Projects, posts and guides about Jev, the System One model from TypeSafe AI. Each entry links to its source and shows the cost and speed its author reported.
After co-inventing ChatGPT, I kept asking myself: why have superhuman chat models not led to AGI?
I’ve spent the last 2 years in stealth building a new way to train models (RLCD), and a new type of frontier AI model that we are releasing today: Jev
• 20-200x faster
• 40-400x cheaper (w/ output tokens free)
• Frontier composable intelligence optimized for decisions
AFAICT the shortest path to AI-based economic revolution
Open weights that answer typed questions in one forward pass, 33 ms on a T4.
NMNandakishor M
13.7k
MD Fazal Mustafa
@the_mdfazal
🚨 A LOCAL 421M MODEL JUST ATE CLOUD JEV ON SPEED
Laya is an open-source System 1 decision model that runs on your machine.
Laya: 86.5 decisions/sec, P50 ~9ms, score 46
Jev: 3.2 decisions/sec, 317ms API round-trip, score 1
Ships with:
— 421M params
— ~1GB inference memory
— Millisecond local calls, no network
— Typed decisions in one forward pass
— Apache-2.0 and self-hosted
While the cloud waits, local decides.
Zubair Trabzada's AI Workshop: what Jev actually does, and why calling it an LLM misleads.
Baris Terzioglu
@terzioglubrs
Agent memory is usually just an append-only Markdown file that grows forever, and most frameworks load the whole thing into context on every single run. That has been bothering me for a while, but never quite enough to fix it for our agents. Jev feels like it might be a low effort patch to this, by simply scoring each memory against the prompt first, then load only the relevant bits for that specific request.
Yes but not with Jev. I used another classifier, locally, just as fast, just as good.
Example: setup a "server" in python that loads the classifier model. Add a hook in Claude that fires on "pre-tool-use" and next time you ask Claude a random question like "how do I lint check a project?" and it tries to freelance and read your entire repo only to intoxicate itself and pollute its context, the classifier will slap its hand, say "no sir, you answer from knowledge" and deny the tool call.
I tested this yesterday with success, but need to refine it as it misfires.
Basically I was able to identify general queries, instances where I would ask something and Claude would rush ahead and run pip install without me asking or just write code instead of answering.
A classifier is hypercheap compared to a regular LLM and would catch all of these.
The model I used was DeBERT large. It's still stupid fast, I tested it on an Apple with M1 (regular) and you don't feel it running.
Supabase, in a short: Jev introduced in under a minute.
tanav
@tanavtwt
Created a slop detector extension with Jev
It scans all the post on the screen in the real time and classifies it on categories like scam, slop, clean, etc. Shows a minimal badge on the post with the confidence score.
Comment bellow if you want to try the extension.
Jev is live in New API now!
Choice. Score. Noul.
Structured judgments that drop straight into code.
Same TypeSafe SDK. Point it at your New API gateway.
One plugin. No rewrite.
newapi.pro/zh/plugins
Sam Witteveen goes through the open decision models released in Jev's first week.
Manoj Rajendiran
@svencreations
Creators saying their new tool “killed” another is understandable. It’s marketing and rage bait.
But people retweeting it without even trying the tool? That’s the worrying part.
I’ve seen at least 10–20 “Jev killers”(@typesafeai) on my timeline already. Tried a few myself. Most weren’t even close.
We’re amplifying opinions before forming our own.
I keep seeing the same fix across agent stacks this week: teams are ripping the expensive model out of the middle of their decision loops.
TypeSafe shipped Jev in early access on September 15. Not a chat model. They call it a System One model: hand it a state and typed options, it returns calibrated probabilities, no text generation at all.
The mechanism is simple. Most agent loops burn a full LLM call on decisions that never needed generation: route to worker A or B, is this result relevant, approve or block this action. TypeSafe claims up to 200x faster inference and 400x lower cost on that class of decision. Ricker's own tests below land at 193x and 444x.
