Public Invocation Context for Global Instructions Plugin

[juanfcastropiccolo]

Summary

This PR addresses the TODO comment in CallbackContext.__init__ by exposing the invocation_context as a public property for Agent Development Kit plugin use.

Problem

The GlobalInstructionPlugin and potentially other ADK plugins need access to the invocation_context to create ReadonlyContext instances. Currently, only the private _invocation_context attribute is available, causing AttributeError when plugins attempt to access callback_context.invocation_context.

Solution

Added a public @property method invocation_context() to the CallbackContext class that returns self._invocation_context. This follows the same pattern used for other context properties like state and session.

Changes

• Added invocation_context property to CallbackContext class
• Added comprehensive docstring explaining this if for ADK plugin development
• Mantains backward compatibility (no breaking changes)

Testing

• Verified that GlobalInstructionPlugin.before_model_callback now works correctly
• No linting errors
• Follows existing code style and patterns in the codebase

Related

Resolves the TODO: "make this public for Agent Development Kit, but private for users."

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[gemini-code-assist]

Summary of Changes

Hello @juanfcastropiccolo, 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 introduces a public invocation_context property to the CallbackContext class, enabling Agent Development Kit (ADK) plugins to access the underlying invocation context. This modification directly addresses a problem where ADK plugins, like the GlobalInstructionPlugin, required this context but could only access a private attribute, leading to runtime errors. The change ensures proper functionality for ADK plugin development while maintaining backward compatibility and adhering to established coding patterns.

Highlights

• Public Invocation Context: The invocation_context is now exposed as a public property within the CallbackContext class, specifically for use by Agent Development Kit (ADK) plugins.
• Resolves AttributeError: This change resolves an AttributeError encountered by ADK plugins, such as GlobalInstructionPlugin, when attempting to access the previously private _invocation_context.
• Addresses TODO Comment: A long-standing TODO comment in CallbackContext.__init__ regarding making the invocation context public for ADK development has been addressed.

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[gemini-code-assist]

Code Review

This pull request correctly exposes the invocation_context as a public property on CallbackContext to be used by ADK plugins, resolving a TODO item. The implementation is straightforward and follows existing patterns in the codebase. I have one suggestion to improve the docstring for this new property by removing an implementation note to make it cleaner for public consumption.

[adk-bot]

Response from ADK Triaging Agent

Hello @juanfcastropiccolo, thank you for creating this PR!

To help us review this PR, could you please create and associate a GitHub issue with this PR?

In addition, could you please expand on the testing plan and provide logs or a screenshot demonstrating the fix?

This information will help reviewers to review your PR more efficiently. Thanks!

[juanfcastropiccolo]

hi @hangfei @polong-lin , could you please review this? :) thanks in advance!