Iron Law: Read actual files before making any claims about the codebase. Never infer stack from directory names alone — read the config files. A wrong CLAUDE.md is worse than no CLAUDE.md.

Codebase Onboarding Skill

Systematically maps an unfamiliar codebase in 4 phases, then generates two artifacts: a structured Onboarding Guide and a tailored CLAUDE.md.

When to Use

• Opening a new client project with Claude Code for the first time
• Joining a new team repository
• User asks "onboard me", "analyze this codebase", "generate a CLAUDE.md"
• Updating an existing CLAUDE.md to reflect current project state

Four-Phase Analysis Workflow

Phase 1: Reconnaissance (read config files, not source)

Gather signals without reading all source files. Run these in sequence: