What happened?

While reviewing the non-interactive Ctrl+C cancellation path, I noticed that setupStdinCancellation() enables raw mode whenever process.stdin.isTTY is true, but the raw mode restoration only happens through the normal finally cleanup path.

The affected paths are:

• packages/cli/src/nonInteractiveCli.ts
• packages/cli/src/nonInteractiveCliAgentSession.ts

That means if the process exits abruptly after process.stdin.setRawMode(true) succeeds but before cleanupStdinCancellation() runs normally, the user’s terminal can be left in raw mode. In that state, the terminal feels broken until the user runs something like reset or stty sane.

Small nuance: SIGKILL itself cannot be handled by Node, so this cannot protect against literal kill -9. But registering the stdin cleanup on process.on('exit', ...) gives a best-effort fallback for normal Node process exits after raw mode has been enabled.

What did you expect to happen?

Once non-interactive mode enables stdin raw mode, Gemini CLI should register a synchronous, idempotent cleanup path immediately so raw mode is restored on process exit as well as on the normal finally path.

Expected behavior:

• Save the original raw-mode state before enabling raw mode.
• Restore that state during normal cleanup.
• Also restore that state from a process.on('exit', cleanupStdinCancellation) handler.
• Remove only the keypress listener registered by this code path, rather than clearing all keypress listeners on stdin.

Steps to reproduce

This is easiest to verify with a regression test rather than a manual terminal repro, because leaving a real terminal in raw mode is annoying.

Code path:

1. Run Gemini CLI in non-interactive mode with TTY stdin.
2. setupStdinCancellation() calls process.stdin.setRawMode(true).
3. Simulate process exit before the normal finally cleanup path completes.
4. Observe that the previous implementation had no process.on('exit', ...) handler to restore raw mode.

A regression test can assert that:

• an exit handler is registered,
• raw mode is enabled,
• invoking the exit handler restores the previous raw-mode state,
• the handler unregisters itself afterward.

Client information

Not specific to a model, auth provider, or Gemini API response.

Platform observed during development:

• macOS
• Node.js 20+
• Gemini CLI local checkout

This bug is in local terminal/stdin lifecycle handling, so it can affect any login mode.

Login information

Not login-specific.

This happens before the auth/model path matters and applies equally to Google account, API key, or Vertex AI usage.

Anything else we need to know?

I have a small fix and regression coverage ready.

The fix registers cleanupStdinCancellation with process.on('exit', ...) in both non-interactive implementations and makes the cleanup idempotent. It also removes only the owned keypress listener instead of calling removeAllListeners('keypress').

Targeted verification passed locally:

<img width="936" height="582" alt="Image" src="https://github.com/user-attachments/assets/9d1400c3-b920-4549-a556-6a5321f060dc" />