Fix: Avoid tool confirmation timeout when no UI listeners are present

[pdHaku0]

Summary

Fixes an issue where tool execution hangs waiting for user confirmation in environments without an attached UI listener (e.g., initial ACP connection or headless mode).

Details

In packages/core/src/confirmation-bus/message-bus.ts, the ASK_USER policy decision logic has been updated.
It now checks if there are any active listeners for TOOL_CONFIRMATION_REQUEST.

• If listeners exist: The request is emitted as usual.
• If NO listeners exist: It immediately emits a TOOL_CONFIRMATION_RESPONSE with confirmed: false.

This prevents the system from waiting indefinitely (or until a long timeout) for a user confirmation that effectively cannot be given, improving responsiveness in automated or headless scenarios.

Related Issues

Fixes #17952

How to Validate

1. Run the Gemini CLI in a headless mode or initiate an ACP connection without an interactive UI immediately available.
2. Trigger an action that requires tool confirmation.
3. Observe that the operation fails fast (or is handled) rather than hanging for a timeout duration.

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:
  • Linux
    • npm run (Verified locally)

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[gemini-code-assist]

Summary of Changes

Hello @pdHaku0, 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 issue where tool execution could hang indefinitely in headless or non-interactive environments when a user confirmation was required but no UI listener was available to provide it. The change ensures that in such scenarios, the system fails fast by automatically denying the confirmation, thereby preventing timeouts and improving system responsiveness.

Highlights

• Tool Confirmation Logic: Modified the ASK_USER policy in MessageBus to check for active TOOL_CONFIRMATION_REQUEST listeners. If no listeners are present, it now immediately emits a TOOL_CONFIRMATION_RESPONSE with confirmed: false instead of waiting indefinitely.

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[gemini-code-assist]

Code Review

The pull request effectively addresses the issue of tool execution hanging in headless or non-interactive environments by introducing a check for UI listeners before requesting user confirmation. If no listeners are present, it immediately responds with a TOOL_CONFIRMATION_RESPONSE indicating that confirmation was needed but could not be obtained. This is a robust solution that improves responsiveness and prevents indefinite waits, aligning well with the described problem and solution. The code is clear and the logic is sound.