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define-language

Extract and formalize domain terminology from the current conversation into a consistent glossary, saved to specs/UBIQUITOUS_LANGUAGE_LATEST.md.

Distinct from model-domain and deepen-architecture: Use this skill to produce a canonical glossary of terms (words and definitions). Use model-domain to stress-test a plan through an interview that resolves domain model decisions. Use deepen-architecture to find module-level refactoring opportunities in the codebase.

HARD GATE — Ubiquitous language is NOT optional. Every term in the domain that could be misunderstood must be glossed. Ambiguity = rework.

  1. Scan the conversation for domain-relevant nouns, verbs, and concepts
  2. Identify problems:
    • Same word used for different concepts (ambiguity)
    • Different words used for the same concept (synonyms)
    • Vague or overloaded terms
  3. Propose a canonical glossary with opinionated term choices
  4. Write to specs/UBIQUITOUS_LANGUAGE_LATEST.md in the working directory using the format below
  5. Output a summary inline in the conversation

Write a specs/UBIQUITOUS_LANGUAGE_LATEST.md file with this structure:

# Ubiquitous Language
## Order lifecycle
| Term | Definition | Aliases to avoid |
| ----------- | ------------------------------------------------------- | --------------------- |
| **Order** | A customer's request to purchase one or more items | Purchase, transaction |
| **Invoice** | A request for payment sent to a customer after delivery | Bill, payment request |
## People
| Term | Definition | Aliases to avoid |
| ------------ | ------------------------------------------- | ---------------------- |
| **Customer** | A person or organization that places orders | Client, buyer, account |
| **User** | An authentication identity in the system | Login, account |
## Relationships
- An **Invoice** belongs to exactly one **Customer**
- An **Order** produces one or more **Invoices**
## Example dialogue
> **Dev:** "When a **Customer** places an **Order**, do we create the **Invoice** immediately?"
> **Domain expert:** "No — an **Invoice** is only generated once a **Fulfillment** is confirmed."
## Flagged ambiguities
- "account" was used to mean both **Customer** and **User** — these are distinct concepts.
  • Be opinionated. When multiple words exist for the same concept, pick the best one and list the others as aliases to avoid.
  • Flag conflicts explicitly. If a term is used ambiguously, call it out in “Flagged ambiguities” with a clear recommendation.
  • Only include terms relevant for domain experts. Skip names of modules or classes unless they have domain meaning.
  • Keep definitions tight. One sentence max. Define what it IS, not what it does.
  • Show relationships. Use bold term names and express cardinality where obvious.
  • Group terms into multiple tables when natural clusters emerge. One table is fine if terms are cohesive.
  • Write an example dialogue. 3–5 exchanges between a dev and domain expert showing terms used precisely.

When invoked again in the same conversation:

  1. Read the existing specs/UBIQUITOUS_LANGUAGE_LATEST.md
  2. Incorporate any new terms from subsequent discussion
  3. Update definitions if understanding has evolved
  4. Re-flag any new ambiguities
  5. Rewrite the example dialogue to incorporate new terms