fix(cli): prevent terminal escape sequences from leaking on exit by mattKorwel · Pull Request #22682 · google-gemini/gemini-cli

mattKorwel · 2026-03-16T17:17:42Z

Summary

This PR prevents terminal escape sequences (especially mouse tracking events) from leaking into the shell prompt after the Gemini CLI exits.

Details

Reordered runExitCleanup: Updated the cleanup sequence in packages/cli/src/utils/cleanup.ts to execute cleanupFunctions (which disable terminal modes and unmount the UI) before draining stdin. This ensures "in-flight" terminal sequences are cleared while the terminal is still in raw mode.
Increased Drain Timeout: Increased the drainStdin timeout from 50ms to 100ms for better reliability on slower terminals or during high-activity sessions.
Enhanced Synchronous Cleanup: Updated TERMINAL_CLEANUP_SEQUENCE in packages/cli/src/ui/utils/terminalCapabilityManager.ts to include mouse tracking disable sequences. This provides a fallback if the process exits hard without running the full cleanup.
Added Verification Test: Added a test case in packages/cli/src/utils/cleanup.test.ts to verify the execution order of cleanup functions relative to stdin draining.

Related Issues

Fixes #16801 (Partial)
Related to mouse/terminal stability issues in alternate buffer mode.

How to Validate

Enable alternate buffer in settings.
Start an interactive session.
Move the mouse vigorously or scroll rapidly while typing /exit or /quit.
Verify that no escape sequences (e.g., ^[[<65;...) appear in the shell prompt after exit.
Run tests: npm test -w @google/gemini-cli -- src/utils/cleanup.test.ts

Pre-Merge Checklist

Reorders cleanup sequence to disable terminal modes before draining stdin and increases drain timeout. Also adds fallback mouse tracking disable to synchronous cleanup.

gemini-code-assist · 2026-03-16T17:17:58Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses an issue where terminal escape sequences could leak into the shell prompt after the CLI exits, leading to a messy or unresponsive terminal. The changes improve terminal stability and user experience by refining the exit cleanup process, ensuring all terminal modes are properly reset and input buffers are cleared before the application fully terminates.

Highlights

Cleanup Order Reversal: The runExitCleanup sequence was reordered to execute asynchronous cleanup functions (which disable terminal modes and unmount the UI) before draining stdin. This ensures terminal sequences are cleared while the terminal is still in raw mode, preventing leaks.
Increased Stdin Drain Timeout: The drainStdin timeout was increased from 50ms to 100ms to improve reliability, especially on slower terminals or during high-activity sessions.
Enhanced Synchronous Cleanup: The TERMINAL_CLEANUP_SEQUENCE was updated to include additional mouse tracking disable sequences, providing a more robust fallback for scenarios where the process exits abruptly without full cleanup.
New Test Case: A new test case was added to verify the precise execution order of cleanup functions relative to stdin draining, ensuring the intended cleanup flow is maintained.

Changelog

packages/cli/src/ui/utils/terminalCapabilityManager.ts
- Imported disableMouseEvents from @google/gemini-cli-core.
- Updated TERMINAL_CLEANUP_SEQUENCE to include additional escape codes for disabling mouse events.
- Added a call to disableMouseEvents() within cleanupTerminalOnExit.
packages/cli/src/utils/cleanup.test.ts
- Added a new test case to assert the execution order of cleanupFunctions, drainStdin, and runSyncCleanup.
packages/cli/src/utils/cleanup.ts
- Reordered the runExitCleanup function to execute cleanupFunctions before drainStdin and runSyncCleanup.
- Increased the drainStdin timeout from 50ms to 100ms.

Activity

The author has completed the 'Added/updated tests' checklist item.
The author has validated the changes on MacOS using 'npm run'.

