Windsurf rules

1---
2name: model-domain
3model: sonnet
4description: "Grilling session that challenges your plan against the existing domain model, sharpens terminology, and updates specs/tech-architecture/tech-stack.md and specs/adr/ inline as decisions crystallise. Use when user wants to stress-test a plan against their project's domain language and documented decisions."
5---
6 
7# Model Domain
8 
9**Distinct from `define-language` and `deepen-architecture`:** Use this skill to stress-test a plan through a grilling interview that resolves domain model decisions and captures invariants. Use `define-language` to produce a canonical glossary of terms. Use `deepen-architecture` to find module-level refactoring opportunities in code.
10 
11Interview me relentlessly about every aspect of this plan until we reach a shared understanding. Walk down each branch of the design tree, resolving dependencies between decisions one-by-one. For each question, provide your recommended answer.
12 
13> **HARD GATE** — Capture invariants (what MUST always be true) and state machines (what transitions are legal) for core entities. If these are fuzzy, design will fail.
14 
15Ask the questions one at a time, waiting for feedback on each question before continuing.
16 
17If a question can be answered by exploring the codebase, explore the codebase instead.
18 
19## Domain awareness
20 
21During codebase exploration, also look for existing documentation:
22 
23### File structure
24 
25Most repos have a single context:
26 
27```
28/
29├── specs/
30│   ├── CONTEXT.md
31│   └── adr/
32│       ├── 0001-event-sourced-orders.md
33│       └── 0002-postgres-for-write-model.md
34└── src/
35```
36 
37If a `specs/tech-architecture/tech-stack.md` exists, the repo has multiple contexts. The map points to where each one lives:
38 
39```
40/
41├── specs/
42│   ├── CONTEXT-MAP.md
43│   └── adr/                          ← system-wide decisions
44└── src/
45    ├── ordering/
46    │   └── specs/
47    │       ├── CONTEXT.md
48    │       └── adr/                  ← context-specific decisions
49    └── billing/
50        └── specs/
51            ├── CONTEXT.md
52            └── adr/
53```
54 
55Create files lazily — only when you have something to write. If no `specs/tech-architecture/tech-stack.md` exists, create it when the first term is resolved. If no `specs/adr/` exists, create it when the first ADR is needed.
56 
57## During the session
58 
59### Challenge against the glossary
60 
61When the user uses a term that conflicts with the existing language in `specs/tech-architecture/tech-stack.md`, call it out immediately. "Your glossary defines 'cancellation' as X, but you seem to mean Y — which is it?"
62 
63### Sharpen fuzzy language
64 
65When 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."
66 
67### Discuss concrete scenarios
68 
69When 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.
70 
71### Cross-reference with code
72 
73When 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?"
74 
75### Update specs/tech-architecture/tech-stack.md inline
76 
77When a term is resolved, update `specs/tech-architecture/tech-stack.md` right there. Don't batch these up — capture them as they happen. Use the format in [CONTEXT-FORMAT.md](./CONTEXT-FORMAT.md).
78 
79Don't couple `specs/tech-architecture/tech-stack.md` to implementation details. Only include terms that are meaningful to domain experts.
80 
81### Offer ADRs sparingly
82 
83Only offer to create an ADR when all three are true:
84 
851. **Hard to reverse** — the cost of changing your mind later is meaningful
862. **Surprising without context** — a future reader will wonder "why did they do it this way?"
873. **The result of a real trade-off** — there were genuine alternatives and you picked one for specific reasons
88 
89If any of the three is missing, skip the ADR. Use the format in [ADR-FORMAT.md](./ADR-FORMAT.md).
90 
91## Concurrency safety audit
92 
93When the plan touches shared state, async, or multi-threaded code:
94 
95- [ ] List every **shared mutable** location (globals, singletons, module-level caches).
96- [ ] For each: who reads, who writes, synchronization mechanism (lock, actor, immutable copy).
97- [ ] Flag **race risks** (check-then-act, non-atomic read-modify-write) with severity.
98- [ ] Record findings in `specs/tech-architecture/tech-stack.md` under `## Concurrency` or in an ADR if architectural.
99 
100 
101 
102<!-- story: e07s03 -->
103 
104---
105 
106# ADR Format
107 
108ADRs live in `docs/adr/` and use sequential numbering: `0001-slug.md`, `0002-slug.md`, etc.
109 
110Create the `docs/adr/` directory lazily — only when the first ADR is needed.
111 
112## Template
113 
114```md
115# {Short title of the decision}
116 
117{1-3 sentences: what's the context, what did we decide, and why.}
118```
119 
120That's it. An ADR can be a single paragraph. The value is in recording *that* a decision was made and *why* — not in filling out sections.
121 
122## Optional sections
123 
124Only include these when they add genuine value. Most ADRs won't need them.
125 
126- **Status** frontmatter (`proposed | accepted | deprecated | superseded by ADR-NNNN`) — useful when decisions are revisited
127- **Considered Options** — only when the rejected alternatives are worth remembering
128- **Consequences** — only when non-obvious downstream effects need to be called out
129 
130## Numbering
131 
132Scan `docs/adr/` for the highest existing number and increment by one.
