Lesson 8: Value objects and records

This lesson practices Value objects and records at real C# application level. We start from design pain, study code, practice a small decision, predict behavior, and verify mastery.

Immutable value objects make invalid states hard to represent.

Value objects and records: Immutable value objects make invalid states hard to represent.
design pressure: A repeated change, duplication, or test pain that signals the model needs a better boundary.