My multi-app food-delivery platform (React Native front ends, Java & Spring Boot backend) already runs smoothly for customers, restaurants, delivery partners and admins. I now need a secure hand-over confirmation flow: 1. When the order is marked “out for delivery”, the Customer app must auto-generate a single-use OTP/Pin. 2. The code stays valid for exactly 30 minutes (time-based expiry) and the customer can trigger a fresh code immediately if something goes wrong. 3. The Delivery Partner app prompts for this code on arrival; on successful match the backend records “delivered” and releases any pending status updates to the Restaurant and Admin apps. Technical notes • React Native (Android only) with Java modules is the current stack; server side is Spring Boot with MySQL. • Please respect Google’s 16-kB native library alignment requirement throughout the build—even though I am distributing via direct APK sideload, not Play Store. • No other features are changing, so keep the existing architecture and naming conventions intact. Deliverables • Updated source code for Customer, Delivery Partner and backend modules. • Signed, install-ready APKs for the two affected mobile apps. • Brief setup notes so my team can reproduce the build. Acceptance I will run a test order: the Customer app must display a fresh 6-digit code, allow an immediate re-generate, time out at 10 minutes, and sync correctly with the Delivery Partner app and backend logs.