cc-create-rule

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• SKILL.md

SKILL.md (first lines)

# Create a Claude Code rule

A rule is a small markdown file in `.claude/rules/` that loads into context as instructions — same priority as `.claude/CLAUDE.md`, but split out by topic so things stay tidy. A rule can also be **path-scoped** so it only loads when Claude touches matching files, which saves context.

Three quick steps.

---

## Step 1 — Name the file by topic

One topic per file, descriptive name. It lives at `.claude/rules/<topic>.md`. Subfolders are fine (discovered recursively):

```
.claude/rules/
├── code-style.md
├── testing.md
├── security.md
└── frontend/
    └── components.md
```

## Step 2 — Decide the scope

Ask one question: **does this apply everywhere, or only to certain files?**

- **Everywhere** → no frontmatter. The rule loads at the start of every session.
- **Only certain files** → add `paths:` frontmatter with glob patterns. The rule loads only when Claude reads a file that matches — keeping it out of context until it's relevant.

When in doubt, scope it. A path-scoped rule is the lighter choice, and it's the main reason to use a rule over CLAUDE.md.

## Step 3 — Write it

Keep it like good CLAUDE.md content: short, specific, verifiable. Bullets over paragraphs. Aim well under ~50 lines.

**Always-on rule** (no frontmatter):

```markdown
# Testing

- Run `npm test` before committing.
- Co-locate tests next to the source file as `*.test.ts`.
- Mock network calls; never hit live services in unit tests.
```

**Path-scoped rule** (`paths:` frontmatter):

```markdown
---
paths:
  - "src/api/**/*.ts"
---

# API rules

- Every endpoint validates its input.
- Use the standard error response format.
- Include OpenAPI doc comments on each handler.
```

That's it — Claude Code discovers the file automatically. No wiring, no restart.

---

## Glob cheat sheet for `paths:`

| Pattern                  | Matches                                   |
| :----------------------- | :---------------------------------------- |
| `**/*.ts`                | all TypeScript files, any directory       |
| `src/**/*`               | everything under `src/`                    |
| `*.md`                   | markdown files in the project root only   |
| `src/components/*.tsx`   | React components in one specific directory |

Multiple patterns and brace expansion both work:

```markdown
---
paths:
  - "src/**/*.{ts,tsx}"
  - "tests/**/*.test.ts"
---
```

## Writing tips

- **Specific beats vague:** "Use 2-space indentation" lands better than "format code nicely."
- **No contradictions:** if two rules (or a rule and CLAUDE.md) disagree, Claude may pick one at random. Skim existing rules before adding.
- **Verify it loaded:** run `/memory` in Claude Code — it lists every CLAUDE.md and rules file in the session.

## Rule vs CLAUDE.md vs skill — quick pick

- **Rule** → a standing instruction, especially one that only matters for certain files. Loads automatically.
- **CLAUDE.md** → the few "always true everywhere" facts (build commands, layout, top conventions). Loads every session.
- **Skill** → a multi-step procedure or workflow you invoke. Loads on demand, not always in context.

If it's a procedure with steps, it's probably a skill. If it's a "do it this way" instruction, it's a rule.

From d3v0psdan/claude-skills, MIT.

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