npx claudepluginhub yonatangross/orchestkit --plugin orkThis skill is limited to using the following tools:
Model complex business domains with entities, value objects, and bounded contexts.
checklists/ddd-checklist.mdreferences/bounded-contexts.mdreferences/domain-events.mdreferences/entities-value-objects.mdreferences/repositories.mdrules/_sections.mdrules/_template.mdrules/aggregate-boundaries.mdrules/aggregate-invariants.mdrules/aggregate-sizing.mdscripts/entity-template.pyscripts/repository-template.pyscripts/value-object-template.pytest-cases.jsonApplies Domain-Driven Design to model software around business domains using bounded contexts, aggregates, ubiquitous language, domain events, and context mapping. For domain modeling, monolith splitting, and microservice boundaries.
Applies DDD tactical patterns using entities, value objects, aggregates, repositories, and domain events to enforce explicit invariants in domain code.
Designs, refactors, analyzes, and reviews code using tactical DDD: aggregates, value objects, repositories, bounded contexts, domain events, avoiding anemic models.
Share bugs, ideas, or general feedback.
Model complex business domains with entities, value objects, and bounded contexts.
┌─────────────────────────────────────────────────────────────┐
│ DDD Building Blocks │
├─────────────────────────────────────────────────────────────┤
│ ENTITIES VALUE OBJECTS AGGREGATES │
│ Order (has ID) Money (no ID) [Order]→Items │
│ │
│ DOMAIN SERVICES REPOSITORIES DOMAIN EVENTS │
│ PricingService IOrderRepository OrderSubmitted │
│ │
│ FACTORIES SPECIFICATIONS MODULES │
│ OrderFactory OverdueOrderSpec orders/, payments/ │
└─────────────────────────────────────────────────────────────┘
from dataclasses import dataclass, field
from uuid import UUID
from uuid_utils import uuid7
@dataclass
class Order:
"""Entity: Has identity, mutable state, lifecycle."""
id: UUID = field(default_factory=uuid7)
customer_id: UUID = field(default=None)
status: str = "draft"
def __eq__(self, other: object) -> bool:
if not isinstance(other, Order):
return NotImplemented
return self.id == other.id # Identity equality
def __hash__(self) -> int:
return hash(self.id)
Load Read("${CLAUDE_SKILL_DIR}/references/entities-value-objects.md") for complete patterns.
from dataclasses import dataclass
from decimal import Decimal
@dataclass(frozen=True) # MUST be frozen!
class Money:
"""Value Object: Defined by attributes, not identity."""
amount: Decimal
currency: str
def __add__(self, other: "Money") -> "Money":
if self.currency != other.currency:
raise ValueError("Cannot add different currencies")
return Money(self.amount + other.amount, self.currency)
Load Read("${CLAUDE_SKILL_DIR}/references/entities-value-objects.md") for Address, DateRange examples.
| Decision | Recommendation |
|---|---|
| Entity vs VO | Has unique ID + lifecycle? Entity. Otherwise VO |
| Entity equality | By ID, not attributes |
| Value object mutability | Always immutable (frozen=True) |
| Repository scope | One per aggregate root |
| Domain events | Collect in entity, publish after persist |
| Context boundaries | By business capability, not technical |
| Rule | Impact | What It Covers |
|---|---|---|
aggregate-boundaries (load ${CLAUDE_SKILL_DIR}/rules/aggregate-boundaries.md) | HIGH | Aggregate root design, reference by ID, one-per-transaction |
aggregate-invariants (load ${CLAUDE_SKILL_DIR}/rules/aggregate-invariants.md) | HIGH | Business rule enforcement, specification pattern |
aggregate-sizing (load ${CLAUDE_SKILL_DIR}/rules/aggregate-sizing.md) | HIGH | Right-sizing, when to split, eventual consistency |
Under 5 entities? Skip DDD entirely. The ceremony costs more than the benefit.
| Pattern | Interview | Hackathon | MVP | Growth | Enterprise | Simpler Alternative |
|---|---|---|---|---|---|---|
| Aggregates | OVERKILL | OVERKILL | OVERKILL | SELECTIVE | APPROPRIATE | Plain dataclasses with validation |
| Bounded contexts | OVERKILL | OVERKILL | OVERKILL | BORDERLINE | APPROPRIATE | Python packages with clear imports |
| CQRS | OVERKILL | OVERKILL | OVERKILL | OVERKILL | WHEN JUSTIFIED | Single model for read/write |
| Value objects | OVERKILL | OVERKILL | BORDERLINE | APPROPRIATE | REQUIRED | Typed fields on the entity |
| Domain events | OVERKILL | OVERKILL | OVERKILL | SELECTIVE | APPROPRIATE | Direct method calls between services |
| Repository pattern | OVERKILL | OVERKILL | BORDERLINE | APPROPRIATE | REQUIRED | Direct ORM queries in service layer |
Rule of thumb: DDD adds ~40% code overhead. Only worth it when domain complexity genuinely demands it (5+ entities with invariants spanning multiple objects). A CRUD app with DDD is a red flag.
# NEVER have anemic domain models (data-only classes)
@dataclass
class Order:
id: UUID
items: list # WRONG - no behavior!
# NEVER leak infrastructure into domain
class Order:
def save(self, session: Session): # WRONG - knows about DB!
# NEVER use mutable value objects
@dataclass # WRONG - missing frozen=True
class Money:
amount: Decimal
# NEVER have repositories return ORM models
async def get(self, id: UUID) -> OrderModel: # WRONG - return domain!
aggregate-patterns - Deep dive on aggregate designork:distributed-systems - Cross-aggregate coordinationork:database-patterns - Schema design for DDDLoad on demand with Read("${CLAUDE_SKILL_DIR}/references/<file>"):
| File | Content |
|---|---|
entities-value-objects.md | Full entity and value object patterns |
repositories.md | Repository pattern implementation |
domain-events.md | Event collection and publishing |
bounded-contexts.md | Context mapping and ACL |
Keywords: entity, identity, lifecycle, mutable, domain object Solves: Model entities in Python, identity equality, adding behavior
Keywords: value object, immutable, frozen, dataclass, structural equality Solves: Create immutable value objects, when to use VO vs entity
Keywords: domain service, business logic, cross-aggregate, stateless Solves: When to use domain service, logic spanning aggregates
Keywords: repository, persistence, collection, IRepository, protocol Solves: Implement repository pattern, abstract DB access, ORM mapping
Keywords: bounded context, context map, ACL, subdomain, ubiquitous language Solves: Define bounded contexts, integrate with ACL, context relationships