +11625,9 @@ test "Screen: promptClickMove disabled when click is none" {
 test "Screen: promptClickMove line right stops at hard wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11427,8 +11658,9 @@ test "Screen: promptClickMove line right stops at hard wrap" {
 test "Screen: promptClickMove line right stops at non-continuation row" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11474,8 +11706,9 @@ test "Screen: promptClickMove line right stops at non-continuation row" {
 test "Screen: promptClickMove line left basic" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11501,8 +11734,9 @@ test "Screen: promptClickMove line left basic" {
 test "Screen: promptClickMove line left skips non-input cells" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11533,8 +11767,9 @@ test "Screen: promptClickMove line left skips non-input cells" {
 test "Screen: promptClickMove line left soft-wrapped line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11571,8 +11806,9 @@ test "Screen: promptClickMove line left soft-wrapped line" {
 test "Screen: promptClickMove line left stops at hard wrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11603,11 +11839,12 @@ test "Screen: promptClickMove line left stops at hard wrap" {
 test "Screen: promptClickMove click right of input same line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // Set up: "> hello" where "> " is prompt and "hello" is input
     // Clicking to the right of the 'o' should move cursor past the input
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11633,8 +11870,9 @@ test "Screen: promptClickMove click right of input same line" {
 test "Screen: promptClickMove click right of input cursor at end" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11659,8 +11897,9 @@ test "Screen: promptClickMove click right of input cursor at end" {
 test "Screen: promptClickMove click right of input on lower line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11688,8 +11927,9 @@ test "Screen: promptClickMove click right of input on lower line" {
 test "Screen: promptClickMove click right of input cursor at end lower line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
@@ -11713,8 +11953,9 @@ test "Screen: promptClickMove click right of input cursor at end lower line" {
 test "Screen: promptClickMove click right of input cursor on last char" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try init(alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
+    var s = try init(io, alloc, .{ .cols = 20, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     // Enable line click mode
diff --git a/src/terminal/ScreenSet.zig b/src/terminal/ScreenSet.zig
index 4d3689e3b..64e95e70c 100644
--- a/src/terminal/ScreenSet.zig
+++ b/src/terminal/ScreenSet.zig
@@ -36,13 +36,14 @@ all: std.EnumMap(Key, *Screen),
 generations: std.EnumMap(Key, usize),
 
 pub fn init(
+    io: std.Io,
     alloc: Allocator,
     opts: Screen.Options,
 ) Allocator.Error!ScreenSet {
     // We need to initialize our initial primary screen
     const screen = try alloc.create(Screen);
     errdefer alloc.destroy(screen);
-    screen.* = try .init(alloc, opts);
+    screen.* = try .init(io, alloc, opts);
     return .{
         .active_key = .primary,
         .active = screen,
@@ -73,6 +74,7 @@ pub fn generation(self: *const ScreenSet, key: Key) usize {
 /// Get the screen for the given key, initializing it if necessary.
 pub fn getInit(
     self: *ScreenSet,
+    io: std.Io,
     alloc: Allocator,
     key: Key,
     opts: Screen.Options,
@@ -80,7 +82,7 @@ pub fn getInit(
     if (self.get(key)) |screen| return screen;
     const screen = try alloc.create(Screen);
     errdefer alloc.destroy(screen);
-    screen.* = try .init(alloc, opts);
+    screen.* = try .init(io, alloc, opts);
     self.all.put(key, screen);
     return screen;
 }
@@ -108,14 +110,15 @@ pub fn switchTo(self: *ScreenSet, key: Key) void {
 
 test ScreenSet {
     const alloc = testing.allocator;
-    var set: ScreenSet = try .init(alloc, .default);
+    const io = testing.io;
+    var set: ScreenSet = try .init(io, alloc, .default);
     defer set.deinit(alloc);
     try testing.expectEqual(.primary, set.active_key);
     try testing.expectEqual(@as(usize, 0), set.generation(.primary));
     try testing.expectEqual(@as(usize, 0), set.generation(.alternate));
 
     // Initialize a secondary screen
-    _ = try set.getInit(alloc, .alternate, .default);
+    _ = try set.getInit(io, alloc, .alternate, .default);
     try testing.expectEqual(@as(usize, 0), set.generation(.alternate));
 
     set.switchTo(.alternate);
@@ -124,7 +127,8 @@ test ScreenSet {
 
 test "ScreenSet generations" {
     const alloc = testing.allocator;
-    var set: ScreenSet = try .init(alloc, .default);
+    const io = testing.io;
+    var set: ScreenSet = try .init(io, alloc, .default);
     defer set.deinit(alloc);
 
     try testing.expectEqual(@as(usize, 0), set.generation(.primary));
@@ -135,7 +139,7 @@ test "ScreenSet generations" {
     try testing.expectEqual(@as(usize, 0), set.generation(.alternate));
 
     // Initializing a screen doesn't change the generation.
-    _ = try set.getInit(alloc, .alternate, .default);
+    _ = try set.getInit(io, alloc, .alternate, .default);
     try testing.expectEqual(@as(usize, 0), set.generation(.alternate));
 
     const alternate_generation = set.generation(.alternate);
@@ -144,7 +148,7 @@ test "ScreenSet generations" {
 
     // Reinitializing keeps the generation from the last removal, so stale
     // handles can distinguish the new screen from the destroyed screen.
-    _ = try set.getInit(alloc, .alternate, .default);
+    _ = try set.getInit(io, alloc, .alternate, .default);
     try testing.expectEqual(alternate_generation +% 1, set.generation(.alternate));
     try testing.expectEqual(@as(usize, 0), set.generation(.primary));
 }
diff --git a/src/terminal/Selection.zig b/src/terminal/Selection.zig
index be6854e5f..b85e56254 100644
--- a/src/terminal/Selection.zig
+++ b/src/terminal/Selection.zig
@@ -512,7 +512,7 @@ pub fn adjust(
 
 test "Selection: adjust right" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A1234\nB5678\nC1234\nD5678");
 
@@ -579,7 +579,7 @@ test "Selection: adjust right" {
 
 test "Selection: adjust left" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A1234\nB5678\nC1234\nD5678");
 
@@ -628,7 +628,7 @@ test "Selection: adjust left" {
 
 test "Selection: adjust left skips blanks" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A1234\nB5678\nC12\nD56");
 
@@ -677,7 +677,7 @@ test "Selection: adjust left skips blanks" {
 
 test "Selection: adjust up" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A\nB\nC\nD\nE");
 
@@ -724,7 +724,7 @@ test "Selection: adjust up" {
 
 test "Selection: adjust down" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A\nB\nC\nD\nE");
 
@@ -771,7 +771,7 @@ test "Selection: adjust down" {
 
 test "Selection: adjust down with not full screen" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A\nB\nC");
 
@@ -799,7 +799,7 @@ test "Selection: adjust down with not full screen" {
 
 test "Selection: adjust home" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A\nB\nC");
 
@@ -827,7 +827,7 @@ test "Selection: adjust home" {
 
 test "Selection: adjust end with not full screen" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A\nB\nC");
 
@@ -855,7 +855,7 @@ test "Selection: adjust end with not full screen" {
 
 test "Selection: adjust beginning of line" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 8, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 8, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A12 B34\nC12 D34");
 
@@ -925,7 +925,7 @@ test "Selection: adjust beginning of line" {
 
 test "Selection: adjust end of line" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 8, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 8, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("A12 B34\nC12 D34");
 
@@ -994,8 +994,9 @@ test "Selection: adjust end of line" {
 test "Selection: order, standard" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 100, .rows = 100, .max_scrollback = 1 });
+    var s = try Screen.init(io, alloc, .{ .cols = 100, .rows = 100, .max_scrollback = 1 });
     defer s.deinit();
 
     {
@@ -1057,7 +1058,7 @@ test "Selection: order, standard" {
 
 test "Selection: rectangle corners clamp across mixed-width pages" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{
+    var s = try Screen.init(testing.io, testing.allocator, .{
         .cols = 4,
         .rows = 2,
         .max_scrollback = 0,
@@ -1084,8 +1085,9 @@ test "Selection: rectangle corners clamp across mixed-width pages" {
 test "Selection: order, rectangle" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 100, .rows = 100, .max_scrollback = 1 });
+    var s = try Screen.init(io, alloc, .{ .cols = 100, .rows = 100, .max_scrollback = 1 });
     defer s.deinit();
 
     // Conventions:
@@ -1197,7 +1199,7 @@ test "Selection: order, rectangle" {
 test "topLeft" {
     const testing = std.testing;
 
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     {
         // forward
@@ -1260,7 +1262,7 @@ test "topLeft" {
 test "bottomRight" {
     const testing = std.testing;
 
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     {
         // forward
@@ -1323,7 +1325,7 @@ test "bottomRight" {
 test "ordered" {
     const testing = std.testing;
 
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     {
         // forward
@@ -1404,7 +1406,7 @@ test "ordered" {
 test "Selection: contains" {
     const testing = std.testing;
 
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10, .max_scrollback = 0 });
     defer s.deinit();
     {
         const sel = Selection.init(
@@ -1450,7 +1452,7 @@ test "Selection: contains" {
 test "Selection: contains, rectangle" {
     const testing = std.testing;
 
-    var s = try Screen.init(testing.allocator, .{ .cols = 15, .rows = 15, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 15, .rows = 15, .max_scrollback = 0 });
     defer s.deinit();
     {
         const sel = Selection.init(
@@ -1512,7 +1514,7 @@ test "Selection: contains, rectangle" {
 
 test "Selection: containedRow" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var s = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
 
     {
@@ -1632,7 +1634,7 @@ test "Selection: containedRow" {
 
 test "Selection: containedRow clamps mixed-width pages" {
     const testing = std.testing;
-    var s = try Screen.init(testing.allocator, .{
+    var s = try Screen.init(testing.io, testing.allocator, .{
         .cols = 4,
         .rows = 3,
         .max_scrollback = 0,
diff --git a/src/terminal/SelectionGesture.zig b/src/terminal/SelectionGesture.zig
index 2be1e8aa3..ddcb05be4 100644
--- a/src/terminal/SelectionGesture.zig
+++ b/src/terminal/SelectionGesture.zig
@@ -83,13 +83,6 @@ const point = @import("point.zig");
 const freestanding_wasm = builtin.target.cpu.arch == .wasm32 and
     builtin.target.os.tag == .freestanding;
 
-/// Monotonic timestamp type for click-repeat detection.
-///
-/// Freestanding wasm cannot reference std.time.Instant because Zig's stdlib
-/// Instant type depends on POSIX timespec for that target, so represent the C
-/// API nanosecond timestamp directly as a u64 there.
-pub const Time = if (freestanding_wasm) u64 else std.time.Instant;
-
 /// The tracked pin of the initial left click along with the screen
 /// that the pin is part of.
 left_click_pin: ?*Pin,
@@ -100,7 +93,7 @@ left_click_screen_generation: usize,
 /// The left click time was the last time the left click was done, if the
 /// caller could provide one. If this is null then we only support single clicks.
 left_click_count: u3,
-left_click_time: ?Time,
+left_click_time: ?std.Io.Timestamp,
 
 /// The selection behavior chosen for the active left-click gesture.
 left_click_behavior: Behavior,
@@ -232,7 +225,7 @@ pub const Press = struct {
     /// backwards timestamps reset the repeat sequence.
     /// This can be null if you're on a system that doesn't support
     /// time for some reason. In that case, we only support single clicks.
-    time: ?Time,
+    time: ?std.Io.Timestamp,
 
     /// The cell where the click was.
     ///
@@ -666,14 +659,11 @@ fn pressRepeat(
     self.left_click_behavior = p.behaviors[self.left_click_count - 1];
 }
 
-fn timeSince(time: Time, prev_time: Time) ?u64 {
-    if (comptime freestanding_wasm) {
-        if (time < prev_time) return null;
-        return time - prev_time;
-    }
+fn timeSince(time: std.Io.Timestamp, prev_time: std.Io.Timestamp) ?u64 {
+    const delta = prev_time.durationTo(time).toNanoseconds();
+    if (delta < 0) return null;
 
-    if (time.order(prev_time) == .lt) return null;
-    return time.since(prev_time);
+    return @as(u64, @intCast(@min(delta, std.math.maxInt(u64))));
 }
 
 /// Convert a caller-provided floating-point position to a pixel coordinate.
@@ -947,7 +937,7 @@ fn untrackPin(self: *SelectionGesture, t: *Terminal) void {
     screen.pages.untrackPin(pin);
 }
 
-fn testPress(t: *Terminal, x: u16, y: u32, time: ?std.time.Instant) Press {
+fn testPress(t: *Terminal, x: u16, y: u32, time: ?std.Io.Timestamp) Press {
     return .{
         .time = time,
         .pin = t.screens.active.pages.pin(.{ .active = .{
@@ -962,16 +952,6 @@ fn testPress(t: *Terminal, x: u16, y: u32, time: ?std.time.Instant) Press {
     };
 }
 
-fn testInstant(ns: u64) std.time.Instant {
-    return switch (builtin.os.tag) {
-        .windows, .uefi, .wasi => .{ .timestamp = ns },
-        else => .{ .timestamp = .{
-            .sec = @intCast(ns / std.time.ns_per_s),
-            .nsec = @intCast(ns % std.time.ns_per_s),
-        } },
-    };
-}
-
 fn testDrag(t: *Terminal, x: u16, y: u32, xpos: f64, ypos: f64) Drag {
     return .{
         .pin = t.screens.active.pages.pin(.{ .active = .{
@@ -1049,7 +1029,7 @@ fn testDragSelection(
         .padding_left = 5,
         .screen_height = 110,
     };
-    var screen = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var screen = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer screen.deinit();
 
     const click_pin = screen.pages.pin(.{
@@ -1110,7 +1090,7 @@ fn testDragSelectionIsNull(
         .padding_left = 5,
         .screen_height = 110,
     };
-    var screen = try Screen.init(testing.allocator, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
+    var screen = try Screen.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5, .max_scrollback = 0 });
     defer screen.deinit();
 
     const click_pin = screen.pages.pin(.{
@@ -1430,13 +1410,13 @@ test "SelectionGesture rectangle drag selection logic" {
 }
 
 test "SelectionGesture press records initial click" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 1, 2, time));
 
     try testing.expectEqual(@as(u3, 1), gesture.left_click_count);
@@ -1447,14 +1427,14 @@ test "SelectionGesture press records initial click" {
 }
 
 test "SelectionGesture press returns standard click selections" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta\none two");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     var event = testPress(&t, 1, 0, time);
     event.word_boundary_codepoints = &.{ ' ' };
 
@@ -1474,14 +1454,14 @@ test "SelectionGesture press returns standard click selections" {
 }
 
 test "SelectionGesture press behaviors choose press and drag behavior" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta\none two\nthree four");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     var event = testPress(&t, 1, 0, time);
     event.behaviors = &.{ .cell, .line, .word };
     event.word_boundary_codepoints = &.{ ' ' };
@@ -1506,7 +1486,7 @@ test "SelectionGesture press behaviors choose press and drag behavior" {
 }
 
 test "SelectionGesture output behavior selects and drags semantic output" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 10, .rows = 6 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 10, .rows = 6 });
     defer t.deinit(testing.allocator);
 
     const screen = t.screens.active;
@@ -1522,7 +1502,7 @@ test "SelectionGesture output behavior selects and drags semantic output" {
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var event = testPress(&t, 1, 0, try std.time.Instant.now());
+    var event = testPress(&t, 1, 0, std.Io.Timestamp.now(testing.io, .awake));
     event.behaviors = &.{ .output, .word, .line };
 
     const press_selection = (try gesture.press(&t, event)).?;
@@ -1542,13 +1522,13 @@ test "SelectionGesture output behavior selects and drags semantic output" {
 }
 
 test "SelectionGesture drag returns selection and records autoscroll" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
 
@@ -1570,13 +1550,13 @@ test "SelectionGesture drag returns selection and records autoscroll" {
 }
 
 test "SelectionGesture drag clamps unrepresentable positions" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
 
@@ -1594,13 +1574,13 @@ test "SelectionGesture drag clamps unrepresentable positions" {
 }
 
 test "SelectionGesture drag saturates overflowing geometry" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
     var drag_event = testDrag(&t, 1, 1, 10, 50);
     drag_event.geometry.columns = std.math.maxInt(u32);
     drag_event.geometry.cell_width = std.math.maxInt(u32);
@@ -1608,13 +1588,13 @@ test "SelectionGesture drag saturates overflowing geometry" {
 }
 
 test "SelectionGesture drag rejects empty geometry" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
     var drag_event = testDrag(&t, 1, 1, 10, 50);
     drag_event.geometry.columns = 0;
     drag_event.geometry.cell_width = 0;
@@ -1622,13 +1602,13 @@ test "SelectionGesture drag rejects empty geometry" {
 }
 
 test "SelectionGesture release clears autoscroll and records drag" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
     try testing.expectEqual(false, gesture.left_click_dragged);
 
     _ = gesture.drag(&t, testDrag(&t, 1, 1, 10, 1));
@@ -1643,16 +1623,16 @@ test "SelectionGesture release clears autoscroll and records drag" {
 }
 
 test "SelectionGesture release with invalidated click records drag" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
     try testing.expectEqual(false, gesture.left_click_dragged);
 
-    _ = try t.screens.getInit(testing.allocator, .alternate, .{
+    _ = try t.screens.getInit(testing.io, testing.allocator, .alternate, .{
         .cols = t.cols,
         .rows = t.rows,
     });
@@ -1664,13 +1644,13 @@ test "SelectionGesture release with invalidated click records drag" {
 }
 
 test "SelectionGesture same-cell threshold selection records drag" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
     try testing.expectEqual(false, gesture.left_click_dragged);
@@ -1685,7 +1665,7 @@ test "SelectionGesture same-cell threshold selection records drag" {
 }
 
 test "SelectionGesture drag without press returns null" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
@@ -1696,13 +1676,13 @@ test "SelectionGesture drag without press returns null" {
 }
 
 test "SelectionGesture drag autoscroll edge boundaries" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
 
@@ -1720,13 +1700,13 @@ test "SelectionGesture drag autoscroll edge boundaries" {
 }
 
 test "SelectionGesture autoscroll tick scrolls and continues drag" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
 
@@ -1744,7 +1724,7 @@ test "SelectionGesture autoscroll tick scrolls and continues drag" {
 }
 
 test "SelectionGesture autoscroll tick resolves drag pin after scrolling" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 3, .max_scrollback = 10 });
     defer t.deinit(testing.allocator);
     try t.printString("1111\n2222\n3333\n4444\n5555");
     t.scrollViewport(.{ .delta = -2 });
@@ -1752,7 +1732,7 @@ test "SelectionGesture autoscroll tick resolves drag pin after scrolling" {
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
 
@@ -1773,20 +1753,20 @@ test "SelectionGesture autoscroll tick resolves drag pin after scrolling" {
 }
 
 test "SelectionGesture autoscroll tick stops with invalidated click" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
 
     _ = gesture.drag(&t, testDrag(&t, 2, 1, 20, 1));
     try testing.expectEqual(.up, gesture.left_drag_autoscroll);
 
-    _ = try t.screens.getInit(testing.allocator, .alternate, .{
+    _ = try t.screens.getInit(testing.io, testing.allocator, .alternate, .{
         .cols = t.cols,
         .rows = t.rows,
     });
@@ -1798,14 +1778,14 @@ test "SelectionGesture autoscroll tick stops with invalidated click" {
 }
 
 test "SelectionGesture deep press selects word and consumes drag" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    _ = try gesture.press(&t, testPress(&t, 1, 0, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 0, std.Io.Timestamp.now(testing.io, .awake)));
     _ = gesture.drag(&t, testDrag(&t, 1, 0, 10, 1));
     try testing.expectEqual(.up, gesture.left_drag_autoscroll);
 
@@ -1819,7 +1799,7 @@ test "SelectionGesture deep press selects word and consumes drag" {
         false,
     ), sel);
     try testing.expectEqual(@as(u3, 0), gesture.left_click_count);
-    try testing.expectEqual(@as(?std.time.Instant, null), gesture.left_click_time);
+    try testing.expectEqual(@as(?std.Io.Timestamp, null), gesture.left_click_time);
     try testing.expectEqual(true, gesture.left_click_dragged);
     try testing.expectEqual(.none, gesture.left_drag_autoscroll);
     try testing.expect(gesture.left_click_pin == null);
@@ -1830,20 +1810,20 @@ test "SelectionGesture deep press selects word and consumes drag" {
 }
 
 test "SelectionGesture drag with invalidated click returns null" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var press_event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var press_event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     press_event.xpos = 10;
     _ = try gesture.press(&t, press_event);
 
     _ = gesture.drag(&t, testDrag(&t, 2, 1, 20, 1));
     try testing.expectEqual(.up, gesture.left_drag_autoscroll);
 
-    _ = try t.screens.getInit(testing.allocator, .alternate, .{
+    _ = try t.screens.getInit(testing.io, testing.allocator, .alternate, .{
         .cols = t.cols,
         .rows = t.rows,
     });
@@ -1854,14 +1834,14 @@ test "SelectionGesture drag with invalidated click returns null" {
 }
 
 test "SelectionGesture double-click drag selects by word" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta gamma");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 1, 0, time));
     _ = try gesture.press(&t, testPress(&t, 1, 0, time));
 
@@ -1877,14 +1857,14 @@ test "SelectionGesture double-click drag selects by word" {
 }
 
 test "SelectionGesture double-click drag selects by word backwards" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta gamma");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 7, 0, time));
     _ = try gesture.press(&t, testPress(&t, 7, 0, time));
 
@@ -1900,14 +1880,14 @@ test "SelectionGesture double-click drag selects by word backwards" {
 }
 
 test "SelectionGesture double-click drag on empty cell selects nearest word" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 1, 0, time));
     _ = try gesture.press(&t, testPress(&t, 1, 0, time));
 
@@ -1923,14 +1903,14 @@ test "SelectionGesture double-click drag on empty cell selects nearest word" {
 }
 
 test "SelectionGesture triple-click drag selects by line" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta\none two\nthree four");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 1, 0, time));
     _ = try gesture.press(&t, testPress(&t, 1, 0, time));
     _ = try gesture.press(&t, testPress(&t, 1, 0, time));
@@ -1945,14 +1925,14 @@ test "SelectionGesture triple-click drag selects by line" {
 }
 
 test "SelectionGesture triple-click drag selects by line backwards" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 20, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 20, .rows = 5 });
     defer t.deinit(testing.allocator);
     try t.printString("alpha beta\none two\nthree four");
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 2, 2, time));
     _ = try gesture.press(&t, testPress(&t, 2, 2, time));
     _ = try gesture.press(&t, testPress(&t, 2, 2, time));
@@ -1967,13 +1947,13 @@ test "SelectionGesture triple-click drag selects by line backwards" {
 }
 
 test "SelectionGesture repeat increments click count" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 1, 1, time));
     _ = try gesture.press(&t, testPress(&t, 1, 1, time));
 
@@ -1981,54 +1961,54 @@ test "SelectionGesture repeat increments click count" {
 }
 
 test "SelectionGesture repeat clamps at triple click" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     for (0..4) |_| _ = try gesture.press(&t, testPress(&t, 1, 1, time));
 
     try testing.expectEqual(@as(u3, 3), gesture.left_click_count);
 }
 
 test "SelectionGesture null initial time stays single click" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
     _ = try gesture.press(&t, testPress(&t, 1, 1, null));
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
 
     try testing.expectEqual(@as(u3, 1), gesture.left_click_count);
     try testing.expect(gesture.left_click_time != null);
 }
 
 test "SelectionGesture null repeat time stays single click" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
     _ = try gesture.press(&t, testPress(&t, 1, 1, null));
 
     try testing.expectEqual(@as(u3, 1), gesture.left_click_count);
-    try testing.expectEqual(@as(?std.time.Instant, null), gesture.left_click_time);
+    try testing.expectEqual(@as(?std.Io.Timestamp, null), gesture.left_click_time);
 }
 
 test "SelectionGesture distant press resets click count" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, testPress(&t, 1, 1, time));
     _ = try gesture.press(&t, testPress(&t, 4, 1, time));
 
@@ -2037,51 +2017,52 @@ test "SelectionGesture distant press resets click count" {
 }
 
 test "SelectionGesture expired repeat resets click count" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    var event = testPress(&t, 1, 1, try std.time.Instant.now());
+    var event = testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake));
     event.repeat_interval = 0;
     _ = try gesture.press(&t, event);
 
-    std.Thread.sleep(std.time.ns_per_ms);
-    event.time = try std.time.Instant.now();
+    try std.Io.sleep(testing.io, std.Io.Duration.fromMilliseconds(1), .awake);
+    event.time = std.Io.Timestamp.now(testing.io, .awake);
     _ = try gesture.press(&t, event);
 
     try testing.expectEqual(@as(u3, 1), gesture.left_click_count);
 }
 
 test "SelectionGesture backwards repeat time resets click count" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const earlier = testInstant(std.time.ns_per_s);
-    const later = testInstant(2 * std.time.ns_per_s);
+    const now: std.Io.Timestamp = .now(testing.io, .awake);
+    const earlier = now.addDuration(.fromSeconds(1));
+    const later = now.addDuration(.fromSeconds(2));
     _ = try gesture.press(&t, testPress(&t, 1, 1, later));
     _ = try gesture.press(&t, testPress(&t, 1, 1, earlier));
 
     try testing.expectEqual(@as(u3, 1), gesture.left_click_count);
-    try testing.expectEqual(.eq, gesture.left_click_time.?.order(earlier));
+    try testing.expectEqualDeep(earlier, gesture.left_click_time.?);
 }
 
 test "SelectionGesture screen switch resets click count" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    const time = try std.time.Instant.now();
+    const time = std.Io.Timestamp.now(testing.io, .awake);
     const primary_tracked = t.screens.active.pages.countTrackedPins();
     _ = try gesture.press(&t, testPress(&t, 1, 1, time));
 
-    _ = try t.screens.getInit(testing.allocator, .alternate, .{
+    _ = try t.screens.getInit(testing.io, testing.allocator, .alternate, .{
         .cols = t.cols,
         .rows = t.rows,
     });
@@ -2094,34 +2075,34 @@ test "SelectionGesture screen switch resets click count" {
 }
 
 test "SelectionGesture removed screen resets without untracking stale pin" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     defer gesture.deinit(&t);
 
-    _ = try t.screens.getInit(testing.allocator, .alternate, .{
+    _ = try t.screens.getInit(testing.io, testing.allocator, .alternate, .{
         .cols = t.cols,
         .rows = t.rows,
     });
     t.screens.switchTo(.alternate);
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
 
     t.screens.switchTo(.primary);
     t.screens.remove(testing.allocator, .alternate);
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
 
     try testing.expectEqual(@as(u3, 1), gesture.left_click_count);
     try testing.expectEqual(.primary, gesture.left_click_screen);
 }
 
 test "SelectionGesture deinit untracks pin" {
-    var t = try Terminal.init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try Terminal.init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var gesture: SelectionGesture = .init;
     const tracked = t.screens.active.pages.countTrackedPins();
-    _ = try gesture.press(&t, testPress(&t, 1, 1, try std.time.Instant.now()));
+    _ = try gesture.press(&t, testPress(&t, 1, 1, std.Io.Timestamp.now(testing.io, .awake)));
     try testing.expectEqual(tracked + 1, t.screens.active.pages.countTrackedPins());
 
     gesture.deinit(&t);
diff --git a/src/terminal/StringMap.zig b/src/terminal/StringMap.zig
index 18dd7b19c..d5de87426 100644
--- a/src/terminal/StringMap.zig
+++ b/src/terminal/StringMap.zig
@@ -117,6 +117,7 @@ test "StringMap searchIterator" {
 
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // Initialize our regex
     try oni.testing.ensureInit();
@@ -130,7 +131,7 @@ test "StringMap searchIterator" {
     defer re.deinit();
 
     // Initialize our screen
-    var s = try Screen.init(alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 5, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     const str = "1ABCD2EFGH\n3IJKL";
     try s.testWriteString(str);
@@ -174,6 +175,7 @@ test "StringMap searchIterator URL detection" {
 
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
     const url = @import("../config/url.zig");
 
     // Initialize URL regex
@@ -188,7 +190,7 @@ test "StringMap searchIterator URL detection" {
     defer re.deinit();
 
     // Initialize our screen with text containing a URL
-    var s = try Screen.init(alloc, .{ .cols = 40, .rows = 5, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 40, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello https://example.com/path world");
 
@@ -235,6 +237,7 @@ test "StringMap searchIterator URL with click position" {
 
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
     const url = @import("../config/url.zig");
 
     // Initialize URL regex
@@ -249,7 +252,7 @@ test "StringMap searchIterator URL with click position" {
     defer re.deinit();
 
     // Initialize our screen with text containing a URL
-    var s = try Screen.init(alloc, .{ .cols = 40, .rows = 5, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 40, .rows = 5, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello https://example.com world");
 
diff --git a/src/terminal/Terminal.zig b/src/terminal/Terminal.zig
index bc5c9834a..52c066ebc 100644
--- a/src/terminal/Terminal.zig
+++ b/src/terminal/Terminal.zig
@@ -10,6 +10,7 @@ const assert = @import("../quirks.zig").inlineAssert;
 const tripwire = @import("../tripwire.zig");
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
+const simd = @import("../simd/main.zig");
 const unicode = @import("../unicode/main.zig");
 const uucode = @import("uucode");
 
@@ -289,13 +290,14 @@ pub const Options = struct {
 
 /// Initialize a new terminal.
 pub fn init(
+    io_impl: std.Io,
     alloc: Allocator,
     opts: Options,
 ) !Terminal {
     const cols = opts.cols;
     const rows = opts.rows;
 
-    var screen_set: ScreenSet = try .init(alloc, .{
+    var screen_set: ScreenSet = try .init(io_impl, alloc, .{
         .cols = cols,
         .rows = rows,
         .max_scrollback = opts.max_scrollback,
@@ -420,6 +422,11 @@ pub fn setDefaultCursorBlink(self: *Terminal, blink: ?bool) void {
     if (self.cursor.is_default) self.setCursorStyle(.default);
 }
 
+/// The I/O implementation we should use for this terminal.
+pub fn io(self: *Terminal) std.Io {
+    return self.screens.active.io;
+}
+
 /// The general allocator we should use for this terminal.
 pub fn gpa(self: *Terminal) Allocator {
     return self.screens.active.alloc;
@@ -624,6 +631,85 @@ inline fn printSliceEligible(cp: u32, comptime width: PrintSliceWidth) bool {
     });
 }
 
+/// Store a run of narrow codepoint cells built from a bit template:
+/// for each `idx` in `[from, to)`, `cells[idx]` is assigned the bits
+/// `template_bits | (cps[idx] << cp_shift)`.
+///
+/// The template is a complete Cell (content tag, style, wide state,
+/// etc. already baked in by the caller) whose codepoint content bits
+/// are zero. Since Cell is a packed struct(u64), OR-ing a codepoint
+/// into the content field's bit position yields a finished cell as a
+/// single integer, keeping the loop pure data movement: no per-cell
+/// field assignments and no branches.
+///
+/// This loop is manually vectorized: Zig 0.16 (LLVM 21) no longer
+/// auto-vectorizes the scalar form the way Zig 0.15 (LLVM 20) did.
+inline fn printSliceStoreRun(
+    cells: [*]Cell,
+    cps: [*]const u32,
+    from: usize,
+    to: usize,
+    template_bits: u64,
+) void {
+    // The bit position of the `content` field within the packed
+    // Cell. A codepoint occupies the low bits of `content`, so
+    // shifting a codepoint left by this amount places it exactly
+    // where `.content = .{ .codepoint = .{ .data = cp } }` would.
+    const cp_shift = @bitOffsetOf(Cell, "content");
+
+    // Since codepoints are OR'd into the content field rather than
+    // assigned, any nonzero content bits in the template would
+    // corrupt the stored codepoints.
+    const content_mask: u64 = comptime mask: {
+        const bits = @bitSizeOf(@FieldType(Cell, "content"));
+        break :mask ((1 << bits) - 1) << cp_shift;
+    };
+    assert(template_bits & content_mask == 0);
+
+    var idx = from;
+
+    // Vectorized bulk of the run.
+    if (simd.lanes(u64)) |lanes| {
+        // u64 due to backing integer of Cell
+        const V = @Vector(lanes, u64);
+
+        // The template and shift amount are loop-invariant, so
+        // broadcast them to every lane once up front.
+        const template: V = @splat(template_bits);
+        const shift: @Vector(
+            lanes,
+            std.math.Log2Int(u64),
+        ) = @splat(cp_shift);
+
+        while (idx + lanes <= to) : (idx += lanes) {
+            // Load `lanes` decoded codepoints...
+            const narrow: @Vector(lanes, u32) = cps[idx..][0..lanes].*;
+
+            // ...widen each u32 lane to the u64 cell size...
+            const wide: V = @intCast(narrow);
+
+            // ...shift each codepoint into the content field's bit
+            // position and merge with the template, producing
+            // `lanes` finished cells (coerced from vector to array
+            // so they can be bitcast for the store below)...
+            const bits: [lanes]u64 = template | (wide << shift);
+
+            // ...and store them contiguously. Cell is a packed
+            // struct(u64) so an array of u64 bit patterns has
+            // identical layout to an array of cells.
+            cells[idx..][0..lanes].* = @bitCast(bits);
+        }
+    }
+
+    // Scalar tail: the final `< lanes` cells of the run, or the
+    // entire run on targets without SIMD. Note `idx` carries over
+    // from the vector loop above. This is the same computation as
+    // the vector body, one cell at a time.
+    while (idx < to) : (idx += 1) {
+        cells[idx] = @bitCast(template_bits | (@as(u64, cps[idx]) << cp_shift));
+    }
+}
+
 /// The row-filling portion of the printSlice fast path, specialized by
 /// width class. The first codepoint must already be validated by the
 /// caller (printSliceFast).
@@ -665,19 +751,20 @@ fn printSliceFill(
         // Anything else (including eligible unicode) proceeds via
         // the scalar loop below.
         if (comptime width == .narrow) {
-            const lanes = 8;
-            const V = @Vector(lanes, u32);
-            const lo: V = @splat(0x10);
-            const hi: V = @splat(0xFF);
-            while (idx + lanes <= cps.len) {
-                const v: V = cps[idx..][0..lanes].*;
-                const in_range = (v >= lo) & (v <= hi);
-                if (!@reduce(.And, in_range)) {
-                    const bits: std.meta.Int(.unsigned, lanes) = @bitCast(in_range);
-                    idx += @ctz(~bits);
-                    break;
+            if (simd.lanes(u32)) |lanes| {
+                const V = @Vector(lanes, u32);
+                const lo: V = @splat(0x10);
+                const hi: V = @splat(0xFF);
+                while (idx + lanes <= cps.len) {
+                    const v: V = cps[idx..][0..lanes].*;
+                    const in_range = (v >= lo) & (v <= hi);
+                    if (!@reduce(.And, in_range)) {
+                        const bits: std.meta.Int(.unsigned, lanes) = @bitCast(in_range);
+                        idx += @ctz(~bits);
+                        break;
+                    }
+                    idx += lanes;
                 }
-                idx += lanes;
             }
         }
 
@@ -734,7 +821,7 @@ fn printSliceFill(
         const style_id = cursor.style_id;
         const template: Cell = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 0 },
+            .content = .{ .codepoint = .{ .data = 0 } },
             .style_id = style_id,
             .wide = .narrow,
             .protected = cursor.protected,
@@ -811,12 +898,38 @@ fn printSliceFill(
                 // We can only write whole (wide, spacer) pairs.
                 const pair_end = k + (simple - k) / 2 * 2;
                 var idx = k;
+
+                // Manually vectorized for the same reason as
+                // printSliceStoreRun: build a vector of wide cells,
+                // interleave with spacer tails, and store (wide,
+                // spacer) pairs several at a time.
+                if (simd.lanes(u64)) |lanes| {
+                    const pair_lanes = lanes / 2;
+                    const Vp = @Vector(pair_lanes, u64);
+                    const wide_v: Vp = @splat(wide_bits);
+                    const spacer_v: Vp = @splat(spacer_bits);
+                    const shift_v: @Vector(
+                        pair_lanes,
+                        std.math.Log2Int(u64),
+                    ) = @splat(cp_shift);
+                    while (idx + 2 * pair_lanes <= pair_end) : (idx += 2 * pair_lanes) {
+                        const narrow: @Vector(pair_lanes, u32) =
+                            cps[printed + idx / 2 ..][0..pair_lanes].*;
+                        const wides: Vp = wide_v | (@as(Vp, @intCast(narrow)) << shift_v);
+                        const inter: [2 * pair_lanes]u64 = std.simd.interlace(.{
+                            wides,
+                            spacer_v,
+                        });
+                        cells[idx..][0 .. 2 * pair_lanes].* = @bitCast(inter);
+                    }
+                }
                 while (idx < pair_end) : (idx += 2) {
                     cells[idx] = @bitCast(
                         wide_bits | (@as(u64, cps[printed + idx / 2]) << cp_shift),
                     );
                     cells[idx + 1] = @bitCast(spacer_bits);
                 }
+
                 // If the simple run ended mid-pair we stop at the pair
                 // boundary and handle the offending cell below.
                 k = pair_end;
@@ -826,11 +939,13 @@ fn printSliceFill(
                     simple = pair_end;
                 }
             } else {
-                for (k..simple) |idx| {
-                    cells[idx] = @bitCast(
-                        template_bits | (@as(u64, cps[printed + idx]) << cp_shift),
-                    );
-                }
+                printSliceStoreRun(
+                    cells,
+                    cps.ptr + printed,
+                    k,
+                    simple,
+                    template_bits,
+                );
                 k = simple;
             }
             if (k >= cell_count) break;
@@ -882,11 +997,13 @@ fn printSliceFill(
                     page.styles.useMultiple(page.memory, style_id, @intCast(n));
                 }
 
-                for (k..m) |idx| {
-                    cells[idx] = @bitCast(
-                        template_bits | (@as(u64, cps[printed + idx]) << cp_shift),
-                    );
-                }
+                printSliceStoreRun(
+                    cells,
+                    cps.ptr + printed,
+                    k,
+                    m,
+                    template_bits,
+                );
                 k = m;
                 continue :fill;
             }
@@ -1029,7 +1146,7 @@ pub fn print(self: *Terminal, c: u21) !void {
         // necessarily a grapheme break.
         if (prev.cell.codepoint() == 0) break :grapheme;
 
-        var previous_codepoint: u21 = prev.cell.content.codepoint;
+        var previous_codepoint: u21 = prev.cell.content.codepoint.data;
         const grapheme_break = brk: {
             var state: uucode.grapheme.BreakState = .default;
             if (prev.cell.hasGrapheme()) {
@@ -1076,13 +1193,13 @@ pub fn print(self: *Terminal, c: u21) !void {
                         const row_wrap = right_limit == self.cols;
                         if (row_wrap) self.screens.active.cursor.page_row.wrap = true;
 
-                        const prev_cp = prev.cell.content.codepoint;
+                        const prev_cp = prev.cell.content.codepoint.data;
                         if (prev.cell.hasGrapheme()) {
                             // This is like printCell but without clearing the
                             // grapheme data from the cell, so we can move it
                             // later.
                             prev.cell.wide = if (row_wrap) .spacer_head else .narrow;
-                            prev.cell.content.codepoint = 0;
+                            prev.cell.content.codepoint.data = 0;
 
                             try self.printWrap();
                             self.printCell(prev_cp, .wide);
@@ -1235,7 +1352,7 @@ pub fn print(self: *Terminal, c: u21) !void {
 
         // If this is a emoji variation selector, prev must be an emoji
         if (c == 0xFE0F or c == 0xFE0E) {
-            const prev_props = unicode.table.get(prev.content.codepoint);
+            const prev_props = unicode.table.get(prev.content.codepoint.data);
             const emoji = prev_props.grapheme_break == .extended_pictographic;
             if (!emoji) return;
         }
@@ -1448,7 +1565,7 @@ fn printCell(
     // Write
     cell.* = .{
         .content_tag = .codepoint,
-        .content = .{ .codepoint = c },
+        .content = .{ .codepoint = .{ .data = c } },
         .style_id = self.screens.active.cursor.style_id,
         .wide = wide,
         .protected = self.screens.active.cursor.protected,
@@ -2496,7 +2613,7 @@ fn rowWillBeShifted(
             page.clearGrapheme(wide_cell);
             page.updateRowGraphemeFlag(row);
         }
-        wide_cell.content.codepoint = 0;
+        wide_cell.content.codepoint = .{ .data = 0 };
         wide_cell.wide = .narrow;
         left_cell.wide = .narrow;
     }
@@ -2507,7 +2624,7 @@ fn rowWillBeShifted(
             page.clearGrapheme(right_cell);
             page.updateRowGraphemeFlag(row);
         }
-        right_cell.content.codepoint = 0;
+        right_cell.content.codepoint.data = 0;
         right_cell.wide = .narrow;
         tail_cell.wide = .narrow;
     }
@@ -3175,6 +3292,7 @@ pub fn eraseDisplay(
             if (comptime build_options.kitty_graphics) {
                 // Clear all Kitty graphics state for this screen
                 self.screens.active.kitty_images.delete(
+                    self.io(),
                     self.screens.active.alloc,
                     self,
                     .{ .all = true },
@@ -3232,6 +3350,7 @@ pub fn eraseDisplay(
             if (comptime build_options.kitty_graphics) {
                 // Clear all Kitty graphics state for this screen
                 self.screens.active.kitty_images.delete(
+                    self.io(),
                     self.screens.active.alloc,
                     self,
                     .{ .all = true },
@@ -3324,7 +3443,7 @@ pub fn decaln(self: *Terminal) !void {
         const cells = cells_multi[0..page.size.cols];
         @memset(cells, .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 'E' },
+            .content = .{ .codepoint = .{ .data = 'E' } },
             .style_id = self.screens.active.cursor.style_id,
 
             // DECALN does not respect protected state. Verified with xterm.
@@ -3362,10 +3481,11 @@ pub fn decaln(self: *Terminal) !void {
 /// undefined.
 pub fn kittyGraphics(
     self: *Terminal,
+    io_impl: std.Io,
     alloc: Allocator,
     cmd: *kitty.graphics.Command,
 ) ?kitty.graphics.Response {
-    return kitty.graphics.execute(alloc, self, cmd);
+    return kitty.graphics.execute(io_impl, alloc, self, cmd);
 }
 
 /// Execute a Glyph Protocol APC command against this terminal's per-session
@@ -3394,7 +3514,7 @@ pub fn setKittyGraphicsSizeLimit(
     var it = self.screens.all.iterator();
     while (it.next()) |entry| {
         const screen: *Screen = entry.value.*;
-        try screen.kitty_images.setLimit(alloc, screen, limit);
+        try screen.kitty_images.setLimit(self.io(), alloc, screen, limit);
     }
 }
 
@@ -3423,8 +3543,7 @@ pub fn setAttribute(self: *Terminal, attr: sgr.Attribute) !void {
 /// Boolean attributes are printed first, followed by foreground color, then
 /// background color. Each attribute is separated by a semicolon.
 pub fn printAttributes(self: *Terminal, buf: []u8) ![]const u8 {
-    var stream = std.io.fixedBufferStream(buf);
-    const writer = stream.writer();
+    var writer: std.Io.Writer = .fixed(buf);
 
     // The SGR response always starts with a 0. See https://vt100.net/docs/vt510-rm/DECRPSS
     try writer.writeByte('0');
@@ -3499,7 +3618,7 @@ pub fn printAttributes(self: *Terminal, buf: []u8) ![]const u8 {
         .rgb => |rgb| try writer.print(";48:2::{[r]}:{[g]}:{[b]}", rgb),
     }
 
-    return stream.getWritten();
+    return writer.buffered();
 }
 
 /// The modes for DECCOLM.
@@ -3697,18 +3816,23 @@ pub fn resize(
         // we just go back to the primary screen. Not great, but best
         // we can do.
         tw.check(.alternate_screen_init) catch break :alt;
-        const replacement = self.screens.getInit(alloc, .alternate, .{
-            .cols = opts.cols,
-            .rows = opts.rows,
-            .max_scrollback = 0,
-            .kitty_image_storage_limit = if (comptime build_options.kitty_graphics)
-                primary.kitty_images.total_limit
-            else
-                0,
-            .kitty_image_loading_limits = if (comptime build_options.kitty_graphics)
-                primary.kitty_images.image_limits
-            else {},
-        }) catch |init_err| {
+        const replacement = self.screens.getInit(
+            self.io(),
+            alloc,
+            .alternate,
+            .{
+                .cols = opts.cols,
+                .rows = opts.rows,
+                .max_scrollback = 0,
+                .kitty_image_storage_limit = if (comptime build_options.kitty_graphics)
+                    primary.kitty_images.total_limit
+                else
+                    0,
+                .kitty_image_loading_limits = if (comptime build_options.kitty_graphics)
+                    primary.kitty_images.image_limits
+                else {},
+            },
+        ) catch |init_err| {
             log.warn(
                 "alternate screen replacement failed, falling back to primary err={}",
                 .{init_err},
@@ -3749,7 +3873,8 @@ pub fn resize(
 
 test "Terminal: resize resets synchronized output" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.synchronized_output, true);
@@ -3759,7 +3884,8 @@ test "Terminal: resize resets synchronized output" {
 
 test "Terminal: resize rejects zero dimensions before mutation" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.width_px = 100;
@@ -3786,7 +3912,8 @@ test "Terminal: resize rejects zero dimensions before mutation" {
 
 test "Terminal: resize preserves pixel dimensions when omitted" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.width_px = 90;
@@ -3799,7 +3926,8 @@ test "Terminal: resize preserves pixel dimensions when omitted" {
 
 test "Terminal: resize updates pixels without changing cell dimensions" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.resize(alloc, .{
@@ -3814,7 +3942,8 @@ test "Terminal: resize updates pixels without changing cell dimensions" {
 
 test "Terminal: resize pixel dimensions saturate" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 3 });
     defer t.deinit(alloc);
 
     try t.resize(alloc, .{
@@ -3833,7 +3962,8 @@ test "Terminal: resize pixel dimensions saturate" {
 test "Terminal: resize preserves tabstops on allocation failure" {
     var failing = testing.FailingAllocator.init(testing.allocator, .{});
     const alloc = failing.allocator();
-    var t = try init(alloc, .{ .cols = 10, .rows = 1 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 1 });
     defer t.deinit(alloc);
 
     failing.fail_index = failing.alloc_index;
@@ -3848,6 +3978,7 @@ test "Terminal: resize preserves tabstops on allocation failure" {
 
 test "Terminal: resize failure paths preserve consistent state" {
     const alloc = testing.allocator;
+    const io_impl = testing.io;
 
     for ([_]resize_tw.FailPoint{
         .tabstops,
@@ -3857,7 +3988,7 @@ test "Terminal: resize failure paths preserve consistent state" {
         const tw = resize_tw;
         defer tw.end(.reset) catch unreachable;
 
-        var t = try init(alloc, .{ .cols = 10, .rows = 3 });
+        var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 3 });
         defer t.deinit(alloc);
 
         try t.printString("primary");
@@ -3984,10 +4115,11 @@ test "Terminal: resize failure paths preserve consistent state" {
 
 test "Terminal: alternate resize failure replaces active alternate screen" {
     const alloc = testing.allocator;
+    const io_impl = testing.io;
     const tw = resize_tw;
     defer tw.end(.reset) catch unreachable;
 
-    var t = try init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     _ = try t.switchScreen(.alternate);
@@ -4011,10 +4143,11 @@ test "Terminal: alternate resize failure replaces active alternate screen" {
 
 test "Terminal: alternate resize replacement failure falls back to primary" {
     const alloc = testing.allocator;
+    const io_impl = testing.io;
     const tw = resize_tw;
     defer tw.end(.reset) catch unreachable;
 
