🔄 Development Workflow SKILL

Purpose

Provide MECE (Mutually Exclusive, Collectively Exhaustive) todo template for all development tasks. Ensures code quality, type safety, and comprehensive validation before commit.

Auto-Trigger Conditions

Activate when:

1. Development tasks:

   • API development
   • New features
   • Refactoring
   • Bug fixes

2. User mentions keywords:

   • "개발", "API", "코드 작성"
   • "구현", "만들어줘"
   • "요구사항", "schema"

3. Before implementation:

   • After user clarifies requirements
   • Before writing first line of code
   • When starting new branch

📋 MECE Todo Template (5 Phases)

Phase 1: Requirements Analysis

Goal: Clearly define what to build

• Clarify User Story

  • Who: User persona
  • What: Feature description
  • Why: Business value

• Define Edge Cases

  • Empty value handling (null, undefined, empty string)
  • Error scenarios (network failure, timeout)
  • Boundary values (min/max, 0, negative numbers)

• Set Success Criteria

  • How to verify functionality
  • Performance goals (response time, throughput)
  • Compatibility requirements (browsers, devices)

Phase 2: Design

Goal: Design the structure for implementation

• Schema Analysis

  • Reference: @docs/claude/test.guide.md (test guide)
  • Verify database schema
  • Define API request/response formats
  • State management structure (Zustand, Redux)

• Type Definitions (TypeScript strict mode)

  • ❌ NEVER use any (Rule: Type safety is top priority)
  • ✅ ALWAYS use:
    • Utility types (Partial, Pick, Omit, Record)
    • Generic types (<T>, <K extends keyof T>)
    • Duck typing (structural typing)
    • Union types (string | number)
    • Discriminated unions (type guards)

  Example:

  typescriptCopy

  // ❌ BAD
  function process(data: any) { ... }
  
  // ✅ GOOD
  function process<T extends { id: string }>(data: T): Result<T> { ... }
  

• API Interface Design

  • Define REST endpoints (GET, POST, PUT, DELETE)
  • Request/Response types
  • Error handling structure
  • Validation rules

Phase 3: Implementation

Goal: Convert design into code

• Code Structuring (logically coherent)

  • Single Responsibility Principle (SRP): One role per function
  • DRY: Eliminate duplicate code
  • Function length: Maximum 50 lines (reduce complexity)
  • Readability: Clear variable names, minimal comments (code explains itself)

  Folder structure:

  Copy

  app/api/[endpoint]/
    route.ts           # API handler
    schema.ts          # Zod validation
    service.ts         # Business logic
    types.ts           # TypeScript types
  

• Follow Conventions (CLAUDE.md Lines 429-455)

  • PascalCase: Components, Types
  • camelCase: Functions, variables
  • UPPER_SNAKE_CASE: Constants
  • kebab-case: File names (URL slugs)
  • Tailwind: Utility-first CSS
  • Server-first: Next.js RSC pattern

• Write E2E Tests (testing-checklist-SKILL.md)

  • Reference: @docs/claude/test.guide.md
  • Happy path: Normal operation scenarios
  • Sad path: Error handling scenarios
  • Edge cases: Boundary values, empty values

  E2E Test Template:

  typescriptCopy

  // tests/e2e/api-endpoint.spec.ts
  test('should create item successfully', async ({ request }) => {
    const response = await request.post('/api/items', {
      data: { name: 'Test Item' }
    });
    expect(response.status()).toBe(201);
    const data = await response.json();
    expect(data).toHaveProperty('id');
  });
  
  test('should handle validation errors', async ({ request }) => {
    const response = await request.post('/api/items', {
      data: { name: '' } // Invalid: empty name
    });
    expect(response.status()).toBe(400);
  });
  

Phase 4: Validation

Goal: Ensure code quality + performance

• Run E2E Logic and Fix Errors

  bashCopy

  npx playwright test                    # Run all E2E tests
  npx playwright test --headed           # Visual debugging
  npx playwright test -g "API endpoint"  # Specific test
  

  Pass criteria:

  • All tests green ✅
  • Coverage: 80%+ for core logic
  • No flaky tests (remove unstable tests)

