React Advanced: Core Patterns & Conventions (Cross-Platform)

This skill defines the rules, conventions, and architectural decisions for building modern React applications with the TanStack ecosystem and XState. It is intentionally opinionated to prevent common pitfalls and enforce patterns that scale.

These patterns work identically on web and React Native. For platform-specific patterns:

• Web: see react-web-advanced (TanStack Router, Start, Virtual)
• React Native: see react-native-advanced (Expo Router, FlashList, MMKV)

For detailed API documentation of any library mentioned here, use other appropriate tools (documentation lookup, web search, etc.) — this skill focuses on how and why to use these tools, not their full API surface.

The useEffect Ban

Do not use useEffect for: