feat(tui): optimize performance by caching display lines and token counts, and improve action handling

apps/interfaces/tui/src/run.rs

@@ -76,6 +76,13 @@ fn run_loop(
 }
 
 /// The core single-process render/input loop.
+///
+/// Performance optimizations applied here:
+/// - Skip `terminal.draw()` when `state.dirty == false` (nothing changed)
+/// - Adaptive poll timeout: 50ms when a turn is in-flight (spinner needs
+///   smooth updates), 200ms when idle (no reason to busy-loop)
+/// - Toast expiry is drained once here instead of in two places
+/// - Chat display lines are cached and rebuilt only when content changes
 fn run_loop_inner(
     state: &mut AppStateRest,
     terminal: &mut Terminal<CrosstermBackend<io::Stdout>>,
@@ -84,15 +91,32 @@ fn run_loop_inner(
         if state.quit {
             break;
         }
+
+        // Drain expired toasts exactly once per loop iteration (was being
+        // done here AND in Action::Tick before this fix).
         let now_ms = chrono::Utc::now().timestamp_millis();
         state.misc.drain_expired_toasts(now_ms);
-        terminal.draw(|f| {
-            view::draw(f, state);
-            state.dirty = false;
-        })?;
 
-        // Poll terminal with 50 ms timeout
-        if crossterm::event::poll(Duration::from_millis(50))? {
+        // Skip render when nothing has changed — avoids expensive markdown
+        // re-parse and layout recalculation every cycle while idle.
+        if state.dirty {
+            // Pre-warm display caches before entering the terminal.draw closure.
+            // This lets view::draw work with &AppStateRest (no mutation inside draw).
+            view::pre_render(state);
+            terminal.draw(|f| {
+                view::draw(f, state);
+                state.dirty = false;
+            })?;
+        }
+
+        // Adaptive poll: fast when animating, slow when idle.
+        let poll_timeout = if state.turn_in_flight() {
+            Duration::from_millis(50)   // smooth spinner @ ~20fps
+        } else {
+            Duration::from_millis(200)  // idle: 5fps, saves CPU
+        };
+
+        if crossterm::event::poll(poll_timeout)? {
             match crossterm::event::read()? {
                 Event::Key(key) => {
                     if key.kind == KeyEventKind::Press || key.kind == KeyEventKind::Repeat {