Python: [Bug]: A2A CancelTaskRequest Literal Mismatch

[sphenry]

Description

agent-framework-a2a hardcodes Literal['tasks/cancel'] instead of spec-correct 'task/cancel'. Any strict A2A client sending spec-compliant task/cancel would get rejected by the SDK's own type validation.

Code Sample

Error Messages / Stack Traces

Package Versions

python-1.0.0rc4

Python Version

No response

Additional Context

No response

[eavanvalkenburg]

I rechecked this against the versions we currently support and against newer 0.3.x SDKs.

agent-framework-a2a currently supports a2a-sdk>=0.3.5,<0.3.24, and our main lock is on a2a-sdk==0.3.23. That version still defines CancelTaskRequest.method as "tasks/cancel". I also checked 0.3.24 and 0.3.25, and they still use "tasks/cancel" as well.

So this is still an upstream a2a-sdk issue, and widening our dependency range in this repo would not actually fix the literal mismatch. We closed PR #4689 because that dependency-only change would not resolve the bug here.