cleanup by just scrolling in the renderer

src/Surface.zig

@@ -1070,12 +1070,6 @@ pub fn handleMessage(self: *Surface, msg: Message) !void {
 
         .scrollbar => |scrollbar| self.updateScrollbar(scrollbar),
 
-        .scroll_to_bottom => {
-            self.queueIo(.{
-                .scroll_viewport = .{ .bottom = {} },
-            }, .unlocked);
-        },
-
         .present_surface => try self.presentSurface(),
 
         .password_input => |v| try self.passwordInput(v),
@@ -1180,7 +1174,7 @@ fn selectionScrollTick(self: *Surface) !void {
     }
 
     // Scroll the viewport as required
-    try t.scrollViewport(.{ .delta = delta });
+    t.scrollViewport(.{ .delta = delta });
 
     // Next, trigger our drag behavior
     const pin = t.screens.active.pages.pin(.{
@@ -2785,7 +2779,7 @@ pub fn keyCallback(
             try self.setSelection(null);
         }
 
-        if (self.config.scroll_to_bottom.keystroke) try self.io.terminal.scrollViewport(.bottom);
+        if (self.config.scroll_to_bottom.keystroke) self.io.terminal.scrollViewport(.bottom);
 
         try self.queueRender();
     }
@@ -3538,7 +3532,7 @@ pub fn scrollCallback(
             // Modify our viewport, this requires a lock since it affects
             // rendering. We have to switch signs here because our delta
             // is negative down but our viewport is positive down.
-            try self.io.terminal.scrollViewport(.{ .delta = y.delta * -1 });
+            self.io.terminal.scrollViewport(.{ .delta = y.delta * -1 });
         }
     }
 
@@ -5069,7 +5063,7 @@ pub fn posToViewport(self: Surface, xpos: f64, ypos: f64) terminal.point.Coordin
 ///
 /// Precondition: the render_state mutex must be held.
 fn scrollToBottom(self: *Surface) !void {
-    try self.io.terminal.scrollViewport(.{ .bottom = {} });
+    self.io.terminal.scrollViewport(.{ .bottom = {} });
     try self.queueRender();
 }
 

src/apprt/surface.zig

@@ -108,10 +108,6 @@ pub const Message = union(enum) {
     /// Selected search index change
     search_selected: ?usize,
 
-    /// Scroll the viewport to the bottom. This is triggered by the renderer
-    /// when new output is detected and scroll-to-bottom on output is enabled.
-    scroll_to_bottom,
-
     pub const ReportTitleStyle = enum {
         csi_21_t,
 

src/renderer/generic.zig

@@ -128,7 +128,7 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
         /// Tracks the last bottom-right pin of the screen to detect new output.
         /// When the final line changes (node or y differs), new content was added.
         /// Used for scroll-to-bottom on output feature.
-        last_bottom_node: ?*terminal.PageList.List.Node,
+        last_bottom_node: ?usize,
         last_bottom_y: terminal.size.CellCountInt,
 
         /// The most recent viewport matches so that we can render search
@@ -1176,6 +1176,26 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
                     return;
                 }
 
+                // If scroll-to-bottom on output is enabled, check if the final line
+                // changed by comparing the bottom-right pin. If the node pointer or
+                // y offset changed, new content was added to the screen.
+                // Update this BEFORE we update our render state so we can
+                // draw the new scrolled data immediately.
+                if (self.config.scroll_to_bottom_on_output) scroll: {
+                    const br = state.terminal.screens.active.pages.getBottomRight(.screen) orelse break :scroll;
+
+                    // If the pin hasn't changed, then don't scroll.
+                    if (self.last_bottom_node == @intFromPtr(br.node) and
+                        self.last_bottom_y == br.y) break :scroll;
+
+                    // Update tracked pin state for next frame
+                    self.last_bottom_node = @intFromPtr(br.node);
+                    self.last_bottom_y = br.y;
+
+                    // Scroll
+                    state.terminal.scrollViewport(.bottom);
+                }
+
                 // Update our terminal state
                 try self.terminal_state.update(self.alloc, state.terminal);
 
@@ -1192,25 +1212,6 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
                 // cross-thread mailbox message within the IO path.
                 const scrollbar = state.terminal.screens.active.pages.scrollbar();
 
-                // If scroll-to-bottom on output is enabled, check if the final line
-                // changed by comparing the bottom-right pin. If the node pointer or
-                // y offset changed, new content was added to the screen.
-                if (self.config.scroll_to_bottom_on_output) {
-                    const bottom_right = state.terminal.screens.active.pages.getBottomRight(.screen);
-                    if (bottom_right) |br| {
-                        const pin_changed = (self.last_bottom_node != br.node) or
-                            (self.last_bottom_y != br.y);
-
-                        if (pin_changed and !state.terminal.screens.active.viewportIsBottom()) {
-                            _ = self.surface_mailbox.push(.scroll_to_bottom, .instant);
-                        }
-
-                        // Update tracked pin state for next frame
-                        self.last_bottom_node = br.node;
-                        self.last_bottom_y = br.y;
-                    }
-                }
-
                 // Get our preedit state
                 const preedit: ?renderer.State.Preedit = preedit: {
                     const p = state.preedit orelse break :preedit null;

src/terminal/Terminal.zig

@@ -1625,7 +1625,7 @@ pub const ScrollViewport = union(enum) {
 };
 
 /// Scroll the viewport of the terminal grid.
-pub fn scrollViewport(self: *Terminal, behavior: ScrollViewport) !void {
+pub fn scrollViewport(self: *Terminal, behavior: ScrollViewport) void {
     self.screens.active.scroll(switch (behavior) {
         .top => .{ .top = {} },
         .bottom => .{ .active = {} },

src/termio/Termio.zig

@@ -641,10 +641,13 @@ pub fn clearScreen(self: *Termio, td: *ThreadData, history: bool) !void {
 }
 
 /// Scroll the viewport
-pub fn scrollViewport(self: *Termio, scroll: terminalpkg.Terminal.ScrollViewport) !void {
+pub fn scrollViewport(
+    self: *Termio,
+    scroll: terminalpkg.Terminal.ScrollViewport,
+) void {
     self.renderer_state.mutex.lock();
     defer self.renderer_state.mutex.unlock();
-    try self.terminal.scrollViewport(scroll);
+    self.terminal.scrollViewport(scroll);
 }
 
 /// Jump the viewport to the prompt.

src/termio/Thread.zig

@@ -321,7 +321,7 @@ fn drainMailbox(
             .resize => |v| self.handleResize(cb, v),
             .size_report => |v| try io.sizeReport(data, v),
             .clear_screen => |v| try io.clearScreen(data, v.history),
-            .scroll_viewport => |v| try io.scrollViewport(v),
+            .scroll_viewport => |v| io.scrollViewport(v),
             .selection_scroll => |v| {
                 if (v) {
                     self.startScrollTimer(cb);

src/termio/stream_handler.zig

@@ -232,7 +232,7 @@ pub const StreamHandler = struct {
             .erase_display_below => self.terminal.eraseDisplay(.below, value),
             .erase_display_above => self.terminal.eraseDisplay(.above, value),
             .erase_display_complete => {
-                try self.terminal.scrollViewport(.{ .bottom = {} });
+                self.terminal.scrollViewport(.{ .bottom = {} });
                 self.terminal.eraseDisplay(.complete, value);
             },
             .erase_display_scrollback => self.terminal.eraseDisplay(.scrollback, value),