macos: update AGENTS.md

AGENTS.md

@@ -18,13 +18,6 @@ A file for [guiding coding agents](https://agents.md/).
 - macOS app: `macos/`
 - GTK (Linux and FreeBSD) app: `src/apprt/gtk`
 
-## macOS App
-
-- Do not use `xcodebuild`
-- Use `zig build` to build the macOS app and any shared Zig code
-- Use `zig build run` to build and run the macOS app
-- Run Xcode tests using `zig build test`
-
 ## Issue and PR Guidelines
 
 - Never create an issue.

macos/AGENTS.md

@@ -1,3 +1,9 @@
 # macOS Ghostty Application
 
 - Use `swiftlint` for formatting and linting Swift code.
+- If code outside of this directory is modified, use
+  `zig build -Demit-macos-app=false` before building the macOS app to update
+  the underlying Ghostty library.
+- Use `xcodebuild` to build the macOS app, do not use `zig build`
+  (except to build the underlying library as mentioned above).
+- Run unit tests directly with `xcodebuild`