Don’t Average the Needle: Spectral Retrieval and the RAG Evidence Problem
Enterprise search has a very old habit wearing a very modern jacket: it averages. A policy document becomes one vector. A runbook becomes one vector. A postmortem full of operational detail becomes one vector. Then a RAG system asks that one vector whether the document is relevant. This is convenient, fast, and usually defensible — until the relevant answer is a narrow paragraph hiding inside a large document. At that point, the retrieval system is no longer searching for evidence. It is asking a crowd to speak for the witness. ...