Earlier quoted context omitted.
In the modes in APIs, the sampling code essentially "rejects and reinference" any token sampled that wouldn't create valid JSON under a grammar created from the schema. Generally, the training is doing 99% of the work, of course, it's just "strict" means "we'll check it's work to the point a GBNF grammar created from the schema will validate." One of the funnier info scandals of 2025 has been that only Claude was eve…
> In the modes in APIs, the sampling code essentially "rejects and reinference" any token sampled that wouldn't create valid JSON under a grammar created from the schema. I thought the APIs in use generally interface with backend systems supporting logit manipulation, so there is no need to reject and reinference anything; its guaranteed right the first time because any token that would be invalid has a 0% chance of…
There is a substantial performance cost to nuking, the open source internals discussion may have glossed over that for clarity (see github.com/llama.cpp/... below). The cost is very high, default in API* is not artificially lower other logits, and only do that if the first inference attempt yields a token invalid in the compiled grammar.
Similarly, I was hoping to be on target w/r/t to what strict mode is in an API, and am sort of describing the "outer loop" of sampling
* blissfully, you do not have to implement it manually anymore - it is a parameter in the sampling params member of the inference params
* "the grammar constraints applied on the full vocabulary can be very taxing. To improve performance, the grammar can be applied only to the sampled token..and nd only if the token doesn't fit the grammar, the grammar constraints are applied to the full vocabulary and the token is resampled." https://github.com/ggml-org/llama.cpp/blob/54a241f505d515d62...