Summary

Add a double Ctrl+C to quit behavior inspired by Codex CLI. Instead of immediately terminating the session when Ctrl+C is pressed on an empty prompt, show a warning message and require a second Ctrl+C press within a timeout window to actually exit.

Current Behavior

Problem: Users can accidentally terminate their session by pressing Ctrl+C once when the prompt is empty. This is frustrating, especially during long conversations or when users instinctively press Ctrl+C to "cancel" even when there's nothing to cancel.

Proposed Behavior

Visual Example

┌─────────────────────────────────────────────────────────┐
│  User presses Ctrl+C on empty prompt                    │
│                                                         │
│  > [empty prompt]                                       │
│                                                         │
│  ⚠️  Press Ctrl+C again to exit (or continue typing)   │
│                                                         │
│  [User presses Ctrl+C again within 1-2 seconds]         │
│  → CLI exits gracefully                                 │
└─────────────────────────────────────────────────────────┘

Implementation Reference

Codex CLI Pattern (Rust)

Codex CLI implements this via a time-bounded arming mechanism:

// Simplified from codex-rs/tui/src/chatwidget.rs
const QUIT_SHORTCUT_TIMEOUT: Duration = Duration::from_secs(1);

fn on_ctrl_c(&mut self) {
    // 1. Try to clear prompt first
    if self.bottom_pane.on_ctrl_c() == CancellationEvent::Handled {
        self.arm_quit_shortcut(key);
        return;
    }

    // 2. Check if shortcut is still armed (within timeout)
    if self.quit_shortcut_active_for(key) {
        self.request_quit_without_confirmation();
        return;
    }

    // 3. Arm the shortcut and show hint
    self.arm_quit_shortcut(key);
    self.bottom_pane.show_quit_shortcut_hint(key);
}

OpenCode Current Implementation

The relevant code is in:

• Signal handling disabled: packages/opencode/src/cli/cmd/tui/app.tsx#L168 (exitOnCtrlC: false)
• Current Ctrl+C logic: packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx#L798-L815

Current logic (simplified):

// If prompt has text → clear it
// If prompt is empty → exit immediately (app_exit)

Suggested Changes

1. Add state to track "quit armed" status and timestamp
2. Modify the empty-prompt Ctrl+C handler:
   • If not armed: arm + show warning message + set timestamp
   • If armed and within timeout: exit
   • If armed but timeout expired: reset and re-arm
3. Add a visible hint in the UI (e.g., status bar or inline message)
4. Suggested timeout: 1-2 seconds (Codex uses 1s)

Benefits

1. Prevents accidental exits - No more losing context from instinctive Ctrl+C
2. Familiar UX - Matches behavior users expect from Codex CLI and other modern CLIs
3. Non-breaking - Users who want to exit just press twice quickly
4. Consistent - Aligns with the existing "double escape to abort" pattern for session interruption

Acceptance Criteria

• Pressing Ctrl+C with text in prompt clears the input (existing behavior)
• Pressing Ctrl+C on empty prompt shows a warning message instead of exiting
• Pressing Ctrl+C again within timeout (1-2s) exits the CLI
• Warning message disappears after timeout or when user starts typing
• Timeout duration is configurable (optional, nice-to-have)

Related

• Codex CLI implementation: https://github.com/openai/codex/blob/main/codex-rs/tui/src/chatwidget.rs#L4017
• OpenCode already uses similar pattern for session abort: double-escape within 5 seconds