Claude Code Doesn't Index Your Codebase. Here's What It Does Instead.
Last verified: March 2026
Boris Cherny's team built RAG into early Claude Code. They tested it against agentic search. Agentic search won — not narrowly. A Claude engineer confirmed it in a Hacker News thread: "In our testing we found that agentic search outperformed [it] by a lot, and this was surprising."
That thread is the clearest primary source on how Claude Code actually works — and why it works that way. Most articles on the topic paraphrase it from memory. This one starts from the source.
Q: Does Claude Code index your codebase? A: No. Claude Code does not pre-index your codebase or use vector embeddings. Instead, it uses filesystem tools — Glob for file pattern matching, Grep for content search, and Read for loading specific files — to explore code on demand as it works through each task. Anthropic calls this "agentic search."