rule

English-Only Development Rule

This rule enforces that all code, comments, and documentation must be written in English throughout the project.

Scope

This rule applies to:

• All source code files (.ts, .js, .tsx, .jsx, etc.)
• All comments within code files
• All documentation files (.md, .mdx, etc.)
• All configuration files with text content
• All README files and project documentation

Requirements

Code Files

• Variable names: Must be in English
• Function names: Must be in English
• Class names: Must be in English
• Comments: Must be in English
• String literals: User-facing strings should be in English (use i18n for localization)
• Error messages: Must be in English

Documentation Files

• README files: Must be in English
• API documentation: Must be in English
• Code comments: Must be in English
• Inline documentation: Must be in English

Configuration Files

• Comments in config files: Must be in English
• Descriptive text: Must be in English

Examples

✅ Correct (English)

// Initialize the user authentication service
const authService = new AuthenticationService();

/**
 * Validates user credentials and returns authentication token
 * @param username - The user's username
 * @param password - The user's password
 * @returns Promise<AuthToken>
 */
async function validateCredentials(username: string, password: string): Promise<AuthToken> {
  // Check if user exists in database
  const user = await findUserByUsername(username);

  if (!user) {
    throw new Error('User not found');
  }

  // Verify password hash
  const isValidPassword = await verifyPassword(password, user.passwordHash);

  if (!isValidPassword) {
    throw new Error('Invalid credentials');
  }

  return generateAuthToken(user);
}

❌ Incorrect (French)

// Initialiser le service d'authentification utilisateur
const serviceAuth = new ServiceAuthentification();

/**
 * Valide les identifiants utilisateur et retourne le token d'authentification
 * @param nomUtilisateur - Le nom d'utilisateur
 * @param motDePasse - Le mot de passe
 * @returns Promise<AuthToken>
 */
async function validerIdentifiants(nomUtilisateur: string, motDePasse: string): Promise<AuthToken> {
  // Vérifier si l'utilisateur existe dans la base de données
  const utilisateur = await trouverUtilisateurParNom(nomUtilisateur);

  if (!utilisateur) {
    throw new Error('Utilisateur non trouvé');
  }

  // Vérifier le hash du mot de passe
  const motDePasseValide = await verifierMotDePasse(motDePasse, utilisateur.hashMotDePasse);

  if (!motDePasseValide) {
    throw new Error('Identifiants invalides');
  }

  return genererTokenAuth(utilisateur);
}