-    var t = try init(alloc, .{ .cols = 10, .rows = 3 });
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     _ = try t.switchScreen(.alternate);
@@ -4056,7 +4189,8 @@ pub fn getPwd(self: *const Terminal) ?[:0]const u8 {
 test "Terminal: setPwd preserves a sentinel on allocation failure" {
     var failing = testing.FailingAllocator.init(testing.allocator, .{});
     const alloc = failing.allocator();
-    var t = try init(alloc, .{ .cols = 5, .rows = 1 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 1 });
     defer t.deinit(alloc);
 
     try t.pwd.ensureTotalCapacityPrecise(alloc, 3);
@@ -4066,7 +4200,7 @@ test "Terminal: setPwd preserves a sentinel on allocation failure" {
 }
 
 test "Terminal: setPwd accepts its current value" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 1 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 1 });
     defer t.deinit(testing.allocator);
 
     try t.setPwd("file:///tmp");
@@ -4100,7 +4234,8 @@ pub fn getTitle(self: *const Terminal) ?[:0]const u8 {
 test "Terminal: setTitle preserves a sentinel on allocation failure" {
     var failing = testing.FailingAllocator.init(testing.allocator, .{});
     const alloc = failing.allocator();
-    var t = try init(alloc, .{ .cols = 5, .rows = 1 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 1 });
     defer t.deinit(alloc);
 
     try t.title.ensureTotalCapacityPrecise(alloc, 5);
@@ -4110,7 +4245,7 @@ test "Terminal: setTitle preserves a sentinel on allocation failure" {
 }
 
 test "Terminal: setTitle accepts its current value" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 1 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 1 });
     defer t.deinit(testing.allocator);
 
     try t.setTitle("Ghostty");
@@ -4146,6 +4281,7 @@ pub fn switchScreen(self: *Terminal, key: ScreenSet.Key) !?*Screen {
     const new = self.screens.get(key) orelse new: {
         const primary = self.screens.get(.primary).?;
         break :new try self.screens.getInit(
+            old.io,
             old.alloc,
             key,
             .{
@@ -4357,7 +4493,8 @@ fn clearDirty(t: *Terminal) void {
 
 test "Terminal: setCursorPos saturates overflowing origin offsets" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     t.scrolling_region = .{
@@ -4375,7 +4512,8 @@ test "Terminal: setCursorPos saturates overflowing origin offsets" {
 
 test "Terminal: input with no control characters" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 40, .rows = 40 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 40, .rows = 40 });
     defer t.deinit(alloc);
 
     // Basic grid writing
@@ -4395,7 +4533,8 @@ test "Terminal: input with no control characters" {
 
 test "Terminal: input with basic wraparound" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 40 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 40 });
     defer t.deinit(alloc);
 
     // Basic grid writing
@@ -4412,7 +4551,8 @@ test "Terminal: input with basic wraparound" {
 
 test "Terminal: input with basic wraparound dirty" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 40 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 40 });
     defer t.deinit(alloc);
 
     for ("hello") |c| try t.print(c);
@@ -4427,7 +4567,8 @@ test "Terminal: input with basic wraparound dirty" {
 
 test "Terminal: input that forces scroll" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 1, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 1, .rows = 5 });
     defer t.deinit(alloc);
 
     // Basic grid writing
@@ -4443,7 +4584,8 @@ test "Terminal: input that forces scroll" {
 
 test "Terminal: input unique style per cell" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 30, .rows = 30 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 30, .rows = 30 });
     defer t.deinit(alloc);
 
     for (0..t.rows) |y| {
@@ -4462,7 +4604,8 @@ test "Terminal: input unique style per cell" {
 test "Terminal: input glitch text" {
     const glitch = @embedFile("res/glitch.txt");
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 30, .rows = 30 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 30, .rows = 30 });
     defer t.deinit(alloc);
 
     // Get our initial grapheme capacity.
@@ -4484,7 +4627,7 @@ test "Terminal: input glitch text" {
 }
 
 test "Terminal: zero-width character at start" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // This used to crash the terminal. This is not allowed so we should
@@ -4500,7 +4643,7 @@ test "Terminal: zero-width character at start" {
 
 // https://github.com/ghostty-org/ghostty/pull/12581
 test "Terminal: zero-width character attaches to pending wrap cell" {
-    var t = try init(testing.allocator, .{ .cols = 2, .rows = 2 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 2, .rows = 2 });
     defer t.deinit(testing.allocator);
 
     // Disable grapheme clustering to exercise the fallback path.
@@ -4517,7 +4660,7 @@ test "Terminal: zero-width character attaches to pending wrap cell" {
 
 // https://github.com/mitchellh/ghostty/issues/1400
 test "Terminal: print single very long line" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // This would crash for issue 1400. So the assertion here is
@@ -4526,7 +4669,7 @@ test "Terminal: print single very long line" {
 }
 
 test "Terminal: print wide char" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.print(0x1F600); // Smiley face
@@ -4536,7 +4679,7 @@ test "Terminal: print wide char" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F600), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F600), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
     {
@@ -4549,7 +4692,7 @@ test "Terminal: print wide char" {
 }
 
 test "Terminal: print wide char at edge creates spacer head" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     t.setCursorPos(1, 10);
@@ -4565,7 +4708,7 @@ test "Terminal: print wide char at edge creates spacer head" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F600), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F600), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
     {
@@ -4584,7 +4727,8 @@ test "Terminal: print wide char at edge creates spacer head" {
 
 test "Terminal: print wide char with 1-column width" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 1, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 1, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.print('😀'); // 0x1F600
@@ -4594,7 +4738,7 @@ test "Terminal: print wide char with 1-column width" {
 }
 
 test "Terminal: print wide char in single-width terminal" {
-    var t = try init(testing.allocator, .{ .cols = 1, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 1, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.print(0x1F600); // Smiley face
@@ -4605,7 +4749,7 @@ test "Terminal: print wide char in single-width terminal" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 
@@ -4613,7 +4757,7 @@ test "Terminal: print wide char in single-width terminal" {
 }
 
 test "Terminal: print over wide char at 0,0" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.print(0x1F600); // Smiley face
@@ -4626,13 +4770,13 @@ test "Terminal: print over wide char at 0,0" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 
@@ -4648,7 +4792,8 @@ test "Terminal: print over wide char at col 0 corrupts previous row" {
     // when that cell is a .spacer_tail rather than a .spacer_head. This
     // orphans the .wide cell at cols-2.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     // Fill rows 0 and 1 with wide chars (5 per row on a 10-col terminal).
@@ -4679,7 +4824,7 @@ test "Terminal: print over wide char at col 0 corrupts previous row" {
 }
 
 test "Terminal: print over wide spacer tail" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     try t.print('橋');
@@ -4689,13 +4834,13 @@ test "Terminal: print over wide spacer tail" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'X'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'X'), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 
@@ -4709,7 +4854,7 @@ test "Terminal: print over wide spacer tail" {
 }
 
 test "Terminal: print over wide char with bold" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.setAttribute(.{ .bold = {} });
@@ -4735,7 +4880,7 @@ test "Terminal: print over wide char with bold" {
 }
 
 test "Terminal: print over wide char with bg color" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.setAttribute(.{ .direct_color_bg = .{
@@ -4765,7 +4910,7 @@ test "Terminal: print over wide char with bg color" {
 }
 
 test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // https://github.com/mitchellh/ghostty/issues/289
@@ -4785,7 +4930,7 @@ test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F468), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F468), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -4794,7 +4939,7 @@ test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
         try testing.expect(list_cell.node.page().lookupGrapheme(cell) == null);
@@ -4802,7 +4947,7 @@ test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F469), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F469), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -4811,7 +4956,7 @@ test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 3, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
         try testing.expect(list_cell.node.page().lookupGrapheme(cell) == null);
@@ -4819,7 +4964,7 @@ test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 4, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F467), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F467), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         try testing.expect(list_cell.node.page().lookupGrapheme(cell) == null);
@@ -4827,7 +4972,7 @@ test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 5, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
         try testing.expect(list_cell.node.page().lookupGrapheme(cell) == null);
@@ -4837,7 +4982,7 @@ test "Terminal: print multicodepoint grapheme, disabled mode 2027" {
 }
 
 test "Terminal: enabling grapheme mode handles stored breaks" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 1 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 1 });
     defer t.deinit(testing.allocator);
 
     t.modes.set(.grapheme_cluster, false);
@@ -4857,7 +5002,7 @@ test "Terminal: enabling grapheme mode handles stored breaks" {
 // cluster or string end. This keeps the streaming printer's cursor advance
 // in sync with the buffered measurement API for representative clusters.
 fn expectGraphemeWidthParity(cps: []const u21) !void {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     t.modes.set(.grapheme_cluster, true);
@@ -4891,7 +5036,7 @@ test "Terminal: graphemeWidth parity" {
 }
 
 test "Terminal: VS16 doesn't make character with 2027 disabled" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Disable grapheme clustering
@@ -4909,7 +5054,7 @@ test "Terminal: VS16 doesn't make character with 2027 disabled" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -4918,7 +5063,7 @@ test "Terminal: VS16 doesn't make character with 2027 disabled" {
 }
 
 test "Terminal: ignored VS16 doesn't mark dirty" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Disable grapheme clustering
@@ -4933,7 +5078,7 @@ test "Terminal: ignored VS16 doesn't mark dirty" {
 }
 
 test "Terminal: print invalid VS16 non-grapheme" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // https://github.com/mitchellh/ghostty/issues/1482
@@ -4949,19 +5094,19 @@ test "Terminal: print invalid VS16 non-grapheme" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'x'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'x'), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
     }
 }
 
 test "Terminal: invalid VS16 doesn't mark dirty" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Disable grapheme clustering
@@ -4977,7 +5122,7 @@ test "Terminal: invalid VS16 doesn't mark dirty" {
 
 // https://github.com/ghostty-org/ghostty/pull/12596
 test "Terminal: variation selectors apply to preceding codepoint" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -4991,13 +5136,13 @@ test "Terminal: variation selectors apply to preceding codepoint" {
 
     const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
     const cell = list_cell.cell;
-    try testing.expectEqual(@as(u21, 0x1F3F4), cell.content.codepoint);
+    try testing.expectEqual(@as(u21, 0x1F3F4), cell.content.codepoint.data);
     try testing.expect(cell.hasGrapheme());
     try testing.expectEqualSlices(u21, &.{ 0x200D, 0x2620, 0xFE0F }, list_cell.node.page().lookupGrapheme(cell).?);
 }
 
 test "Terminal: print multicodepoint grapheme, mode 2027" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5023,7 +5168,7 @@ test "Terminal: print multicodepoint grapheme, mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F468), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F468), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -5032,14 +5177,14 @@ test "Terminal: print multicodepoint grapheme, mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
     }
 }
 
 test "Terminal: keypad sequence VS15" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5061,14 +5206,14 @@ test "Terminal: keypad sequence VS15" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x23), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x23), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: keypad sequence VS16" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5090,14 +5235,14 @@ test "Terminal: keypad sequence VS16" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x23), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x23), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
 }
 
 test "Terminal: Fitzpatrick skin tone next valid base" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5119,14 +5264,14 @@ test "Terminal: Fitzpatrick skin tone next valid base" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F44B), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F44B), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
 }
 
 test "Terminal: Fitzpatrick skin tone next to non-base" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5150,28 +5295,28 @@ test "Terminal: Fitzpatrick skin tone next to non-base" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x22), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x22), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F3FF), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F3FF), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 3, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x22), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x22), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: multicodepoint grapheme marks dirty on every codepoint" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5200,7 +5345,7 @@ test "Terminal: multicodepoint grapheme marks dirty on every codepoint" {
 }
 
 test "Terminal: VS15 to make narrow character" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5231,7 +5376,7 @@ test "Terminal: VS15 to make narrow character" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x2614), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x2614), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -5240,7 +5385,7 @@ test "Terminal: VS15 to make narrow character" {
 }
 
 test "Terminal: VS15 on already narrow emoji" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5266,7 +5411,7 @@ test "Terminal: VS15 on already narrow emoji" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x26C8), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x26C8), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -5275,7 +5420,7 @@ test "Terminal: VS15 on already narrow emoji" {
 }
 
 test "Terminal: print invalid VS15 following emoji is wide" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5293,20 +5438,20 @@ test "Terminal: print invalid VS15 following emoji is wide" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '\u{1F9E0}'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '\u{1F9E0}'), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
     }
 }
 
 test "Terminal: print invalid VS15 in emoji ZWJ sequence" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5326,7 +5471,7 @@ test "Terminal: print invalid VS15 in emoji ZWJ sequence" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '\u{1F469}'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '\u{1F469}'), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{ '\u{200D}', '\u{1F466}' }, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
@@ -5334,13 +5479,13 @@ test "Terminal: print invalid VS15 in emoji ZWJ sequence" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
     }
 }
 
 test "Terminal: VS15 to make narrow character with pending wrap" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 4 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 4 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5377,7 +5522,7 @@ test "Terminal: VS15 to make narrow character with pending wrap" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x2614), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x2614), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -5387,16 +5532,16 @@ test "Terminal: VS15 to make narrow character with pending wrap" {
     // VS15 should not affect the previous grapheme
     {
         const lemon_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?.cell;
-        try testing.expectEqual(@as(u21, 0x1F34B), lemon_cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F34B), lemon_cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.wide, lemon_cell.wide);
         const spacer_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?.cell;
-        try testing.expectEqual(@as(u21, 0), spacer_cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), spacer_cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.spacer_tail, spacer_cell.wide);
     }
 }
 
 test "Terminal: VS16 to make wide character on next line" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 3 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 3 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5421,7 +5566,7 @@ test "Terminal: VS16 to make wide character on next line" {
         // Previous cell turns into spacer_head
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_head, cell.wide);
     }
@@ -5429,7 +5574,7 @@ test "Terminal: VS16 to make wide character on next line" {
         // '#' cell is wide
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '#'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '#'), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{0xFE0F}, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
@@ -5438,7 +5583,7 @@ test "Terminal: VS16 to make wide character on next line" {
         // spacer_tail
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
     }
@@ -5447,7 +5592,7 @@ test "Terminal: VS16 to make wide character on next line" {
 test "Terminal: VS16 to make wide character on next line with hyperlink" {
     // Regression test for the crash fixed in print's grapheme `.wide` path:
     // writing a spacer_head at the screen edge before row.wrap was set.
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 3 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 3 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering and activate a hyperlink so printCell
@@ -5471,7 +5616,7 @@ test "Terminal: VS16 to make wide character on next line with hyperlink" {
         // Previous cell turns into spacer_head and remains hyperlinked.
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.spacer_head, cell.wide);
         try testing.expect(cell.hyperlink);
         try testing.expect(list_cell.row.wrap);
@@ -5480,7 +5625,7 @@ test "Terminal: VS16 to make wide character on next line with hyperlink" {
         // '#' cell is now wide and still hyperlinked.
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '#'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '#'), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{0xFE0F}, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
@@ -5490,14 +5635,14 @@ test "Terminal: VS16 to make wide character on next line with hyperlink" {
         // spacer_tail inherits hyperlink as part of the same grapheme cell.
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
         try testing.expect(cell.hyperlink);
     }
 }
 
 test "Terminal: VS16 to make wide character with pending wrap" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 3 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 3 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5518,7 +5663,7 @@ test "Terminal: VS16 to make wide character with pending wrap" {
         // '#' cell is wide
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '#'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '#'), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{0xFE0F}, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
@@ -5527,14 +5672,14 @@ test "Terminal: VS16 to make wide character with pending wrap" {
         // spacer_tail
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
     }
 }
 
 test "Terminal: VS16 to make wide character with mode 2027" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5556,7 +5701,7 @@ test "Terminal: VS16 to make wide character with mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -5565,7 +5710,7 @@ test "Terminal: VS16 to make wide character with mode 2027" {
 }
 
 test "Terminal: VS16 repeated with mode 2027" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5587,7 +5732,7 @@ test "Terminal: VS16 repeated with mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -5596,7 +5741,7 @@ test "Terminal: VS16 repeated with mode 2027" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x2764), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
         const cps = list_cell.node.page().lookupGrapheme(cell).?;
@@ -5605,7 +5750,7 @@ test "Terminal: VS16 repeated with mode 2027" {
 }
 
 test "Terminal: print invalid VS16 grapheme" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5624,20 +5769,20 @@ test "Terminal: print invalid VS16 grapheme" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'x'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'x'), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: print invalid VS16 with second char" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5657,7 +5802,7 @@ test "Terminal: print invalid VS16 with second char" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'x'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'x'), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
@@ -5665,14 +5810,14 @@ test "Terminal: print invalid VS16 with second char" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'y'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'y'), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: print grapheme ò (o with nonspacing mark) should be narrow" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5690,7 +5835,7 @@ test "Terminal: print grapheme ò (o with nonspacing mark) should be narrow" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'o'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'o'), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{0x0300}, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
@@ -5698,7 +5843,7 @@ test "Terminal: print grapheme ò (o with nonspacing mark) should be narrow" {
 }
 
 test "Terminal: print Devanagari grapheme should be wide" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5719,7 +5864,7 @@ test "Terminal: print Devanagari grapheme should be wide" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x0915), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x0915), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{ 0x094D, 0x200D, 0x0937 }, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
@@ -5732,7 +5877,7 @@ test "Terminal: print Devanagari grapheme should be wide" {
 }
 
 test "Terminal: print Devanagari grapheme should be wide on next line" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 3 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 3 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5759,7 +5904,7 @@ test "Terminal: print Devanagari grapheme should be wide on next line" {
         // Previous cell turns into spacer_head
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_head, cell.wide);
     }
@@ -5767,7 +5912,7 @@ test "Terminal: print Devanagari grapheme should be wide on next line" {
         // Devanagari grapheme is wide
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x0915), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x0915), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{ 0x094D, 0x200D, 0x0937 }, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
@@ -5782,7 +5927,7 @@ test "Terminal: print Devanagari grapheme should be wide on next line" {
 test "Terminal: print Devanagari grapheme should be wide on next page" {
     const rows = pagepkg.std_capacity.rows;
     const cols = pagepkg.std_capacity.cols;
-    var t = try init(testing.allocator, .{ .rows = rows, .cols = cols });
+    var t = try init(testing.io, testing.allocator, .{ .rows = rows, .cols = cols });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5818,7 +5963,7 @@ test "Terminal: print Devanagari grapheme should be wide on next page" {
         // Previous cell turns into spacer_head
         const list_cell = t.screens.active.pages.getCell(.{ .active = .{ .x = cols - 1, .y = rows - 2 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.spacer_head, cell.wide);
     }
@@ -5826,7 +5971,7 @@ test "Terminal: print Devanagari grapheme should be wide on next page" {
         // Devanagari grapheme is wide
         const list_cell = t.screens.active.pages.getCell(.{ .active = .{ .x = 0, .y = rows - 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x0915), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x0915), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{ 0x094D, 0x200D, 0x0937 }, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
@@ -5839,7 +5984,7 @@ test "Terminal: print Devanagari grapheme should be wide on next page" {
 }
 
 test "Terminal: print invalid VS16 with second char (combining)" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5859,7 +6004,7 @@ test "Terminal: print invalid VS16 with second char (combining)" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'n'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'n'), cell.content.codepoint.data);
         try testing.expect(cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{'\u{0303}'}, list_cell.node.page().lookupGrapheme(cell).?);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
@@ -5867,13 +6012,13 @@ test "Terminal: print invalid VS16 with second char (combining)" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: overwrite grapheme should clear grapheme data" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5897,14 +6042,14 @@ test "Terminal: overwrite grapheme should clear grapheme data" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: overwrite multicodepoint grapheme clears grapheme data" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5944,7 +6089,7 @@ test "Terminal: overwrite multicodepoint grapheme clears grapheme data" {
 }
 
 test "Terminal: overwrite multicodepoint grapheme tail clears grapheme data" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     // Enable grapheme clustering
@@ -5983,7 +6128,8 @@ test "Terminal: overwrite multicodepoint grapheme tail clears grapheme data" {
 
 test "Terminal: print breaks valid grapheme cluster with Prepend + ASCII for speed" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -6010,7 +6156,7 @@ test "Terminal: print breaks valid grapheme cluster with Prepend + ASCII for spe
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x0600), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x0600), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         // This is what we'd expect if we did break correctly:
         //try testing.expect(cell.hasGrapheme());
@@ -6020,16 +6166,16 @@ test "Terminal: print breaks valid grapheme cluster with Prepend + ASCII for spe
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '1'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '1'), cell.content.codepoint.data);
         // This is what we'd expect if we did break correctly:
-        //try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        //try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expect(!cell.hasGrapheme());
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: print writes to bottom if scrolled" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 2 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 2 });
     defer t.deinit(testing.allocator);
 
     // Basic grid writing
@@ -6071,7 +6217,7 @@ test "Terminal: print writes to bottom if scrolled" {
 }
 
 test "Terminal: print charset" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // G1 should have no effect
@@ -6100,7 +6246,7 @@ test "Terminal: print charset" {
 }
 
 test "Terminal: print charset outside of ASCII" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // G1 should have no effect
@@ -6125,7 +6271,7 @@ test "Terminal: print charset outside of ASCII" {
 }
 
 test "Terminal: print invoke charset" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     t.configureCharset(.G1, .dec_special);
@@ -6149,7 +6295,7 @@ test "Terminal: print invoke charset" {
 }
 
 test "Terminal: print invoke charset single" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     t.configureCharset(.G1, .dec_special);
@@ -6169,7 +6315,7 @@ test "Terminal: print invoke charset single" {
 test "Terminal: print kitty unicode placeholder" {
     if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
 
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     try t.print(kitty.graphics.unicode.placeholder);
@@ -6179,7 +6325,7 @@ test "Terminal: print kitty unicode placeholder" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, kitty.graphics.unicode.placeholder), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, kitty.graphics.unicode.placeholder), cell.content.codepoint.data);
         try testing.expect(list_cell.row.kitty_virtual_placeholder);
     }
 
@@ -6187,7 +6333,7 @@ test "Terminal: print kitty unicode placeholder" {
 }
 
 test "Terminal: soft wrap" {
-    var t = try init(testing.allocator, .{ .cols = 3, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 3, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Basic grid writing
@@ -6202,7 +6348,7 @@ test "Terminal: soft wrap" {
 }
 
 test "Terminal: soft wrap with semantic prompt" {
-    var t = try init(testing.allocator, .{ .cols = 3, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 3, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Mark our prompt.
@@ -6223,7 +6369,7 @@ test "Terminal: soft wrap with semantic prompt" {
 }
 
 test "Terminal: disabled wraparound with wide char and one space" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     t.modes.set(.wraparound, false);
@@ -6246,7 +6392,7 @@ test "Terminal: disabled wraparound with wide char and one space" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 4, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 
@@ -6255,7 +6401,7 @@ test "Terminal: disabled wraparound with wide char and one space" {
 }
 
 test "Terminal: disabled wraparound with wide char and no space" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     t.modes.set(.wraparound, false);
@@ -6277,7 +6423,7 @@ test "Terminal: disabled wraparound with wide char and no space" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 4, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 
@@ -6286,7 +6432,7 @@ test "Terminal: disabled wraparound with wide char and no space" {
 }
 
 test "Terminal: disabled wraparound with wide grapheme and half space" {
-    var t = try init(testing.allocator, .{ .rows = 5, .cols = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .rows = 5, .cols = 5 });
     defer t.deinit(testing.allocator);
 
     t.modes.set(.grapheme_cluster, true);
@@ -6310,7 +6456,7 @@ test "Terminal: disabled wraparound with wide grapheme and half space" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 4, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '❤'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '❤'), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 
@@ -6319,7 +6465,7 @@ test "Terminal: disabled wraparound with wide grapheme and half space" {
 }
 
 test "Terminal: print right margin wrap" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     try t.printString("123456789");
@@ -6342,7 +6488,7 @@ test "Terminal: print right margin wrap" {
 }
 
 test "Terminal: print right margin wrap dirty tracking" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     try t.printString("123456789");
@@ -6371,7 +6517,7 @@ test "Terminal: print right margin wrap dirty tracking" {
 }
 
 test "Terminal: print right margin outside" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     try t.printString("123456789");
@@ -6391,7 +6537,7 @@ test "Terminal: print right margin outside" {
 }
 
 test "Terminal: print right margin outside wrap" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     try t.printString("123456789");
@@ -6408,7 +6554,7 @@ test "Terminal: print right margin outside wrap" {
 }
 
 test "Terminal: print wide char at right margin does not create spacer head" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     t.modes.set(.enable_left_and_right_margin, true);
@@ -6425,7 +6571,7 @@ test "Terminal: print wide char at right margin does not create spacer head" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 4, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
 
         const row = list_cell.row;
@@ -6434,7 +6580,7 @@ test "Terminal: print wide char at right margin does not create spacer head" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 2, .y = 1 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x1F600), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x1F600), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
     {
@@ -6445,7 +6591,7 @@ test "Terminal: print wide char at right margin does not create spacer head" {
 }
 
 test "Terminal: print with hyperlink" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Setup our hyperlink and print
@@ -6470,7 +6616,7 @@ test "Terminal: print with hyperlink" {
 }
 
 test "Terminal: print over cell with same hyperlink" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Setup our hyperlink and print
@@ -6497,7 +6643,7 @@ test "Terminal: print over cell with same hyperlink" {
 }
 
 test "Terminal: print and end hyperlink" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Setup our hyperlink and print
@@ -6534,7 +6680,7 @@ test "Terminal: print and end hyperlink" {
 }
 
 test "Terminal: print and change hyperlink" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Setup our hyperlink and print
@@ -6569,7 +6715,7 @@ test "Terminal: print and change hyperlink" {
 }
 
 test "Terminal: overwrite hyperlink" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Setup our hyperlink and print
@@ -6602,7 +6748,7 @@ test "Terminal: overwrite hyperlink" {
 // flag. The integrity check inside setHyperlink (or increaseCapacity)
 // sees the unwrapped spacer head and panics. Found via fuzzing.
 test "Terminal: print wide char at right edge with hyperlink" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 5 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -6629,7 +6775,7 @@ test "Terminal: print wide char at right edge with hyperlink" {
     // Row 1, col 0: the wide char with hyperlink
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 1 } }).?;
-        try testing.expectEqual(@as(u21, 0x4E2D), list_cell.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x4E2D), list_cell.cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.wide, list_cell.cell.wide);
         try testing.expect(list_cell.cell.hyperlink);
     }
@@ -6642,7 +6788,7 @@ test "Terminal: print wide char at right edge with hyperlink" {
 }
 
 test "Terminal: linefeed and carriage return" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Print and CR.
@@ -6670,7 +6816,7 @@ test "Terminal: linefeed and carriage return" {
 }
 
 test "Terminal: linefeed unsets pending wrap" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Basic grid writing
@@ -6684,7 +6830,7 @@ test "Terminal: linefeed unsets pending wrap" {
 }
 
 test "Terminal: linefeed mode automatic carriage return" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     // Basic grid writing
@@ -6700,7 +6846,7 @@ test "Terminal: linefeed mode automatic carriage return" {
 }
 
 test "Terminal: carriage return unsets pending wrap" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Basic grid writing
@@ -6711,7 +6857,7 @@ test "Terminal: carriage return unsets pending wrap" {
 }
 
 test "Terminal: carriage return origin mode moves to left margin" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     t.modes.set(.origin, true);
@@ -6722,7 +6868,7 @@ test "Terminal: carriage return origin mode moves to left margin" {
 }
 
 test "Terminal: carriage return left of left margin moves to zero" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     t.screens.active.cursor.x = 1;
@@ -6732,7 +6878,7 @@ test "Terminal: carriage return left of left margin moves to zero" {
 }
 
 test "Terminal: carriage return right of left margin moves to left margin" {
-    var t = try init(testing.allocator, .{ .cols = 5, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 5, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     t.screens.active.cursor.x = 3;
@@ -6742,7 +6888,7 @@ test "Terminal: carriage return right of left margin moves to left margin" {
 }
 
 test "Terminal: backspace" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // BS
@@ -6760,7 +6906,8 @@ test "Terminal: backspace" {
 
 test "Terminal: horizontal tabs" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 20, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 20, .rows = 5 });
     defer t.deinit(alloc);
 
     // HT
@@ -6781,7 +6928,8 @@ test "Terminal: horizontal tabs" {
 
 test "Terminal: horizontal tabs starting on tabstop" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 20, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 20, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(t.screens.active.cursor.y, 9);
@@ -6799,7 +6947,8 @@ test "Terminal: horizontal tabs starting on tabstop" {
 
 test "Terminal: horizontal tabs with right margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 20, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 20, .rows = 5 });
     defer t.deinit(alloc);
 
     t.scrolling_region.left = 2;
@@ -6818,7 +6967,8 @@ test "Terminal: horizontal tabs with right margin" {
 
 test "Terminal: horizontal tabs back" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 20, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 20, .rows = 5 });
     defer t.deinit(alloc);
 
     // Edge of screen
@@ -6841,7 +6991,8 @@ test "Terminal: horizontal tabs back" {
 
 test "Terminal: horizontal tabs back starting on tabstop" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 20, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 20, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(t.screens.active.cursor.y, 9);
@@ -6859,7 +7010,8 @@ test "Terminal: horizontal tabs back starting on tabstop" {
 
 test "Terminal: horizontal tabs with left margin in origin mode" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 20, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 20, .rows = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.origin, true);
@@ -6879,7 +7031,8 @@ test "Terminal: horizontal tabs with left margin in origin mode" {
 
 test "Terminal: horizontal tab back with cursor before left margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 20, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 20, .rows = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.origin, true);
@@ -6899,7 +7052,8 @@ test "Terminal: horizontal tab back with cursor before left margin" {
 
 test "Terminal: cursorPos resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -6917,7 +7071,8 @@ test "Terminal: cursorPos resets wrap" {
 
 test "Terminal: cursorPos off the screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(500, 500);
@@ -6932,7 +7087,8 @@ test "Terminal: cursorPos off the screen" {
 
 test "Terminal: cursorPos relative to origin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.scrolling_region.top = 2;
@@ -6950,7 +7106,8 @@ test "Terminal: cursorPos relative to origin" {
 
 test "Terminal: cursorPos relative to origin with left/right" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.scrolling_region.top = 2;
@@ -6970,7 +7127,8 @@ test "Terminal: cursorPos relative to origin with left/right" {
 
 test "Terminal: cursorPos limits with full scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.scrolling_region.top = 2;
@@ -6990,7 +7148,7 @@ test "Terminal: cursorPos limits with full scroll region" {
 
 // Probably outdated, but dates back to the original terminal implementation.
 test "Terminal: setCursorPos (original test)" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try testing.expectEqual(@as(usize, 0), t.screens.active.cursor.x);
@@ -7043,7 +7201,8 @@ test "Terminal: setCursorPos (original test)" {
 
 test "Terminal: setTopAndBottomMargin simple" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7073,7 +7232,8 @@ test "Terminal: setTopAndBottomMargin simple" {
 
 test "Terminal: setTopAndBottomMargin top only" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7103,7 +7263,8 @@ test "Terminal: setTopAndBottomMargin top only" {
 
 test "Terminal: setTopAndBottomMargin top and bottom" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7131,7 +7292,8 @@ test "Terminal: setTopAndBottomMargin top and bottom" {
 
 test "Terminal: setTopAndBottomMargin top equal to bottom" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7160,7 +7322,8 @@ test "Terminal: setTopAndBottomMargin top equal to bottom" {
 
 test "Terminal: setLeftAndRightMargin simple" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7188,7 +7351,8 @@ test "Terminal: setLeftAndRightMargin simple" {
 
 test "Terminal: setLeftAndRightMargin left only" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7221,7 +7385,8 @@ test "Terminal: setLeftAndRightMargin left only" {
 
 test "Terminal: setLeftAndRightMargin left and right" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7252,7 +7417,8 @@ test "Terminal: setLeftAndRightMargin left and right" {
 
 test "Terminal: setLeftAndRightMargin left equal right" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7283,7 +7449,8 @@ test "Terminal: setLeftAndRightMargin left equal right" {
 
 test "Terminal: setLeftAndRightMargin mode 69 unset" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7314,7 +7481,8 @@ test "Terminal: setLeftAndRightMargin mode 69 unset" {
 
 test "Terminal: insertLines simple" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7346,7 +7514,8 @@ test "Terminal: insertLines simple" {
 
 test "Terminal: insertLines colors with bg color" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7387,7 +7556,8 @@ test "Terminal: insertLines colors with bg color" {
 
 test "Terminal: insertLines handles style refs" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7421,7 +7591,8 @@ test "Terminal: insertLines handles style refs" {
 
 test "Terminal: insertLines outside of scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7450,7 +7621,8 @@ test "Terminal: insertLines outside of scroll region" {
 
 test "Terminal: insertLines top/bottom scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7483,7 +7655,8 @@ test "Terminal: insertLines top/bottom scroll region" {
 
 test "Terminal: insertLines across page boundary marks all shifted rows dirty" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
     defer t.deinit(alloc);
 
     const first_page = t.screens.active.pages.pages.first.?;
@@ -7537,7 +7710,8 @@ test "Terminal: insertLines hyperlink-dense row crosses page boundary" {
     // page's hyperlink capacity, the copy must increase the destination
     // page's capacity and retry rather than corrupting the page list.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
     defer t.deinit(alloc);
 
     const pages = &t.screens.active.pages;
@@ -7618,7 +7792,8 @@ test "Terminal: insertLines hyperlink-dense row crosses page boundary" {
 
 test "Terminal: insertLines (legacy test)" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -7651,7 +7826,8 @@ test "Terminal: insertLines (legacy test)" {
 
 test "Terminal: insertLines zero" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     // This should do nothing
@@ -7661,7 +7837,8 @@ test "Terminal: insertLines zero" {
 
 test "Terminal: insertLines with scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 6 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 6 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -7700,7 +7877,8 @@ test "Terminal: insertLines with scroll region" {
 
 test "Terminal: insertLines more than remaining" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -7738,7 +7916,8 @@ test "Terminal: insertLines more than remaining" {
 
 test "Terminal: insertLines resets pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -7756,7 +7935,8 @@ test "Terminal: insertLines resets pending wrap" {
 
 test "Terminal: insertLines resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 3, .cols = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     try t.print('1');
@@ -7782,7 +7962,8 @@ test "Terminal: insertLines resets wrap" {
 
 test "Terminal: insertLines multi-codepoint graphemes" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Disable grapheme clustering
@@ -7814,7 +7995,8 @@ test "Terminal: insertLines multi-codepoint graphemes" {
 
 test "Terminal: insertLines left/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -7845,7 +8027,8 @@ test "Terminal: insertLines left/right scroll region" {
 
 test "Terminal: scrollUp simple" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7878,7 +8061,8 @@ test "Terminal: scrollUp simple" {
 
 test "Terminal: scrollUp moves hyperlink" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7929,7 +8113,8 @@ test "Terminal: scrollUp moves hyperlink" {
 
 test "Terminal: scrollUp clears hyperlink" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -7966,7 +8151,8 @@ test "Terminal: scrollUp clears hyperlink" {
 
 test "Terminal: scrollUp top/bottom scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -7996,7 +8182,8 @@ test "Terminal: scrollUp top/bottom scroll region" {
 
 test "Terminal: scrollUp left/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -8029,7 +8216,8 @@ test "Terminal: scrollUp left/right scroll region" {
 
 test "Terminal: scrollUp left/right scroll region hyperlink" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -8135,7 +8323,8 @@ test "Terminal: scrollUp left/right scroll region hyperlink" {
 
 test "Terminal: scrollUp preserves pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(1, 5);
@@ -8156,7 +8345,8 @@ test "Terminal: scrollUp preserves pending wrap" {
 
 test "Terminal: scrollUp full top/bottom region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("top");
@@ -8180,7 +8370,8 @@ test "Terminal: scrollUp full top/bottom region" {
 
 test "Terminal: scrollUp full top/bottomleft/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("top");
@@ -8211,7 +8402,8 @@ test "Terminal: scrollUp creates scrollback in primary screen" {
     // When in primary screen with full-width scroll region at top,
     // scrollUp (CSI S) should push lines into scrollback like xterm.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 10 });
     defer t.deinit(alloc);
 
     // Fill the screen with content
@@ -8257,7 +8449,8 @@ test "Terminal: scrollUp creates scrollback in primary screen" {
 test "Terminal: scrollUp with max_scrollback zero" {
     // When max_scrollback is 0, scrollUp should still work but not retain history
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
     defer t.deinit(alloc);
 
     try t.printString("AAAAA");
@@ -8289,7 +8482,8 @@ test "Terminal: scrollUp with max_scrollback zero" {
 test "Terminal: scrollUp with max_scrollback zero and top margin" {
     // When max_scrollback is 0 and top margin is set, should use deleteLines path
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
     defer t.deinit(alloc);
 
     try t.printString("AAAAA");
@@ -8319,7 +8513,8 @@ test "Terminal: scrollUp with max_scrollback zero and top margin" {
 test "Terminal: scrollUp with max_scrollback zero and left/right margin" {
     // When max_scrollback is 0 with left/right margins, uses deleteLines path
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 0 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 0 });
     defer t.deinit(alloc);
 
     try t.printString("AAAAABBBBB");
@@ -8346,7 +8541,8 @@ test "Terminal: scrollUp with max_scrollback zero and left/right margin" {
 
 test "Terminal: scrollDown simple" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -8378,7 +8574,8 @@ test "Terminal: scrollDown simple" {
 
 test "Terminal: scrollDown hyperlink moves" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -8429,7 +8626,8 @@ test "Terminal: scrollDown hyperlink moves" {
 
 test "Terminal: scrollDown outside of scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -8464,7 +8662,8 @@ test "Terminal: scrollDown outside of scroll region" {
 
 test "Terminal: scrollDown left/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -8498,7 +8697,8 @@ test "Terminal: scrollDown left/right scroll region" {
 
 test "Terminal: scrollDown left/right scroll region hyperlink" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -8604,7 +8804,8 @@ test "Terminal: scrollDown left/right scroll region hyperlink" {
 
 test "Terminal: scrollDown outside of left/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -8638,7 +8839,8 @@ test "Terminal: scrollDown outside of left/right scroll region" {
 
 test "Terminal: scrollDown preserves pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 10 });
     defer t.deinit(alloc);
 
     t.setCursorPos(1, 5);
@@ -8659,7 +8861,8 @@ test "Terminal: scrollDown preserves pending wrap" {
 
 test "Terminal: eraseChars simple operation" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -8680,7 +8883,8 @@ test "Terminal: eraseChars simple operation" {
 
 test "Terminal: eraseChars minimum one" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -8699,7 +8903,8 @@ test "Terminal: eraseChars minimum one" {
 
 test "Terminal: eraseChars beyond screen edge" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("  ABC") |c| try t.print(c);
@@ -8715,7 +8920,8 @@ test "Terminal: eraseChars beyond screen edge" {
 
 test "Terminal: eraseChars wide character" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('橋');
@@ -8733,7 +8939,8 @@ test "Terminal: eraseChars wide character" {
 
 test "Terminal: eraseChars resets pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -8751,7 +8958,8 @@ test "Terminal: eraseChars resets pending wrap" {
 
 test "Terminal: eraseChars resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE123") |c| try t.print(c);
@@ -8781,7 +8989,8 @@ test "Terminal: eraseChars resets wrap" {
 
 test "Terminal: eraseChars preserves background sgr" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -8820,7 +9029,8 @@ test "Terminal: eraseChars preserves background sgr" {
 
 test "Terminal: eraseChars handles refcounted styles" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.setAttribute(.{ .bold = {} });
@@ -8842,7 +9052,8 @@ test "Terminal: eraseChars handles refcounted styles" {
 
 test "Terminal: eraseChars protected attributes respected with iso" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -8859,7 +9070,8 @@ test "Terminal: eraseChars protected attributes respected with iso" {
 
 test "Terminal: eraseChars protected attributes ignored with dec most recent" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -8878,7 +9090,8 @@ test "Terminal: eraseChars protected attributes ignored with dec most recent" {
 
 test "Terminal: eraseChars protected attributes ignored with dec set" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -8895,7 +9108,8 @@ test "Terminal: eraseChars protected attributes ignored with dec set" {
 
 test "Terminal: eraseChars wide char boundary conditions" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 1, .cols = 8 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 1, .cols = 8 });
     defer t.deinit(alloc);
 
     try t.printString("😀a😀b😀");
@@ -8918,7 +9132,8 @@ test "Terminal: eraseChars wide char boundary conditions" {
 
 test "Terminal: eraseChars wide char splits proper cell boundaries" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 1, .cols = 30 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 1, .cols = 30 });
     defer t.deinit(alloc);
 
     // This is a test for a bug: https://github.com/ghostty-org/ghostty/issues/2817
@@ -8948,7 +9163,8 @@ test "Terminal: eraseChars wide char splits proper cell boundaries" {
 
 test "Terminal: eraseChars wide char wrap boundary conditions" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 3, .cols = 8 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 3, .cols = 8 });
     defer t.deinit(alloc);
 
     try t.printString(".......😀abcde😀......");
@@ -8979,7 +9195,8 @@ test "Terminal: eraseChars wide char wrap boundary conditions" {
 
 test "Terminal: reverseIndex" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -9006,7 +9223,8 @@ test "Terminal: reverseIndex" {
 
 test "Terminal: reverseIndex from the top" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -9039,7 +9257,8 @@ test "Terminal: reverseIndex from the top" {
 
 test "Terminal: reverseIndex top of scrolling region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 10 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -9072,7 +9291,8 @@ test "Terminal: reverseIndex top of scrolling region" {
 
 test "Terminal: reverseIndex top of screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -9093,7 +9313,8 @@ test "Terminal: reverseIndex top of screen" {
 
 test "Terminal: reverseIndex not top of screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -9114,7 +9335,8 @@ test "Terminal: reverseIndex not top of screen" {
 
 test "Terminal: reverseIndex top/bottom margins" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -9135,7 +9357,8 @@ test "Terminal: reverseIndex top/bottom margins" {
 
 test "Terminal: reverseIndex outside top/bottom margins" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -9156,7 +9379,8 @@ test "Terminal: reverseIndex outside top/bottom margins" {
 
 test "Terminal: reverseIndex left/right margins" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -9178,7 +9402,8 @@ test "Terminal: reverseIndex left/right margins" {
 
 test "Terminal: reverseIndex outside left/right margins" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -9200,7 +9425,8 @@ test "Terminal: reverseIndex outside left/right margins" {
 
 test "Terminal: index" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.index();
@@ -9218,7 +9444,8 @@ test "Terminal: index" {
 
 test "Terminal: index from the bottom" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(5, 1);
@@ -9241,7 +9468,8 @@ test "Terminal: index from the bottom" {
 
 test "Terminal: index scrolling with hyperlink" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(5, 1);
@@ -9286,7 +9514,8 @@ test "Terminal: index scrolling with hyperlink" {
 
 test "Terminal: index outside of scrolling region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     try testing.expectEqual(@as(usize, 0), t.screens.active.cursor.y);
@@ -9297,7 +9526,8 @@ test "Terminal: index outside of scrolling region" {
 
 test "Terminal: index from the bottom outside of scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 2);
@@ -9317,7 +9547,8 @@ test "Terminal: index from the bottom outside of scroll region" {
 
 test "Terminal: index no scroll region, top of screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -9337,7 +9568,8 @@ test "Terminal: index no scroll region, top of screen" {
 
 test "Terminal: index bottom of primary screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(5, 1);
@@ -9358,7 +9590,8 @@ test "Terminal: index bottom of primary screen" {
 
 test "Terminal: index bottom of primary screen background sgr" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(5, 1);
@@ -9391,7 +9624,8 @@ test "Terminal: index bottom of primary screen background sgr" {
 
 test "Terminal: index inside scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -9412,7 +9646,8 @@ test "Terminal: index inside scroll region" {
 
 test "Terminal: index bottom of scroll region with hyperlinks" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 2);
@@ -9460,7 +9695,8 @@ test "Terminal: index bottom of scroll region with hyperlinks" {
 
 test "Terminal: index bottom of scroll region clear hyperlinks" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(2, 3);
@@ -9499,7 +9735,8 @@ test "Terminal: index bottom of scroll region clear hyperlinks" {
 
 test "Terminal: index bottom of scroll region with background SGR" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -9536,7 +9773,8 @@ test "Terminal: index bottom of scroll region with background SGR" {
 
 test "Terminal: index bottom of primary screen with scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -9564,7 +9802,8 @@ test "Terminal: index bottom of primary screen with scroll region" {
 
 test "Terminal: index outside left/right margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -9588,7 +9827,8 @@ test "Terminal: index outside left/right margin" {
 
 test "Terminal: index inside left/right margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.printString("AAAAAA");
@@ -9622,7 +9862,8 @@ test "Terminal: index inside left/right margin" {
 
 test "Terminal: index bottom of scroll region creates scrollback" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -9647,7 +9888,8 @@ test "Terminal: index bottom of scroll region creates scrollback" {
 
 test "Terminal: index bottom of scroll region no scrollback" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -9668,7 +9910,8 @@ test "Terminal: index bottom of scroll region no scrollback" {
 
 test "Terminal: index bottom of scroll region blank line preserves SGR" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -9709,7 +9952,8 @@ test "Terminal: index bottom of scroll region blank line preserves SGR" {
 
 test "Terminal: index bottom of scroll region with top margin and background SGR" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("1\n2\n3\n4\n5");
@@ -9749,7 +9993,8 @@ test "Terminal: index bottom of scroll region with top margin and background SGR
 
 test "Terminal: index bottom of alt screen full region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 3, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 3, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.switchScreenMode(.@"1049", true);
@@ -9782,7 +10027,8 @@ test "Terminal: index bottom of alt screen full region" {
 
 test "Terminal: index bottom of alt screen top region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.switchScreenMode(.@"1049", true);
@@ -9809,7 +10055,8 @@ test "Terminal: index bottom of alt screen top region" {
 
 test "Terminal: scrollUp top region no scrollback" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5, .max_scrollback = 0 });
     defer t.deinit(alloc);
 
     try t.printString("A\nB\nC\nD\nE");
@@ -9831,7 +10078,8 @@ test "Terminal: scrollUp top region no scrollback" {
 
 test "Terminal: cursorUp basic" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(3, 1);
@@ -9848,7 +10096,8 @@ test "Terminal: cursorUp basic" {
 
 test "Terminal: cursorUp below top scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(2, 4);
@@ -9866,7 +10115,8 @@ test "Terminal: cursorUp below top scroll margin" {
 
 test "Terminal: cursorUp above top scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(3, 5);
@@ -9885,7 +10135,8 @@ test "Terminal: cursorUp above top scroll margin" {
 
 test "Terminal: cursorUp resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -9903,7 +10154,8 @@ test "Terminal: cursorUp resets wrap" {
 
 test "Terminal: cursorLeft no wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -9921,7 +10173,8 @@ test "Terminal: cursorLeft no wrap" {
 
 test "Terminal: cursorLeft unsets pending wrap state" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -9939,7 +10192,8 @@ test "Terminal: cursorLeft unsets pending wrap state" {
 
 test "Terminal: cursorLeft unsets pending wrap state with longer jump" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -9957,7 +10211,8 @@ test "Terminal: cursorLeft unsets pending wrap state with longer jump" {
 
 test "Terminal: cursorLeft reverse wrap with pending wrap state" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -9978,7 +10233,8 @@ test "Terminal: cursorLeft reverse wrap with pending wrap state" {
 
 test "Terminal: cursorLeft reverse wrap extended with pending wrap state" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -9999,7 +10255,8 @@ test "Terminal: cursorLeft reverse wrap extended with pending wrap state" {
 
 test "Terminal: cursorLeft reverse wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10019,7 +10276,8 @@ test "Terminal: cursorLeft reverse wrap" {
 
 test "Terminal: cursorLeft reverse wrap with no soft wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10041,7 +10299,8 @@ test "Terminal: cursorLeft reverse wrap with no soft wrap" {
 
 test "Terminal: cursorLeft reverse wrap before left margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10059,7 +10318,8 @@ test "Terminal: cursorLeft reverse wrap before left margin" {
 
 test "Terminal: cursorLeft extended reverse wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10081,7 +10341,8 @@ test "Terminal: cursorLeft extended reverse wrap" {
 
 test "Terminal: cursorLeft extended reverse wrap bottom wraparound" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10103,7 +10364,8 @@ test "Terminal: cursorLeft extended reverse wrap bottom wraparound" {
 
 test "Terminal: cursorLeft extended reverse wrap is priority if both set" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10126,7 +10388,8 @@ test "Terminal: cursorLeft extended reverse wrap is priority if both set" {
 
 test "Terminal: cursorLeft extended reverse wrap above top scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10142,7 +10405,8 @@ test "Terminal: cursorLeft extended reverse wrap above top scroll region" {
 
 test "Terminal: cursorLeft reverse wrap on first row" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -10158,7 +10422,8 @@ test "Terminal: cursorLeft reverse wrap on first row" {
 
 test "Terminal: cursorDown basic" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -10174,7 +10439,8 @@ test "Terminal: cursorDown basic" {
 
 test "Terminal: cursorDown above bottom scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -10191,7 +10457,8 @@ test "Terminal: cursorDown above bottom scroll margin" {
 
 test "Terminal: cursorDown below bottom scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setTopAndBottomMargin(1, 3);
@@ -10209,7 +10476,8 @@ test "Terminal: cursorDown below bottom scroll margin" {
 
 test "Terminal: cursorDown resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -10227,7 +10495,8 @@ test "Terminal: cursorDown resets wrap" {
 
 test "Terminal: cursorRight resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -10245,7 +10514,8 @@ test "Terminal: cursorRight resets wrap" {
 
 test "Terminal: cursorRight to the edge of screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.cursorRight(100);
@@ -10260,7 +10530,8 @@ test "Terminal: cursorRight to the edge of screen" {
 
 test "Terminal: cursorRight left of right margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.scrolling_region.right = 2;
@@ -10276,7 +10547,8 @@ test "Terminal: cursorRight left of right margin" {
 
 test "Terminal: cursorRight right of right margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.scrolling_region.right = 2;
@@ -10293,7 +10565,8 @@ test "Terminal: cursorRight right of right margin" {
 
 test "Terminal: deleteLines simple" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -10325,7 +10598,8 @@ test "Terminal: deleteLines simple" {
 
 test "Terminal: deleteLines colors with bg color" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("ABC");
@@ -10366,7 +10640,8 @@ test "Terminal: deleteLines colors with bg color" {
 
 test "Terminal: deleteLines across page boundary marks all shifted rows dirty" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
     defer t.deinit(alloc);
 
     const first_page = t.screens.active.pages.pages.first.?;
@@ -10425,7 +10700,8 @@ test "Terminal: deleteLines hyperlink-dense row crosses page boundary" {
     // the first page, which also happens to be the cursor's page so
     // this exercises the cursor accounting of the capacity increase.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 10, .max_scrollback = 1024 });
     defer t.deinit(alloc);
 
     const pages = &t.screens.active.pages;
@@ -10506,7 +10782,8 @@ test "Terminal: deleteLines hyperlink-dense row crosses page boundary" {
 
 test "Terminal: deleteLines (legacy)" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 80, .rows = 80 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 80, .rows = 80 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10541,7 +10818,8 @@ test "Terminal: deleteLines (legacy)" {
 
 test "Terminal: deleteLines with scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 80, .rows = 80 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 80, .rows = 80 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10584,7 +10862,8 @@ test "Terminal: deleteLines with scroll region" {
 
 test "Terminal: deleteLines with scroll region, large count" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 80, .rows = 80 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 80, .rows = 80 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10627,7 +10906,8 @@ test "Terminal: deleteLines with scroll region, large count" {
 
 test "Terminal: deleteLines with scroll region, cursor outside of region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 80, .rows = 80 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 80, .rows = 80 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10662,7 +10942,8 @@ test "Terminal: deleteLines with scroll region, cursor outside of region" {
 
 test "Terminal: deleteLines resets pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -10680,7 +10961,8 @@ test "Terminal: deleteLines resets pending wrap" {
 
 test "Terminal: deleteLines resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 3, .cols = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     try t.print('1');
@@ -10711,7 +10993,8 @@ test "Terminal: deleteLines resets wrap" {
 
 test "Terminal: deleteLines left/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -10743,7 +11026,8 @@ test "Terminal: deleteLines left/right scroll region" {
 
 test "Terminal: deleteLines left/right scroll region from top" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -10774,7 +11058,8 @@ test "Terminal: deleteLines left/right scroll region from top" {
 
 test "Terminal: deleteLines left/right scroll region high count" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -10806,7 +11091,8 @@ test "Terminal: deleteLines left/right scroll region high count" {
 
 test "Terminal: deleteLines wide character spacer head" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10842,7 +11128,8 @@ test "Terminal: deleteLines wide character spacer head" {
 
 test "Terminal: deleteLines wide character spacer head left scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10883,7 +11170,8 @@ test "Terminal: deleteLines wide character spacer head left scroll margin" {
 
 test "Terminal: deleteLines wide character spacer head right scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10924,7 +11212,8 @@ test "Terminal: deleteLines wide character spacer head right scroll margin" {
 
 test "Terminal: deleteLines wide character spacer head left and right scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -10966,7 +11255,8 @@ test "Terminal: deleteLines wide character spacer head left and right scroll mar
 
 test "Terminal: deleteLines wide character spacer head left (< 2) and right scroll margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 3 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -11008,7 +11298,8 @@ test "Terminal: deleteLines wide character spacer head left (< 2) and right scro
 
 test "Terminal: deleteLines wide characters split by left/right scroll region boundaries" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -11043,7 +11334,8 @@ test "Terminal: deleteLines wide characters split by left/right scroll region bo
 
 test "Terminal: deleteLines zero" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 5 });
     defer t.deinit(alloc);
 