• Check and Fix any Types

  bashCopy

  # Search for 'any' type usage
  grep -r "any" app/ components/ lib/ --include="*.ts" --include="*.tsx"
  
  # Or use ESLint rule
  # "@typescript-eslint/no-explicit-any": "error"
  

  Fix methods:

  typescriptCopy

  // Before: using any
  function handleData(data: any) { ... }
  
  // After 1: Generic type
  function handleData<T extends Record<string, unknown>>(data: T) { ... }
  
  // After 2: Union type
  function handleData(data: string | number | boolean) { ... }
  
  // After 3: Interface definition
  interface DataStructure { id: string; value: number; }
  function handleData(data: DataStructure) { ... }
  

• Pessimistic Code Review (performance + quality)

  Checklist:

  1. Performance Optimization

     • No N+1 queries (database)
     • No unnecessary re-renders (React)
     • Apply memoization (useMemo, useCallback)
     • Image optimization (Next.js Image)
     • Check bundle size (npm run build → .next/analyze)

  2. Security (secure-coding-SKILL.md)

     • Prevent XSS (sanitize inputs)
     • Prevent SQL Injection (Prepared statements)
     • CSRF token verification
     • No sensitive info logging (passwords, API keys)

  3. Error Handling

     • Try-catch implementation
     • User-friendly error messages
     • Structured logging (Sentry, Winston)
     • Fallback UI (error boundaries)

  4. Accessibility (a11y)

     • Semantic HTML (header, nav, main)
     • ARIA labels (button, input)
     • Keyboard navigation (Tab, Enter)
     • Color contrast (WCAG AA standard)

• Run npm run lint

  bashCopy

  npm run lint        # ESLint + Prettier
  npm run type-check  # TypeScript errors
  

  Pass criteria:

  • 0 errors, 0 warnings
  • Auto-fix: npm run lint -- --fix

Phase 5: Deployment Preparation

Goal: Prepare for production environment

• Add Controller Exception Headers

  typescriptCopy

  // app/api/[endpoint]/route.ts
  export async function POST(request: Request) {
    try {
      // ... business logic
    } catch (error) {
      console.error('[API Error]', error);
      return NextResponse.json(
        { error: 'Internal Server Error' },
        {
          status: 500,
          headers: {
            'X-Error-Type': error instanceof Error ? error.name : 'Unknown',
            'X-Request-ID': crypto.randomUUID(), // For debugging
          }
        }
      );
    }
  }
  

• Pass Type-check

  bashCopy

  npm run type-check  # Must pass before commit
  

• Build Verification (when modifying Protected Files)

  bashCopy

  npm run build       # Production build
  # Check: No errors, bundle size acceptable
  

  Conditional Build (Rule 21):

  • Simple (1-2 files): type-check only
  • Important (Protected/3+files/core): type-check + build

• Commit (git-workflow)

  • Reference: .skills/git-workflow/commit-reminder-SKILL.md
  • Format: <Type>_<AI>_<Purpose>_<FileCount>-Files
  • Pre-commit hook: automatic type-check
  • NEVER auto-commit (Rule 2)

🔗 Integration with Other SKILLs

Workflow Integration

development-workflow (Phase 1-2)
   ↓
[User approves design]
   ↓
development-workflow (Phase 3: Implementation)
   ↓
testing-checklist-SKILL.md (E2E tests)
   ↓
development-workflow (Phase 4: Validation)
   ↓
secure-coding-SKILL.md (Security review)
   ↓
development-workflow (Phase 5: Deployment prep)
   ↓
git-workflow (Commit + Push)

File Relationships

📊 Quality Metrics

Phase Completion Criteria

Code Quality Checklist

• Cyclomatic Complexity < 10 (per function)
• Function length < 50 lines
• File length < 300 lines (split if larger)
• No commented-out code
• No console.log in production code
• No hardcoded values (use constants/env vars)

💡 Best Practices

Type Safety Patterns

1. Utility Types

// Pick specific properties
type UserProfile = Pick<User, 'name' | 'email'>;

// Make all properties optional
type PartialUser = Partial<User>;

// Omit sensitive fields
type PublicUser = Omit<User, 'password' | 'apiKey'>;

// Create key-value map
type StatusMap = Record<string, boolean>;

