Ask HN: Anyone solved hallucination or semantic drift in RAG?

i’ve worked on a bunch of RAG pipelines recently (pdfs, semantic search, QA bots) — and honestly the biggest failure mode isn’t crash or latency, it’s quiet hallucination.

the model:

    retrieves a chunk that looks right but is semantically off

    loses reasoning chain after 2–3 hops

    confidently gives answers based on mismatched or context-drifting chunks

sometimes you can fix it with chunk overlap or re-ranking, but often it’s deeper: cosine similarity just isn’t enough to preserve semantic continuity.

has anyone here actually solved this in production?

i ended up mapping out 13 of these failure patterns (like drift, loop collapse, overconfidence, broken symbolic prompts), and patched the system structurally — not just prompt tricks.

curious if anyone else has tackled this structurally, or just learned to “live with it”?

(no links / not promoting anything here — just legit wondering if anyone went beyond band-aids)