Domain Driven Design

What it does

When your agent uses it

• Building rich domain models
• Enforcing invariants
• Separating domain logic from infrastructure

Example prompts

• “/domain-driven-design”

Requirements

• Python 3
• Compatibility (from SKILL.md): Claude Code 2.1.277+.
• Pre-approved tools (allowed-tools): Read, Glob, Grep, WebFetch, WebSearch

What it can do on your machine

Read from SKILL.md and the folder at commit 02bbf9a. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Glob
  • Grep
  • WebFetch
  • WebSearch

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Ships 3 files in scripts/ (Python), which the agent can run.

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • learn.microsoft.com
  • docs.python.org
  • postgresql.org
  • github.com
  • docs.stripe.com
  • redis.io

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Claude Code 2.1.277+.

  From compatibility in the SKILL.md frontmatter.

Context cost

Domain Driven Design loads about 2.3k tokens when it runs, and up to ~6.1k if it reads all its reference files. Until then it costs about 90 tokens; SKILL.md has 613 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~90

When it runs · the whole SKILL.md, loaded when a task matches

~2.3k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~6.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from yonatangross/orchestkit at commit 02bbf9a, republished under its MIT licence (© yonatangross). 613 words, ~2,298 tokens.

name

domain-driven-design

description

DDD tactical patterns for complex business modeling including entities, value objects, aggregates, domain services, repositories, specifications, and bounded contexts. Python dataclass implementations with TypeScript alternatives. Use when building rich domain models, enforcing invariants, or separating domain logic from infrastructure.

allowed-tools

Read, Glob, Grep, WebFetch, WebSearch

compatibility

Claude Code 2.1.277+.

license

MIT

user-invocable

false

disable-model-invocation

true

metadata.owner-agent

backend-system-architect

metadata.category

document-asset-creation

metadata.version

1.0.0

metadata.author

OrchestKit

metadata.complexity

medium

metadata.tags

ddd, domain-modeling, entities, value-objects, bounded-contexts, python

┌─────────────────────────────────────────────────────────────┐
│                    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)

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)

# 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!

© yonatangross, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 11 other files (scripts, references) in src/skills/domain-driven-design of yonatangross/orchestkit.

• SKILL.md
• references/ork-delta.md
• references/repositories.md
• rules/_sections.md
• rules/_template.md
• rules/aggregate-boundaries.md
• rules/aggregate-invariants.md
• rules/aggregate-sizing.md
• scripts/entity-template.py
• scripts/repository-template.py
• scripts/value-object-template.py
• test-cases.json

Open the folder on GitHubat commit 02bbf9a