2b71469e86
_SessionBuffer.append_system_message(user_id, session_id, text) injects a synthetic SystemMessage into the named session slot (creating it if absent). ContextualBufferProxy closes over user_id + session_id so call sites need only call proxy.append_system_message(text). get_session_buffer(user_id, session_id, channel) in device_ws returns a ContextualBufferProxy, keeping the test-patchable function signature intact.
DEV
Run in DEV with command:
uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload --log-config logging.conf