/claude-md-writer

name: claude-md-writer
description: Use when creating or refactoring CLAUDE.md files - enforces best practices for size, structure, and content organization

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 | |---------|---------|