Domain Modeling Agent Skill

domain-modeling

Most misbuilds start as a language gap: the agent is dropped into a project

and left to infer the jargon, so it uses twenty words where the domain has

one. A shared language closes the gap. When code, conversation, and the model

all draw from the same vocabulary, names line up, navigation gets cheaper, and

the model spends fewer tokens reasoning because it has a tighter language to

reason in.

Method

• Harvest the terms. From the request, the codebase, and the user's own

words, list the nouns and verbs that carry domain meaning - the concepts a

newcomer would have to ask about. Prefer the user's word over a synonym you

like better.

• Pin each one. Write a one-line definition in the project's own language,

not a dictionary definition. If two terms blur together, force the

distinction or collapse them - ambiguity here becomes inconsistent names in

code.

• Draw the boundaries. Where the same word means different things in

different parts of the system, that is a boundary. Name each context and

note which terms belong to it. A term that means two things is two terms.

• Record the hard calls. When a modeling choice was contested or will be

questioned later, write a short decision record: context, choice,

alternatives rejected, why.

Outputs

• CONTEXT.md - the shared-language glossary. One term per line:

term - what it means in this project. Grouped by bounded context when

there is more than one. Point every future session at this file. On re-run,

add new terms and update definitions that changed; do not rewrite the file

wholesale.

• Bounded-context sketch - the contexts and which terms live in each,

short enough to read in fifteen seconds.

• Decision records in docs/decisions/NNNN-slug.md for the contested

modeling calls only. Read the directory first and number from the highest

existing record so two records never collide. Skip the obvious ones.

Guardrails

• The glossary is for the model as much as the human - write it to be loaded,

not framed on a wall.

• Do not invent terms the project does not use. Reflect the domain; do not

rename it.

• Keep it small and current. A glossary that lists everything and updates

nothing is worse than none. Prune terms that fall out of use.

Where it fits

Run this before plan-interrogate on a new area, or let plan-interrogate

call back here when it hits terms it cannot pin. The CONTEXT.md this produces

is the same file plan-interrogate emits - one shared-language artifact, two

ways in.