Search Existing Code Before Creating New Utilities

// components/rules/RuleCard.tsx
// ❌ Created a new date formatter without checking lib/utils/
function formatDate(date: string): string {
  const d = new Date(date)
  return `${d.getMonth() + 1}/${d.getDate()}/${d.getFullYear()}`
}
 
export function RuleCard({ rule }: { rule: Rule }) {
  return (
    <div>
      <h3>{rule.name}</h3>
      <span>Created: {formatDate(rule.createdAt)}</span>
    </div>
  )
}

// lib/utils/formatDate.ts (ALREADY EXISTS but was never found)
// This handles timezones, locales, and relative dates
export function formatDate(date: Date | string, options?: FormatOptions): string {
  const d = typeof date === 'string' ? new Date(date) : date
  return new Intl.DateTimeFormat('en-US', {
    month: 'short',
    day: 'numeric',
    year: 'numeric',
    ...options,
  }).format(d)
}
 
export function formatRelativeDate(date: Date | string): string {
  // Handles "2 hours ago", "yesterday", etc.
}

// lib/hooks/useDebounce.ts (file 1 — created by developer A)
export function useDebounce<T>(value: T, delay: number): T {
  const [debouncedValue, setDebouncedValue] = useState(value)
  useEffect(() => {
    const timer = setTimeout(() => setDebouncedValue(value), delay)
    return () => clearTimeout(timer)
  }, [value, delay])
  return debouncedValue
}
 
// lib/hooks/useDebouncedValue.ts (file 2 — created by developer B, same logic)
export function useDebouncedValue<T>(val: T, ms: number): T {
  // ❌ Identical implementation with different parameter names
}

// ✅ Before creating a new utility, run through this checklist:
 
// 1. Search lib/utils/ for existing utility functions
//    grep -rn "formatDate\|dateFormat\|format.*date" lib/utils/
 
// 2. Search lib/services/ for existing business logic
//    grep -rn "calculatePriority\|priority" lib/services/
 
// 3. Search components/ for existing UI patterns
//    grep -rn "Spinner\|Loading\|Skeleton" components/
 
// 4. Search lib/hooks/ for existing React hooks
//    grep -rn "useDebounce\|useDebouncedValue" lib/hooks/
 
// 5. Search lib/validation/ for existing Zod schemas
//    grep -rn "RuleSchema\|ruleSchema" lib/validation/
 
// 6. Search lib/types/ for existing type definitions
//    grep -rn "interface Rule " lib/types/ lib/domain/

// components/rules/RuleCard.tsx
// ✅ Found existing utility and used it
import { formatDate } from '@/lib/utils/formatDate'
 
export function RuleCard({ rule }: { rule: Rule }) {
  return (
    <div>
      <h3>{rule.name}</h3>
      <span>Created: {formatDate(rule.createdAt)}</span>
    </div>
  )
}

# Find potential duplicate utilities
grep -rn "export function format" src/lib --include="*.ts" -l
# Find duplicate hooks
grep -rn "export function use" src/lib/hooks --include="*.ts" -l
# Find duplicate type definitions for the same concept
grep -rn "interface.*Rule[^s]" src/ --include="*.ts"