     // This should do nothing
@@ -11053,7 +11345,8 @@ test "Terminal: deleteLines zero" {
 
 test "Terminal: default style is empty" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -11061,14 +11354,15 @@ test "Terminal: default style is empty" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint.data);
         try testing.expectEqual(@as(style.Id, 0), cell.style_id);
     }
 }
 
 test "Terminal: bold style" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.setAttribute(.{ .bold = {} });
@@ -11077,7 +11371,7 @@ test "Terminal: bold style" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'A'), cell.content.codepoint.data);
         try testing.expect(cell.style_id != 0);
         const page = t.screens.active.cursor.page_pin.node.page();
         try testing.expect(page.styles.refCount(page.memory, t.screens.active.cursor.style_id) > 1);
@@ -11086,7 +11380,8 @@ test "Terminal: bold style" {
 
 test "Terminal: garbage collect overwritten" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.setAttribute(.{ .bold = {} });
@@ -11098,7 +11393,7 @@ test "Terminal: garbage collect overwritten" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'B'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'B'), cell.content.codepoint.data);
         try testing.expect(cell.style_id == 0);
     }
 
@@ -11109,7 +11404,8 @@ test "Terminal: garbage collect overwritten" {
 
 test "Terminal: do not garbage collect old styles in use" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.setAttribute(.{ .bold = {} });
@@ -11120,7 +11416,7 @@ test "Terminal: do not garbage collect old styles in use" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 'B'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 'B'), cell.content.codepoint.data);
         try testing.expect(cell.style_id == 0);
     }
 
@@ -11131,7 +11427,8 @@ test "Terminal: do not garbage collect old styles in use" {
 
 test "Terminal: print with style marks the row as styled" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.setAttribute(.{ .bold = {} });
@@ -11147,7 +11444,8 @@ test "Terminal: print with style marks the row as styled" {
 
 test "Terminal: DECALN" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 2 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -11174,7 +11472,8 @@ test "Terminal: DECALN" {
 
 test "Terminal: decaln reset margins" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 3 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -11192,7 +11491,8 @@ test "Terminal: decaln reset margins" {
 
 test "Terminal: decaln preserves color" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 3 });
     defer t.deinit(alloc);
 
     // Initial value
@@ -11221,7 +11521,8 @@ test "Terminal: decaln preserves color" {
 
 test "Terminal: DECALN resets graphemes with protected mode" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 3 });
     defer t.deinit(alloc);
 
     // Add protected mode. A previous version of DECALN accidentally preserved
@@ -11257,7 +11558,8 @@ test "Terminal: DECALN resets graphemes with protected mode" {
 
 test "Terminal: insertBlanks zero" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -11278,7 +11580,8 @@ test "Terminal: insertBlanks" {
     // NOTE: this is not verified with conformance tests, so these
     // tests might actually be verifying wrong behavior.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -11302,7 +11605,8 @@ test "Terminal: insertBlanks pushes off end" {
     // NOTE: this is not verified with conformance tests, so these
     // tests might actually be verifying wrong behavior.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -11325,7 +11629,8 @@ test "Terminal: insertBlanks more than size" {
     // NOTE: this is not verified with conformance tests, so these
     // tests might actually be verifying wrong behavior.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -11346,7 +11651,8 @@ test "Terminal: insertBlanks more than size" {
 
 test "Terminal: insertBlanks no scroll region, fits" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -11365,7 +11671,8 @@ test "Terminal: insertBlanks no scroll region, fits" {
 
 test "Terminal: insertBlanks preserves background sgr" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -11395,7 +11702,8 @@ test "Terminal: insertBlanks preserves background sgr" {
 
 test "Terminal: insertBlanks shift off screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 10 });
     defer t.deinit(alloc);
 
     for ("  ABC") |c| try t.print(c);
@@ -11414,7 +11722,8 @@ test "Terminal: insertBlanks shift off screen" {
 
 test "Terminal: insertBlanks split multi-cell character" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 10 });
     defer t.deinit(alloc);
 
     for ("123") |c| try t.print(c);
@@ -11433,7 +11742,8 @@ test "Terminal: insertBlanks split multi-cell character" {
 
 test "Terminal: insertBlanks inside left/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     t.scrolling_region.left = 2;
@@ -11456,7 +11766,8 @@ test "Terminal: insertBlanks inside left/right scroll region" {
 
 test "Terminal: insertBlanks outside left/right scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 6, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 6, .rows = 10 });
     defer t.deinit(alloc);
 
     t.setCursorPos(1, 4);
@@ -11479,7 +11790,8 @@ test "Terminal: insertBlanks outside left/right scroll region" {
 
 test "Terminal: insertBlanks left/right scroll region large count" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     t.modes.set(.origin, true);
@@ -11500,7 +11812,8 @@ test "Terminal: insertBlanks left/right scroll region large count" {
 
 test "Terminal: insertBlanks deleting graphemes" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Disable grapheme clustering
@@ -11536,7 +11849,8 @@ test "Terminal: insertBlanks deleting graphemes" {
 
 test "Terminal: insertBlanks shift graphemes" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Enable grapheme clustering
@@ -11572,7 +11886,8 @@ test "Terminal: insertBlanks shift graphemes" {
 
 test "Terminal: insertBlanks split multi-cell character from tail" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("橋123");
@@ -11596,7 +11911,8 @@ test "Terminal: insertBlanks shifts hyperlinks" {
     // link should be preserved, blanks should not be linked
 
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -11637,7 +11953,8 @@ test "Terminal: insertBlanks shifts hyperlinks" {
 
 test "Terminal: insertBlanks pushes hyperlink off end completely" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -11673,7 +11990,8 @@ test "Terminal: insertBlanks wide char straddling right margin" {
     // away via swapCells but leaves the orphaned spacer_tail in place,
     // causing a page integrity violation.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Fill row: A B C D 橋 _ _ _ _ _
@@ -11708,7 +12026,8 @@ test "Terminal: insertBlanks wide char spacer_tail orphaned beyond right margin"
     // is left behind, causing a page integrity violation:
     //   "spacer tail not following wide"
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Fill cols 0–9 with wide chars: 中中中中中
@@ -11738,7 +12057,8 @@ test "Terminal: insertBlanks wide char spacer_tail orphaned beyond right margin"
 
 test "Terminal: insert mode with space" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     for ("hello") |c| try t.print(c);
@@ -11755,7 +12075,8 @@ test "Terminal: insert mode with space" {
 
 test "Terminal: insert mode doesn't wrap pushed characters" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     for ("hello") |c| try t.print(c);
@@ -11772,7 +12093,8 @@ test "Terminal: insert mode doesn't wrap pushed characters" {
 
 test "Terminal: insert mode does nothing at the end of the line" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     for ("hello") |c| try t.print(c);
@@ -11788,7 +12110,8 @@ test "Terminal: insert mode does nothing at the end of the line" {
 
 test "Terminal: insert mode with wide characters" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     for ("hello") |c| try t.print(c);
@@ -11805,7 +12128,8 @@ test "Terminal: insert mode with wide characters" {
 
 test "Terminal: insert mode with wide characters at end" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     for ("well") |c| try t.print(c);
@@ -11821,7 +12145,8 @@ test "Terminal: insert mode with wide characters at end" {
 
 test "Terminal: insert mode pushing off wide character" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     for ("123") |c| try t.print(c);
@@ -11839,7 +12164,8 @@ test "Terminal: insert mode pushing off wide character" {
 
 test "Terminal: deleteChars" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -11858,7 +12184,8 @@ test "Terminal: deleteChars" {
 
 test "Terminal: deleteChars zero count" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -11877,7 +12204,8 @@ test "Terminal: deleteChars zero count" {
 
 test "Terminal: deleteChars more than half" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -11896,7 +12224,8 @@ test "Terminal: deleteChars more than half" {
 
 test "Terminal: deleteChars more than line width" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -11915,7 +12244,8 @@ test "Terminal: deleteChars more than line width" {
 
 test "Terminal: deleteChars should shift left" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -11934,7 +12264,8 @@ test "Terminal: deleteChars should shift left" {
 
 test "Terminal: deleteChars resets pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -11952,7 +12283,8 @@ test "Terminal: deleteChars resets pending wrap" {
 
 test "Terminal: deleteChars resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE123") |c| try t.print(c);
@@ -11981,7 +12313,8 @@ test "Terminal: deleteChars resets wrap" {
 
 test "Terminal: deleteChars simple operation" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -12000,7 +12333,8 @@ test "Terminal: deleteChars simple operation" {
 
 test "Terminal: deleteChars preserves background sgr" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     for ("ABC123") |c| try t.print(c);
@@ -12033,7 +12367,8 @@ test "Terminal: deleteChars preserves background sgr" {
 
 test "Terminal: deleteChars outside scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 6, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 6, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -12054,7 +12389,8 @@ test "Terminal: deleteChars outside scroll region" {
 
 test "Terminal: deleteChars inside scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 6, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 6, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("ABC123");
@@ -12075,7 +12411,8 @@ test "Terminal: deleteChars inside scroll region" {
 
 test "Terminal: deleteChars split wide character from spacer tail" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 6, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 6, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("A橋123");
@@ -12091,7 +12428,8 @@ test "Terminal: deleteChars split wide character from spacer tail" {
 
 test "Terminal: deleteChars split wide character from wide" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 6, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 6, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("橋123");
@@ -12101,20 +12439,21 @@ test "Terminal: deleteChars split wide character from wide" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, '1'), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, '1'), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: deleteChars split wide character from end" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 6, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 6, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("A橋123");
@@ -12124,20 +12463,21 @@ test "Terminal: deleteChars split wide character from end" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 0, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0x6A4B), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0x6A4B), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.wide, cell.wide);
     }
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 1, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.spacer_tail, cell.wide);
     }
 }
 
 test "Terminal: deleteChars with a spacer head at the end" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 10 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 10 });
     defer t.deinit(alloc);
 
     try t.printString("0123橋123");
@@ -12155,14 +12495,15 @@ test "Terminal: deleteChars with a spacer head at the end" {
     {
         const list_cell = t.screens.active.pages.getCell(.{ .screen = .{ .x = 3, .y = 0 } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u21, 0), cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), cell.content.codepoint.data);
         try testing.expectEqual(Cell.Wide.narrow, cell.wide);
     }
 }
 
 test "Terminal: deleteChars split wide character tail" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(1, t.cols - 1);
@@ -12180,7 +12521,8 @@ test "Terminal: deleteChars split wide character tail" {
 
 test "Terminal: deleteChars wide char boundary conditions" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 1, .cols = 8 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 1, .cols = 8 });
     defer t.deinit(alloc);
 
     // EXPLANATION(qwerasd):
@@ -12244,7 +12586,8 @@ test "Terminal: deleteChars wide char boundary conditions" {
 
 test "Terminal: deleteChars wide char wrap boundary conditions" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 3, .cols = 8 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 3, .cols = 8 });
     defer t.deinit(alloc);
 
     // EXPLANATION(qwerasd):
@@ -12300,7 +12643,8 @@ test "Terminal: deleteChars wide char wrap boundary conditions" {
 
 test "Terminal: deleteChars wide char across right margin" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 3, .cols = 8 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 3, .cols = 8 });
     defer t.deinit(alloc);
 
     // scroll region
@@ -12343,7 +12687,8 @@ test "Terminal: deleteChars wide char across right margin" {
 
 test "Terminal: saveCursor" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 3 });
     defer t.deinit(alloc);
 
     try t.setAttribute(.{ .bold = {} });
@@ -12361,7 +12706,8 @@ test "Terminal: saveCursor" {
 
 test "Terminal: saveCursor position" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(1, 5);
@@ -12381,7 +12727,8 @@ test "Terminal: saveCursor position" {
 
 test "Terminal: saveCursor pending wrap state" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(1, 5);
@@ -12401,7 +12748,8 @@ test "Terminal: saveCursor pending wrap state" {
 
 test "Terminal: saveCursor origin mode" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.origin, true);
@@ -12421,7 +12769,8 @@ test "Terminal: saveCursor origin mode" {
 
 test "Terminal: saveCursor resize" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setCursorPos(1, 10);
@@ -12439,7 +12788,8 @@ test "Terminal: saveCursor resize" {
 
 test "Terminal: saveCursor protected pen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -12454,7 +12804,8 @@ test "Terminal: saveCursor protected pen" {
 
 test "Terminal: saveCursor doesn't modify hyperlink state" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 3 });
     defer t.deinit(alloc);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -12470,9 +12821,10 @@ test "Terminal: restoreCursor uses default style on OutOfSpace" {
     // manualStyleUpdate fails with OutOfSpace (can't split a 1-row page
     // and styles are at max capacity).
     const alloc = testing.allocator;
+    const io_impl = testing.io;
 
     // Use a single row so the page can't be split
-    var t = try init(alloc, .{ .cols = 10, .rows = 1 });
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 1 });
     defer t.deinit(alloc);
 
     // Set a style and save the cursor
@@ -12524,7 +12876,8 @@ test "Terminal: restoreCursor uses default style on OutOfSpace" {
 
 test "Terminal: setProtectedMode" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 3 });
     defer t.deinit(alloc);
 
     try testing.expect(!t.screens.active.cursor.protected);
@@ -12540,7 +12893,8 @@ test "Terminal: setProtectedMode" {
 
 test "Terminal: eraseLine simple erase right" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -12558,7 +12912,8 @@ test "Terminal: eraseLine simple erase right" {
 
 test "Terminal: eraseLine resets pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -12576,7 +12931,8 @@ test "Terminal: eraseLine resets pending wrap" {
 
 test "Terminal: eraseLine resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE123") |c| try t.print(c);
@@ -12603,7 +12959,8 @@ test "Terminal: eraseLine resets wrap" {
 
 test "Terminal: eraseLine right preserves background sgr" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -12636,7 +12993,8 @@ test "Terminal: eraseLine right preserves background sgr" {
 
 test "Terminal: eraseLine right wide character" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     for ("AB") |c| try t.print(c);
@@ -12656,7 +13014,8 @@ test "Terminal: eraseLine right wide character" {
 
 test "Terminal: eraseLine right protected attributes respected with iso" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -12675,7 +13034,8 @@ test "Terminal: eraseLine right protected attributes respected with iso" {
 
 test "Terminal: eraseLine right protected attributes ignored with dec most recent" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -12696,7 +13056,8 @@ test "Terminal: eraseLine right protected attributes ignored with dec most recen
 
 test "Terminal: eraseLine right protected attributes ignored with dec set" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -12715,7 +13076,8 @@ test "Terminal: eraseLine right protected attributes ignored with dec set" {
 
 test "Terminal: eraseLine right protected requested" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     for ("12345678") |c| try t.print(c);
@@ -12736,7 +13098,8 @@ test "Terminal: eraseLine right protected requested" {
 
 test "Terminal: eraseLine simple erase left" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -12754,7 +13117,8 @@ test "Terminal: eraseLine simple erase left" {
 
 test "Terminal: eraseLine left resets wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -12774,7 +13138,8 @@ test "Terminal: eraseLine left resets wrap" {
 
 test "Terminal: eraseLine left preserves background sgr" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -12807,7 +13172,8 @@ test "Terminal: eraseLine left preserves background sgr" {
 
 test "Terminal: eraseLine left wide character" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     for ("AB") |c| try t.print(c);
@@ -12827,7 +13193,8 @@ test "Terminal: eraseLine left wide character" {
 
 test "Terminal: eraseLine left protected attributes respected with iso" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -12846,7 +13213,8 @@ test "Terminal: eraseLine left protected attributes respected with iso" {
 
 test "Terminal: eraseLine left protected attributes ignored with dec most recent" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -12867,7 +13235,8 @@ test "Terminal: eraseLine left protected attributes ignored with dec most recent
 
 test "Terminal: eraseLine left protected attributes ignored with dec set" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -12886,7 +13255,8 @@ test "Terminal: eraseLine left protected attributes ignored with dec set" {
 
 test "Terminal: eraseLine left protected requested" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     for ("123456789") |c| try t.print(c);
@@ -12907,7 +13277,8 @@ test "Terminal: eraseLine left protected requested" {
 
 test "Terminal: eraseLine complete preserves background sgr" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -12940,7 +13311,8 @@ test "Terminal: eraseLine complete preserves background sgr" {
 
 test "Terminal: eraseLine complete protected attributes respected with iso" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -12959,7 +13331,8 @@ test "Terminal: eraseLine complete protected attributes respected with iso" {
 
 test "Terminal: eraseLine complete protected attributes ignored with dec most recent" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -12980,7 +13353,8 @@ test "Terminal: eraseLine complete protected attributes ignored with dec most re
 
 test "Terminal: eraseLine complete protected attributes ignored with dec set" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -12999,7 +13373,8 @@ test "Terminal: eraseLine complete protected attributes ignored with dec set" {
 
 test "Terminal: eraseLine complete protected requested" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     for ("123456789") |c| try t.print(c);
@@ -13020,7 +13395,8 @@ test "Terminal: eraseLine complete protected requested" {
 
 test "Terminal: tabClear single" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 30, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 30, .rows = 5 });
     defer t.deinit(alloc);
 
     t.horizontalTab();
@@ -13033,7 +13409,8 @@ test "Terminal: tabClear single" {
 
 test "Terminal: tabClear all" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 30, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 30, .rows = 5 });
     defer t.deinit(alloc);
 
     t.tabClear(.all);
@@ -13045,7 +13422,8 @@ test "Terminal: tabClear all" {
 
 test "Terminal: printRepeat simple" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("A");
@@ -13061,7 +13439,8 @@ test "Terminal: printRepeat simple" {
 
 test "Terminal: printRepeat wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("    A");
@@ -13077,7 +13456,8 @@ test "Terminal: printRepeat wrap" {
 
 test "Terminal: printRepeat no previous character" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printRepeat(1);
@@ -13092,7 +13472,8 @@ test "Terminal: printRepeat no previous character" {
 
 test "Terminal: printSlice simple ascii" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     try t.printSlice(&.{ 'h', 'e', 'l', 'l', 'o' });
@@ -13109,7 +13490,8 @@ test "Terminal: printSlice simple ascii" {
 
 test "Terminal: printSlice wraps and scrolls" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     // 12 chars: fills row 1 (5), row 2 (5), wraps+scrolls, 2 more.
@@ -13126,7 +13508,8 @@ test "Terminal: printSlice wraps and scrolls" {
 
 test "Terminal: printSlice pending wrap state" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 5, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 5, .rows = 2 });
     defer t.deinit(alloc);
 
     try t.printSlice(&.{ 'a', 'b', 'c', 'd', 'e' });
@@ -13145,18 +13528,19 @@ test "Terminal: printSlice pending wrap state" {
 /// the other using printSlice() with random chunking, verifying that
 /// the results are identical.
 fn testPrintSliceDifferential(
+    io_impl: std.Io,
     alloc: Allocator,
     rand: std.Random,
     ops: usize,
     cols: size.CellCountInt,
     rows: size.CellCountInt,
 ) !void {
-    var t1 = try init(alloc, .{
+    var t1 = try init(io_impl, alloc, .{
         .cols = cols,
         .rows = rows,
     });
     defer t1.deinit(alloc);
-    var t2 = try init(alloc, .{
+    var t2 = try init(io_impl, alloc, .{
         .cols = cols,
         .rows = rows,
     });
@@ -13165,11 +13549,12 @@ fn testPrintSliceDifferential(
     // Alphabet of interesting codepoints: ascii, latin-1, combining
     // marks, CJK (wide), emoji (wide), ZWJ, variation selectors.
     const alphabet = [_]u21{
-        'a',     'b',     'Z',     '0',    ' ',    0x10,    0x1F,   0x7F,
-        'é',    0xFF,    0x301,   0x4E00, 0x4E01, 0x1F600, 0x200D, 0xFE0F,
-        'x',     'y',     0x1F9D1, 0x0308, 0xAD,   0x3042,  0xAC00, 'q',
-        'r',     's',     't',     'u',    'v',    'w',     '1',    '2',
-        0x1F1E6, 0x1F1E7, 0x1100,  0x1161, 0x11A8, 0x200C,  0x0430, 0x03B1,
+        'a',     'b',     'Z',    '0',    ' ',     0x10,   0x1F,   0x7F,
+        'é',
+        0xFF,    0x301,   0x4E00, 0x4E01, 0x1F600, 0x200D, 0xFE0F, 'x',
+        'y',     0x1F9D1, 0x0308, 0xAD,   0x3042,  0xAC00, 'q',    'r',
+        's',     't',     'u',    'v',    'w',     '1',    '2',    0x1F1E6,
+        0x1F1E7, 0x1100,  0x1161, 0x11A8, 0x200C,  0x0430, 0x03B1,
     };
 
     var cps_buf: [64]u32 = undefined;
@@ -13307,20 +13692,22 @@ fn testPrintSliceDifferential(
 
 test "Terminal: printSlice differential fuzz vs print" {
     const alloc = testing.allocator;
+    const io_impl = testing.io;
 
     // Multiple seeds and terminal sizes for coverage, including a
     // tiny terminal to stress wrap/scroll edge cases.
     var prng = std.Random.DefaultPrng.init(0xC0FFEE);
     const rand = prng.random();
-    try testPrintSliceDifferential(alloc, rand, 500, 80, 24);
-    try testPrintSliceDifferential(alloc, rand, 500, 10, 4);
-    try testPrintSliceDifferential(alloc, rand, 500, 5, 2);
-    try testPrintSliceDifferential(alloc, rand, 200, 2, 2);
+    try testPrintSliceDifferential(io_impl, alloc, rand, 500, 80, 24);
+    try testPrintSliceDifferential(io_impl, alloc, rand, 500, 10, 4);
+    try testPrintSliceDifferential(io_impl, alloc, rand, 500, 5, 2);
+    try testPrintSliceDifferential(io_impl, alloc, rand, 200, 2, 2);
 }
 
 test "Terminal: printAttributes" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     var storage: [64]u8 = undefined;
@@ -13371,7 +13758,8 @@ test "Terminal: printAttributes" {
 
 test "Terminal: eraseDisplay simple erase below" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -13399,7 +13787,8 @@ test "Terminal: eraseDisplay simple erase below" {
 
 test "Terminal: eraseDisplay erase below preserves SGR bg" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -13439,7 +13828,8 @@ test "Terminal: eraseDisplay erase below preserves SGR bg" {
 
 test "Terminal: eraseDisplay below split multi-cell" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("AB橋C");
@@ -13461,7 +13851,8 @@ test "Terminal: eraseDisplay below split multi-cell" {
 
 test "Terminal: eraseDisplay below protected attributes respected with iso" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -13484,7 +13875,8 @@ test "Terminal: eraseDisplay below protected attributes respected with iso" {
 
 test "Terminal: eraseDisplay below protected attributes ignored with dec most recent" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -13509,7 +13901,8 @@ test "Terminal: eraseDisplay below protected attributes ignored with dec most re
 
 test "Terminal: eraseDisplay below protected attributes ignored with dec set" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -13532,7 +13925,8 @@ test "Terminal: eraseDisplay below protected attributes ignored with dec set" {
 
 test "Terminal: eraseDisplay below protected attributes respected with force" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -13555,7 +13949,8 @@ test "Terminal: eraseDisplay below protected attributes respected with force" {
 
 test "Terminal: eraseDisplay simple erase above" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -13582,7 +13977,8 @@ test "Terminal: eraseDisplay simple erase above" {
 
 test "Terminal: eraseDisplay erase above preserves SGR bg" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABC") |c| try t.print(c);
@@ -13622,7 +14018,8 @@ test "Terminal: eraseDisplay erase above preserves SGR bg" {
 
 test "Terminal: eraseDisplay above split multi-cell" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.printString("AB橋C");
@@ -13644,7 +14041,8 @@ test "Terminal: eraseDisplay above split multi-cell" {
 
 test "Terminal: eraseDisplay above protected attributes respected with iso" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -13667,7 +14065,8 @@ test "Terminal: eraseDisplay above protected attributes respected with iso" {
 
 test "Terminal: eraseDisplay above protected attributes ignored with dec most recent" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.iso);
@@ -13692,7 +14091,8 @@ test "Terminal: eraseDisplay above protected attributes ignored with dec most re
 
 test "Terminal: eraseDisplay above protected attributes ignored with dec set" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -13715,7 +14115,8 @@ test "Terminal: eraseDisplay above protected attributes ignored with dec set" {
 
 test "Terminal: eraseDisplay above protected attributes respected with force" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.setProtectedMode(.dec);
@@ -13738,7 +14139,8 @@ test "Terminal: eraseDisplay above protected attributes respected with force" {
 
 test "Terminal: eraseDisplay protected complete" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -13766,7 +14168,8 @@ test "Terminal: eraseDisplay protected complete" {
 
 test "Terminal: eraseDisplay protected below" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -13788,7 +14191,8 @@ test "Terminal: eraseDisplay protected below" {
 
 test "Terminal: eraseDisplay scroll complete" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -13805,7 +14209,8 @@ test "Terminal: eraseDisplay scroll complete" {
 
 test "Terminal: eraseDisplay protected above" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     try t.print('A');
@@ -13827,7 +14232,8 @@ test "Terminal: eraseDisplay protected above" {
 
 test "Terminal: eraseDisplay complete preserves cursor" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Set our cursur
@@ -13844,7 +14250,8 @@ test "Terminal: eraseDisplay complete preserves cursor" {
 
 test "Terminal: semantic prompt" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Prompt
@@ -13888,7 +14295,8 @@ test "Terminal: semantic prompt" {
 
 test "Terminal: semantic prompt continuations" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Prompt
@@ -13938,7 +14346,8 @@ test "Terminal: index in prompt mode marks new row as prompt continuation" {
     // a newline, assume the new row is a prompt continuation (since Fish
     // doesn't emit OSC133 k=s markers for continuation lines).
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Start a prompt
@@ -13975,7 +14384,8 @@ test "Terminal: index in input mode does not mark new row as prompt" {
     // Input mode should NOT trigger prompt continuation on newline
     // (only prompt mode does, not input mode)
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Start a prompt then switch to input
@@ -14004,7 +14414,8 @@ test "Terminal: index in input mode does not mark new row as prompt" {
 test "Terminal: index in output mode does not mark new row as prompt" {
     // Output mode should NOT trigger prompt continuation
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Complete prompt cycle: prompt -> input -> output
@@ -14033,7 +14444,8 @@ test "Terminal: OSC133C at x=0 on prompt row clears prompt mark" {
     // then immediately sends OSC133C (start output) at column 0, we
     // should clear the prompt continuation mark we just set.
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Start a prompt
@@ -14070,7 +14482,8 @@ test "Terminal: OSC133C at x=0 on prompt row clears prompt mark" {
 test "Terminal: OSC133C at x>0 on prompt row does not clear prompt mark" {
     // If we're not at column 0, we shouldn't clear the prompt mark
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Start a prompt on a row
@@ -14112,7 +14525,8 @@ test "Terminal: OSC133C at x>0 on prompt row does not clear prompt mark" {
 test "Terminal: multiple newlines in prompt mode marks all rows" {
     // Multiple newlines should each mark their row as prompt continuation
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Start a prompt
@@ -14155,7 +14569,8 @@ test "Terminal: multiple newlines in prompt mode marks all rows" {
 
 test "Terminal: OSC133A click_events=1 sets click to click_events" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Verify default state is none
@@ -14172,7 +14587,8 @@ test "Terminal: OSC133A click_events=1 sets click to click_events" {
 
 test "Terminal: OSC133A click_events=2 sets click to click_events (relative)" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // Verify default state is none
@@ -14189,7 +14605,8 @@ test "Terminal: OSC133A click_events=2 sets click to click_events (relative)" {
 
 test "Terminal: OSC133A click_events=0 does not set click_events" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // OSC 133;A with click_events=0
@@ -14204,7 +14621,8 @@ test "Terminal: OSC133A click_events=0 does not set click_events" {
 
 test "Terminal: OSC133A cl option sets click to cl value" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // OSC 133;A with cl=m (multiple)
@@ -14218,7 +14636,8 @@ test "Terminal: OSC133A cl option sets click to cl value" {
 
 test "Terminal: OSC133A cl=line sets click to line" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     try t.semanticPrompt(.{
@@ -14231,7 +14650,8 @@ test "Terminal: OSC133A cl=line sets click to line" {
 
 test "Terminal: OSC133A click_events=1 takes priority over cl" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // OSC 133;A with both click_events=1 and cl=m
@@ -14246,7 +14666,8 @@ test "Terminal: OSC133A click_events=1 takes priority over cl" {
 
 test "Terminal: OSC133A click_events=0 falls back to cl" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // OSC 133;A with click_events=0 and cl=v
@@ -14261,7 +14682,8 @@ test "Terminal: OSC133A click_events=0 falls back to cl" {
 
 test "Terminal: OSC133A no click options leaves click as none" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     // OSC 133;A with no click-related options
@@ -14275,7 +14697,8 @@ test "Terminal: OSC133A no click options leaves click as none" {
 
 test "Terminal: cursorIsAtPrompt" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 10, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 10, .rows = 3 });
     defer t.deinit(alloc);
 
     try testing.expect(!t.cursorIsAtPrompt());
@@ -14304,7 +14727,8 @@ test "Terminal: cursorIsAtPrompt" {
 
 test "Terminal: cursorIsAtPrompt alternate screen" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 2 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 2 });
     defer t.deinit(alloc);
 
     try testing.expect(!t.cursorIsAtPrompt());
@@ -14319,7 +14743,7 @@ test "Terminal: cursorIsAtPrompt alternate screen" {
 }
 
 test "Terminal: cursor defaults update current default cursor" {
-    var t = try init(testing.allocator, .{
+    var t = try init(testing.io, testing.allocator, .{
         .cols = 10,
         .rows = 10,
         .default_cursor_style = .bar,
@@ -14346,7 +14770,7 @@ test "Terminal: cursor defaults update current default cursor" {
 }
 
 test "Terminal: cursor defaults do not override explicit cursor" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     t.setCursorStyle(.blinking_bar);
@@ -14377,7 +14801,7 @@ test "Terminal: cursor defaults do not override explicit cursor" {
 }
 
 test "Terminal: fullReset with a non-empty pen" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.setAttribute(.{ .direct_color_fg = .{ .r = 0xFF, .g = 0, .b = 0x7F } });
@@ -14399,7 +14823,7 @@ test "Terminal: fullReset with a non-empty pen" {
 }
 
 test "Terminal: fullReset hyperlink" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.screens.active.startHyperlink("http://example.com", null);
@@ -14408,7 +14832,7 @@ test "Terminal: fullReset hyperlink" {
 }
 
 test "Terminal: fullReset with a non-empty saved cursor" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     try t.setAttribute(.{ .direct_color_fg = .{ .r = 0xFF, .g = 0, .b = 0x7F } });
@@ -14429,7 +14853,7 @@ test "Terminal: fullReset with a non-empty saved cursor" {
 }
 
 test "Terminal: fullReset origin mode" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     t.setCursorPos(3, 5);
@@ -14443,7 +14867,7 @@ test "Terminal: fullReset origin mode" {
 }
 
 test "Terminal: fullReset status display" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     t.status_display = .status_line;
@@ -14453,7 +14877,7 @@ test "Terminal: fullReset status display" {
 
 // https://github.com/mitchellh/ghostty/issues/1607
 test "Terminal: fullReset clears alt screen kitty keyboard state" {
-    var t = try init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     try t.switchScreenMode(.@"1049", true);
@@ -14471,7 +14895,7 @@ test "Terminal: fullReset clears alt screen kitty keyboard state" {
 }
 
 test "Terminal: fullReset default modes" {
-    var t = try init(testing.allocator, .{
+    var t = try init(testing.io, testing.allocator, .{
         .cols = 10,
         .rows = 10,
         .default_modes = .{ .grapheme_cluster = true },
@@ -14483,7 +14907,7 @@ test "Terminal: fullReset default modes" {
 }
 
 test "Terminal: fullReset tracked pins" {
-    var t = try init(testing.allocator, .{ .cols = 80, .rows = 80 });
+    var t = try init(testing.io, testing.allocator, .{ .cols = 80, .rows = 80 });
     defer t.deinit(testing.allocator);
 
     // Create a tracked pin
@@ -14497,7 +14921,8 @@ test "Terminal: fullReset tracked pins" {
 // this test around to ensure we don't regress at multiple layers.
 test "Terminal: resize less cols with wide char then print" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 3, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 3, .rows = 3 });
     defer t.deinit(alloc);
 
     try t.print('x');
@@ -14511,9 +14936,10 @@ test "Terminal: resize less cols with wide char then print" {
 // This was found via fuzzing so its highly specific.
 test "Terminal: resize with left and right margin set" {
     const alloc = testing.allocator;
+    const io_impl = testing.io;
     const cols = 70;
     const rows = 23;
-    var t = try init(alloc, .{ .cols = cols, .rows = rows });
+    var t = try init(io_impl, alloc, .{ .cols = cols, .rows = rows });
     defer t.deinit(alloc);
 
     t.modes.set(.enable_left_and_right_margin, true);
@@ -14529,9 +14955,10 @@ test "Terminal: resize with left and right margin set" {
 // https://github.com/mitchellh/ghostty/issues/1343
 test "Terminal: resize with wraparound off" {
     const alloc = testing.allocator;
+    const io_impl = testing.io;
     const cols = 4;
     const rows = 2;
-    var t = try init(alloc, .{ .cols = cols, .rows = rows });
+    var t = try init(io_impl, alloc, .{ .cols = cols, .rows = rows });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, false);
@@ -14549,9 +14976,10 @@ test "Terminal: resize with wraparound off" {
 
 test "Terminal: resize with wraparound on" {
     const alloc = testing.allocator;
+    const io_impl = testing.io;
     const cols = 4;
     const rows = 2;
-    var t = try init(alloc, .{ .cols = cols, .rows = rows });
+    var t = try init(io_impl, alloc, .{ .cols = cols, .rows = rows });
     defer t.deinit(alloc);
 
     t.modes.set(.wraparound, true);
@@ -14569,7 +14997,8 @@ test "Terminal: resize with wraparound on" {
 
 test "Terminal: resize with high unique style per cell" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 30, .rows = 30 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 30, .rows = 30 });
     defer t.deinit(alloc);
 
     for (0..t.rows) |y| {
@@ -14589,7 +15018,8 @@ test "Terminal: resize with high unique style per cell" {
 
 test "Terminal: resize with high unique style per cell with wrapping" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 30, .rows = 30 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 30, .rows = 30 });
     defer t.deinit(alloc);
 
     const cell_count: u16 = @intCast(t.rows * t.cols);
@@ -14610,7 +15040,8 @@ test "Terminal: resize with high unique style per cell with wrapping" {
 
 test "Terminal: resize with reflow and saved cursor" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 3 });
     defer t.deinit(alloc);
     try t.printString("1A2B");
     t.setCursorPos(2, 2);
@@ -14620,7 +15051,7 @@ test "Terminal: resize with reflow and saved cursor" {
             .y = t.screens.active.cursor.y,
         } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u32, 'B'), cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'B'), cell.content.codepoint.data);
     }
 
     {
@@ -14646,13 +15077,14 @@ test "Terminal: resize with reflow and saved cursor" {
             .y = t.screens.active.cursor.y,
         } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u32, 'B'), cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'B'), cell.content.codepoint.data);
     }
 }
 
 test "Terminal: resize with reflow and saved cursor pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 2, .rows = 3 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 2, .rows = 3 });
     defer t.deinit(alloc);
     try t.printString("1A2B");
     {
@@ -14661,7 +15093,7 @@ test "Terminal: resize with reflow and saved cursor pending wrap" {
             .y = t.screens.active.cursor.y,
         } }).?;
         const cell = list_cell.cell;
-        try testing.expectEqual(@as(u32, 'B'), cell.content.codepoint);
+        try testing.expectEqual(@as(u32, 'B'), cell.content.codepoint.data);
     }
 
     {
@@ -14691,7 +15123,8 @@ test "Terminal: resize with reflow and saved cursor pending wrap" {
 
 test "Terminal: DECCOLM without DEC mode 40" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.@"132_column", true);
@@ -14703,7 +15136,8 @@ test "Terminal: DECCOLM without DEC mode 40" {
 
 test "Terminal: DECCOLM unset" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.enable_mode_3, true);
@@ -14714,7 +15148,8 @@ test "Terminal: DECCOLM unset" {
 
 test "Terminal: DECCOLM resets pending wrap" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     for ("ABCDE") |c| try t.print(c);
@@ -14729,7 +15164,8 @@ test "Terminal: DECCOLM resets pending wrap" {
 
 test "Terminal: DECCOLM preserves SGR bg" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     try t.setAttribute(.{ .direct_color_bg = .{
@@ -14753,7 +15189,8 @@ test "Terminal: DECCOLM preserves SGR bg" {
 
 test "Terminal: DECCOLM resets scroll region" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     t.modes.set(.enable_left_and_right_margin, true);
@@ -14772,7 +15209,8 @@ test "Terminal: DECCOLM resets scroll region" {
 
 test "Terminal: mode 47 alt screen plain" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Print on primary screen
@@ -14823,7 +15261,8 @@ test "Terminal: mode 47 alt screen plain" {
 
 test "Terminal: mode 47 copies cursor both directions" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Color our cursor red
@@ -14859,7 +15298,8 @@ test "Terminal: mode 47 copies cursor both directions" {
 
 test "Terminal: mode 1047 alt screen plain" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Print on primary screen
@@ -14910,7 +15350,8 @@ test "Terminal: mode 1047 alt screen plain" {
 
 test "Terminal: mode 1047 copies cursor both directions" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Color our cursor red
@@ -14946,7 +15387,8 @@ test "Terminal: mode 1047 copies cursor both directions" {
 
 test "Terminal: mode 1049 alt screen plain" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .rows = 5, .cols = 5 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Print on primary screen
@@ -15011,7 +15453,8 @@ test "Terminal: mode 1049 alt screen plain" {
 // characters straddling the right margin boundary leave orphaned spacer_tails.
 test "Terminal: deleteLines wide char at right margin with full clear" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 80, .rows = 24 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 80, .rows = 24 });
     defer t.deinit(alloc);
 
     // Place a wide character at col 39 (1-indexed) on several rows.
@@ -15034,7 +15477,8 @@ test "Terminal: deleteLines wide char at right margin with full clear" {
 
 test "Terminal: glyph APC stores session glossary entries" {
     const alloc = testing.allocator;
-    var t = try init(alloc, .{ .cols = 80, .rows = 24 });
+    const io_impl = testing.io;
+    var t = try init(io_impl, alloc, .{ .cols = 80, .rows = 24 });
     defer t.deinit(alloc);
 
     var register_parser = glyph.CommandParser.init(alloc, 1024 * 1024);
diff --git a/src/terminal/apc/glyph/request.zig b/src/terminal/apc/glyph/request.zig
index 71a2dd4bf..a45feca28 100644
--- a/src/terminal/apc/glyph/request.zig
+++ b/src/terminal/apc/glyph/request.zig
@@ -305,6 +305,7 @@ pub const Request = union(enum) {
                 error.CompositeNotSupported => error.CompositeUnsupported,
                 error.InstructionsNotSupported => error.HintingUnsupported,
                 // Various semantic issues
+                error.ReadFailed,
                 error.EndOfStream,
                 error.EndPointsOutOfOrder,
                 error.TooManyPoints,
diff --git a/src/terminal/c/build_info.zig b/src/terminal/c/build_info.zig
index 8e0cd4d6c..a186163a5 100644
--- a/src/terminal/c/build_info.zig
+++ b/src/terminal/c/build_info.zig
@@ -45,7 +45,7 @@ pub fn get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(BuildInfo, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(BuildInfo, @intFromEnum(data)) orelse {
             log.warn("build_info invalid data value={d}", .{@intFromEnum(data)});
             return .invalid_value;
         };
diff --git a/src/terminal/c/cell.zig b/src/terminal/c/cell.zig
index b59567dff..cb76cb2fd 100644
--- a/src/terminal/c/cell.zig
+++ b/src/terminal/c/cell.zig
@@ -105,7 +105,7 @@ pub fn get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(CellData, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(CellData, @intFromEnum(data)) orelse {
             return .invalid_value;
         };
     }
@@ -158,7 +158,7 @@ fn getTyped(
         .has_hyperlink => out.* = cell.hyperlink,
         .protected => out.* = cell.protected,
         .semantic_content => out.* = @enumFromInt(@intFromEnum(cell.semantic_content)),
-        .color_palette => out.* = cell.content.color_palette,
+        .color_palette => out.* = cell.content.color_palette.data,
         .color_rgb => {
             const rgb = cell.content.color_rgb;
             out.* = .{ .r = rgb.r, .g = rgb.g, .b = rgb.b };
diff --git a/src/terminal/c/key_encode.zig b/src/terminal/c/key_encode.zig
index f5d459f01..f270cb15a 100644
--- a/src/terminal/c/key_encode.zig
+++ b/src/terminal/c/key_encode.zig
@@ -80,7 +80,7 @@ pub fn setopt(
     value: ?*const anyopaque,
 ) callconv(lib.calling_conv) void {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Option, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(Option, @intFromEnum(option)) orelse {
             log.warn("setopt invalid option value={d}", .{@intFromEnum(option)});
             return;
         };
@@ -113,7 +113,7 @@ fn setoptTyped(
         },
         .macos_option_as_alt => {
             if (comptime std.debug.runtime_safety) {
-                _ = std.meta.intToEnum(OptionAsAlt, @intFromEnum(value.*)) catch {
+                _ = std.enums.fromInt(OptionAsAlt, @intFromEnum(value.*)) orelse {
                     log.warn("setopt invalid OptionAsAlt value={d}", .{@intFromEnum(value.*)});
                     return;
                 };
diff --git a/src/terminal/c/key_event.zig b/src/terminal/c/key_event.zig
index 1feac9ac5..b9deecc6a 100644
--- a/src/terminal/c/key_event.zig
+++ b/src/terminal/c/key_event.zig
@@ -38,7 +38,7 @@ pub fn free(event_: Event) callconv(lib.calling_conv) void {
 
 pub fn set_action(event_: Event, action: key.Action) callconv(lib.calling_conv) void {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(key.Action, @intFromEnum(action)) catch {
+        _ = std.enums.fromInt(key.Action, @intFromEnum(action)) orelse {
             log.warn("set_action invalid action value={d}", .{@intFromEnum(action)});
             return;
         };
@@ -55,7 +55,7 @@ pub fn get_action(event_: Event) callconv(lib.calling_conv) key.Action {
 
 pub fn set_key(event_: Event, k: key.Key) callconv(lib.calling_conv) void {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(key.Key, @intFromEnum(k)) catch {
+        _ = std.enums.fromInt(key.Key, @intFromEnum(k)) orelse {
             log.warn("set_key invalid key value={d}", .{@intFromEnum(k)});
             return;
         };
diff --git a/src/terminal/c/kitty_graphics.zig b/src/terminal/c/kitty_graphics.zig
index 13a675ccc..626cc7703 100644
--- a/src/terminal/c/kitty_graphics.zig
+++ b/src/terminal/c/kitty_graphics.zig
@@ -301,7 +301,7 @@ pub fn placement_iterator_set(
     if (comptime !build_options.kitty_graphics) return .no_value;
 
