Foundations

What is Open-Closed Principle?

Design modules so you can add behavior without editing existing code. Extend through new types, not surgery on old ones.

Learn this term every day on iPhone.

One hand-written term. A real workplace example. Thirty seconds before your day gets loud.

In real work

Open-closed principle: we registered a new export handler instead of editing the core pipeline.

How is this different from Googling it?

Google gives a definition. Prompthaus pairs each term with how it shows up in standups, PRs, prompts, and design reviews—then quizzes you until the word sticks. One term a day on iPhone.