hide CoT by default; show headers in status indicator (#2316)

Plan is for full CoT summaries to be visible in a "transcript view" when
we implement that, but for now they're hidden.


https://github.com/user-attachments/assets/e8a1b0ef-8f2a-48ff-9625-9c3c67d92cdb

codex-rs/tui/src/status_indicator_widget.rs

@@ -30,6 +30,8 @@ pub(crate) struct StatusIndicatorWidget {
     /// Latest text to display (truncated to the available width at render
     /// time).
     text: String,
+    /// Animated header text (defaults to "Working").
+    header: String,
 
     /// Animation state: reveal target `text` progressively like a typewriter.
     /// We compute the currently visible prefix length based on the current
@@ -47,6 +49,7 @@ impl StatusIndicatorWidget {
     pub(crate) fn new(app_event_tx: AppEventSender, frame_requester: FrameRequester) -> Self {
         Self {
             text: String::from("waiting for model"),
+            header: String::from("Working"),
             last_target_len: 0,
             base_frame: 0,
             reveal_len_at_base: 0,
@@ -95,6 +98,13 @@ impl StatusIndicatorWidget {
         self.app_event_tx.send(AppEvent::CodexOp(Op::Interrupt));
     }
 
+    /// Update the animated header label (left of the brackets).
+    pub(crate) fn update_header(&mut self, header: String) {
+        if self.header != header {
+            self.header = header;
+        }
+    }
+
     /// Reset the animation and start revealing `text` from the beginning.
     #[cfg(test)]
     pub(crate) fn restart_with_text(&mut self, text: String) {
@@ -147,12 +157,12 @@ impl WidgetRef for StatusIndicatorWidget {
 
         // Schedule next animation frame.
         self.frame_requester
-            .schedule_frame_in(Duration::from_millis(100));
+            .schedule_frame_in(Duration::from_millis(32));
         let idx = self.current_frame();
         let elapsed = self.start_time.elapsed().as_secs();
         let shown_now = self.current_shown_len(idx);
         let status_prefix: String = self.text.chars().take(shown_now).collect();
-        let animated_spans = shimmer_spans("Working");
+        let animated_spans = shimmer_spans(&self.header);
 
         // Plain rendering: no borders or padding so the live cell is visually indistinguishable from terminal scrollback.
         let inner_width = area.width as usize;