Varunsingh7389/MeshPay-Offline-UPI-Payments-over-Mesh ? reverse-engineered prompt

Build me a Spring Boot web app that simulates UPI payments working without internet, where a payment starts on one phone, gets encrypted, hops through nearby devices in a mesh style relay, and finally reaches a bridge node that can upload it to the server later.

I want a simple dashboard where I can create a payment, inject it into the mesh, run gossip rounds, and watch the packet move between devices until it settles. Show account balances, a transaction ledger, and an activity log so I can see what happened at each step. Make the server reject duplicate submissions, ignore old packets, and only settle a payment once even if multiple bridges try to upload it at the same time.

Use an H2 database, keep the crypto handled on the backend, and make the whole thing feel like a clear demo of how secure offline payments could work. If you need to check anything, look up current Spring Boot docs online.