file-organization

# Project File Organization


## When to use this skill

- **New Projects**: Initial folder structure design
- **Project Growth**: Refactoring when complexity increases
- **Team Standardization**: Establish consistent structure

## Instructions

### Step 1: React/Next.js Project Structure

```
src/
├── app/                      # Next.js 13+ App Router
│   ├── (auth)/               # Route groups
│   │   ├── login/
│   │   └── signup/
│   ├── (dashboard)/
│   │   ├── layout.tsx
│   │   ├── page.tsx
│   │   └── settings/
│   ├── api/                  # API routes
│   │   ├── auth/
│   │   └── users/
│   └── layout.tsx
│
├── components/               # UI Components
│   ├── ui/                   # Reusable UI (Button, Input)
│   │   ├── Button/
│   │   │   ├── Button.tsx
│   │   │   ├── Button.test.tsx
│   │   │   └── index.ts
│   │   └── Input/
│   ├── layout/               # Layout components (Header, Footer)
│   ├── features/             # Feature-specific components
│   │   ├── auth/
│   │   └── dashboard/
│   └── shared/               # Shared across features
│
├── lib/                      # Utilities & helpers
│   ├── utils.ts
│   ├── hooks/
│   │   ├── useAuth.ts
│   │   └── useLocalStorage.ts
│   └── api/
│       └── client.ts
│
├── store/                    # State management
│   ├── slices/
│   │   ├── authSlice.ts
│   │   └── userSlice.ts
│   └── index.ts
│
├── types/                    # TypeScript types
│   ├── api.ts
│   ├── models.ts
│   └── index.ts
│
├── config/                   # Configuration
│   ├── env.ts
│   └── constants.ts
│
└── styles/                   # Global styles
    ├── globals.css
    └── theme.ts
```

### Step 2: Node.js/Express Backend Structure

```
src/
├── api/                      # API layer
│   ├── routes/
│   │   ├── auth.routes.ts
│   │   ├── user.routes.ts
│   │   └── index.ts
│   ├── controllers/
│   │   ├── auth.controller.ts
│   │   └── user.controller.ts
│   └── middlewares/
│       ├── auth.middleware.ts
│       ├── errorHandler.ts
│       └── validation.ts
│
├── services/                 # Business logic
│   ├── auth.service.ts
│   ├── user.service.ts
│   └── email.service.ts
│
├── repositories/             # Data access layer
│   ├── user.repository.ts
│   └── session.repository.ts
│
├── models/                   # Database models
│   ├── User.ts
│   └── Session.ts
│
├── database/                 # Database setup
│   ├── connection.ts
│   ├── migrations/
│   └── seeds/
│
├── utils/                    # Utilities
│   ├── logger.ts
│   ├── crypto.ts
│   └── validators.ts
│
├── config/                   # Configuration
│   ├── index.ts
│   ├── database.ts
│   └── env.ts
│
├── types/                    # TypeScript types
│   ├── express.d.ts
│   └── models.ts
│
├── __tests__/                # Tests
│   ├── unit/
│   ├── integration/
│   └── e2e/
│
└── index.ts                  # Entry point
```

### Step 3: Feature-Based Structure (Large-Scale Apps)

```
src/
├── features/
│   ├── auth/
│   │   ├── components/
│   │   │   ├── LoginForm.tsx
│   │   │   └── SignupForm.tsx
│   │   ├── hooks/
│   │   │   └── useAuth.ts
│   │   ├── api/
│   │   │   └── authApi.ts
│   │   ├── store/
│   │   │   └── authSlice.ts
│   │   ├── types/
│   │   │   └── auth.types.ts
│   │   └── index.ts
│   │
│   ├── products/
│   │   ├── components/
│   │   ├── hooks/
│   │   ├── api/
│   │   └── types/
│   │
│   └── orders/
│
├── shared/                   # Shared across features
│   ├── components/
│   ├── hooks/
│   ├── utils/
│   └── types/
│
└── core/                     # App-wide
    ├── store/
    ├── router/
    └── config/
```

### Step 4: Naming Conventions

**File Names**:
```
Components:       PascalCase.tsx
Hooks:            camelCase.ts        (useAuth.ts)
Utils:            camelCase.ts        (formatDate.ts)
Constants:        UPPER_SNAKE_CASE.ts (API_ENDPOINTS.ts)
Types:            camelCase.types.ts  (user.types.ts)
Tests:            *.test.ts, *.spec.ts
```

**Folder Names**:
```
kebab-case:       user-profile/
camelCase:        userProfile/       (optional: hooks/, utils/)
PascalCase:       UserProfile/       (optional: components/)

✅ Consistency is key (entire team uses the same rules)
```

**Variable/Function Names**:
```typescript
// Components: PascalCase
const UserProfile = () => {};

// Functions: camelCase
function getUserById() {}

// Constants: UPPER_SNAKE_CASE
const API_BASE_URL = 'https://api.example.com';

// Private: _prefix (optional)
class User {
  private _id: string;

  private _hashPassword() {}
}

// Booleans: is/has/can prefix
const isAuthenticated = true;
const hasPermission = false;
const canEdit = true;
```

### Step 5: index.ts Barrel Files

**components/ui/index.ts**:
```typescript
// ✅ Good example: Re-export named exports
export { Button } from './Button/Button';
export { Input } from './Input/Input';
export { Modal } from './Modal/Modal';

// Usage:
import { Button, Input } from '@/components/ui';
```

**❌ Bad example**:
```typescript
// Re-export everything (impairs tree-shaking)
export * from './Button';
export * from './Input';
```

## Output format

### Project Template

```
my-app/
├── .github/
│   └── workflows/
├── public/
├── src/
│   ├── app/
│   ├── components/
│   ├── lib/
│   ├── types/
│   └── config/
├── tests/
├── docs/
├── scripts/
├── .env.example
├── .gitignore
├── .eslintrc.json
├── .prettierrc
├── tsconfig.json
├── package.json
└── README.md
```

## Constraints

### Required Rules (MUST)

1. **Consistency**: Entire team uses the same rules
2. **Clear Folder Names**: Roles must be explicit
3. **Max Depth**: Recommend 5 levels or fewer

### Prohibited (MUST NOT)

1. **Excessive Nesting**: Avoid 7+ levels of folder depth
2. **Vague Names**: Avoid utils2/, helpers/, misc/
3. **Circular Dependencies**: Prohibit A → B → A references

## Best practices

1. **Colocation**: Keep related files close (component + styles + tests)
2. **Feature-Based**: Modularize by feature
3. **Path Aliases**: Simplify imports with `@/`

**tsconfig.json**:
```json
{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "@/*": ["./src/*"],
      "@/components/*": ["./src/components/*"],
      "@/lib/*": ["./src/lib/*"]
    }
  }
}
```

**Usage**:
```typescript
// ❌ Bad example
import { Button } from '../../../components/ui/Button';

// ✅ Good example
import { Button } from '@/components/ui';
```

## References

- [React File Structure](https://react.dev/learn/thinking-in-react#step-1-break-the-ui-into-a-component-hierarchy)
- [Node.js Best Practices](https://github.com/goldbergyoni/nodebestpractices)
- [Clean Architecture](https://blog.cleancoder.com/uncle-bob/2012/08/13/the-clean-architecture.html)

## Metadata

### Version
- **Current Version**: 1.0.0
- **Last Updated**: 2025-01-01
- **Compatible Platforms**: Claude, ChatGPT, Gemini

### Tags
`#file-organization` `#project-structure` `#folder-structure` `#naming-conventions` `#utilities`

## Examples

### Example 1: Basic usage
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### Example 2: Advanced usage
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