查询视频任务（原生接口）

curl "$BASE_URL/v1beta/operations/{operation_id}" \
  -H "Authorization: Bearer $TOKEN"

{
  "name": "operations/abc123xyz",
  "done": false
}

{
  "name": "operations/abc123xyz",
  "done": true,
  "response": {
    "generateVideoResponse": {
      "generatedSamples": [{
        "video": {"uri": "https://.../video.mp4"},
        "metadata": {
          "durationSeconds": 6,
          "size": "1280x720"
        }
      }]
    }
  }
}

import time

def poll_operation(op_id, timeout=600):
    start = time.time()
    interval = 6

    while time.time() - start < timeout:
        resp = get_operation(op_id)
        if resp.get("done"):
            return resp
        time.sleep(interval)
        interval = min(interval * 1.5, 30)

    raise TimeoutError("Operation timed out")