RemoteA2aAgent resets A2AClientFactory

[matiasanaya]

class RemoteA2aAgent(BaseAgent): takes in an a2a_client_factory: Optional[A2AClientFactory] = None but within:

async def _ensure_httpx_client(self) -> httpx.AsyncClient:

it overwrites it:

self._a2a_client_factory = A2AClientFactory(
            config=dataclasses.replace(
                self._a2a_client_factory._config,
                httpx_client=self._httpx_client,
            )
        )

which means I can't sub-class it. This is an issue because I need to override the create of A2AClientFactory.

Describe the solution you'd like
Allow the user to provide an A2AClientFactory that will be called to create the A2AClient.

Describe alternatives you've considered
For now I've resolved to monkey patching, which is far from ideal.

Additional context
This is needed in the context of the A2A <> x402 implementation, to get RemoteA2aAgent working with the x402 spec over A2A.