Modularity
also: modular, modularize, modularized
Building an app out of separate, self-contained parts, each covering one area, that can be understood and changed on their own.
The degree to which a system is divided into modules with clear boundaries and small public interfaces. Good modularity lets you understand, test, replace or delete one part without reading or breaking the rest. It's how one codebase stays manageable as it grows.
A bookshelf built from separate cubes. You can swap one cube, move it, or add another without rebuilding the whole shelf.
A modular codebase is easier for agents too: they can work in one area with less risk of breaking others. Asking for modular changes keeps an agent's work contained and easier to review.
To keep this modular, the loyalty points logic lives in src/loyalty with one public function, awardPoints(). Nothing else imports its internal files.
Put the new invoicing feature in its own module with a small public interface. Other parts of the app should only call those functions.
Thinking modularity means splitting into separate services or apps. A single codebase can be highly modular, and a set of microservices can still be tangled.