What happened next is the real story. Within four days, Cognition's Jared Palmer shipped Kev, a LoRA adapter on Qwen2.5-0.5B trained in 1 hour 45 minutes on a MacBook Pro, with an API close enough to point TypeSafe's own SDK at it. Kev now scales up to a 9B version that trails Jev by about 4.5 points on held out evaluation. Laya-MLX arrived the same week targeting millisecond decisions on Apple Silicon. A community leaderboard, JevBench, already ranks a dozen of these models.
The adoption signal convinces me this is not a toy. TanStack AI shipped a native decide() API for typed choices, scores and booleans. Beacon, an open source memory layer, uses Jev to score which coding sessions are worth turning into reusable lessons. Three teams, one primitive, inside a week.
RouteLLM out of Berkeley showed back in 2024 that routing simple queries to a cheap model cuts cost over 85% while holding 95% of GPT4 quality, and production semantic routers report 40 to 90% savings today. What changed is that the router stopped being a side project and became a shipped, benchmarked model category with a name.
The bottleneck this solves is real: every agent framework has a model sitting in a loop answering questions that never needed a sentence back. My read is that the decision layer becomes as standard a piece of the agent stack as the vector database became for retrieval, and whoever owns the default there owns a lot of the unit economics conversation for the next year of agent infrastructure.
https://x.com/0xRicker/status/2101705843200721203
Prompt Engineering puts Jev in the reranking step of a RAG pipeline: why vector search and cosine similarity fail, how a steerable reranker works, and how it compares with LLM rerankers and cross-encoders. A Colab notebook comes with it.
Stas Kulesh
@staskulesh
Added shareable game result to jevchess.com
Jev won again, but. The robots are coming.
1,000 AI papers sorted into 24 topics for $0.0585. Then Opus 5 graded the labels.
@nutlope's Jev paper map went viral, but the pipeline never shipped and the eval was "still running". So I rebuilt both and opened them.
The first judge run came back empty: Opus spent its whole budget thinking and answered nothing. Reasoning off, second run: it agreed with Jev on 85 of 100 papers, at 153x the cost and 1.9s against 57ms per paper.
The 15 misses are not random. One number Jev already returns tells you which labels to recheck.
Cheap models sort. Expensive models audit only what the cheap one flags.
Repost if you classify anything at scale, because the eval rows are public and anyone can rerun them with their own judge in one command.
Code in the reply.
Julian Goldie’s hour-long course: the three question types, many decisions batched in one request, and ten use cases, from email sorting and lead scoring to internal linking across 586 pages and a browser agent finding flights.
Satoshi Nagayasu 🧠🤖
@snaga
TypeSafe System One(Jev)によるHacker Newsパーソナライズ推薦の実験と複合判定アーキテクチャ
gist.github.com/snaga/12c62ad5…
毎朝、Hacker NewsのチェックをAIエージェントでやってるんだけど、自分向けのレコメンドをJevで組んでみた。
なるほどー、という感じである。楽にはなりそう。
🔥 looks like Jev just got an open-source alternative.
Laya is a 421M parameter model built for making decisions instead of generating text.
the interesting part:
- runs locally on your laptop or phone
- uses less than 1GB of memory
- supports structured decisions (yes/no, scoring, multiple choice)
- free + open source
in a 30-second Snake benchmark against cloud-based Jev:
Laya: 86.5 decisions/sec, score 46
Jev: 3.2 decisions/sec, score 1
the catch? Laya has a 512–1024 token context window and doesn't generalize as well as Jev without additional tuning.
so we already have an open source alternative to jev... and it's 6-7x faster?!
it's a typed-decision classification system: no chat, no generated text, just fast yes/no, scoring, or choice answers.
> runs in under 1gb of memory
> free on hugging face
> runs on a laptop, or even a phone
there's a real demo where it plays snake live, making a fresh decision every single move.
two honest limits, straight from the project itself:
> only 512-1,024 token context, some cases won't fit
> weaker generalization than jev out of the box
Kev makes Jev the decision maker inside HyperEdit, his open-source AI video editor, and walks through the whole setup with Claude Code. The repository is free on GitHub.
