General React & React Native Patterns

_These rules apply to all files, including those inside src/mvvm/. See mvvm-architecture for MVVM-specific structure._

Component Architecture

• Prefer functional components.
• Keep components focused and reasonably sized.
• Decompose large UI into smaller reusable elements.
• Use composition for extensibility.

State Management

• Prioritize local state for UI-only concerns.
• Use RTK Query (with slices) only when necessary for app-wide state. See rtk-query-api.
• Apply optimized selectors to limit re-rendering.
• Connect Redux at the lowest component level when possible.

Styling

• Mobile: use Lumen UI React Native — see ldls-native.
• Desktop: use Lumen UI React — see ldls-web.
• All styles must support theme switching (dark/light mode).

Performance

• Memoize expensive operations with useMemo.
• Stabilize callbacks with useCallback.
• Wrap costly components in React.memo.
• Apply list virtualization where needed.
• Use lazy loading for large screens or modules.

Navigation

• Mobile: use React Navigation; ensure correct deep-link support; keep navigation types strict.
• Desktop: use React Router; implement route guards when necessary; maintain clear history logic.

Data Fetching

• Use RTK Query. See rtk-query-api.
• Use consistent loading, retry, and error states.
• Prefer optimistic UI when appropriate.
• Apply caching and stale-time strategies.

Accessibility

• Mobile: provide accessible labels for all interactive elements; support screen reader flows; ensure proper focus transitions.
• Desktop: use semantic HTML tags; implement full keyboard navigation; apply meaningful ARIA attributes when required.

Error Boundaries

• Wrap critical areas in error boundaries.
• Report errors to monitoring services.
• Provide clean, user-friendly fallback UIs.

Platform-Specific Code

• React Native: use Platform.select for small platform variations; ensure behavior parity across iOS and Android.
• Desktop: use environment flags for Electron/Web differences; keep platform abstraction consistent.

Animations

• Mobile: use the native driver whenever feasible; prefer Animated and layout animations for performance.
• Desktop: use CSS transitions for lightweight animations; use Framer Motion for complex animations; respect reduced-motion system preferences.

Internationalization (i18n)

• Use react-i18next consistently.
• Keep translation keys descriptive and structured.
• Support pluralization, gender, and variable interpolation.
• Validate components across multiple locales.