> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-matt-sdk-0-3-0-run-kind.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Use Videos Video Extend with Comfy Router

> Call kling/videos-video-extend through Comfy Router: endpoint, request shape and the response Router returns.

API Reference for `kling/videos-video-extend`, served by Comfy Router from Kling.

## Quick start

Create a key in [your Comfy workspace](https://platform.comfy.org/profile/api-keys) and export it as `COMFY_API_KEY`. The Python and TypeScript snippets use the Comfy SDKs (`pip install comfy-sdk`, `npm install @comfyorg/sdk`); the cURL snippet is the same call over raw HTTP.

**Model ID:** `kling/videos-video-extend`

**Endpoint:** `POST https://api.comfy.org/v2/models/kling/videos-video-extend`

<Tabs>
  <Tab title="Wait for the result">
    <CodeGroup>
      ```python Python theme={null}
      from comfy_sdk import Comfy

      # Reads COMFY_API_KEY from the environment.
      # The SDK automatically creates an idempotency key and reuses it for automatic retries.
      with Comfy() as client:
          result = client.models.run(
              "kling/videos-video-extend",
              {
                  "cfg_scale": 0.5,
                  "prompt": "The camera keeps drifting forward down the alley.",
                  "video_id": "kling-video-6f5e4d3c2b1a",
              },
          )

      print(result)
      ```

      ```typescript TypeScript theme={null}
      import { comfy } from "@comfyorg/sdk";

      // Reads COMFY_API_KEY from the environment.
      // The SDK automatically creates an idempotency key and reuses it for automatic retries.
      const { data } = await comfy.models.run("kling/videos-video-extend", {
        cfg_scale: 0.5,
        prompt: "The camera keeps drifting forward down the alley.",
        video_id: "kling-video-6f5e4d3c2b1a",
      });

      console.log(data);
      ```

      ```bash cURL theme={null}
      curl https://api.comfy.org/v2/models/kling/videos-video-extend \
        -H "X-API-Key: $COMFY_API_KEY" \
        -H "Idempotency-Key: $(uuidgen)" \
        -H "Content-Type: application/json" \
        -d "{\"cfg_scale\": 0.5, \"prompt\": \"The camera keeps drifting forward down the alley.\", \"video_id\": \"kling-video-6f5e4d3c2b1a\"}"
      ```
    </CodeGroup>
  </Tab>

  <Tab title="Queue and collect later">
    <Note>
      Queued delivery is rolling out per workspace. Until yours is enabled, the submit route answers `403` with `X-Comfy-Error-Type: not_enabled`. Nothing about the request is wrong, and the same body works through the synchronous route in the meantime.
    </Note>

    The same body, sent to `POST https://api.comfy.org/v2/models/kling/videos-video-extend/requests`. Router answers `201` with a `request_id` as soon as the run is admitted, and the result is collected once it is ready, from this process or another one. [Queued delivery](/development/comfy-router/queue) walks through status, cancellation and collection.

    <CodeGroup>
      ```python Python theme={null}
      from comfy_sdk import Comfy

      # Reads COMFY_API_KEY from the environment.
      # Each submit() call mints its own Idempotency-Key and reuses it for automatic retries.
      with Comfy() as client:
          handle = client.models.submit(
              "kling/videos-video-extend",
              {
                  "cfg_scale": 0.5,
                  "prompt": "The camera keeps drifting forward down the alley.",
                  "video_id": "kling-video-6f5e4d3c2b1a",
              },
          )
          print("request_id:", handle.request_id)  # with the model ID, all another process needs

          # Poll until the request completes, waiting the Retry-After the server names.
          for update in handle.iter_events():
              print(update.status, update.queue_position)

          # The provider's own payload, the same value models.run() returns.
          # A request that failed or was cancelled raises the typed Router error here.
          result = handle.get()

      print(result)
      ```

      ```typescript TypeScript theme={null}
      import { comfy } from "@comfyorg/sdk";

      // Reads COMFY_API_KEY from the environment.
      // Each submit() call mints its own Idempotency-Key and reuses it for automatic retries.
      const handle = await comfy.models.submit("kling/videos-video-extend", {
        cfg_scale: 0.5,
        prompt: "The camera keeps drifting forward down the alley.",
        video_id: "kling-video-6f5e4d3c2b1a",
      });
      console.log("requestId:", handle.requestId); // with the model ID, all another process needs

      // Poll until the request completes, waiting the Retry-After the server names.
      for await (const update of handle.events()) {
        console.log(update.status, update.queuePosition);
      }

      // The same result models.run() returns. A request that failed or was cancelled rejects here.
      const result = await handle.get();

      console.log(result.data);
      ```

      ```bash cURL theme={null}
      # 1. Submit. Router answers 201 with request_id, status_url, response_url and cancel_url.
      curl https://api.comfy.org/v2/models/kling/videos-video-extend/requests \
        -H "X-API-Key: $COMFY_API_KEY" \
        -H "Idempotency-Key: $(uuidgen)" \
        -H "Content-Type: application/json" \
        -d "{\"cfg_scale\": 0.5, \"prompt\": \"The camera keeps drifting forward down the alley.\", \"video_id\": \"kling-video-6f5e4d3c2b1a\"}"

