Use this request to include the extension information of a given shopping cart. The extension API should always work in tandem with a function.
Take the following scenario as an example:
Imagine there is a Drugstore selling controlled substances. In order to be able to place an order, whenever there is a controlled substance in the cart, the user must include a link with the medical prescription for that product. This will be a custom component of that store, and this component will use the Extensions API to include the data in the cart. This component will also raise an event that will trigger a function. This function will get the data from the extension and carry it forward to the ecommerce engine.
The cartId is the data structure that represents a shopping cart and contains all information pertaining to it. Hence, the cartId is the identification code of a given cart.
cartId is the equivalent of orderFormId for VTEX stores
The authentication of this endpoint can change depending on the customer context. If you are modifying information from a customer with a complete profile on the store, the response will return the customer's data masked. You can only access the customer data with an authenticated request.