clean-codelisted

# Clean Code Skill Write readable, maintainable code following Clean Code principles. ## When to Use - User says "clean this code" / "refactor" / "improve readability" - Code review focusing on maintainability - Reducing complexity - Improving naming --- ## Core Principles | Principle | Meaning | Violation Sign | |-----------|---------|----------------| | **DRY** | Don't Repeat Yourself | Copy-pasted code blocks | | **KISS** | Keep It Simple, Stupid | Over-engineered solutions | | **YAGNI** | You Aren't Gonna Need It | Features "just in case" | --- ## DRY - Don't Repeat Yourself > "Every piece of knowledge must have a single, unambiguous representation in the system." ### Violation ```java // ❌ BAD: Same validation logic repeated public class UserController { public void createUser(UserRequest request) { if (request.getEmail() == null || request.getEmail().isBlank()) { throw new ValidationException("Email is required"); } if (!request.getEmail().contains("@")) { throw new ValidationException("Invalid email format"); } // ... create user } public void updateUser(UserRequest request) { if (request.getEmail() == null || request.getEmail().isBlank()) { throw new ValidationException("Email is required"); } if (!request.getEmail().contains("@")) { throw new ValidationException("Invalid email format"); } // ... update user } } ``