Repomix Skill

Repomix is a powerful tool that packs entire repositories into single, AI-friendly files. Perfect for when you need to feed codebases to Large Language Models (LLMs) or other AI tools like Claude, ChatGPT, and Gemini.

When to Use This Skill

Use this skill when:

• User needs to package a codebase for AI analysis
• Preparing repository context for LLM consumption
• Generating codebase snapshots for documentation
• Analyzing third-party libraries or repositories
• Creating AI-friendly representations of code projects
• Investigating bugs across large codebases
• Performing security audits on repositories
• Generating context for implementation planning

Core Capabilities

1. Repository Packaging

Repomix packages entire repositories into single files with:

• AI-optimized formatting with clear separators
• Multiple output formats (XML, Markdown, JSON, Plain text)
• Git-aware processing (respects .gitignore)
• Token counting for LLM context management
• Security checks for sensitive information

2. Remote Repository Support

Can process remote repositories without cloning:

• Shorthand: npx repomix --remote yamadashy/repomix
• Full URL: npx repomix --remote https://github.com/owner/repo
• Specific commits: npx repomix --remote https://github.com/owner/repo/commit/hash

3. Comment Removal

Strips comments from supported languages when needed:

• Supported: HTML, CSS, JavaScript, TypeScript, Vue, Svelte, Python, PHP, Ruby, C, C#, Java, Go, Rust, Swift, Kotlin, Dart, Shell, YAML
• Enable with: --remove-comments or config file

Installation

Check if installed first:

repomix --version

Install using preferred method:

# npm
npm install -g repomix

# yarn
yarn global add repomix

# bun
bun add -g repomix

# Homebrew (macOS/Linux)
brew install repomix

Basic Usage

Package Current Directory

# Basic packaging (generates repomix-output.xml)
repomix

# Specify output format
repomix --style markdown
repomix --style json
repomix --style plain

# Custom output path
repomix -o custom-output.xml

Package Specific Directory

repomix /path/to/directory

Package Remote Repository

# Shorthand format
npx repomix --remote owner/repo

# Full URL
npx repomix --remote https://github.com/owner/repo

# Specific commit
npx repomix --remote https://github.com/owner/repo/commit/abc123

Command Line Options

File Selection

# Include specific patterns
repomix --include "src/**/*.ts,*.md"

# Ignore additional patterns
repomix -i "tests/**,*.test.js"

# Disable .gitignore rules
repomix --no-gitignore

# Disable default ignore patterns
repomix --no-default-patterns

Output Configuration

# Output format
repomix --style markdown  # or xml, json, plain

# Output file path
repomix -o output.md

# Remove comments
repomix --remove-comments

# Show line numbers
repomix --no-line-numbers  # disable line numbers

Security & Analysis

# Run security checks
repomix --no-security-check  # disable security scanning

# Copy to clipboard
repomix --copy  # copy output to clipboard

# Verbose output
repomix --verbose

Configuration

# Use custom config file
repomix -c custom-config.json

# Initialize new config
repomix --init  # creates repomix.config.json

Configuration File

Create repomix.config.json in project root:

{
  "output": {
    "filePath": "repomix-output.xml",
    "style": "xml",
    "removeComments": false,
    "showLineNumbers": true,
    "copyToClipboard": false
  },
  "include": ["**/*"],
  "ignore": {
    "useGitignore": true,
    "useDefaultPatterns": true,
    "customPatterns": [
      "additional-folder",
      "**/*.log",
      "**/tmp/**"
    ]
  },
  "security": {
    "enableSecurityCheck": true
  }
}

Ignore Patterns

.repomixignore File

Create .repomixignore for Repomix-specific ignore patterns (same format as .gitignore):

# Build artifacts
dist/
build/
*.min.js

# Test files
**/*.test.ts
**/*.spec.ts
coverage/

# Large files
*.mp4
*.zip

# Sensitive files
.env*
secrets/

Precedence Order

1. CLI ignore patterns (-i flag)
2. .repomixignore file
3. Custom patterns in config file
4. .gitignore file (if enabled)
5. Default patterns (if enabled)

Output Formats

XML Format (Default)

Best for structured AI consumption:

repomix --style xml

Markdown Format

Human-readable with syntax highlighting:

repomix --style markdown

JSON Format

For programmatic processing:

repomix --style json

Plain Text

Simple concatenation:

repomix --style plain

Use Cases & Examples

1. Code Review Preparation

# Package feature branch for AI review
repomix --include "src/**/*.ts" --remove-comments -o feature-review.md --style markdown

