Jev in discussion
Two places did to Jev what they do to anything that changes how software is put together: argued about it in public, then rebuilt it in public a few times over. Hacker News ran the launch threads; dev.to is where the people who actually integrated it wrote up what happened, including the two independent benchmarks below. Ordered by the platform's own number — points on Hacker News, reactions on dev.to — and labelled so you can tell which.
Points, reactions and comment counts read 2026-09-23 · 11 kept an earlier reading 14 threads published
- Hacker News
Hacker News
Introducing System One Models and Jev
The launch thread, and the largest single discussion of this model we can count. Start here for volume and for the objections raised in week one; the vendor's own announcement is in the resources column.
- Hacker News
Hacker News
Kev: Tiny Jev-like family of decision models built on top of Qwen3.5
A third-party rebuild of the same idea on Qwen3.5 instead of a call to the hosted model. The clearest evidence that what people are copying is the decide-act loop, not the endpoint.
- Hacker News
Hacker News
Jev-Leftpad
The joke build: the decision pattern wrapped around a trivial utility. Worth reading as a size reference for how little code the smallest useful instance needs.
- Hacker News
Hacker News
I turned Jev into a (lousy) chatbot
Someone aimed a decision model at a job that belongs to a language model and said so in the title. The thread is the argument about where that line actually falls.
- Hacker News
Hacker News
Reverse-engineered Jev-like model
An independent reconstruction of the architecture. Read it next to the vendor's quickstart, because the two disagree in places worth knowing about.
- Hacker News
Hacker News
Open-sourced jev architecture last year with model,paper and dataset
A prior publication arguing the pattern predates this release, with the paper and dataset linked in the thread. Useful as the before-picture when the naming conversation comes up.
- Hacker News
Hacker News
Jev Ultrafast: A browser agent with a dynamic, indexed action space
A browser agent driving an indexed action space. We read this repository line by line for the resources column; the thread is where its author answers questions about it.
- Hacker News
Hacker News
Show HN: CUA-S1 – A System One Model for Computer Use
A separate System One model, aimed at computer use rather than typed decisions. The clearest sign that the name is turning into a category rather than a product.
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Hacker News
Show HN: jevals – replacing LLM judges with typed Jev decisions
Replaces the LLM judge with a typed decision, which is the use case we expected to appear first and the one with the clearest failure mode. The thread's own objection is the one to keep: what happens when the judgement depends on context the typed decision cannot carry.
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Hacker News
Show HN: Jeff – A read-only CLI for semantic code review using Jev
A read-only review CLI, and the thread argues about the word read-only rather than the model: one commenter points out that in a coding agent an edit is refused unless the file was already read in that conversation. Good thread for the enforcement question.
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Hacker News
Jev, Prolog, Pi, and the dream of probabilistic logic programming
No comments yet, which is itself the interesting part: an essay putting Jev next to Prolog and probabilistic logic programming — the argument that a decision is a query, not a completion. Read it for where the idea came from.
- dev.to
dev.to · 10 min read · AI-assisted
LLMs Generate. Jev Decides. Software Should Know the Difference
An integration write-up rather than a benchmark, and the framing is the reason it is here: the author's complaint is that we took a machine built to generate open-ended sequences and asked it politely not to be. He put Jev into a real Java invoice-processing application through The Pipeline Framework, found the old prompt already contained the list of answers, and reports that some of the work being sent to an LLM was never an LLM problem. Declared AI-assisted on dev.to.
- dev.to
dev.to · 6 min read
TypeSafe’s JEV Model: Is It Really 193x Faster and 444x Cheaper?
The independent check on the two numbers everyone quotes. They ran 100 support tickets through four question types against three frontier models — 400 decisions each — and measured 4x to 7x faster and 31x to 65x cheaper, not the 193x and 444x on the launch page. Their explanation is the useful part: a multiple is a property of the comparison, and the vendor compared against slow multi-step workflows while they compared against mid-tier single calls. They also reproduce the vendor's own side, a 474 ms median against the published 70-500 ms.
- dev.to
dev.to · 8 min read
Benchmarking Jev: what a decision model can (and can't) do in an agent harness
The most useful dev.to piece on this model so far: about 22,500 calls across ten public datasets, with the code and raw results in a companion repository. Half the value is the negative results — model-difficulty routing at 51% (no signal at all), trajectory failure attribution at 0.560 AUROC (random), and non-English retrieval well below English. The other half is two engineering lessons from iterating: decompose a fuzzy judgment into orthogonal questions and compose them in code, and let a choice compete before a noul verifies.
What this column does not have
What this column covers, and what is still missing
Two sources: Hacker News, read through the Algolia API, and dev.to, read through its public API. Both were re-checked on 2026-09-23, because this column started as Hacker News only and the reference implementation we mapped it onto carries two sources:
- Reddit — the public JSON returns 403 without OAuth, and creating the app is still blocked; that is a dead end we have already written down once.
- Bluesky —
public.api.bsky.appanswers 403 to an unauthenticated search. - Lobsters — 400, "unpermitted query or form parameter".
- dev.to — 200, and now in. Its API is open and it already had thirty Jev posts, including two independent benchmarks.
Which is why the page is called "Jev in discussion" and not "Jev on Hacker News": it stopped being one forum today. The URL never said Hacker News, so nothing has to move for a source to be added — that was the point of naming the column after the shape rather than the site. What a reader should watch for is that the two platforms measure different things: Hacker News counts points, dev.to counts reactions, and a wall that printed both as "score" would be quietly lying about one of them. Each card says which number it is showing.
Videos. They are a separate column, because a thread is something you read and a video is something you watch — an index that mixes them makes you open both to find out which you got. The demonstrations and walkthroughs people recorded are collected under videos, and the things that came out of these threads with a repository attached are under what people built.
We also do not paste the comments. A thread is a conversation with its own permalinks, and a copy of it here would be both worse to read and out of date within a day — what we keep is the count, the date and our own reading, and the link goes to the thread itself.
Source: Hacker News via the Algolia API Every item linked, no content copied Jev topic