133 
134## When to offer an ADR
135 
136All three of these must be true:
137 
1381. **Hard to reverse** — the cost of changing your mind later is meaningful
1392. **Surprising without context** — a future reader will look at the code and wonder "why on earth did they do it this way?"
1403. **The result of a real trade-off** — there were genuine alternatives and you picked one for specific reasons
141 
142If a decision is easy to reverse, skip it — you'll just reverse it. If it's not surprising, nobody will wonder why. If there was no real alternative, there's nothing to record beyond "we did the obvious thing."
143 
144### What qualifies
145 
146- **Architectural shape.** "We're using a monorepo." "The write model is event-sourced, the read model is projected into Postgres."
147- **Integration patterns between contexts.** "Ordering and Billing communicate via domain events, not synchronous HTTP."
148- **Technology choices that carry lock-in.** Database, message bus, auth provider, deployment target. Not every library — just the ones that would take a quarter to swap out.
149- **Boundary and scope decisions.** "Customer data is owned by the Customer context; other contexts reference it by ID only." The explicit no-s are as valuable as the yes-s.
150- **Deliberate deviations from the obvious path.** "We're using manual SQL instead of an ORM because X." Anything where a reasonable reader would assume the opposite. These stop the next engineer from "fixing" something that was deliberate.
151- **Constraints not visible in the code.** "We can't use AWS because of compliance requirements." "Response times must be under 200ms because of the partner API contract."
152- **Rejected alternatives when the rejection is non-obvious.** If you considered GraphQL and picked REST for subtle reasons, record it — otherwise someone will suggest GraphQL again in six months.
153 
154---
155 
156# CONTEXT.md Format
157 
158## Structure
159 
160```md
161# {Context Name}
162 
163{One or two sentence description of what this context is and why it exists.}
164 
165## Language
166 
167**Order**:
168A customer's request to purchase one or more items.
169_Avoid_: Purchase, transaction
170 
171**Invoice**:
172A request for payment sent to a customer after delivery.
173_Avoid_: Bill, payment request
174 
175**Customer**:
176A person or organization that places orders.
177_Avoid_: Client, buyer, account
178 
179## Relationships
180 
181- An **Order** produces one or more **Invoices**
182- An **Invoice** belongs to exactly one **Customer**
183 
184## Example dialogue
185 
186> **Dev:** "When a **Customer** places an **Order**, do we create the **Invoice** immediately?"
187> **Domain expert:** "No — an **Invoice** is only generated once a **Fulfillment** is confirmed."
188 
189## Flagged ambiguities
190 
191- "account" was used to mean both **Customer** and **User** — resolved: these are distinct concepts.
192```
193 
194## Rules
195 
196- **Be opinionated.** When multiple words exist for the same concept, pick the best one and list the others as aliases to avoid.
197- **Flag conflicts explicitly.** If a term is used ambiguously, call it out in "Flagged ambiguities" with a clear resolution.
198- **Keep definitions tight.** One sentence max. Define what it IS, not what it does.
199- **Show relationships.** Use bold term names and express cardinality where obvious.
200- **Only include terms specific to this project's context.** General programming concepts (timeouts, error types, utility patterns) don't belong even if the project uses them extensively. Before adding a term, ask: is this a concept unique to this context, or a general programming concept? Only the former belongs.
201- **Group terms under subheadings** when natural clusters emerge. If all terms belong to a single cohesive area, a flat list is fine.
202- **Write an example dialogue.** A conversation between a dev and a domain expert that demonstrates how the terms interact naturally and clarifies boundaries between related concepts.
203 
204## Single vs multi-context repos
205 
206**Single context (most repos):** One `CONTEXT.md` at the repo root.
207 
208**Multiple contexts:** A `CONTEXT-MAP.md` at the repo root lists the contexts, where they live, and how they relate to each other:
209 
210```md
211# Context Map
212 
213## Contexts
214 
215- Ordering — `src/ordering/CONTEXT.md` — receives and tracks customer orders
216- Billing — `src/billing/CONTEXT.md` — generates invoices and processes payments
217- Fulfillment — `src/fulfillment/CONTEXT.md` — manages warehouse picking and shipping
218 
219## Relationships
220 
221- **Ordering → Fulfillment**: Ordering emits `OrderPlaced` events; Fulfillment consumes them to start picking
222- **Fulfillment → Billing**: Fulfillment emits `ShipmentDispatched` events; Billing consumes them to generate invoices
223- **Ordering ↔ Billing**: Shared types for `CustomerId` and `Money`
224```
225 
226The skill infers which structure applies:
227 
228- If `CONTEXT-MAP.md` exists, read it to find contexts
229- If only a root `CONTEXT.md` exists, single context
230- If neither exists, create a root `CONTEXT.md` lazily when the first term is resolved
231 
232When multiple contexts exist, infer which one the current topic relates to. If unclear, ask.
233