Flyweight Pattern Best Practices in C#: Code Organization and Maintainability

A comprehensive guide to implementing the flyweight pattern correctly in C#. Covers making intrinsic state immutable using records and readonly fields, building thread-safe factories with ConcurrentDictionary and Lazy<T>, cleanly separating intrinsic from extrinsic state, monitoring memory and implementing cache eviction with WeakReference, testing identity sharing with Assert.Same and concurrency tests, naming conventions, DI container integration as singletons, and combining flyweight with composite, strategy, and observer patterns. Also addresses common pitfalls like mutable shared state, unbounded caches, and serialization edge cases.