Codebase Analysis Skill

Analyze codebases systematically and create comprehensive CLAUDE.md/AGENTS.md files that help future AI instances understand the project.

When to use

Trigger this skill when:

• User asks "analyze this codebase" / "创建CLAUDE.md" / "create AGENTS.md"
• User wants to understand a project's structure and conventions
• User asks to create documentation for AI agents
• User says "Please analyze this codebase and create a CLAUDE.md file"

Workflow

1. Project Discovery

# List root directory
ls -la

# Check for existing docs
cat README.md
cat package.json
cat go.mod
cat Cargo.toml

# Find source directories
find . -type f -name "*.ts" -o -name "*.js" -o -name "*.go" -o -name "*.py" | head -20

2. Architecture Analysis

Identify:

• Language(s): TypeScript, Go, Python, etc.
• Framework(s): React, Express, Gin, etc.
• Structure: monorepo, single package, microservices
• Entry points: main files, CLI entry, API routes
• Key directories: src/, lib/, cmd/, internal/, tests/

3. Codebase Map

Create a mental map of:

• Core modules and their responsibilities
• Data flow (API → Service → Database)
• Configuration files and env vars
• Build/test/deploy pipeline
• Dependencies and their purposes

4. Conventions Detection

Look for:

• Naming: camelCase, snake_case, kebab-case
• Imports: relative, absolute, barrel files
• Error handling: try/catch, error boundaries, custom errors
• Testing: framework, patterns, coverage expectations
• Git: commit message format, branch naming

5. Create CLAUDE.md / AGENTS.md

Structure the file as:

# [Project Name]

[One-paragraph description]

## Quick Start

[How to run the project]

## Architecture

[High-level structure]

## Key Files

[Important files and their roles]

## Conventions

[Code style, naming, patterns]

## Common Tasks

[How to add features, fix bugs, etc.]

## Environment

[Required env vars, config files]

## Testing

[How to run tests, test conventions]

## Deployment

[How to deploy, CI/CD]

6. Validation

After creating the file:

• Verify all referenced paths exist
• Check that commands actually work
• Ensure examples are accurate
• Test any code snippets

Example Usage

User: Please analyze this codebase and create a CLAUDE.md file, which will be given to future instances of Codex working on this codebase.

Agent workflow:
1. ls -la (discover project structure)
2. cat package.json / go.mod (identify language/framework)
3. Find key source files
4. Analyze architecture
5. Create comprehensive CLAUDE.md
6. Validate references

Output Format

The CLAUDE.md should be:

• Concise: 200-500 lines max
• Actionable: Focus on what agents need to know
• Accurate: Only include verified information
• Bilingual: English primary, Chinese comments if helpful

Key Analysis Points

For TypeScript/Node.js Projects

• Check package.json for scripts, dependencies
• Look for tsconfig.json configuration
• Identify build output (dist/, build/)
• Check for monorepo (lerna, nx, turborepo)

For Go Projects

• Check go.mod for module name and dependencies
• Look for cmd/ directory structure
• Identify internal packages
• Check for Makefile or build scripts

For Python Projects

• Check pyproject.toml or setup.py
• Look for requirements.txt or poetry.lock
• Identify package structure
• Check for virtual environments

Don't Use This Skill For

• Modifying code (use other skills)
• Deploying (use deployment workflows)
• PR review (use pr-review skill)
• Issue investigation (use issue-investigation skill)