curl --request POST 'https://xcompute.us/kling/v1/videos/video-extend' \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "model_name": "kling-v3",
    "video_id": "UPSTREAM_VIDEO_ID",
    "prompt": "镜头继续向前移动并逐渐升高"
  }'