I Tested 28 Query Pairs to See if Semantic Caches Actually Lie to Users. The Result Surprised Me

I had a clean theory about how RAG caches silently corrupt your answers. Then I built one, ran the numbers, and the actual failure mode was the opposite of what I expected. Let's face it Most of us building RAG pipelines treat the LLM call as atomic. Query comes in, embed, retrieve, generate, return. If we cache anything, we slap a Redis in front of it, key by the query string, call it a day, and move on to the next ticket. Then someone tells you "we should use semantic caching, embeddings will