Status: IN
Singleton recurs as instance governance infrastructure across all three GoF pattern categories: State subclasses are often Singletons (Behavioral), Facade is typically a Singleton (Structural), and ChangeManager combines Mediator with Singleton (cross-cutting coordination) — validating Singleton as a category-transcendent infrastructure concern rather than merely a Creational mechanism.
Singleton serves as pervasive instance governance across all three GoF categories
Depends on (SL): gof-state-subclasses-often-singletons, facade-often-singleton, gof-changemanager-mediator-singleton