Decision AI models gain momentum: TypeSafe jev leads the charge against Fastino and open-source rivals

Decision AI models, which return structured decisions rather than text, have gained traction with the launch of TypeSafe AI's Jev. Introduced after two years in stealth, Jev is marketed as a 'System One model,' inspired by Daniel Kahneman's fast thinking. Within three weeks, Fastino Labs and open-source developers released competing models. Jev processes questions in parallel, offering fast responses and avoiding type errors. It uses Reinforcement Learning for Calibrated Decisions (RLCD) and costs $0.042 per million input tokens. Jev outperformed Sonnet 5 in accuracy but lagged behind top models by 6.3 points. Vercel reports Jev became the fastest-adopted model in AI Gateway history, with 13% of paid teams using it within 24 hours. Fastino's GLiDE and GLiNER2.5-Decide models use different testing and comparison methods, including JevK5, an open-source reproduction. While decision models are not new, the 2026 shift in packaging, driven by four forces, has accelerated their adoption.