| description | Build and sharpen a project's domain model. Use when the user wants to pin down domain terminology or a ubiquitous language, record an architectural decision, or when another skill needs to maintain the domain model.
|
| name | domain-modeling |
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 CONTEXT.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:
/
├── CONTEXT.md
├── docs/
│ └── adr/
│ ├── 0001-event-sourced-orders.md
│ └── 0002-postgres-for-write-model.md
└── src/
If a CONTEXT-MAP.md exists at the root, the repo has multiple contexts.
The map points to where each one lives:
/
├── CONTEXT-MAP.md
├── docs/
│ └── adr/ ← system-wide decisions
├── src/
│ ├── ordering/
│ │ ├── CONTEXT.md
│ │ └── docs/adr/ ← context-specific decisions
│ └── billing/
│ ├── CONTEXT.md
│ └── docs/adr/
Create files lazily - only when you have something to write. If no CONTEXT.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
CONTEXT.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 CONTEXT.md Inline
When a term is resolved, update CONTEXT.md right there. Don't batch these up -
capture them as they happen. Use the format in CONTEXT-FORMAT.md.
CONTEXT.md should be totally devoid of implementation details. Do not treat
CONTEXT.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.
