Lead React Native Engineer

Responsibilities:

• Offline-first architecture - complete the WatermelonDB transition. Design the sync strategy, conflict resolution logic, and local schema that supports the full member data model. Make the app feel instant on 2G in a Tier-3 city.
• Wearable abstraction layer - design a unified internal API that the RN layer uses to consume health data regardless of source. Own the Terra integration. Build and own direct native module integrations as new wearables come into scope.
• Native module ownership - HealthKit, wearable SDKs, background sync, push notification handling. You are comfortable in Swift and Kotlin enough to build and debug native modules when the JS bridge is insufficient.
• Performance and reliability - app startup time, background task management, battery impact of sync operations, crash rate. These metrics are yours to own.
• Technical direction for a team of three - one SDE-2 and two SDE-1s. You set the code quality bar, run reviews, make the architectural calls, and grow the engineers under you.
• Roadmap input - as we expand the app to serve doctors and nutritionists on mobile in future, you will be in the room where those product decisions are made. Your technical judgment shapes what is possible.
• The stack: React Native, WatermelonDB, MMKV, Terra API, Apple HealthKit, WHOOP SDK, Oura API, Swift / Kotlin (native modules), FastAPI backend, Supabase / PostgreSQL, GCP
• The app is cross-platform iOS and Android. iOS is primary - most of our members are on iOS, and the wearable ecosystem is richer there. Android parity is important and maintained.

Requirements:

• You have shipped a production React Native app that real people use daily, dealt with the offline scenarios, the background sync edge cases, the iOS version fragmentation, and the native module debugging that no Stack Overflow answer covers. You have scar tissue.
• You think about mobile architecture the way a backend engineer thinks about distributed systems - with respect for failure modes, eventual consistency, and the consequences of getting sync wrong on someone's health data.
• You are comfortable owning a problem completely. Not "I implemented the feature. You designed it, built it, debugged it in production, monitored it, and iterated on it when it was not good enough.
• 6-8 years of mobile engineering, with meaningful React Native production experience.
• Offline-first experience - WatermelonDB, Realm, or equivalent. You understand sync conflict strategies and have implemented at least one in production.
• Native module experience - Swift or Kotlin, ideally both. You have bridged a native SDK to RN and debugged it across OS versions.
• Wearable or health data integration - Apple HealthKit, Google Fit, or direct device SDK experience. Understanding of background fetch, workout sessions, and sensor data reliability.
• Strong TypeScript discipline. The codebase you maintain will be read by engineers less experienced than you. Types are documentation.
• Enough backend literacy to understand a sync protocol, read a PostgreSQL schema, and debug a data inconsistency without needing a backend engineer to hold your hand.

Green flags:

• You have dealt with Terra, HealthKit aggregation, or multi-source health data normalisation and know exactly where the sharp edges are.
• You have a strong opinion about the right WatermelonDB schema design for a health data model and can defend it.
• You have worked at a startup where you were the only or primary mobile engineer and made decisions with no safety net.
• You have personal interest in longevity, wearables, or quantified self. You use the kind of products you would be building.
• You have thought about what offline-first means for health data specifically - where eventual consistency is acceptable and where it is not.