mutation addConfigurableProductToCart(
  $cartId: String!
  $quantity: Float!
  $sku: String!
  $parentSku: String!
) {
  addConfigurableProductsToCart(
    input: {
      cart_id: $cartId
      cart_items: [
        { data: { quantity: $quantity, sku: $sku }, parent_sku: $parentSku }
      ]
    }
  ) {
    cart {
      id
      items {
        id
        product {
          id
          name
          sku
        }
        quantity
      }
    }
  }
}