LLM can be made deterministic too, they’re just generally not because the element of randomness is a feature.

There’s a big difference between deterministic and smooth though. Typical LLMs certainly aren’t reliably smooth, so the small prompt change might product a large and unpredictable output change. I’m not sure if that’s any better with the typesafe approach.

Hallucination is the result of a series of choices of options based on poor predictions of probability (or poor sampling from a probability distribution). As I understand the typesafe approach they’re allowing the set of options to be constrained, but the potential for a misrepresentative probability distribution is still there, and hence so is the potential for “hallucination”.

Yes, but that won't be a hallucination. Same root cause, but IMO it was pretty clear they meant "given options red, green, blue this will never say purple", doesn't mean it still can't misclassify green as blue.