Published: 2026-09-19
Summary

Jev live: gating a destructive delete at 96% "no", and scoring a sales lead at 97% confidence

Chapters / key moments (click to jump — plays here on the page)

The clearest demonstration we've seen of why a probability beats a sentence for agent decisions. Both demos run in the OpenRouter playground, so you can follow along without an early-access invite. The destructive-delete example is the one to copy: it is exactly the gate an unattended agent needs before it runs a tool call.

Source video

"Jev by TypeSafe AI: System One Model Explained With Live Demos" by AiNow — Watch on YouTube →

Demo 1 — gating a destructive tool call

The state: a task ("clean up inactive accounts before the quarterly report"), a proposed tool call (a delete against the customer table), and context — the table's row count, and that no backup was taken today. The question: is this action safe?, with criteria spelling out that safe means reversible or low impact, and destructive means not reversible.

Jev answered yes at 0.4% and no at 96%, with the recommendation to pause and ask a human. The JSON response carried the conversation id, the model and provider, the answer, the probability, and the input tokens, output tokens and cost.

Why this one matters

The decision turned on a fact in the context — no backup today — not on the wording of the request. A gate is only as good as the state you assemble for it. Build the state deliberately: what the tool would do, what it would touch, and what safety net exists.

Demo 2 — lead qualification

An inbound email: tried the product last month across two teams, engineers want to standardise, the incumbent contract ends on the 30th, asking for enterprise pricing for 40 seats and a security review call. The question was a Score across ordered levels — just browsing, evaluating, ready to buy, urgent with a deadline.

Result: urgent, at 97% confidence, with the probability for every other level returned alongside it. His point, from building enterprise workflows: when software acts on a model's decision, the confidence number is what stakeholders ask for first, and here you get it without asking for it in the prompt.

The comparison with ChatGPT

He pasted the same state and questions into ChatGPT, which answered correctly — the question was easy. The difference was what came back around the answer: no confidence value, no probability distribution, and no guarantee the shape stays the same on the next call. You can prompt a chat model into structured output, but you are maintaining that prompt; Jev is built to return only that shape.

Key Takeaways

You do not need early access to try it: the OpenRouter playground runs the same model, billed per input token.
Ask the safety question with the context that makes it answerable (backup status, row counts, reversibility).
Read the whole probability distribution, not just the winning option — a 97% and a near-tie should route differently.
The response includes token counts and cost per call, which makes per-decision budgeting straightforward.
Not for chatbots: he is explicit that this model is for decisions inside software, not conversation.

Setup, SDKs and the version-pinning gotcha: our Jev setup guide. More places it fits: use cases.