SOLID Principles Apply SOLID design principles for maintainable, flexible code architecture. The Five Principles 1. Single Responsibility Principle (SRP) A module should have one, and only one, reason to change Elixir Pattern TypeScript Pattern Ask yourself: "What is the ONE thing this module does?" 2. Open/Closed Principle (OCP) Software entities should be open for extension, closed for modification. Elixir Pattern (Behaviours) TypeScript Pattern (Composition) Ask yourself: "Can I add new functionality without changing existing code?" 3. Liskov Substitution Principle (LSP) Subtypes must be s…