Akash Jain
@akashpurjalkar
Jev is playing Minecraft.
I built a bot powered by Jev that can construct houses, towers, lakes and castles on command.
It also fights mobs, uses a sword, and tries to dodge skeleton arrows in real time.
Still rough, but genuinely fun to watch.
@typesafeai Jev
Coderone on Laya, the open System One model from Convai Innovations: what typed decisions are, why they replace a share of LLM calls, and Laya run locally to see if its figures hold up.
Coach Shweta Bajaj
@shwetabjaj
This Jev experiment is fun, but the reliability question is actually the interesting part.
Snake is simple enough to understand, but unforgiving enough to expose bad decisions fast.
Play alone, play with Jev, veto its moves, or race it.
A playful way to test decision quality, corner after corner. 🐍
@typesafeai @CarolMonroe
http://jevplayssnake.lovable.app
Jev Skill Suggestion for Claude Code is a smart idea.
Instead of loading every skill into context, Jev decides which one is actually relevant and injects only that.
My takeaway: better context hygiene, less clutter, and potentially more efficient agent workflows.
@typesafeai @vercel
Jev doesn't write. It only decides.
Yes/no, choices, scores — each with calibrated confidence in 70–500ms.
Input is $0.042 per million tokens. Output is free.
The first System One model. This is the plumbing agents were missing.
firecrawl.dev/blog/what-is-j…
Dave Ebbelaar in Python: a support-ticket classification first, then Choice, Score and Noul, several questions in one call, and latency and price next to Claude Haiku, Opus 5 and Fable 5.1.
Shengkun Ye
@shengkunye
Introducing Jev + OpenRouter + tools.
You can now use Jev with 2,000 tools on Monid. Your agent picks the tools, Jev speeds the work up 30x.
> Score 2,000 leads
> Scan the TikTok viral video hooks
> Research fundraising of 200 companies
> Audit a site's SEO and rebuild the internal links on every page
> Sort every Reddit thread about your category
For marketing $SCRAPS, I’m trying something I haven’t seen anyone else do.
I’ve been experimenting heavily with the latest AI tools (JEV from @typesafeai), burning through 178M+ tokens and nearly 48,000 requests testing different ideas.
One of those experiments is focused entirely on marketing: finding the fastest path to high engagement and the best ROI possible.
Now that SCRAPS is live on Google Play, it’s time to put it to the test.
The experiment starts now.
Raúl Marín, in Spanish: what Jev decides against what an LLM writes, then closed judgments applied to a design system — variant choice, email classification next to GPT, fast UI rendering and screens generated from prompts. 21 minutes, with chapters.
AMIT RAWAT
@sahajamit
I built a Chrome extension that judges every post in my feed before I reach it. READ, MAYBE or SKIP, in about 300 ms, using Jev by @typesafeai. No scripted rules, no selectors, no LLM. Real time, my X feed:
Jev CEO, Diogo Almeida (ex-OpenAI):
"It's not Claude Code because Claude Code is still part of the assistance era."
He co-authored GPT-4, ChatGPT, InstructGPT and RLHF.
Now he's building what comes next:
200x faster. 400x cheaper. A decision brain for AI agents.
His argument is simple: frontier LLMs are insanely good at creating, but we're wasting them on thousands of tiny decisions:
Which agent goes next? Is this relevant? Does this need approval?
Those calls don't need generation. They need a model built to decide.
In 18 minutes, Almeida explains why today's AI was built for assistance, not real automation, and why "tomorrow's AI will be for automation."
This makes most $500 agent engineering courses look obsolete.