      # 2. Poll until status is COMPLETED, waiting the Retry-After seconds each response names.
      REQUEST_ID="<request_id from the 201 body>"
      curl -i https://api.comfy.org/v2/models/kling/videos-video-extend/requests/$REQUEST_ID/status \
        -H "X-API-Key: $COMFY_API_KEY"

      # 3. Collect. 200 with the model's native output, 202 with the status body while it is still running.
      curl https://api.comfy.org/v2/models/kling/videos-video-extend/requests/$REQUEST_ID \
        -H "X-API-Key: $COMFY_API_KEY"
      ```
    </CodeGroup>
  </Tab>
</Tabs>

## Schema

### Input

<ParamField body="callback_url" type="string (uri)">
  The callback notification address. Server will notify when the task status changes.

  Format: `uri`
</ParamField>

<ParamField body="cfg_scale" type="number" default="0.5">
  Flexibility in video generation. The higher the value, the lower the model's degree of flexibility, and the stronger the relevance to the user's prompt.

  Range: `0` to `1`

  Format: `float`
</ParamField>

<ParamField body="negative_prompt" type="string">
  Negative text prompt for elements to avoid in the extended video
</ParamField>

<ParamField body="prompt" type="string">
  Positive text prompt for guiding the video extension
</ParamField>

<ParamField body="video_id" type="string" required>
  The ID of the video to be extended. Supports videos generated by text-to-video, image-to-video, and previous video extension operations. Cannot exceed 3 minutes total duration after extension.
</ParamField>

Generated from the schema Router serves at `GET /v2/models/kling/videos-video-extend/openapi.json`, the same document it validates a call against before the request reaches the provider.

### Output

<ResponseField name="code" type="integer">
  Error code
</ResponseField>

<ResponseField name="data" type="object" />

<ResponseField name="data.created_at" type="integer">
  Task creation time
</ResponseField>

<ResponseField name="data.final_unit_deduction" type="string">
  The deduction units of task
</ResponseField>

<ResponseField name="data.task_id" type="string">
  Task ID
</ResponseField>

<ResponseField name="data.task_info" type="object" />

<ResponseField name="data.task_info.external_task_id" type="string" />

<ResponseField name="data.task_result" type="object" />

<ResponseField name="data.task_result.videos" type="object[]" />

<ResponseField name="data.task_result.videos[].duration" type="string">
  Total video duration in seconds
</ResponseField>

<ResponseField name="data.task_result.videos[].id" type="string">
  Generated video ID
</ResponseField>

<ResponseField name="data.task_result.videos[].url" type="string (uri)">
  URL for generated video

  Format: `uri`
</ResponseField>

<ResponseField name="data.task_result.videos[].watermark_url" type="string (uri)">
  URL for generated video with watermark, hotlink protection format

  Format: `uri`
</ResponseField>

<ResponseField name="data.task_status" type="string">
  Task Status

  Possible values: `submitted`, `processing`, `succeed`, `failed`
</ResponseField>

<ResponseField name="data.updated_at" type="integer">
  Task update time
</ResponseField>

<ResponseField name="message" type="string">
  Error message
</ResponseField>

<ResponseField name="request_id" type="string">
  Request ID
</ResponseField>

## Examples

### Input

```json theme={null}
{
  "cfg_scale": 0.5,
  "prompt": "The camera keeps drifting forward down the alley.",
  "video_id": "kling-video-6f5e4d3c2b1a"
}
```

### Output

```json theme={null}
{
  "code": 0,
  "data": {
    "created_at": 1798761600000,
    "final_unit_deduction": "1.00",
    "task_id": "kling-video-extend-task-0a1b2c3d4e5f",
    "task_result": {
      "videos": [
        {
          "duration": "10",
          "id": "kling-video-5f4e3d2c1b0a",
          "url": "https://example.invalid/kling/videos-video-extend/generated.mp4"
        }
      ]
    },
    "task_status": "succeed",
    "updated_at": 1798762020000
  },
  "message": "SUCCEED",
  "request_id": "c7b6a504-3f2e-41d0-8a9c-6b5d4e3f2a10"
}
```

## Before you ship

The SDKs create an `Idempotency-Key` and reuse it for automatic retries. For manual retries, reuse the original key. Router can hold the connection for up to 10 minutes.

When a request fails, Router sends an `X-Comfy-Error-Type` response header explaining why. A `422` means Router rejected the input before calling the provider. Download generated assets promptly because [result URLs can expire](/development/comfy-router/reference#result-assets).

<CardGroup cols={3}>
  <Card title="Headers" icon="list" href="/development/comfy-router/headers">
    Authentication, idempotency, request IDs, error buckets, retry pacing, spend limits.
  </Card>

  <Card title="Using the Router API" icon="code" href="/development/comfy-router/api">
    Model discovery, validation errors, retries, and billing.
  </Card>

  <Card title="Limitations" icon="triangle-exclamation" href="/development/comfy-router/limitations">
    What Router does not do today, and what to use instead.
  </Card>
</CardGroup>