# Evaluate named Choice, Noul and Score questions
Purpose: API operation reference for `POST /v1/systemone`.
Last updated: 2026-09-15

## Endpoint

```txt
POST /v1/systemone
```

## Description

Forward named questions and preserve the native answer, probabilities and usage.

## Request body

Content type: `application/json`

| Field | Required | Type | Description |
| --- | --- | --- | --- |
| `model` | Yes | `string` | model name to route to (may be an alias; rejected if blank) |
| `state` | Yes | `string \| object \| array<any>` | evidence shared by the questions |
| `questions` | Yes | `Questions` | caller question IDs mapped to structured questions |
| `input_audio` | No | `SystemOneInputMedia \| null` | optional inline audio evidence |
| `input_image` | No | `SystemOneInputMedia \| null` | optional inline image evidence |
| `input_video` | No | `SystemOneInputMedia \| null` | optional inline video evidence |

## Success response

Status: `200`
Content type: `application/json`

## Error responses

| Status | Description |
| --- | --- |
| `400` | The request was malformed, or a field value was invalid. |
| `401` | Missing, invalid, or expired credentials. |
| `402` | The account is out of credit. |
| `403` | Authenticated, but not a member of the requested organization. |
| `404` | The requested model does not exist or is not available. |
| `413` | The request body, or an inline media part, exceeds the accepted size. |
| `429` | Rate limit exceeded. |
| `500` | The model backend, or the gateway itself, failed while serving the request. |
| `502` | The model backend answered with something the gateway could not serve. |
| `503` | Temporarily unavailable; retry after `Retry-After` when present. |
| `504` | The model backend did not respond in time. |

## Related links

- [Markdown reference](https://sprag.ai/docs/api/systemone.md)
- [OpenAPI spec](https://sprag.ai/openapi.json)
- [Authentication](https://sprag.ai/docs/authentication.md)
- [Errors](https://sprag.ai/docs/errors.md)