Backend Shopify developer Offline

We’re looking for an experienced Shopify developer to help us resolve a cart drawer discount code issue on our Shopify store 

The Goal
We need discount codes to:
• Be applied directly in the cart drawer and passed seamlessly to checkout
• Support complex types (BOGO, minimum cart value, percentage off, etc.)
• Show custom error messages if the discount conditions aren’t met
• Auto-apply from URLs (e.g., promo or affiliate links)
The previous method we used relied on a now-deprecated endpoint (wallets/checkout). We believe the Storefront API’s cartDiscountCodesUpdate mutation will likely be the replacement, but we’re open to whatever approach you believe is best.
What’s Required
• Rebuild or adjust the cart + checkout integration to work with Shopify’s current supported methods
• Ensure discount logic works correctly across all conditions
• Add support for custom error messages per code
• Ensure discount links with embedded codes work as expected
• Deploy changes to a staging theme for testing before going live
We’d like to work with someone who has done similar work and who is confident navigating Shopify’s discount logic and Storefront API.