One question decides where code lives

In a large modular monolith the biggest question is where each file goes. In SimaCMS the answer is one question: “could a site be without it?” If yes, it is a module, with its own frontend, migrations and tests. If no, it is part of the chassis: authentication, payments, the wallet, notifications and media.

A boundary that is held

A module never names another module. If two modules need something, it is a contract the core declares and the modules contribute to. A guard checks this on every PR.

Why it is worth it

A site that bought one module must boot without the others. A module that depends on another breaks that.