Python: [Bug]: A2AAgent Drops context_id in Message Preparation

[sphenry]

Description

A2AAgent._prepare_message_for_a2a() does not pass Message.context_id through to A2AMessage.context_id, so every A2A request has context_id=None. Without patch, multi-turn A2A conversations lose turn correlation — orchestrator cannot track which turns belong to the same conversation.

Code Sample

Error Messages / Stack Traces

Package Versions

python-1.0.0rc4

Python Version

No response

Additional Context

No response

[eavanvalkenburg]

I have a fix up in PR #4686 to propagate context_id into the A2A protocol message shape:

• Python: preserve A2A message context_id #4686

I also updated that PR so context_id is not duplicated in A2AMessage.metadata after being promoted into A2AMessage.context_id.