fix(ui): Ctrl-C aborts; double-tap exits regardless of state

Before: a single Ctrl-C while the agent was busy aborted the turn but
never armed the exit window, so users had no fast way out during a
long generation. They had to wait for the abort to complete, land in
idle, then press Ctrl-C twice. Frustrating when you want to bail.

Now: every Ctrl-C arms a 1s double-tap window. While busy, the first
press also aborts (silent — the abort is its own feedback). While
idle, the first press shows the 'press again to exit' hint. The
second press within 1s exits in either case. 'Twice real fast = quit'
is the standard CLI convention.

Author: halfaipg

src/ui/App.tsx

@@ -347,25 +347,34 @@ function ChatApp({ bundle, onExit }: ChatAppProps) {
 		}
 	};
 
-	// Double-tap-to-exit: first Ctrl-C when idle posts a hint, second
-	// within 2s actually exits. While busy, Ctrl-C cancels the turn (one
-	// press) — the user already meant to interrupt and shouldn't have
-	// to confirm. The hint is a status line that times out on its own
-	// so the user doesn't end up with a stale message stuck below.
+	// Ctrl-C semantics:
+	//   • While the agent is busy: abort the turn. Stays in the app.
+	//   • A second Ctrl-C within DOUBLE_TAP_MS exits, regardless of
+	//     whether the previous press aborted or just landed a hint.
+	//     "Twice real fast" is universally understood as "I want out."
+	//   • While idle: first press posts a hint + arms the exit window.
+	//
+	// 1000ms is "real fast" — wide enough that intentional double-taps
+	// register, tight enough that mashing Ctrl-C twice while flustered
+	// doesn't accidentally exit. Tunable here if testers want it longer.
 	const exitTimerRef = useMemo(() => ({ deadline: 0 }), []);
 	const handleAbort = () => {
-		if (busy) {
-			bundle.agent.abort();
-			dispatch({ type: "abort" });
-			return;
-		}
+		const DOUBLE_TAP_MS = 1000;
 		const now = Date.now();
 		if (now < exitTimerRef.deadline) {
 			onExit();
 			return;
 		}
-		exitTimerRef.deadline = now + 2000;
-		appendStatus("Press Ctrl-C again within 2s to exit.");
+		exitTimerRef.deadline = now + DOUBLE_TAP_MS;
+		if (busy) {
+			bundle.agent.abort();
+			dispatch({ type: "abort" });
+			// No hint here — the abort itself is the feedback. The
+			// exit window is set silently so a quick second tap still
+			// gets the user out without confirmation theater.
+			return;
+		}
+		appendStatus("Press Ctrl-C again to exit.");
 	};
 
 	return (

src/ui/Input.tsx

@@ -82,7 +82,7 @@ function pickPlaceholder(hasHistory: boolean): string {
  *   Ctrl-W          kill word before cursor
  *   Ctrl-Y          yank (paste from kill ring)
  *   Ctrl-Z          undo
- *   Ctrl-C          abort (busy → cancel turn, idle → exit app)
+ *   Ctrl-C          busy → cancel turn (stay in app); double-tap → exit
  */
 export function Input({ disabled, onSubmit, onAbort, commands, history, cwd }: InputProps) {
 	const [state, setState] = useState(initialInputState());