> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-codex-api-first-result.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Use LTX 2.5 Fast with Comfy Router

> Call ltx/ltx-2-5-fast through Comfy Router: endpoint, request shape and the response Router returns.

API Reference for `ltx/ltx-2-5-fast`, served by Comfy Router from LTX.

## 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:** `ltx/ltx-2-5-fast`

**Endpoint:** `POST https://api.comfy.org/v2/models/ltx/ltx-2-5-fast`

<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(
              "ltx/ltx-2-5-fast",
              {
                  "duration": 2,
                  "fps": 24,
                  "generate_audio": False,
                  "prompt": "A single red maple leaf resting on a plain white background.",
                  "resolution": "1280x720",
              },
          )

      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("ltx/ltx-2-5-fast", {
        duration: 2,
        fps: 24,
        generate_audio: false,
        prompt: "A single red maple leaf resting on a plain white background.",
        resolution: "1280x720",
      });

      console.log(data);
      ```

      ```bash cURL theme={null}
      curl https://api.comfy.org/v2/models/ltx/ltx-2-5-fast \
        -H "X-API-Key: $COMFY_API_KEY" \
        -H "Idempotency-Key: $(uuidgen)" \
        -H "Content-Type: application/json" \
        -d "{\"duration\": 2, \"fps\": 24, \"generate_audio\": false, \"prompt\": \"A single red maple leaf resting on a plain white background.\", \"resolution\": \"1280x720\"}"
      ```
    </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/ltx/ltx-2-5-fast/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(
              "ltx/ltx-2-5-fast",
              {
                  "duration": 2,
                  "fps": 24,
                  "generate_audio": False,
                  "prompt": "A single red maple leaf resting on a plain white background.",
                  "resolution": "1280x720",
              },
          )
          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("ltx/ltx-2-5-fast", {
        duration: 2,
        fps: 24,
        generate_audio: false,
        prompt: "A single red maple leaf resting on a plain white background.",
        resolution: "1280x720",
      });
      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/ltx/ltx-2-5-fast/requests \
        -H "X-API-Key: $COMFY_API_KEY" \
        -H "Idempotency-Key: $(uuidgen)" \
        -H "Content-Type: application/json" \
        -d "{\"duration\": 2, \"fps\": 24, \"generate_audio\": false, \"prompt\": \"A single red maple leaf resting on a plain white background.\", \"resolution\": \"1280x720\"}"

      # 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/ltx/ltx-2-5-fast/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/ltx/ltx-2-5-fast/requests/$REQUEST_ID \
        -H "X-API-Key: $COMFY_API_KEY"
      ```
    </CodeGroup>
  </Tab>
</Tabs>

## Schema

### Input

<ParamField body="duration" type="integer" required>
  Video duration in seconds (maximum depends on resolution and frame rate)

  Possible values: `2`, `3`, `4`, `5`, `6`, `8`, `10`, `12`, `14`, `16`, `18`, `20`
</ParamField>

<ParamField body="fps" type="integer" default="25">
  Frame rate in frames per second

  Possible values: `24`, `25`, `48`, `50`
</ParamField>

<ParamField body="generate_audio" type="boolean" default="true">
  Generate audio for the video
</ParamField>

<ParamField body="model" type="string">
  Model to use for generation. On the Comfy Router route `POST /v2/models/ltx/{model}` this field is supplied from the path and may be omitted. The spellings LTX serves on this operation -- the set Comfy Router addresses as `ltx/<model>` -- are ltx-2-5-fast and ltx-2-5-pro; they are written out here rather than constrained to an enum for the reason the comment above gives. Which resolutions each one admits is the `x-comfy-model-resolutions` matrix on the `resolution` property below.
</ParamField>

<ParamField body="prompt" type="string" required>
  Text prompt describing the desired video content
</ParamField>

<ParamField body="resolution" type="string" required>
  Output video resolution. The enum is the union over all models; the supported set is per model. Supported pairs: ltx-2-5-fast: 1280x720, 720x1280, 1920x1080, 1080x1920, 2560x1440, 1440x2560, 3840x2160, 2160x3840; ltx-2-5-pro: 1280x720, 720x1280, 1920x1080, 1080x1920. Other (model, resolution) pairs are not supported; the v2 routes reject them with 400. The same matrix is published machine-readably in this property's x-comfy-model-resolutions extension.

  Possible values: `1280x720`, `720x1280`, `1920x1080`, `1080x1920`, `2560x1440`, `1440x2560`, `3840x2160`, `2160x3840`
</ParamField>

Generated from the schema Router serves at `GET /v2/models/ltx/ltx-2-5-fast/openapi.json`, the same document it validates a call against before the request reaches the provider.

### Output

<ResponseField name="completed_at" type="string">
  Job completion timestamp (ISO 8601)
</ResponseField>

<ResponseField name="created_at" type="string">
  Job creation timestamp (ISO 8601)
</ResponseField>

<ResponseField name="error" type="object">
  Present when status is failed
</ResponseField>

<ResponseField name="error.message" type="string" />

<ResponseField name="error.type" type="string" />

<ResponseField name="id" type="string">
  Unique job identifier
</ResponseField>

<ResponseField name="result" type="object">
  Present when status is completed; output URLs expire 24 hours after completion
</ResponseField>

<ResponseField name="result.video_url" type="string">
  URL of the generated video
</ResponseField>

<ResponseField name="status" type="string">
  Job status (pending, processing, completed, failed)
</ResponseField>

## Examples

### Input

```json theme={null}
{
  "duration": 2,
  "fps": 24,
  "generate_audio": false,
  "prompt": "A single red maple leaf resting on a plain white background.",
  "resolution": "1280x720"
}
```

### Output

```json theme={null}
{
  "completed_at": "2026-01-01T00:02:10Z",
  "created_at": "2026-01-01T00:00:00Z",
  "id": "3f7a1b28-5c0d-4e91-8a6f-1b2c3d4e5f60",
  "result": {
    "video_url": "https://example.invalid/ltx/generated.mp4"
  },
  "status": "completed"
}
```

## 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>