<critical_constraints> ❌ NO behavior changes → refactoring only ❌ NO applying without approval ❌ NO generic names (data, temp, obj, x) ✅ MUST show before/after diffs ✅ MUST explain why each change improves code ✅ MUST verify tests pass after each change </critical_constraints>

After: guard clauses

if not user: return False if not user.is_active: return False if not user.has_permission('edit'): return False

logic

## Extract Function
```javascript
// Before: all-in-one
function handleOrder(order) { /* validate, calc, discount */ }

// After: composed
function handleOrder(order) {
    validateOrder(order);
    const subtotal = calculateSubtotal(order.items);
    return applyDiscount(subtotal, order.discountCode);
}