Skills mattpocock skills Engineering workflow
domain-modeling
- Use it when:
- You're pinning down what your project's business terms mean, editing its GLOSSARY.md, or recording a design decision.
- It does:
- Challenges vague or conflicting terms, tests them with edge cases and checks them against the code.
- You get:
- An up-to-date GLOSSARY.md and, for the big decisions only, ADRs (short decision records) in docs/adr/.
- Unlike grill-with-docs:
- It runs no interview of its own; it steps in whenever terms come up, and grill-with-docs runs it alongside its questions.
- Runs:
- By itself when terminology, the glossary or a decision record comes up.
Skill 6 of 24 in the Engineering workflow bundle, after grilling and before research.
TL;DR
It keeps the project's vocabulary straight: the words people and code use for the things the software deals with, like orders, customers or cancellations. It's for changing that vocabulary, not just looking it up. When you use a word differently from GLOSSARY.md, the agent says so at once; when a word is vague ("account": the customer or the user?), it proposes a precise one. It invents concrete scenarios that force you to say where one concept ends and another begins, and when you describe how something works, it checks the code and flags any contradiction. Each settled term goes into GLOSSARY.md immediately, and the glossary holds definitions only, no implementation details. It offers an ADR only when a decision is hard to reverse, would puzzle a future reader, and came from a real trade-off. Files are created only once there's something to write in them; a large repo can keep one glossary per area.
Summarizes the skill at 5beb35b.
npx skills add https://github.com/mattpocock/skills --skill domain-modeling skills.sh pageSource on GitHubAll skills from mattpocock/skills
- Total Downloads
- 954,117 on skills.sh, Nov 9, 2026
- Repo stars
- 318,714 mattpocock/skills
- First seen
- Jun 4, 2026 on skills.sh
Weekly values
| Week to | Installs |
|---|---|
| Sep 21 | 43,132 |
| Sep 28 | 38,784 |
| Oct 5 | 43,499 |
| Oct 12 | 53,941 |
| Oct 19 | 43,971 |
| Oct 26 | 39,443 |
| Nov 2 | 36,477 |
| Nov 9 | 33,611 |
| Category |
Make the agent question you and write the plan down before it writes code. Everything for building software: planning, coding, debugging, design, frameworks, cloud, agents and skills. |
|---|---|
| Type |
A multi-step process the agent follows: interview, debug, run a TDD loop, review. |
| Effect |
Its own steps create or change files, git state or local tools. |
| Needs |
Instructions only. Works in any agent that supports skills. |
| Publisher |
Everyone else. Unverified vendor claims default to community. |
| Topics |
SKILL.md
From mattpocock/skills at 5beb35b. Checked daily, last changed Oct 20, 2026.
Frontmatter
name: domain-modeling
description: Build and sharpen a project's domain model. Use when discussing codebase terminology, writing or editing a GLOSSARY.md, or recording or editing an ADR.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. (Merely reading GLOSSARY.md for vocabulary is not this skill: that's a one-line habit any skill can do. This skill is for when you're changing the model, not just consuming it.)
File structure
Most repos have a single context:
/
├── GLOSSARY.md
├── docs/
│ └── adr/
│ ├── 0001-event-sourced-orders.md
│ └── 0002-postgres-for-write-model.md
└── src/
If a GLOSSARY-MAP.md exists at the root, the repo has multiple contexts. The map points to where each one lives:
/
├── GLOSSARY-MAP.md
├── docs/
│ └── adr/ ← system-wide decisions
├── src/
│ ├── ordering/
│ │ ├── GLOSSARY.md
│ │ └── docs/adr/ ← context-specific decisions
│ └── billing/
│ ├── GLOSSARY.md
│ └── docs/adr/
Create files lazily: only when you have something to write. If no GLOSSARY.md exists, create one when the first term is resolved. If no docs/adr/ exists, create it when the first ADR is needed.
During the session
Challenge against the glossary
When the user uses a term that conflicts with the existing language in GLOSSARY.md, call it out immediately. "Your glossary defines 'cancellation' as X, but you seem to mean Y. Which is it?"
Sharpen fuzzy language
When the user uses vague or overloaded terms, propose a precise canonical term. "You're saying 'account': do you mean the Customer or the User? Those are different things."
Discuss concrete scenarios
When domain relationships are being discussed, stress-test them with specific scenarios. Invent scenarios that probe edge cases and force the user to be precise about the boundaries between concepts.
Cross-reference with code
When the user states how something works, check whether the code agrees. If you find a contradiction, surface it: "Your code cancels entire Orders, but you just said partial cancellation is possible. Which is right?"
Update GLOSSARY.md inline
When a term is resolved, update GLOSSARY.md right there. Don't batch these up: capture them as they happen. Use the format in GLOSSARY-FORMAT.md.
GLOSSARY.md should be totally devoid of implementation details. Do not treat GLOSSARY.md as a spec, a scratch pad, or a repository for implementation decisions. It is a glossary and nothing else.
Offer ADRs sparingly
Only offer to create an ADR when all three are true:
- Hard to reverse: the cost of changing your mind later is meaningful
- Surprising without context: a future reader will wonder "why did they do it this way?"
- The result of a real trade-off: there were genuine alternatives and you picked one for specific reasons
If any of the three is missing, skip the ADR. Use the format in ADR-FORMAT.md.