# Nano Banana 2.1 (image)

> Nano Banana 2.1 makes and edits still images at low cost. It is the fast, high-volume member of the roasOS image family, best for iteration, large output sets and maskless edits.

Status: roasOS API v1.1. Catalog `model-catalog@2026-10-06.v5`, pricing `customer-pricing@2026-11-05.v15`. The endpoint `POST /v1/image/nano-banana-2.1` is live. `POST /v1/generations` stays for one minor version as a deprecated alias (see "Today").

## Endpoint
POST https://api.roasos.com/v1/image/nano-banana-2.1
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
Nano Banana 2.1 is Google's fast image generation and editing model. One 1K image costs 1 credit, against 2 for Nano Banana Pro. Use it to iterate on a concept, to make many variations, and to make a maskless edit of an existing image: send the source image as the only reference, state the change in the prompt, and set `aspect_ratio: "auto"` so the result keeps the source shape. It accepts the same identity, product and style roles as Nano Banana Pro. It does not do masked inpaint. Use Nano Banana Pro when the result is a final hero asset or when 4K output must hold fine detail.

## Pricing
Unit: image. Pricing key: `nano-banana-2.1`.

| request | credits |
|---|---|
| `1_image_1K` | 1 |
| `1_image_2K` | 2 |
| `1_image_4K` | 2 |
| `4_images_4K` | 8 |

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

## Modes
- `text-to-image`
- `edit`

The worker derives the mode from the media fields of the request.
Provider endpoints: `google/nano-banana-2.1` · `google/nano-banana-2.1/edit`.

## Request fields
| field | type | required | default | rule |
|---|---|---|---|---|
| `ad_look` | enum | no | — | `designed`, `native`, `ui` |
| `ad_set` | object | no | — | `{ id, index, total }` |
| `alter` | object | no | — | `{ mode, who, new_person, clothes, outfit, object, product, keep, multi_shot }` |
| `aspect_ratio` | enum | no | `1:1` | `auto`, `9:16`, `1:1`, `3:4`, `4:3`, `16:9`, `21:9` |
| `avatar_id` | string | no | — | UUID |
| `avatar_outfit` | string | no | — | ≤ 500 characters |
| `num_images` | integer | no | `1` | 1–4 |
| `product_id` | string | no | — | UUID |
| `product_images` | string[] | no | — | ≤ 14 items; only in `edit` |
| `prompt` | string | no | — | ≥ 1 character; ≤ 8,000 characters |
| `prompt_mode` | enum | no | — | `wrapped`, `exact` |
| `quote_id` | string | no | — | UUID |
| `quote_only` | boolean | no | `false` | — |
| `references` | string[] | no | — | ≤ 14 items; only in `edit` |
| `resolution` | enum | no | `1K` | `1K`, `2K`, `4K` |
| `seed` | integer | no | — | -2147483648–2147483647 |
| `source_image` | string | no | — | 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
- `avatar_id` — identity; the saved character reference sheet, with a derived portrait only where the model requires a single face or source frame
- `product_id` — product; resolves to the product image list
- `product_images` — product reference images
- `references` — style and appearance references

| role | items | max size | content types | duration |
|---|---|---|---|---|
| `product_images` | ≤ 14 | 10 MB | `image/jpeg`, `image/png`, `image/webp` | — |
| `references` | ≤ 14 | 10 MB | `image/jpeg`, `image/png`, `image/webp` | — |

- Refused: `elements`, `reference_images`, `image_url`, `end_image_url`, `scene_id`, `scene_image`, `video_urls`, `video_url`, `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: 8,000 characters for the caller; the wrapper counts toward the 10,000-character engine cap. No tag syntax; the worker orders the references and names the roles.
- Write one scene description with the camera, the light and the material named.
- For an edit, state the change only ("replace the sky with an overcast sky; keep everything else"), and set `aspect_ratio: "auto"`.
- Put identity and product rules in the media roles, not in the prompt text.
- Iterate here, then rerun the winning prompt on Nano Banana Pro for the final asset.
- Give rendered text inside quotation marks.

## Not exposed
- `output_format`: pinned to `png`.
- `safety_tolerance`: not accepted by this public endpoint.
- `enable_web_search`: pinned to `false`.
- `limit_generations`: pinned to `true`.
- `system_prompt`: not accepted by this public endpoint.
- `sync_mode`: not accepted by this public endpoint.
- `thinking_level`: not accepted by this public endpoint.
- `video_url`: not accepted by this public endpoint.
- `audio_url`: not accepted by this public endpoint.
- `pdf_url`: not accepted by this public endpoint.

## Result
Result kind `image`. Always present: nothing. Present when the run produces it: `avatar_id`, `full_body_url`, `images`, `portrait_url`, `provider_seed`, `reference_sheet`, `url`.
```json
{ "data": { "id": "gen_…", "kind": "image", "model": "nano-banana-2.1", "status": "completed", "result": {"avatar_id":"00000000-0000-4000-8000-000000000000","full_body_url":"https://cdn.roasos.com/workspaces/ws_01/full_body_url","images":["https://cdn.roasos.com/workspaces/ws_01/images-1.png"],"portrait_url":"https://cdn.roasos.com/workspaces/ws_01/portrait_url","provider_seed":0,"reference_sheet":"https://cdn.roasos.com/workspaces/ws_01/reference_sheet","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/image/nano-banana-2.1 \
  -H "Authorization: Bearer roasos_sk_live_…" \
  -H "Idempotency-Key: 0f1c9e2a-nano-banana-2.1-0001" \
  -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."}'
# → 200 { "data": { "kind": "quote", "quote_id": "q_7Hk…", "credits": 1, "expires_at": "…", "confirmation": { "model": "nano-banana-2.1", "example": "1_image_1K" } } }

# 2. run — the same body and the same Idempotency-Key, quote_id instead of quote_only
curl -X POST https://api.roasos.com/v1/image/nano-banana-2.1 \
  -H "Authorization: Bearer roasos_sk_live_…" \
  -H "Idempotency-Key: 0f1c9e2a-nano-banana-2.1-0001" \
  -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."}'
# → 201 { "data": { "id": "gen_…", "kind": "image", "model": "nano-banana-2.1", "status": "queued", "credits_reserved": 1, "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/generations `{ "type": "image", "model": "nano-banana-2.1", "prompt": "…", "options": { "aspect_ratio", "resolution", "num_outputs", "reference_images" (≤ 9), "seed" } }`. No `avatar_id`, `product_images` or `product_id` role today; the prompt is sent raw. The `resolution` values are `1K`, `2K` and `4K`. The default is `1K`. Today's `aspect_ratio` list is `auto, 9:16, 1:1, 3:4, 4:3, 16:9, 21:9`.

## See also
https://docs.roasos.com/models/image/nano-banana-2.1 · https://api.roasos.com/v1/catalog/image/nano-banana-2.1 · google/nano-banana-2.1 · google/nano-banana-2.1/edit