principle-model-the-domain

principle-model-the-domain is a skill for Claude Code from J-StaR-Films-Studios/VibeCode-Protocol-Suite. It costs 39 tokens per session (421 once invoked), scanned A, a copy of principle-model-the-domain, ISC.

A code-design guideline for representing a problem's rules in a clear structure instead of repeating assumptions across many conditions and files.

In plain words
What is it for?
Use it when modeling business rules, state transitions, or repeated data shapes.
Why use it?
It reduces duplicated logic and makes stateful, branching code easier to change safely.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

Good fit Use it when modeling business rules, state transitions, or repeated data shapes.

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Install with agentmods
npx agentmods add skills/j-star-films-studios/vibecode-protocol-suite/model-the-domain
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add J-StaR-Films-Studios/VibeCode-Protocol-Suite --skill model-the-domain
Clone the repo
git clone --depth 1 https://github.com/J-StaR-Films-Studios/VibeCode-Protocol-Suite

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for principle-model-the-domain

README.md
[![agentmods](https://agentmods.dev/badge/skills/j-star-films-studios/vibecode-protocol-suite/model-the-domain/github.svg)](https://agentmods.dev/skills/j-star-films-studios/vibecode-protocol-suite/model-the-domain)
Your own site
<a href="https://agentmods.dev/skills/j-star-films-studios/vibecode-protocol-suite/model-the-domain"><img src="https://agentmods.dev/badge/skills/j-star-films-studios/vibecode-protocol-suite/model-the-domain/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for principle-model-the-domain

Your own site · 80×15
<a href="https://agentmods.dev/skills/j-star-films-studios/vibecode-protocol-suite/model-the-domain"><img src="https://agentmods.dev/badge/skills/j-star-films-studios/vibecode-protocol-suite/model-the-domain.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 421 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00039 $0.00421
Opus 5 $0.00019 $0.00211
Sonnet 5 $0.00008 $0.00084
Haiku 4.5 $0.00004 $0.00042

Measured 9d ago against content hash 6b359783c5c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

principle-model-the-domain scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to principle-model-the-domain — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

assets/.agent/skills/engineering-principles/model-the-domain/SKILL.md · 27 lines

What it actually says

Model the Domain

Encode the real domain in a data structure instead of scattering it across conditionals.

Why: Scattered booleans, repeated shape assumptions, and branching spread across files are accidental complexity. A structure that matches the domain makes invalid states unrepresentable and deletes branches. Choosing it at write time is cheap; recovering it later reads as a refactor and gets deferred.

Reach for structures like these:

  • A state machine instead of scattered booleans, phases, or lifecycle checks.
  • A typed object/model instead of loose parameters or repeated shape assumptions.
  • A map, registry, lookup table, or discriminated union instead of branching spread across files.
  • A reducer or command/event model instead of ad hoc state mutations.
  • A module organized around one body of domain knowledge instead of a sequence such as load, validate, transform, and save. Execution order is not ownership.
  • A small module boundary that gathers repeated behavior, ownership, or invariants.
  • A queue, cache, index, graph/tree, or normalized collection where the data access pattern calls for it.
  • Any other structure that fits. The list above covers the common cases only. When none fits, work out what the code must never allow and how the data gets read, then find the structure that encodes exactly that.

Do not force an abstraction. Prefer boring code if the current shape is already clear, local, and unlikely to grow. Be skeptical of an abstraction that adds indirection without removing branches, duplicated rules, invalid states, or lifecycle risk.

The tell that you skipped this is a new feature that grows an existing if/else chain by one more branch, or a second boolean that must stay in sync with the first. Temporal decomposition is another tell. Phase-named modules repeat the same domain rules across steps.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 27 lines · 39 tokens per session scan A 6b359783c5c9

Subscribe to this mod's changes

principle-model-the-domain is a skill published in the GitHub repository J-StaR-Films-Studios/VibeCode-Protocol-Suite (24 stars, last pushed yesterday), licensed ISC. It adds 39 tokens to every session and 421 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to principle-model-the-domain, differing in 0 lines, and is treated as a copy.

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