Using Claude Code on a codebase you just joined

Claude is useful when you are new to a codebase. It can explain what code does, trace data flows, and answer questions about how things connect. But it can also write changes that break implicit conventions you do not know about yet. Use Claude to read, not write, for the first week Before you understand the codebase, use Claude as a reader and explainer. 'What does this function do?' 'Where does this data come from?' 'Why might this be structured this way?' These are safe — Claude is not changing anything, and the answers help you build a mental model faster. Asking Claude to make changes before you understand the patterns means it might follow patterns that do not match the team's conventions. The architecture question Early on, give Claude the relevant part of the codebase and ask: 'Describe how this system is organized. What are the main modules, what are their responsibilities, and how do they communicate?' Claude's answer will not be perfect, but it gives you a starting model to