parse_stream_response

def parse_stream_response(response: StreamResponse) -> A2AEvent:
    """Decode a wire ``StreamResponse`` into a typed A2A event.

    Picks typed subclasses where possible — text-only artifacts become
    ``A2ATextArtifact``, ``tool-call+json`` artifacts become
    ``A2AToolCallArtifact``. Unrecognised artifact shapes fall through
    to the base ``A2ATaskArtifactUpdate``.
    """
    payload = response.WhichOneof("payload")
    if payload == "task":
        return A2ATaskSnapshot(task=response.task)
    if payload == "message":
        return A2AMessage(message=response.message)
    if payload == "status_update":
        update = response.status_update
        return A2ATaskStatusUpdate(update=update, state=update.status.state)
    if payload == "artifact_update":
        return parse_artifact_update(response.artifact_update)
    raise ValueError(f"Unexpected StreamResponse payload: {payload!r}")