: keep-alive
id: 1
event: run.started
data: {"run_id":"r1"}

:{"type":"progress","event_id":"2","pct":10}
{"type":"progress","event_id":"3","pct":20}
event: llm.chunk
id: 4
data: hello
data: world

id: 99
retry: 500

data: {"type":"final","event_id":"6"}

id: 7
data: [DONE]