React Patterns

React and Next.js performance optimization — curated rules across priority categories drawn from framework docs and production practice.

Complements mk:typescript (type safety) and mk:vue (Vue patterns). This skill covers React-specific performance patterns.

When to Use

• Writing or reviewing React/Next.js components
• Optimizing bundle size or render performance
• Fixing re-render issues
• Server vs client component decisions
• Data fetching patterns

Rule Categories (by priority)

Load the relevant reference when working in that area:

Priority	Category	Reference	Key rules
CRITICAL	Eliminating waterfalls	references/async-patterns.md	Defer await, parallel promises, Suspense boundaries
CRITICAL	Bundle size	references/bundle-optimization.md	No barrel imports, dynamic imports, defer third-party
HIGH	Server performance	references/server-patterns.md	React.cache(), LRU cache, parallel fetching, after()
MEDIUM	Re-render optimization	references/rerender-optimization.md	Derived state, functional setState, memo, transitions
MEDIUM	Rendering perf	references/rendering-patterns.md	content-visibility, hoist JSX, conditional render

Process

1. Identify the performance concern (waterfall? bundle? re-render? server?)
2. Load the matching reference file
3. Apply rules — each rule has: problem, solution, code example
4. Verify improvement (Lighthouse, bundle analyzer, React DevTools)

Gotchas

• Premature optimization: optimizing re-renders before measuring → measure first with React DevTools Profiler
• Over-memoizing: wrapping everything in useMemo/React.memo → memo only when profiler shows expensive re-renders
• Barrel file trap: importing from index.ts pulls entire module → always import directly from source file

Workflow Integration

Auto-activates during Phase 3 (Build) when React/Next.js project detected. Loaded by developer agent alongside mk:typescript.