What Is Jev? A Beginner’s Guide to TypeSafe AI’s Decision Model

Jev is an AI model from TypeSafe AI that makes structured decisions instead of writing chat replies. Give it a message and a few focused questions, and it can choose a category, rate urgency, or estimate whether the sender asked for a person.

In this guide, you’ll use Jev to sort incoming requests. Start in the browser with made-up messages, then use the optional coding-agent prompt to turn the demo into a small app.

TypeSafe introduced Jev on September 15, 2026. It calls Jev a System One model: a model built for fast, focused judgments that software can use directly.

For example, instead of asking an AI to write a reply to a customer, you could ask Jev:

Is this an access problem or a billing question? How urgent is it? Did the sender ask to speak to a person?

Your app can use those answers to suggest a support queue or flag a message for review. Jev supplies the judgment; your software controls the next step.

Jev is not a chatbot or a coding assistant. It does not write emails, generate code, or replace the model inside Claude Code. You can use a coding agent to build an app that calls Jev.

This walkthrough suits operations teams sorting incoming requests, founders building small internal tools, and anyone who wants to try a decision model without first learning an API.

A request sorter that answers three questions about one message:

These are Jev’s three question types. Choice selects from your options, Score rates against levels you define, and Noul returns the estimated probability of “yes.”

The demo will not send messages, change accounts, or issue refunds.

Use the official TypeSafe Playground, a TypeSafe account, and a few sample messages. TypeSafe’s quick start supports trying text and questions in the Playground before writing code.

Use invented or redacted messages for your first test. Keep customer details and private company data out until your team has approved the tool.

TypeSafe provides a skill that helps coding agents work with Jev’s API. Review the skill before installing it. For Claude Code, the official installation commands are:

claude plugin marketplace add typesafe-ai/skills
claude plugin install typesafe@typesafe-ai

Create an API key in the TypeSafe console. Store it as the server-side environment variable TYPESAFE_API_KEY; keep it out of browser code, shared prompts, screenshots, and source control.

Then give your coding agent this prompt, along with the starter request JSON:

Use the TypeSafe skill to build a local app called Request Sorter.

The user pastes one message and clicks Analyze. Call Jev on the server
using the questions in jev_starter_request.json. Return the topic,
urgency score, human-request probability, and available confidence values.
Show the original message beside the result.

Read TYPESAFE_API_KEY from a server-side environment variable. Never
expose it to the browser or log it. Do not store messages by default.
Use the official SDK and pin model jev-1.13.0 for this demo.

Keep the questions and review threshold in one editable file. Mark the
result for review when the topic is other or its confidence is below 0.8.
Keep explicit requests for a person visible. Explain that this threshold
is provisional, not a guarantee of accuracy.

Add loading, error, timeout, and rate-limit handling. Make no API call
until Analyze is clicked. Do not connect email, send replies, issue
refunds, or change accounts.

Add synthetic test inputs and setup instructions. Clearly distinguish
mock tests from live Jev calls. Never display mock output as a live result.

Your coding agent writes the app. Jev evaluates the messages inside it. Those are separate jobs.

As of September 22, 2026, TypeSafe lists Jev 1.13 at $0.042 per million input tokens, with no charge for output tokens. Input usage includes the material and questions you send.

For scale, 10,000 calls averaging 1,000 billed input tokens each would cost about $0.42 in model input fees. That is an estimate, not a measured cost for this demo, and it excludes app hosting or other services.

Check current pricing and any account credits before running a large batch.