Domain-Driven Design (DDD) structures complex business software around the domain model, making it particularly effective in finance, healthcare, and e-commerce. Java's strong typing and mature ecosystem enable robust DDD implementations. This paper examines how compile-time and runtime annotation processing complement DDD: compile-time processors enforce structure and generate boilerplate, while runtime validation (e.g., Bean Validation) enforces business rules without polluting domain classes. We present patterns, code snippets, and trade-offs for eventless DDD aligned with modular monoliths and microservices.