CLAUDE Framework

Production-ready coding standards for building maintainable, secure, and well-tested software.

Code Quality (C-1 to C-5)

• C-1: Single Responsibility Principle - each function/class does ONE thing
• C-2: DRY (Don't Repeat Yourself) - no code duplication
• C-3: KISS (Keep It Simple) - simplicity over complexity
• C-4: Functions maximum 20 lines (split if longer)
• C-5: Prefer composition over inheritance

Naming Conventions (N-1 to N-6)

• N-1: Use descriptive names that explain intent
• N-2: Functions = verbs: calculateTotal(), validateUserInput()
• N-3: Variables = nouns: userAccount, totalPrice
• N-4: Booleans start with is/has/can/should: isValid, hasPermission
• N-5: Constants in UPPER_SNAKE_CASE: MAX_RETRY_ATTEMPTS
• N-6: Avoid abbreviations: use user not usr

Error Handling (E-1 to E-5)

• E-1: Handle ALL possible error scenarios
• E-2: Use specific error types/messages
• E-3: Log errors with context information
• E-4: NEVER allow silent failures
• E-5: Fail fast - validate inputs early

Security (SEC-1 to SEC-5)

• SEC-1: Validate ALL inputs at system boundaries
• SEC-2: Sanitize output data
• SEC-3: Use environment variables for secrets
• SEC-4: Never hardcode sensitive information
• SEC-5: Implement proper authentication and authorization

Testing Standards (T-1 to T-5)

• T-1: Write failing test first, then implement (TDD)
• T-2: Minimum 80% code coverage for new code
• T-3: Test happy path, error scenarios, and edge cases
• T-4: Descriptive test names explaining what is tested
• T-5: Arrange-Act-Assert pattern clearly separated

Test Quality (TQ-1 to TQ-5)

• TQ-1: Use realistic test data, no magic numbers
• TQ-2: One assertion per test where possible
• TQ-3: Ensure test isolation
• TQ-4: Tests must be deterministic (no flaky tests)
• TQ-5: Tests should run fast (mock external dependencies)

Database (DB-1 to DB-4)

• DB-1: Use transactions for multi-step operations
• DB-2: Optimize queries (avoid N+1 problems)
• DB-3: Document indexing strategy
• DB-4: Create migration and rollback scripts

Logging (L-1 to L-4)

• L-1: Structured logging (JSON format)
• L-2: NEVER log sensitive data
• L-3: Include correlation IDs for tracing
• L-4: Use appropriate log levels: DEBUG, INFO, WARN, ERROR

Code Structure Requirements

• Organize imports clearly (stdlib, third-party, local)
• Define constants at module level
• Use pure functions where possible
• Implement proper error boundaries
• Include comprehensive JSDoc/comments for complex logic
• Follow consistent indentation (2 or 4 spaces)
• Maximum 120 characters per line

Quality Assurance Checklist

Before delivering code, verify:

• ✅ Functions under 20 lines
• ✅ Single responsibility maintained
• ✅ No code duplication
• ✅ Clear naming conventions followed
• ✅ All errors handled with specific types
• ✅ Input validation implemented
• ✅ Output sanitization applied
• ✅ Tests written and passing (80%+ coverage)
• ✅ Security considerations addressed
• ✅ Performance implications considered
• ✅ Documentation updated