fix(a2a): set final=True for error TaskStatusUpdateEvent in event_converter

[kuishou68]

Closes #5388

Problem

In _create_error_status_event inside src/google/adk/a2a/converters/event_converter.py, the TaskStatusUpdateEvent for a failed task is incorrectly created with final=False:

return TaskStatusUpdateEvent(
    ...
    status=TaskStatus(state=TaskState.failed, ...),
    final=False,  # BUG: should be True
)

A failed state is terminal — no further events will follow, so final must be True. Consumers that check this flag will otherwise wait indefinitely or mishandle the error.

Fix

Change final=False → final=True in _create_error_status_event.

The equivalent code in from_adk_event.py already uses final=True correctly (line 154), so this change makes event_converter.py consistent.

Testing

Existing unit tests for error event conversion should be updated/added to assert final=True.

Signed-off-by: Cocoon-Break 54054995+kuishou68@users.noreply.github.com

[adk-bot]

Response from ADK Triaging Agent

Hello @kuishou68, thank you for your contribution!

Your PR description is very clear and it's great that you've included an associated issue and a testing plan.

As per our contribution guidelines, could you please also include a summary of the passed pytest results to verify the fix? This will help speed up the review process.

Thanks!