> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-chore-sync-comfy-api-v2-spec.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 at [platform.comfy.org/profile/api-keys](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`

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

  # Reads COMFY_API_KEY from the environment. Each call sends a fresh
  # Idempotency-Key and waits up to 10 minutes for the finished result.
  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. Each call sends a fresh
  // Idempotency-Key and waits up to 10 minutes for the finished result.
  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>

## 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

Router does not publish an output schema for this model.

## Examples

### Input

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

## Before you ship

The snippets above are the shortest working call. Three things are the same for every model and are documented once on the [Comfy Router headers](/development/comfy-router/headers) page: send an `Idempotency-Key` on every paid call and reuse it when you retry, expect the connection to be held up to Router's 10 minute deadline, and keep `X-Comfy-Request-Id` from every response. The SDKs do all three for you; the cURL tab does none of them. On failure, `X-Comfy-Error-Type` names the bucket, and a `422` means the body failed the model's schema and was never billed.

<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="Quick Start" icon="rocket" href="/development/comfy-router/quickstart">
    Typed error handling in Python and TypeScript, reading the 422, walking the catalog.
  </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>