{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "CartItem",
  "description": "An item in the shopping cart.",
  "type": "object",
  "properties": {
    "productId": {
      "type": "string",
      "description": "Product SKU.",
      "example": "SKU-123456"
    },
    "quantity": {
      "type": "integer",
      "description": "Quantity.",
      "example": 2
    },
    "unitPrice": {
      "type": "number",
      "description": "Price per unit.",
      "example": 54.99
    }
  }
}