Callback

Pass callback_url when creating the task. The system will automatically poll the upstream provider and send a POST request to your URL when the task completes or fails.

Headers

Header	Description
`Content-Type`	`application/json`
`X-Event`	Event type: `task.completed` or `task.failed`
`X-Task-Id`	Task ID
`X-Timestamp`	Unix timestamp (seconds)

Completed

{
  "id": "7d89c51e-9430-410e-909e-df347131ebaa",
  "status": "completed",
  "model": "doubao-seedance-2.0",
  "created_at": 1774790227,
  "completed_at": 1774796529,
  "output": {
    "urls": [
      "https://ark-acg-cn-beijing.tos-cn-beijing.volces.com/doubao-seedance-2-0/...mp4?X-Tos-Algorithm=..."
    ],
    "metadata": {
      "seed": 41485,
      "ratio": "16:9",
      "duration": 5,
      "resolution": "480p",
      "generate_audio": true,
      "framespersecond": 24
    }
  }
}

Failed

{
  "id": "57c8772c-f834-46f3-9b7d-81f92e104050",
  "status": "failed",
  "model": "doubao-seedance-2.0",
  "created_at": 1774793758,
  "error": {
    "code": "upstream_error",
    "message": "The request failed because the input text may contain sensitive information. Request id: 0217747937596950e290995bd2535df6af5f05331d9ca5663eeee"
  }
}

When a task fails, pre-charged credits are automatically refunded.

Retry Policy

If your server is unreachable or returns a non-2xx status, the system will retry up to 3 times:

Attempt	Timing
1st	Immediate
2nd	3 minutes later
3rd	10 minutes later

If all 3 attempts fail, the callback is marked as failed. You can always fall back to polling GET /v1/tasks/{taskId} to check the final status.