{
  "data": {
    "id": "cst_101",
    "name": "Alice Johnson",
    "first_name": "Alice",
    "last_name": "Johnson",
    "email": "alice@example.com",
    "phone_number": "+15552345678",
    "custom_attributes": {
      "plan": "Enterprise",
      "mrr": 499
    },
    "created_at": "2026-08-10T14:00:00Z"
  }
}