codebase-onboarding

# Codebase Onboarding Systematically analyze an unfamiliar codebase and produce a structured onboarding guide. Designed for developers joining a new project or setting up Claude Code in an existing repo for the first time. ## When to Use - First time opening a project with Claude Code - Joining a new team or repository - User asks "help me understand this codebase" - User asks to generate a CLAUDE.md for a project - User says "onboard me" or "walk me through this repo" ## How It Works ### Phase 1: Reconnaissance Gather raw signals about the project without reading every file. Run these checks in parallel: ``` 1. Package manifest detection → package.json, go.mod, Cargo.toml, pyproject.toml, pom.xml, build.gradle, Gemfile, composer.json, mix.exs, pubspec.yaml 2. Framework fingerprinting → next.config.*, nuxt.config.*, angular.json, vite.config.*, django settings, flask app factory, fastapi main, rails config 3. Entry point identification → main.*, index.*, app.*, server.*, cmd/, src/main/ 4. Directory structure snapshot → Top 2 levels of the directory tree, ignoring node_modules, vendor, .git, dist, build, __pycache__, .next 5. Config and tooling detection → .eslintrc*, .prettierrc*, tsconfig.json, Makefile, Dockerfile, docker-compose*, .github/workflows/, .env.example, CI configs 6. Test structure detection → tests/, test/, __tests__/, *_test.go, *.spec.ts, *.test.js, pytest.ini, jest.config.*, vitest.config.* ``` ### Pha...