alt Hacker NewsIf you really know what grammers did, grammer is a filter to mask out option llm provided but you don't like.
It does not change potential distribution in any means. It DROPS part of answer model returned directly.
The text generation model go wild because model relies on previous section it answered to continue later section. And because now it contain item model have no idea, it is completely screwed.
In the case you only require model to answer one of a,b,c,d and don't care about later segment at all. It don't really matter.
What I mean is that, in general, constrained decoding can push model output off into less probable regimes. This is well studied; see for example https://arxiv.org/pdf/2606.21619. The mask may only retain very improbable logits. In pathological cases, the constrained output may be little better than noise filtered through the constraint. When using existing structured output APIs, it may not be possible to even know.