# Making RAG admit when it's guessing: source-grounded hallucination checks

> Source: <https://dev.to/sidswirl/making-rag-admit-when-its-guessing-source-grounded-hallucination-checks-g22>
> Published: 2026-07-01 15:12:48+00:00

The failure mode that scares me most in RAG isn't a wrong answer. It's a confident wrong answer with three citations that don't actually say what the answer claims.

So in SWIRL 5 I stopped trusting the model to police itself and added a check that runs *after* generation.

The flow:

The interesting part wasn't the entailment model; it was everything around it.

**Claim segmentation is harder than it sounds.** Naive sentence splitting produces claims that are unverifiable on their own because the subject lives two sentences up.

**Citations lie by omission.** A model will cite a document that's *topically* relevant but doesn't contain the specific number it just quoted. The whole point of the check is to catch exactly that gap.

**Latency budget.** An honesty layer nobody waits for is an honesty layer nobody ships. SWIRL 5 batches and optionally caches passage embeddings and more.

The result isn't "SWIRL never hallucinates." Nothing can promise that. The result is: when it's on thin ice, it tells you, and it points at the exact sentence.

That's the version of trustworthy I can actually build.