jevchat 🔮

A ChatGPT-style chat UI for Jev, TypeSafe AI's System One model that never generates text — it only decides.

By default Jev answers Yes or No. You can switch to other answer styles (Yes/No/Maybe, Mom, Pirate, Tabloid headlines, …) or create your own custom set of answers for Jev to choose from.

Features

• ChatGPT-like UI: sidebar with chat history, main chat area
• Answer styles built on Jev's calibrated probabilities (noul) and choice questions
• Custom answer styles (stored locally)
• Chat titles extracted from your question by Jev itself (choice over question fragments, segmented with Intl.Segmenter so Japanese works too), with playful fallbacks when Jev isn't confident
• English / Japanese UI, defaulting to the browser's language preference
• History kept in localStorage (max 10 chats — it's a demo)
• Styling: Tailwind CSS + Basecoat UI, dark mode included

Running locally

Requires Deno 2.x and a TypeSafe AI API key.

JEV_KEY=your-api-key deno task start
# → http://localhost:8000

Deploying to Deno Deploy

The entrypoint is main.ts. Set the JEV_KEY environment variable in your Deno Deploy project settings.

deno deploy

How it talks to Jev

The server proxies POST /api/chat to POST https://api.typesafe.ai/v1/systemone (the API key never reaches the browser):

• Every answer style (built-in and custom) sends a choice question whose criteria are the style's answers, so Jev itself picks which answer to give — there is no client-side probability mapping. The collapsed "details" toggle under each reply shows Jev's calibrated probability for every option.
• Remix styles (Daily fortune, Politician, Tabloid) go one step further: the server splits the question into fragments (the same Intl.Segmenter machinery as chat titles), crosses them with verdict templates like "【悲報】{}、ナシ", and Jev picks one fully composed answer — deciding the verdict and which fragment is the topic in a single choice question.
• On the first message of a chat, a second choice question asks Jev to pick the question fragment that best captures the topic, which becomes the chat title.