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(PlacementIteratorOption, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(PlacementIteratorOption, @intFromEnum(option)) orelse {
             return .invalid_value;
         };
     }
diff --git a/src/terminal/c/modes.zig b/src/terminal/c/modes.zig
index 449ce63e3..b249b2a51 100644
--- a/src/terminal/c/modes.zig
+++ b/src/terminal/c/modes.zig
@@ -8,10 +8,10 @@ pub const ReportState = enum(c_int) {
     _,
 
     fn toZig(self: ReportState) ?modes.Report.State {
-        return std.meta.intToEnum(
+        return std.enums.fromInt(
             modes.Report.State,
             @intFromEnum(self),
-        ) catch null;
+        );
     }
 };
 
diff --git a/src/terminal/c/mouse_encode.zig b/src/terminal/c/mouse_encode.zig
index 331dd6060..951e80295 100644
--- a/src/terminal/c/mouse_encode.zig
+++ b/src/terminal/c/mouse_encode.zig
@@ -113,7 +113,7 @@ pub fn setopt(
     value: ?*const anyopaque,
 ) callconv(lib.calling_conv) void {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Option, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(Option, @intFromEnum(option)) orelse {
             log.warn("setopt invalid option value={d}", .{@intFromEnum(option)});
             return;
         };
@@ -137,7 +137,7 @@ fn setoptTyped(
     switch (option) {
         .event => {
             if (comptime std.debug.runtime_safety) {
-                _ = std.meta.intToEnum(TrackingMode, @intFromEnum(value.*)) catch {
+                _ = std.enums.fromInt(TrackingMode, @intFromEnum(value.*)) orelse {
                     log.warn("setopt invalid TrackingMode value={d}", .{@intFromEnum(value.*)});
                     return;
                 };
@@ -149,7 +149,7 @@ fn setoptTyped(
 
         .format => {
             if (comptime std.debug.runtime_safety) {
-                _ = std.meta.intToEnum(Format, @intFromEnum(value.*)) catch {
+                _ = std.enums.fromInt(Format, @intFromEnum(value.*)) orelse {
                     log.warn("setopt invalid Format value={d}", .{@intFromEnum(value.*)});
                     return;
                 };
diff --git a/src/terminal/c/mouse_event.zig b/src/terminal/c/mouse_event.zig
index b3c19dd39..b97b4661a 100644
--- a/src/terminal/c/mouse_event.zig
+++ b/src/terminal/c/mouse_event.zig
@@ -51,7 +51,7 @@ pub fn free(event_: Event) callconv(lib.calling_conv) void {
 
 pub fn set_action(event_: Event, action: Action) callconv(lib.calling_conv) void {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Action, @intFromEnum(action)) catch {
+        _ = std.enums.fromInt(Action, @intFromEnum(action)) orelse {
             log.warn("set_action invalid action value={d}", .{@intFromEnum(action)});
             return;
         };
@@ -66,7 +66,7 @@ pub fn get_action(event_: Event) callconv(lib.calling_conv) Action {
 
 pub fn set_button(event_: Event, button: Button) callconv(lib.calling_conv) void {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Button, @intFromEnum(button)) catch {
+        _ = std.enums.fromInt(Button, @intFromEnum(button)) orelse {
             log.warn("set_button invalid button value={d}", .{@intFromEnum(button)});
             return;
         };
diff --git a/src/terminal/c/osc.zig b/src/terminal/c/osc.zig
index 7ba323001..8eca343c2 100644
--- a/src/terminal/c/osc.zig
+++ b/src/terminal/c/osc.zig
@@ -69,7 +69,7 @@ pub fn commandData(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) bool {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(CommandData, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(CommandData, @intFromEnum(data)) orelse {
             log.warn("commandData invalid data value={d}", .{@intFromEnum(data)});
             return false;
         };
diff --git a/src/terminal/c/render.zig b/src/terminal/c/render.zig
index 6cf78ec54..8ca58475f 100644
--- a/src/terminal/c/render.zig
+++ b/src/terminal/c/render.zig
@@ -213,7 +213,7 @@ pub fn get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Data, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(Data, @intFromEnum(data)) orelse {
             log.warn("render_state_get invalid data value={d}", .{@intFromEnum(data)});
             return .invalid_value;
         };
@@ -310,7 +310,7 @@ pub fn set(
     value: ?*const anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(SetOption, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(SetOption, @intFromEnum(option)) orelse {
             log.warn("render_state_set invalid option value={d}", .{@intFromEnum(option)});
             return .invalid_value;
         };
@@ -509,7 +509,7 @@ pub fn row_cells_get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(RowCellsData, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(RowCellsData, @intFromEnum(data)) orelse {
             log.warn("render_state_row_cells_get invalid data value={d}", .{@intFromEnum(data)});
             return .invalid_value;
         };
@@ -671,7 +671,7 @@ pub fn row_get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(RowData, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(RowData, @intFromEnum(data)) orelse {
             log.warn("render_state_row_get invalid data value={d}", .{@intFromEnum(data)});
             return .invalid_value;
         };
@@ -751,7 +751,7 @@ pub fn row_set(
     value: ?*const anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(RowOption, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(RowOption, @intFromEnum(option)) orelse {
             log.warn("render_state_row_set invalid option value={d}", .{@intFromEnum(option)});
             return .invalid_value;
         };
diff --git a/src/terminal/c/row.zig b/src/terminal/c/row.zig
index 66c398c8b..136d68359 100644
--- a/src/terminal/c/row.zig
+++ b/src/terminal/c/row.zig
@@ -68,7 +68,7 @@ pub fn get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(RowData, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(RowData, @intFromEnum(data)) orelse {
             return .invalid_value;
         };
     }
diff --git a/src/terminal/c/selection.zig b/src/terminal/c/selection.zig
index cb574ecc2..7f0af205f 100644
--- a/src/terminal/c/selection.zig
+++ b/src/terminal/c/selection.zig
@@ -253,7 +253,7 @@ fn selectionFormatter(
     opts: FormatOptions,
 ) error{ InvalidValue, NoValue }!formatterpkg.TerminalFormatter {
     if (opts.size < @sizeOf(FormatOptions)) return error.InvalidValue;
-    _ = std.meta.intToEnum(Format, @intFromEnum(opts.emit)) catch
+    _ = std.enums.fromInt(Format, @intFromEnum(opts.emit)) orelse
         return error.InvalidValue;
 
     const sel = if (opts.selection) |sel|
@@ -308,7 +308,7 @@ pub fn adjust(
     adjustment: Selection.Adjustment,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Selection.Adjustment, @intFromEnum(adjustment)) catch {
+        _ = std.enums.fromInt(Selection.Adjustment, @intFromEnum(adjustment)) orelse {
             log.warn("terminal_selection_adjust invalid adjustment value={d}", .{@intFromEnum(adjustment)});
             return .invalid_value;
         };
@@ -343,7 +343,7 @@ pub fn ordered(
     out_selection: ?*CSelection,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Selection.Order, @intFromEnum(desired)) catch {
+        _ = std.enums.fromInt(Selection.Order, @intFromEnum(desired)) orelse {
             log.warn("terminal_selection_ordered invalid desired value={d}", .{@intFromEnum(desired)});
             return .invalid_value;
         };
diff --git a/src/terminal/c/selection_gesture.zig b/src/terminal/c/selection_gesture.zig
index cc56da3c0..20d7386b6 100644
--- a/src/terminal/c/selection_gesture.zig
+++ b/src/terminal/c/selection_gesture.zig
@@ -241,7 +241,7 @@ pub fn event_new(
     event_type: EventType,
 ) callconv(lib.calling_conv) Result {
     const out = out_event orelse return .invalid_value;
-    _ = std.meta.intToEnum(EventType, @intFromEnum(event_type)) catch
+    _ = std.enums.fromInt(EventType, @intFromEnum(event_type)) orelse
         return .invalid_value;
 
     const alloc = lib.alloc.default(alloc_);
@@ -343,7 +343,7 @@ pub fn event_set(
     value: ?*const anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(EventOption, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(EventOption, @intFromEnum(option)) orelse {
             log.warn("selection_gesture_event_set invalid option value={d}", .{@intFromEnum(option)});
             return .invalid_value;
         };
@@ -365,7 +365,7 @@ pub fn get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Data, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(Data, @intFromEnum(data)) orelse {
             log.warn("selection_gesture_get invalid data value={d}", .{@intFromEnum(data)});
             return .invalid_value;
         };
@@ -738,24 +738,12 @@ fn clearWordBoundaryCodepoints(event: *EventWrapper, target: *[]const u21) void
     target.* = &selection_codepoints.default_word_boundaries;
 }
 
-fn instantFromNs(ns: u64) SelectionGesture.Time {
-    if (comptime builtin.target.cpu.arch == .wasm32 and
-        builtin.target.os.tag == .freestanding)
-    {
-        return ns;
-    }
-
-    return switch (builtin.os.tag) {
-        .windows, .uefi, .wasi => .{ .timestamp = ns },
-        else => .{ .timestamp = .{
-            .sec = @intCast(ns / std.time.ns_per_s),
-            .nsec = @intCast(ns % std.time.ns_per_s),
-        } },
-    };
+fn instantFromNs(ns: u64) std.Io.Timestamp {
+    return .fromNanoseconds(ns);
 }
 
 fn validBehavior(behavior: Behavior) bool {
-    _ = std.meta.intToEnum(Behavior, @intFromEnum(behavior)) catch return false;
+    _ = std.enums.fromInt(Behavior, @intFromEnum(behavior)) orelse return false;
     return true;
 }
 
diff --git a/src/terminal/c/sys.zig b/src/terminal/c/sys.zig
index c4b2b17f2..0cf0c6e3b 100644
--- a/src/terminal/c/sys.zig
+++ b/src/terminal/c/sys.zig
@@ -102,7 +102,7 @@ pub fn set(
     value: ?*const anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Option, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(Option, @intFromEnum(option)) orelse {
             return .invalid_value;
         };
     }
@@ -146,37 +146,30 @@ fn emitLog(level: LogLevel, scope: []const u8, message: []const u8) void {
 /// Emits logs in chunks. Almost all logs will be less than the chunk size
 /// but this allows emitting larger logs without heap allocation.
 const LogEmitter = struct {
+    const buffer_size = 2048;
+
     c_level: LogLevel,
     scope_text: []const u8,
-    buf: [2048]u8 = undefined,
-    pos: usize = 0,
+    writer: std.Io.Writer,
 
-    fn write(self: *@This(), bytes: []const u8) error{}!usize {
-        var remaining = bytes;
-        while (remaining.len > 0) {
-            const space = self.buf.len - self.pos;
-            if (space == 0) {
-                self.flush();
-                continue;
-            }
-
-            const n = @min(remaining.len, space);
-            @memcpy(self.buf[self.pos..][0..n], remaining[0..n]);
-            self.pos += n;
-            remaining = remaining[n..];
+    fn drain(w: *std.Io.Writer, data: []const []const u8, splat: usize) std.Io.Writer.Error!usize {
+        switch (data.len) {
+            0 => unreachable,
+            1 => if (splat == 0) return 0,
+            else => {},
         }
-
-        return bytes.len;
-    }
-
-    fn flush(self: *@This()) void {
-        if (self.pos == 0) return;
-        emitLog(
-            self.c_level,
-            self.scope_text,
-            self.buf[0..self.pos],
-        );
-        self.pos = 0;
+        const self: *@This() = @fieldParentPtr("writer", w);
+        if (w.end > 0) {
+            emitLog(
+                self.c_level,
+                self.scope_text,
+                w.buffer[0..w.end],
+            );
+        }
+        const len: usize = @min(data[0].len, w.buffer.len);
+        @memcpy(w.buffer[0..len], data[0][0..len]);
+        w.end = len;
+        return len;
     }
 };
 
@@ -197,18 +190,20 @@ pub fn logFn(
     const scope_text: []const u8 = if (scope == .default) "" else @tagName(scope);
     const c_level = LogLevel.fromStd(level);
 
-    var ctx: LogEmitter = .{
+    var log_emitter_buffer: [LogEmitter.buffer_size]u8 = undefined;
+    var log_emitter: LogEmitter = .{
         .c_level = c_level,
         .scope_text = scope_text,
+        .writer = .{
+            .buffer = &log_emitter_buffer,
+            .vtable = &.{
+                .drain = LogEmitter.drain,
+            },
+        },
     };
-    const writer: std.io.GenericWriter(
-        *LogEmitter,
-        error{},
-        LogEmitter.write,
-    ) = .{ .context = &ctx };
 
-    nosuspend writer.print(format, args) catch {};
-    ctx.flush();
+    nosuspend log_emitter.writer.print(format, args) catch {};
+    log_emitter.writer.flush() catch {};
 }
 
 /// Built-in log callback that writes to stderr.
@@ -239,13 +234,13 @@ pub fn logStderr(
     };
 
     var buffer: [64]u8 = undefined;
-    const writer = std.debug.lockStderrWriter(&buffer);
-    defer std.debug.unlockStderrWriter();
+    var locked_stderr = std.debug.lockStderr(&buffer);
+    defer std.debug.unlockStderr();
     nosuspend {
         if (scope.len > 0) {
-            writer.print("[{s}]({s}): {s}\n", .{ level_text, scope, message }) catch {};
+            locked_stderr.file_writer.interface.print("[{s}]({s}): {s}\n", .{ level_text, scope, message }) catch {};
         } else {
-            writer.print("[{s}]: {s}\n", .{ level_text, message }) catch {};
+            locked_stderr.file_writer.interface.print("[{s}]: {s}\n", .{ level_text, message }) catch {};
         }
     }
 }
diff --git a/src/terminal/c/terminal.zig b/src/terminal/c/terminal.zig
index cafef912f..56cdce5e1 100644
--- a/src/terminal/c/terminal.zig
+++ b/src/terminal/c/terminal.zig
@@ -1,3 +1,4 @@
+const builtin = @import("builtin");
 const std = @import("std");
 const testing = std.testing;
 const build_options = @import("terminal_options");
@@ -26,19 +27,40 @@ const style_c = @import("style.zig");
 const color = @import("../color.zig");
 const clipboard = @import("../clipboard.zig");
 const Result = @import("result.zig").Result;
+const assert = @import("../../quirks.zig").inlineAssert;
 
 const Handler = @import("../stream_terminal.zig").Handler;
 
+const max_path_bytes = if (builtin.os.tag == .freestanding) 4096 else std.fs.max_path_bytes;
+
 const log = std.log.scoped(.terminal_c);
 
 /// Wrapper around ZigTerminal that tracks additional state for C API usage,
 /// such as the persistent VT stream needed to handle escape sequences split
 /// across multiple vt_write calls.
 const TerminalWrapper = struct {
+    const IoImpl = if (builtin.os.tag != .freestanding) *std.Io.Threaded else void;
+
     terminal: *ZigTerminal,
+    /// We need to keep an I/O instance here as part of the terminal since we
+    /// have no way of taking it in the C API. This is set up in `new` and
+    /// destroyed on `free`.
+    ///
+    /// This is set to null on freestanding platforms, which get std.Io.failing
+    /// instead.
+    io_impl: IoImpl,
+    /// We also need to store a temp dir path for some operations (e.g., kitty
+    /// graphics). This provides stable storage for the API calls.
+    tmp_dir_path: [max_path_bytes]u8,
     stream: Stream,
     effects: Effects = .{},
     tracked_grid_refs: std.AutoArrayHashMapUnmanaged(*grid_ref_tracked_c.TrackedGridRef, void) = .{},
+
+    /// Fetches a `TerminalWrapper` reference from a `Handler`.
+    fn fromHandler(handler: *Handler) *TerminalWrapper {
+        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
+        return @alignCast(@fieldParentPtr("stream", stream_ptr));
+    }
 };
 
 /// A single MIME representation in a clipboard write.
@@ -149,22 +171,19 @@ const Effects = struct {
     };
 
     fn writePtyTrampoline(handler: *Handler, data: [:0]const u8) void {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.write_pty orelse return;
         func(@ptrCast(wrapper), wrapper.effects.userdata, data.ptr, data.len);
     }
 
     fn bellTrampoline(handler: *Handler) void {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.bell orelse return;
         func(@ptrCast(wrapper), wrapper.effects.userdata);
     }
 
     fn clipboardWriteTrampoline(handler: *Handler, write: clipboard.Write) clipboard.WriteResult {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.clipboard_write orelse return .unsupported;
 
         // Most protocols currently produce one representation, so keep that
@@ -201,8 +220,7 @@ const Effects = struct {
     }
 
     fn colorSchemeTrampoline(handler: *Handler) ?device_status.ColorScheme {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.color_scheme orelse return null;
         var scheme: device_status.ColorScheme = undefined;
         if (func(@ptrCast(wrapper), wrapper.effects.userdata, &scheme)) return scheme;
@@ -210,8 +228,7 @@ const Effects = struct {
     }
 
     fn deviceAttributesTrampoline(handler: *Handler) device_attributes.Attributes {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.device_attributes_cb orelse return .{};
 
         // Get our attributes from the callback.
@@ -241,8 +258,7 @@ const Effects = struct {
     }
 
     fn enquiryTrampoline(handler: *Handler) []const u8 {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.enquiry orelse return "";
         const result = func(@ptrCast(wrapper), wrapper.effects.userdata);
         if (result.len == 0) return "";
@@ -250,8 +266,7 @@ const Effects = struct {
     }
 
     fn xtversionTrampoline(handler: *Handler) []const u8 {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.xtversion orelse return "";
         const result = func(@ptrCast(wrapper), wrapper.effects.userdata);
         if (result.len == 0) return "";
@@ -259,22 +274,19 @@ const Effects = struct {
     }
 
     fn titleChangedTrampoline(handler: *Handler) void {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.title_changed orelse return;
         func(@ptrCast(wrapper), wrapper.effects.userdata);
     }
 
     fn pwdChangedTrampoline(handler: *Handler) void {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.pwd_changed orelse return;
         func(@ptrCast(wrapper), wrapper.effects.userdata);
     }
 
     fn sizeTrampoline(handler: *Handler) ?size_report.Size {
-        const stream_ptr: *Stream = @fieldParentPtr("handler", handler);
-        const wrapper: *TerminalWrapper = @fieldParentPtr("stream", stream_ptr);
+        const wrapper = TerminalWrapper.fromHandler(handler);
         const func = wrapper.effects.size_cb orelse return null;
         var s: size_report.Size = undefined;
         if (func(@ptrCast(wrapper), wrapper.effects.userdata, &s)) return s;
@@ -338,12 +350,24 @@ fn new_(
         return error.OutOfMemory;
     errdefer alloc.destroy(wrapper);
 
+    const has_nonfailing_io = builtin.os.tag != .freestanding;
+    const io_impl: TerminalWrapper.IoImpl = if (has_nonfailing_io) io_impl: {
+        const ptr = try alloc.create(std.Io.Threaded);
+        ptr.* = .init_single_threaded;
+        break :io_impl ptr;
+    } else {};
+    errdefer if (has_nonfailing_io) alloc.destroy(io_impl);
+
     // Setup our terminal
-    t.* = try .init(alloc, .{
-        .cols = opts.cols,
-        .rows = opts.rows,
-        .max_scrollback = opts.max_scrollback,
-    });
+    t.* = try .init(
+        if (has_nonfailing_io) io_impl.io() else std.Io.failing,
+        alloc,
+        .{
+            .cols = opts.cols,
+            .rows = opts.rows,
+            .max_scrollback = opts.max_scrollback,
+        },
+    );
     errdefer t.deinit(alloc);
 
     // libghostty-vt embedders don't necessarily install Ghostty's shell
@@ -369,6 +393,8 @@ fn new_(
 
     wrapper.* = .{
         .terminal = t,
+        .io_impl = io_impl,
+        .tmp_dir_path = undefined, // Only used if temporary directory is set with API calls
         .stream = .initAlloc(alloc, handler),
     };
 
@@ -401,9 +427,7 @@ pub fn compress(
 ) callconv(lib.calling_conv) Result {
     const t: *ZigTerminal = (terminal_ orelse return .invalid_value).terminal;
     const out_result = out_result_ orelse return .invalid_value;
-    const mode = std.meta.intToEnum(CompressionMode, mode_) catch
-        return .invalid_value;
-
+    const mode = std.enums.fromInt(CompressionMode, mode_) orelse return .invalid_value;
     out_result.* = t.compress(mode);
     return .success;
 }
@@ -457,10 +481,10 @@ pub const Option = enum(c_int) {
             .color_palette => ?*const color.PaletteC,
             .kitty_image_storage_limit => ?*const u64,
             .kitty_image_medium_file,
-            .kitty_image_medium_temp_file,
             .kitty_image_medium_shared_mem,
             .glyph_protocol,
             => ?*const bool,
+            .kitty_image_medium_temp_file => ?*const lib.String,
             .apc_max_bytes, .apc_max_bytes_kitty => ?*const usize,
             .selection => ?*const selection_c.CSelection,
             .default_cursor_style => ?*const TerminalCursorStyle,
@@ -475,7 +499,7 @@ pub fn set(
     value: ?*const anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(Option, @intFromEnum(option)) catch {
+        _ = std.enums.fromInt(Option, @intFromEnum(option)) orelse {
             log.warn("terminal_set invalid option value={d}", .{@intFromEnum(option)});
             return .invalid_value;
         };
@@ -541,11 +565,10 @@ fn setTyped(
             var it = wrapper.terminal.screens.all.iterator();
             while (it.next()) |entry| {
                 const screen = entry.value.*;
-                screen.kitty_images.setLimit(screen.alloc, screen, limit) catch return .out_of_memory;
+                screen.kitty_images.setLimit(screen.io, screen.alloc, screen, limit) catch return .out_of_memory;
             }
         },
         .kitty_image_medium_file,
-        .kitty_image_medium_temp_file,
         .kitty_image_medium_shared_mem,
         => {
             if (comptime !build_options.kitty_graphics) return .success;
@@ -555,12 +578,31 @@ fn setTyped(
                 const screen = entry.value.*;
                 switch (option) {
                     .kitty_image_medium_file => screen.kitty_images.image_limits.file = val,
-                    .kitty_image_medium_temp_file => screen.kitty_images.image_limits.temporary_file = val,
                     .kitty_image_medium_shared_mem => screen.kitty_images.image_limits.shared_memory = val,
                     else => unreachable,
                 }
             }
         },
+        .kitty_image_medium_temp_file => {
+            if (comptime !build_options.kitty_graphics) return .success;
+            if (value) |v| {
+                if (v.len > wrapper.tmp_dir_path.len) return .out_of_memory;
+                @memcpy(&wrapper.tmp_dir_path, v.ptr[0..v.len]);
+                var it = wrapper.terminal.screens.all.iterator();
+                while (it.next()) |entry| {
+                    const screen = entry.value.*;
+                    screen.kitty_images.image_limits.temporary_file = .{
+                        .enabled = .{ .directory = wrapper.tmp_dir_path[0..v.len] },
+                    };
+                }
+            } else {
+                var it = wrapper.terminal.screens.all.iterator();
+                while (it.next()) |entry| {
+                    const screen = entry.value.*;
+                    screen.kitty_images.image_limits.temporary_file = .disabled;
+                }
+            }
+        },
         .apc_max_bytes => {
             wrapper.stream.handler.apc_handler.max_bytes = if (value) |ptr|
                 .initFull(ptr.*)
@@ -763,9 +805,9 @@ pub const TerminalData = enum(c_int) {
             .color_palette, .color_palette_default => color.PaletteC,
             .kitty_image_storage_limit => u64,
             .kitty_image_medium_file,
-            .kitty_image_medium_temp_file,
             .kitty_image_medium_shared_mem,
             => bool,
+            .kitty_image_medium_temp_file => lib.String,
             .kitty_graphics => KittyGraphics,
             .selection => selection_c.CSelection,
         };
@@ -778,7 +820,7 @@ pub fn get(
     out: ?*anyopaque,
 ) callconv(lib.calling_conv) Result {
     if (comptime std.debug.runtime_safety) {
-        _ = std.meta.intToEnum(TerminalData, @intFromEnum(data)) catch {
+        _ = std.enums.fromInt(TerminalData, @intFromEnum(data)) orelse {
             log.warn("terminal_get invalid data value={d}", .{@intFromEnum(data)});
             return .invalid_value;
         };
@@ -868,7 +910,11 @@ fn getTyped(
         },
         .kitty_image_medium_temp_file => {
             if (comptime !build_options.kitty_graphics) return .no_value;
-            out.* = t.screens.active.kitty_images.image_limits.temporary_file;
+            const dir = switch (t.screens.active.kitty_images.image_limits.temporary_file) {
+                .enabled => |d| d.directory,
+                .disabled => "",
+            };
+            out.* = .{ .ptr = dir.ptr, .len = dir.len };
         },
         .kitty_image_medium_shared_mem => {
             if (comptime !build_options.kitty_graphics) return .no_value;
@@ -967,6 +1013,11 @@ pub fn free(terminal_: Terminal) callconv(lib.calling_conv) void {
     wrapper.tracked_grid_refs.deinit(alloc);
     wrapper.stream.deinit();
     t.deinit(alloc);
+    if (builtin.os.tag != .freestanding) {
+        // Deinit is always safe to call, even for single-threaded instances
+        wrapper.io_impl.deinit();
+        alloc.destroy(wrapper.io_impl);
+    }
     alloc.destroy(t);
     alloc.destroy(wrapper);
 }
diff --git a/src/terminal/color.zig b/src/terminal/color.zig
index 92de35781..1909ba2a0 100644
--- a/src/terminal/color.zig
+++ b/src/terminal/color.zig
@@ -463,10 +463,7 @@ pub const Dynamic = enum(u5) {
     /// "Each successive parameter changes the next color in the list.  The
     /// value of Ps tells the starting point in the list."
     pub fn next(self: Dynamic) ?Dynamic {
-        return std.meta.intToEnum(
-            Dynamic,
-            @intFromEnum(self) + 1,
-        ) catch null;
+        return std.enums.fromInt(Dynamic, @intFromEnum(self) + 1);
     }
 
     test "next" {
diff --git a/src/terminal/compress/lz4_differential.zig b/src/terminal/compress/lz4_differential.zig
index bbf3b2765..f164ec048 100644
--- a/src/terminal/compress/lz4_differential.zig
+++ b/src/terminal/compress/lz4_differential.zig
@@ -485,7 +485,7 @@ test "lz4 differential light" {
 test "lz4 differential exhaustive" {
     // Slow. Enable explicitly, ideally together with a test filter:
     //   GHOSTTY_LZ4_SLOW=1 zig build test -Dtest-filter="lz4 differential"
-    if (!std.process.hasEnvVarConstant("GHOSTTY_LZ4_SLOW"))
+    if (!std.testing.environ.containsConstant("GHOSTTY_LZ4_SLOW"))
         return error.SkipZigTest;
 
     // Several independent seeds; the suite is deterministic per seed.
diff --git a/src/terminal/device_status.zig b/src/terminal/device_status.zig
index fd1a9b7e6..f61ee4a39 100644
--- a/src/terminal/device_status.zig
+++ b/src/terminal/device_status.zig
@@ -35,24 +35,18 @@ pub fn encodeColorSchemeReport(
 
 /// An enum(u16) of the available device status requests.
 pub const Request = dsr_enum: {
-    const EnumField = std.builtin.Type.EnumField;
-    var fields: [entries.len]EnumField = undefined;
-    for (entries, 0..) |entry, i| {
-        fields[i] = .{
-            .name = entry.name,
-            .value = @as(Tag.Backing, @bitCast(Tag{
-                .value = entry.value,
-                .question = entry.question,
-            })),
-        };
+    var names: [entries.len][]const u8 = undefined;
+    var values: [entries.len]Tag.Backing = undefined;
+
+    for (entries, &names, &values) |entry, *name, *value| {
+        name.* = entry.name;
+        value.* = @bitCast(Tag{
+            .value = entry.value,
+            .question = entry.question,
+        });
     }
 
-    break :dsr_enum @Type(.{ .@"enum" = .{
-        .tag_type = Tag.Backing,
-        .fields = &fields,
-        .decls = &.{},
-        .is_exhaustive = true,
-    } });
+    break :dsr_enum @Enum(Tag.Backing, .exhaustive, &names, &values);
 };
 
 /// The tag type for our enum is a u16 but we use a packed struct
diff --git a/src/terminal/formatter.zig b/src/terminal/formatter.zig
index 553ea28d0..f8cf61e64 100644
--- a/src/terminal/formatter.zig
+++ b/src/terminal/formatter.zig
@@ -941,8 +941,7 @@ pub const PageFormatter = struct {
                 // Setup our div. We use a buffer here that should always
                 // fit the stuff we need, in order to make counting bytes easier.
                 var buf: [1024]u8 = undefined;
-                var stream = std.io.fixedBufferStream(&buf);
-                const buf_writer = stream.writer();
+                var buf_writer: std.Io.Writer = .fixed(&buf);
 
                 // Monospace and whitespace preserving
                 buf_writer.writeAll("<div style=\"font-family: monospace; white-space: pre;") catch return error.WriteFailed;
@@ -959,7 +958,7 @@ pub const PageFormatter = struct {
 
                 buf_writer.writeAll("\">") catch return error.WriteFailed;
 
-                const header = stream.getWritten();
+                const header = buf_writer.buffered();
                 try writer.writeAll(header);
                 if (self.point_map) |*map| map.map.appendNTimes(
                     map.alloc,
@@ -971,8 +970,7 @@ pub const PageFormatter = struct {
             .vt => {
                 // OSC 10 sets foreground color, OSC 11 sets background color
                 var buf: [512]u8 = undefined;
-                var stream = std.io.fixedBufferStream(&buf);
-                const buf_writer = stream.writer();
+                var buf_writer: std.Io.Writer = .fixed(&buf);
                 if (self.opts.foreground) |fg| {
                     buf_writer.print(
                         "\x1b]10;rgb:{x:0>2}/{x:0>2}/{x:0>2}\x1b\\",
@@ -986,7 +984,7 @@ pub const PageFormatter = struct {
                     ) catch return error.WriteFailed;
                 }
 
-                const header = stream.getWritten();
+                const header = buf_writer.buffered();
                 try writer.writeAll(header);
                 if (self.point_map) |*map| map.map.appendNTimes(
                     map.alloc,
@@ -1375,7 +1373,7 @@ pub const PageFormatter = struct {
             return;
         }
 
-        try self.writeCodepointWithReplacement(writer, cell.content.codepoint);
+        try self.writeCodepointWithReplacement(writer, cell.content.codepoint.data);
         if (comptime tag == .codepoint_grapheme) {
             for (self.page.lookupGrapheme(cell).?) |cp| {
                 try self.writeCodepointWithReplacement(writer, cp);
@@ -1475,7 +1473,7 @@ pub const PageFormatter = struct {
 
             .bg_color_palette => .{
                 .bg_color = .{
-                    .palette = cell.content.color_palette,
+                    .palette = cell.content.color_palette.data,
                 },
             },
 
@@ -1591,11 +1589,12 @@ pub const PageFormatter = struct {
 test "Page plain single line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -1638,11 +1637,12 @@ test "Page plain single line" {
 test "Page plain single line soft-wrapped unwrapped" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 3,
         .rows = 5,
     });
@@ -1708,11 +1708,12 @@ test "Page plain single line soft-wrapped unwrapped" {
 test "Page plain single wide char" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -1799,11 +1800,12 @@ test "Page plain single wide char" {
 test "Page plain single wide char soft-wrapped unwrapped" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 3,
         .rows = 24,
     });
@@ -1916,11 +1918,12 @@ test "Page plain single wide char soft-wrapped unwrapped" {
 test "Page plain multiline" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -1967,11 +1970,12 @@ test "Page plain multiline" {
 test "Page plain multiline rectangle" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2021,11 +2025,12 @@ test "Page plain multiline rectangle" {
 test "Page plain multi blank lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2074,11 +2079,12 @@ test "Page plain multi blank lines" {
 test "Page plain trailing blank lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2127,11 +2133,12 @@ test "Page plain trailing blank lines" {
 test "Page plain trailing whitespace" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2180,11 +2187,12 @@ test "Page plain trailing whitespace" {
 test "Page plain trailing whitespace no trim" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2236,11 +2244,12 @@ test "Page plain trailing whitespace no trim" {
 test "Page plain with prior trailing state rows" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2282,11 +2291,12 @@ test "Page plain with prior trailing state rows" {
 test "Page plain with prior trailing state cells no wrapped line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2327,11 +2337,12 @@ test "Page plain with prior trailing state cells no wrapped line" {
 test "Page plain with prior trailing state cells with wrap continuation" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2381,11 +2392,12 @@ test "Page plain with prior trailing state cells with wrap continuation" {
 test "Page plain soft-wrapped without unwrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 24,
     });
@@ -2430,11 +2442,12 @@ test "Page plain soft-wrapped without unwrap" {
 test "Page plain soft-wrapped with unwrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 24,
     });
@@ -2478,11 +2491,12 @@ test "Page plain soft-wrapped with unwrap" {
 test "Page plain soft-wrapped 3 lines without unwrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 24,
     });
@@ -2532,11 +2546,12 @@ test "Page plain soft-wrapped 3 lines without unwrap" {
 test "Page plain soft-wrapped 3 lines with unwrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 24,
     });
@@ -2584,11 +2599,12 @@ test "Page plain soft-wrapped 3 lines with unwrap" {
 test "Page plain start_y subset" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2631,11 +2647,12 @@ test "Page plain start_y subset" {
 test "Page plain end_y subset" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2678,11 +2695,12 @@ test "Page plain end_y subset" {
 test "Page plain start_y and end_y range" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2726,11 +2744,12 @@ test "Page plain start_y and end_y range" {
 test "Page plain start_y out of bounds" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2764,11 +2783,12 @@ test "Page plain start_y out of bounds" {
 test "Page plain end_y greater than rows" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2807,11 +2827,12 @@ test "Page plain end_y greater than rows" {
 test "Page plain end_y less than start_y" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2846,11 +2867,12 @@ test "Page plain end_y less than start_y" {
 test "Page plain start_x on first row only" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2888,11 +2910,12 @@ test "Page plain start_x on first row only" {
 test "Page plain end_x on last row only" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2941,11 +2964,12 @@ test "Page plain end_x on last row only" {
 test "Page plain start_x and end_x multiline" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -2998,11 +3022,12 @@ test "Page plain start_x and end_x multiline" {
 test "Page plain start_x out of bounds" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3036,11 +3061,12 @@ test "Page plain start_x out of bounds" {
 test "Page plain end_x greater than cols" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3078,11 +3104,12 @@ test "Page plain end_x greater than cols" {
 test "Page plain end_x less than start_x single row" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3118,11 +3145,12 @@ test "Page plain end_x less than start_x single row" {
 test "Page plain start_y non-zero ignores trailing state" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3162,11 +3190,12 @@ test "Page plain start_y non-zero ignores trailing state" {
 test "Page plain start_x non-zero ignores trailing state" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3206,11 +3235,12 @@ test "Page plain start_x non-zero ignores trailing state" {
 test "Page plain start_y and start_x zero uses trailing state" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3253,11 +3283,12 @@ test "Page plain start_y and start_x zero uses trailing state" {
 test "Page plain single line with styling" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3299,11 +3330,12 @@ test "Page plain single line with styling" {
 test "Page VT single line plain text" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3338,11 +3370,12 @@ test "Page VT single line plain text" {
 test "Page VT single line with bold" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3384,11 +3417,12 @@ test "Page VT single line with bold" {
 test "Page VT multiple styles" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3419,11 +3453,12 @@ test "Page VT multiple styles" {
 test "Page VT with foreground color" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3465,11 +3500,12 @@ test "Page VT with foreground color" {
 test "Page VT with background and foreground colors" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3502,11 +3538,12 @@ test "Page VT with background and foreground colors" {
 test "Page VT multi-line with styles" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3539,11 +3576,12 @@ test "Page VT multi-line with styles" {
 test "Page VT duplicate style not emitted twice" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3574,11 +3612,12 @@ test "Page VT duplicate style not emitted twice" {
 test "PageList plain single line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3610,11 +3649,12 @@ test "PageList plain single line" {
 test "PageList plain spanning two pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3683,11 +3723,12 @@ test "PageList plain spanning two pages" {
 test "PageList soft-wrapped line spanning two pages without unwrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -3747,11 +3788,12 @@ test "PageList soft-wrapped line spanning two pages without unwrap" {
 test "PageList soft-wrapped line spanning two pages with unwrap" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -3808,11 +3850,12 @@ test "PageList soft-wrapped line spanning two pages with unwrap" {
 test "PageList VT spanning two pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3868,11 +3911,12 @@ test "PageList VT spanning two pages" {
 test "PageList plain with x offset on single page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3914,11 +3958,12 @@ test "PageList plain with x offset on single page" {
 test "PageList plain with x offset spanning two pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -3984,11 +4029,12 @@ test "PageList plain with x offset spanning two pages" {
 test "PageList plain with start_x only" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4025,11 +4071,12 @@ test "PageList plain with start_x only" {
 test "PageList plain with end_x only" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4078,11 +4125,12 @@ test "PageList plain with end_x only" {
 test "PageList plain rectangle basic" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 30,
         .rows = 5,
     });
@@ -4118,11 +4166,12 @@ test "PageList plain rectangle basic" {
 test "PageList plain rectangle with EOL" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 30,
         .rows = 5,
     });
@@ -4160,11 +4209,12 @@ test "PageList plain rectangle with EOL" {
 test "PageList plain rectangle more complex with breaks" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 30,
         .rows = 8,
     });
@@ -4206,11 +4256,12 @@ test "PageList plain rectangle more complex with breaks" {
 test "TerminalFormatter plain no selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4230,11 +4281,12 @@ test "TerminalFormatter plain no selection" {
 test "TerminalFormatter vt with palette" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4255,7 +4307,7 @@ test "TerminalFormatter vt with palette" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4275,11 +4327,12 @@ test "TerminalFormatter vt with palette" {
 test "TerminalFormatter with selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4304,11 +4357,12 @@ test "TerminalFormatter with selection" {
 test "TerminalFormatter plain with pin_map" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4341,11 +4395,12 @@ test "TerminalFormatter plain with pin_map" {
 test "TerminalFormatter plain multiline with pin_map" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4389,11 +4444,12 @@ test "TerminalFormatter plain multiline with pin_map" {
 test "TerminalFormatter vt with palette and pin_map" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4426,11 +4482,12 @@ test "TerminalFormatter vt with palette and pin_map" {
 test "TerminalFormatter with selection and pin_map" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4470,11 +4527,12 @@ test "TerminalFormatter with selection and pin_map" {
 test "Screen plain single line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4507,11 +4565,12 @@ test "Screen plain single line" {
 test "Screen plain multiline" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4555,11 +4614,12 @@ test "Screen plain multiline" {
 test "Screen plain with selection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4599,11 +4659,12 @@ test "Screen plain with selection" {
 test "Screen vt with cursor position" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4626,7 +4687,7 @@ test "Screen vt with cursor position" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4658,11 +4719,12 @@ test "Screen vt with cursor position" {
 test "Screen vt with style" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4685,7 +4747,7 @@ test "Screen vt with style" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4710,11 +4772,12 @@ test "Screen vt with style" {
 test "Screen vt with hyperlink" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4737,7 +4800,7 @@ test "Screen vt with hyperlink" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4770,11 +4833,12 @@ test "Screen vt with hyperlink" {
 test "Screen vt with protection" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4797,7 +4861,7 @@ test "Screen vt with protection" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4822,11 +4886,12 @@ test "Screen vt with protection" {
 test "Screen vt with kitty keyboard" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4849,7 +4914,7 @@ test "Screen vt with kitty keyboard" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4876,11 +4941,12 @@ test "Screen vt with kitty keyboard" {
 test "Screen vt with charsets" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4903,7 +4969,7 @@ test "Screen vt with charsets" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4933,11 +4999,12 @@ test "Screen vt with charsets" {
 test "Terminal vt with scrolling region" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4956,7 +5023,7 @@ test "Terminal vt with scrolling region" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -4977,11 +5044,12 @@ test "Terminal vt with scrolling region" {
 test "Terminal vt with modes" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5003,7 +5071,7 @@ test "Terminal vt with modes" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5023,11 +5091,12 @@ test "Terminal vt with modes" {
 test "Terminal vt with tabstops" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5050,7 +5119,7 @@ test "Terminal vt with tabstops" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5074,11 +5143,12 @@ test "Terminal vt with tabstops" {
 test "Terminal vt with keyboard modes" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5098,7 +5168,7 @@ test "Terminal vt with keyboard modes" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5117,11 +5187,12 @@ test "Terminal vt with keyboard modes" {
 test "Terminal vt with pwd" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5140,7 +5211,7 @@ test "Terminal vt with pwd" {
     const output = builder.writer.buffered();
 
     // Create a second terminal and apply the output
-    var t2 = try Terminal.init(alloc, .{
+    var t2 = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5158,11 +5229,12 @@ test "Terminal vt with pwd" {
 test "Page html with multiple styles" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5194,11 +5266,12 @@ test "Page html with multiple styles" {
 test "Page html plain text" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5226,11 +5299,12 @@ test "Page html plain text" {
 test "Page html with colors" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5260,11 +5334,12 @@ test "Page html with colors" {
 test "TerminalFormatter html with palette" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5297,11 +5372,12 @@ test "TerminalFormatter html with palette" {
 test "Page html with background and foreground colors" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5332,11 +5408,12 @@ test "Page html with background and foreground colors" {
 test "Page html with escaping" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5402,11 +5479,12 @@ test "Page html with escaping" {
 test "Page html with unicode as numeric entities" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5436,11 +5514,12 @@ test "Page html with unicode as numeric entities" {
 test "Page html ascii characters unchanged" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5468,11 +5547,12 @@ test "Page html ascii characters unchanged" {
 test "Page html mixed ascii and unicode" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5500,11 +5580,12 @@ test "Page html mixed ascii and unicode" {
 test "Page VT with palette option emits RGB" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5544,11 +5625,12 @@ test "Page VT with palette option emits RGB" {
 test "Page html with palette option emits RGB" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5598,11 +5680,12 @@ test "Page html with palette option emits RGB" {
 test "Page VT style reset properly closes styles" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5629,11 +5712,12 @@ test "Page VT style reset properly closes styles" {
 test "Page codepoint_map single replacement" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5688,11 +5772,12 @@ test "Page codepoint_map single replacement" {
 test "Page codepoint_map conflicting replacement prefers last" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5730,11 +5815,12 @@ test "Page codepoint_map conflicting replacement prefers last" {
 test "Page codepoint_map replace with string" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5786,11 +5872,12 @@ test "Page codepoint_map replace with string" {
 test "Page codepoint_map range replacement" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5824,11 +5911,12 @@ test "Page codepoint_map range replacement" {
 test "Page codepoint_map multiple ranges" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5868,11 +5956,12 @@ test "Page codepoint_map multiple ranges" {
 test "Page codepoint_map unicode replacement" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -5933,11 +6022,12 @@ test "Page codepoint_map unicode replacement" {
 test "Page codepoint_map with styled formats" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 24,
     });
@@ -5974,11 +6064,12 @@ test "Page codepoint_map with styled formats" {
 test "Page codepoint_map empty map" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -6011,11 +6102,12 @@ test "Page VT background color on trailing blank cells" {
     // This causes TUIs like htop to lose background colors on rehydration.
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 20,
         .rows = 5,
     });
@@ -6062,11 +6154,12 @@ test "Page VT background color on trailing blank cells" {
 test "Page HTML with hyperlinks" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -6096,11 +6189,12 @@ test "Page HTML with hyperlinks" {
 test "Page HTML with multiple hyperlinks" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -6133,11 +6227,12 @@ test "Page HTML with multiple hyperlinks" {
 test "Page HTML with hyperlink escaping" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -6167,11 +6262,12 @@ test "Page HTML with hyperlink escaping" {
 test "Page HTML with styled hyperlink" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -6202,11 +6298,12 @@ test "Page HTML with styled hyperlink" {
 test "Page HTML hyperlink closes style before anchor" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -6237,11 +6334,12 @@ test "Page HTML hyperlink closes style before anchor" {
 test "Page HTML hyperlink point map maps closing to previous cell" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var builder: std.Io.Writer.Allocating = .init(alloc);
     defer builder.deinit();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
diff --git a/src/terminal/hash_map.zig b/src/terminal/hash_map.zig
index d8feddcd1..abef87e3b 100644
--- a/src/terminal/hash_map.zig
+++ b/src/terminal/hash_map.zig
@@ -70,8 +70,24 @@ fn AutoHashMapUnmanaged(
 
 fn AutoContext(comptime K: type) type {
     return struct {
-        pub const hash = std.hash_map.getAutoHashFn(K, @This());
         pub const eql = std.hash_map.getAutoEqlFn(K, @This());
+
+        pub fn hash(_: @This(), key: K) u64 {
+            if (comptime std.meta.hasUniqueRepresentation(K)) {
+                // LLVM 21 (Zig 0.16) failed to inline this which resulted
+                // in a measurable almost 2x slowdown on our hyperlink map
+                // benchmark. So, force it.
+                return @call(
+                    .always_inline,
+                    std.hash.Wyhash.hash,
+                    .{ 0, std.mem.asBytes(&key) },
+                );
+            }
+
+            var hasher = std.hash.Wyhash.init(0);
+            std.hash.autoHash(&hasher, key);
+            return hasher.final();
+        }
     };
 }
 
diff --git a/src/terminal/kitty/graphics_exec.zig b/src/terminal/kitty/graphics_exec.zig
index 6c72ec4e9..e0756ccc7 100644
--- a/src/terminal/kitty/graphics_exec.zig
+++ b/src/terminal/kitty/graphics_exec.zig
@@ -21,6 +21,7 @@ const log = std.log.scoped(.kitty_gfx);
 /// The allocator must be the same allocator that was used to build
 /// the command.
 pub fn execute(
+    io: std.Io,
     alloc: Allocator,
     terminal: *Terminal,
     cmd: *const Command,
@@ -44,9 +45,9 @@ pub fn execute(
     var quiet = cmd.quiet;
 
     const resp_: ?Response = switch (cmd.control) {
-        .query => query(alloc, terminal, cmd),
-        .display => display(alloc, terminal, cmd),
-        .delete => delete(alloc, terminal, cmd),
+        .query => query(io, alloc, terminal, cmd),
+        .display => display(io, alloc, terminal, cmd),
+        .delete => delete(io, alloc, terminal, cmd),
 
         .transmit, .transmit_and_display => resp: {
             // If we're transmitting, then our `q` setting value is complicated.
@@ -65,7 +66,7 @@ pub fn execute(
                 },
             };
 
-            break :resp transmit(alloc, terminal, cmd);
+            break :resp transmit(io, alloc, terminal, cmd);
         },
 
         .transmit_animation_frame,
@@ -95,6 +96,7 @@ pub fn execute(
 /// success/error but does not persist any of the command to the terminal
 /// state.
 fn query(
+    io: std.Io,
     alloc: Allocator,
     terminal: *const Terminal,
     cmd: *const Command,
@@ -117,7 +119,7 @@ fn query(
 
     // Attempt to load the image. If we cannot, then set an appropriate error.
     const storage = &terminal.screens.active.kitty_images;
-    var loading = LoadingImage.init(alloc, cmd, storage.image_limits) catch |err| {
+    var loading = LoadingImage.init(io, alloc, cmd, storage.image_limits) catch |err| {
         encodeError(&result, err);
         return result;
     };
@@ -131,6 +133,7 @@ fn query(
 /// This loads the image, validates it, and puts it into the terminal
 /// screen storage. It does not display the image.
 fn transmit(
+    io: std.Io,
     alloc: Allocator,
     terminal: *Terminal,
     cmd: *const Command,
@@ -145,7 +148,7 @@ fn transmit(
         return .{ .message = "EINVAL: image ID and number are mutually exclusive" };
     }
 
-    const load = loadAndAddImage(alloc, terminal, cmd) catch |err| {
+    const load = loadAndAddImage(io, alloc, terminal, cmd) catch |err| {
         encodeError(&result, err);
         return result;
     };
@@ -158,7 +161,7 @@ fn transmit(
         assert(!load.more);
         var d_copy = d;
         d_copy.image_id = load.image.id;
-        result = display(alloc, terminal, &.{
+        result = display(io, alloc, terminal, &.{
             .control = .{ .display = d_copy },
             .quiet = cmd.quiet,
         });
@@ -180,6 +183,7 @@ fn transmit(
 
 /// Display a previously transmitted image.
 fn display(
+    io: std.Io,
     alloc: Allocator,
     terminal: *Terminal,
     cmd: *const Command,
@@ -250,6 +254,7 @@ fn display(
         .z = d.z,
     };
     storage.addPlacement(
+        io,
         alloc,
         img.id,
         result.placement_id,
@@ -286,18 +291,20 @@ fn display(
 
 /// Display a previously transmitted image.
 fn delete(
+    io: std.Io,
     alloc: Allocator,
     terminal: *Terminal,
     cmd: *const Command,
 ) Response {
     const storage = &terminal.screens.active.kitty_images;
-    storage.delete(alloc, terminal, cmd.control.delete);
+    storage.delete(io, alloc, terminal, cmd.control.delete);
 
