ddd

Domain-Driven Design (DDD) Skill

Tactical DDD patterns for the domain layer (core/).

When to Use This Skill

• Designing new domain concepts (entities, value objects, aggregates)
• Reviewing domain model for DDD compliance
• Identifying aggregate boundaries
• Extracting value objects from primitives
• Modeling domain events
• Creating repository protocols

DDD Tactical Patterns

1. Entities

Definition: Objects with identity that persists over time.

2. Value Objects

Definition: Immutable objects defined by their attributes, not identity.

3. Aggregates

Definition: Cluster of domain objects treated as a unit for consistency.

4. Ports (Interfaces)

Definition: Abstract protocols defining contracts between layers.

Clean Architecture Mapping

DDD Concept	Location	Example
Entity	core/entities/	User, Document
Value Object	core/value_objects/	Email, CPR
Port	core/interfaces/	UserRepository, LLMGateway
Domain Service	core/domain_services/	PasswordPolicy
Application Service	application/services/	UserService
Repository Impl	infrastructure/persistence/repositories/	SQLAlchemyUserRepository