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The System One Decision Model

The System One Decision Model

TypeSafe Jev is an AI model that makes decisions for software: it answers questions you define about text or JSON and returns each answer with a probability.

The System One Decision Model cover

Overview

Jev AI: The AI Model That Makes Decisions, Not Text

Jev AI — The System One Decision Model by TypeSafe AI

Jev AI is a "System One" decision model developed by TypeSafe AI. It does not generate natural language. Instead, it takes a state and a set of predefined questions, then returns typed answers with confidence scores.

Core Capabilities

Question Type	Purpose	Output
`Choice`	Select from predefined options	Option + confidence
`Score`	Rate on a custom scale	Score + confidence
`Noul`	Yes/no or probabilistic judgment	Probability between 0 and 1

Key Figures

Latency: ~70–500 ms end-to-end
Speed: Up to 193.6× faster than frontier large models in specific benchmarks
Cost: Input at $0.042 per million tokens, output free
Cost efficiency: Officially claimed to be 444.6× cheaper than comparable large models
Release: Launched September 15, 2026; opened to all developers September 20, 2026, with no waitlist

Typical Use Cases

Ticket routing, risk scoring, tool selection, email classification, log judgment, and other automation tasks that require semantic understanding but no text generation.

Where to Try It

Official Playground: console.typesafe.ai
OpenRouter: model ID typesafe/jev-1.13 or ~typesafe/jev-latest
Vercel AI Gateway / LiteLLM: can be integrated as a backend model

Design philosophy: Decisions, not strings.
Inspired by Daniel Kahneman's "System 1" fast, intuitive judgment and the Jevons paradox.

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