---
title: System One
---

# System One

`POST /v1/systemone`

The same decisions as [`/v1/decisions`](/docs/api-reference/decisions), in the System One request shape used by TypeSafe Jev and Cloudflare Clef. Use it if your code already speaks that shape; every decision model works on both endpoints.

## Endpoint

```http
POST https://api.crossmodel.ai/v1/systemone
Authorization: Bearer cm-YOUR_KEY
Content-Type: application/json
```

## Request

```json
{
  "model": "typesafe/jev",
  "state": "Help! My payouts have been failing for 3 days.",
  "questions": {
    "urgent": { "type": "noul", "instructions": "Does this message convey urgency?" },
    "team": {
      "type": "choice",
      "instructions": "Which team should handle this?",
      "criteria": { "billing": "Payments and payouts", "technical": null, "sales": null }
    },
    "frustration": {
      "type": "score",
      "instructions": "How frustrated is the customer?",
      "criteria": ["No sign of frustration", "Clearly unhappy", "Threatening to leave or complain"]
    }
  }
}
```

| Parameter | Type | Required | Notes |
|------|------|------|------|
| `model` | string | Yes | A decision model ID, e.g. `typesafe/jev`. |
| `state` | string, object or array | Yes | The content to decide about. An array may mix `{ "type": "text", "text" }` and `{ "type": "image_url", "image_url": { "url" } }` parts. |
| `images` | string[] | No | Image data URLs, appended after `state`. |
| `questions` | object | Yes | Questions keyed by name. The key order is the question order. |

Any other top-level field is rejected with `400 unknown_parameter`.

### Question types

| `type` | `criteria` | Answer |
|------|------|------|
| `noul` | Optional object with `true` and / or `false`: what each answer means. | `noul`: the probability that the answer is yes. |
| `choice` | Object whose keys are the options and whose values are descriptions (or `null`). | The chosen `choice`, a `confidence`, and a probability per option. |
| `score` | Array of level descriptions, lowest first. | A `score` (the expected level index, 0 to the number of levels minus 1), a `confidence`, a `legend`, and a probability per level. |

## Response

```json
{
  "model": "typesafe/jev",
  "answers": {
    "urgent": { "type": "noul", "noul": 0.97 },
    "team": {
      "type": "choice",
      "choice": "billing",
      "confidence": 0.91,
      "probabilities": { "billing": 0.93, "technical": 0.06, "sales": 0.01 }
    },
    "frustration": {
      "type": "score",
      "score": 1.42,
      "confidence": 0.64,
      "legend": {
        "0": "No sign of frustration",
        "1": "Clearly unhappy",
        "2": "Threatening to leave or complain"
      },
      "probabilities": { "0": 0.03, "1": 0.52, "2": 0.45 }
    }
  },
  "usage": { "input_tokens": 148, "output_tokens": 0 }
}
```

Answers are keyed by the same names as the questions. If a model declines one question, that answer is `{ "type": "refusal" }`, optionally with a `reason`.

## How the two shapes map

| `/v1/decisions` | `/v1/systemone` |
|------|------|
| `input` | `state` (plus `images`) |
| `questions` array with `name` | `questions` object keyed by name |
| `predicate` | `noul` |
| `choices[].value` / `description` | `criteria` keys / values |
| `levels[].label` / `description` | `criteria` array entries |
| `answers` array | `answers` object |
| `usage.total_tokens` | not present |

Billing and errors are the same as on [`/v1/decisions`](/docs/api-reference/decisions#billing).