     // Delete never responds on success
     return .{};
 }
 
 fn loadAndAddImage(
+    io: std.Io,
     alloc: Allocator,
     terminal: *Terminal,
     cmd: *const Command,
@@ -327,7 +334,7 @@ fn loadAndAddImage(
         }
 
         break :loading loading.*;
-    } else try .init(alloc, cmd, storage.image_limits);
+    } else try .init(io, alloc, cmd, storage.image_limits);
 
     // We only want to deinit on error. If we're chunking, then we don't
     // want to deinit at all. If we're not chunking, then we'll deinit
@@ -362,7 +369,7 @@ fn loadAndAddImage(
     // Validate and store our image
     var img = try loading.complete(alloc);
     errdefer img.deinit(alloc);
-    try storage.addImage(alloc, img);
+    try storage.addImage(io, alloc, img);
 
     // Get our display settings
     const display_ = loading.display;
@@ -396,8 +403,9 @@ fn encodeError(r: *Response, err: EncodeableError) void {
 test "kittygfx more chunks with q=1" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Initial chunk has q=1
@@ -407,7 +415,7 @@ test "kittygfx more chunks with q=1" {
             "a=T,f=24,t=d,i=1,s=1,v=2,c=10,r=1,m=1,q=1;////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
 
@@ -418,7 +426,7 @@ test "kittygfx more chunks with q=1" {
             "m=0;////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
 }
@@ -426,8 +434,9 @@ test "kittygfx more chunks with q=1" {
 test "kittygfx more chunks with q=0" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Initial chunk has q=0
@@ -437,7 +446,7 @@ test "kittygfx more chunks with q=0" {
             "a=t,f=24,t=d,s=1,v=2,c=10,r=1,m=1,i=1,q=0;////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
 
@@ -448,7 +457,7 @@ test "kittygfx more chunks with q=0" {
             "m=0;////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd).?;
+        const resp = execute(io, alloc, &t, &cmd).?;
         try testing.expect(resp.ok());
     }
 }
@@ -456,8 +465,9 @@ test "kittygfx more chunks with q=0" {
 test "kittygfx more chunks with chunk increasing q" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     // Initial chunk has q=0
@@ -467,7 +477,7 @@ test "kittygfx more chunks with chunk increasing q" {
             "a=t,f=24,t=d,s=1,v=2,c=10,r=1,m=1,i=1,q=0;////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
 
@@ -478,7 +488,7 @@ test "kittygfx more chunks with chunk increasing q" {
             "m=0,q=1;////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
 }
@@ -486,8 +496,9 @@ test "kittygfx more chunks with chunk increasing q" {
 test "kittygfx default format is rgba" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     const cmd = try command.Parser.parseString(
@@ -495,7 +506,7 @@ test "kittygfx default format is rgba" {
         "a=t,t=d,i=1,s=1,v=2,c=10,r=1;///////////",
     );
     defer cmd.deinit(alloc);
-    const resp = execute(alloc, &t, &cmd).?;
+    const resp = execute(io, alloc, &t, &cmd).?;
     try testing.expect(resp.ok());
 
     const storage = &t.screens.active.kitty_images;
@@ -506,8 +517,9 @@ test "kittygfx default format is rgba" {
 test "kittygfx test valid u32 (expect invalid image ID)" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     const cmd = try command.Parser.parseString(
@@ -515,7 +527,7 @@ test "kittygfx test valid u32 (expect invalid image ID)" {
         "a=p,i=4294967295",
     );
     defer cmd.deinit(alloc);
-    const resp = execute(alloc, &t, &cmd).?;
+    const resp = execute(io, alloc, &t, &cmd).?;
     try testing.expect(!resp.ok());
     try testing.expectEqual(resp.message, "ENOENT: image not found");
 }
@@ -523,8 +535,9 @@ test "kittygfx test valid u32 (expect invalid image ID)" {
 test "kittygfx test valid i32 (expect invalid image ID)" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     const cmd = try command.Parser.parseString(
@@ -532,7 +545,7 @@ test "kittygfx test valid i32 (expect invalid image ID)" {
         "a=p,i=1,z=-2147483648",
     );
     defer cmd.deinit(alloc);
-    const resp = execute(alloc, &t, &cmd).?;
+    const resp = execute(io, alloc, &t, &cmd).?;
     try testing.expect(!resp.ok());
     try testing.expectEqual(resp.message, "ENOENT: image not found");
 }
@@ -540,8 +553,9 @@ test "kittygfx test valid i32 (expect invalid image ID)" {
 test "kittygfx no response with no image ID or number" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     {
@@ -550,7 +564,7 @@ test "kittygfx no response with no image ID or number" {
             "a=t,f=24,t=d,s=1,v=2,c=10,r=1,i=0,I=0;////////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
 }
@@ -558,8 +572,9 @@ test "kittygfx no response with no image ID or number" {
 test "kittygfx no response with no image ID or number load and display" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
 
     {
@@ -568,16 +583,17 @@ test "kittygfx no response with no image ID or number load and display" {
             "a=T,f=24,t=d,s=1,v=2,c=10,r=1,i=0,I=0;////////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
 }
 
 test "kittygfx retransmit same id gets fresh image generation" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     const storage = &t.screens.active.kitty_images;
 
@@ -588,7 +604,7 @@ test "kittygfx retransmit same id gets fresh image generation" {
             "a=t,t=d,f=24,i=1,s=1,v=2;////////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd).?;
+        const resp = execute(io, alloc, &t, &cmd).?;
         try testing.expect(resp.ok());
     }
     const gen1 = storage.imageById(1).?.generation;
@@ -604,7 +620,7 @@ test "kittygfx retransmit same id gets fresh image generation" {
             "a=t,t=d,f=24,i=1,s=1,v=2;AAAAAAAA",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd).?;
+        const resp = execute(io, alloc, &t, &cmd).?;
         try testing.expect(resp.ok());
     }
     const gen2 = storage.imageById(1).?.generation;
@@ -614,9 +630,10 @@ test "kittygfx retransmit same id gets fresh image generation" {
 
 test "kittygfx delete then retransmit same id gets fresh generation" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
 
-    var t = try Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    var t = try Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     const storage = &t.screens.active.kitty_images;
 
@@ -628,7 +645,7 @@ test "kittygfx delete then retransmit same id gets fresh generation" {
             "a=T,t=d,f=24,i=1,s=1,v=2,c=1,r=1;////////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd).?;
+        const resp = execute(io, alloc, &t, &cmd).?;
         try testing.expect(resp.ok());
     }
     const gen1 = storage.imageById(1).?.generation;
@@ -636,7 +653,7 @@ test "kittygfx delete then retransmit same id gets fresh generation" {
     {
         const cmd = try command.Parser.parseString(alloc, "a=d,d=A");
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd);
+        const resp = execute(io, alloc, &t, &cmd);
         try testing.expect(resp == null);
     }
     try testing.expect(storage.imageById(1) == null);
@@ -649,7 +666,7 @@ test "kittygfx delete then retransmit same id gets fresh generation" {
             "a=t,t=d,f=24,i=1,s=1,v=2;////////",
         );
         defer cmd.deinit(alloc);
-        const resp = execute(alloc, &t, &cmd).?;
+        const resp = execute(io, alloc, &t, &cmd).?;
         try testing.expect(resp.ok());
     }
     const gen2 = storage.imageById(1).?.generation;
diff --git a/src/terminal/kitty/graphics_image.zig b/src/terminal/kitty/graphics_image.zig
index b66389630..ef584c09a 100644
--- a/src/terminal/kitty/graphics_image.zig
+++ b/src/terminal/kitty/graphics_image.zig
@@ -10,12 +10,6 @@ const command = @import("graphics_command.zig");
 const PageList = @import("../PageList.zig");
 const sys = @import("../sys.zig");
 
-const temp_dir = struct {
-    const TempDir = @import("../../os/TempDir.zig");
-    const allocTmpDir = @import("../../os/file.zig").allocTmpDir;
-    const freeTmpDir = @import("../../os/file.zig").freeTmpDir;
-};
-
 const log = std.log.scoped(.kitty_gfx);
 
 /// Maximum width or height of an image. Taken directly from Kitty.
@@ -34,7 +28,7 @@ pub const LoadingImage = struct {
     image: Image,
 
     /// The data that is being built up.
-    data: std.ArrayListUnmanaged(u8) = .{},
+    data: std.ArrayListUnmanaged(u8) = .empty,
 
     /// This is non-null when a transmit and display command is given
     /// so that we display the image after it is fully loaded.
@@ -44,26 +38,41 @@ pub const LoadingImage = struct {
     /// used if q isn't set on subsequent chunks.
     quiet: command.Command.Quiet,
 
+    /// The temporary directory for file transmission (null means that
+    /// temporary directory transmission is disabled).
+    temporary_directory: ?[]const u8,
+
     /// The limits of the Kitty Graphics protocol we should allow.
     ///
     /// This can be used to restrict the type of images and other
     /// parameters for resource or security reasons. Note that depending
     /// on how libghostty is compiled, some of these may be fully unsupported
     /// and ignored (e.g. "file" on wasm32-freestanding).
-    pub const Limits = packed struct {
+    pub const Limits = struct {
         file: bool,
-        temporary_file: bool,
+        temporary_file: union(enum) {
+            enabled: struct {
+                /// The directory to expect temporary files in.
+                directory: []const u8,
+            },
+            disabled: void,
+        },
         shared_memory: bool,
 
-        pub const all: Limits = .{
-            .file = true,
-            .temporary_file = true,
-            .shared_memory = true,
-        };
+        /// Enables all filesystem-related image transmission mediums. `path`
+        /// is the temporary directory to expect files in when files are
+        /// transmitted using said medium.
+        pub fn allWithTempDir(path: []const u8) Limits {
+            return .{
+                .file = true,
+                .temporary_file = .{ .enabled = .{ .directory = path } },
+                .shared_memory = true,
+            };
+        }
 
         pub const direct: Limits = .{
             .file = false,
-            .temporary_file = false,
+            .temporary_file = .disabled,
             .shared_memory = false,
         };
     };
@@ -72,6 +81,7 @@ pub const LoadingImage = struct {
     /// If this is a multi-chunk image, this should only be the FIRST
     /// chunk.
     pub fn init(
+        io: std.Io,
         alloc: Allocator,
         cmd: *const command.Command,
         limits: Limits,
@@ -93,6 +103,10 @@ pub const LoadingImage = struct {
 
             .display = cmd.display(),
             .quiet = cmd.quiet,
+            .temporary_directory = switch (limits.temporary_file) {
+                .enabled => |d| d.directory,
+                .disabled => null,
+            },
         };
 
         // Special case for the direct medium, we just add the chunk directly.
@@ -116,7 +130,7 @@ pub const LoadingImage = struct {
             switch (t.medium) {
                 .direct => unreachable,
                 .file => if (!limits.file) return error.UnsupportedMedium,
-                .temporary_file => if (!limits.temporary_file) return error.UnsupportedMedium,
+                .temporary_file => if (limits.temporary_file == .disabled) return error.UnsupportedMedium,
                 .shared_memory => if (!limits.shared_memory) return error.UnsupportedMedium,
             }
         }
@@ -135,9 +149,16 @@ pub const LoadingImage = struct {
         var abs_buf: [std.fs.max_path_bytes]u8 = undefined;
         const path = switch (t.medium) {
             .direct => unreachable, // handled above
-            .file, .temporary_file => posix.realpath(cmd.data, &abs_buf) catch |err| {
-                log.warn("failed to get absolute path: {}", .{err});
-                return error.InvalidData;
+            .file, .temporary_file => path: {
+                const len = std.Io.Dir.cwd().realPathFile(
+                    io,
+                    cmd.data,
+                    &abs_buf,
+                ) catch |err| {
+                    log.warn("failed to get absolute path: {}", .{err});
+                    return error.InvalidData;
+                };
+                break :path abs_buf[0..len];
             },
             .shared_memory => cmd.data,
         };
@@ -145,9 +166,9 @@ pub const LoadingImage = struct {
         // Depending on the medium, load the data from the path.
         switch (t.medium) {
             .direct => unreachable, // handled above
-            .file => try result.readFile(.file, alloc, t, path),
-            .temporary_file => try result.readFile(.temporary_file, alloc, t, path),
-            .shared_memory => try result.readSharedMemory(alloc, t, path),
+            .file => try result.readFile(.file, io, alloc, t, path),
+            .temporary_file => try result.readFile(.temporary_file, io, alloc, t, path),
+            .shared_memory => try result.readSharedMemory(io, alloc, t, path),
         }
 
         return result;
@@ -156,6 +177,7 @@ pub const LoadingImage = struct {
     /// Reads the data from a shared memory segment.
     fn readSharedMemory(
         self: *LoadingImage,
+        io: std.Io,
         alloc: Allocator,
         t: command.Transmission,
         path: []const u8,
@@ -176,7 +198,7 @@ pub const LoadingImage = struct {
         var buf: [std.fs.max_path_bytes]u8 = undefined;
         const pathz = std.fmt.bufPrintZ(&buf, "{s}", .{path}) catch return error.InvalidData;
 
-        const fd = std.c.shm_open(pathz, @as(c_int, @bitCast(std.c.O{ .ACCMODE = .RDONLY })), 0);
+        const fd = std.c.shm_open(pathz, @as(c_int, @bitCast(std.c.O{ .ACCMODE = .RDONLY })), @as(u16, 0));
         switch (std.posix.errno(fd)) {
             .SUCCESS => {},
             else => |err| {
@@ -184,13 +206,18 @@ pub const LoadingImage = struct {
                 return error.InvalidData;
             },
         }
-        defer _ = std.c.close(fd);
+        const file: std.Io.File = .{
+            .handle = fd,
+            .flags = .{ .nonblocking = false },
+        };
+
+        defer file.close(io);
         defer _ = std.c.shm_unlink(pathz);
 
         // The size from stat on may be larger than our expected size because
         // shared memory has to be a multiple of the page size.
         const stat_size: usize = stat: {
-            const stat = std.posix.fstat(fd) catch |err| {
+            const stat = file.stat(io) catch |err| {
                 log.warn("unable to fstat shared memory {s}: {}", .{ path, err });
                 return error.InvalidData;
             };
@@ -223,7 +250,7 @@ pub const LoadingImage = struct {
         const map = std.posix.mmap(
             null,
             stat_size, // mmap always uses the stat size
-            std.c.PROT.READ,
+            .{ .READ = true },
             std.c.MAP{ .TYPE = .SHARED },
             fd,
             0,
@@ -252,6 +279,7 @@ pub const LoadingImage = struct {
     fn readFile(
         self: *LoadingImage,
         comptime medium: command.Transmission.Medium,
+        io: std.Io,
         alloc: Allocator,
         t: command.Transmission,
         path: []const u8,
@@ -273,25 +301,26 @@ pub const LoadingImage = struct {
 
         // Temporary file logic
         if (medium == .temporary_file) {
-            if (!isPathInTempDir(path)) return error.TemporaryFileNotInTempDir;
+            assert(self.temporary_directory != null);
+            if (!isPathInTempDir(io, self.temporary_directory.?, path)) return error.TemporaryFileNotInTempDir;
             if (std.mem.indexOf(u8, path, "tty-graphics-protocol") == null) {
                 return error.TemporaryFileNotNamedCorrectly;
             }
         }
         defer if (medium == .temporary_file) {
-            posix.unlink(path) catch |err| {
+            std.Io.Dir.cwd().deleteFile(io, path) catch |err| {
                 log.warn("failed to delete temporary file: {}", .{err});
             };
         };
 
-        var file = std.fs.cwd().openFile(path, .{}) catch |err| {
+        var file = std.Io.Dir.cwd().openFile(io, path, .{}) catch |err| {
             log.warn("failed to open temporary file: {}", .{err});
             return error.InvalidData;
         };
-        defer file.close();
+        defer file.close(io);
 
         // File must be a regular file
-        if (file.stat()) |stat| {
+        if (file.stat(io)) |stat| {
             if (stat.kind != .file) {
                 log.warn("file is not a regular file kind={}", .{stat.kind});
                 return error.InvalidData;
@@ -301,15 +330,14 @@ pub const LoadingImage = struct {
             return error.InvalidData;
         }
 
+        var buf: [4096]u8 = undefined;
+        var buf_reader = file.reader(io, &buf);
         if (t.offset > 0) {
-            file.seekTo(@intCast(t.offset)) catch |err| {
+            buf_reader.seekTo(@intCast(t.offset)) catch |err| {
                 log.warn("failed to seek to offset {}: {}", .{ t.offset, err });
                 return error.InvalidData;
             };
         }
-
-        var buf: [4096]u8 = undefined;
-        var buf_reader = file.reader(&buf);
         const reader = &buf_reader.interface;
 
         // Read the file
@@ -328,19 +356,20 @@ pub const LoadingImage = struct {
 
     /// Returns true if path appears to be in a temporary directory.
     /// Copies logic from Kitty.
-    fn isPathInTempDir(path: []const u8) bool {
+    fn isPathInTempDir(io: std.Io, dir: []const u8, path: []const u8) bool {
         if (std.mem.startsWith(u8, path, "/tmp")) return true;
         if (std.mem.startsWith(u8, path, "/dev/shm")) return true;
-        const dir = temp_dir.allocTmpDir(std.heap.page_allocator) catch return false;
-        defer temp_dir.freeTmpDir(std.heap.page_allocator, dir);
         if (std.mem.startsWith(u8, path, dir)) return true;
 
         // The temporary dir is sometimes a symlink. On macOS for
         // example /tmp is /private/var/...
         var buf: [std.fs.max_path_bytes]u8 = undefined;
-        if (posix.realpath(dir, &buf)) |real_dir| {
-            if (std.mem.startsWith(u8, path, real_dir)) return true;
-        } else |_| {}
+        const real_dir = buf[0 .. std.Io.Dir.cwd().realPathFile(
+            io,
+            dir,
+            &buf,
+        ) catch return false];
+        if (std.mem.startsWith(u8, path, real_dir)) return true;
 
         return false;
     }
@@ -412,7 +441,7 @@ pub const LoadingImage = struct {
 
     /// Debug function to write the data to a file. This is useful for
     /// capturing some test data for unit tests.
-    pub fn debugDump(self: LoadingImage) !void {
+    pub fn debugDump(io: std.Io, self: LoadingImage) !void {
         if (comptime builtin.mode != .Debug) @compileError("debugDump in non-debug");
 
         var buf: [1024]u8 = undefined;
@@ -427,9 +456,9 @@ pub const LoadingImage = struct {
                 self.image.id,
             },
         );
-        const cwd = std.fs.cwd();
-        const f = try cwd.createFile(filename, .{});
-        defer f.close();
+        const cwd = std.Io.Dir.cwd();
+        const f = try cwd.createFile(io, filename, .{});
+        defer f.close(io);
 
         const writer = f.writer();
         try writer.writeAll(self.data.items);
@@ -487,7 +516,7 @@ pub const LoadingImage = struct {
 
         // Replace our data
         self.data.deinit(alloc);
-        self.data = .{};
+        self.data = .empty;
         try self.data.ensureUnusedCapacity(alloc, result.data.len);
         try self.data.appendSlice(alloc, result.data[0..result.data.len]);
 
@@ -567,6 +596,7 @@ pub const Rect = struct {
 test "image load with invalid RGB data" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // <ESC>_Gi=31,s=1,v=1,a=q,t=d,f=24;AAAA<ESC>\
     var cmd: command.Command = .{
@@ -579,13 +609,14 @@ test "image load with invalid RGB data" {
         .data = try alloc.dupe(u8, "AAAA"),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
 }
 
 test "image load with image too wide" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -597,7 +628,7 @@ test "image load with image too wide" {
         .data = try alloc.dupe(u8, "AAAA"),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
     try testing.expectError(error.DimensionsTooLarge, loading.complete(alloc));
 }
@@ -605,6 +636,7 @@ test "image load with image too wide" {
 test "image load with image too tall" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -616,7 +648,7 @@ test "image load with image too tall" {
         .data = try alloc.dupe(u8, "AAAA"),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
     try testing.expectError(error.DimensionsTooLarge, loading.complete(alloc));
 }
@@ -624,6 +656,7 @@ test "image load with image too tall" {
 test "image load: rgb, zlib compressed, direct" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -640,7 +673,7 @@ test "image load: rgb, zlib compressed, direct" {
         ),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
     var img = try loading.complete(alloc);
     defer img.deinit(alloc);
@@ -652,6 +685,7 @@ test "image load: rgb, zlib compressed, direct" {
 test "image load: rgb, not compressed, direct" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -668,7 +702,7 @@ test "image load: rgb, not compressed, direct" {
         ),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
     var img = try loading.complete(alloc);
     defer img.deinit(alloc);
@@ -680,6 +714,7 @@ test "image load: rgb, not compressed, direct" {
 test "image load: rgb, zlib compressed, direct, chunked" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     const data = @embedFile("testdata/image-rgb-zlib_deflate-128x96-2147483647-raw.data");
 
@@ -697,13 +732,13 @@ test "image load: rgb, zlib compressed, direct, chunked" {
         .data = try alloc.dupe(u8, data[0..1024]),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
 
     // Read our remaining chunks
-    var fbs = std.io.fixedBufferStream(data[1024..]);
+    var fbs: std.Io.Reader = .fixed(data[1024..]);
     var buf: [1024]u8 = undefined;
-    while (fbs.reader().readAll(&buf)) |size| {
+    while (fbs.readSliceShort(&buf)) |size| {
         try loading.addData(alloc, buf[0..size]);
         if (size < buf.len) break;
     } else |err| return err;
@@ -717,6 +752,7 @@ test "image load: rgb, zlib compressed, direct, chunked" {
 test "image load: rgb, zlib compressed, direct, chunked with zero initial chunk" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     const data = @embedFile("testdata/image-rgb-zlib_deflate-128x96-2147483647-raw.data");
 
@@ -733,13 +769,13 @@ test "image load: rgb, zlib compressed, direct, chunked with zero initial chunk"
         } },
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
 
     // Read our remaining chunks
-    var fbs = std.io.fixedBufferStream(data);
+    var fbs: std.Io.Reader = .fixed(data);
     var buf: [1024]u8 = undefined;
-    while (fbs.reader().readAll(&buf)) |size| {
+    while (fbs.readSliceShort(&buf)) |size| {
         try loading.addData(alloc, buf[0..size]);
         if (size < buf.len) break;
     } else |err| return err;
@@ -753,17 +789,18 @@ test "image load: rgb, zlib compressed, direct, chunked with zero initial chunk"
 test "image load: temporary file without correct path" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -777,26 +814,33 @@ test "image load: temporary file without correct path" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    try testing.expectError(error.TemporaryFileNotNamedCorrectly, LoadingImage.init(alloc, &cmd, .all));
+    var dir_path_buf: [std.fs.max_path_bytes]u8 = undefined;
+    try testing.expectError(error.TemporaryFileNotNamedCorrectly, LoadingImage.init(
+        io,
+        alloc,
+        &cmd,
+        .allWithTempDir(dir_path_buf[0..try tmp_dir.dir.realPath(testing.io, &dir_path_buf)]),
+    ));
 
     // Temporary file should still be there
-    try tmp_dir.dir.access(path, .{});
+    try tmp_dir.dir.access(testing.io, path, .{});
 }
 
 test "image load: rgb, not compressed, temporary file" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "tty-graphics-protocol-image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("tty-graphics-protocol-image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "tty-graphics-protocol-image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -810,30 +854,37 @@ test "image load: rgb, not compressed, temporary file" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .all);
+    var dir_path_buf: [std.fs.max_path_bytes]u8 = undefined;
+    var loading = try LoadingImage.init(
+        io,
+        alloc,
+        &cmd,
+        .allWithTempDir(dir_path_buf[0..try tmp_dir.dir.realPath(testing.io, &dir_path_buf)]),
+    );
     defer loading.deinit(alloc);
     var img = try loading.complete(alloc);
     defer img.deinit(alloc);
     try testing.expect(img.compression == .none);
 
     // Temporary file should be gone
-    try testing.expectError(error.FileNotFound, tmp_dir.dir.access(path, .{}));
+    try testing.expectError(error.FileNotFound, tmp_dir.dir.access(testing.io, path, .{}));
 }
 
 test "image load: rgb, not compressed, regular file" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -847,12 +898,58 @@ test "image load: rgb, not compressed, regular file" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .all);
+    var dir_path_buf: [std.fs.max_path_bytes]u8 = undefined;
+    var loading = try LoadingImage.init(
+        io,
+        alloc,
+        &cmd,
+        .allWithTempDir(dir_path_buf[0..try tmp_dir.dir.realPath(testing.io, &dir_path_buf)]),
+    );
+    defer loading.deinit(alloc);
+    var img = try loading.complete(alloc);
+    defer img.deinit(alloc);
+    try testing.expect(img.compression == .none);
+    try tmp_dir.dir.access(testing.io, path, .{});
+}
+
+test "image load: rgb, not compressed, relative regular file" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+    const io = testing.io;
+
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
+    const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
+    try tmp_dir.dir.writeFile(testing.io, .{
+        .sub_path = "image.data",
+        .data = data,
+    });
+
+    var cmd: command.Command = .{
+        .control = .{ .transmit = .{
+            .format = .rgb,
+            .medium = .file,
+            .compression = .none,
+            .width = 20,
+            .height = 15,
+            .image_id = 31,
+        } },
+        .data = try std.fmt.allocPrint(
+            alloc,
+            ".zig-cache/tmp/{s}/image.data",
+            .{tmp_dir.sub_path},
+        ),
+    };
+    defer cmd.deinit(alloc);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .{
+        .file = true,
+        .temporary_file = .disabled,
+        .shared_memory = false,
+    });
     defer loading.deinit(alloc);
     var img = try loading.complete(alloc);
     defer img.deinit(alloc);
     try testing.expect(img.compression == .none);
-    try tmp_dir.dir.access(path, .{});
 }
 
 test "image load: png, not compressed, regular file" {
@@ -860,17 +957,18 @@ test "image load: png, not compressed, regular file" {
 
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-png-none-50x76-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "tty-graphics-protocol-image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("tty-graphics-protocol-image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "tty-graphics-protocol-image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -884,18 +982,25 @@ test "image load: png, not compressed, regular file" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .all);
+    var dir_path_buf: [std.fs.max_path_bytes]u8 = undefined;
+    var loading = try LoadingImage.init(
+        io,
+        alloc,
+        &cmd,
+        .allWithTempDir(dir_path_buf[0..try tmp_dir.dir.realPath(testing.io, &dir_path_buf)]),
+    );
     defer loading.deinit(alloc);
     var img = try loading.complete(alloc);
     defer img.deinit(alloc);
     try testing.expect(img.compression == .none);
     try testing.expect(img.format == .rgba);
-    try tmp_dir.dir.access(path, .{});
+    try tmp_dir.dir.access(testing.io, path, .{});
 }
 
 test "limits: direct medium always allowed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -910,24 +1015,25 @@ test "limits: direct medium always allowed" {
     defer cmd.deinit(alloc);
 
     // Direct medium should work even with the most restrictive limits
-    var loading = try LoadingImage.init(alloc, &cmd, .direct);
+    var loading = try LoadingImage.init(io, alloc, &cmd, .direct);
     defer loading.deinit(alloc);
 }
 
 test "limits: file medium blocked by limits" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -941,23 +1047,24 @@ test "limits: file medium blocked by limits" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    try testing.expectError(error.UnsupportedMedium, LoadingImage.init(alloc, &cmd, .direct));
+    try testing.expectError(error.UnsupportedMedium, LoadingImage.init(io, alloc, &cmd, .direct));
 }
 
 test "limits: file medium allowed by limits" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -971,9 +1078,9 @@ test "limits: file medium allowed by limits" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .{
+    var loading = try LoadingImage.init(io, alloc, &cmd, .{
         .file = true,
-        .temporary_file = false,
+        .temporary_file = .disabled,
         .shared_memory = false,
     });
     defer loading.deinit(alloc);
@@ -982,17 +1089,18 @@ test "limits: file medium allowed by limits" {
 test "limits: temporary file medium blocked by limits" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "tty-graphics-protocol-image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("tty-graphics-protocol-image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "tty-graphics-protocol-image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -1006,30 +1114,31 @@ test "limits: temporary file medium blocked by limits" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    try testing.expectError(error.UnsupportedMedium, LoadingImage.init(alloc, &cmd, .{
+    try testing.expectError(error.UnsupportedMedium, LoadingImage.init(io, alloc, &cmd, .{
         .file = true,
-        .temporary_file = false,
+        .temporary_file = .disabled,
         .shared_memory = true,
     }));
 
     // File should still exist since we blocked before reading
-    try tmp_dir.dir.access("tty-graphics-protocol-image.data", .{});
+    try tmp_dir.dir.access(testing.io, "tty-graphics-protocol-image.data", .{});
 }
 
 test "limits: temporary file medium allowed by limits" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var tmp_dir = try temp_dir.TempDir.init();
-    defer tmp_dir.deinit();
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
     const data = @embedFile("testdata/image-rgb-none-20x15-2147483647-raw.data");
-    try tmp_dir.dir.writeFile(.{
+    try tmp_dir.dir.writeFile(testing.io, .{
         .sub_path = "tty-graphics-protocol-image.data",
         .data = data,
     });
 
     var buf: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try tmp_dir.dir.realpath("tty-graphics-protocol-image.data", &buf);
+    const path = buf[0..try tmp_dir.dir.realPathFile(testing.io, "tty-graphics-protocol-image.data", &buf)];
 
     var cmd: command.Command = .{
         .control = .{ .transmit = .{
@@ -1043,10 +1152,19 @@ test "limits: temporary file medium allowed by limits" {
         .data = try alloc.dupe(u8, path),
     };
     defer cmd.deinit(alloc);
-    var loading = try LoadingImage.init(alloc, &cmd, .{
-        .file = false,
-        .temporary_file = true,
-        .shared_memory = false,
-    });
+    var dir_path_buf: [std.fs.max_path_bytes]u8 = undefined;
+    var loading = try LoadingImage.init(
+        io,
+        alloc,
+        &cmd,
+
+        .{
+            .file = false,
+            .temporary_file = .{
+                .enabled = .{ .directory = dir_path_buf[0..try tmp_dir.dir.realPath(testing.io, &dir_path_buf)] },
+            },
+            .shared_memory = false,
+        },
+    );
     defer loading.deinit(alloc);
 }
diff --git a/src/terminal/kitty/graphics_storage.zig b/src/terminal/kitty/graphics_storage.zig
index 6da0f5744..2a9ad7f56 100644
--- a/src/terminal/kitty/graphics_storage.zig
+++ b/src/terminal/kitty/graphics_storage.zig
@@ -32,8 +32,8 @@ var generation_counter: GenerationCounter = .{};
 /// Returns the next generation stamp. Stamps are unique and strictly
 /// monotonically increasing process-wide, starting at 1 (0 is reserved
 /// to mean "never stamped").
-pub fn nextGeneration() u64 {
-    return generation_counter.next();
+pub fn nextGeneration(io: std.Io) u64 {
+    return generation_counter.next(io);
 }
 
 /// Backing implementation for the generation counter. We use a
@@ -48,16 +48,17 @@ pub fn nextGeneration() u64 {
 const GenerationCounter = if (@bitSizeOf(usize) >= 64) struct {
     value: std.atomic.Value(u64) = .init(0),
 
-    fn next(self: *@This()) u64 {
+    fn next(self: *@This(), io: std.Io) u64 {
+        _ = io;
         return self.value.fetchAdd(1, .monotonic) + 1;
     }
 } else struct {
-    mutex: std.Thread.Mutex = .{},
+    mutex: std.Io.Mutex = .init,
     value: u64 = 0,
 
-    fn next(self: *@This()) u64 {
-        self.mutex.lock();
-        defer self.mutex.unlock();
+    fn next(self: *@This(), io: std.Io) u64 {
+        self.mutex.lockUncancelable(io);
+        defer self.mutex.unlock(io);
         self.value += 1;
         return self.value;
     }
@@ -159,9 +160,9 @@ pub const ImageStorage = struct {
     /// screen switches); those must set only the dirty flag directly.
     /// Bumping the generation for geometry changes would break the
     /// contract that an unchanged generation means unchanged contents.
-    fn markMutated(self: *ImageStorage) void {
+    fn markMutated(self: *ImageStorage, io: std.Io) void {
         self.dirty = true;
-        self.generation = nextGeneration();
+        self.generation = nextGeneration(io);
     }
 
     /// Sets the limit in bytes for the total amount of image data that
@@ -170,6 +171,7 @@ pub const ImageStorage = struct {
     /// be disabled.
     pub fn setLimit(
         self: *ImageStorage,
+        io: std.Io,
         alloc: Allocator,
         s: *terminal.Screen,
         limit: usize,
@@ -179,14 +181,14 @@ pub const ImageStorage = struct {
             const image_limits = self.image_limits;
             self.deinit(alloc, s);
             self.* = .{ .image_limits = image_limits };
-            self.markMutated();
+            self.markMutated(io);
         }
 
         // If we re lowering our limit, check if we need to evict.
         if (limit < self.total_bytes) {
             const req_bytes = self.total_bytes - limit;
             log.info("evicting images to lower limit, evicting={}", .{req_bytes});
-            if (!try self.evictImage(alloc, req_bytes)) {
+            if (!try self.evictImage(io, alloc, req_bytes)) {
                 log.warn("failed to evict enough images for required bytes", .{});
             }
         }
@@ -196,7 +198,7 @@ pub const ImageStorage = struct {
 
     /// Add an already-loaded image to the storage. This will automatically
     /// free any existing image with the same ID.
-    pub fn addImage(self: *ImageStorage, alloc: Allocator, img: Image) Allocator.Error!void {
+    pub fn addImage(self: *ImageStorage, io: std.Io, alloc: Allocator, img: Image) Allocator.Error!void {
         // If the image itself is over the limit, then error immediately
         if (img.data.len > self.total_limit) return error.OutOfMemory;
 
@@ -205,7 +207,7 @@ pub const ImageStorage = struct {
         if (total_bytes > self.total_limit) {
             const req_bytes = total_bytes - self.total_limit;
             log.info("evicting images to make space for {} bytes", .{req_bytes});
-            if (!try self.evictImage(alloc, req_bytes)) {
+            if (!try self.evictImage(io, alloc, req_bytes)) {
                 log.warn("failed to evict enough images for required bytes", .{});
                 return error.OutOfMemory;
             }
@@ -233,7 +235,7 @@ pub const ImageStorage = struct {
         // every add/replace a unique stamp even when the same image ID
         // is retransmitted with identical dimensions, so consumers
         // (e.g. renderer texture caches) can detect content changes.
-        self.markMutated();
+        self.markMutated(io);
         gop.value_ptr.generation = self.generation;
     }
 
@@ -241,6 +243,7 @@ pub const ImageStorage = struct {
     /// the image exists to prevent memory corruption.
     pub fn addPlacement(
         self: *ImageStorage,
+        io: std.Io,
         alloc: Allocator,
         image_id: u32,
         placement_id: u32,
@@ -275,7 +278,7 @@ pub const ImageStorage = struct {
         const gop = try self.placements.getOrPut(alloc, key);
         gop.value_ptr.* = p;
 
-        self.markMutated();
+        self.markMutated(io);
     }
 
     fn clearPlacements(self: *ImageStorage, s: *terminal.Screen) void {
@@ -310,6 +313,7 @@ pub const ImageStorage = struct {
     /// Delete placements, images.
     pub fn delete(
         self: *ImageStorage,
+        io: std.Io,
         alloc: Allocator,
         t: *terminal.Terminal,
         cmd: command.Delete,
@@ -323,7 +327,7 @@ pub const ImageStorage = struct {
         const placements_before = self.placements.count();
         const images_before = self.images.count();
         defer if (self.placements.count() != placements_before or
-            self.images.count() != images_before) self.markMutated();
+            self.images.count() != images_before) self.markMutated(io);
 
         switch (cmd) {
             .all => |delete_images| {
@@ -599,7 +603,7 @@ pub const ImageStorage = struct {
     ///
     /// This will evict as many images as necessary to make space for
     /// req bytes.
-    fn evictImage(self: *ImageStorage, alloc: Allocator, req: usize) !bool {
+    fn evictImage(self: *ImageStorage, io: std.Io, alloc: Allocator, req: usize) !bool {
         assert(req <= self.total_limit);
 
         // Ironically we allocate to evict. We should probably redesign the
@@ -687,7 +691,7 @@ pub const ImageStorage = struct {
         // Evicting anything is a content mutation. This matters for the
         // setLimit path in particular, which doesn't otherwise mark it.
         var any_evicted = false;
-        defer if (any_evicted) self.markMutated();
+        defer if (any_evicted) self.markMutated(io);
 
         // They're in order of best to evict.
         var evicted: usize = 0;
@@ -930,17 +934,18 @@ fn trackPin(
 test "storage: add placement with zero placement id" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 100, .rows = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 100, .rows = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 50, .height = 50 });
-    try s.addImage(alloc, .{ .id = 2, .width = 25, .height = 25 });
-    try s.addPlacement(alloc, 1, 0, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
-    try s.addPlacement(alloc, 1, 0, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 50, .height = 50 });
+    try s.addImage(io, alloc, .{ .id = 2, .width = 25, .height = 25 });
+    try s.addPlacement(io, alloc, 1, 0, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
+    try s.addPlacement(io, alloc, 1, 0, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
 
     try testing.expectEqual(@as(usize, 2), s.placements.count());
     try testing.expectEqual(@as(usize, 2), s.images.count());
@@ -959,20 +964,21 @@ test "storage: add placement with zero placement id" {
 test "storage: delete all placements and images" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .all = true });
+    s.delete(io, alloc, &t, .{ .all = true });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 0), s.images.count());
     try testing.expectEqual(@as(usize, 0), s.placements.count());
@@ -982,21 +988,22 @@ test "storage: delete all placements and images" {
 test "storage: delete all placements and images preserves limit" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
     s.total_limit = 5000;
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .all = true });
+    s.delete(io, alloc, &t, .{ .all = true });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 0), s.images.count());
     try testing.expectEqual(@as(usize, 0), s.placements.count());
@@ -1007,20 +1014,21 @@ test "storage: delete all placements and images preserves limit" {
 test "storage: delete all placements" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .all = false });
+    s.delete(io, alloc, &t, .{ .all = false });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 0), s.placements.count());
     try testing.expectEqual(@as(usize, 3), s.images.count());
@@ -1030,20 +1038,21 @@ test "storage: delete all placements" {
 test "storage: delete all placements by image id" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .id = .{ .image_id = 2 } });
+    s.delete(io, alloc, &t, .{ .id = .{ .image_id = 2 } });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 1), s.placements.count());
     try testing.expectEqual(@as(usize, 3), s.images.count());
@@ -1053,20 +1062,21 @@ test "storage: delete all placements by image id" {
 test "storage: delete all placements by image id and unused images" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .id = .{ .delete = true, .image_id = 2 } });
+    s.delete(io, alloc, &t, .{ .id = .{ .delete = true, .image_id = 2 } });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 1), s.placements.count());
     try testing.expectEqual(@as(usize, 2), s.images.count());
@@ -1076,21 +1086,22 @@ test "storage: delete all placements by image id and unused images" {
 test "storage: delete placement by specific id" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .id = .{
+    s.delete(io, alloc, &t, .{ .id = .{
         .delete = true,
         .image_id = 1,
         .placement_id = 2,
@@ -1104,7 +1115,8 @@ test "storage: delete placement by specific id" {
 test "storage: delete intersecting cursor" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 100, .cols = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 100, .cols = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
@@ -1112,15 +1124,15 @@ test "storage: delete intersecting cursor" {
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 50, .height = 50 });
-    try s.addImage(alloc, .{ .id = 2, .width = 25, .height = 25 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 50, .height = 50 });
+    try s.addImage(io, alloc, .{ .id = 2, .width = 25, .height = 25 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
 
     t.screens.active.cursorAbsolute(12, 12);
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .intersect_cursor = false });
+    s.delete(io, alloc, &t, .{ .intersect_cursor = false });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 1), s.placements.count());
     try testing.expectEqual(@as(usize, 2), s.images.count());
@@ -1136,7 +1148,8 @@ test "storage: delete intersecting cursor" {
 test "storage: delete intersecting cursor plus unused" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 100, .cols = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 100, .cols = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
@@ -1144,15 +1157,15 @@ test "storage: delete intersecting cursor plus unused" {
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 50, .height = 50 });
-    try s.addImage(alloc, .{ .id = 2, .width = 25, .height = 25 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 50, .height = 50 });
+    try s.addImage(io, alloc, .{ .id = 2, .width = 25, .height = 25 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
 
     t.screens.active.cursorAbsolute(12, 12);
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .intersect_cursor = true });
+    s.delete(io, alloc, &t, .{ .intersect_cursor = true });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 1), s.placements.count());
     try testing.expectEqual(@as(usize, 2), s.images.count());
@@ -1168,7 +1181,8 @@ test "storage: delete intersecting cursor plus unused" {
 test "storage: delete intersecting cursor hits multiple" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 100, .cols = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 100, .cols = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
@@ -1176,15 +1190,15 @@ test "storage: delete intersecting cursor hits multiple" {
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 50, .height = 50 });
-    try s.addImage(alloc, .{ .id = 2, .width = 25, .height = 25 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 50, .height = 50 });
+    try s.addImage(io, alloc, .{ .id = 2, .width = 25, .height = 25 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
 
     t.screens.active.cursorAbsolute(26, 26);
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .intersect_cursor = true });
+    s.delete(io, alloc, &t, .{ .intersect_cursor = true });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 0), s.placements.count());
     try testing.expectEqual(@as(usize, 1), s.images.count());
@@ -1194,7 +1208,8 @@ test "storage: delete intersecting cursor hits multiple" {
 test "storage: delete by column" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 100, .cols = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 100, .cols = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
@@ -1202,13 +1217,13 @@ test "storage: delete by column" {
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 50, .height = 50 });
-    try s.addImage(alloc, .{ .id = 2, .width = 25, .height = 25 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 50, .height = 50 });
+    try s.addImage(io, alloc, .{ .id = 2, .width = 25, .height = 25 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .column = .{
+    s.delete(io, alloc, &t, .{ .column = .{
         .delete = false,
         .x = 60,
     } });
@@ -1227,19 +1242,20 @@ test "storage: delete by column" {
 test "storage: delete by column 1x1" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 100, .cols = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 100, .cols = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 1, .height = 1 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 3, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 2, .y = 0 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 1, .height = 1 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 3, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 2, .y = 0 }) } });
 
-    s.delete(alloc, &t, .{ .column = .{
+    s.delete(io, alloc, &t, .{ .column = .{
         .delete = false,
         .x = 2,
     } });
@@ -1260,7 +1276,8 @@ test "storage: delete by column 1x1" {
 test "storage: delete by row" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 100, .cols = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 100, .cols = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
@@ -1268,13 +1285,13 @@ test "storage: delete by row" {
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 50, .height = 50 });
-    try s.addImage(alloc, .{ .id = 2, .width = 25, .height = 25 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 50, .height = 50 });
+    try s.addImage(io, alloc, .{ .id = 2, .width = 25, .height = 25 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 0, .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 25, .y = 25 }) } });
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .row = .{
+    s.delete(io, alloc, &t, .{ .row = .{
         .delete = false,
         .y = 60,
     } });
@@ -1293,19 +1310,20 @@ test "storage: delete by row" {
 test "storage: delete by row 1x1" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 100, .cols = 100 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 100, .cols = 100 });
     defer t.deinit(alloc);
     t.width_px = 100;
     t.height_px = 100;
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1, .width = 1, .height = 1 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .y = 0 }) } });
-    try s.addPlacement(alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .y = 1 }) } });
-    try s.addPlacement(alloc, 1, 3, .{ .location = .{ .pin = try trackPin(&t, .{ .y = 2 }) } });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 1, .height = 1 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .y = 0 }) } });
+    try s.addPlacement(io, alloc, 1, 2, .{ .location = .{ .pin = try trackPin(&t, .{ .y = 1 }) } });
+    try s.addPlacement(io, alloc, 1, 3, .{ .location = .{ .pin = try trackPin(&t, .{ .y = 2 }) } });
 
-    s.delete(alloc, &t, .{ .row = .{
+    s.delete(io, alloc, &t, .{ .row = .{
         .delete = false,
         .y = 2,
     } });
@@ -1326,22 +1344,23 @@ test "storage: delete by row 1x1" {
 test "storage: delete images by range 1" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
     try testing.expectEqual(@as(usize, 3), s.images.count());
     try testing.expectEqual(@as(usize, 2), s.placements.count());
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .range = .{ .delete = false, .first = 1, .last = 2 } });
+    s.delete(io, alloc, &t, .{ .range = .{ .delete = false, .first = 1, .last = 2 } });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 3), s.images.count());
     try testing.expectEqual(@as(usize, 0), s.placements.count());
@@ -1351,22 +1370,23 @@ test "storage: delete images by range 1" {
 test "storage: delete images by range 2" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
     try testing.expectEqual(@as(usize, 3), s.images.count());
     try testing.expectEqual(@as(usize, 2), s.placements.count());
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .range = .{ .delete = true, .first = 1, .last = 2 } });
+    s.delete(io, alloc, &t, .{ .range = .{ .delete = true, .first = 1, .last = 2 } });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 1), s.images.count());
     try testing.expectEqual(@as(usize, 0), s.placements.count());
@@ -1376,22 +1396,23 @@ test "storage: delete images by range 2" {
 test "storage: delete images by range 3" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
     try testing.expectEqual(@as(usize, 3), s.images.count());
     try testing.expectEqual(@as(usize, 2), s.placements.count());
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .range = .{ .delete = false, .first = 1, .last = 1 } });
+    s.delete(io, alloc, &t, .{ .range = .{ .delete = false, .first = 1, .last = 1 } });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 3), s.images.count());
     try testing.expectEqual(@as(usize, 0), s.placements.count());
@@ -1401,22 +1422,23 @@ test "storage: delete images by range 3" {
 test "storage: delete images by range 4" {
     const testing = std.testing;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
     const tracked = t.screens.active.pages.countTrackedPins();
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addImage(alloc, .{ .id = 2 });
-    try s.addImage(alloc, .{ .id = 3 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
-    try s.addPlacement(alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 2 });
+    try s.addImage(io, alloc, .{ .id = 3 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 2, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
     try testing.expectEqual(@as(usize, 3), s.images.count());
     try testing.expectEqual(@as(usize, 2), s.placements.count());
 
     s.dirty = false;
-    s.delete(alloc, &t, .{ .range = .{ .delete = true, .first = 1, .last = 1 } });
+    s.delete(io, alloc, &t, .{ .range = .{ .delete = true, .first = 1, .last = 1 } });
     try testing.expect(s.dirty);
     try testing.expectEqual(@as(usize, 1), s.images.count());
     try testing.expectEqual(@as(usize, 0), s.placements.count());
@@ -1426,8 +1448,9 @@ test "storage: delete images by range 4" {
 test "storage: aspect ratio calculation when only columns or rows specified" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 100, .rows = 100 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 100, .rows = 100 });
     defer t.deinit(alloc);
     t.width_px = 1000; // 10 px per col
     t.height_px = 2000; // 20 px per row
@@ -1471,8 +1494,9 @@ test "storage: aspect ratio calculation when only columns or rows specified" {
 
 test "storage: generation stamps on image add and replace" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     var s: ImageStorage = .{};
@@ -1481,7 +1505,7 @@ test "storage: generation stamps on image add and replace" {
     // Fresh storage has generation zero (never mutated).
     try testing.expectEqual(@as(u64, 0), s.generation);
 
-    try s.addImage(alloc, .{ .id = 1, .width = 1, .height = 1 });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 1, .height = 1 });
     const gen1 = s.generation;
     try testing.expect(gen1 > 0);
 
@@ -1489,7 +1513,7 @@ test "storage: generation stamps on image add and replace" {
     try testing.expectEqual(gen1, img1.generation);
 
