carry-your-live/plan.md

Expo (React Native) + WatermelonDB Aspect Why Platforms Single codebase → iOS, Android, Web (Expo for Web) Offline-first WatermelonDB is built for this - local SQLite, reactive queries, lazy loading Sync Custom sync adapter to your Postgres API (REST/GraphQL) Team fit React/TypeScript native UI Matches your spec (React Native components, Reanimated for animations) Alternative: Expo + PowerSync

• Newer, SQL-based local DB with built-in sync protocol
• Handles conflict resolution, partial replication
• Requires PowerSync service (self-hosted or cloud) between app and your Postgres Architecture Overview ┌─────────────┐ ┌──────────────┐ ┌─────────────┐ │ Expo App │────▶│ WatermelonDB │────▶│ Your API │ │ (iOS/Android│ │ (SQLite) │ │ (Postgres) │ │ Web) │◀───▶│ + Sync │◀───▶│ │ └─────────────┘ └──────────────┘ └─────────────┘ Key Libraries
• Navigation: Expo Router (file-based, works on web)
• State: WatermelonDB (no Redux needed - DB is source of truth)
• UI: React Native Paper or Tamagui (cross-platform components)
• Date/Time: @react-native-community/datetimepicker + date-fns
• Forms: React Hook Form + Zod validation Sync Strategy (Custom API)

1. WatermelonDB synchronize() pulls changes since last sync token
2. Your API exposes /sync endpoint accepting lastPulledAt cursor
3. Returns { changes: [...], serverTimestamp }
4. Push local changes via /sync/push batch endpoint
5. Handle conflicts: last-write-wins or user resolution