Python Design Patterns skill: what it does and how to install it

What it does. Applies KISS, single responsibility, separation of concerns, composition over inheritance and the rule of three when designing or refactoring Python code. It helps split tangled components, keep functions focused, inject dependencies, choose abstractions and preserve API-to-service-to-repository layering.

When to use it. For new services, complex refactors, structural code reviews, abstraction decisions, inheritance choices and codebases where I/O and business logic are difficult to test. It also covers diagnosing oversized classes and dependency-direction violations.