Async Tasks / Async Tasks

Async Tasks API

Image and video generation use the unified /v1/tasks interface. Video models use asynchronous invocation (create a task to get a task_id, then poll for the result), while image models (such as wan2.6-t2i) use synchronous invocation, returning the result directly without polling. Video generation typically takes 1-5 minutes.

HTTP Invocation Workflow

Create task and get task_id

POSThttps://nexusflow.vip/v1/tasks

Poll result by task_id

GEThttps://nexusflow.vip/v1/tasks/{task_id}

Note:

After successful creation, use the returned id (i.e., task_id) to query results. Do not create duplicate tasks; just poll to retrieve results.
Image models (such as wan2.6-t2i) are synchronous; the creation request returns the result directly, no polling needed.
Video models polling recommended interval 10-15 seconds.
task_id query validity period 24 hours; it cannot be queried after expiration.
Output file URL validity period 24 hours; please download and save immediately after retrieval.
Only image and video models support the /v1/tasks interface; chat models use /v1/chat/completions.

Step 1: Create Task

Example Model:wan2.6-t2i

Request Parameters

Parameters	Type	Required	Description
`model`	string	*	Model ID, such as wan2.6-t2i. See the Models documentation for the full list.
`prompt`	string	*	Text prompt, describing the desired image content.
`negative_prompt`	string	-	Negative prompt, describing content you do not want in the output.
`size`	string	-	Output image size, such as 1024x1024 (default), 720x1280, 1280x720, etc.
`n`	integer	-	Number of images to generate, default 1, up to 4.
`seed`	integer	-	Random seed; a fixed seed improves reproducibility.

Request Example

curl -X POST 'https://nexusflow.vip/v1/tasks' \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "wan2.6-t2i",
    "prompt": "An orange cat standing on the moon's surface, with Earth in the background, cyberpunk style, 4K ultra HD",
    "size": "1024x1024",
    "n": 1
  }'

Step 1 Response: Get task_id

After successful creation, task information is returned (HTTP 202). The id serves as the task_id for subsequent polling queries.

{
  "id": "task_0385dc79-5ff8-4d82-xxxx",
  "object": "task",
  "status": "running",
  "model": "wan2.6-t2i",
  "type": "image",
  "created_at": "2026-06-01T10:00:00.000Z"
}

Field	Description
`id`	Task ID (task_id). Used for polling video task results, valid for 24 hours.
`object`	Fixed value "task".
`status`	Video models start with status running; image models (such as wan2.6-t2i) are synchronous and return succeeded directly.
`model`	The model ID used.
`type`	Task type: "image" (Image Generation) or "video" (Video Generation).
`created_at`	Task creation time (ISO 8601 format).

Step 2: Poll Result by task_id

GEThttps://nexusflow.vip/v1/tasks/{task_id}

Query Request

curl https://nexusflow.vip/v1/tasks/task_0385dc79-5ff8-4d82-xxxx \
  -H "Authorization: Bearer $API_KEY"

Image task execution succeeded

{
  "id": "task_0385dc79-5ff8-4d82-xxxx",
  "object": "task",
  "status": "succeeded",
  "model": "wan2.6-t2i",
  "type": "image",
  "progress": 100,
  "output": {
    "image_url": "https://dashscope-result.oss-cn-beijing.aliyuncs.com/xxx.png"
  },
  "created_at": "2026-06-01T10:00:00.000Z",
  "completed_at": "2026-06-01T10:00:22.000Z"
}

Task Execution Failed

{
  "id": "task_0385dc79-5ff8-4d82-xxxx",
  "object": "task",
  "status": "failed",
  "model": "wan2.6-t2i",
  "type": "image",
  "error": "InvalidParameter: The parameter is invalid.",
  "created_at": "2026-06-01T10:00:00.000Z",
  "completed_at": "2026-06-01T10:00:05.000Z"
}

Response Parameters

Field	Type	Description
`id`	string	Task ID.
`object`	string	Fixed value "task".
`status`	string	Task status: pending (queued) → running (processing) → succeeded / failed.
`model`	string	The model ID used.
`type`	string	Task type: "image" or "video".
`progress`	integer	Task progress percentage 0-100.
`output`	object	Generation result (only returned on success). Image tasks include image_url; video tasks include video_url. Link valid for 24 hours.
`error`	string	Failure reason (only returned on failure).
`created_at`	string	Task creation time (ISO 8601 format).
`completed_at`	string	Task completion time (only returned for final states).

Query Task List

GEThttps://nexusflow.vip/v1/tasks?limit=20

Retrieve the current user's recent task list. Use the limit parameter to control the number of results returned (default 20, maximum 100).

curl 'https://nexusflow.vip/v1/tasks?limit=5' \
  -H "Authorization: Bearer $API_KEY"

{
  "object": "list",
  "data": [
    {
      "id": "task_0385dc79-5ff8-4d82-xxxx",
      "object": "task",
      "status": "succeeded",
      "model": "wan2.6-t2i",
      "type": "image",
      "progress": 100,
      "created_at": "2026-06-01T10:00:00.000Z",
      "completed_at": "2026-06-01T10:00:22.000Z"
    },
    {
      "id": "task_a1b2c3d4-e5f6-7890-yyyy",
      "object": "task",
      "status": "running",
      "model": "happyhorse-1.0-t2v",
      "type": "video",
      "progress": 45,
      "created_at": "2026-06-01T10:05:00.000Z",
      "completed_at": null
    }
  ]
}

Best Practices

Smart Polling Intervals

Poll image tasks every 5-10 seconds and video tasks every 10-15 seconds. Avoid sub-second polling to reduce unnecessary requests.

Separate Sync and Async

Chat requests go to /v1/chat/completions, image/video to /v1/tasks, reducing mutual interference.

Download Results Promptly

Output URLs are valid for 24 hours. Download and save files immediately after task completion.

Handle Failures and Retries

When a task fails, check the error field to determine the cause. Parameter errors require fixing before retrying; upstream timeouts can be retried by creating a new task.

HappyHorse API

View HappyHorse Video Generation dedicated documentation

Rate Limits

View limits and optimization tips for high concurrency

Full Pricing

View pricing for all models