     // A second image gets a strictly greater stamp.
-    try s.addImage(alloc, .{ .id = 2, .width = 1, .height = 1 });
+    try s.addImage(io, alloc, .{ .id = 2, .width = 1, .height = 1 });
     const gen2 = s.generation;
     try testing.expect(gen2 > gen1);
     try testing.expectEqual(gen2, s.imageById(2).?.generation);
@@ -1497,7 +1521,7 @@ test "storage: generation stamps on image add and replace" {
     // Retransmitting the same image ID (identical dimensions) gets a
     // fresh stamp: this is what makes same-sized retransmissions
     // detectable by renderers.
-    try s.addImage(alloc, .{ .id = 1, .width = 1, .height = 1 });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 1, .height = 1 });
     const gen3 = s.generation;
     try testing.expect(gen3 > gen2);
     try testing.expectEqual(gen3, s.imageById(1).?.generation);
@@ -1508,16 +1532,17 @@ test "storage: generation stamps on image add and replace" {
 
 test "storage: generation bumps on placement and delete" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
-    try s.addImage(alloc, .{ .id = 1 });
+    try s.addImage(io, alloc, .{ .id = 1 });
     const gen_add = s.generation;
 
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
     const gen_place = s.generation;
     try testing.expect(gen_place > gen_add);
 
@@ -1526,26 +1551,27 @@ test "storage: generation bumps on placement and delete" {
     _ = s.imageByNumber(1);
     try testing.expectEqual(gen_place, s.generation);
 
-    s.delete(alloc, &t, .{ .all = true });
+    s.delete(io, alloc, &t, .{ .all = true });
     try testing.expect(s.generation > gen_place);
 }
 
 test "storage: generation bumps when setLimit evicts or disables" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
 
     const data = try alloc.dupe(u8, "1234");
-    try s.addImage(alloc, .{ .id = 1, .width = 1, .height = 1, .data = data });
+    try s.addImage(io, alloc, .{ .id = 1, .width = 1, .height = 1, .data = data });
     const gen_add = s.generation;
 
     // Lowering the limit evicts the image and must mark a mutation.
     s.dirty = false;
-    try s.setLimit(alloc, t.screens.active, 1);
+    try s.setLimit(io, alloc, t.screens.active, 1);
     try testing.expect(s.dirty);
     try testing.expect(s.generation > gen_add);
     try testing.expectEqual(@as(usize, 0), s.images.count());
@@ -1553,15 +1579,16 @@ test "storage: generation bumps when setLimit evicts or disables" {
 
     // Disabling (limit=0) resets the storage and must mark a mutation.
     s.dirty = false;
-    try s.setLimit(alloc, t.screens.active, 0);
+    try s.setLimit(io, alloc, t.screens.active, 0);
     try testing.expect(s.dirty);
     try testing.expect(s.generation > gen_evict);
 }
 
 test "storage: imageByNumber returns most recently transmitted" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     var s: ImageStorage = .{};
@@ -1569,27 +1596,28 @@ test "storage: imageByNumber returns most recently transmitted" {
 
     // Two images sharing a number: the newest transmission wins,
     // regardless of insertion order or clock resolution.
-    try s.addImage(alloc, .{ .id = 1, .number = 7 });
-    try s.addImage(alloc, .{ .id = 2, .number = 7 });
+    try s.addImage(io, alloc, .{ .id = 1, .number = 7 });
+    try s.addImage(io, alloc, .{ .id = 2, .number = 7 });
     try testing.expectEqual(@as(u32, 2), s.imageByNumber(7).?.id);
 
     // Retransmit the first: it becomes the newest.
-    try s.addImage(alloc, .{ .id = 1, .number = 7 });
+    try s.addImage(io, alloc, .{ .id = 1, .number = 7 });
     try testing.expectEqual(@as(u32, 1), s.imageByNumber(7).?.id);
 }
 
 test "storage: nextGeneration is unique and monotonic" {
     const testing = std.testing;
-    const a = nextGeneration();
-    const b = nextGeneration();
+    const a = nextGeneration(testing.io);
+    const b = nextGeneration(testing.io);
     try testing.expect(b > a);
     try testing.expect(a > 0);
 }
 
 test "storage: no-op delete does not mark a mutation" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     var s: ImageStorage = .{};
@@ -1597,50 +1625,52 @@ test "storage: no-op delete does not mark a mutation" {
 
     // A delete-all on an empty storage (this runs on every screen
     // clear) must not dirty the state or bump the generation.
-    s.delete(alloc, &t, .{ .all = true });
+    s.delete(io, alloc, &t, .{ .all = true });
     try testing.expect(!s.dirty);
     try testing.expectEqual(@as(u64, 0), s.generation);
 
     // Same for a delete that matches nothing.
-    try s.addImage(alloc, .{ .id = 1 });
-    try s.addPlacement(alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
+    try s.addImage(io, alloc, .{ .id = 1 });
+    try s.addPlacement(io, alloc, 1, 1, .{ .location = .{ .pin = try trackPin(&t, .{ .x = 1, .y = 1 }) } });
     const gen = s.generation;
     s.dirty = false;
-    s.delete(alloc, &t, .{ .id = .{ .image_id = 42 } });
+    s.delete(io, alloc, &t, .{ .id = .{ .image_id = 42 } });
     try testing.expect(!s.dirty);
     try testing.expectEqual(gen, s.generation);
 
     // But a delete that removes something does mark a mutation.
-    s.delete(alloc, &t, .{ .id = .{ .image_id = 1 } });
+    s.delete(io, alloc, &t, .{ .id = .{ .image_id = 1 } });
     try testing.expect(s.dirty);
     try testing.expect(s.generation > gen);
 }
 
 test "storage: evict unused transient image" {
     const testing = std.testing;
+    const io = testing.io;
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 3, .cols = 3 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 3, .cols = 3 });
     defer t.deinit(alloc);
 
     var s: ImageStorage = .{ .total_limit = 192 };
     defer s.deinit(alloc, t.screens.active);
 
-    try s.addImage(alloc, .{
+    try s.addImage(io, alloc, .{
         .id = 1,
         .data = try alloc.dupe(u8, "*" ** 64),
         .usage = .{ .transient = false },
     });
-    try s.addImage(alloc, .{
+    try s.addImage(io, alloc, .{
         .id = 2,
         .data = try alloc.dupe(u8, "*" ** 64),
         .usage = .{ .transient = true },
     });
-    try s.addImage(alloc, .{
+    try s.addImage(io, alloc, .{
         .id = 3,
         .data = try alloc.dupe(u8, "*" ** 64),
         .usage = .{ .transient = true },
     });
     try s.addPlacement(
+        io,
         alloc,
         2,
         1,
@@ -1648,7 +1678,7 @@ test "storage: evict unused transient image" {
     );
 
     const gen = s.generation;
-    const result = try s.evictImage(alloc, 32);
+    const result = try s.evictImage(io, alloc, 32);
     try testing.expect(s.dirty);
     try testing.expect(s.generation > gen);
     try testing.expectEqual(true, result);
diff --git a/src/terminal/kitty/graphics_unicode.zig b/src/terminal/kitty/graphics_unicode.zig
index a223797ba..dd1a6ce44 100644
--- a/src/terminal/kitty/graphics_unicode.zig
+++ b/src/terminal/kitty/graphics_unicode.zig
@@ -885,7 +885,8 @@ test "unicode diacritic" {
 
 test "unicode placement: none" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -900,7 +901,8 @@ test "unicode placement: none" {
 
 test "unicode placement: single row/col" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -924,7 +926,8 @@ test "unicode placement: single row/col" {
 
 test "unicode placement: continuation break" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 10 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 10 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -958,7 +961,8 @@ test "unicode placement: continuation break" {
 
 test "unicode placement: continuation with diacritics set" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 10 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 10 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -985,7 +989,8 @@ test "unicode placement: continuation with diacritics set" {
 
 test "unicode placement: continuation with no col" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 10 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 10 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -1012,7 +1017,8 @@ test "unicode placement: continuation with no col" {
 
 test "unicode placement: continuation with no diacritics" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 10 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 10 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -1039,7 +1045,8 @@ test "unicode placement: continuation with no diacritics" {
 
 test "unicode placement: run ending" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 10 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 10 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -1066,7 +1073,8 @@ test "unicode placement: run ending" {
 
 test "unicode placement: run starting in the middle" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 10 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 10 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -1093,7 +1101,8 @@ test "unicode placement: run starting in the middle" {
 
 test "unicode placement: specifying image id as palette" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -1118,7 +1127,8 @@ test "unicode placement: specifying image id as palette" {
 
 test "unicode placement: specifying image id with high bits" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -1143,7 +1153,8 @@ test "unicode placement: specifying image id with high bits" {
 
 test "unicode placement: specifying placement id as palette" {
     const alloc = testing.allocator;
-    var t = try terminal.Terminal.init(alloc, .{ .rows = 5, .cols = 5 });
+    const io = testing.io;
+    var t = try terminal.Terminal.init(io, alloc, .{ .rows = 5, .cols = 5 });
     defer t.deinit(alloc);
     t.modes.set(.grapheme_cluster, true);
 
@@ -1174,17 +1185,18 @@ test "unicode placement: specifying placement id as palette" {
 // printf "\033_Ga=p,i=1,U=1,q=2,c=4,r=2\033\\"
 test "unicode render placement: dog 4x2" {
     const alloc = testing.allocator;
+    const io = testing.io;
     const cell_width = 36;
     const cell_height = 80;
 
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 100, .rows = 100 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 100, .rows = 100 });
     defer t.deinit(alloc);
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
 
     const image: Image = .{ .id = 1, .width = 500, .height = 306 };
-    try s.addImage(alloc, image);
-    try s.addPlacement(alloc, 1, 0, .{
+    try s.addImage(io, alloc, image);
+    try s.addPlacement(io, alloc, 1, 0, .{
         .location = .{ .virtual = {} },
         .columns = 4,
         .rows = 2,
@@ -1241,17 +1253,18 @@ test "unicode render placement: dog 4x2" {
 // printf "\033_Ga=p,i=1,U=1,q=2,c=2,r=2\033\\"
 test "unicode render placement: dog 2x2 with blank cells" {
     const alloc = testing.allocator;
+    const io = testing.io;
     const cell_width = 36;
     const cell_height = 80;
 
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 100, .rows = 100 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 100, .rows = 100 });
     defer t.deinit(alloc);
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
 
     const image: Image = .{ .id = 1, .width = 500, .height = 306 };
-    try s.addImage(alloc, image);
-    try s.addPlacement(alloc, 1, 0, .{
+    try s.addImage(io, alloc, image);
+    try s.addPlacement(io, alloc, 1, 0, .{
         .location = .{ .virtual = {} },
         .columns = 2,
         .rows = 2,
@@ -1307,17 +1320,18 @@ test "unicode render placement: dog 2x2 with blank cells" {
 // printf "\033_Ga=p,i=1,U=1,q=2,c=1,r=1\033\\"
 test "unicode render placement: dog 1x1" {
     const alloc = testing.allocator;
+    const io = testing.io;
     const cell_width = 36;
     const cell_height = 80;
 
-    var t = try terminal.Terminal.init(alloc, .{ .cols = 100, .rows = 100 });
+    var t = try terminal.Terminal.init(io, alloc, .{ .cols = 100, .rows = 100 });
     defer t.deinit(alloc);
     var s: ImageStorage = .{};
     defer s.deinit(alloc, t.screens.active);
 
     const image: Image = .{ .id = 1, .width = 500, .height = 306 };
-    try s.addImage(alloc, image);
-    try s.addPlacement(alloc, 1, 0, .{
+    try s.addImage(io, alloc, image);
+    try s.addPlacement(io, alloc, 1, 0, .{
         .location = .{ .virtual = {} },
         .columns = 1,
         .rows = 1,
diff --git a/src/terminal/modes.zig b/src/terminal/modes.zig
index c92f97b08..da80e4d6b 100644
--- a/src/terminal/modes.zig
+++ b/src/terminal/modes.zig
@@ -101,45 +101,31 @@ pub const ModeState = struct {
 /// be used directly but rather through the ModeState struct.
 pub const ModePacked = packed_struct: {
     const StructField = std.builtin.Type.StructField;
-    var fields: [entries.len]StructField = undefined;
-    for (entries, 0..) |entry, i| {
-        fields[i] = .{
-            .name = entry.name,
-            .type = bool,
-            .default_value_ptr = &entry.default,
-            .is_comptime = false,
-            .alignment = 0,
-        };
+    var names: [entries.len][]const u8 = undefined;
+    var types = [_]type{bool} ** entries.len;
+    var attrs: [entries.len]StructField.Attributes = undefined;
+
+    for (entries, &names, &attrs) |entry, *name, *attr| {
+        name.* = entry.name;
+        attr.* = .{ .default_value_ptr = &entry.default };
     }
 
-    break :packed_struct @Type(.{ .@"struct" = .{
-        .layout = .@"packed",
-        .fields = &fields,
-        .decls = &.{},
-        .is_tuple = false,
-    } });
+    break :packed_struct @Struct(.@"packed", null, &names, &types, &attrs);
 };
 
 /// An enum(u16) of the available modes. See entries for available values.
 pub const Mode = mode_enum: {
-    const EnumField = std.builtin.Type.EnumField;
-    var fields: [entries.len]EnumField = undefined;
-    for (entries, 0..) |entry, i| {
-        fields[i] = .{
-            .name = entry.name,
-            .value = @as(ModeTag.Backing, @bitCast(ModeTag{
-                .value = entry.value,
-                .ansi = entry.ansi,
-            })),
-        };
+    var names: [entries.len][]const u8 = undefined;
+    var values: [entries.len]ModeTag.Backing = undefined;
+    for (entries, &names, &values) |entry, *name, *value| {
+        name.* = entry.name;
+        value.* = @bitCast(ModeTag{
+            .value = entry.value,
+            .ansi = entry.ansi,
+        });
     }
 
-    break :mode_enum @Type(.{ .@"enum" = .{
-        .tag_type = ModeTag.Backing,
-        .fields = &fields,
-        .decls = &.{},
-        .is_exhaustive = true,
-    } });
+    break :mode_enum @Enum(ModeTag.Backing, .exhaustive, &names, &values);
 };
 
 /// The tag type for our enum is a u16 but we use a packed struct
diff --git a/src/terminal/mouse.zig b/src/terminal/mouse.zig
index 2861ad1e0..2b0740a32 100644
--- a/src/terminal/mouse.zig
+++ b/src/terminal/mouse.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const build_options = @import("terminal_options");
 const lib = @import("lib.zig");
+const compat_testing = @import("../lib/compat/testing.zig");
 
 /// The event types that can be reported for mouse-related activities.
 /// These are all mutually exclusive (hence in a single enum).
@@ -164,5 +165,5 @@ test "cursor shape from string" {
 }
 
 test {
-    _ = std.testing.refAllDeclsRecursive(@This());
+    _ = compat_testing.refAllDeclsRecursive(@This());
 }
diff --git a/src/terminal/osc/parsers/color.zig b/src/terminal/osc/parsers/color.zig
index 547c98eaf..d8b89f411 100644
--- a/src/terminal/osc/parsers/color.zig
+++ b/src/terminal/osc/parsers/color.zig
@@ -6,6 +6,7 @@ const SpecialColor = @import("../../color.zig").Special;
 const RGB = @import("../../color.zig").RGB;
 const Parser = @import("../../osc.zig").Parser;
 const Command = @import("../../osc.zig").Command;
+const SegmentedList = @import("../../../datastruct/segmented_list.zig").SegmentedList;
 
 const log = std.log.scoped(.osc_color);
 
@@ -182,19 +183,19 @@ fn parseGetSetAnsiColor(
         // Parse the color.
         const target: Target = switch (op) {
             // OSC5 maps directly to the Special enum.
-            .osc_5 => .{ .special = std.meta.intToEnum(
+            .osc_5 => .{ .special = std.enums.fromInt(
                 SpecialColor,
                 std.math.cast(u3, color) orelse return result,
-            ) catch return result },
+            ) orelse return result },
 
             // OSC4 maps 0-255 to palette, 256-259 to special offset
             // by the palette count.
             .osc_4 => if (std.math.cast(u8, color)) |idx| .{
                 .palette = idx,
-            } else .{ .special = std.meta.intToEnum(
+            } else .{ .special = std.enums.fromInt(
                 SpecialColor,
                 std.math.cast(u3, color - 256) orelse return result,
-            ) catch return result },
+            ) orelse return result },
 
             else => comptime unreachable,
         };
@@ -255,19 +256,19 @@ fn parseResetAnsiColor(
         // Parse the color.
         const target: Target = switch (op) {
             // OSC105 maps directly to the Special enum.
-            .osc_105 => .{ .special = std.meta.intToEnum(
+            .osc_105 => .{ .special = std.enums.fromInt(
                 SpecialColor,
                 std.math.cast(u3, color) orelse continue,
-            ) catch continue },
+            ) orelse continue },
 
             // OSC104 maps 0-255 to palette, 256-259 to special offset
             // by the palette count.
             .osc_104 => if (std.math.cast(u8, color)) |idx| .{
                 .palette = idx,
-            } else .{ .special = std.meta.intToEnum(
+            } else .{ .special = std.enums.fromInt(
                 SpecialColor,
                 std.math.cast(u3, color - 256) orelse continue,
-            ) catch continue },
+            ) orelse continue },
 
             else => comptime unreachable,
         };
@@ -329,7 +330,7 @@ fn parseResetDynamicColor(
 /// The exact prealloc value is chosen arbitrarily assuming most
 /// color ops have very few. If we can get empirical data on more
 /// typical values we can switch to that.
-pub const List = std.SegmentedList(
+pub const List = SegmentedList(
     Request,
     2,
 );
@@ -450,7 +451,7 @@ test "OSC 4:" {
 
     // Test every special color
     for (0..@typeInfo(SpecialColor).@"enum".fields.len) |i| {
-        const special = try std.meta.intToEnum(SpecialColor, i);
+        const special = std.enums.fromInt(SpecialColor, i) orelse return error.InvalidEnumValue;
 
         // Simple color set
         // printf '\e]4;256;red\\'
@@ -482,7 +483,7 @@ test "OSC 5:" {
 
     // Test every special color
     for (0..@typeInfo(SpecialColor).@"enum".fields.len) |i| {
-        const special = try std.meta.intToEnum(SpecialColor, i);
+        const special = std.enums.fromInt(SpecialColor, i) orelse return error.InvalidEnumValue;
 
         // Simple color set
         // printf '\e]4;256;red\\'
@@ -592,7 +593,7 @@ test "OSC 104:" {
 
     // Test every special color
     for (0..@typeInfo(SpecialColor).@"enum".fields.len) |i| {
-        const special = try std.meta.intToEnum(SpecialColor, i);
+        const special = std.enums.fromInt(SpecialColor, i) orelse return error.InvalidEnumValue;
 
         // Simple color set
         // printf '\e]104;256\\'
diff --git a/src/terminal/page.zig b/src/terminal/page.zig
index ca6d9854c..dae019c1f 100644
--- a/src/terminal/page.zig
+++ b/src/terminal/page.zig
@@ -6,7 +6,7 @@ const ArenaAllocator = std.heap.ArenaAllocator;
 const assert = @import("../quirks.zig").inlineAssert;
 const testing = std.testing;
 const posix = std.posix;
-const windows = std.os.windows;
+const windows = @import("../os/windows.zig");
 const fastmem = @import("../fastmem.zig");
 const color = @import("color.zig");
 const hyperlink = @import("hyperlink.zig");
@@ -43,7 +43,7 @@ const AllocPosix = struct {
         return try posix.mmap(
             null,
             n,
-            posix.PROT.READ | posix.PROT.WRITE,
+            .{ .READ = true, .WRITE = true },
             .{ .TYPE = .PRIVATE, .ANONYMOUS = true },
             -1,
             0,
@@ -59,12 +59,12 @@ const AllocPosix = struct {
 /// MEM_COMMIT | MEM_RESERVE which guarantees zeroed pages.
 const AllocWindows = struct {
     pub fn alloc(n: usize) error{OutOfMemory}![]align(std.heap.page_size_min) u8 {
-        const addr = windows.VirtualAlloc(
+        const addr = windows.exp.kernel32.VirtualAlloc(
             null,
             n,
             windows.MEM_COMMIT | windows.MEM_RESERVE,
             windows.PAGE_READWRITE,
-        ) catch return error.OutOfMemory;
+        ) orelse return error.OutOfMemory;
 
         return @as(
             [*]align(std.heap.page_size_min) u8,
@@ -73,7 +73,7 @@ const AllocWindows = struct {
     }
 
     pub fn free(mem: []align(std.heap.page_size_min) u8) void {
-        windows.VirtualFree(
+        _ = windows.exp.kernel32.VirtualFree(
             @ptrCast(@alignCast(mem.ptr)),
             0,
             windows.MEM_RELEASE,
@@ -358,11 +358,11 @@ pub const Page = struct {
         }
     }
 
-    /// A helper that can be used to assert the integrity of the page
-    /// when runtime safety is enabled. This is a no-op when runtime
-    /// safety is disabled. This uses the libc allocator.
+    /// A helper that can be used to assert the integrity of the page when
+    /// runtime safety is enabled. This is a no-op when runtime safety is
+    /// disabled or the target is freestanding. This uses the libc allocator.
     pub inline fn assertIntegrity(self: *const Page) void {
-        if (comptime build_options.slow_runtime_safety) {
+        if (comptime build_options.slow_runtime_safety and builtin.os.tag != .freestanding) {
             var debug_allocator: std.heap.DebugAllocator(.{}) = .init;
             defer _ = debug_allocator.deinit();
             const alloc = debug_allocator.allocator();
@@ -2048,12 +2048,18 @@ pub const Cell = packed struct(u64) {
         /// The codepoint that this cell contains. If `grapheme` is false,
         /// then this is the only codepoint in the cell. If `grapheme` is
         /// true, then this is the first codepoint in the grapheme cluster.
-        codepoint: u21,
+        codepoint: packed struct(u24) {
+            data: u21,
+            _pad: u3 = 0,
+        },
 
         /// The content is an empty cell with a background color.
-        color_palette: u8,
+        color_palette: packed struct(u24) {
+            data: u8,
+            _pad: u16 = 0,
+        },
         color_rgb: RGB,
-    } = .{ .codepoint = 0 },
+    } = .{ .codepoint = .{ .data = 0 } },
 
     /// The style ID to use for this cell within the style map. Zero
     /// is always the default style so no lookup is required.
@@ -2150,7 +2156,7 @@ pub const Cell = packed struct(u64) {
         // memory in the packed union. Valgrind verifies this.
         var cell: Cell = @bitCast(@as(u64, 0));
         cell.content_tag = .codepoint;
-        cell.content = .{ .codepoint = cp };
+        cell.content = .{ .codepoint = .{ .data = cp } };
         return cell;
     }
 
@@ -2168,7 +2174,7 @@ pub const Cell = packed struct(u64) {
         return switch (self.content_tag) {
             .codepoint,
             .codepoint_grapheme,
-            => self.content.codepoint != 0,
+            => self.content.codepoint.data != 0,
 
             .bg_color_palette,
             .bg_color_rgb,
@@ -2180,7 +2186,7 @@ pub const Cell = packed struct(u64) {
         return switch (self.content_tag) {
             .codepoint,
             .codepoint_grapheme,
-            => self.content.codepoint,
+            => self.content.codepoint.data,
 
             .bg_color_palette,
             .bg_color_rgb,
@@ -2668,14 +2674,16 @@ test "Page read and write cells" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{
+                .codepoint = .{ .data = @intCast(y) },
+            },
         };
     }
 
     // Read it again
     for (0..page.capacity.rows) |y| {
         const rac = page.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 }
 
@@ -2769,7 +2777,7 @@ test "Page clone" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -2781,7 +2789,7 @@ test "Page clone" {
     // Read it again
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 
     // Write again
@@ -2789,20 +2797,20 @@ test "Page clone" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 0 },
+            .content = .{ .codepoint = .{ .data = 0 } },
         };
     }
 
     // Read it again, should be unchanged
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 
     // Read the original
     for (0..page.capacity.rows) |y| {
         const rac = page.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
     }
 }
 
@@ -2852,7 +2860,7 @@ test "Page clone styles" {
             rac.row.styled = true;
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x + 1) },
+                .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
                 .style_id = id,
             };
             page.styles.use(page.memory, id);
@@ -2897,7 +2905,7 @@ test "Page cloneFrom" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -2913,7 +2921,7 @@ test "Page cloneFrom" {
     // Read it again
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 
     // Write again
@@ -2921,20 +2929,20 @@ test "Page cloneFrom" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 0 },
+            .content = .{ .codepoint = .{ .data = 0 } },
         };
     }
 
     // Read it again, should be unchanged
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 
     // Read the original
     for (0..page.capacity.rows) |y| {
         const rac = page.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
     }
 }
 
@@ -2951,7 +2959,7 @@ test "Page cloneFrom shrink columns" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -2968,7 +2976,7 @@ test "Page cloneFrom shrink columns" {
     // Read it again
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
 }
 
@@ -2985,7 +2993,7 @@ test "Page cloneFrom partial" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y) },
+            .content = .{ .codepoint = .{ .data = @intCast(y) } },
         };
     }
 
@@ -3001,11 +3009,11 @@ test "Page cloneFrom partial" {
     // Read it again
     for (0..5) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y)), rac.cell.content.codepoint.data);
     }
     for (5..page2.size.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
     }
 }
 
@@ -3032,7 +3040,7 @@ test "Page cloneFrom hyperlinks exact capacity" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 42 },
+                .content = .{ .codepoint = .{ .data = 42 } },
             };
             try page.setHyperlink(rac.row, rac.cell, hyperlink_id);
             page.hyperlink_set.use(page.memory, hyperlink_id);
@@ -3066,7 +3074,7 @@ test "Page cloneFrom graphemes" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(y + 1) } },
         };
         try page.appendGrapheme(rac.row, rac.cell, 0x0A);
     }
@@ -3083,7 +3091,7 @@ test "Page cloneFrom graphemes" {
     // Read it again
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y + 1)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y + 1)), rac.cell.content.codepoint.data);
         try testing.expect(rac.row.grapheme);
         try testing.expect(rac.cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{0x0A}, page2.lookupGrapheme(rac.cell).?);
@@ -3096,14 +3104,14 @@ test "Page cloneFrom graphemes" {
         page.updateRowGraphemeFlag(rac.row);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = 0 },
+            .content = .{ .codepoint = .{ .data = 0 } },
         };
     }
 
     // Read it again, should be unchanged
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y + 1)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y + 1)), rac.cell.content.codepoint.data);
         try testing.expect(rac.row.grapheme);
         try testing.expect(rac.cell.hasGrapheme());
         try testing.expectEqualSlices(u21, &.{0x0A}, page2.lookupGrapheme(rac.cell).?);
@@ -3112,7 +3120,7 @@ test "Page cloneFrom graphemes" {
     // Read the original
     for (0..page.capacity.rows) |y| {
         const rac = page.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, 0), rac.cell.content.codepoint.data);
     }
 }
 
@@ -3127,7 +3135,7 @@ test "Page cloneFrom frees dst graphemes" {
         const rac = page.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(y + 1) } },
         };
     }
 
@@ -3142,7 +3150,7 @@ test "Page cloneFrom frees dst graphemes" {
         const rac = page2.getRowAndCell(1, y);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(y + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(y + 1) } },
         };
         try page2.appendGrapheme(rac.row, rac.cell, 0x0A);
     }
@@ -3153,7 +3161,7 @@ test "Page cloneFrom frees dst graphemes" {
     // Read it again
     for (0..page2.capacity.rows) |y| {
         const rac = page2.getRowAndCell(1, y);
-        try testing.expectEqual(@as(u21, @intCast(y + 1)), rac.cell.content.codepoint);
+        try testing.expectEqual(@as(u21, @intCast(y + 1)), rac.cell.content.codepoint.data);
         try testing.expect(!rac.row.grapheme);
         try testing.expect(!rac.cell.hasGrapheme());
     }
@@ -3175,7 +3183,7 @@ test "Page cloneRowFrom partial" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x + 1) },
+                .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
             };
         }
     }
@@ -3201,7 +3209,7 @@ test "Page cloneRowFrom partial" {
         for (0..page2.size.cols) |x| {
             const expected: u21 = if (x >= 2 and x < 8) @intCast(x + 1) else 0;
             const rac = page2.getRowAndCell(x, y);
-            try testing.expectEqual(expected, rac.cell.content.codepoint);
+            try testing.expectEqual(expected, rac.cell.content.codepoint.data);
         }
     }
 }
@@ -3221,7 +3229,7 @@ test "Page cloneRowFrom partial grapheme in non-copied source region" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x + 1) },
+                .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
             };
         }
         {
@@ -3256,7 +3264,7 @@ test "Page cloneRowFrom partial grapheme in non-copied source region" {
         for (0..page2.size.cols) |x| {
             const expected: u21 = if (x >= 2 and x < 8) @intCast(x + 1) else 0;
             const rac = page2.getRowAndCell(x, y);
-            try testing.expectEqual(expected, rac.cell.content.codepoint);
+            try testing.expectEqual(expected, rac.cell.content.codepoint.data);
             try testing.expect(!rac.cell.hasGrapheme());
         }
         {
@@ -3282,7 +3290,7 @@ test "Page cloneRowFrom partial grapheme in non-copied dest region" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x + 1) },
+                .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
             };
         }
     }
@@ -3301,7 +3309,7 @@ test "Page cloneRowFrom partial grapheme in non-copied dest region" {
             const rac = page2.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = 0xBB },
+                .content = .{ .codepoint = .{ .data = 0xBB } },
             };
         }
         {
@@ -3327,7 +3335,7 @@ test "Page cloneRowFrom partial grapheme in non-copied dest region" {
         for (0..page2.size.cols) |x| {
             const expected: u21 = if (x >= 2 and x < 8) @intCast(x + 1) else 0xBB;
             const rac = page2.getRowAndCell(x, y);
-            try testing.expectEqual(expected, rac.cell.content.codepoint);
+            try testing.expectEqual(expected, rac.cell.content.codepoint.data);
         }
         {
             const rac = page2.getRowAndCell(9, y);
@@ -3355,7 +3363,7 @@ test "Page cloneRowFrom partial hyperlink in same page copy" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x + 1) },
+                .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
             };
         }
 
@@ -3382,7 +3390,7 @@ test "Page cloneRowFrom partial hyperlink in same page copy" {
         for (0..page.size.cols) |x| {
             const expected: u21 = if (x >= 2 and x < 8) @intCast(x + 1) else 0;
             const rac = page.getRowAndCell(x, y);
-            try testing.expectEqual(expected, rac.cell.content.codepoint);
+            try testing.expectEqual(expected, rac.cell.content.codepoint.data);
         }
         {
             const rac = page.getRowAndCell(7, y);
@@ -3411,7 +3419,7 @@ test "Page cloneRowFrom partial hyperlink in same page omit" {
             const rac = page.getRowAndCell(x, y);
             rac.cell.* = .{
                 .content_tag = .codepoint,
-                .content = .{ .codepoint = @intCast(x + 1) },
+                .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
             };
         }
 
@@ -3438,7 +3446,7 @@ test "Page cloneRowFrom partial hyperlink in same page omit" {
         for (0..page.size.cols) |x| {
             const expected: u21 = if (x >= 2 and x < 6) @intCast(x + 1) else 0;
             const rac = page.getRowAndCell(x, y);
-            try testing.expectEqual(expected, rac.cell.content.codepoint);
+            try testing.expectEqual(expected, rac.cell.content.codepoint.data);
         }
         {
             const rac = page.getRowAndCell(7, y);
@@ -3462,7 +3470,7 @@ test "Page moveCells text-only" {
         const rac = page.getRowAndCell(x, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(x + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
         };
     }
 
@@ -3475,7 +3483,7 @@ test "Page moveCells text-only" {
         const rac = page.getRowAndCell(x, 1);
         try testing.expectEqual(
             @as(u21, @intCast(x + 1)),
-            rac.cell.content.codepoint,
+            rac.cell.content.codepoint.data,
         );
     }
 
@@ -3484,7 +3492,7 @@ test "Page moveCells text-only" {
         const rac = page.getRowAndCell(x, 0);
         try testing.expectEqual(
             @as(u21, 0),
-            rac.cell.content.codepoint,
+            rac.cell.content.codepoint.data,
         );
     }
 }
@@ -3502,7 +3510,7 @@ test "Page moveCells graphemes" {
         const rac = page.getRowAndCell(x, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(x + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
         };
         try page.appendGrapheme(rac.row, rac.cell, 0x0A);
     }
@@ -3518,7 +3526,7 @@ test "Page moveCells graphemes" {
         const rac = page.getRowAndCell(x, 1);
         try testing.expectEqual(
             @as(u21, @intCast(x + 1)),
-            rac.cell.content.codepoint,
+            rac.cell.content.codepoint.data,
         );
         try testing.expectEqualSlices(
             u21,
@@ -3532,7 +3540,7 @@ test "Page moveCells graphemes" {
         const rac = page.getRowAndCell(x, 0);
         try testing.expectEqual(
             @as(u21, 0),
-            rac.cell.content.codepoint,
+            rac.cell.content.codepoint.data,
         );
     }
 }
@@ -3554,7 +3562,7 @@ test "Page verifyIntegrity graphemes good" {
         const rac = page.getRowAndCell(x, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(x + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
         };
         try page.appendGrapheme(rac.row, rac.cell, 0x0A);
     }
@@ -3579,7 +3587,7 @@ test "Page verifyIntegrity grapheme row not marked" {
         const rac = page.getRowAndCell(x, 0);
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(x + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
         };
         try page.appendGrapheme(rac.row, rac.cell, 0x0A);
     }
@@ -3616,7 +3624,7 @@ test "Page verifyIntegrity styles good" {
         rac.row.styled = true;
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(x + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
             .style_id = id,
         };
         page.styles.use(page.memory, id);
@@ -3652,7 +3660,7 @@ test "Page verifyIntegrity styles ref count mismatch" {
         rac.row.styled = true;
         rac.cell.* = .{
             .content_tag = .codepoint,
-            .content = .{ .codepoint = @intCast(x + 1) },
+            .content = .{ .codepoint = .{ .data = @intCast(x + 1) } },
             .style_id = id,
         };
         page.styles.use(page.memory, id);
diff --git a/src/terminal/render.zig b/src/terminal/render.zig
index 04f0c9679..c70e69627 100644
--- a/src/terminal/render.zig
+++ b/src/terminal/render.zig
@@ -1180,7 +1180,7 @@ const RowBuilder = struct {
                             .b = page_cell.content.color_rgb.b,
                         } } },
                         .bg_color_palette => .{ .bg_color = .{
-                            .palette = page_cell.content.color_palette,
+                            .palette = page_cell.content.color_palette.data,
                         } },
                         else => unreachable,
                     };
@@ -1216,8 +1216,9 @@ const RowBuilder = struct {
 test "styled" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
     });
@@ -1234,8 +1235,9 @@ test "styled" {
 test "basic text" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -1270,8 +1272,9 @@ test "basic text" {
 test "styled text" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -1415,12 +1418,13 @@ fn testCompareStates(
 test "incremental updates match full rebuild" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     // Deterministic so failures are reproducible.
     var prng = std.Random.DefaultPrng.init(0xB0BA_CAFE);
     const rand = prng.random();
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 20,
         .rows = 8,
         .max_scrollback = 500,
@@ -1551,8 +1555,9 @@ test "incremental updates match full rebuild" {
 test "begin and end update" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -1599,8 +1604,9 @@ test "begin and end update" {
 test "bg color cells" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -1641,8 +1647,9 @@ test "bg color cells" {
 test "grapheme" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -1688,8 +1695,9 @@ test "grapheme" {
 test "cursor state in viewport" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 5,
     });
@@ -1730,8 +1738,9 @@ test "cursor state in viewport" {
 test "cursor state out of viewport" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 2,
     });
@@ -1764,8 +1773,9 @@ test "cursor state out of viewport" {
 test "dirty state" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 5,
     });
@@ -1813,8 +1823,9 @@ test "dirty state" {
 test "colors" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 5,
     });
@@ -1850,8 +1861,9 @@ test "colors" {
 test "selection single line" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t: Terminal = try .init(alloc, .{
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -1885,8 +1897,9 @@ test "selection single line" {
 test "selection multiple lines" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t: Terminal = try .init(alloc, .{
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -1921,8 +1934,9 @@ test "selection multiple lines" {
 test "linkCells" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 5,
     });
@@ -1957,8 +1971,9 @@ test "linkCells" {
 test "string" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 5,
         .rows = 2,
     });
@@ -1987,11 +2002,12 @@ test "string" {
 test "linkCells with scrollback spanning pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     const viewport_rows: size.CellCountInt = 10;
     const tail_rows: size.CellCountInt = 5;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = page.std_capacity.cols,
         .rows = viewport_rows,
         .max_scrollback = 10_000,
@@ -2029,8 +2045,9 @@ test "linkCells with scrollback spanning pages" {
 test "linkCells with invalid viewport point" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 5,
     });
@@ -2067,8 +2084,9 @@ test "linkCells with invalid viewport point" {
 test "flattened highlights require matching page serial" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
@@ -2134,8 +2152,9 @@ test "flattened highlights require matching page serial" {
 test "dirty row resets highlights" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var t = try Terminal.init(alloc, .{
+    var t = try Terminal.init(io, alloc, .{
         .cols = 10,
         .rows = 3,
     });
diff --git a/src/terminal/search/Thread.zig b/src/terminal/search/Thread.zig
index d7f0d5625..ecc727399 100644
--- a/src/terminal/search/Thread.zig
+++ b/src/terminal/search/Thread.zig
@@ -13,8 +13,9 @@ const builtin = @import("builtin");
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
-const Mutex = std.Thread.Mutex;
-const xev = @import("../../global.zig").xev;
+const Mutex = std.Io.Mutex;
+const global = @import("../../global.zig");
+const xev = global.xev;
 const internal_os = @import("../../os/main.zig");
 const BlockingQueue = @import("../../datastruct/main.zig").BlockingQueue;
 const MessageData = @import("../../datastruct/main.zig").MessageData;
@@ -122,8 +123,8 @@ pub fn deinit(self: *Thread) void {
     self.mailbox.destroy(self.alloc);
 
     if (self.search) |*s| {
-        self.opts.mutex.lock();
-        defer self.opts.mutex.unlock();
+        self.opts.mutex.lockUncancelable(global.io());
+        defer self.opts.mutex.unlock(global.io());
         s.deinit(self.opts.terminal);
     }
 }
@@ -182,7 +183,7 @@ fn threadMain_(self: *Thread) !void {
     while (true) {
         // If our loop is canceled then we drain our messages and quit.
         if (self.loop.stopped()) {
-            while (self.mailbox.pop()) |message| {
+            while (self.mailbox.pop(global.io())) |message| {
                 log.debug("mailbox message ignored during shutdown={}", .{message});
             }
 
@@ -225,8 +226,8 @@ fn threadMain_(self: *Thread) !void {
 
             // All searches are blocked. Let's grab the lock and feed data.
             .blocked => {
-                self.opts.mutex.lock();
-                defer self.opts.mutex.unlock();
+                self.opts.mutex.lockUncancelable(global.io());
+                defer self.opts.mutex.unlock(global.io());
                 s.feed(self.alloc, self.opts.terminal);
             },
         }
@@ -242,7 +243,7 @@ fn threadMain_(self: *Thread) !void {
 
 /// Drain the mailbox.
 fn drainMailbox(self: *Thread) !void {
-    while (self.mailbox.pop()) |message| {
+    while (self.mailbox.pop(global.io())) |message| {
         log.debug("mailbox message={}", .{message});
         switch (message) {
             .change_needle => |v| {
@@ -257,8 +258,8 @@ fn drainMailbox(self: *Thread) !void {
 fn select(self: *Thread, sel: ScreenSearch.Select) !void {
     const s = if (self.search) |*s| s else return;
 
-    self.opts.mutex.lock();
-    defer self.opts.mutex.unlock();
+    self.opts.mutex.lockUncancelable(global.io());
+    defer self.opts.mutex.unlock(global.io());
 
     // A screen can be removed or replaced between refresh ticks. Reconcile
     // while holding the terminal lock before touching any ScreenSearch pins.
@@ -317,8 +318,8 @@ fn changeNeedle(self: *Thread, needle: []const u8) !void {
         if (std.ascii.eqlIgnoreCase(s.viewport.needle(), needle)) return;
 
         {
-            self.opts.mutex.lock();
-            defer self.opts.mutex.unlock();
+            self.opts.mutex.lockUncancelable(global.io());
+            defer self.opts.mutex.unlock(global.io());
             s.deinit(self.opts.terminal);
         }
         self.search = null;
@@ -347,8 +348,8 @@ fn changeNeedle(self: *Thread, needle: []const u8) !void {
     self.search = try .init(self.alloc, needle);
 
     // We need to grab the terminal lock and do an initial feed.
-    self.opts.mutex.lock();
-    defer self.opts.mutex.unlock();
+    self.opts.mutex.lockUncancelable(global.io());
+    defer self.opts.mutex.unlock(global.io());
     self.search.?.feed(self.alloc, self.opts.terminal);
 }
 
@@ -423,8 +424,8 @@ fn refreshCallback(
 
     // Run our feed if we have a search active.
     if (self.search) |*s| {
-        self.opts.mutex.lock();
-        defer self.opts.mutex.unlock();
+        self.opts.mutex.lockUncancelable(global.io());
+        defer self.opts.mutex.unlock(global.io());
         s.feed(self.alloc, self.opts.terminal);
     }
 
@@ -851,7 +852,7 @@ const Search = struct {
 
 const TestUserData = struct {
     const Self = @This();
-    reset: std.Thread.ResetEvent = .{},
+    reset: std.Io.Event = .unset,
     total: usize = 0,
     selected: ?Event.SelectedMatch = null,
     viewport: []FlattenedHighlight = &.{},
@@ -865,7 +866,7 @@ const TestUserData = struct {
         const ud: *Self = @ptrCast(@alignCast(userdata.?));
         switch (event) {
             .quit => {},
-            .complete => ud.reset.set(),
+            .complete => ud.reset.set(global.io()),
             .total_matches => |v| ud.total = v,
             .selected_match => |v| ud.selected = v,
             .viewport_matches => |v| {
@@ -886,8 +887,9 @@ const TestUserData = struct {
 
 test {
     const alloc = testing.allocator;
-    var mutex: std.Thread.Mutex = .{};
-    var t: Terminal = try .init(alloc, .{ .cols = 20, .rows = 2 });
+    const io = testing.io;
+    var mutex: std.Io.Mutex = .init;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 20, .rows = 2 });
     defer t.deinit(alloc);
 
     var stream = t.vtStream();
@@ -912,6 +914,7 @@ test {
 
     // Start our search
     _ = thread.mailbox.push(
+        io,
         .{ .change_needle = try .init(
             alloc,
             @as([]const u8, "world"),
@@ -921,7 +924,7 @@ test {
     try thread.wakeup.notify();
 
     // Wait for completion
-    try ud.reset.timedWait(100 * std.time.ns_per_ms);
+    try ud.reset.waitTimeout(testing.io, .{ .duration = .{ .clock = .awake, .raw = .fromMilliseconds(100) } });
 
     // Stop the thread
     try thread.stop.notify();
@@ -945,8 +948,9 @@ test {
 
 test "select after active screen removal" {
     const alloc = testing.allocator;
-    var mutex: std.Thread.Mutex = .{};
-    var t: Terminal = try .init(alloc, .{ .cols = 20, .rows = 2 });
+    const io = testing.io;
+    var mutex: std.Io.Mutex = .init;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 20, .rows = 2 });
     defer t.deinit(alloc);
 
     _ = try t.switchScreen(.alternate);
diff --git a/src/terminal/search/active.zig b/src/terminal/search/active.zig
index b99b23579..b37f46d2b 100644
--- a/src/terminal/search/active.zig
+++ b/src/terminal/search/active.zig
@@ -103,7 +103,8 @@ pub const ActiveSearch = struct {
 
 test "simple search" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -143,7 +144,8 @@ test "simple search" {
 
 test "clear screen and search" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
diff --git a/src/terminal/search/pagelist.zig b/src/terminal/search/pagelist.zig
index 98a24c187..f9fb3c9c1 100644
--- a/src/terminal/search/pagelist.zig
+++ b/src/terminal/search/pagelist.zig
@@ -147,7 +147,8 @@ pub const PageListSearch = struct {
 
 test "simple search" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -194,7 +195,8 @@ test "simple search" {
 
 test "feed multiple pages with matches" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -238,7 +240,8 @@ test "feed multiple pages with matches" {
 
 test "feed multiple pages no matches" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -277,7 +280,8 @@ test "feed multiple pages no matches" {
 
 test "feed iteratively through multiple matches" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 80, .rows = 24 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 80, .rows = 24 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -318,7 +322,8 @@ test "feed iteratively through multiple matches" {
 
 test "feed with match spanning page boundary" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 80, .rows = 24 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 80, .rows = 24 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -372,7 +377,8 @@ test "feed with match spanning page boundary" {
 
 test "compressed history match spanning page boundary remains compressed" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 80,
         .rows = 24,
         .max_scrollback = 10 * 1024 * 1024,
@@ -442,7 +448,8 @@ test "compressed history match spanning page boundary remains compressed" {
 
 test "feed with match spanning page boundary with newline" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 80, .rows = 24 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 80, .rows = 24 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
diff --git a/src/terminal/search/screen.zig b/src/terminal/search/screen.zig
index e0cd99110..fee53e007 100644
--- a/src/terminal/search/screen.zig
+++ b/src/terminal/search/screen.zig
@@ -928,7 +928,8 @@ pub const ScreenSearch = struct {
 
 test "simple search" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 2 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -972,7 +973,8 @@ test "simple search" {
 
 test "simple search with history" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1013,7 +1015,8 @@ test "simple search with history" {
 
 test "reload active with history change" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1099,7 +1102,8 @@ test "reload active with history change" {
 
 test "active change contents" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 5 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1139,7 +1143,8 @@ test "active change contents" {
 
 test "select next" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 2 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1198,7 +1203,8 @@ test "select next" {
 
 test "select after resize resets stale flattened results" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 3,
         .max_scrollback = std.math.maxInt(usize),
@@ -1232,7 +1238,8 @@ test "select after resize resets stale flattened results" {
 
 test "select in active changes contents completely" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 5 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 5 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1296,7 +1303,8 @@ test "select in active changes contents completely" {
 
 test "select into history" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1368,7 +1376,8 @@ test "select into history" {
 
 test "select prev" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 2 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1427,7 +1436,8 @@ test "select prev" {
 
 test "select prev then next" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 2 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1471,7 +1481,8 @@ test "select prev then next" {
 
 test "select prev with history" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1525,7 +1536,8 @@ test "select prev wraps when all matches are in history" {
     // has none, so active_len == 0), selecting prev from index 0 must wrap
     // to the last result without underflowing `active_len - 1`.
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1561,7 +1573,8 @@ test "select after all matches disappear drops the selection" {
     // reload/prune empties the results, the selection is dropped, so the next
     // select() hits the "no matches" guard instead of the wrap arithmetic.
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 2 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1588,7 +1601,8 @@ test "select after all matches disappear drops the selection" {
 
 test "select after partial history erase drops a pruned selection" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1620,7 +1634,8 @@ test "select after partial history erase drops a pruned selection" {
 
 test "select after history compaction ignores replaced results" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1654,7 +1669,8 @@ test "select after history compaction ignores replaced results" {
 
 test "select after partial history page erase ignores shifted results" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1687,7 +1703,8 @@ test "select after partial history page erase ignores shifted results" {
 
 test "reload defers pruning unselected history results" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1721,7 +1738,8 @@ test "reload defers pruning unselected history results" {
 
 test "reload after partial history page erase drops shifted selection first" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1759,7 +1777,8 @@ test "reload after partial history page erase drops shifted selection first" {
 
 test "select after history page split ignores moved results" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1792,7 +1811,8 @@ test "select after history page split ignores moved results" {
 
 test "screen search no scrollback has no history" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = 0,
@@ -1828,7 +1848,8 @@ test "reloadActive partial history cleanup on appendSlice error" {
     // This test verifies that when reloadActive fails at appendSlice (after
     // the loop), all FlattenedHighlight items are properly cleaned up.
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1875,7 +1896,8 @@ test "reloadActive partial history cleanup on loop append error" {
     // (after some items have been appended), all FlattenedHighlight items
     // are properly cleaned up.
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
@@ -1921,7 +1943,8 @@ test "select after clearing scrollback" {
     // Regression test for: https://github.com/ghostty-org/ghostty/issues/11957
     // After clearing scrollback (CSI 3J), selecting next/prev should not crash.
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{
         .cols = 10,
         .rows = 2,
         .max_scrollback = std.math.maxInt(usize),
diff --git a/src/terminal/search/sliding_window.zig b/src/terminal/search/sliding_window.zig
index 2f858ec85..e83a187ae 100644
--- a/src/terminal/search/sliding_window.zig
+++ b/src/terminal/search/sliding_window.zig
@@ -714,11 +714,12 @@ test "SlidingWindow empty on init" {
 test "SlidingWindow empty needle has no matches" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{
+    var s = try Screen.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
         .max_scrollback = 0,
@@ -733,11 +734,12 @@ test "SlidingWindow empty needle has no matches" {
 test "SlidingWindow single append" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "boo!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello. boo! hello. boo!");
 
