fix: return mandatory fields from list_tasks

[ishymko]

According to the spec all response fields are mandatory. Update implementation and add tests to cover.

Re #515

[gemini-code-assist]

Summary of Changes

Hello @ishymko, 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 addresses a compliance issue with the A2A protocol specification by ensuring that all mandatory fields in the ListTasksResponse are consistently returned. The changes involve streamlining the task processing within the default request handler and modifying the task store implementations to explicitly include total_size and page_size, while also refining how next_page_token is handled. Comprehensive tests have been added and updated to verify these changes.

Highlights

• Protocol Compliance: Updated ListTasksResponse to ensure total_size and page_size are always returned, aligning with the A2A protocol specification for mandatory fields.
• Code Refactoring: Refactored the on_list_tasks handler in default_request_handler.py to simplify task processing logic, removing redundant task copying.
• Pagination Handling: Modified next_page_token handling in both database_task_store.py and inmemory_task_store.py to return None instead of an empty string when no next page exists, as per spec, and explicitly included page_size.
• Test Coverage: Introduced new and updated existing integration and unit tests to validate the correct return of mandatory fields (total_size and page_size) in ListTasksResponse.
• Subproject Addition: Added tck/a2a-tck as a Git subproject.

Changelog

• src/a2a/server/request_handlers/default_request_handler.py
  • Simplified the logic for processing tasks in on_list_tasks by directly modifying the task object and returning the page object.
• src/a2a/server/tasks/database_task_store.py
  • Modified list method to include page_size in the ListTasksResponse.
  • Removed the or '' fallback for next_page_token.
• src/a2a/server/tasks/inmemory_task_store.py
  • Explicitly calculated and included page_size in the ListTasksResponse.
  • Removed the or '' fallback for next_page_token.
• tck/a2a-tck
  • Added a new Git subproject.
• tests/integration/test_client_server_integration.py
  • Updated LIST_TASKS_RESPONSE definition to include total_size and page_size.
  • Added assertions for total_size and page_size in test_http_transport_list_tasks.
• tests/integration/test_end_to_end.py
  • Added assertions for total_size and page_size in the test_end_to_end_list_tasks integration test.
• tests/server/tasks/test_database_task_store.py
  • Imported DEFAULT_LIST_TASKS_PAGE_SIZE.
  • Added an assertion for page.page_size in test_list_tasks.
• tests/server/tasks/test_inmemory_task_store.py
  • Imported DEFAULT_LIST_TASKS_PAGE_SIZE.
  • Added an assertion for page.page_size in test_list_tasks.

Activity

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[gemini-code-assist]

Code Review

This pull request correctly updates the list_tasks implementation to return mandatory fields as per the specification, improving compliance and code clarity. The associated tests have also been updated. However, I've identified a regression where next_page_token is not handled correctly when it is None, which could lead to runtime errors. I've provided specific suggestions to address this. Overall, these are good changes.