# SwimBuddy

Swimming workout tracker with Apple Watch companion app. Expo 57 + React Native 0.86 + NativeWind v5 + Drizzle ORM + Swift Watch target.

## Commands

```bash
npx expo start              # Dev server
npx expo run:ios            # Build & run on iOS
npx expo prebuild -p ios    # Regenerate ios/ dir (safe — targets/ persists)
npx drizzle-kit generate    # Regenerate SQL migrations after schema changes
```

No `npm test` or lint scripts exist yet. No `babel.config.js` — NativeWind v5 uses CSS-first config.

## Project Structure

```
src/
  features/<name>/screens/   # Screen components (registered in navigators)
  features/<name>/components/# Feature-specific UI
  features/<name>/hooks/     # Feature-specific hooks
  components/                # Shared UI primitives (flat)
  hooks/                     # Shared hooks
  navigation/                # React Navigation (RootNav, TabNav, feature stacks)
  db/                        # Drizzle schema, client, relations, operations
  providers/                 # DatabaseProvider, SettingsProvider (MMKV)
  utils/                     # formatTime, calculateSwolf, uuid, etc.
  constants/                 # strokes, poolLengths, colors
  types/                     # workout.ts, common.ts
  modules/watch-connectivity/# Expo native module bridging WCSession
targets/watch/               # Apple Watch app (Swift/SwiftUI) — survives prebuild
```

## Key Conventions

- **Path aliases**: `@/`, `@features/`, `@components/`, `@db/`, etc. (tsconfig.json)
- **Feature-based** folder structure with **type-based** shared layer
- **NativeWind v5**: `className` prop, no babel config, CSS-first. Use `className` not `StyleSheet`
- **`className` types**: `nativewind-env.d.ts` at root — don't delete
- **lightningcss pinned** to 1.30.1 in package.json overrides — required by NativeWind v5

## Watch Target

- Lives in `targets/watch/`, NOT in `ios/` — survives `expo prebuild --clean`
- Config: `targets/watch/expo-target.config.js`
- Build: open `ios/SwimBuddy.xcworkspace` in Xcode, select Watch scheme
- Uses App Groups (`group.nl.guido-it.swimbuddy`) for data sharing
- WCSession for real-time messaging, `transferUserInfo` for reliable offline sync
- HealthKit for swim workout tracking (indoor swimming)
- Swift types `StoredWorkout`, `StoredSet`, `CompletedLap` in `WorkoutManager.swift`

## Database

- **expo-sqlite** + **Drizzle ORM** (SQLite dialect, expo driver)
- Schema: `src/db/schema.ts` — tables: templates, workouts, sets, laps
- Relations: `src/db/relations.ts`
- CRUD: `src/db/operations.ts`
- Client: `src/db/client.ts` — exports `db` and `DATABASE_NAME`
- Migrations in `drizzle/` — generated by `npx drizzle-kit generate`

## WCSession Gotchas (Critical)

These are hard-won bugs that will waste hours if rediscovered:

- **`NSNull` crashes `sendMessage`**: JS `null` becomes `NSNull` in ObjC, causing `WCErrorCodePayloadUnsupportedTypes` (Code 7010). Always strip `null`/`undefined` values before sending via `cleanForWCSession()`.
- **Two delegate methods conflict**: Having both `session(_:didReceiveMessage:)` AND `session(_:didReceiveMessage:replyHandler:)` on the same delegate causes iOS to deliver neither. Watch uses `didReceiveMessage` (no replyHandler); phone uses `didReceiveMessage:replyHandler:` for bidirectional sync.
- **`isReachable` is unreliable**: Only `true` when both apps are foreground. Check `session.activationState == .activated` instead for connection readiness.
- **Phone `sendMessage` must use `replyHandler: nil`**: Otherwise JS thread blocks waiting for a reply that watch never sends. Use fire-and-forget for workout plans; use `transferUserInfo` for data sync.
- **Watch `suiteName` vs `UserDefaults.standard`**: Watch only needs local storage, so use `UserDefaults.standard` — the App Groups suite name is only needed for phone↔watch shared data.
- **Phone `pendingEvents` polling**: Phone polls `pollEvents()` every 2s because Expo Modules' `sendEvent` API doesn't work on `AppContext`. Watch data arrives via `didReceiveUserInfo` delegate → stored in `pendingEvents` array.

## Watch ↔ Phone Data Flow

- **Phone → Watch**: `sendMessage` with workout plan (fire-and-forget, promise resolves immediately with `["status":"sent"]`)
- **Watch → Phone**: `transferUserInfo` with completed workout data (reliable, works in background)
- **Phone receives**: `pollEvents()` called from JS every 2s, `saveWatchCompletedWorkout()` writes to SQLite

## UI Conventions

- Swipe-to-delete on lists uses `SwipeableRow` component (`react-native-gesture-handler`)
- BuilderScreen pool length is a 25m/50m toggle (not read-only from settings)
- Templates and Stats features removed from navigation (DB schema preserved but UI deleted)
- Ionicons used for bottom tab icons (`@expo/vector-icons`)

## NativeWind v5 TextInput Crash

`react-native-css` has a bug where the `textAlign` mapping on `TextInput` causes a crash (`path.split` on boolean `true`). The fix is in `src/utils/` — don't remove the workaround without testing TextInput rendering.

## Gotchas

- `metro.config.js` has `.sql` in `sourceExts` — required for Drizzle migration imports
- `expo prebuild` clears and regenerates `ios/` by default. Use `--no-clean` to preserve
- Watch target compiles as separate Xcode target — not a RN module
- `react-native-css` is a NativeWind v5 peer dependency — don't remove
- `@bacons/apple-targets` plugin must be in app.json plugins array

## Expo Docs

Expo SDK 57: https://docs.expo.dev/versions/v57.0.0/