The most expensive RAG failure is often not an empty search result.

It is a confident answer built on chunks that should never have been retrieved in the first place.

A user asks, “What is my order status?” The system retrieves three generic shipping policy documents, one old FAQ, and a refund guide. The model synthesizes something plausible, cites the wrong policy, and now support has to clean up the mess.

Retrieval worked. The pipeline still failed.

This is the next RAG problem: not just finding relevant documents, but deciding whether retrieval should happen at all.