2. Security Audit

# Package third-party library for analysis
npx repomix --remote vendor/library --style xml -o audit.xml

3. Documentation Generation

# Package with docs and code
repomix --include "src/**,docs/**,*.md" --style markdown -o context.md

4. Bug Investigation

# Package specific modules
repomix --include "src/auth/**,src/api/**" -o debug-context.xml

5. Implementation Planning

# Full codebase context for planning
repomix --remove-comments --copy

Token Management

Repomix automatically counts tokens for:

• Individual files
• Total repository
• Per-format output

Use token counts to manage LLM context limits:

• Claude: ~200K tokens
• GPT-4: ~128K tokens
• GPT-3.5: ~16K tokens

Security Considerations

Sensitive Data Detection

Repomix uses Secretlint to detect:

• API keys and tokens
• Passwords and credentials
• Private keys
• AWS secrets
• Database connection strings

Disable if needed:

repomix --no-security-check

Best Practices

1. Always review output before sharing
2. Use .repomixignore for sensitive files
3. Enable security checks for unknown codebases
4. Avoid packaging .env files
5. Check for hardcoded credentials

Performance Optimization

Large Repositories

Repomix uses worker threads for parallel processing:

• Efficiently handles large codebases
• Example: facebook/react processed 29x faster (123s → 4s)

Optimization Tips

# Exclude unnecessary files
repomix -i "node_modules/**,dist/**,*.min.js"

# Process specific directories only
repomix --include "src/**/*.ts"

# Disable line numbers for smaller output
repomix --no-line-numbers

Workflow Integration

With Claude Code

# Package and analyze in one workflow
repomix --style markdown --copy
# Then paste into Claude for analysis

With CI/CD

# Generate codebase snapshot for releases
repomix --style markdown -o release-snapshot.md

With Git Hooks

# Pre-commit hook to generate context
repomix --include "src/**" -o .context/latest.xml

Common Patterns

Full Repository Package

repomix --remove-comments --style markdown -o full-repo.md

Source Code Only

repomix --include "src/**/*.{ts,tsx,js,jsx}" -i "**/*.test.*"

Documentation Bundle

repomix --include "**/*.md,docs/**" --style markdown

TypeScript Project

repomix --include "**/*.ts,**/*.tsx" --remove-comments --no-line-numbers

Remote Analysis

npx repomix --remote owner/repo --style xml -o analysis.xml

Troubleshooting

Issue: Output Too Large

# Exclude unnecessary files
repomix -i "node_modules/**,dist/**,coverage/**"

# Process specific directories
repomix --include "src/**"

Issue: Missing Files

# Disable .gitignore rules
repomix --no-gitignore

# Check ignore patterns
cat .repomixignore

Issue: Sensitive Data Warnings

# Review flagged files
# Add to .repomixignore
# Or disable checks: --no-security-check

Implementation Workflow

When user requests repository packaging:

1. Assess Requirements

   • Identify target repository (local/remote)
   • Determine output format needed
   • Check for sensitive data concerns

2. Configure Filters

   • Set include patterns for relevant files
   • Add ignore patterns for unnecessary files
   • Enable/disable comment removal

3. Execute Packaging

   • Run repomix with appropriate options
   • Monitor token counts
   • Verify security checks

4. Validate Output

   • Review generated file
   • Confirm no sensitive data
   • Check token limits for target LLM

5. Deliver Context

   • Provide packaged file to user
   • Include token count summary
   • Note any warnings or issues

Best Practices

1. Start with defaults: Run basic repomix first, then refine
2. Use .repomixignore: Better than CLI flags for complex patterns
3. Enable security checks: Especially for third-party code
4. Choose right format: XML for AI, Markdown for humans
5. Monitor token counts: Stay within LLM limits
6. Remove comments: When focusing on logic over documentation
7. Version output: Include in .gitignore, regenerate as needed
8. Test patterns: Verify include/exclude work as expected

Related Tools

• Context7: For up-to-date library documentation
• Git: For repository history analysis
• Secretlint: For security scanning
• Token counters: For LLM context management

Additional Resources

• GitHub: https://github.com/yamadashy/repomix
• Documentation: https://repomix.com/guide/
• MCP Server: Available for AI assistant integration
• Claude Code Plugin: Official integration available