A2aAgentExecutor.cancel() method raise NotImplementedError, making the CancelTask A2A protocol method non-functional in ADK.

[secprog]

Describe the bug

A2aAgentExecutor.cancel() method raise NotImplementedError, making the CancelTask A2A protocol method non-functional in ADK.

Root Cause

The cancel method was defined as an abstract method in the a2a-sdk's AgentExecutor base class but was not implemented in ADK's A2aAgentExecutor. Any attempt to cancel a task would fail immediately.

Impact

-CancelTask RPC method is completely non-functional
-Tasks cannot be canceled through the A2A protocol
-Clients attempting to cancel tasks will receive errors
-No cooperative cancellation workflow is available

Expected behavior

Be able to cancel an a2a task

[ryleymao]

If anyone is actively working on this already, please let me know. Otherwise I’ll proceed and open a PR shortly.