CLAUDE.md Writer

Creates and refactors CLAUDE.md files following official Anthropic best practices (2025).

Golden Rules

Rule	Why
CLAUDE.md < 200 lines	Loads on EVERY request, costs tokens
Rules files < 500 lines each	Official recommendation per file
Critical rules FIRST	Top = highest priority
Modular rules → .claude/rules/	Conditional loading, organized
Use paths: frontmatter	Load rules only for matching files
No linting rules	Use ESLint/Prettier/Biome instead
Pointers over copies	Files change, references stay valid

Memory Hierarchy

Claude Code loads memory in this order (higher = higher priority):

Priority	Type	Location
Highest	Enterprise	/Library/Application Support/ClaudeCode/CLAUDE.md
↓	Project	./CLAUDE.md or ./.claude/CLAUDE.md
↓	Rules	./.claude/rules/*.md (conditional)
↓	User	~/.claude/CLAUDE.md
Lowest	Local	./CLAUDE.local.md (gitignored)

Use /memory command to see currently loaded files.

3-Tier Documentation System

Official recommendation for large projects:

Tier	Location	Loads	Target
1. Foundation	CLAUDE.md	Always	< 200 lines
2. Component	.claude/rules/{component}/	When working in component	< 500 lines
3. Feature	Co-located with code	When working on feature	As needed

Example structure:

.claude/
├── CLAUDE.md                 # Tier 1: always loaded
└── rules/
    ├── database.md           # Tier 2: SQL, migrations
    ├── api.md                # Tier 2: API patterns
    └── frontend/             # Tier 2: subdirectory
        ├── components.md     # paths: src/**/*.tsx
        ├── layout.md         # paths: src/pages/**/*.tsx
        └── tokens.md         # paths: **/*.tsx

Structure Template

# Project Name

One-line description.

## Commands

- `npm run dev` - Development
- `npm run build` - Production
- `npm run test` - Tests

## Architecture

| Path | Purpose |
|------|---------|
| `lib/` | Core logic |
| `app/api/` | API routes |

## Key Patterns

**Pattern Name**: One-line explanation.

## Database (if applicable)

| Table | Key Fields |
|-------|------------|

## Modular Docs

See `.claude/rules/` for:
- `database.md` - queries, schema
- `deploy.md` - deployment

## Tech Stack

One line: Next.js 15, PostgreSQL, TypeScript

Conditional Rules (Path-Specific)

Use YAML frontmatter for file-type-specific rules:

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

# API Rules

- All endpoints must validate input
- Use standard error format

Glob Patterns

Pattern	Matches
**/*.ts	All .ts files anywhere
src/**/*	All files under src/
*.md	Markdown in project root
src/components/*.tsx	Components in specific dir

Combining Patterns

# Multiple extensions
paths: "src/**/*.{ts,tsx}"

# Multiple directories
paths: "{src,lib}/**/*.ts, tests/**/*.test.ts"

Note: Wrap patterns in quotes for YAML safety.

Rules with paths: only load when working with matching files → saves tokens.

Workflow: New Project

1. Run /init for base CLAUDE.md
2. Review and trim generated content
3. Identify critical rules — what breaks if ignored?
4. Create .claude/rules/ for domain-specific docs
5. Keep main file < 100 lines

Workflow: Refactor Existing

1. Count lines — if > 300, must split
2. Find task-specific content — SQL, debugging, deploy → extract
3. Create .claude/rules/:
   • database.md - queries, schema, connection
   • deploy.md - deployment process
   • messaging.md - integrations (Telegram, etc.)
4. Use @file references — don't duplicate
5. Keep in CLAUDE.md — only what applies to EVERY task

What Goes Where

Content	Location
Project description	CLAUDE.md
Critical constraints	CLAUDE.md (top!)
Quick start (3 commands)	CLAUDE.md
Architecture overview	CLAUDE.md
Key patterns (1-liners)	CLAUDE.md
SQL queries/schema	.claude/rules/database.md
Deployment steps	.claude/rules/deploy.md
API documentation	.claude/rules/api.md
Git workflow	.claude/rules/git.md
Personal preferences	CLAUDE.local.md (gitignored)
Code style rules	.eslintrc / biome.json (NOT docs)

Import Syntax

Reference files instead of duplicating:

@README.md
@docs/architecture.md
@~/.claude/snippets/common.md

• Relative: @docs/file.md
• Absolute: @~/path/file.md
• Max depth: 5 hops

CLAUDE.local.md

Personal project settings (auto-gitignored):

# My Local Settings

- Prefer verbose output
- Run tests after every change
- My worktree location: .trees/

Common Mistakes

Mistake	Fix
500+ lines	Split into .claude/rules/
SQL examples inline	→ rules/database.md
"Run prettier" rules	Use tool config files
Full API docs	→ rules/api.md
Deployment instructions	→ rules/deploy.md
Code in CLAUDE.md	Use @file:line references
Negative rules only	Add alternatives: "Don't X; use Y instead"

Quality Checklist

Before finishing:

• CLAUDE.md < 200 lines?
• Each rules file < 500 lines?
• Critical rules at top?
• No task-specific content in main file?
• No code style rules (use ESLint/Prettier)?
• .claude/rules/ for domain-specific docs?
• Subdirectories for components (frontend/, backend/)?
• paths: frontmatter for conditional loading?
• @ references instead of duplication?
• CLAUDE.local.md for personal prefs?

Useful Commands

Command	Purpose
/init	Generate initial CLAUDE.md
/memory	View loaded memory files

Sources

Official:

• code.claude.com/docs/en/memory (Memory management, paths, globs)
• anthropic.com/engineering/claude-code-best-practices
• claude.com/blog/using-claude-md-files

Community:

• thedocumentation.org/claude-code-development-kit (3-Tier System)
• claudefa.st/blog/guide/mechanics/rules-directory
• humanlayer.dev/blog/writing-a-good-claude-md

Updated: Jan 2026