Domain 2 · 20%% of exam

Path-scoped rules with .claude/rules/

How to keep instructions out of context until they are relevant.

4 min read · Lesson 4 of 11 in this domain

A root CLAUDE.md loads on every single session, so anything you put there costs context in every unrelated conversation. Rules files solve that. Dropping a markdown file into .claude/rules/ gives you the same instruction mechanism, but adding a paths glob in its frontmatter makes it conditional: the rule enters context only when Claude works with a file that matches. It is the difference between telling someone your API conventions every morning and handing them the note when they open the API folder.

Key points

Put markdown files in .claude/rules/. All .md files are discovered recursively, so you can organise into subdirectories.
A rule without a paths field loads unconditionally at launch, at the same priority as .claude/CLAUDE.md.
A rule with paths frontmatter loads only when Claude works with files matching those globs. This is the mechanism for scoping instructions by file type or directory.
Path-scoped rules trigger when Claude reads a matching file, not on every tool use.
User-level rules live in ~/.claude/rules/ and load before project rules, giving project rules higher priority.
Rules vs skills: rules load every session (or on path match); skills load only when invoked or judged relevant.

A path-scoped rule

---
paths:
  - "src/api/**/*.ts"
  - "lib/**/*.{ts,tsx}"
---

# API Development Rules
- All API endpoints must include input validation
- Use the standard error response format

Exam trap

"Put a conditional sentence in the root CLAUDE.md" — that loads on every session regardless, costing context in every unrelated conversation.

Check your understanding

How do you load a rule only for TypeScript files under src/api/?

Correct answer: A — A paths glob in .claude/rules/ frontmatter
Path-scoped rules are the purpose-built mechanism; a root CLAUDE.md loads every session regardless.

A rules file has no paths field. When does it load?

Correct answer: B — At launch, unconditionally
Omitting paths is the normal way to write an always-on rule.

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The CLAUDE.md hierarchy and load order

Imports, AGENTS.md and exclusions

Source: Claude Code Docs — Memory · Independent study aid, not affiliated with or endorsed by Anthropic.