m09-domain

m09-domain is a skill for Claude Code from moeru-ai/auv. It costs 55 tokens per session (999 once invoked), scanned A, original, Apache-2.0.

A guide to domain modeling, the practice of representing a business problem in code. It explains concepts such as entities, value objects, aggregates, repositories, domain events, services, and business rules in Rust.

In plain words
What is it for?
Use it when designing business models, deciding whether data needs identity, defining validation rules, setting ownership boundaries, or choosing repository and event patterns.
Why use it?
It helps choose suitable Rust types and ownership patterns so that business rules and valid states are enforced in the code.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it when designing business models, deciding whether data needs identity, defining validation rules, setting ownership boundaries, or choosing repository and event patterns.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/moeru-ai/auv/m09-domain
View source ↗ moeru-ai/auv
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add moeru-ai/auv --skill m09-domain
Clone the repo
git clone --depth 1 https://github.com/moeru-ai/auv

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for m09-domain

README.md
[![agentmods](https://agentmods.dev/badge/skills/moeru-ai/auv/m09-domain/github.svg)](https://agentmods.dev/skills/moeru-ai/auv/m09-domain)
Your own site
<a href="https://agentmods.dev/skills/moeru-ai/auv/m09-domain"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/m09-domain/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for m09-domain

Your own site · 80×15
<a href="https://agentmods.dev/skills/moeru-ai/auv/m09-domain"><img src="https://agentmods.dev/badge/skills/moeru-ai/auv/m09-domain.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 999 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00055 $0.00999
Opus 5 $0.00028 $0.00500
Sonnet 5 $0.00011 $0.00200
Haiku 4.5 $0.00006 $0.00100

Measured 10d ago against content hash a05f32b475b0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

m09-domain scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/m09-domain/SKILL.md · 175 lines

How it starts

The opening of the file, as written. The whole thing — 175 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Domain Modeling

Layer 2: Design Choices

Core Question

What is this concept's role in the domain?

Before modeling in code, understand:

  • Is it an Entity (identity matters) or Value Object (interchangeable)?
  • What invariants must be maintained?
  • Where are the aggregate boundaries?

Domain Concept → Rust Pattern

Domain Concept Rust Pattern Ownership Implication
Entity struct + Id Owned, unique identity
Value Object struct + Clone/Copy Shareable, immutable
Aggregate Root struct owns children Clear ownership tree
Repository trait Abstracts persistence
Domain Event enum Captures state changes
Service impl block / free fn Stateless operations

Thinking Prompt

Before creating a domain type:

  1. What's the concept's identity?

    • Needs unique identity → Entity (Id field)
    • Interchangeable by value → Value Object (Clone/Copy)
  2. What invariants must hold?

    • Always valid → private fields + validated constructor
    • Transition rules → type state pattern
  3. Who owns this data?

    • Single owner (parent) → owned field
    • Shared reference → Arc/Rc
    • Weak reference → Weak

Trace Up ↑

To domain constraints (Layer 3):

"How should I model a Transaction?"
    ↑ Ask: What domain rules govern transactions?
    ↑ Check: domain-fintech (audit, precision requirements)
    ↑ Check: Business stakeholders (what invariants?)
Design Question Trace To Ask
Entity vs Value Object domain-* What makes two instances "the same"?
Aggregate boundaries domain-* What must be consistent together?
Validation rules domain-* What business rules apply?

Trace Down ↓

To implementation (Layer 1):

"Model as Entity"
    ↓ m01-ownership: Owned, unique
    ↓ m05-type-driven: Newtype for Id

"Model as Value Object"
    ↓ m01-ownership: Clone/Copy OK
    ↓ m05-type-driven: Validate at construction

"Model as Aggregate"
    ↓ m01-ownership: Parent owns children
    ↓ m02-resource: Consider Rc for shared within aggregate

Read the full file on GitHub · 175 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 175 lines · 55 tokens per session scan A a05f32b475b0

Subscribe to this mod's changes

m09-domain is a skill published in the GitHub repository moeru-ai/auv (27 stars, last pushed 2d ago), licensed Apache-2.0. It adds 55 tokens to every session and 999 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

add-backend

Guide for adding a backend (Rust or Python) to the agent-sec-core security middleware. Use when creating new backends, integrating Rust or Python code into the security middleware, or extending with new backend actions.

alibaba/anolisa · 46 tokens

claude-api

Build, debug, and optimize Claude API / Anthropic SDK apps. Apps built with this skill should include prompt caching. Also handles migrating existing Claude API code between Claude model versions (4.5 → 4.6, 4.6 → 4.7, retired-model replacements). TRIGGER when: code imports anthropic/@anthropic-ai/sdk; user asks for…

Prismer-AI/PrismerCloud · 193 tokens

telegram

Owner-only Telegram text bridge and Mini App gateway for the existing Ouroboros interface.

razzant/ouroboros · 19 tokens

verify

Build, launch, and drive a local Honcho stack to verify a change at its runtime surface (the /v3 HTTP API and the deriver queue). Use when verifying a diff or confirming a change works in the running app.

plastic-labs/honcho · 49 tokens

remindb-setup

Config-first setup wizard for a remindb MCP server — run it as /remindb-setup (interactive), /remindb-setup automode (hands-off), or /remindb-setup only-config (bridge hosts: author .remindb/ only, no env wiring). Two passes. First-time (no server attached yet): detect the host, author the .remindb/ config…

radimsem/remindb · 202 tokens

binder-app

Build a small HTTP app (dashboard, kanban board, admin panel, custom UI) on top of an existing Binder workspace. Use when asked to "create an app", "build a dashboard", "show records in a chart", "make a kanban/board", "build an admin panel", or "add a UI on top of binder".

mpazik/Binder · 74 tokens