Bikach Domain-Driven Design
Reference for applying Domain-Driven Design, split into strategic design (high-level domain decomposition) and tactical design (building blocks inside a bounded context).
This skill uses progressive disclosure: read the relevant pattern file on demand instead of loading everything at once.
When to Use This Skill
- Modeling a new domain or refactoring an existing one
- Deciding where boundaries belong (bounded contexts, subdomains)
- Choosing the right tactical building block (entity vs value object vs aggregate)
- Establishing a shared vocabulary with the business (ubiquitous language)
- Designing repositories, domain events, factories, or domain services
Do NOT use for infrastructure/DevOps tasks, pure UI work, or anemic CRUD with no business invariants.
Workflow
- Start strategic. Clarify the domain, subdomains, and bounded contexts before writing any code. Establish the ubiquitous language first.
- Map relationships between contexts (partnership, conformist, anti-corruption layer, ...).
- Then go tactical inside a single bounded context: model aggregates, entities, value objects, and the rules that protect invariants.
- Keep the language consistent between code and the strategic model at all times.
Strategic Design
High-level decomposition of the problem space.
| Pattern | File | Use for |
|---|---|---|
| Ubiquitous Language | strategic/ubiquitous-language.md | Shared vocabulary between business and code |
| Subdomain Classification | strategic/subdomain-classification.md | Core / supporting / generic subdomains |
| Bounded Context | strategic/bounded-context.md | Defining explicit model boundaries |
| Context Mapping | strategic/context-mapping.md | Relationships & integration between contexts |
Tactical Design
Building blocks inside a bounded context.
| Pattern | File | Use for |
|---|---|---|
| Entity | tactical/entity.md | Objects with identity and lifecycle |
| Value Object | tactical/value-object.md | Immutable, identity-less concepts |
| Aggregate | tactical/aggregate.md | Consistency boundaries & invariants |
| Domain Event | tactical/domain-event.md | Something meaningful that happened |
| Repository | tactical/repository.md | Persistence abstraction for aggregates |
| Factory | tactical/factory.md | Complex object/aggregate creation |
| Domain Service | tactical/domain-service.md | Stateless domain logic spanning entities |
| Specification | tactical/specification.md | Reusable business rule / query predicate |
Related Skills
- [[architecting-backend]] — hexagonal architecture, SOLID, where DDD building blocks fit
- [[security-guardian]] — validating invariants and inputs at domain boundaries