Claude Code Large Codebase Best Practices: Mastering AI Navigation in Million-Line Repos

How to Use Claude Code in Large Codebases: Best Practices from Real Deployments Claude Code is already running in production environments that include multi‑million‑line monorepos, legacy systems built over decades, distributed architectures with dozens of separate repositories, and organizations with thousands of developers. These environments create challenges that small, simple codebases simply don’t have – for example, build commands that differ from one subdirectory to the next, or legacy code scattered across folders without a shared root. This article summarises the patterns we have seen lead to successful adoption of Claude Code at scale. When we say “large codebase”, we …