Claude Code Helped Me Understand a Legacy Codebase in One Day

I used Claude Code to onboard to a messy old React/Node repo, and it worked surprisingly well. I asked it: - “Summarize this repo’s architecture” - “How is authentication implemented?” - “Which models are used in this folder?” It gave me useful answers based on code structure and variable/function names. Saved me hours. Bonus: This book helped me refactor what Claude exposed: [Working Effectively with Legacy Code](https://www.amazon.com/dp/0131177052?tag=igorganapolsk-20)