From Concept to App Store: A Full-Featured Social App Built on React Native & Firebase

Achieving true runtime theme switching in React Native is non-trivial — StyleSheet.create() evaluates at module load time, before the user's stored preference is known, causing the wrong theme to persist on components until remount.

Designed a custom ThemeContext backed by AsyncStorage that mutates a shared color object in-place at startup and on every toggle. The root navigator remounts on theme change, ensuring every inline style and useMemo-computed stylesheet picks up the new palette instantly — with no flicker and no per-component subscription logic needed.

The app required a scalable chat layer — supporting both 1:1 and multi-participant threads — with unread count tracking, push delivery, and consistent message ordering, without introducing separate WebSocket infrastructure.

Architected the full messaging layer on Firestore's real-time listeners with a custom service managing thread creation, participant indexing, message pagination, and per-user unread counters. Firebase Cloud Functions handle FCM push delivery on message events, keeping the client stateless and the infrastructure fully serverless.

Users needed a secure, isolated storage area for sensitive media — requiring seamless integration of OS-level biometrics with a custom PIN entry and recovery flow, without exposing vault state to the main navigation.

Implemented a layered vault access system using FaceID/TouchID via react-native-biometrics with a graceful PIN fallback and a separate account-recovery flow. Vault navigation is isolated from the main stack and gated at the route level, so vault content is never accessible through standard navigation paths.