@@ -778,11 +780,12 @@ test "SlidingWindow single append" {
 test "SlidingWindow single append case insensitive ASCII" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "Boo!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello. boo! hello. boo!");
 
@@ -823,11 +826,12 @@ test "SlidingWindow single append case insensitive ASCII" {
 test "SlidingWindow single append single char" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "b");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello. boo! hello. boo!");
 
@@ -868,11 +872,12 @@ test "SlidingWindow single append single char" {
 test "SlidingWindow single append no match" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "nope!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello. boo! hello. boo!");
 
@@ -892,11 +897,12 @@ test "SlidingWindow single append no match" {
 test "SlidingWindow two pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "boo!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -947,11 +953,12 @@ test "SlidingWindow two pages" {
 test "SlidingWindow two pages single char" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "b");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1002,11 +1009,12 @@ test "SlidingWindow two pages single char" {
 test "SlidingWindow two pages match across boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "hello, world");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1047,11 +1055,12 @@ test "SlidingWindow two pages match across boundary" {
 test "SlidingWindow two pages no match across boundary with newline" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "hello, world");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1080,11 +1089,12 @@ test "SlidingWindow two pages no match across boundary with newline" {
 test "SlidingWindow two pages no match across boundary with newline reverse" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "hello, world");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1110,11 +1120,12 @@ test "SlidingWindow two pages no match across boundary with newline reverse" {
 test "SlidingWindow two pages no match prunes first page" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "nope!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1145,8 +1156,9 @@ test "SlidingWindow two pages no match prunes first page" {
 test "SlidingWindow two pages no match keeps both pages" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1185,11 +1197,12 @@ test "SlidingWindow two pages no match keeps both pages" {
 test "SlidingWindow single append across circular buffer boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "abc");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("XXXXXXXXXXXXXXXXXXXboo!XXXXX");
 
@@ -1241,11 +1254,12 @@ test "SlidingWindow single append across circular buffer boundary" {
 test "SlidingWindow single append match on boundary" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "abcd");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("o!XXXXXXXXXXXXXXXXXXXbo");
 
@@ -1300,11 +1314,12 @@ test "SlidingWindow single append match on boundary" {
 test "SlidingWindow single append reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "boo!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello. boo! hello. boo!");
 
@@ -1345,11 +1360,12 @@ test "SlidingWindow single append reversed" {
 test "SlidingWindow single append no match reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "nope!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("hello. boo! hello. boo!");
 
@@ -1369,11 +1385,12 @@ test "SlidingWindow single append no match reversed" {
 test "SlidingWindow two pages reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "boo!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1424,11 +1441,12 @@ test "SlidingWindow two pages reversed" {
 test "SlidingWindow two pages match across boundary reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "hello, world");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1479,11 +1497,12 @@ test "SlidingWindow two pages match across boundary reversed" {
 test "SlidingWindow two pages no match prunes first page reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "nope!");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1514,8 +1533,9 @@ test "SlidingWindow two pages no match prunes first page reversed" {
 test "SlidingWindow two pages no match keeps both pages reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 1000 });
     defer s.deinit();
 
     // Fill up the first page. The final bytes in the first page
@@ -1554,11 +1574,12 @@ test "SlidingWindow two pages no match keeps both pages reversed" {
 test "SlidingWindow single append across circular buffer boundary reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "abc");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("XXXXXXXXXXXXXXXXXXXboo!XXXXX");
 
@@ -1611,11 +1632,12 @@ test "SlidingWindow single append across circular buffer boundary reversed" {
 test "SlidingWindow single append match on boundary reversed" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "abcd");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
+    var s = try Screen.init(io, alloc, .{ .cols = 80, .rows = 24, .max_scrollback = 0 });
     defer s.deinit();
     try s.testWriteString("o!XXXXXXXXXXXXXXXXXXXbo");
 
@@ -1671,11 +1693,12 @@ test "SlidingWindow single append match on boundary reversed" {
 test "SlidingWindow single append soft wrapped" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "boo!");
     defer w.deinit();
 
-    var t: Terminal = try .init(alloc, .{ .cols = 4, .rows = 5 });
+    var t: Terminal = try .init(io, alloc, .{ .cols = 4, .rows = 5 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1708,11 +1731,12 @@ test "SlidingWindow single append soft wrapped" {
 test "SlidingWindow single append reversed soft wrapped" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .reverse, "boo!");
     defer w.deinit();
 
-    var t: Terminal = try .init(alloc, .{ .cols = 4, .rows = 5 });
+    var t: Terminal = try .init(io, alloc, .{ .cols = 4, .rows = 5 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -1747,11 +1771,12 @@ test "SlidingWindow single append reversed soft wrapped" {
 test "SlidingWindow append whitespace only node" {
     const testing = std.testing;
     const alloc = testing.allocator;
+    const io = testing.io;
 
     var w: SlidingWindow = try .init(alloc, .forward, "x");
     defer w.deinit();
 
-    var s = try Screen.init(alloc, .{
+    var s = try Screen.init(io, alloc, .{
         .cols = 80,
         .rows = 24,
         .max_scrollback = 0,
diff --git a/src/terminal/search/viewport.zig b/src/terminal/search/viewport.zig
index 09d202bea..93e63b88b 100644
--- a/src/terminal/search/viewport.zig
+++ b/src/terminal/search/viewport.zig
@@ -228,7 +228,8 @@ pub const ViewportSearch = struct {
 
 test "simple search" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -271,7 +272,8 @@ test "simple search" {
 
 test "fingerprint detects node generation changes" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var search: ViewportSearch = try .init(alloc, "needle");
@@ -298,7 +300,8 @@ test "fingerprint detects node generation changes" {
 
 test "fingerprint only allocates on changes" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var failing = testing.FailingAllocator.init(alloc, .{});
@@ -320,7 +323,8 @@ test "fingerprint only allocates on changes" {
 
 test "clear screen and search" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -353,7 +357,8 @@ test "clear screen and search" {
 
 test "clear screen and search dirty tracking" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 10 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 10 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
@@ -400,7 +405,8 @@ test "clear screen and search dirty tracking" {
 
 test "history search, no active area" {
     const alloc = testing.allocator;
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 2 });
+    const io = testing.io;
+    var t: Terminal = try .init(io, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     var s = t.vtStream();
diff --git a/src/terminal/stream.zig b/src/terminal/stream.zig
index efb06ecdc..791d0c55d 100644
--- a/src/terminal/stream.zig
+++ b/src/terminal/stream.zig
@@ -579,8 +579,30 @@ pub fn Stream(comptime H: type) type {
                         continue;
                     }
 
+                    // Find the end of the printable run. This is an
+                    // early-exit search loop that LLVM won't
+                    // auto-vectorize, and printable runs dominate real
+                    // input, so scan several codepoints at a time
+                    // manually (same idiom as the printSliceFill run
+                    // scan).
                     var end = i + 1;
-                    while (end < cps.len and cps[end] > 0xF) end += 1;
+                    scan: {
+                        if (simd.lanes(u32)) |lanes| {
+                            const V = @Vector(lanes, u32);
+                            const threshold: V = @splat(0xF);
+                            while (end + lanes <= cps.len) {
+                                const v: V = cps[end..][0..lanes].*;
+                                const gt = v > threshold;
+                                if (!@reduce(.And, gt)) {
+                                    const bits: std.meta.Int(.unsigned, lanes) = @bitCast(gt);
+                                    end += @ctz(~bits);
+                                    break :scan;
+                                }
+                                end += lanes;
+                            }
+                        }
+                        while (end < cps.len and cps[end] > 0xF) end += 1;
+                    }
                     self.handler.vt(.print_slice, .{ .cps = cps[i..end] });
                     i = end;
                 }
@@ -1323,7 +1345,7 @@ pub fn Stream(comptime H: type) type {
 
                     const mode_: ?csi.EraseDisplay = switch (input.params.len) {
                         0 => .below,
-                        1 => std.meta.intToEnum(csi.EraseDisplay, input.params[0]) catch null,
+                        1 => std.enums.fromInt(csi.EraseDisplay, input.params[0]),
                         else => null,
                     };
 
@@ -1652,7 +1674,7 @@ pub fn Stream(comptime H: type) type {
                 'g' => switch (input.intermediates.len) {
                     0 => {
                         const mode: csi.TabClear = switch (input.params.len) {
-                            1 => std.meta.intToEnum(csi.TabClear, input.params[0]) catch {
+                            1 => std.enums.fromInt(csi.TabClear, input.params[0]) orelse {
                                 log.warn("invalid tab clear mode: {}", .{input.params[0]});
                                 return;
                             },
diff --git a/src/terminal/stream_terminal.zig b/src/terminal/stream_terminal.zig
index 1e4dc24be..bbbe5f83e 100644
--- a/src/terminal/stream_terminal.zig
+++ b/src/terminal/stream_terminal.zig
@@ -858,6 +858,7 @@ pub const Handler = struct {
     }
 
     fn apcEnd(self: *Handler) void {
+        const io = self.terminal.io();
         const alloc = self.terminal.gpa();
         var cmd = self.apc_handler.end() orelse return;
         defer cmd.deinit(alloc);
@@ -865,6 +866,7 @@ pub const Handler = struct {
         switch (cmd) {
             .kitty => |*kitty_cmd| if (comptime build_options.kitty_graphics) {
                 if (self.terminal.kittyGraphics(
+                    io,
                     alloc,
                     kitty_cmd,
                 )) |resp| resp: {
@@ -905,7 +907,7 @@ pub const Handler = struct {
 };
 
 test "resize clears synchronized output on unchanged cell dimensions" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -924,7 +926,7 @@ test "resize clears synchronized output on unchanged cell dimensions" {
 }
 
 test "resize reports mode 2048 geometry" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -966,7 +968,7 @@ test "resize suppresses mode 2048 reports" {
     };
     S.calls = 0;
 
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
     var handler: Handler = .init(&t);
     handler.effects.write_pty = &S.writePty;
@@ -988,6 +990,7 @@ test "resize suppresses mode 2048 reports" {
 
     // A read-only stream has no write effect and remains successful.
     var readonly_terminal: Terminal = try .init(
+        testing.io,
         testing.allocator,
         .{ .cols = 80, .rows = 24 },
     );
@@ -1009,7 +1012,7 @@ test "resize suppresses mode 2048 reports" {
 test "resize failure preserves terminal state and does not write" {
     var failing = testing.FailingAllocator.init(testing.allocator, .{});
     const alloc = failing.allocator();
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 1 });
+    var t: Terminal = try .init(testing.io, alloc, .{ .cols = 10, .rows = 1 });
     defer t.deinit(alloc);
 
     const S = struct {
@@ -1044,11 +1047,13 @@ test "resize failure preserves terminal state and does not write" {
 
 test "resize effects do not change canonical terminal state" {
     var authoritative: Terminal = try .init(
+        testing.io,
         testing.allocator,
         .{ .cols = 10, .rows = 5 },
     );
     defer authoritative.deinit(testing.allocator);
     var readonly: Terminal = try .init(
+        testing.io,
         testing.allocator,
         .{ .cols = 10, .rows = 5 },
     );
@@ -1092,7 +1097,7 @@ test "resize effects do not change canonical terminal state" {
 }
 
 test "basic print" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1110,7 +1115,7 @@ test "basic print" {
 test "semantic failure is sticky while processing continues" {
     var failing = testing.FailingAllocator.init(testing.allocator, .{});
     const alloc = failing.allocator();
-    var t: Terminal = try .init(alloc, .{ .cols = 10, .rows = 2 });
+    var t: Terminal = try .init(testing.io, alloc, .{ .cols = 10, .rows = 2 });
     defer t.deinit(alloc);
 
     var s: Stream = .initAlloc(alloc, .init(&t));
@@ -1141,7 +1146,7 @@ test "semantic failure is sticky while processing continues" {
 }
 
 test "cursor movement" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1159,7 +1164,7 @@ test "cursor movement" {
 }
 
 test "erase operations" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 20, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 20, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1180,7 +1185,7 @@ test "erase operations" {
 }
 
 test "tabs" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1195,7 +1200,7 @@ test "tabs" {
 }
 
 test "modes" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1210,7 +1215,7 @@ test "modes" {
 }
 
 test "scrolling regions" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1225,7 +1230,7 @@ test "scrolling regions" {
 }
 
 test "charsets" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1241,7 +1246,7 @@ test "charsets" {
 }
 
 test "alt screen" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 5 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 5 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1268,7 +1273,7 @@ test "alt screen" {
 }
 
 test "cursor save and restore" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1294,7 +1299,7 @@ test "cursor save and restore" {
 }
 
 test "attributes" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1310,7 +1315,7 @@ test "attributes" {
 }
 
 test "DECALN screen alignment" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 3 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 3 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1330,7 +1335,7 @@ test "DECALN screen alignment" {
 }
 
 test "full reset" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1357,7 +1362,7 @@ test "full reset" {
 }
 
 test "glyph protocol APC with write_pty callback" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -1385,7 +1390,7 @@ test "glyph protocol APC with write_pty callback" {
 }
 
 test "ignores query actions" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1413,7 +1418,7 @@ test "ignores query actions" {
 }
 
 test "OSC 4 set and reset palette" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1436,7 +1441,7 @@ test "OSC 4 set and reset palette" {
 }
 
 test "OSC 104 reset all palette colors" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1461,7 +1466,7 @@ test "OSC 104 reset all palette colors" {
 }
 
 test "OSC 10 set and reset foreground color" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1483,7 +1488,7 @@ test "OSC 10 set and reset foreground color" {
 }
 
 test "OSC 11 set and reset background color" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1502,7 +1507,7 @@ test "OSC 11 set and reset background color" {
 }
 
 test "OSC 12 set and reset cursor color" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1521,7 +1526,7 @@ test "OSC 12 set and reset cursor color" {
 }
 
 test "OSC color query responses" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -1578,7 +1583,7 @@ test "OSC color query responses" {
 }
 
 test "kitty color protocol set palette" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1594,7 +1599,7 @@ test "kitty color protocol set palette" {
 }
 
 test "kitty color protocol reset palette" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1611,7 +1616,7 @@ test "kitty color protocol reset palette" {
 }
 
 test "kitty color protocol set foreground" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1626,7 +1631,7 @@ test "kitty color protocol set foreground" {
 }
 
 test "kitty color protocol set background" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1641,7 +1646,7 @@ test "kitty color protocol set background" {
 }
 
 test "kitty color protocol set cursor" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1656,7 +1661,7 @@ test "kitty color protocol set cursor" {
 }
 
 test "kitty color protocol reset foreground" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1672,7 +1677,7 @@ test "kitty color protocol reset foreground" {
 }
 
 test "kitty color protocol query responses" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -1712,7 +1717,7 @@ test "kitty color protocol query responses" {
 }
 
 test "palette dirty flag set on color change" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1737,7 +1742,7 @@ test "palette dirty flag set on color change" {
 }
 
 test "semantic prompt fresh line" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1750,7 +1755,7 @@ test "semantic prompt fresh line" {
 }
 
 test "semantic prompt fresh line new prompt" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1774,7 +1779,7 @@ test "semantic prompt fresh line new prompt" {
 }
 
 test "semantic prompt end of input, then start output" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1791,7 +1796,7 @@ test "semantic prompt end of input, then start output" {
 }
 
 test "semantic prompt prompt_start" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1808,7 +1813,7 @@ test "semantic prompt prompt_start" {
 }
 
 test "semantic prompt new_command" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1826,7 +1831,7 @@ test "semantic prompt new_command" {
 }
 
 test "semantic prompt new_command at column zero" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1840,7 +1845,7 @@ test "semantic prompt new_command at column zero" {
 }
 
 test "semantic prompt end_prompt_start_input_terminate_eol clears on linefeed" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -1856,7 +1861,7 @@ test "semantic prompt end_prompt_start_input_terminate_eol clears on linefeed" {
 }
 
 test "bell effect callback" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     // Test bell with null callback (default readonly effects) doesn't crash
@@ -1900,7 +1905,7 @@ test "bell effect callback" {
 }
 
 test "clipboard_write effect callback" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     // A null callback (the default readonly effects) silently ignores writes.
@@ -2018,7 +2023,7 @@ test "clipboard_write effect callback" {
 }
 
 test "clipboard_write allocation failure is ignored" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2050,7 +2055,7 @@ test "clipboard_write allocation failure is ignored" {
 }
 
 test "request mode DECRQM with write_pty callback" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     // Without callback, DECRQM should not crash
@@ -2100,7 +2105,7 @@ test "request mode DECRQM with write_pty callback" {
 test "stream: CSI W with intermediate but no params" {
     // Regression test from AFL++ crash. CSI ? W without
     // parameters caused an out-of-bounds access on input.params[0].
-    var t: Terminal = try .init(testing.allocator, .{
+    var t: Terminal = try .init(testing.io, testing.allocator, .{
         .cols = 80,
         .rows = 24,
         .max_scrollback = 100,
@@ -2114,7 +2119,7 @@ test "stream: CSI W with intermediate but no params" {
 }
 
 test "window_title effect is called" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2138,7 +2143,7 @@ test "window_title effect is called" {
 }
 
 test "window_title effect not called without callback" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -2158,7 +2163,7 @@ test "window_title effect not called without callback" {
 }
 
 test "window_title effect with empty title" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2182,7 +2187,7 @@ test "window_title effect with empty title" {
 }
 
 test "kitty_keyboard_query" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2211,7 +2216,7 @@ test "kitty_keyboard_query" {
 }
 
 test "xtversion default" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2234,7 +2239,7 @@ test "xtversion default" {
 }
 
 test "xtversion with effect" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2260,7 +2265,7 @@ test "xtversion with effect" {
 }
 
 test "xtversion with empty string effect" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2287,7 +2292,7 @@ test "xtversion with empty string effect" {
 }
 
 test "size report csi_14_t with effect" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2315,7 +2320,7 @@ test "size report csi_14_t with effect" {
 }
 
 test "size report csi_16_t with effect" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2343,7 +2348,7 @@ test "size report csi_16_t with effect" {
 }
 
 test "size report csi_18_t with effect" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2371,7 +2376,7 @@ test "size report csi_18_t with effect" {
 }
 
 test "size report no effect callback" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2394,7 +2399,7 @@ test "size report no effect callback" {
 }
 
 test "size report csi_21_t title" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2421,7 +2426,7 @@ test "size report csi_21_t title" {
 }
 
 test "enquiry no effect" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2444,7 +2449,7 @@ test "enquiry no effect" {
 }
 
 test "enquiry with effect" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2471,7 +2476,7 @@ test "enquiry with effect" {
 }
 
 test "enquiry with empty response" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2498,7 +2503,7 @@ test "enquiry with empty response" {
 }
 
 test "device status: operating status" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2523,7 +2528,7 @@ test "device status: operating status" {
 }
 
 test "device status: cursor position" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2553,7 +2558,7 @@ test "device status: cursor position" {
 }
 
 test "device status: cursor position with origin mode" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2585,7 +2590,7 @@ test "device status: cursor position with origin mode" {
 }
 
 test "device status: color scheme dark" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2614,7 +2619,7 @@ test "device status: color scheme dark" {
 }
 
 test "device status: color scheme light" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2643,7 +2648,7 @@ test "device status: color scheme light" {
 }
 
 test "device status: color scheme without callback" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2668,7 +2673,7 @@ test "device status: color scheme without callback" {
 }
 
 test "device status: readonly ignores all" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -2687,7 +2692,7 @@ test "device status: readonly ignores all" {
 }
 
 test "device attributes: primary DA" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2715,7 +2720,7 @@ test "device attributes: primary DA" {
 }
 
 test "device attributes: secondary DA" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2743,7 +2748,7 @@ test "device attributes: secondary DA" {
 }
 
 test "device attributes: tertiary DA" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2771,7 +2776,7 @@ test "device attributes: tertiary DA" {
 }
 
 test "device attributes: readonly ignores" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     var s: Stream = .initAlloc(testing.allocator, .init(&t));
@@ -2790,7 +2795,7 @@ test "device attributes: readonly ignores" {
 }
 
 test "device attributes: custom response" {
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 80, .rows = 24 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 80, .rows = 24 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2832,7 +2837,7 @@ test "device attributes: custom response" {
 test "kitty graphics APC response" {
     if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
 
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     const S = struct {
@@ -2861,7 +2866,7 @@ test "kitty graphics APC response" {
 test "kitty graphics via APC" {
     if (comptime !build_options.kitty_graphics) return error.SkipZigTest;
 
-    var t: Terminal = try .init(testing.allocator, .{ .cols = 10, .rows = 10 });
+    var t: Terminal = try .init(testing.io, testing.allocator, .{ .cols = 10, .rows = 10 });
     defer t.deinit(testing.allocator);
 
     const handler: Handler = .init(&t);
diff --git a/src/terminal/style.zig b/src/terminal/style.zig
index 720789bb2..c7de43378 100644
--- a/src/terminal/style.zig
+++ b/src/terminal/style.zig
@@ -111,7 +111,7 @@ pub const Style = struct {
         palette: *const color.Palette,
     ) ?color.RGB {
         return switch (cell.content_tag) {
-            .bg_color_palette => palette[cell.content.color_palette],
+            .bg_color_palette => palette[cell.content.color_palette.data],
             .bg_color_rgb => rgb: {
                 const rgb = cell.content.color_rgb;
                 break :rgb .{ .r = rgb.r, .g = rgb.g, .b = rgb.b };
@@ -212,7 +212,7 @@ pub const Style = struct {
             .none => null,
             .palette => |idx| .{
                 .content_tag = .bg_color_palette,
-                .content = .{ .color_palette = idx },
+                .content = .{ .color_palette = .{ .data = idx } },
             },
             .rgb => |rgb| .{
                 .content_tag = .bg_color_rgb,
diff --git a/src/terminal/tmux/control.zig b/src/terminal/tmux/control.zig
index 3b94eb16b..b06560ddd 100644
--- a/src/terminal/tmux/control.zig
+++ b/src/terminal/tmux/control.zig
@@ -117,7 +117,7 @@ pub const Parser = struct {
                 const line = written[idx..];
 
                 if (parseBlockTerminator(line)) |terminator| {
-                    const output = std.mem.trimRight(
+                    const output = std.mem.trimEnd(
                         u8,
                         written[0..idx],
                         "\r\n",
diff --git a/src/terminal/tmux/output.zig b/src/terminal/tmux/output.zig
index 6b8073e44..9e21703b6 100644
--- a/src/terminal/tmux/output.zig
+++ b/src/terminal/tmux/output.zig
@@ -70,23 +70,17 @@ pub fn format(
 /// format variables. This can be used with `parseFormatStruct` to
 /// parse an output string into a format struct.
 pub fn FormatStruct(comptime vars: []const Variable) type {
-    var fields: [vars.len]std.builtin.Type.StructField = undefined;
-    for (vars, &fields) |variable, *field| {
-        field.* = .{
-            .name = @tagName(variable),
-            .type = variable.Type(),
-            .default_value_ptr = null,
-            .is_comptime = false,
-            .alignment = @alignOf(variable.Type()),
-        };
+    var names: [vars.len][]const u8 = undefined;
+    var types: [vars.len]type = undefined;
+    var attrs: [vars.len]std.builtin.Type.StructField.Attributes = undefined;
+
+    for (vars, &names, &types, &attrs) |variable, *name, *ty, *attr| {
+        name.* = @tagName(variable);
+        ty.* = variable.Type();
+        attr.* = .{ .@"align" = @alignOf(variable.Type()) };
     }
 
-    return @Type(.{ .@"struct" = .{
-        .layout = .auto,
-        .fields = &fields,
-        .decls = &.{},
-        .is_tuple = false,
-    } });
+    return @Struct(.auto, null, &names, &types, &attrs);
 }
 
 /// Possible variables in a tmux format string that we support.
diff --git a/src/terminal/tmux/viewer.zig b/src/terminal/tmux/viewer.zig
index 585c95403..5f0800893 100644
--- a/src/terminal/tmux/viewer.zig
+++ b/src/terminal/tmux/viewer.zig
@@ -156,6 +156,9 @@ const COMMAND_QUEUE_INITIAL = 8;
 /// session.
 ///
 pub const Viewer = struct {
+    /// I/O implementation used for all internal state.
+    io: std.Io,
+
     /// Allocator used for all internal state.
     alloc: Allocator,
 
@@ -265,12 +268,13 @@ pub const Viewer = struct {
     ///
     /// The given allocator is used for all internal state. You must
     /// call deinit when you're done with the viewer to free it.
-    pub fn init(alloc: Allocator) Allocator.Error!Viewer {
+    pub fn init(io: std.Io, alloc: Allocator) Allocator.Error!Viewer {
         // Create our initial command queue
         var command_queue: CommandQueue = try .init(alloc, COMMAND_QUEUE_INITIAL);
         errdefer command_queue.deinit(alloc);
 
         return .{
+            .io = io,
             .alloc = alloc,
             .state = .startup_block,
             // The default value here is meaningless. We don't get started
@@ -639,6 +643,7 @@ pub const Viewer = struct {
             panes.deinit(self.alloc);
         }
         for (windows) |window| try initLayout(
+            self.io,
             self.alloc,
             &self.panes,
             &panes,
@@ -723,7 +728,7 @@ pub const Viewer = struct {
         session_id: usize,
     ) (Allocator.Error || std.Io.Writer.Error)!void {
         // Build up a new viewer. Its the easiest way to reset ourselves.
-        var replacement: Viewer = try .init(self.alloc);
+        var replacement: Viewer = try .init(self.io, self.alloc);
         errdefer replacement.deinit();
 
         // Our actions must start out empty so we don't mix arenas
@@ -1115,6 +1120,7 @@ pub const Viewer = struct {
     }
 
     fn initLayout(
+        io: std.Io,
         gpa_alloc: Allocator,
         panes_old: *const PanesMap,
         panes_new: *PanesMap,
@@ -1125,6 +1131,7 @@ pub const Viewer = struct {
             .horizontal, .vertical => |layouts| {
                 for (layouts) |l| {
                     try initLayout(
+                        io,
                         gpa_alloc,
                         panes_old,
                         panes_new,
@@ -1149,7 +1156,7 @@ pub const Viewer = struct {
                 // TODO: We need to gracefully handle overflow of our
                 // max cols/width here. In practice we shouldn't hit this
                 // so we cast but its not safe.
-                var t: Terminal = try .init(gpa_alloc, .{
+                var t: Terminal = try .init(io, gpa_alloc, .{
                     .cols = @intCast(layout.width),
                     .rows = @intCast(layout.height),
                 });
@@ -1494,7 +1501,7 @@ fn testViewer(viewer: *Viewer, steps: []const TestStep) !void {
 }
 
 test "immediate exit" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -1514,7 +1521,7 @@ test "immediate exit" {
 }
 
 test "session changed resets state" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -1605,7 +1612,7 @@ test "session changed resets state" {
 }
 
 test "initial flow" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -1786,7 +1793,7 @@ test "initial flow" {
 }
 
 test "layout change" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -1857,7 +1864,7 @@ test "layout change" {
 }
 
 test "layout_change does not return command when queue not empty" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -1918,7 +1925,7 @@ test "layout_change does not return command when queue not empty" {
 }
 
 test "layout_change returns command when queue was empty" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -1985,7 +1992,7 @@ test "layout_change returns command when queue was empty" {
 }
 
 test "window_add queues list_windows when queue empty" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -2046,7 +2053,7 @@ test "window_add queues list_windows when queue empty" {
 }
 
 test "window_add queues list_windows when queue not empty" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
@@ -2102,7 +2109,7 @@ test "window_add queues list_windows when queue not empty" {
 }
 
 test "two pane flow with pane state" {
-    var viewer = try Viewer.init(testing.allocator);
+    var viewer = try Viewer.init(testing.io, testing.allocator);
     defer viewer.deinit();
 
     try testViewer(&viewer, &.{
diff --git a/src/terminfo/Source.zig b/src/terminfo/Source.zig
index 91fee1ace..922eec016 100644
--- a/src/terminfo/Source.zig
+++ b/src/terminfo/Source.zig
@@ -82,7 +82,8 @@ pub fn xtgettcapMap(comptime self: Source) std.StaticStringMap([]const u8) {
     kvs[2] = .{ "RGB", "8" };
     for (self.capabilities, 3..) |cap, i| {
         kvs[i] = .{
-            cap.name, switch (cap.value) {
+            cap.name,
+            switch (cap.value) {
                 .canceled => @compileError("canceled not handled yet"),
                 .boolean => "",
                 .string => |v| string: {
diff --git a/src/termio/Exec.zig b/src/termio/Exec.zig
index 0894f87b1..7b520a759 100644
--- a/src/termio/Exec.zig
+++ b/src/termio/Exec.zig
@@ -9,7 +9,8 @@ const assert = @import("../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
 const posix = std.posix;
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 const apprt = @import("../apprt.zig");
 const build_config = @import("../build_config.zig");
 const configpkg = @import("../config.zig");
@@ -24,10 +25,11 @@ const Command = @import("../Command.zig");
 const SegmentedPool = @import("../datastruct/main.zig").SegmentedPool;
 const ptypkg = @import("../pty.zig");
 const Pty = ptypkg.Pty;
-const EnvMap = std.process.EnvMap;
+const EnvMap = std.process.Environ.Map;
 const PasswdEntry = internal_os.passwd.Entry;
 const windows = internal_os.windows;
 const ProcessInfo = @import("../pty.zig").ProcessInfo;
+const compat_fd = @import("../lib/compat/fd.zig");
 
 const log = std.log.scoped(.io_exec);
 
@@ -98,7 +100,7 @@ pub fn threadEnter(
 
         // We're in the child. Nothing more we can do but abnormal exit.
         // The Command will output some additional information.
-        posix.exit(1);
+        std.process.exit(1);
     };
     errdefer self.subprocess.stop();
 
@@ -117,13 +119,13 @@ pub fn threadEnter(
     errdefer if (process) |*p| p.deinit();
 
     // Track our process start time for abnormal exits
-    const process_start = try std.time.Instant.now();
+    const process_start: std.Io.Timestamp = .now(global.io(), .awake);
 
     // Create our pipe that we'll use to kill our read thread.
     // pipe[0] is the read end, pipe[1] is the write end.
     const pipe = try internal_os.pipe();
-    errdefer posix.close(pipe[0]);
-    errdefer posix.close(pipe[1]);
+    errdefer _ = posix.system.close(pipe[0]);
+    errdefer _ = posix.system.close(pipe[1]);
 
     // Setup our stream so that we can write.
     var stream = xev.Stream.initFd(pty_fds.write);
@@ -141,7 +143,7 @@ pub fn threadEnter(
         if (builtin.os.tag == .windows) ReadThread.threadMainWindows else ReadThread.threadMainPosix,
         .{ pty_fds.read, io, pipe[0] },
     );
-    read_thread.setName("io-reader") catch {};
+    read_thread.setName(global.io(), "io-reader") catch {};
 
     // Setup our threadata backend state to be our own
     td.backend = .{ .exec = .{
@@ -202,22 +204,23 @@ pub fn threadExit(self: *Exec, td: *termio.Termio.ThreadData) void {
     // Quit our read thread after exiting the subprocess so that
     // we don't get stuck waiting for data to stop flowing if it is
     // a particularly noisy process.
-    _ = posix.write(exec.read_thread_pipe, "x") catch |err| switch (err) {
-        // BrokenPipe means that our read thread is closed already,
-        // which is completely fine since that is what we were trying
-        // to achieve.
-        error.BrokenPipe => {},
+    switch (posix.errno(posix.system.write(exec.read_thread_pipe, "x", 1))) {
+        .SUCCESS => {},
 
-        else => log.warn(
-            "error writing to read thread quit pipe err={}",
-            .{err},
+        // EPIPE means that our read thread is closed already, which is
+        // completely fine since that is what we were trying to achieve.
+        .PIPE => {},
+
+        else => |e| log.warn(
+            "error writing to read thread quit pipe err=E{s}",
+            .{@tagName(e)},
         ),
-    };
+    }
 
     if (comptime builtin.os.tag == .windows) {
         // Interrupt the blocking read so the thread can see the quit message
-        if (windows.kernel32.CancelIoEx(exec.read_thread_fd, null) == 0) {
-            switch (windows.kernel32.GetLastError()) {
+        if (windows.exp.kernel32.CancelIoEx(exec.read_thread_fd, null) == windows.FALSE) {
+            switch (windows.GetLastError()) {
                 .NOT_FOUND => {},
                 else => |err| log.warn("error interrupting read thread err={}", .{err}),
             }
@@ -275,23 +278,18 @@ fn processExitCommon(td: *termio.Termio.ThreadData, exit_code: u32) void {
     execdata.exited = true;
 
     // Determine how long the process was running for.
-    const runtime_ms: ?u64 = runtime: {
-        const process_end = std.time.Instant.now() catch break :runtime null;
-        const runtime_ns = process_end.since(execdata.start);
-        const runtime_ms = runtime_ns / std.time.ns_per_ms;
-        break :runtime runtime_ms;
-    };
-    log.debug(
-        "child process exited status={} runtime={}ms",
-        .{ exit_code, runtime_ms orelse 0 },
+    const runtime_ms: u64 = @max(
+        0,
+        execdata.start.untilNow(global.io(), .awake).toMilliseconds(),
     );
+    log.debug("child process exited status={} runtime={}ms", .{ exit_code, runtime_ms });
 
     // We always notify the surface immediately that the child has
     // exited and some metadata about the exit.
     _ = td.surface_mailbox.push(.{
         .child_exited = .{
             .exit_code = exit_code,
-            .runtime_ms = runtime_ms orelse 0,
+            .runtime_ms = runtime_ms,
         },
     }, .{ .forever = {} });
 }
@@ -372,8 +370,8 @@ fn termiosTimer(
         // If our password input state changed on the terminal then
         // we notify the surface.
         {
-            td.renderer_state.mutex.lock();
-            defer td.renderer_state.mutex.unlock();
+            td.renderer_state.mutex.lockUncancelable(global.io());
+            defer td.renderer_state.mutex.unlock(global.io());
             const t = td.renderer_state.terminal;
             if (t.flags.password_input == password_input) {
                 break :mode_change;
@@ -499,7 +497,7 @@ pub const ThreadData = struct {
     const WRITE_REQ_PREALLOC = std.math.pow(usize, 2, 5);
 
     /// Process start time and boolean of whether its already exited.
-    start: std.time.Instant,
+    start: std.Io.Timestamp,
     exited: bool = false,
 
     /// The data stream is the main IO for the pty.
@@ -541,7 +539,7 @@ pub const ThreadData = struct {
     termios_mode: ptypkg.Mode = .{},
 
     pub fn deinit(self: *ThreadData, alloc: Allocator) void {
-        posix.close(self.read_thread_pipe);
+        _ = posix.system.close(self.read_thread_pipe);
 
         // Clear our write pools. We know we aren't ever going to do
         // any more IO since we stop our data stream below so we can just
@@ -671,10 +669,13 @@ const Subprocess = struct {
             }
 
             var exe_buf: [std.fs.max_path_bytes]u8 = undefined;
-            const exe_bin_path = std.fs.selfExePath(&exe_buf) catch |err| {
+            const exe_bin_path = exe_buf[0 .. std.process.executablePath(
+                global.io(),
+                &exe_buf,
+            ) catch |err| {
                 log.warn("failed to get ghostty exe path err={}", .{err});
                 break :ghostty_path;
-            };
+            }];
             const exe_dir = std.fs.path.dirname(exe_bin_path) orelse break :ghostty_path;
             log.debug("appending ghostty bin to path dir={s}", .{exe_dir});
 
@@ -695,7 +696,7 @@ const Subprocess = struct {
 
                 try env.put(
                     "PATH",
-                    try internal_os.appendEnv(alloc, path, exe_dir),
+                    try appendEnv(alloc, path, exe_dir),
                 );
             } else {
                 try env.put("PATH", exe_dir);
@@ -713,7 +714,7 @@ const Subprocess = struct {
             if (std.fmt.bufPrint(&buf, "{s}/..", .{resources_dir})) |data_dir| {
                 try env.put(
                     xdg_data_dir_key,
-                    try internal_os.appendEnv(
+                    try appendEnv(
                         alloc,
                         env.get(xdg_data_dir_key) orelse "/usr/local/share:/usr/share",
                         data_dir,
@@ -730,7 +731,7 @@ const Subprocess = struct {
                 // path instead of overriding all paths set by OS.
                 try env.put(
                     manpath_key,
-                    try internal_os.appendEnvAlways(
+                    try appendEnvAlways(
                         alloc,
                         env.get(manpath_key) orelse "",
                         man_dir,
@@ -749,7 +750,7 @@ const Subprocess = struct {
         // VTE_VERSION is set by gnome-terminal and other VTE-based terminals.
         // We don't want our child processes to think we're running under VTE.
         // This is not apprt-specific, so we do it here.
-        env.remove("VTE_VERSION");
+        _ = env.orderedRemove("VTE_VERSION");
 
         // Setup our shell integration, if we can.
         const shell_command: configpkg.Command = shell: {
@@ -907,7 +908,7 @@ const Subprocess = struct {
         self.pty = pty;
         errdefer if (!in_child) {
             if (comptime builtin.os.tag != .windows) {
-                _ = posix.close(pty.slave);
+                _ = posix.system.close(pty.slave);
             }
 
             pty.deinit();
@@ -921,7 +922,7 @@ const Subprocess = struct {
                 // Once our subcommand is started we can close the slave
                 // side. This prevents the slave fd from being leaked to
                 // future children.
-                _ = posix.close(pty.slave);
+                _ = posix.system.close(pty.slave);
             }
 
             // Successful start we can clear out some memory.
@@ -944,8 +945,12 @@ const Subprocess = struct {
                 //
                 // https://docs.flatpak.org/en/latest/sandbox-permissions.html#reserved-paths
                 log.info("flatpak detected, will use host command to verify cwd access", .{});
-                const dev_null = try std.fs.cwd().openFile("/dev/null", .{ .mode = .read_write });
-                defer dev_null.close();
+                const dev_null = try std.Io.Dir.cwd().openFile(
+                    global.io(),
+                    "/dev/null",
+                    .{ .mode = .read_write },
+                );
+                defer dev_null.close(global.io());
                 var cmd: internal_os.FlatpakHostCommand = .{
                     .argv = &[_][]const u8{
                         "/bin/sh",
@@ -966,7 +971,7 @@ const Subprocess = struct {
                 break :cwd proposed;
             }
 
-            if (std.fs.cwd().access(proposed, .{})) {
+            if (std.Io.Dir.cwd().access(global.io(), proposed, .{})) {
                 break :cwd proposed;
             } else |err| {
                 log.warn("cannot access cwd, ignoring: {}", .{err});
@@ -1011,9 +1016,18 @@ const Subprocess = struct {
             .args = self.args,
             .env = if (self.env) |*env| env else null,
             .cwd = cwd,
-            .stdin = if (builtin.os.tag == .windows) null else .{ .handle = pty.slave },
-            .stdout = if (builtin.os.tag == .windows) null else .{ .handle = pty.slave },
-            .stderr = if (builtin.os.tag == .windows) null else .{ .handle = pty.slave },
+            .stdin = if (builtin.os.tag == .windows) null else .{
+                .handle = pty.slave,
+                .flags = .{ .nonblocking = false },
+            },
+            .stdout = if (builtin.os.tag == .windows) null else .{
+                .handle = pty.slave,
+                .flags = .{ .nonblocking = false },
+            },
+            .stderr = if (builtin.os.tag == .windows) null else .{
+                .handle = pty.slave,
+                .flags = .{ .nonblocking = false },
+            },
             .pseudo_console = if (builtin.os.tag == .windows) pty.pseudo_console else {},
             .os_pre_exec = switch (comptime builtin.os.tag) {
                 .windows => null,
@@ -1140,8 +1154,8 @@ const Subprocess = struct {
         if (command.pid) |pid| {
             switch (builtin.os.tag) {
                 .windows => {
-                    if (windows.kernel32.TerminateProcess(pid, 0) == 0) {
-                        return windows.unexpectedError(windows.kernel32.GetLastError());
+                    if (windows.exp.kernel32.TerminateProcess(pid, 0) == windows.FALSE) {
+                        return windows.unexpectedError(windows.GetLastError());
                     }
 
                     _ = try command.wait(false);
@@ -1182,10 +1196,14 @@ const Subprocess = struct {
             // The gist is that it lets us detect when children
             // are still alive without blocking so that we can
             // kill them again.
-            const res = posix.waitpid(pid, std.c.W.NOHANG);
-            log.debug("waitpid result={}", .{res.pid});
-            if (res.pid != 0) break;
-            std.Thread.sleep(10 * std.time.ns_per_ms);
+            const res_pid = while (true) {
+                const rc = posix.system.waitpid(pid, null, std.c.W.NOHANG);
+                if (posix.errno(rc) == .INTR) continue;
+                break rc;
+            };
+            log.debug("waitpid result={}", .{res_pid});
+            if (res_pid != 0) break;
+            try std.Io.sleep(global.io(), .fromMilliseconds(10), .awake);
         }
     }
 
@@ -1205,7 +1223,7 @@ const Subprocess = struct {
             const pgid = c.getpgid(pid);
             if (pgid == my_pgid) {
                 log.warn("pgid is our own, retrying", .{});
-                std.Thread.sleep(10 * std.time.ns_per_ms);
+                std.Io.sleep(global.io(), .fromMilliseconds(10), .awake) catch {};
                 continue;
             }
 
@@ -1336,15 +1354,15 @@ pub const ReadThread = struct {
     /// stage at a time, so buffer contents need no locking. Only the
     /// ring metadata is guarded by the mutex.
     const Pipeline = struct {
-        mutex: std.Thread.Mutex = .{},
+        mutex: std.Io.Mutex = .init,
 
         /// Signaled when a batch is published or the gather stage is
         /// done. Waited on by the parse stage.
-        batch_ready: std.Thread.Condition = .{},
+        batch_ready: std.Io.Condition = .init,
 
         /// Signaled when a batch has been consumed. Waited on by the
         /// gather stage when all buffers are in flight (backpressure).
-        slot_free: std.Thread.Condition = .{},
+        slot_free: std.Io.Condition = .init,
 
         /// The number of valid bytes in each buffer. Set at publish
         /// time by the gather stage, read by the parse stage.
@@ -1385,7 +1403,7 @@ pub const ReadThread = struct {
 
     fn threadMainPosix(fd: posix.fd_t, io: *termio.Termio, quit: posix.fd_t) void {
         // Always close our end of the pipe when we exit.
-        defer posix.close(quit);
+        defer _ = posix.system.close(quit);
 
         // Right now, on Darwin, `std.Thread.setName` can only name the current
         // thread, and we have no way to get the current thread from within it,
@@ -1419,7 +1437,7 @@ pub const ReadThread = struct {
         // can't create it we still run correctly, bridge polls are
         // just bounded by their timeout instead of being interrupted
         // when the parse stage goes idle.
-        if (posix.pipe2(.{
+        if (compat_fd.pipe2(.{
             .CLOEXEC = true,
             .NONBLOCK = true,
         })) |fds| {
@@ -1429,8 +1447,8 @@ pub const ReadThread = struct {
             log.warn("read thread failed to create idle pipe err={}", .{err});
         }
         defer if (pipeline.idle_read_fd >= 0) {
-            posix.close(pipeline.idle_read_fd);
-            posix.close(pipeline.idle_write_fd);
+            compat_fd.close(pipeline.idle_read_fd);
+            compat_fd.close(pipeline.idle_write_fd);
         };
 
         const gather_thread = std.Thread.spawn(
@@ -1446,7 +1464,7 @@ pub const ReadThread = struct {
         };
         defer gather_thread.join();
         if (comptime !builtin.os.tag.isDarwin()) {
-            gather_thread.setName("io-gather") catch {};
+            gather_thread.setName(global.io(), "io-gather") catch {};
         }
 
         // This thread is the parse stage. We consume batches in ring
@@ -1454,11 +1472,11 @@ pub const ReadThread = struct {
         // the ring is drained.
         while (true) {
             const batch: []const u8 = batch: {
-                pipeline.mutex.lock();
-                defer pipeline.mutex.unlock();
+                pipeline.mutex.lockUncancelable(global.io());
+                defer pipeline.mutex.unlock(global.io());
                 while (pipeline.count == 0) {
                     if (pipeline.done) return;
-                    pipeline.batch_ready.wait(&pipeline.mutex);
+                    pipeline.batch_ready.waitUncancelable(global.io(), &pipeline.mutex);
                 }
                 const slot = pipeline.tail;
                 break :batch pipeline.bufs[slot][0..pipeline.lens[slot]];
@@ -1469,27 +1487,27 @@ pub const ReadThread = struct {
             io.processOutput(batch);
 
             {
-                pipeline.mutex.lock();
+                pipeline.mutex.lockUncancelable(global.io());
                 pipeline.tail = (pipeline.tail + 1) % buffer_count;
                 pipeline.count -= 1;
                 const wake = pipeline.count == 0 and
                     pipeline.bridging and
                     pipeline.idle_write_fd >= 0;
-                pipeline.mutex.unlock();
-                pipeline.slot_free.signal();
+                pipeline.mutex.unlock(global.io());
+                pipeline.slot_free.signal(global.io());
 
                 // We ran out of batches while the gather stage is
                 // bridging a refill gap: interrupt its poll so it
                 // delivers what it has instead of sleeping out the
                 // timeout while we sit idle.
                 if (wake) {
-                    _ = posix.write(pipeline.idle_write_fd, "i") catch {};
+                    _ = posix.system.write(pipeline.idle_write_fd, "i", 1);
                 }
             }
 
             // Batch boundary: hand the renderer state mutex off if
             // the renderer is waiting. See renderer.State.lockDemand.
-            io.renderer_state.yieldToDemand();
+            io.renderer_state.yieldToDemand(global.io());
         }
     }
 
@@ -1506,10 +1524,10 @@ pub const ReadThread = struct {
         // However we exit, tell the parse stage the stream is over so
         // it drains the ring and joins us.
         defer {
-            pipeline.mutex.lock();
+            pipeline.mutex.lockUncancelable(global.io());
             pipeline.done = true;
-            pipeline.mutex.unlock();
-            pipeline.batch_ready.signal();
+            pipeline.mutex.unlock(global.io());
+            pipeline.batch_ready.signal(global.io());
         }
 
         // The fds we poll: data on the pty, our quit notification,
@@ -1528,16 +1546,16 @@ pub const ReadThread = struct {
             // we should stop reading and let the kernel queue exert
             // backpressure on the child.
             const buf: *[buffer_capacity]u8 = buf: {
-                pipeline.mutex.lock();
-                defer pipeline.mutex.unlock();
+                pipeline.mutex.lockUncancelable(global.io());
+                defer pipeline.mutex.unlock(global.io());
                 while (pipeline.count == buffer_count) {
-                    pipeline.slot_free.wait(&pipeline.mutex);
+                    pipeline.slot_free.waitUncancelable(global.io(), &pipeline.mutex);
                 }
                 break :buf &pipeline.bufs[pipeline.head];
             };
 
             var total: usize = 0;
-            var bridge_start: ?std.time.Instant = null;
+            var bridge_start: ?std.Io.Timestamp = null;
             var spins: usize = 0;
             var fatal = false;
 
@@ -1566,10 +1584,9 @@ pub const ReadThread = struct {
 
                         // Still dry, so we want to sleep in poll for
                         // the next refill, within our latency budget.
-                        const now = std.time.Instant.now() catch
-                            break :gather;
+                        const now = std.Io.Timestamp.now(global.io(), .awake);
                         if (bridge_start) |start| {
-                            if (now.since(start) >= gather_budget_ns)
+                            if (start.durationTo(now).toNanoseconds() >= gather_budget_ns)
                                 break :gather;
                         } else bridge_start = now;
 
