XRPL Shopify Checkout Plugin Goal Build a Shopify app that enables users pay with XRPL tokens at checkout. On click, the app calls the backend to create a hosted payment link, opens it in a new tab, completes payment in RLUSD or USDC on XRPL, and auto-confirms the Shopify order when paid. Reference Functionally similar to Helio’s Solana Pay app, but for XRPL and an existing payments backend. Core Flow 1. Merchant installs the plugin from Shopify App Store. 2. App config: merchant pastes their API key and XRPL receiving address. 3. At checkout, buyer selects “Pay now”. 4. App requests a payment link from an API (amount, currency, order_id, return URLs). 5. New tab opens to a hosted checkout page. 6. Buyer pays RLUSD or USDC on XRPL via compatible wallet (e.g., Xaman). 7. Webhook → Shopify: verify on-chain payment, mark order paid, capture notes/tx hash. Scope - Shopify app (Payments/Checkout UI extension + Admin UI) - Secure merchant settings (API key, XRPL address) - Payment-link creation call to the an existing server - Webhook endpoint to accept payment confirmations and update Shopify order status - Error states, retries, and idempotency with order_id Must Support - Currencies: RLUSD and USDC on XRPL - Wallets: Xaman (XUMM) deep-link / QR; generic XRPL address+memo flow - Order reconciliation: store transaction hash, amount, currency, confirmations - PCI-safe pattern: no card data; only redirects + webhooks - App Store readiness: OAuth, billing-free (if not charging), GDPR/uninstall cleanup Deliverables - Public Shopify app submission-ready (listing assets, privacy page, scopes) - Source code (frontend + backend) with README - ENV-based config for API base URL and keys - Automated tests for webhook verification and order status updates - Minimal docs: install → configure → test → go-live Tech - Shopify App: Node/TypeScript, Remix/Next (App Bridge, Polaris), Checkout UI Extension - Backend: Node/TS (Express/Cloudflare Worker), webhook verification, HMAC signing - XRPL interaction handled by hosted checkout; app only orchestrates redirects/webhooks Acceptance Criteria - Install app, set API key + XRPL address, place test order, complete payment via the hosted page, Shopify order auto-moves to “Paid,” transaction hash stored in order timeline/notes - Handles cancel/expired payments without marking paid - Works with latest Shopify checkout extensibility