SOLID Principles for Node.js/TypeScript Overview SOLID principles adapted for functional and TypeScript-first development. S - Single Responsibility Principle A module/function should have only one reason to change. Violation Correct O - Open/Closed Principle Open for extension, closed for modification. Violation Correct L - Liskov Substitution Principle Subtypes must be substitutable for their base types. Violation Correct I - Interface Segregation Principle Clients should not depend on interfaces they don't use. Violation Correct D - Dependency Inversion Principle Depend on abstractions, no…