2. Generics

// Generic function
function findById<T extends { id: string }>(items: T[], id: string): T | undefined {
  return items.find(item => item.id === id);
}

// Generic component
interface TableProps<T> {
  data: T[];
  columns: Array<keyof T>;
}
function Table<T>({ data, columns }: TableProps<T>) { ... }

3. Type Guards

function isString(value: unknown): value is string {
  return typeof value === 'string';
}

function processValue(value: string | number) {
  if (isString(value)) {
    return value.toUpperCase(); // TypeScript knows value is string
  }
  return value.toFixed(2); // TypeScript knows value is number
}

E2E Test Patterns

1. API Testing

test.describe('POST /api/users', () => {
  test('should create user with valid data', async ({ request }) => {
    const response = await request.post('/api/users', {
      data: { name: 'John', email: '[email protected]' }
    });
    expect(response.ok()).toBeTruthy();
    const user = await response.json();
    expect(user).toMatchObject({ name: 'John', email: '[email protected]' });
  });

  test('should reject invalid email', async ({ request }) => {
    const response = await request.post('/api/users', {
      data: { name: 'John', email: 'invalid-email' }
    });
    expect(response.status()).toBe(400);
  });
});

2. UI Interaction Testing

test('should complete form submission', async ({ page }) => {
  await page.goto('/register');

  // Fill form
  await page.fill('input[name="name"]', 'John Doe');
  await page.fill('input[name="email"]', '[email protected]');

  // Submit
  await page.click('button[type="submit"]');

  // Verify success
  await expect(page.locator('.success-message')).toBeVisible();
  await expect(page).toHaveURL('/dashboard');
});

⚠️ Common Pitfalls

1. Skipping Phase 1 (Requirements)

Problem: Unclear requirements → Rework later Solution: Always clarify edge cases upfront

2. Using any for convenience

Problem: Type safety lost → Runtime errors Solution: Invest time in proper types (saves debugging time)

3. No E2E tests

Problem: Manual testing unreliable → Bugs in production Solution: Write tests DURING implementation (not after)

4. Skipping code review

Problem: Performance/security issues missed Solution: ALWAYS run Phase 4 checklist

5. Direct commit to main

Problem: No review, risky deployment Solution: Use feature branches (Rule 20)

🎯 Example: Complete API Development Flow

Scenario: Create "Add to Favorites" API

Phase 1: Requirements

User Story: As a user, I want to save jobs to favorites so I can review them later

Edge Cases:
- What if job already favorited? → Return 200 (idempotent)
- What if job doesn't exist? → Return 404
- What if user not authenticated? → Return 401

Success Criteria:
- API responds < 200ms
- Works on mobile + desktop
- Persists across sessions

Phase 2: Design

// Schema (Zod)
const addFavoriteSchema = z.object({
  jobId: z.string().uuid(),
  userId: z.string().uuid(),
});

// Types
interface Favorite {
  id: string;
  userId: string;
  jobId: string;
  createdAt: Date;
}

// API Interface
POST /api/favorites
Request: { jobId: string }
Response: { favorite: Favorite }
Errors: 401, 404, 500

Phase 3: Implementation

// app/api/favorites/route.ts
export async function POST(request: Request) {
  const session = await getServerSession();
  if (!session) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });

  const body = await request.json();
  const { jobId } = addFavoriteSchema.parse(body);

  const favorite = await prisma.favorite.upsert({
    where: { userId_jobId: { userId: session.user.id, jobId } },
    create: { userId: session.user.id, jobId },
    update: {},
  });

  return NextResponse.json({ favorite }, { status: 200 });
}

Phase 4: Validation

# E2E tests
npx playwright test -g "Favorites API"
✓ should add favorite (201)
✓ should return existing favorite (200 idempotent)
✓ should reject unauthenticated (401)
✓ should reject invalid jobId (400)

# Type check
npm run type-check
✓ 0 errors

# Lint
npm run lint
✓ 0 errors, 0 warnings

Phase 5: Deployment

# Build
npm run build
✓ Build succeeded

# Commit
git add app/api/favorites/
git commit -m "feat: Add favorites API with idempotent upsert"

Last Updated: 2025-11-16 Version: 1.0 Maintainer: WHRESUME Team