fix: restore AskUser answers after Ctrl+Z + fg suspend/resume

[PrafulVRaj]

Summary

Fix loss of in-progress AskUser answers when the user suspends gemini-cli with Ctrl+Z and resumes with fg. Answers typed before suspension are now fully restored on resume.

Details

A way for AskUserDialog to register a function that returns its current answers. AppContainer stores those answers before suspension using onBeforeSuspend. When the dialog mounts again, it initializes its reducer with the saved answers. New methods were added to UIActionsContext: savedAskUserAnswers, registerAskUserAnswers, unregisterAskUserAnswers. useSuspend now supports an optional onBeforeSuspend callback.

It achieves pressing Ctrl+Z no longer resets AskUser dialog inputs, answers are saved before suspend and restored after resume. Dialog still owns its state (no unnecessary global state lifting) and clean separation of concerns using context + refs.

Related Issues

Fixes #20838

How to Validate

Windows:

1. Run gemini CLI
2. Trigger an AskUser dialog
3. Press Ctrl+Z
4. Verify warning appears: "Ctrl+Z suspend is not supported on Windows."
5. Verify the dialog and typed text are unaffected ✓

macOS / Linux:
same as win but some difference

1. Press Ctrl+Z once — verify warning: "Press Ctrl+Z again to suspend"
2. Press Ctrl+Z again — CLI suspends, shell prompt returns
3. Run fg to resume
4. Verify your typed answer is fully restored ✓

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[gemini-code-assist]

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 a critical bug in the gemini-cli where in-progress user answers in AskUserDialog were lost after suspending the application with Ctrl+Z and then resuming it. The fix ensures that user input is fully restored upon resuming the CLI, significantly improving the user experience for interactive prompts by preventing unexpected data loss.

Highlights

• State Preservation: Implemented a mechanism to preserve user-typed answers in AskUserDialog after suspending and resuming the gemini-cli application.
• Signal Handling: Added SIGTSTP and SIGCONT signal handlers to manage application suspension and resume events, specifically for non-Windows platforms.
• Component Re-keying: Utilized a resumeKey to force re-mounting of TextQuestionView and ChoiceQuestionView components upon resume, preventing loss of their internal state.

Changelog

• packages/cli/src/ui/components/AskUserDialog.tsx
  • Imported the useState React hook.
  • Introduced a resumeKey state variable initialized to 0.
  • Added a useEffect hook to register signal handlers for SIGTSTP and SIGCONT.
  • Implemented logic to increment resumeKey when a SIGCONT signal is received, indicating a resume from suspension.
  • Updated the key prop for TextQuestionView and ChoiceQuestionView components to include the resumeKey, forcing a re-render and state restoration upon resume.

Activity

• The author has updated tests to reflect the changes.
• No breaking changes were noted by the author.
• Validation has been performed on Windows, MacOS, and Linux using npm run and npx.

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[gemini-code-assist]

Code Review

The pull request effectively addresses the issue of losing in-progress AskUser answers when the CLI is suspended and resumed. By introducing a resumeKey that increments on SIGCONT and using it in the key prop of TextQuestionView and ChoiceQuestionView, the components are correctly remounted, ensuring their internal state is re-initialized with the preserved answers. The use of useEffect for signal handling and useState for the key is a standard and appropriate React pattern for this scenario. The solution is well-implemented and directly resolves the problem described.

[jackwotherspoon]

Closing to allow other PR created before this to fix the issue 👍