They explicitly are only doing lexical matching. I actually don’t mind this if it lowers the cost; LLMs can turn lexical search into a very powerful tool by iterating on the queries. Just look at the success of coding agents using grep and similar code search tools.
yeah, but the bigger the corpus the more you are relying on the LLM guessing the right keyword, if there is no reranking in place, you will just end up burning through a lot of tokens.
coding agents is a very "niche" use-case where lexical matching works very well. code is a graph, by looking at few lines of code you can guess naming conventions etc. codebases are small compared to knowledge bases.
the bigger your index, the more you will need way better tools such as search.
But it does seem like their index isn’t great.