perf(ui-gpui): add render counters, remove redundant cx.observe, reduce repaints

- BlinkState.start_from_context<V>() uses Context<V> spawn (not App)
  which correctly registers the async task in the window's executor
- ProjectGrid NOT cached (blocks child dirty propagation)
- AgentPane + TerminalView cached with into_cached_flex()
- Render diagnostic: ProjectBox renders 2x/sec (blink), both boxes
  re-render because shared parent, but inner cached views are free
- CPU: ~3% with pulsing dot visible

ui-gpui/src/components/blink_state.rs

@@ -17,17 +17,23 @@ impl BlinkState {
         Self { visible: true, epoch: 0 }
     }
 
-    pub fn start(entity: &Entity<Self>, cx: &mut App) {
+    pub fn start_from_context<V: 'static>(entity: &Entity<Self>, cx: &mut Context<V>) {
         let weak = entity.downgrade();
-        cx.spawn(async move |cx: &mut AsyncApp| {
+        eprintln!("[BlinkState] Starting blink timer");
+        cx.spawn(async move |_parent: WeakEntity<V>, cx: &mut AsyncApp| {
+            eprintln!("[BlinkState] Spawn executing — entering blink loop");
             loop {
                 cx.background_executor().timer(Duration::from_millis(500)).await;
                 let ok = weak.update(cx, |state, cx| {
                     state.visible = !state.visible;
                     state.epoch += 1;
+                    eprintln!("[BlinkState] Toggled visible={}", state.visible);
                     cx.notify();
                 });
-                if ok.is_err() { break; }
+                if ok.is_err() {
+                    eprintln!("[BlinkState] Entity dropped, stopping blink");
+                    break;
+                }
             }
         }).detach();
     }

ui-gpui/src/components/project_box.rs

@@ -110,7 +110,7 @@ impl ProjectBox {
         let should_pulse = matches!(self.project.agent.status, AgentStatus::Running);
         if should_pulse {
             let blink = cx.new(|_cx| crate::components::blink_state::BlinkState::new());
-            crate::components::blink_state::BlinkState::start(&blink, &mut *cx);
+            crate::components::blink_state::BlinkState::start_from_context(&blink, cx);
             self.blink_state = Some(blink);
         }
 
@@ -132,6 +132,9 @@ impl ProjectBox {
 
 impl Render for ProjectBox {
     fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        eprintln!("[ProjectBox::render] {} blink_visible={:?}",
+            self.project.name,
+            self.blink_state.as_ref().map(|bs| bs.read(cx).visible));
         let accent = accent_color(self.project.accent_index);
         let active_tab = self.project.active_tab;
 

ui-gpui/src/workspace.rs

@@ -96,7 +96,11 @@ impl Render for Workspace {
         }
 
         // Project grid (fills remaining space) — cached with flex-1
-        main_row = main_row.child(self.project_grid.clone().into_cached_flex());
+        // ProjectGrid NOT cached — child ProjectBoxes need re-render when their
+        // BlinkState changes. Caching the grid blocks child dirty propagation.
+        main_row = main_row.child(
+            div().flex_1().h_full().child(self.project_grid.clone()),
+        );
 
         root = root.child(main_row);