Enhance AgentTool to support custom services and plugins

[voborl00]

This PR enhances AgentTool to support hierarchical agent execution with shared context and persistence with unbroken backward-compatibility.
Currently, AgentTool always instantiates fresh in-memory services (Session, Artifact, Memory) and no plugins for the sub-agent. This change adds a new factory method AgentTool.create(...) that allows injecting existing service instances and a list of plugins.
This enables scenarios where a parent agent needs to share a specific session store or memory context with a sub-agent, or when specific plugins (like logging or observability) need to be propagated to the sub-agent's runner.

[gemini-code-assist]

Summary of Changes

Hello @voborl00, 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 upgrades the AgentTool's flexibility by allowing developers to define and pass custom service implementations and plugins to sub-agents. This capability is crucial for building more sophisticated and interconnected agent systems where state, data, and extended functionalities need to be consistently managed across different levels of agent interaction. The update ensures that agents can operate within a shared environment, improving overall system coherence and extensibility.

Highlights

• Hierarchical Agent Execution: The AgentTool now supports hierarchical agent execution, allowing sub-agents to inherit or share services and plugins from their parent agents.
• Injectable Services and Plugins: A new factory method AgentTool.create(...) has been introduced, enabling the injection of existing Session, Artifact, and Memory service instances, as well as a list of BasePlugin implementations, into sub-agents.
• Shared Context and Persistence: This enhancement facilitates scenarios where parent agents need to share specific session stores, memory contexts, or propagate plugins (like logging or observability) to their sub-agents, ensuring consistent context and persistence.
• Backward Compatibility: The changes maintain unbroken backward compatibility, meaning existing AgentTool usages without explicit service/plugin injection will continue to function as before, using in-memory defaults.

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[gemini-code-assist]

Code Review

This pull request enhances AgentTool to support custom services and plugins, which is a great step towards more flexible and hierarchical agent execution. The changes introduce a new factory method for AgentTool and update the runner to use injected services, maintaining backward compatibility. The implementation is solid, but I've identified one area for improvement regarding error handling that could make the code more robust.

[voborl00]

/gemini review main...appsatori:adk-java:main

[gemini-code-assist]

Code Review

This pull request enhances AgentTool to support custom services and plugins, which is a valuable improvement for enabling hierarchical agent execution with shared context. The changes are well-implemented, adding a new factory method for dependency injection while maintaining backward compatibility. The accompanying tests effectively validate the new functionality. I have a couple of suggestions to enhance robustness and code clarity.

[voborl00]

/gemini review
i have implemented all requested changes and squashed into single commit, should be all good now

[gemini-code-assist]

Code Review

This pull request effectively enhances AgentTool to support custom services and plugins, which is a great step towards more flexible and hierarchical agent compositions. The changes maintain backward compatibility and are well-tested. I have a couple of minor suggestions to improve code clarity by adding @Nullable annotations to the new methods, aligning with the existing coding style.

[voborl00]

Nullable annotations added
/gemini review

[gemini-code-assist]

Code Review

This pull request successfully enhances AgentTool to support custom services and plugins, enabling hierarchical agent execution with a shared context. The changes are well-implemented, maintaining backward compatibility by providing default in-memory services when none are injected. The new factory method provides a clean way to extend AgentTool's functionality. I've added a couple of suggestions to improve the test coverage for the new user ID propagation logic.