File Organization

---
name: file-organization
description: Organize project files and folders for maintainability and scalability. Use when structuring new projects, refactoring folder structure, or establishing conventions. Handles project structure, naming conventions, and file organization best practices.
allowed-tools: Read Write Glob Bash
metadata:
  tags: file-organization, project-structure, folder-structure, naming-conventions
  platforms: Claude, ChatGPT, Gemini
---


# 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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