Domain-Driven Design (DDD) Core Principles 1. Aggregates define consistency boundaries — An aggregate is a cluster of entities and value objects treated as a single unit for data changes. All invariants within an aggregate are enforced in a single transaction. Cross-aggregate consistency is eventual. 2. Value objects over primitives — Replace primitive obsession with value objects. , , are not strings — they carry validation, equality, and behavior. Use C# records for immutable value objects. 3. Domain events decouple side effects — When something meaningful happens in the domain (OrderPlaced…