# Refresh Token

Obtain a new JWT access token using a refresh token.

**Endpoint**: `POST /api/auth/refresh`
**Auth**: Not required (uses refresh token)
**Content-Type**: `application/json`

## Request Body

| Field | Type | Required | Description |
|--------|------|-----------|-------------|
| refresh_token | string | Yes | Valid refresh token (UUID) |

### Example Request

```json
{
  "refresh_token": "d4f5g6h7..."
}
```

## Response (200 OK)

```json
{
  "access_token": "new-jwt-token",
  "token_type": "Bearer",
  "expires_in": 604800
}
```

**Session Duration**: 7 days (604800 seconds)

The new access token is valid for 7 days from the time of refresh.

## Error Responses

| Code | Description |
|------|-------------|
| 401 | Invalid or expired refresh token |
| 400 | Missing refresh token or invalid format |
