Can't the run_name when running graph

[Daniel-963]

when i def the chatbot using follow code,i cant get the name when run the workflow

async def chatbot1(state: State, config: RunnableConfig):
config["run_name"] = "chatbot1"
return {"messages": [await llm1.ainvoke(state["messages"], config)]}

here i cant get name

async def message_generator(user_input: str):
"""Generate streaming messages from the graph."""
inputs = [HumanMessage(content=user_input)]

async for msg, metadata in graph.astream(
    {"messages": inputs}, stream_mode="messages"
):
    # here is none.
    # but i can get it when i using second way
    print(msg.name)
    yield json.dumps({"content": msg.content})

but when using follow code,i can

async def chatbot1(state: State, config: RunnableConfig):
    RunnableConfig(run_name="chatbot1")
    return {"messages": [await llm1.ainvoke(state["messages"], RunnableConfig(run_name="chatbot1"))]}

that's why? is it a bug?