feat: allow esc to interrupt session (openai#2054)

## Summary
- allow Esc to interrupt the current session when a task is running
- document Esc as an interrupt key in status indicator

## Testing
- `just fmt`
- `just fix` *(fails: E0658 `let` expressions in this position are
unstable)*
- `cargo test --all-features` *(fails: E0658 `let` expressions in this
position are unstable)*

------
https://chatgpt.com/codex/tasks/task_i_689698cf605883208f57b0317ff6a303

Author: pakrym-oai

codex-rs/tui/src/app.rs

@@ -236,6 +236,20 @@ impl App<'_> {
                                 self.app_event_tx.send(AppEvent::ExitRequest);
                             }
                         },
+                        KeyEvent {
+                            code: KeyCode::Esc,
+                            kind: KeyEventKind::Press,
+                            ..
+                        } => match &mut self.app_state {
+                            AppState::Chat { widget } => {
+                                if !widget.on_esc() {
+                                    self.dispatch_key_event(key_event);
+                                }
+                            }
+                            AppState::Onboarding { .. } => {
+                                self.dispatch_key_event(key_event);
+                            }
+                        },
                         KeyEvent {
                             code: KeyCode::Char('z'),
                             modifiers: crossterm::event::KeyModifiers::CONTROL,

codex-rs/tui/src/chatwidget.rs

@@ -571,6 +571,14 @@ impl ChatWidget<'_> {
         self.bottom_pane.on_file_search_result(query, matches);
     }
 
+    pub(crate) fn on_esc(&mut self) -> bool {
+        if self.bottom_pane.is_task_running() {
+            self.interrupt_running_task();
+            return true;
+        }
+        false
+    }
+
     /// Handle Ctrl-C key press.
     /// Returns CancellationEvent::Handled if the event was consumed by the UI, or
     /// CancellationEvent::Ignored if the caller should handle it (e.g. exit).

codex-rs/tui/src/status_indicator_widget.rs

@@ -231,14 +231,14 @@ impl WidgetRef for StatusIndicatorWidget {
         spans.extend(animated_spans);
         // Space between header and bracket block
         spans.push(Span::raw(" "));
-        // Non-animated, dim bracket content, with only "Ctrl c" bold
+        // Non-animated, dim bracket content, with keys bold
         let bracket_prefix = format!("({elapsed}s • ");
         spans.push(Span::styled(
             bracket_prefix,
             Style::default().fg(Color::Gray).add_modifier(Modifier::DIM),
         ));
         spans.push(Span::styled(
-            "Ctrl C",
+            "Esc",
             Style::default()
                 .fg(Color::Gray)
                 .add_modifier(Modifier::DIM | Modifier::BOLD),