Summary

Pattern Comparison

Pattern	When to Apply	Strengths	Caveats	Common Use Cases
Singleton	When a shared instance is required	Centralized state, easy access	Can complicate testing and mocking	Logger, configuration, caching
Facade	When simplifying multiple internal calls	Clean API surface, hides internal logic	Facade may grow too complex internally	Subsystem access, logging wrapper

Choosing the Right Pattern

• For unified access to shared utilities → Singleton
• To simplify multiple operations into one call → Facade
• Consider combining with Dependency Injection (DI) or Adapter to improve testability and flexibility

Team Discussion Snippets

• “We’re calling Logger directly everywhere—let’s make it a Singleton.”
• “Logging and config access could be wrapped in a Facade for cleaner usage.”
• “If we’re using process.env all over, let’s centralize it with a Config class.”