Streaming
Streaming lets you subscribe to updates of the agent run as it proceeds. This can be useful for showing the end-user progress updates and partial responses.
To stream, you can callRunner.run_streamed(), which will give you aRunResultStreaming. Callingresult.stream_events() gives you an async stream ofStreamEvent objects, which are described below.
Raw response events
RawResponsesStreamEvent are raw events passed directly from the LLM. They are in OpenAI Responses API format, which means each event has a type (likeresponse.created,response.output_text.delta, etc) and data. These events are useful if you want to stream response messages to the user as soon as they are generated.
For example, this will output the text generated by the LLM token-by-token.
importasynciofromopenai.types.responsesimportResponseTextDeltaEventfromagentsimportAgent,Runnerasyncdefmain():agent=Agent(name="Joker",instructions="You are a helpful assistant.",)result=Runner.run_streamed(agent,input="Please tell me 5 jokes.")asyncforeventinresult.stream_events():ifevent.type=="raw_response_event"andisinstance(event.data,ResponseTextDeltaEvent):print(event.data.delta,end="",flush=True)if__name__=="__main__":asyncio.run(main())Run item events and agent events
RunItemStreamEvents are higher level events. They inform you when an item has been fully generated. This allows you to push progress updates at the level of "message generated", "tool ran", etc, instead of each token. Similarly,AgentUpdatedStreamEvent gives you updates when the current agent changes (e.g. as the result of a handoff).
For example, this will ignore raw events and stream updates to the user.
importasyncioimportrandomfromagentsimportAgent,ItemHelpers,Runner,function_tool@function_tooldefhow_many_jokes()->int:returnrandom.randint(1,10)asyncdefmain():agent=Agent(name="Joker",instructions="First call the `how_many_jokes` tool, then tell that many jokes.",tools=[how_many_jokes],)result=Runner.run_streamed(agent,input="Hello",)print("=== Run starting ===")asyncforeventinresult.stream_events():# We'll ignore the raw responses event deltasifevent.type=="raw_response_event":continue# When the agent updates, print thatelifevent.type=="agent_updated_stream_event":print(f"Agent updated:{event.new_agent.name}")continue# When items are generated, print themelifevent.type=="run_item_stream_event":ifevent.item.type=="tool_call_item":print("-- Tool was called")elifevent.item.type=="tool_call_output_item":print(f"-- Tool output:{event.item.output}")elifevent.item.type=="message_output_item":print(f"-- Message output:\n{ItemHelpers.text_message_output(event.item)}")else:pass# Ignore other event typesprint("=== Run complete ===")if__name__=="__main__":asyncio.run(main())