@@ -1587,8 +1604,8 @@ pub const ReadThread = struct {
                         // the idle wake so it can interrupt our poll
                         // the moment that changes.
                         {
-                            pipeline.mutex.lock();
-                            defer pipeline.mutex.unlock();
+                            pipeline.mutex.lockUncancelable(global.io());
+                            defer pipeline.mutex.unlock(global.io());
                             if (pipeline.count == 0) break :gather;
                             pipeline.bridging = true;
                         }
@@ -1671,12 +1688,12 @@ pub const ReadThread = struct {
             // Publish the batch (if any) to the parse stage and rotate
             // to the next buffer.
             if (total > 0) {
-                pipeline.mutex.lock();
+                pipeline.mutex.lockUncancelable(global.io());
                 pipeline.lens[pipeline.head] = total;
                 pipeline.head = (pipeline.head + 1) % buffer_count;
                 pipeline.count += 1;
-                pipeline.mutex.unlock();
-                pipeline.batch_ready.signal();
+                pipeline.mutex.unlock(global.io());
+                pipeline.batch_ready.signal(global.io());
             }
 
             if (fatal) return;
@@ -1710,8 +1727,8 @@ pub const ReadThread = struct {
     /// Clears the bridging flag armed before a bridge poll, closing
     /// the window in which the parse stage writes idle wakes.
     fn clearBridging(pipeline: *Pipeline) void {
-        pipeline.mutex.lock();
-        defer pipeline.mutex.unlock();
+        pipeline.mutex.lockUncancelable(global.io());
+        defer pipeline.mutex.unlock(global.io());
         pipeline.bridging = false;
     }
 
@@ -1730,30 +1747,29 @@ pub const ReadThread = struct {
 
     /// Sets the fd to non-blocking mode. Returns false on failure.
     fn setNonblock(fd: posix.fd_t) bool {
-        const flags = posix.fcntl(
-            fd,
-            posix.F.GETFL,
-            0,
-        ) catch |err| {
-            log.warn("read thread failed to get flags err={}", .{err});
+        const flags = posix.system.fcntl(fd, posix.F.GETFL);
+        if (flags == -1) {
+            log.warn("read thread failed to get flags err=E{s}", .{@tagName(posix.errno(-1))});
             return false;
-        };
+        }
 
-        _ = posix.fcntl(
+        switch (posix.errno(posix.system.fcntl(
             fd,
             posix.F.SETFL,
             flags | @as(u32, @bitCast(posix.O{ .NONBLOCK = true })),
-        ) catch |err| {
-            log.warn("read thread failed to set flags err={}", .{err});
-            return false;
-        };
-
+        ))) {
+            .SUCCESS => {},
+            else => |e| {
+                log.warn("read thread failed to set flags err=E{s}", .{@tagName(e)});
+                return false;
+            },
+        }
         return true;
     }
 
     fn threadMainWindows(fd: posix.fd_t, io: *termio.Termio, quit: posix.fd_t) void {
         // Always close our end of the pipe when we exit.
-        defer posix.close(quit);
+        defer _ = posix.system.close(quit);
 
         // Setup our crash metadata
         crash.sentry.thread_state = .{
@@ -1766,8 +1782,8 @@ pub const ReadThread = struct {
         while (true) {
             while (true) {
                 var n: windows.DWORD = 0;
-                if (windows.kernel32.ReadFile(fd, &buf, buf.len, &n, null) == 0) {
-                    const err = windows.kernel32.GetLastError();
+                if (windows.exp.kernel32.ReadFile(fd, &buf, buf.len, &n, null) == windows.FALSE) {
+                    const err = windows.GetLastError();
                     switch (err) {
                         // Check for a quit signal
                         .OPERATION_ABORTED => break,
@@ -1784,12 +1800,12 @@ pub const ReadThread = struct {
                 // See threadMainPosix: hand the renderer state mutex
                 // off if the renderer is waiting, since this loop
                 // would otherwise starve it under heavy output.
-                io.renderer_state.yieldToDemand();
+                io.renderer_state.yieldToDemand(global.io());
             }
 
             var quit_bytes: windows.DWORD = 0;
-            if (windows.exp.kernel32.PeekNamedPipe(quit, null, 0, null, &quit_bytes, null) == 0) {
-                const err = windows.kernel32.GetLastError();
+            if (windows.exp.kernel32.PeekNamedPipe(quit, null, 0, null, &quit_bytes, null) == windows.FALSE) {
+                const err = windows.GetLastError();
                 log.err("quit pipe reader error err={}", .{err});
                 unreachable;
             }
@@ -1837,16 +1853,16 @@ fn execCommand(
         };
 
         const hush = if (passwd.home) |home| hush: {
-            var dir = std.fs.openDirAbsolute(home, .{}) catch |err| {
+            var dir = std.Io.Dir.openDirAbsolute(global.io(), home, .{}) catch |err| {
                 log.warn(
                     "failed to open home dir, not checking for hushlogin err={}",
                     .{err},
                 );
                 break :hush false;
             };
-            defer dir.close();
+            defer dir.close(global.io());
 
-            break :hush if (dir.access(".hushlogin", .{})) true else |_| false;
+            break :hush if (dir.access(global.io(), ".hushlogin", .{})) true else |_| false;
         } else false;
 
         // If we made it this far we're going to start building
@@ -1945,7 +1961,7 @@ fn execCommand(
 
     return switch (command) {
         // We need to clone the command since there's no guarantee the config remains valid.
-        .direct => |_| (try command.clone(alloc)).direct,
+        .direct => (try command.clone(alloc)).direct,
 
         .shell => |v| shell: {
             var args: std.ArrayList([:0]const u8) = try .initCapacity(alloc, 4);
@@ -1973,7 +1989,7 @@ fn execCommand(
                     // Other values are passed as-is and resolved by
                     // `internal_os.path.expand` in Command.startWindows.
                     const argv0 = if (std.ascii.eqlIgnoreCase(v, "cmd.exe"))
-                        std.process.getEnvVarOwned(alloc, "COMSPEC") catch
+                        global.environ().getAlloc(alloc, "COMSPEC") catch
                             try alloc.dupe(u8, v)
                     else
                         try alloc.dupe(u8, v);
@@ -2002,6 +2018,37 @@ fn execCommand(
     };
 }
 
+/// Append a value to an environment variable such as PATH.
+/// The returned value is always allocated so it must be freed.
+fn appendEnv(
+    alloc: Allocator,
+    current: []const u8,
+    value: []const u8,
+) Allocator.Error![]u8 {
+    // If there is no prior value, we return it as-is
+    if (current.len == 0) return try alloc.dupe(u8, value);
+
+    // Otherwise we must prefix.
+    return try appendEnvAlways(alloc, current, value);
+}
+
+/// Always append value to environment, even when it is empty.
+/// This is useful because some env vars (like MANPATH) want there
+/// to be an empty prefix to preserve existing values.
+///
+/// The returned value is always allocated so it must be freed.
+fn appendEnvAlways(
+    alloc: Allocator,
+    current: []const u8,
+    value: []const u8,
+) Allocator.Error![]u8 {
+    return try std.fmt.allocPrint(alloc, "{s}{c}{s}", .{
+        current,
+        std.fs.path.delimiter,
+        value,
+    });
+}
+
 /// Get information about the process(es) running within the backend. Returns
 /// `null` if there was an error getting the information or the information is
 /// not available on a particular platform.
@@ -2190,7 +2237,7 @@ test "execCommand windows: bare cmd.exe resolves via COMSPEC" {
     try testing.expectEqual(1, result.len);
 
     // Expect COMSPEC if available, otherwise the documented fallback.
-    const expected = std.process.getEnvVarOwned(alloc, "COMSPEC") catch
+    const expected = testing.environ.getAlloc(alloc, "COMSPEC") catch
         try alloc.dupe(u8, "C:\\Windows\\System32\\cmd.exe");
     try testing.expectEqualStrings(expected, result[0]);
 }
diff --git a/src/termio/Termio.zig b/src/termio/Termio.zig
index 3f8b3d418..5d7a47d25 100644
--- a/src/termio/Termio.zig
+++ b/src/termio/Termio.zig
@@ -8,18 +8,20 @@ const std = @import("std");
 const assert = @import("../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
-const EnvMap = std.process.EnvMap;
+const EnvMap = std.process.Environ.Map;
 const posix = std.posix;
 const termio = @import("../termio.zig");
 const StreamHandler = @import("stream_handler.zig").StreamHandler;
 const terminalpkg = @import("../terminal/main.zig");
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 const renderer = @import("../renderer.zig");
 const apprt = @import("../apprt.zig");
 const internal_os = @import("../os/main.zig");
 const windows = internal_os.windows;
 const configpkg = @import("../config.zig");
 const ProcessInfo = @import("../pty.zig").ProcessInfo;
+const compat_file = @import("../lib/compat/file.zig");
 
 const log = std.log.scoped(.io_exec);
 
@@ -65,7 +67,7 @@ terminal_stream: StreamHandler.Stream,
 
 /// Last time the cursor was reset. This is used to prevent message
 /// flooding with cursor resets.
-last_cursor_reset: ?std.time.Instant = null,
+last_cursor_reset: ?std.Io.Timestamp = null,
 
 /// State we have for thread enter. This may be null if we don't need
 /// to keep track of any state or if its already been freed.
@@ -125,7 +127,8 @@ const ThreadEnterState = struct {
             input[i] = switch (item) {
                 .raw => |v| .{ .string = try alloc.dupe(u8, v) },
                 .path => |path| file: {
-                    const f = std.fs.cwd().openFile(
+                    const f = std.Io.Dir.cwd().openFile(
+                        global.io(),
                         path,
                         .{},
                     ) catch |err| {
@@ -146,7 +149,7 @@ const ThreadEnterState = struct {
 
     const Input = union(enum) {
         string: []const u8,
-        file: std.fs.File,
+        file: std.Io.File,
     };
 };
 
@@ -238,7 +241,7 @@ pub fn init(self: *Termio, alloc: Allocator, opts: termio.Options) !void {
     };
 
     // Create our terminal
-    var term = try terminalpkg.Terminal.init(alloc, opts: {
+    var term = try terminalpkg.Terminal.init(global.io(), alloc, opts: {
         const grid_size = opts.size.grid();
         break :opts .{
             .cols = grid_size.columns,
@@ -258,7 +261,7 @@ pub fn init(self: *Termio, alloc: Allocator, opts: termio.Options) !void {
                 .palette = .init(opts.config.palette),
             },
             .kitty_image_storage_limit = opts.config.image_storage_limit,
-            .kitty_image_loading_limits = .all,
+            .kitty_image_loading_limits = .allWithTempDir(global.tmpDirPath()),
         };
     });
     errdefer term.deinit(alloc);
@@ -361,7 +364,8 @@ pub fn threadEnter(
         },
         .file => |f| self.queueWrite(
             data,
-            f.readToEndAlloc(
+            compat_file.readToEndAlloc(
+                f,
                 self.alloc,
                 10 * 1024 * 1024, // 10 MiB max
             ) catch |err| {
@@ -419,8 +423,8 @@ pub fn changeConfig(self: *Termio, td: *ThreadData, config: *DerivedConfig) !voi
     // The remainder of this function is modifying terminal state or
     // the read thread data, all of which requires holding the renderer
     // state lock.
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
 
     // Deinit our old config. We do this in the lock because the
     // stream handler may be referencing the old config (i.e. enquiry resp)
@@ -453,7 +457,7 @@ pub fn changeConfig(self: *Termio, td: *ThreadData, config: *DerivedConfig) !voi
 
     // Set the image limits
     try self.terminal.setKittyGraphicsSizeLimit(self.alloc, config.image_storage_limit);
-    self.terminal.setKittyGraphicsLoadingLimits(.all);
+    self.terminal.setKittyGraphicsLoadingLimits(.allWithTempDir(global.tmpDirPath()));
 }
 
 /// Resize the terminal.
@@ -470,8 +474,8 @@ pub fn resize(
 
     // Enter the critical area that we want to keep small
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // Update the size of our terminal state
         try self.terminal.resize(
@@ -493,14 +497,14 @@ pub fn resize(
     }
 
     // Mail the renderer so that it can update the GPU and re-render
-    _ = self.renderer_mailbox.push(.{ .resize = size }, .{ .forever = {} });
+    _ = self.renderer_mailbox.push(global.io(), .{ .resize = size }, .{ .forever = {} });
     self.renderer_wakeup.notify() catch {};
 }
 
 /// Make a size report.
 pub fn sizeReport(self: *Termio, td: *ThreadData, style: termio.Message.SizeReport) !void {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     try self.sizeReportLocked(td, style);
 }
 
@@ -529,8 +533,8 @@ fn sizeReportLocked(self: *Termio, td: *ThreadData, style: termio.Message.SizeRe
 /// Reset the synchronized output mode. This is usually called by timer
 /// expiration from the termio thread.
 pub fn resetSynchronizedOutput(self: *Termio) void {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     self.terminal.modes.set(.synchronized_output, false);
     self.renderer_wakeup.notify() catch {};
 }
@@ -538,8 +542,8 @@ pub fn resetSynchronizedOutput(self: *Termio) void {
 /// Clear the screen.
 pub fn clearScreen(self: *Termio, td: *ThreadData, history: bool) !void {
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
 
         // If we're on the alternate screen, we do not clear. Since this is an
         // emulator-level screen clear, this messes up the running programs
@@ -568,6 +572,7 @@ pub fn clearScreen(self: *Termio, td: *ThreadData, history: bool) !void {
             // all of them. We delete all of them for now but if this behavior
             // isn't fully correct we should fix this later.
             self.terminal.screens.active.kitty_images.delete(
+                self.terminal.io(),
                 self.terminal.screens.active.alloc,
                 &self.terminal,
                 .{ .all = true },
@@ -595,16 +600,16 @@ pub fn scrollViewport(
     self: *Termio,
     scroll: terminalpkg.Terminal.ScrollViewport,
 ) void {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     self.terminal.scrollViewport(scroll);
 }
 
 /// Jump the viewport to the prompt.
 pub fn jumpToPrompt(self: *Termio, delta: isize) !void {
     {
-        self.renderer_state.mutex.lock();
-        defer self.renderer_state.mutex.unlock();
+        self.renderer_state.mutex.lockUncancelable(global.io());
+        defer self.renderer_state.mutex.unlock(global.io());
         self.terminal.screens.active.scroll(.{ .delta_prompt = delta });
     }
 
@@ -613,9 +618,9 @@ pub fn jumpToPrompt(self: *Termio, delta: isize) !void {
 
 /// Called when focus is gained or lost (when focus events are enabled)
 pub fn focusGained(self: *Termio, td: *ThreadData, focused: bool) !void {
-    self.renderer_state.mutex.lock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
     const focus_event = self.renderer_state.terminal.modes.get(.focus_event);
-    self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.unlock(global.io());
 
     // If we have focus events enabled, we send the focus event.
     if (focus_event) {
@@ -638,8 +643,8 @@ pub fn focusGained(self: *Termio, td: *ThreadData, focused: bool) !void {
 pub fn processOutput(self: *Termio, buf: []const u8) void {
     // We are modifying terminal state from here on out and we need
     // the lock to grab our read data.
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
     self.processOutputLocked(buf);
 }
 
@@ -652,19 +657,18 @@ fn processOutputLocked(self: *Termio, buf: []const u8) void {
     // non-blink state so it is rendered if visible. If we're under
     // HEAVY read load, we don't want to send a ton of these so we
     // use a timer under the covers
-    if (std.time.Instant.now()) |now| cursor_reset: {
+    const now = std.Io.Timestamp.now(global.io(), .awake);
+    cursor_reset: {
         if (self.last_cursor_reset) |last| {
-            if (now.since(last) <= (500 * std.time.ns_per_ms)) {
+            if (last.durationTo(now).toMilliseconds() <= 500) {
                 break :cursor_reset;
             }
         }
 
         self.last_cursor_reset = now;
-        _ = self.renderer_mailbox.push(.{
+        _ = self.renderer_mailbox.push(global.io(), .{
             .reset_cursor_blink = {},
         }, .{ .instant = {} });
-    } else |err| {
-        log.warn("failed to get current time err={}", .{err});
     }
 
     // If we have an inspector, we enter SLOW MODE because we need to
@@ -697,8 +701,8 @@ fn processOutputLocked(self: *Termio, buf: []const u8) void {
 
 /// Sends a DSR response for the current color scheme to the pty.
 pub fn colorSchemeReport(self: *Termio, td: *ThreadData, force: bool) !void {
-    self.renderer_state.mutex.lock();
-    defer self.renderer_state.mutex.unlock();
+    self.renderer_state.mutex.lockUncancelable(global.io());
+    defer self.renderer_state.mutex.unlock(global.io());
 
     try self.colorSchemeReportLocked(td, force);
 }
diff --git a/src/termio/Thread.zig b/src/termio/Thread.zig
index ce4c1f4af..4f5982208 100644
--- a/src/termio/Thread.zig
+++ b/src/termio/Thread.zig
@@ -14,7 +14,8 @@ pub const Thread = @This();
 const std = @import("std");
 const ArenaAllocator = std.heap.ArenaAllocator;
 const builtin = @import("builtin");
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 const crash = @import("../crash/main.zig");
 const internal_os = @import("../os/main.zig");
 const termio = @import("../termio.zig");
@@ -147,8 +148,8 @@ pub fn threadMain(self: *Thread, io: *termio.Termio) void {
         // the error to the surface thread and let the apprt deal with it
         // in some way but this works for now. Without this, the user would
         // just see a blank terminal window.
-        io.renderer_state.mutex.lock();
-        defer io.renderer_state.mutex.unlock();
+        io.renderer_state.mutex.lockUncancelable(global.io());
+        defer io.renderer_state.mutex.unlock(global.io());
         const t = io.renderer_state.terminal;
 
         // Hide the cursor
@@ -297,7 +298,7 @@ fn drainMailbox(
 
     // If we're draining, we just drain the mailbox and return.
     if (self.flags.drain) {
-        while (mailbox.pop()) |_| {}
+        while (mailbox.pop(global.io())) |_| {}
         return;
     }
 
@@ -305,7 +306,7 @@ fn drainMailbox(
     // expectation is that all our message handlers will be non-blocking
     // ENOUGH to not mess up throughput on producers.
     var redraw: bool = false;
-    while (mailbox.pop()) |message| {
+    while (mailbox.pop(global.io())) |message| {
         // If we have a message we always redraw
         redraw = true;
 
diff --git a/src/termio/mailbox.zig b/src/termio/mailbox.zig
index 2725d0241..d5926f3a8 100644
--- a/src/termio/mailbox.zig
+++ b/src/termio/mailbox.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 const renderer = @import("../renderer.zig");
 const termio = @import("../termio.zig");
 const BlockingQueue = @import("../datastruct/main.zig").BlockingQueue;
@@ -61,13 +62,13 @@ pub const Mailbox = union(enum) {
     pub fn send(
         self: *Mailbox,
         msg: termio.Message,
-        mutex: ?*std.Thread.Mutex,
+        mutex: ?*std.Io.Mutex,
     ) void {
         switch (self.*) {
             .spsc => |*mb| send: {
                 // Try to write to the queue with an instant timeout. This is the
                 // fast path because we can queue without a lock.
-                if (mb.queue.push(msg, .{ .instant = {} }) > 0) break :send;
+                if (mb.queue.push(global.io(), msg, .{ .instant = {} }) > 0) break :send;
 
                 // If we enter this conditional, the queue is full. We wake up
                 // the writer thread so that it can process messages to clear up
@@ -87,9 +88,9 @@ pub const Mailbox = union(enum) {
                 // are other messages in the writer queue (resize, focus) that
                 // could acquire the lock. This is why we have to release our lock
                 // here.
-                if (mutex) |m| m.unlock();
-                defer if (mutex) |m| m.lock();
-                _ = mb.queue.push(msg, .{ .forever = {} });
+                if (mutex) |m| m.unlock(global.io());
+                defer if (mutex) |m| m.lockUncancelable(global.io());
+                _ = mb.queue.push(global.io(), msg, .{ .forever = {} });
             },
         }
     }
diff --git a/src/termio/shell_integration.zig b/src/termio/shell_integration.zig
index 2dd09ee29..372ccb41c 100644
--- a/src/termio/shell_integration.zig
+++ b/src/termio/shell_integration.zig
@@ -2,10 +2,11 @@ const std = @import("std");
 const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
-const EnvMap = std.process.EnvMap;
+const EnvMap = std.process.Environ.Map;
 const config = @import("../config.zig");
 const homedir = @import("../os/homedir.zig");
 const internal_os = @import("../os/main.zig");
+const global = @import("../global.zig");
 
 const log = std.log.scoped(.shell_integration);
 
@@ -97,7 +98,7 @@ test "force shell" {
     inline for (@typeInfo(Shell).@"enum".fields) |field| {
         const shell = @field(Shell, field.name);
 
-        var res: TmpResourcesDir = try .init(alloc, shell);
+        var res: TmpResourcesDir = try .init(shell);
         defer res.deinit();
 
         const result = try setup(
@@ -373,12 +374,12 @@ fn setupBash(
         "{s}/shell-integration/bash/ghostty.bash",
         .{resource_dir},
     );
-    if (std.fs.openFileAbsolute(script_path, .{})) |file| {
-        file.close();
+    if (std.Io.Dir.openFileAbsolute(global.io(), script_path, .{})) |file| {
+        file.close(global.io());
         try env.put("ENV", script_path);
     } else |err| {
         log.warn("unable to open {s}: {}", .{ script_path, err });
-        env.remove("GHOSTTY_BASH_ENV");
+        _ = env.swapRemove("GHOSTTY_BASH_ENV");
         return null;
     }
 
@@ -390,8 +391,10 @@ fn setupBash(
     // In POSIX mode, HISTFILE defaults to ~/.sh_history, so unless we're
     // staying in POSIX mode (--posix), change it back to ~/.bash_history.
     if (env.get("HISTFILE") == null) {
+        var environ_map = try global.environMap();
+        defer environ_map.deinit();
         var home_buf: [1024]u8 = undefined;
-        if (try homedir.home(&home_buf)) |home| {
+        if (try homedir.home(&environ_map, &home_buf)) |home| {
             var histfile_buf: [std.fs.max_path_bytes]u8 = undefined;
             const histfile = try std.fmt.bufPrint(
                 &histfile_buf,
@@ -413,7 +416,7 @@ test "bash" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .bash);
+    var res: TmpResourcesDir = try .init(.bash);
     defer res.deinit();
 
     var env = EnvMap.init(alloc);
@@ -436,7 +439,7 @@ test "bash: unsupported options" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .bash);
+    var res: TmpResourcesDir = try .init(.bash);
     defer res.deinit();
 
     const cmdlines = [_][:0]const u8{
@@ -462,7 +465,7 @@ test "bash: inject flags" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .bash);
+    var res: TmpResourcesDir = try .init(.bash);
     defer res.deinit();
 
     // bash --norc
@@ -492,7 +495,7 @@ test "bash: rcfile" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .bash);
+    var res: TmpResourcesDir = try .init(.bash);
     defer res.deinit();
 
     var env = EnvMap.init(alloc);
@@ -519,7 +522,7 @@ test "bash: HISTFILE" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .bash);
+    var res: TmpResourcesDir = try .init(.bash);
     defer res.deinit();
 
     // HISTFILE unset
@@ -551,7 +554,7 @@ test "bash: ENV" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .bash);
+    var res: TmpResourcesDir = try .init(.bash);
     defer res.deinit();
 
     var env = EnvMap.init(alloc);
@@ -575,7 +578,7 @@ test "bash: additional arguments" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .bash);
+    var res: TmpResourcesDir = try .init(.bash);
     defer res.deinit();
 
     var env = EnvMap.init(alloc);
@@ -603,7 +606,7 @@ test "bash: missing resources" {
     var tmp_dir = testing.tmpDir(.{});
     defer tmp_dir.cleanup();
 
-    const resources_dir = try tmp_dir.dir.realpathAlloc(alloc, ".");
+    const resources_dir = try tmp_dir.dir.realPathFileAlloc(testing.io, ".", alloc);
     defer alloc.free(resources_dir);
 
     var env = EnvMap.init(alloc);
@@ -633,11 +636,15 @@ fn setupXdgDataDirs(
         "{s}/shell-integration",
         .{resource_dir},
     );
-    var integ_dir = std.fs.openDirAbsolute(integ_path, .{}) catch |err| {
+    var integ_dir = std.Io.Dir.openDirAbsolute(
+        global.io(),
+        integ_path,
+        .{},
+    ) catch |err| {
         log.warn("unable to open {s}: {}", .{ integ_path, err });
         return false;
     };
-    integ_dir.close();
+    integ_dir.close(global.io());
 
     // Set an env var so we can remove this from XDG_DATA_DIRS later.
     // This happens in the shell integration config itself. We do this
@@ -659,7 +666,7 @@ fn setupXdgDataDirs(
     const xdg_data_dirs_key = "XDG_DATA_DIRS";
     try env.put(
         xdg_data_dirs_key,
-        try internal_os.prependEnv(
+        try prependEnv(
             stack_alloc,
             env.get(xdg_data_dirs_key) orelse "/usr/local/share:/usr/share",
             integ_path,
@@ -669,6 +676,23 @@ fn setupXdgDataDirs(
     return true;
 }
 
+/// Prepend a value to an environment variable such as PATH.
+/// The returned value is always allocated so it must be freed.
+fn prependEnv(
+    alloc: Allocator,
+    current: []const u8,
+    value: []const u8,
+) Allocator.Error![]u8 {
+    // If there is no prior value, we return it as-is
+    if (current.len == 0) return try alloc.dupe(u8, value);
+
+    return try std.fmt.allocPrint(alloc, "{s}{c}{s}", .{
+        value,
+        std.fs.path.delimiter,
+        current,
+    });
+}
+
 test "xdg: empty XDG_DATA_DIRS" {
     if (builtin.os.tag == .windows) return error.SkipZigTest;
 
@@ -678,7 +702,7 @@ test "xdg: empty XDG_DATA_DIRS" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .fish);
+    var res: TmpResourcesDir = try .init(.fish);
     defer res.deinit();
 
     var env = EnvMap.init(alloc);
@@ -706,7 +730,7 @@ test "xdg: existing XDG_DATA_DIRS" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .fish);
+    var res: TmpResourcesDir = try .init(.fish);
     defer res.deinit();
 
     var env = EnvMap.init(alloc);
@@ -736,7 +760,7 @@ test "xdg: missing resources" {
     var tmp_dir = testing.tmpDir(.{});
     defer tmp_dir.cleanup();
 
-    const resources_dir = try tmp_dir.dir.realpathAlloc(alloc, ".");
+    const resources_dir = try tmp_dir.dir.realPathFileAlloc(testing.io, ".", alloc);
     defer alloc.free(resources_dir);
 
     var env = EnvMap.init(alloc);
@@ -824,7 +848,7 @@ test "nushell" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .nushell);
+    var res: TmpResourcesDir = try .init(.nushell);
     defer res.deinit();
 
     var env = EnvMap.init(alloc);
@@ -850,7 +874,7 @@ test "nushell: unsupported options" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(alloc, .nushell);
+    var res: TmpResourcesDir = try .init(.nushell);
     defer res.deinit();
 
     const cmdlines = [_][:0]const u8{
@@ -879,7 +903,7 @@ test "nushell: missing resources" {
     var tmp_dir = testing.tmpDir(.{});
     defer tmp_dir.cleanup();
 
-    const resources_dir = try tmp_dir.dir.realpathAlloc(alloc, ".");
+    const resources_dir = try tmp_dir.dir.realPathFileAlloc(testing.io, ".", alloc);
     defer alloc.free(resources_dir);
 
     var env = EnvMap.init(alloc);
@@ -910,11 +934,15 @@ fn setupZsh(
         "{s}/shell-integration/zsh",
         .{resource_dir},
     );
-    var integ_dir = std.fs.openDirAbsolute(integ_path, .{}) catch |err| {
+    var integ_dir = std.Io.Dir.openDirAbsolute(
+        global.io(),
+        integ_path,
+        .{},
+    ) catch |err| {
         log.warn("unable to open {s}: {}", .{ integ_path, err });
         return null;
     };
-    integ_dir.close();
+    integ_dir.close(global.io());
     try env.put("ZDOTDIR", integ_path);
 
     return try command.clone(alloc);
@@ -927,7 +955,7 @@ test "zsh" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(testing.allocator, .zsh);
+    var res: TmpResourcesDir = try .init(.zsh);
     defer res.deinit();
 
     var env = EnvMap.init(testing.allocator);
@@ -946,7 +974,7 @@ test "zsh: ZDOTDIR" {
     defer arena.deinit();
     const alloc = arena.allocator();
 
-    var res: TmpResourcesDir = try .init(testing.allocator, .zsh);
+    var res: TmpResourcesDir = try .init(.zsh);
     defer res.deinit();
 
     var env = EnvMap.init(testing.allocator);
@@ -969,7 +997,7 @@ test "zsh: missing resources" {
     var tmp_dir = testing.tmpDir(.{});
     defer tmp_dir.cleanup();
 
-    const resources_dir = try tmp_dir.dir.realpathAlloc(alloc, ".");
+    const resources_dir = try tmp_dir.dir.realPathFileAlloc(testing.io, ".", alloc);
     defer alloc.free(resources_dir);
 
     var env = EnvMap.init(alloc);
@@ -981,12 +1009,11 @@ test "zsh: missing resources" {
 
 /// Test helper that creates a temporary resources directory with shell integration paths.
 const TmpResourcesDir = struct {
-    allocator: Allocator,
     tmp_dir: std.testing.TmpDir,
-    path: []const u8,
+    path: [:0]const u8,
     shell_path: []const u8,
 
-    fn init(allocator: Allocator, shell: Shell) !TmpResourcesDir {
+    fn init(shell: Shell) !TmpResourcesDir {
         var tmp_dir = std.testing.tmpDir(.{});
         errdefer tmp_dir.cleanup();
 
@@ -996,20 +1023,20 @@ const TmpResourcesDir = struct {
             "shell-integration/{s}",
             .{@tagName(shell)},
         );
-        try tmp_dir.dir.makePath(relative_shell_path);
+        try tmp_dir.dir.createDirPath(std.testing.io, relative_shell_path);
 
-        const path = try tmp_dir.dir.realpathAlloc(allocator, ".");
-        errdefer allocator.free(path);
+        const path = try tmp_dir.dir.realPathFileAlloc(std.testing.io, ".", std.testing.allocator);
+        errdefer std.testing.allocator.free(path);
 
         const shell_path = try std.fmt.allocPrint(
-            allocator,
+            std.testing.allocator,
             "{s}/{s}",
             .{ path, relative_shell_path },
         );
-        errdefer allocator.free(shell_path);
+        errdefer std.testing.allocator.free(shell_path);
 
         switch (shell) {
-            .bash => try tmp_dir.dir.writeFile(.{
+            .bash => try tmp_dir.dir.writeFile(std.testing.io, .{
                 .sub_path = "shell-integration/bash/ghostty.bash",
                 .data = "",
             }),
@@ -1017,7 +1044,6 @@ const TmpResourcesDir = struct {
         }
 
         return .{
-            .allocator = allocator,
             .tmp_dir = tmp_dir,
             .path = path,
             .shell_path = shell_path,
@@ -1025,8 +1051,8 @@ const TmpResourcesDir = struct {
     }
 
     fn deinit(self: *TmpResourcesDir) void {
-        self.allocator.free(self.shell_path);
-        self.allocator.free(self.path);
+        std.testing.allocator.free(self.shell_path);
+        std.testing.allocator.free(self.path);
         self.tmp_dir.cleanup();
     }
 };
diff --git a/src/termio/stream_handler.zig b/src/termio/stream_handler.zig
index 91dcb7d3e..58b7fcab4 100644
--- a/src/termio/stream_handler.zig
+++ b/src/termio/stream_handler.zig
@@ -2,7 +2,8 @@ const std = @import("std");
 const builtin = @import("builtin");
 const assert = @import("../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
-const xev = @import("../global.zig").xev;
+const global = @import("../global.zig");
+const xev = global.xev;
 const apprt = @import("../apprt.zig");
 const build_config = @import("../build_config.zig");
 const configpkg = @import("../config.zig");
@@ -118,8 +119,8 @@ pub const StreamHandler = struct {
         // See messageWriter which has similar logic and explains why
         // we may have to do this.
         if (self.surface_mailbox.push(msg, .{ .instant = {} }) == 0) {
-            self.renderer_state.mutex.unlock();
-            defer self.renderer_state.mutex.lock();
+            self.renderer_state.mutex.unlock(global.io());
+            defer self.renderer_state.mutex.lockUncancelable(global.io());
             _ = self.surface_mailbox.push(msg, .{ .forever = {} });
         }
     }
@@ -147,8 +148,8 @@ pub const StreamHandler = struct {
         // Instant would have blocked. Release the renderer mutex,
         // wake up the renderer to allow it to process the message,
         // and then try again.
-        self.renderer_state.mutex.unlock();
-        defer self.renderer_state.mutex.lock();
+        self.renderer_state.mutex.unlock(global.io());
+        defer self.renderer_state.mutex.lockUncancelable(global.io());
         self.renderer_wakeup.notify() catch |err| {
             // This is an EXTREMELY unlikely case. We still don't return
             // and attempt to send the message because its most likely
@@ -392,7 +393,7 @@ pub const StreamHandler = struct {
                         assert(self.tmux_viewer == null);
                         const viewer = try self.alloc.create(terminal.tmux.Viewer);
                         errdefer self.alloc.destroy(viewer);
-                        viewer.* = try .init(self.alloc);
+                        viewer.* = try .init(global.io(), self.alloc);
                         errdefer viewer.deinit();
                         self.tmux_viewer = viewer;
                         break :tmux;
@@ -464,26 +465,25 @@ pub const StreamHandler = struct {
 
             .decrqss => |decrqss| {
                 var response: [128]u8 = undefined;
-                var stream = std.io.fixedBufferStream(&response);
-                const writer = stream.writer();
+                var writer: std.Io.Writer = .fixed(&response);
 
                 // Offset the stream position to just past the response prefix.
                 // We will write the "payload" (if any) below. If no payload is
                 // written then we send an invalid DECRPSS response.
                 const prefix_fmt = "\x1bP{d}$r";
                 const prefix_len = std.fmt.comptimePrint(prefix_fmt, .{0}).len;
-                stream.pos = prefix_len;
+                writer.end = prefix_len;
 
                 switch (decrqss) {
                     // Invalid or unhandled request
                     .none => {},
 
                     .sgr => {
-                        const buf = try self.terminal.printAttributes(stream.buffer[stream.pos..]);
+                        const buf = try self.terminal.printAttributes(writer.buffer[writer.end..]);
 
                         // printAttributes wrote into our buffer, so adjust the stream
                         // position
-                        stream.pos += buf.len;
+                        writer.end += buf.len;
 
                         try writer.writeByte('m');
                     },
@@ -522,14 +522,14 @@ pub const StreamHandler = struct {
                 }
 
                 // Our response is valid if we have a response payload
-                const valid = stream.pos > prefix_len;
+                const valid = writer.end > prefix_len;
 
                 // Write the terminator
                 try writer.writeAll("\x1b\\");
 
                 // Write the response prefix into the buffer
                 _ = try std.fmt.bufPrint(response[0..prefix_len], prefix_fmt, .{@intFromBool(valid)});
-                const msg = try termio.Message.writeReq(self.alloc, response[0..stream.pos]);
+                const msg = try termio.Message.writeReq(self.alloc, response[0..writer.end]);
                 self.messageWriter(msg);
             },
         }
@@ -542,7 +542,7 @@ pub const StreamHandler = struct {
         // log.warn("APC command: {}", .{cmd});
         switch (cmd) {
             .kitty => |*kitty_cmd| {
-                if (self.terminal.kittyGraphics(self.alloc, kitty_cmd)) |resp| {
+                if (self.terminal.kittyGraphics(global.io(), self.alloc, kitty_cmd)) |resp| {
                     var buf: [1024]u8 = undefined;
                     var writer: std.Io.Writer = .fixed(&buf);
                     try resp.encode(&writer);
@@ -1117,22 +1117,18 @@ pub const StreamHandler = struct {
             return;
         }
 
-        var host_buffer: [std.Uri.host_name_max]u8 = undefined;
+        var host_buffer: [std.Io.net.HostName.max_len]u8 = undefined;
         const host = uri.getHost(&host_buffer) catch |err| switch (err) {
             error.UriMissingHost => {
                 log.warn("OSC 7 uri must contain a hostname: {}", .{err});
                 return;
             },
-            error.UriHostTooLong => {
-                log.warn("failed to get full hostname for OSC 7 validation: {}", .{err});
-                return;
-            },
         };
 
         // OSC 7 is a little sketchy because anyone can send any value from
         // any host (such an SSH session). The best practice terminals follow
         // is to valid the hostname to be local.
-        const host_valid = internal_os.hostname.isLocal(host) catch |err| switch (err) {
+        const host_valid = internal_os.hostname.isLocal(host.bytes) catch |err| switch (err) {
             error.PermissionDenied,
             error.Unexpected,
             => {
@@ -1141,7 +1137,7 @@ pub const StreamHandler = struct {
             },
         };
         if (!host_valid) {
-            log.warn("OSC 7 host ({s}) must be local", .{host});
+            log.warn("OSC 7 host ({s}) must be local", .{host.bytes});
             return;
         }
 
@@ -1186,8 +1182,7 @@ pub const StreamHandler = struct {
         var fba: std.heap.FixedBufferAllocator = .init(&buffer);
         const alloc = fba.allocator();
 
-        var response: std.ArrayListUnmanaged(u8) = .empty;
-        const writer = response.writer(alloc);
+        var response: std.Io.Writer.Allocating = .init(alloc);
 
         var it = requests.constIterator(0);
         while (it.next()) |req| {
@@ -1334,7 +1329,7 @@ pub const StreamHandler = struct {
 
                     switch (self.osc_color_report_format) {
                         .@"16-bit" => switch (kind) {
-                            .palette => |i| try writer.print(
+                            .palette => |i| try response.writer.print(
                                 "\x1b]4;{d};rgb:{x:0>4}/{x:0>4}/{x:0>4}",
                                 .{
                                     i,
@@ -1343,7 +1338,7 @@ pub const StreamHandler = struct {
                                     @as(u16, color.b) * 257,
                                 },
                             ),
-                            .dynamic => |dynamic| try writer.print(
+                            .dynamic => |dynamic| try response.writer.print(
                                 "\x1b]{d};rgb:{x:0>4}/{x:0>4}/{x:0>4}",
                                 .{
                                     @intFromEnum(dynamic),
@@ -1356,7 +1351,7 @@ pub const StreamHandler = struct {
                         },
 
                         .@"8-bit" => switch (kind) {
-                            .palette => |i| try writer.print(
+                            .palette => |i| try response.writer.print(
                                 "\x1b]4;{d};rgb:{x:0>2}/{x:0>2}/{x:0>2}",
                                 .{
                                     i,
@@ -1365,7 +1360,7 @@ pub const StreamHandler = struct {
                                     @as(u16, color.b),
                                 },
                             ),
-                            .dynamic => |dynamic| try writer.print(
+                            .dynamic => |dynamic| try response.writer.print(
                                 "\x1b]{d};rgb:{x:0>2}/{x:0>2}/{x:0>2}",
                                 .{
                                     @intFromEnum(dynamic),
@@ -1380,15 +1375,15 @@ pub const StreamHandler = struct {
                         .none => unreachable,
                     }
 
-                    try writer.writeAll(terminator.string());
+                    try response.writer.writeAll(terminator.string());
                 },
             }
         }
 
-        if (response.items.len > 0) {
+        if (response.writer.end > 0) {
             // If any of the operations were reports, finalize the report
             // string and send it to the terminal.
-            const msg = try termio.Message.writeReq(self.alloc, response.items);
+            const msg = try termio.Message.writeReq(self.alloc, response.writer.buffered());
             self.messageWriter(msg);
         }
     }
diff --git a/src/tripwire.zig b/src/tripwire.zig
index 225674b33..1829c348f 100644
--- a/src/tripwire.zig
+++ b/src/tripwire.zig
@@ -38,7 +38,7 @@
 //!     errdefer allocator.free(buf);
 //!
 //!     try tw.check(.open_file);
-//!     const file = try std.fs.cwd().openFile("foo.txt", .{});
+//!     const file = try std.Io.Dir.cwd().openFile(io, "foo.txt", .{});
 //!     // ...
 //! }
 //!
diff --git a/src/unicode/grapheme.zig b/src/unicode/grapheme.zig
index 73782dd6e..799689357 100644
--- a/src/unicode/grapheme.zig
+++ b/src/unicode/grapheme.zig
@@ -141,22 +141,28 @@ inline fn invalidCodepoint(cp: anytype) bool {
 
 /// This is all the structures and data for the precomputed lookup table
 /// for all possible permutations of state and grapheme break properties.
-/// Precomputation requires 2^13 keys of 4 bit values so the whole table is
-/// 8KB.
+/// Precomputation requires 2^13 keys of byte-sized values so the whole
+/// table is 8KB.
 const Precompute = struct {
     const Key = packed struct(u13) {
         state: uucode.grapheme.BreakState,
-        gb1: uucode.x.types.GraphemeBreakNoControl,
-        gb2: uucode.x.types.GraphemeBreakNoControl,
+        gb1: uucode.types.GraphemeBreakNoControl,
+        gb2: uucode.types.GraphemeBreakNoControl,
 
         fn index(self: Key) usize {
             return @intCast(@as(u13, @bitCast(self)));
         }
     };
 
-    const Value = packed struct(u4) {
+    const Value = packed struct(u8) {
         result: bool,
         state: uucode.grapheme.BreakState,
+
+        /// Explicit padding to give the struct a power-of-two backing
+        /// integer, for the same reason as `Properties._padding` (avoids
+        /// exotic-width LLVM integer accesses that defeat register
+        /// promotion). @sizeOf was already 1, so the table stays 8KB.
+        _padding: u4 = 0,
     };
 
     const data = precompute: {
@@ -171,18 +177,18 @@ const Precompute = struct {
         };
 
         @setEvalBranchQuota(10_000);
-        const info = @typeInfo(uucode.x.types.GraphemeBreakNoControl).@"enum";
+        const info = @typeInfo(uucode.types.GraphemeBreakNoControl).@"enum";
         for (0..max_state_int + 1) |state_int| {
             for (info.fields) |field1| {
                 for (info.fields) |field2| {
                     var state: uucode.grapheme.BreakState = @enumFromInt(state_int);
 
                     const key: Key = .{
-                        .gb1 = @field(uucode.x.types.GraphemeBreakNoControl, field1.name),
-                        .gb2 = @field(uucode.x.types.GraphemeBreakNoControl, field2.name),
+                        .gb1 = @field(uucode.types.GraphemeBreakNoControl, field1.name),
+                        .gb2 = @field(uucode.types.GraphemeBreakNoControl, field2.name),
                         .state = state,
                     };
-                    const v = uucode.x.grapheme.computeGraphemeBreakNoControl(
+                    const v = uucode.grapheme.computeGraphemeBreakNoControl(
                         key.gb1,
                         key.gb2,
                         &state,
diff --git a/src/unicode/props.zig b/src/unicode/props.zig
index 2653f0cc6..dd6a4dbb1 100644
--- a/src/unicode/props.zig
+++ b/src/unicode/props.zig
@@ -7,7 +7,7 @@
 const std = @import("std");
 const uucode = @import("uucode");
 
-pub const Properties = packed struct {
+pub const Properties = packed struct(u16) {
     /// Codepoint width. We clamp to [0, 2] since Ghostty handles control
     /// characters and we max out at 2 for wide characters (i.e. 3-em dash
     /// becomes a 2-em dash).
@@ -18,11 +18,21 @@ pub const Properties = packed struct {
     width_zero_in_grapheme: bool = false,
 
     /// Grapheme break property.
-    grapheme_break: uucode.x.types.GraphemeBreakNoControl = .other,
+    grapheme_break: uucode.types.GraphemeBreakNoControl = .other,
 
     /// Emoji VS compatibility
     emoji_vs_base: bool = false,
 
+    /// Explicit padding to give the struct a power-of-two backing integer.
+    /// This is a performance workaround: with a non-power-of-two backing
+    /// integer (u9), Zig 0.16 lowers loads/stores of this struct through
+    /// mismatched exotic-width LLVM integer types (store i9 / load i16),
+    /// which blocks LLVM from promoting temporaries to registers and forces
+    /// stack round-trips in hot paths like `graphemeBreak`. See
+    /// https://github.com/ziglang/zig/issues/21891 for the upstream issue.
+    /// The size of the lookup table is unchanged (@sizeOf was already 2).
+    _padding: u7 = 0,
+
     // Needed for lut.Generator
     pub fn eql(a: Properties, b: Properties) bool {
         return a.width == b.width and
diff --git a/src/unicode/props_uucode.zig b/src/unicode/props_uucode.zig
index 527a757ed..211d1ac38 100644
--- a/src/unicode/props_uucode.zig
+++ b/src/unicode/props_uucode.zig
@@ -22,10 +22,8 @@ pub fn get(cp: u21) Properties {
 }
 
 /// Runnable binary to generate the lookup tables and output to stdout.
-pub fn main() !void {
-    var arena_state = std.heap.ArenaAllocator.init(std.heap.page_allocator);
-    defer arena_state.deinit();
-    const alloc = arena_state.allocator();
+pub fn main(init: std.process.Init) !void {
+    const alloc = init.arena.allocator();
 
     const gen: lut.Generator(
         Properties,
@@ -48,7 +46,7 @@ pub fn main() !void {
     defer alloc.free(t.stage3);
 
     var buf: [4096]u8 = undefined;
-    var stdout = std.fs.File.stdout().writer(&buf);
+    var stdout = std.Io.File.stdout().writer(init.io, &buf);
     try t.writeZig(&stdout.interface);
     // Use flush instead of end because stdout is a pipe when captured by
     // the build system, and pipes cannot be truncated (Windows returns
diff --git a/src/unicode/symbols_uucode.zig b/src/unicode/symbols_uucode.zig
index 794ca5bab..94344388e 100644
--- a/src/unicode/symbols_uucode.zig
+++ b/src/unicode/symbols_uucode.zig
@@ -3,10 +3,8 @@ const uucode = @import("uucode");
 const lut = @import("lut.zig");
 
 /// Runnable binary to generate the lookup tables and output to stdout.
-pub fn main() !void {
-    var arena_state = std.heap.ArenaAllocator.init(std.heap.page_allocator);
-    defer arena_state.deinit();
-    const alloc = arena_state.allocator();
+pub fn main(init: std.process.Init) !void {
+    const alloc = init.arena.allocator();
 
     const gen: lut.Generator(
         bool,
@@ -32,7 +30,7 @@ pub fn main() !void {
     defer alloc.free(t.stage3);
 
     var buf: [4096]u8 = undefined;
-    var stdout = std.fs.File.stdout().writer(&buf);
+    var stdout = std.Io.File.stdout().writer(init.io, &buf);
     try t.writeZig(&stdout.interface);
     // Use flush instead of end because stdout is a pipe when captured by
     // the build system, and pipes cannot be truncated (Windows returns
diff --git a/test/fuzz-libghostty/src/fuzz_stream.zig b/test/fuzz-libghostty/src/fuzz_stream.zig
index 75c6fd425..4c14086f0 100644
--- a/test/fuzz-libghostty/src/fuzz_stream.zig
+++ b/test/fuzz-libghostty/src/fuzz_stream.zig
@@ -1,3 +1,4 @@
+const builtin = @import("builtin");
 const std = @import("std");
 const ghostty_vt = @import("ghostty-vt");
 const mem = @import("mem.zig");
@@ -24,9 +25,23 @@ pub export fn zig_fuzz_test(
     const alloc = fuzz_alloc.allocator();
     const input = buf[0..len];
 
+    const argv0 = "ghostty-fuzz";
+    const argv0_windows = argv0_windows: {
+        var argv0_windows_buf: [std.unicode.calcUtf16LeLen(argv0) catch unreachable]u16 = undefined;
+        _ = std.unicode.utf8ToUtf16Le(&argv0_windows_buf, argv0) catch unreachable;
+        break :argv0_windows argv0_windows_buf;
+    };
+    var threaded: std.Io.Threaded = .init(alloc, .{
+        .argv0 = .init(.{ .vector = if (builtin.target.os.tag == .windows)
+            &argv0_windows
+        else
+            &.{argv0} }),
+    });
+    defer threaded.deinit();
+
     // Allocate a terminal; if we run out of fixed-buffer space just
     // skip this input (not a bug, just a very large allocation).
-    var t = Terminal.init(alloc, .{
+    var t = Terminal.init(threaded.io(), alloc, .{
         .cols = 80,
         .rows = 24,
         .max_scrollback = 100,