This entry duplicates principle-model-the-domain, which is the one we list in search.

principle-model-the-domain

Apply when writing stateful logic, or when code branches a lot or repeats a shape assumption across files.

Skill by n3m6

IndexedGPL-3.0★ 19

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Works with Claude Code, Claude apps, Codex, Cursor, Gemini CLI, GitHub Copilot, VS Code, OpenCode, Goose, Windsurf. Read the repository before you give any tool access to your data.

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About

Apply when writing stateful logic, or when code branches a lot or repeats a shape assumption across files. Encode the domain in a structure instead of scattered conditionals.

Use cases: writing, agent-building

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What's inside

Skill name: principle-model-the-domain
Description: Apply when writing stateful logic, or when code branches a lot or repeats a shape assumption across files. Encode the domain in a structure instead of scattered conditionals.
License: GPL-3.0
Metadata: opencode/autoinvoke: false
Instructions: 22 lines in SKILL.md · view on GitHub

Files (1)

SKILL.md

SKILL.md (first lines)

# 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. 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 sign 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 sign. Phase-named modules repeat the same domain rules across steps.

From n3m6/opencode-config, GPL-3.0.

Signals

Stars: 19
Forks: 2
Open issues: 1
Last commit (this folder): Oct 6, 2026 (22 days ago)

From GitHub (fetched Oct 24, 2026).

Details

License: GPL-3.0
Repository: github.com/n3m6/opencode-config
First seen: Oct 24, 2026
Last checked: Oct 24, 2026
Source: GitHub github-graphql

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principle-model-the-domain skill. Agent Mart. https://agentmart.dev/skills/n3m6-principle-model-the-domain (last updated 2026-10-24)