# MiniMax H3 Extend (video)

> MiniMax H3 Extend adds 5 to 15 seconds of new footage after an existing clip. The prompt describes what happens next. The output is the whole clip with the new footage, or only the new footage.

Status: roasOS API v1.1. Catalog `model-catalog@2026-10-06.v5`, pricing `customer-pricing@2026-11-05.v15`. The endpoint `POST /v1/video/h3-max-extend` is live. `POST /v1/generations` stays for one minor version as a deprecated alias (see "Today").

## Endpoint
POST https://api.roasos.com/v1/video/h3-max-extend
Auth: Authorization: Bearer roasos_sk_… (scope api:write). Idempotency-Key required. quote_only / quote_id / webhook_url as in https://docs.roasos.com/llms.txt.

## Good at
Continue a hero shot, add a product reveal after a UGC clip, or grow a take past its first render. Send `video_url` (1.625 to 60 seconds, up to 50 MB, MP4) and `prompt`. `duration_seconds` sets the new footage (5 to 15). `output` is `extended` (the source followed by the new footage, the default) or `continuation` (only the new footage). `aspect_ratio` `auto` keeps the source framing; another ratio crops to it. The new footage may run slightly longer than the requested seconds.

## Pricing
Unit: clip. Pricing key: `h3-max-extend`.

| request | credits |
|---|---|
| `5s_768p` | 5 |
| `10s_768p` | 10 |
| `15s_768p` | 15 |

Credits come from the roasOS pricing table (`MODEL_COSTS`) through the catalog. No other field changes the price.

## Modes
- `edit`
Provider endpoints: `minimax/h3-max/extend-video`.

## Request fields
| field | type | required | default | rule |
|---|---|---|---|---|
| `aspect_ratio` | enum | no | `16:9` | `auto`, `21:9`, `16:9`, `4:3`, `1:1`, `3:4`, `9:16` |
| `duration_seconds` | integer enum | no | `5` | `5`, `6`, `7`, `8`, `9`, `10`, `11`, `12`, `13`, `14`, `15` |
| `output` | enum | no | `extended` | `extended`, `continuation` |
| `prompt` | string | yes | — | ≥ 1 character; ≤ 10,000 characters |
| `quote_id` | string | no | — | UUID |
| `quote_only` | boolean | no | `false` | — |
| `resolution` | enum | no | `768p` | `480p`, `768p`, `1080p` |
| `seed` | integer | no | — | 0–2147483647 |
| `video_url` | string | yes | — | https URL; ≤ 4,096 characters |
| `wait_timeout_seconds` | integer | no | `0` | 0–60 |
| `webhook_url` | string | no | — | https URL; ≤ 4,096 characters |

The schema is strict: a field that is not in this table returns `400 unsupported_option`. Field names are the roasOS role names, one name per role across every family.

## Media
- `video_url` — the source video
- Refused: `avatar_id`, `elements`, `product_id`, `product_images`, `references`, `reference_images`, `image_url`, `end_image_url`, `scene_id`, `scene_image`, `video_urls`, `audio_urls`, `audio_url`, `voice_id`. A refused role returns `400 unsupported_option`.
- Every URL must be an immutable object on `https://cdn.roasos.com/…` that your workspace owns; any other URL is `400 reference_media_not_workspace_owned`. Upload with `POST /v1/uploads` (direct POST of the bytes to `put_url`, or a `source_url` import), then use the returned CDN URL.

## Prompt
Limit 10,000 characters.
- Describe the continuation, not the source. The model reads the source.
- Keep one action and one camera move, and say where the move ends.

## Not exposed
- `enable_prompt_expansion`: pinned to `provider default (on); never sent`.
- `enable_safety_checker`: pinned to `provider default (on); never sent`.
- `resolution`: pinned to `2K is not offered`.

## Result
Result kind `video`. Always present: `url`.
```json
{ "data": { "id": "gen_…", "kind": "video", "model": "h3-max-extend", "status": "completed", "result": {"url":"https://cdn.roasos.com/workspaces/ws_01/result"} } }
```
Files live on `https://cdn.roasos.com` and are immutable; a result URL can be a media input to the next call. Poll `GET /v1/jobs/{id}/status` → `{ id, status, updated_at }`, then `GET /v1/jobs/{id}/result` (`409 run_not_completed` until the job is `completed`, `failed` or `canceled`). Statuses: `queued → processing → completed | failed | canceled`.

## Example
```bash
# 1. quote — nothing is spent
curl -X POST https://api.roasos.com/v1/video/h3-max-extend \
  -H "Authorization: Bearer roasos_sk_live_…" \
  -H "Idempotency-Key: 0f1c9e2a-h3-max-extend-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_only":true,"prompt":"A woman holds the bottle at eye level in a bright kitchen, morning light, static camera.","video_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/video_url.mp4"}'
# → 200 { "data": { "kind": "quote", "quote_id": "q_7Hk…", "credits": 5, "expires_at": "…", "confirmation": { "model": "h3-max-extend", "example": "5s_768p" } } }

# 2. run — the same body and the same Idempotency-Key, quote_id instead of quote_only
curl -X POST https://api.roasos.com/v1/video/h3-max-extend \
  -H "Authorization: Bearer roasos_sk_live_…" \
  -H "Idempotency-Key: 0f1c9e2a-h3-max-extend-0001" \
  -H "Content-Type: application/json" \
  -d '{"quote_id":"q_7Hk…","prompt":"A woman holds the bottle at eye level in a bright kitchen, morning light, static camera.","video_url":"https://cdn.roasos.com/workspaces/ws_01/uploads/video_url.mp4"}'
# → 201 { "data": { "id": "gen_…", "kind": "video", "model": "h3-max-extend", "status": "queued", "credits_reserved": 5, "links": { "status": "/v1/jobs/gen_…/status", "result": "/v1/jobs/gen_…/result" } } }

# 3. poll
curl https://api.roasos.com/v1/jobs/gen_…/status -H "Authorization: Bearer roasos_sk_live_…"
curl https://api.roasos.com/v1/jobs/gen_…/result -H "Authorization: Bearer roasos_sk_live_…"
```

## Today
`POST /v1/video/h3-max-extend` with `video_url`, `prompt`, `duration_seconds` (5-15), `resolution` (480p|768p|1080p), `aspect_ratio` (auto or a ratio), `output` and `seed`.

## See also
https://docs.roasos.com/models/video/h3-max-extend · https://api.roasos.com/v1/catalog/video/h3-max-extend · minimax/h3-max/extend-video