Domain modeling plus

Domain Modeling Plus

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.

Runs alongside grill-me-plus sessions, wayfinder-plus grilling tickets, and to-spec-plus synthesis — anywhere terms get decided.

File structure

Most repos have a single context:

/
├── CONTEXT.md
├── docs/
│   └── adr/
│       ├── 0001-single-db-multi-tenancy.md
│       └── 0002-money-as-integer-minor-units.md
└── app/

If a CONTEXT-MAP.md exists at the root, the repo has multiple contexts. The map points to where each one lives — in a Laravel modular monolith that's the module root:

/
├── CONTEXT-MAP.md
├── docs/
│   └── adr/                              ← system-wide decisions
└── app/Domain/                           ← or modules/, app-modules/ — follow the repo
    ├── Ordering/
    │   ├── CONTEXT.md
    │   └── docs/adr/                     ← context-specific decisions
    └── Billing/
        ├── CONTEXT.md
        └── docs/adr/

Create files lazily — only when you have something to write. No CONTEXT.md? Create one when the first term is resolved. No docs/adr/? Create it when the first ADR is needed. Formats: references/context-format.md and references/adr-format.md.

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, resolve them through AskUserQuestion (Claude Code) or request_user_input (Codex): the candidate canonical terms as options, your recommendation first, each option's description saying what choosing it commits the model to. "You're saying 'account' — is that the Customer or the User?" is a click-to-answer decision, not an open-ended essay prompt. Fall back to asking in chat when no structured tool is available.

Discuss concrete scenarios

When domain relationships are being discussed, stress-test them with specific scenarios. Invent scenarios that probe edge cases and force precision about the boundaries between concepts: "A Customer with two Subscriptions cancels one mid-cycle — what happens to the Invoice already issued?"

Cross-reference with code

When the user states how something works, check whether the code agrees. In a Laravel codebase the model lives in more places than prose — check the glossary term against:

• Eloquent model and relationship names (app/Models, HasMany method names)
• Table and column names in migrations
• Enum cases (app/Enums)
• Policy names and ability strings
• Filament resource/page labels and navigation names
• Route names, job names, event names

If you find a contradiction, surface it: "Your code cancels entire Orders (Order::cancel()), but you just said partial cancellation is possible — which is right?" When a term is resolved against the code's current naming, the rename is real work — note it as a decision (and a ticket, if a tracker is in play), never silently absorb it.

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 references/context-format.md.

CONTEXT.md must stay totally devoid of implementation details. It is a glossary — not a spec, a scratch pad, or a home for implementation decisions.

Offer ADRs sparingly

Only offer to create an ADR when all three are true:

1. Hard to reverse — the cost of changing your mind later is meaningful
2. Surprising without context — a future reader will wonder "why did they do it this way?"
3. 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 references/adr-format.md.