feat(core): isolate sub-agent activeExtensionName via AsyncLocalStorage

[mahimashanware]

Summary

Phase 4 of the dynamic extension plan directory resolution implementation. This PR introduces the concept of an activeExtensionName throughout the Config and AgentLoopContext and implements robust AsyncLocalStorage isolation for sub-agents.

Details

• Global Context Propagation: Modifies Config to track activeExtensionName alongside WorkspaceContext.
• Sub-agent Isolation: Integrates the "Lazy-Loading" design's requirement for strict scoping. Uses AsyncLocalStorage in scoped-config.ts to implement runWithScopedActiveExtension. This ensures that any context switches triggered by a sub-agent (e.g., executing a command that activates an extension context) remain isolated and do not leak back and pollute the global main session.
• Tools Context Update: Context routing passed to tools respects this scoping to safely map tool invocations to the proper plan directory.

Related Issues

Depends on Phase 3 (PR #25384).

How to Validate

Run unit tests for scoped config execution:

npm test -w @google/gemini-cli-core -- src/config/scoped-config.test.ts src/agents/local-executor.test.ts

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

[github-actions]

🛑 Action Required: Evaluation Approval

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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 significantly enhances the dynamic extension plan directory resolution by introducing a mechanism to isolate the activeExtensionName for sub-agents. This ensures that operations performed within a sub-agent's context, particularly those involving extension-specific configurations like plan directories, do not inadvertently alter or interfere with the main agent's context. The changes provide a more robust and predictable environment for agent execution, especially when dealing with multiple extensions or nested agent calls.

Highlights

• Sub-agent Context Isolation: Implemented robust AsyncLocalStorage isolation for sub-agents to prevent activeExtensionName context leaks. This ensures that extension activations triggered by a sub-agent remain scoped and do not affect the global session.
• Active Extension Tracking: Modified the Config and AgentLoopContext to track the activeExtensionName, which is crucial for dynamic extension plan directory resolution.
• Scoped Plan Directory Resolution: Updated various tools and prompt providers (PromptProvider, EditToolInvocation, ExitPlanModeTool, ToolRegistry, WriteFileToolInvocation) to respect the activeExtensionName when resolving plan directories, allowing for custom plan directories per active extension.
• New Scoping Utilities: Introduced runWithScopedActiveExtension and getActiveExtensionOverride in scoped-config.ts to manage and retrieve the isolated activeExtensionName.

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[gemini-code-assist]

Code Review

This pull request introduces scoped isolation for the active extension name using AsyncLocalStorage, ensuring that sub-agents do not leak context. It updates the Config class and various tools, including Edit, WriteFile, and ExitPlanMode, to retrieve extension-specific settings such as the plans directory. A review comment correctly identifies code duplication in exit-plan-mode.ts regarding the resolution of the plans directory, suggesting a refactor for better consistency.

[gemini-code-assist]

This getResolvedPlansDir method is a duplicate of the one in the ExitPlanModeTool class (lines 56-66). To ensure consistent path resolution, use a single, robust function (like resolveToRealPath) for all related path validations across components. Consider refactoring to remove this duplication, for instance by resolving the plans directory once in ExitPlanModeTool and passing it to the ExitPlanModeInvocation constructor.

References

1. Ensure consistent path resolution by using a single, robust function (e.g., resolveToRealPath) for all related path validations, including internal validations in components like WorkspaceContext.

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