domain-modeling

domain-modeling is a skill for Claude Code, Codex from int2t05/engineering-skills. It costs 69 tokens per session (1,094 once invoked), scanned A, original, MIT.

A guide to defining and testing the important concepts and relationships in a software project's subject area, then recording the agreed vocabulary and decisions.

In plain words
What is it for?
Use it to refine a domain model, settle terminology, test it against scenarios, update CONTEXT.md, and record difficult or important decisions in ADRs.
Why use it?
It prevents teammates and code from using the same words in different ways, especially when edge cases expose unclear concepts.

Skill for Claude CodeCodex

Written for Claude Code and Codex: ${CLAUDE_PLUGIN_ROOT} variable, but also agents/openai.yaml present.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the engineering-skills plugin — 47 skills, 1 hook shipped together

Good fit Use it to refine a domain model, settle terminology, test it against scenarios, update CONTEXT.md, and record difficult or important decisions in ADRs.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add int2t05/engineering-skills
Claude Code
/plugin install engineering-skills

Made for: Claude Code, Codex.

Or install engineering-skills, the plugin that ships this one along with the rest of its 47 skills, 1 hook.

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 domain-modeling

README.md
[![agentmods](https://agentmods.dev/badge/skills/int2t05/engineering-skills/domain-modeling.svg)](https://agentmods.dev/skills/int2t05/engineering-skills/domain-modeling)
Your own site
<a href="https://agentmods.dev/skills/int2t05/engineering-skills/domain-modeling"><img src="https://agentmods.dev/badge/skills/int2t05/engineering-skills/domain-modeling.svg" alt="Measured on agentmods" height="20"></a>
Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,094 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.
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 $0.00069 $0.01094
Opus 5 $0.00034 $0.00547
Sonnet 5 $0.00014 $0.00219
Haiku 4.5 $0.00007 $0.00109

Measured 7d ago against content hash a97b8a1c0da5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

domain-modeling 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 7d 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.

skills/03-design/domain-modeling/SKILL.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Domain Modeling

Actively build and sharpen the project's domain model as you design. This is the active discipline — challenging terms, inventing edge-case scenarios, and writing the glossary and decisions down the moment they crystallise. This skill is for when you're changing the model.

When to use

  • Pinning down domain terminology or establishing a ubiquitous language
  • A term the user uses conflicts with the existing CONTEXT.md glossary
  • Stress-testing domain relationships against concrete edge-case scenarios
  • Recording an architectural decision that is hard to reverse, surprising, or a real trade-off
  • Another skill needs to maintain or update the domain model
  • Triggers on "domain model", "ubiquitous language", "CONTEXT.md", "ADR", "领域模型", "统一语言", "领域建模"

Not for: merely reading CONTEXT.md for vocabulary — that's a habit any skill can do; this skill is for when you're changing the model. NOT for greenfield system architecture (use architecture).

Steps

1. Locate the context

Most repos have a single CONTEXT.md at the root. If a CONTEXT-MAP.md exists, the repo has multiple contexts — read it to find which context the current topic relates to. If neither exists, create a root CONTEXT.md lazily when the first term is resolved. Create docs/design/adr/ lazily when the first ADR is needed.

2. Challenge terms against the glossary

When the user uses a term that conflicts with the existing language in CONTEXT.md, call it out immediately. "Your glossary defines 'cancellation' as X, but you seem to mean Y — which is it?"

When terms are vague or overloaded, propose a precise canonical term. "You're saying 'account' — do you mean the Customer or the User? Those are different things."

3. Stress-test with concrete scenarios

When domain relationships are being discussed, invent scenarios that probe edge cases and force the user to be precise about the boundaries between concepts. The awkward cases — the happy path, a tricky edge case, an attempt at something that should be illegal — are where the model breaks.

Read the full file on GitHub · 90 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 90 lines · 69 tokens per session scan A a97b8a1c0da5

Subscribe to this mod's changes

domain-modeling is a skill published in the GitHub repository int2t05/engineering-skills (3 stars, last pushed 7d ago), licensed MIT. It adds 69 tokens to every session and 1,094 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 2026-08-31.

Related

Other skills, from other repositories

deep-plan

Creates detailed, sectionized, TDD-oriented implementation plans through research, stakeholder interviews, and multi-LLM review. Use when planning features that need thorough pre-implementation analysis.

piercelamb/deep-plan · 39 tokens

goal-test

A local experiment for testing a goal command that keeps an AI coding session working until a stated condition is judged complete. It uses a separate language model to evaluate the conversation after each assistant turn.

restarter/lets-workflow · 137 tokens

test-audit

Audit test suites for T1-T4 violations using AST analysis, mock detection, and multi-stage synthesis. Invoke when user asks to audit tests, check test quality, find mock violations, review test effectiveness, or inspect test suites for over-mocking. Triggers automatic rewrites when quality gates fail.

QBall-Inc/the-bulwark · 0 tokens

mutation-test

Mutation testing with two engines. Uses the project's NATIVE mutation runner (StrykerJS / Infection / mutmut / PIT / cargo-mutants) when one is configured — installing it on explicit consent when it is not — for a reproducible, comparable score; and an LLM-guided engine for the mutation classes native mutators cannot…

greglas75/zuvo · 190 tokens

plan

Analyzes architecture, selects patterns, assesses testability, then decomposes work into ordered TDD tasks with exact verification commands and explicit acceptance mapping. Works from an approved spec (zuvo:brainstorm output) or directly from a user-provided description.

greglas75/zuvo · 53 tokens

clean-code

This skill should be used when the user asks to "refactor code", "review code quality", "apply clean code principles", "check for code smells", "improve code design", "do a clean code review", "apply SOLID principles", "fix naming", "reduce complexity", or when performing the refactor phase of a TDD cycle.

t1/tdder · 75 tokens