> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-stale2000-router-model-pages.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Use H3 Max with Comfy Router

> Call fal/h3-max through Comfy Router: endpoint, request shape and the response Router returns.

API Reference for `fal/h3-max`, served by Comfy Router from fal.

## 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:** `fal/h3-max`

**Endpoint:** `POST https://api.comfy.org/v2/models/fal/h3-max`

<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(
          "fal/h3-max",
          {
              "duration": 5,
              "prompt": "a red fox running through a snowy forest",
              "prompt_expansion_mode": "balanced",
              "resolution": "480P",
          },
      )

  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("fal/h3-max", {
    duration: 5,
    prompt: "a red fox running through a snowy forest",
    prompt_expansion_mode: "balanced",
    resolution: "480P",
  });

  console.log(data);
  ```

  ```bash cURL theme={null}
  curl https://api.comfy.org/v2/models/fal/h3-max \
    -H "X-API-Key: $COMFY_API_KEY" \
    -H "Idempotency-Key: $(uuidgen)" \
    -H "Content-Type: application/json" \
    -d "{\"duration\": 5, \"prompt\": \"a red fox running through a snowy forest\", \"prompt_expansion_mode\": \"balanced\", \"resolution\": \"480P\"}"
  ```
</CodeGroup>

## Schema

### Input

<ParamField body="aspect_ratio" type="string" default="&#x22;16:9&#x22;">
  Aspect ratio: 21:9, 16:9, 4:3, 1:1, 3:4, or 9:16.
</ParamField>

<ParamField body="duration" type="integer" default="5">
  Duration of the generated video in seconds.
</ParamField>

<ParamField body="enable_safety_checker" type="boolean" default="true">
  Enable the safety checker.
</ParamField>

<ParamField body="prompt" type="string" required>
  Text prompt for video generation.
</ParamField>

<ParamField body="prompt_expansion_mode" type="string" required>
  How much effort to spend rewriting the prompt before generation: balanced or quality.
</ParamField>

<ParamField body="resolution" type="string" default="&#x22;768P&#x22;">
  Resolution of the generated video: 480P or 768P.
</ParamField>

<ParamField body="seed" type="integer">
  Random seed. A random seed is selected when omitted.
</ParamField>

<ParamField body="sync_mode" type="boolean">
  Return the generated video as base64 instead of a CDN URL.
</ParamField>

Generated from the schema Router serves at `GET /v2/models/fal/h3-max/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}
{
  "duration": 5,
  "prompt": "a red fox running through a snowy forest",
  "prompt_expansion_mode": "balanced",
  "resolution": "480P"
}
```

## 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/models">
    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>