Reviewing Jev: a decision model that is cheaper, not smarter
TL;DR Jev is TypeSafe AI’s first “System One” model, public since 2026-09-15. You send it a state object and a few typed questions, and it returns probabilities in 70 to 500 ms. I wrote a design doc for using it in my own tooling, and then rewrote it twice in two days because the first draft was wrong in ways I only noticed by rereading the sources. Nothing is built. There is no client, no table, no spike, no measured number of mine in this post. This is a review of a third-party product before I adopt it. Every accuracy and cost figure below belongs to the vendor or to a third party, and I label it that way. ...