Architecture Boundaries (Clean Architecture)

Operates at SYSTEM level (layers, boundaries, components). For MODULE level (interface depth, information hiding), use aposd-designing-deep-modules.

SRP Is About Actors, Not "Doing One Thing"

"A module should be responsible to one, and only one, actor."

An actor is a group of users/stakeholders who request changes. If two actors share a class, a change for one can break the other.

// BEFORE: One class serves three actors
class Employee {
    Money calculatePay() { }      // CFO's accounting team
    String reportHours() { }      // COO's HR team
    void save() { }               // CTO's DBA team
}