laksh-ya/offpayapp — reverse-engineered prompt

Build me an Android app called OffPay that makes offline UPI payments over the *99# USSD service feel like a normal modern payments app. I want people to be able to send money to a UPI ID, enter an amount and note, scan a QR code with the camera or import one from the gallery, and check their bank balance, all without mobile data or WiFi, just a SIM with voice signal.

Please support two simple modes. Auto mode should handle the USSD flow inside a polished app experience using call permission, accessibility, and overlay. Manual mode should work on any Android phone by copying the UPI ID and opening the dialer with the right code filled in. If the phone is on Jio, the app should clearly say that *99# is not supported.

Keep it privacy first. No accounts, no ads, no servers, no tracking, and no outbound network calls after install. Keep the UPI PIN only in memory, and save a small encrypted on device payment history with payment details and a pay again option. A clean, bold UI with satisfying success and failure feedback would be great. Look up current Android docs if you need to.