I run a Passo-based mobile app alongside a separate web store. Today, when a customer fills a cart on the website and then opens the Passo app, the cart is empty. I want those same products to follow the user so they appear instantly on the app’s payment screen as soon as they sign in. Key points • Web store and app currently have no direct integration. • Users authenticate through OAuth, yet on the mobile side they still enter e-mail and password. • The goal is a seamless, real-time cart hand-off—no manual refreshes, no duplicate log-ins. What I need from you 1. Assess the existing web platform (custom, WordPress, Shopify, etc.) and propose the cleanest way to expose cart data—REST, GraphQL, or another approach that fits. 2. Build the service layer or middleware that captures a user’s active cart and associates it with their OAuth identity. 3. Update the Passo mobile app to pull that cart on login and display it on the payment screen. 4. Implement secure data flow, handle edge cases (guest checkout, item out of stock, cart updates), and provide end-to-end testing. 5. Deliver brief technical documentation so I can maintain the connection going forward. If you have experience integrating e-commerce back ends with mobile apps, especially around OAuth flows and real-time data sync, I’d love to see your approach and timeline.