feat(spec): Add tasks/list method with filtering and pagination to the specification

[a2a-bot]

Commit: a2aproject/A2A@0a9f629

Fixes #515 🦕

[gemini-code-assist]

Summary of Changes

Hello @a2a-bot, 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 A2A API by introducing a new ListTasks method. This method provides a robust way to query and manage tasks, offering capabilities such as filtering by context ID and task status, specifying history length, filtering by last updated time, and controlling the inclusion of artifacts. It also supports pagination, making it suitable for handling large numbers of tasks efficiently. The changes span across the gRPC definitions and the Python type definitions, ensuring full integration and usability of this new feature.

Highlights

• New ListTasks API Method: Introduced a new RPC method ListTasks to allow clients to retrieve a paginated and filterable list of tasks.
• Expanded Task Management Capabilities: Added comprehensive request and response models for ListTasks, including parameters for filtering by context_id, status, history_length, last_updated_time, and options for pagination (page_size, page_token) and artifact inclusion.
• Protocol Buffer Updates: Updated the Python generated protobuf files (a2a_pb2.py, a2a_pb2.pyi, a2a_pb2_grpc.py) to reflect the new ListTasks method and its associated message types, ensuring gRPC compatibility.
• JSON-RPC Type Definitions: Integrated the new ListTasks functionality into the a2a/types.py file with new Pydantic models for JSON-RPC requests and responses, enhancing the Python client's ability to interact with this new API.

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[gemini-code-assist]

Code Review

This pull request updates the A2A specification and the corresponding generated Python files to introduce the ListTasks functionality. The changes correctly add the necessary protobuf messages, gRPC service definitions, and Pydantic models for the JSON-RPC transport. It appears the implementation of these new endpoints in the server handlers and client transports is planned for future work.

My review focuses on the manually edited src/a2a/types.py file. I've suggested adding Pydantic validators to the ListTasksParams model to enforce constraints mentioned in the docstrings, which will improve data integrity. I also pointed out a small inconsistency in a docstring for better clarity. Overall, the changes are well-structured and align with the existing design.