# Coding Standards

## Critical Fullstack Rules

- **API Error Handling:** All API routes must use the centralized error handler middleware. Never send raw errors to clients.

- **Input Validation:** All POST/PUT endpoints must validate inputs using express-validator. Frontend should also validate before sending.

- **Database Access:** Always use Prisma ORM for database operations. Never write raw SQL queries (except for complex queries Prisma can't handle).

- **Environment Variables:** Access environment variables only through centralized config. Never use `process.env` or `import.meta.env` directly in components/controllers.

- **Date Handling:** Use date-fns for all date manipulation. Never use vanilla JavaScript Date methods for calculations.

- **Component Structure:** React components must be functional with hooks. No class components.

- **State Updates:** Never mutate state directly. Use setState/setters or Context dispatch actions.

- **API Calls:** Never make direct fetch calls in components. Always use the service layer (booksService, logsService).

- **Error Boundaries:** Critical routes must have React Error Boundaries to catch and display errors gracefully.

- **Prisma Schema Changes:** Never modify database directly. Always create Prisma migrations for schema changes.

## Naming Conventions

| Element | Frontend | Backend | Example |
|---------|----------|---------|---------|
| **Components** | PascalCase | - | `BookCard.jsx`, `LogProgressModal.jsx` |
| **Hooks** | camelCase with 'use' prefix | - | `useBooks.js`, `useProgress.js` |
| **Services** | camelCase with 'Service' suffix | camelCase with 'Service' suffix | `booksService.js`, `openLibraryService.js` |
| **Controllers** | - | camelCase with 'Controller' suffix | `booksController.js` |
| **API Routes** | - | kebab-case | `/api/books`, `/api/books/:id/logs` |
| **Database Tables** | - | PascalCase (Prisma convention) | `Book`, `ReadingLog` |
| **Files** | kebab-case | kebab-case | `book-card.jsx`, `pace-calculation-service.js` |
| **CSS Classes** | kebab-case (Tailwind) | - | `text-blue-500`, `book-card-container` |
| **Functions** | camelCase | camelCase | `calculateRequiredPace()`, `handleLogClick()` |
| **Constants** | SCREAMING_SNAKE_CASE | SCREAMING_SNAKE_CASE | `API_BASE_URL`, `MAX_QUERY_LENGTH` |

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