Having worked on calibration in our RLCR paper, here are some thoughts on decision models :
1. Distinction between a decision model and a classifier
imo, decision models are a subset of classifiers, with the added flexibility of defining the output space at inference time. Every decision model is a classifier, but not every classifier is a decision model.
2. Training a decision model
The approach that comes to mind is to replace the LM head with a fixed size classifier head (seems to be 256 for Jev) and fine-tune using data mapped to a structured classification format.
If this is the case, I don't see why frontier models fine-tuned to be "decision models" wouldn't just win at this task. They already have the strongest representational backbones, and with some fine-tuning, they'd probably make the strongest decision models too.
I think decision models are a clever and useful idea, and there's clearly a market for them. But I don't see an obvious secret sauce that would prevent frontier models (or their smaller counterparts, if efficiency is the differentiating factor) from winning.