fix(core): handle AbortError when ESC cancels tool execution

[PrasannaPal21]

When a user presses ESC to cancel an in-flight tool call (e.g. google_web_search), the underlying request can reject with AbortError. Treat AbortError as a normal cancellation so the CLI returns to the prompt without surfacing a raw stack trace.

Fixes #20839

Summary

• Handle AbortError during tool execution as a normal cancellation so the CLI shows a clean “Request cancelled” message and returns to the prompt without a stack trace.

Details

• Treat AbortError thrown during tool execution as cancellation (instead of an unhandled exception/error result).
• Ensure google_web_search returns a clean cancelled result when the abort is caught within the tool.

Related Issues

Fixes #20839

How to Validate

1. Build + start the CLI from source:
   • npm run build --workspace=@google/gemini-cli-devtools
   • npm run build
   • npm run start
2. Trigger a web search (anything that invokes google_web_search).
3. While the search is in progress, press ESC to cancel.
4. Confirm:
   • The CLI shows a cancellation message (e.g. “Request cancelled.”).
   • No raw AbortError stack trace is printed.
   • The CLI returns to the prompt and continues normally.

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 enhances the user experience by gracefully handling AbortError exceptions that can occur when a user cancels an in-flight tool execution, such as a web search. Instead of surfacing raw stack traces, the system now recognizes these errors as cancellations, providing clean, user-friendly messages and returning control to the CLI prompt, thus improving the overall stability and polish of the command-line interface.

Highlights

• Graceful AbortError Handling: The system now explicitly checks for AbortError during tool execution and treats it as a normal cancellation event, preventing raw stack traces from being displayed to the user.
• Improved User Experience for Cancellations: When a tool execution is cancelled, either by user action (ESC key) or an AbortError, the CLI will now display a clean 'Operation cancelled.' or 'User cancelled tool execution.' message and return to the prompt.
• Specific Web Search Cancellation Message: The google_web_search tool has been updated to return a specific 'Web search was cancelled.' message when an AbortError occurs during its execution, ensuring consistent and clear feedback.

Changelog

• packages/core/src/scheduler/tool-executor.ts
  • Updated error handling logic to explicitly identify and process AbortError instances as cancellations.
  • Modified cancellation message generation to differentiate between generic user cancellations and AbortError-driven cancellations.
• packages/core/src/tools/web-search.ts
  • Implemented specific AbortError handling within the WebSearchToolInvocation to return a tailored cancellation result.

Activity

• The pull request was opened by PrasannaPal21 to address an issue where pressing ESC to cancel a tool call resulted in a raw AbortError stack trace.
• The author provided a detailed summary, specific details, related issues, and validation steps for the changes.

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[gemini-code-assist]

Code Review

This pull request correctly handles AbortError during tool execution, treating it as a cancellation to prevent unhandled exception stack traces from being shown to the user. The changes are implemented in the central ToolExecutor for generic handling, and specifically within the google_web_search tool for a more tailored cancellation message. The implementation is sound, but there is a small area for improvement regarding code duplication, as noted in the specific comment, which also aligns with best practices for consistent cancellation handling.

[gemini-code-assist]

This logic for identifying an AbortError is also used in packages/core/src/tools/web-search.ts. To improve maintainability and promote code reuse, consider extracting this check into a shared utility function (e.g., in packages/core/src/utils/errors.ts). This would prevent potential inconsistencies if the definition of an abort error needs to be updated in the future.

References

1. Asynchronous operations that can be cancelled by the user should accept and propagate an AbortSignal to ensure cancellability and prevent dangling processes or network requests. Consistent identification of AbortError is crucial for robust cancellation handling across the repository.
2. Asynchronous operations waiting for user input via the MessageBus should rely on the provided AbortSignal for cancellation, rather than implementing a separate timeout, to maintain consistency with existing patterns. Centralizing AbortError identification supports consistent cancellation logic.

[Adib234]

Can we add some tests for this and resolve the merge conflicts?

[PrasannaPal21]

Can we add some tests for this and resolve the merge conflicts?

Yes, on it

edit: @Adib234 Ive added the tests and resolved the merge conflicts, please take a look..

[PrasannaPal21]

hey @Adib234, fixed the linting error, can you run the ci again?