Quick Reference: React 19 + Next.js 15

# Quick Reference: React 19 + Next.js 15

## 🚨 Critical Rules

### 1. Always Use React 19 Patterns
```javascript
// ❌ OLD (React 18)
import { useFormState } from "react-dom";

// ✅ NEW (React 19)
import { useActionState } from "react";
```

### 2. Required next.config.js
```javascript
const nextConfig = {
  turbopack: {
    resolveAlias: {
      react: "react",
      "react-dom": "react-dom",
    },
    resolveExtensions: ['.ts', '.tsx', '.js', '.jsx', '.json'],
  },
};
```

### 3. Development Command
```bash
npm run dev  # Must use --turbo flag
```

## 🔧 Quick Fixes

### Form State Error
```javascript
// Replace this
const [state, formAction] = useFormState(action, initial);

// With this
const [state, formAction] = useActionState(action, initial);
```

### Turbopack Warning
Add to next.config.js:
```javascript
turbopack: { /* config above */ }
```

## 📦 Version Lock
```json
{
  "react": "^19.0.0",
  "react-dom": "^19.0.0", 
  "next": "^15.1.0"
}
```

---
💡 **Need help?** Check `docs/REACT_NEXTJS_COMPATIBILITY_RULES.md`