refactor(a2a): remove legacy CoreToolScheduler

[adamfweidman]

Summary

Removes the legacy CoreToolScheduler and transitions the A2A server Task to exclusively rely on the event-driven Scheduler imported from @google/gemini-cli-core.

Details

• Removed Legacy Methods: Cleaned out createLegacyScheduler, _schedulerAllToolCallsComplete, and _schedulerToolCallsUpdate from packages/a2a-server/src/agent/task.ts.
• Config Adjustments: Removed the experimental enableEventDrivenScheduler properties from config.ts and settings.ts.
• Tests Re-aligned: Updated Task tests and utility tests to drop assumptions of the old legacy scheduler execution model and properly mock the toolRegistry property necessary for the event-driven Scheduler.
• Type Safety: Passed npm run typecheck and npm run lint workspace-wide after making these breaking internal removals.

Related Issues

#21468

How to Validate

1. Run the workspace test suite in packages/a2a-server: npm run test -w @google/gemini-cli-a2a-server
2. Run typechecks to ensure valid object properties: npm run typecheck -w @google/gemini-cli-a2a-server
3. Run linting to guarantee zero unused references to legacy scheduler models: npm run lint -w @google/gemini-cli-a2a-server

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-cli]

Hi @adamfweidman, thank you so much for your contribution to Gemini CLI! We really appreciate the time and effort you've put into this.

We're making some updates to our contribution process to improve how we track and review changes. Please take a moment to review our recent discussion post: Improving Our Contribution Process & Introducing New Guidelines.

Key Update: Starting January 26, 2026, the Gemini CLI project will require all pull requests to be associated with an existing issue. Any pull requests not linked to an issue by that date will be automatically closed.

Thank you for your understanding and for being a part of our community!

[gemini-cli]

Hi there! Thank you for your contribution to Gemini CLI.

To improve our contribution process and better track changes, we now require all pull requests to be associated with an existing issue, as announced in our recent discussion and as detailed in our CONTRIBUTING.md.

This pull request is being closed because it is not currently linked to an issue. Once you have updated the description of this PR to link an issue (e.g., by adding Fixes #123 or Related to #123), it will be automatically reopened.

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[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 refactors the A2A server's task management by eliminating the deprecated CoreToolScheduler. The system now relies solely on the modern, event-driven Scheduler, streamlining the codebase and removing conditional logic related to scheduler selection. This change simplifies the architecture, improves maintainability, and ensures a consistent approach to tool call scheduling within the application.

Highlights

• Legacy Scheduler Removal: The CoreToolScheduler and all its associated methods and logic have been completely removed from the Task class in packages/a2a-server/src/agent/task.ts.
• Exclusive Event-Driven Scheduler Usage: The A2A server Task now exclusively uses the event-driven Scheduler imported from @google/gemini-cli-core, simplifying the scheduling mechanism.
• Configuration Simplification: The experimental enableEventDrivenScheduler properties have been removed from config.ts and settings.ts, as the event-driven scheduler is now the default and only option.
• Test Suite Alignment: Existing tests for the Task class and utility functions have been updated to remove dependencies on the legacy scheduler's execution model and correctly mock the toolRegistry property for the event-driven scheduler.

Changelog

• packages/a2a-server/src/agent/task.test.ts
  • Removed imports for afterEach, ApprovalMode, ToolConfirmationOutcome, and ToolCall.
  • Deleted the entire _schedulerToolCallsUpdate test suite, which was specific to the legacy scheduler.
• packages/a2a-server/src/agent/task.ts
  • Removed the import of CoreToolScheduler.
  • Deleted type definitions and utility functions (ConfirmationType, VALID_CONFIRMATION_TYPES, isToolCallConfirmationDetails) related to legacy tool call confirmation.
  • Updated the scheduler property type to strictly Scheduler, removing the CoreToolScheduler union type.
  • Removed conditional logic for initializing the scheduler, now always calling setupEventDrivenScheduler().
  • Simplified the cancelAll method to directly call this.scheduler.cancelAll() without type checking.
  • Removed private methods _schedulerAllToolCallsComplete, _schedulerToolCallsUpdate, and createLegacyScheduler.
  • Simplified the dispose method to directly call this.scheduler.dispose() without type checking.
• packages/a2a-server/src/config/config.ts
  • Removed the enableEventDrivenScheduler property from the configuration loading process.
• packages/a2a-server/src/config/settings.ts
  • Removed the experimental.enableEventDrivenScheduler property from the Settings interface.
• packages/a2a-server/src/http/app.test.ts
  • Modified the getToolRegistrySpy mock to return a detailed mock object for ToolRegistry instead of a simple ApprovalMode.DEFAULT.
• packages/a2a-server/src/utils/testing_utils.ts
  • Added ToolRegistry to the list of imported types from @google/gemini-cli-core.
  • Introduced a toolRegistry getter property in createMockConfig to provide a mock ToolRegistry instance.
  • Removed the isEventDrivenSchedulerEnabled mock function from createMockConfig.

Activity

• No specific review comments or activity have been recorded on this pull request yet.

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[gemini-cli]

Thank you for linking an issue! This pull request has been automatically reopened.

[gemini-code-assist]

Code Review

This pull request is a clean refactoring that removes the legacy CoreToolScheduler and its associated logic from the A2A server. The Task class now exclusively uses the event-driven Scheduler from @google/gemini-cli-core, which simplifies the codebase by removing conditional logic, dead code, and the enableEventDrivenScheduler configuration flag. The test files and mock utilities have been updated accordingly to reflect these changes, ensuring correctness. The changes are well-executed and align with the goal of modernizing the scheduler implementation.

[github-actions]

Size Change: -4 B (0%)

Total Size: 26.5 MB

ℹ️ View Unchanged

Filename	Size	Change
./bundle/gemini.js	26 MB	-4 B (0%)
./bundle/node_modules/@google/gemini-cli-devtools/dist/client/main.js	221 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/_client-assets.js	227 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/index.js	11.5 kB	0 B
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/types.js	132 B	0 B
./bundle/sandbox-macos-permissive-open.sb	890 B	0 B
./bundle/sandbox-macos-permissive-proxied.sb	1.31 kB	0 B
./bundle/sandbox-macos-restrictive-open.sb	3.36 kB	0 B
./bundle/sandbox-macos-restrictive-proxied.sb	3.56 kB	0 B
./bundle/sandbox-macos-strict-open.sb	4.82 kB	0 B
./bundle/sandbox-macos-strict-proxied.sb	5.02 kB	0 B

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