# Add a person to a layer

`POST https://evohub.io/api/v1/schedules/{id}/layers/{layerID}/rotations`

Part of the [On-Call API](https://docs-dev.evohub.io/oncall.md) reference · operationId `addScheduleRotation`.

Adds a person to the layer's rota at `position` (0 is first); without
`position` they go to the end. The person must be a member of the
organization who can respond to alerts.

**Permission (API-key scope):** `oncall:schedule:write`.

## Authorization

Any one of:

- `bearerAuth` (oncall:schedule:write)
- `apiKeyHeader` (oncall:schedule:write)

Where:

- `bearerAuth`: HTTP Bearer — An EvoHub API key (`evohub_…`) as a bearer token.
- `apiKeyHeader`: API key in the header `X-API-Key` — An EvoHub API key (`evohub_…`).

## Path parameters

- `id` (string, required, example `5b1c7d2e-8f3a-4b9c-a0d1-e2f3a4b5c6d7`): The schedule's id.
- `layerID` (string, required, example `7c3d9e1f-2a4b-4c6d-8e0f-1a2b3c4d5e6f`): The layer's id. It must belong to the schedule in the path.

## Request body (required)

Content type: `application/json`

Type: `object`

- `user_id` (string, required)
- `position` (integer, min 0): 0-based place in the rota; the end when omitted.

## Responses

### 201 — The rota slot.

Content type: `application/json`

Type: `object`

- `data` (ScheduleRotation, required)
  - `id` (string)
  - `layer_id` (string)
  - `user_id` (string)
  - `position` (integer): 0-based place in the rota.
  - `created_at` (string (date-time))
- `success` (boolean, required, value `true`)

### 400 — The body is not JSON (`INVALID_BODY`) or `user_id` is empty (`VALIDATION_FAILED`).

Content type: `application/json`

Type: `ValidationError`

- `error` (object, required)
  - `code` (string, required, value `VALIDATION_FAILED`)
  - `message` (string, required)
  - `details` (array of object, required)
    - `field` (string)
    - `message` (string)

### 401 — No API key was sent, or it is unknown, revoked or expired (`UNAUTHORIZED`).

Content type: `application/json`

Type: `Error`

- `error` (object, required)
  - `code` (string, required): Machine-readable code. Branch on this.
  - `message` (string, required): Human-readable explanation.

### 403 — The key lacks the scope this endpoint needs (`FORBIDDEN`).

Content type: `application/json`

Type: `Error`

- `error` (object, required)
  - `code` (string, required): Machine-readable code. Branch on this.
  - `message` (string, required): Human-readable explanation.

### 404 — No such schedule or layer (`NOT_FOUND`), or the person is not a member of the organization (`NOT_A_MEMBER`).

Content type: `application/json`

Type: `Error`

- `error` (object, required)
  - `code` (string, required): Machine-readable code. Branch on this.
  - `message` (string, required): Human-readable explanation.

### 422 — The person cannot respond to alerts: they do not hold `oncall:alert:respond` (`CANNOT_RESPOND`).

Content type: `application/json`

Type: `Error`

- `error` (object, required)
  - `code` (string, required): Machine-readable code. Branch on this.
  - `message` (string, required): Human-readable explanation.

### 429 — Too many requests (`RATE_LIMITED`). Wait `Retry-After` seconds.

Headers:

- `Retry-After` (integer): Seconds to wait.

Content type: `application/json`

Type: `Error`

- `error` (object, required)
  - `code` (string, required): Machine-readable code. Branch on this.
  - `message` (string, required): Human-readable explanation.

### 500 — Something went wrong on EvoHub's side (`INTERNAL_ERROR`). Retry later.

Content type: `application/json`

Type: `Error`

- `error` (object, required)
  - `code` (string, required): Machine-readable code. Branch on this.
  - `message` (string, required): Human-readable explanation.

### 503 — Whether the person may be paged could not be checked right now; nothing was changed (`MEMBER_CHECK_UNAVAILABLE`). Retry shortly.

Content type: `application/json`

Type: `Error`

- `error` (object, required)
  - `code` (string, required): Machine-readable code. Branch on this.
  - `message` (string, required): Human-readable explanation.

## Example request

```bash
curl -X POST 'https://evohub.io/api/v1/schedules/5b1c7d2e-8f3a-4b9c-a0d1-e2f3a4b5c6d7/layers/7c3d9e1f-2a4b-4c6d-8e0f-1a2b3c4d5e6f/rotations' \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer <TOKEN>' \
  -d '{
  "user_id": "4c2a9e7b-1d3f-4a8c-b6e5-9f0a1b2c3d4e"
}'
```