{
  "execution_mode": "actual loopback HTTP; controlled text fixture, no model inference",
  "http_status": 200,
  "content_type": "text/event-stream; charset=utf-8",
  "content_events": 2,
  "done_marker": "data: [DONE]",
  "first_payload": {
    "token": "line one\nline two"
  },
  "backend_steps": 2,
  "backend_released": true
}