API SpecsCartsUpdate cart line itemSets the quantity for a single product inside the active cart.PUT/api/unstable/carts/{handle}TestSets the quantity for a single product inside the active cart.Request Bodyapplication/jsondata*CartQuantityPayload[key: string]?neverResponse Body200application/json400application/json401403application/json404application/json409application/json422application/json503504application/jsonSubmit active cart POSTCreates an order from the current cart and returns the checkout URL.Catalog PublicCustomer-facing catalog metadata, access, and access request endpoints served through Effect HttpApi.