You're tasked with debugging and enhancing an existing Android application developed for government exam preparation (e.g., SSC, UPSC, Banking). The app includes key features like user authentication, mock tests, push notifications, real-time chat, and score analysis. Your role is to fix critical issues on both the frontend (Android app built in Kotlin) and backend (mongodb), ensuring smooth user login, functional mock test navigation, accurate test submissions, reliable push notifications via FCM, and stable real-time chat. You'll receive the current APK, source code, API documentation, and a list of bugs to address. Deliverables include a working, tested APK, updated source code, and a changelog of fixes. Skills in debugging, REST API integration, Firebase services, and Android architecture (MVVM preferred) are essential. Bonus points for improving app performance, adding crash reporting, or writing basic tests. The goal is to make the app production-ready within 3–5 days for internal testing and stakeholder review.