{
  "context": "Evaluates how well the solution streams HTTP responses using xmlhttprequest by emitting progress updates during the LOADING phase, then completing or aborting cleanly. Scoring focuses solely on correct use of XMLHttpRequest APIs for streaming progress, completion, and cancellation.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "LOADING hook",
      "description": "Sets up XMLHttpRequest with onreadystatechange/addEventListener to detect readyState === LOADING (3) and emit progress callbacks before DONE.",
      "max_score": 30
    },
    {
      "name": "Chunk updates",
      "description": "Uses responseText growth during LOADING to call the provided onProgress for each chunk (not just once at completion), passing cumulative length and latest fragment.",
      "max_score": 20
    },
    {
      "name": "Single-chunk progress",
      "description": "Even when the response arrives in a single chunk, still triggers at least one LOADING-driven progress callback before resolving.",
      "max_score": 10
    },
    {
      "name": "Final completion",
      "description": "Waits for readyState === DONE (4) or load event to resolve with the full concatenated response and byte count after prior LOADING callbacks.",
      "max_score": 15
    },
    {
      "name": "Abort handling",
      "description": "Respects AbortSignal/abort requests by invoking xhr.abort(), ceasing further LOADING callbacks, and surfacing an aborted result path.",
      "max_score": 15
    },
    {
      "name": "Request setup",
      "description": "Initializes XMLHttpRequest with async open/send against the provided URL and avoids sync mode so streaming LOADING events can fire.",
      "max_score": 10
    }
  ]
}