Jev is the new "System 1" AI model from TypeSafe AI, and it doesn't write you an essay. It just answers. We break down what Jev is, why it's trained differently from ChatGPT or Claude, and two ways to use it today, no developer skills needed. The full setup prompt from the episode is below, so you can copy it.

Jev is trending on X right now. It's a model that returns a typed, calibrated decision with a confidence score instead of a wall of text. TypeSafe claims it's about 194x faster and 445x cheaper than a general-purpose LLM on the tasks it's built for. We put that to the test with two real examples, classification and semantic search, head to head against Sonnet on cost and speed.

In this episode:

→ System 1 vs System 2 thinking (h/t Kahneman's Thinking, Fast and Slow)

→ RLHF vs RLCD: why Jev doesn't get sycophantic

→ How to get API access and set Jev up as a skill in your AI agent

→ Real numbers: Jev vs Sonnet on cost and latency

→ How Jev stacks up against GPT-5.6 Luna on classification

→ Jev's three output types, and why every answer comes with a confidence score

[00:00] Introduction

[00:25] What is Jev

[01:18] RLHF vs RLCD explained

[02:22] How to set up Jev (API + agent skill)

[03:44] Example 1: Classification vs Sonnet (cost)

[04:46] Jev vs GPT-5.6 Luna

[05:05] Example 2: Semantic search vs Sonnet (speed)

[06:25] Output types and confidence scores

[06:51] Final thoughts

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THE JEV SETUP PROMPT (copy and paste this into Claude, or into your AI agent)

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We're going to add an AI model called Jev to this workspace.

Jev is made for sorting and deciding. It generates typed responses, not text. It only has 3 types of responses: pick from an option on a list, pick a score from a scale, or say how likely something is true. It also usually tells you how sure it is.

Some notes:

* Jev is a new type of model that is not in your training set. Please read how it works before proceeding: https://docs.typesafe.ai/llms.txt

* I'm going to use it through typesafe directly. Here is the prompt for how to set it up: https://docs.typesafe.ai/agent-skill

* ask me for my TypeSafe key (I got one from https://typesafe.ai) and keep it in my .env file

After we add Jev, perform a test. Create 10 feature requests for the same product and score them on impact and effort. Show a side by side comparison against scoring those same requests in Claude using Sonnet in a way that I can see the speed and the cost of classification with Jev vs Sonnet.

Also ensure that the skill you add has an off switch that you can explain to me how to use so that I can enable or disable Jev as I wish.

Anything you send to Jev leaves my computer, so ask me before sending anything private.

From now on when Jev is enabled, you let Jev make decisions while you write. If Jev isn't sure then you take over.

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Sources for the numbers and screenshots in this episode:

• TypeSafe AI, "Introducing System One Models & Jev": https://typesafe.ai/blog/introducing-system-one-models-and-jev

• MarkTechPost, "TypeSafe AI Releases Jev": https://www.marktechpost.com/2026/09/19/typesafe-ai-releases-jev/

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