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Code Review

This pull request correctly addresses an issue where terminal escape sequences could leak on exit by reordering the cleanup operations. Running the async cleanup (including UI unmounting) before draining stdin and disabling raw mode is the right approach. The addition of more comprehensive escape sequences for hard exits is also a good defensive measure. I've found one issue in the new test case where the assertion for the cleanup order seems to be incorrect, which I've detailed in a comment.

packages/cli/src/utils/cleanup.test.ts

github-actions · 2026-03-16T17:21:52Z

Size Change: +86 B (0%)

Total Size: 26.1 MB

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mattKorwel · 2026-03-16T21:46:33Z

jacob314 · 2026-03-17T16:21:23Z

Great to see this fixed. Others had tried and failed to fix this. Nit: did you reference the wrong issue? #1680 seems unrelated

Impressively Gemini fixed this as part of the code review noting that you meant issue #16801

jacob314

Looks great! This is a solid fix for the escape sequences leaking on exit. The reordering of the cleanup sequence and the added mouse disabling sequences to the fallback are very robust.

One minor note: in packages/cli/src/utils/cleanup.ts and the PR description, you reference issue #1680, but the correct issue number for the garbage on exit bug is #16801. Could you update the PR description and the code comment?

Otherwise, the changes look excellent and the test successfully validates the cleanup order.

jacob314 · 2026-03-17T19:13:51Z

packages/cli/src/ui/utils/terminalCapabilityManager.ts

  disableKittyKeyboardProtocol();
  disableModifyOtherKeys();
  disableBracketedPasteMode();
+  disableMouseEvents();


disableMouseEvents is getting called from AppContainer. that is likely not needed if we are doing it here.
as a follow up we should also track whether we have called enableMouseEvents and make disableMouseEvents a no-op if we have not enabled it. unless you are in alternate buffer mode we have not enabled mouse events.

packages/cli/src/utils/cleanup.ts

jacob314

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

fix(cli): prevent terminal escape sequences from leaking on exit

7481b9d

Reorders cleanup sequence to disable terminal modes before draining stdin and increases drain timeout. Also adds fallback mouse tracking disable to synchronous cleanup.

mattKorwel requested a review from a team as a code owner March 16, 2026 17:17

gemini-code-assist bot reviewed Mar 16, 2026

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packages/cli/src/utils/cleanup.test.ts Outdated Show resolved Hide resolved

gemini-cli bot added the priority/p3 Backlog - a good idea but not currently a priority. label Mar 16, 2026

mattKorwel self-assigned this Mar 16, 2026

mattKorwel added the area/core Issues related to User Interface, OS Support, Core Functionality label Mar 16, 2026

Merge branch 'main' into mk-odd-keyoutput

1264ed7

jacob314 approved these changes Mar 17, 2026

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jacob314 reviewed Mar 17, 2026

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jacob314 reviewed Mar 17, 2026

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jacob314 approved these changes Mar 17, 2026

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mattKorwel added this pull request to the merge queue Mar 20, 2026

mattKorwel removed this pull request from the merge queue due to a manual request Mar 20, 2026

mattKorwel and others added 3 commits March 19, 2026 23:32

Update packages/cli/src/utils/cleanup.test.ts

6160263

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Update packages/cli/src/utils/cleanup.ts

24fad2e

Merge branch 'main' into mk-odd-keyoutput

2ea4c11

mattKorwel enabled auto-merge March 20, 2026 06:34

chore(cli): correct issue number in cleanup code and PR

046b33c

gemini-cli bot added the 🔒 maintainer only ⛔ Do not contribute. Internal roadmap item. label Mar 23, 2026

test(cli): fix cleanup order and call count in tests

a9d8989

mattKorwel added this pull request to the merge queue Mar 23, 2026

Merged via the queue into main with commit b58d79c Mar 23, 2026
27 checks passed

mattKorwel deleted the mk-odd-keyoutput branch March 23, 2026 18:16

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fix(cli): prevent terminal escape sequences from leaking on exit#22682

fix(cli): prevent terminal escape sequences from leaking on exit#22682
mattKorwel merged 7 commits intomainfrom
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