Comment by postalcoder 12 hours ago
This doesn't fully satisfy your question, but it comes straight from bcherny (claude code dev):
> Claude Code doesn't use RAG currently. In our testing we found that agentic search out-performed RAG for the kinds of things people use Code for.
source thread: https://news.ycombinator.com/item?id=43163011#43164253
They are using RAG. Grep is also just RAG. The better question is why they don’t use a vector database and honestly the answer is that these things are incredibly hard to keep in sync. And if they are not perfectly in sync, the utility drops quickly.
I forgot to mention that Aider uses a tree sitter approach. It's blazing fast and great for quick changes. It's not the greatest agent for doing heavy edits but I don't it has to do with them not using grep.
Thanks, I was also wondering why they don't use RAG.