// design pattern katas

Pick a problem.

Refactor real-world code into clean, extensible designs. Each kata drops you into an editor with a failing starter and an AI reviewer.

6 problemsAll

Replace a giant switch statement with the Strategy Pattern so new payment methods drop in cleanly.

Let subscribers react to events without the publisher knowing about them, using the Observer Pattern.

Centralize object creation behind a Factory so callers stop newing up concrete classes everywhere.

Guarantee a single shared instance of app config with a well-behaved Singleton.

Make an incompatible third-party client fit your interface with the Adapter Pattern.

Add behavior to objects at runtime by stacking Decorators instead of subclassing.