nextjs15-performance

---

name: nextjs15-performance description: Next.js 15 critical performance fixes. Use when writing React components, data fetching, Server Actions, or optimizing bundle size.

Before writing Next.js code:

1. Read docs/agent/architecture/nextjs-critical-fixes.md for full patterns
2. Check existing components in apps/frontend/components/ for examples

Critical Rules (always apply):

Waterfalls

• Use Promise.all() for independent fetches
• Wrap slow data in <Suspense> boundaries
• Defer await into branches where needed

Bundle Size

• NO barrel imports: import X from 'lucide-react' ❌
• YES direct imports: import X from 'lucide-react/dist/esm/icons/x' ✅
• Use next/dynamic for heavy components (editors, charts, PDF viewers)
• Defer analytics with ssr: false

Server Actions

• ALWAYS check auth INSIDE the action, not just middleware
• Verify resource ownership before mutations

Production Build

• Users run npm run build && npm run start, NOT npm run dev
• Docker must use standalone output, not dev mode

Quick Check Before PR:

[ ] No sequential awaits for independent data
[ ] Icons imported directly
[ ] Heavy components use next/dynamic
[ ] Server Actions have auth inside
[ ] Suspense around slow fetches