Hi. Recently our team created a custom shipping rates provider for our client (we created a shopify app and we're providing shipping rates endpoint for carrier service API).
But we have a struggle with changing shipping prices on changing order total price.
According to Shopify API Documentation, Shopify will use its' cache if none of these options are changed.
But what must we do if we want to make a free delivery if order total price is changed? Shopify uses cache and if user tried to select a shipment method, but then returned and added some more products to cart - Shopify will display him the same price.