fix(tui): disable double-press quit shortcut (#9220)

Disables the default Ctrl+C/Ctrl+D double-press quit UX (keeps the code
path behind a const) while we rethink the quit/interrupt flow.

Tests:
- just fmt
- cargo clippy --fix --all-features --tests --allow-dirty --allow-no-vcs
-p codex-tui
- cargo test -p codex-tui --lib

codex-rs/tui/src/bottom_pane/mod.rs

@@ -71,6 +71,13 @@ pub(crate) use feedback_view::FeedbackNoteView;
 /// Keeping a single value ensures Ctrl+C and Ctrl+D behave identically.
 pub(crate) const QUIT_SHORTCUT_TIMEOUT: Duration = Duration::from_secs(1);
 
+/// Whether Ctrl+C/Ctrl+D require a second press to quit.
+///
+/// This UX experiment was enabled by default, but requiring a double press to quit feels janky in
+/// practice (especially for users accustomed to shells and other TUIs). Disable it for now while we
+/// rethink a better quit/interrupt design.
+pub(crate) const DOUBLE_PRESS_QUIT_SHORTCUT_ENABLED: bool = false;
+
 /// The result of offering a cancellation key to a bottom-pane surface.
 ///
 /// This is primarily used for Ctrl+C routing: active views can consume the key to dismiss
@@ -359,6 +366,10 @@ impl BottomPane {
     /// after [`QUIT_SHORTCUT_TIMEOUT`] so the hint disappears even if the user
     /// stops typing and no other events trigger a draw.
     pub(crate) fn show_quit_shortcut_hint(&mut self, key: KeyBinding) {
+        if !DOUBLE_PRESS_QUIT_SHORTCUT_ENABLED {
+            return;
+        }
+
         self.composer
             .show_quit_shortcut_hint(key, self.has_input_focus);
         let frame_requester = self.frame_requester.clone();
@@ -695,7 +706,7 @@ mod tests {
     }
 
     #[test]
-    fn ctrl_c_on_modal_consumes_and_shows_quit_hint() {
+    fn ctrl_c_on_modal_consumes_without_showing_quit_hint() {
         let (tx_raw, _rx) = unbounded_channel::<AppEvent>();
         let tx = AppEventSender::new(tx_raw);
         let features = Features::with_defaults();
@@ -711,7 +722,7 @@ mod tests {
         });
         pane.push_approval_request(exec_request(), &features);
         assert_eq!(CancellationEvent::Handled, pane.on_ctrl_c());
-        assert!(pane.quit_shortcut_hint_visible());
+        assert!(!pane.quit_shortcut_hint_visible());
         assert_eq!(CancellationEvent::NotHandled, pane.on_ctrl_c());
     }