{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "CartItemInput",
  "description": "Request to add an item to the cart.",
  "type": "object",
  "required": [
    "productId",
    "quantity"
  ],
  "properties": {
    "productId": {
      "type": "string",
      "description": "Product SKU to add.",
      "example": "SKU-123456"
    },
    "quantity": {
      "type": "integer",
      "description": "Quantity to add.",
      "example": 2
    }
  }
}