# John Berryman — OpenAI could copy Jev, so TypeSafe's moat is its data

> Jev runs on standard transformer machinery, so John Berryman expects OpenAI to build its own version before long.

- Org: Arcturus Labs
- Date: 2026-09-21
- Category: article
- Source: https://arcturus-labs.com/blog/2026/09/21/will-openai-eat-jevs-lunch/
- Canonical page: https://ai-tldr.dev/releases/arcturus-openai-fast-follow-jev/

## In short

John Berryman argues OpenAI could add Jev-style typed decisions to its own models quickly, because Jev runs on ordinary language-model machinery. He says TypeSafe's real advantage is its training data, not its architecture.

## What it is

OpenAI is well placed to copy Jev, argues John Berryman, founder of Arcturus Labs and a co-author of 'Prompt Engineering for LLMs'. Jev, from TypeSafe, returns a calibrated typed decision instead of generated text; Berryman's reading is that it gets there with conventional language-model machinery rather than a new architecture.

## How it works

The argument turns on where the value actually sits. A language model already produces a probability distribution over tokens, and Berryman notes OpenAI has effectively been doing classification for years through tool calling. He sketches a path where OpenAI embeds classification inside its own models behind special syntax tags, letting a model make a calibrated judgement — for a safety check, a tool validation, or routing to another model — without leaving the GPU.

## Why it matters

If the mechanism copies easily, TypeSafe's future rests on its data. Berryman quotes a TypeSafe cofounder saying 'we consider ourselves a data research lab' and that 'the vast vast vast majority of research was on making data that is truly general'. His conclusion is binary: a deep moat makes TypeSafe an acquisition target, and a shallow one means 'OpenAI just builds it themselves, and TypeSafe's window closes fast.'

## Who it's for

developers weighing Jev and other typed-decision models

## Links

- [Original Post](https://arcturus-labs.com/blog/2026/09/21/will-openai-eat-jevs-lunch/)
- [HN Discussion](https://news.ycombinator.com/item?id=49802161)
- [Jev Announcement](https://typesafe.ai/blog/introducing-system-one-models-and-jev)