Watch it today, then steal my 10-step guide to giving your agents a decision brain below ↓
Jev hype is not about chat.
it’s about decisions
everyone is trying to compare it to ChatGPT / Claude / Cursor
wrong frame
Jev doesn’t need to write you a beautiful paragraph
it needs to answer questions like:
should this agent act now?
which tool should run next?
is this signal worth trading?
is this market mispriced?
should this wallet be ignored or watched?
that is the interesting part
prediction markets are basically endless small decisions under uncertainty
not one giant “AI intelligence” moment
thousands of tiny calls:
price changed
liquidity moved
wallet entered
news dropped
odds lagged
edge appeared
edge disappeared
you don’t want a slow model writing essays for that
you want something cheap, fast, typed, and measurable
that’s why Jev is interesting.
not because it replaces frontier models
because it makes the boring decision layer cheap enough to run everywhere
Akshay Pachaar’s worked example: evaluate a refund-support agent with Jev instead of a generative judge, and record the verdicts in Opik. Separates the judge from the evaluation system, and is explicit that a 0.98 is a probability about one proposition, not a percentage of the answer.
I'm reading up on Jev (typesafe.ai/blog/introduci…) and learning how it differs from "regular" classification ML models.
I gave a bunch of articles to @googlecloud Gemini Enterprise and asked it for a breakdown. Helpful. Still digging in before going hands-on.
all things Jev in one place
a GitHub collection just dropped packed with hundreds of tools, libraries, and projects built on top of Jev, from teams treating decision-making as its own primitive, separate from language generation entirely.
github.com/AnotiaWang/awe…
Comet’s open-source evaluation and tracing platform, Apache-2.0. Datasets, experiments and trace-level feedback, with a custom-metric interface that takes several named scores from one call — which is how a Jev judge is wired into it.
Robotics Alpha
@robotics_alphax
Strike Robot wiring Jev into its Physical AI stack is not a model announcement or a new UI layer. it is an autonomy architecture shift.
the signal that usually separates real autonomy from scripted behavior is where the decision loop lives. when a robot queries a remote model for every action, the latency budget is visible in the motion. there is a pause between stimulus and response that teleoperation hides but autonomous operation cannot. what you want is local inference for routine actions and remote calls only when confidence drops.
staging tells are easy to spot if you know what to look for. when Jev is actually routing decisions, the robot will execute most movements without a cloud round trip. the moment to watch is at decision boundaries. an unexpected obstacle, a grip that slips, a path that changes mid stride. if the system freezes or the motion cadence stutters, the model just got called. if it flows, Jev stayed local and the confidence threshold was high enough. latency in continuous runs is the honest signal.
the gap this closes is always-on large-model inference burning compute on decisions that a smaller local model handles with 95% confidence. a credible in-the-wild demo would show the robot moving fluidly through a routine task, hitting an edge case, pausing once while Jev fires, then resuming without a second stall.
Nitpicky, an AI generated photo detector powered by jev
AI generated photos can be told from nits. That's why we build something to zoom into every detail:
faces, fingers, characters, numbers, poses, where common senses fall apart, judged by jev
Our explainer in Spanish, on LinkedIn: what a System One model is, what Jev decides, and where it fits.
RazeDen
@razeden0
i just merge Grok 4.7 + Jev and got the smartest thing i've ever owned
grok 4.7 does the thinking. jev does the deciding. together they cost less than my coffee
prompt → grok bot → jev asks 6 questions → grok 4.7 opens only the good ones → campaign
jev doesn't write anything. it only answers simple questions: yes or no, pick one, or a score. it can't make things up, because it can only pick from answers you allowed
i gave it 3,412 leads from x, linkedin and youtube. 6 questions each is 20,472 decisions, done in 15.7 seconds for $0.41
the same reading by hand took me 6h 12m. people say 400x faster. i did the math and it's 1,421x
that's $0.00012 per lead, and grok 4.7 only reads the ones worth reading
the big mistake: sending everything straight to the new model. you pay the smartest thing you own to say "skip" all day
setup took me 9 minutes: key in the secure field, sdk on the agent computer, one router skill, test mode first
jev decides, grok bot does the work, and i still press the button on anything i can't undo
everyone is talking about the new model. the cheap one deciding what it reads is where the money is
𝐖𝐡𝐞𝐫𝐞 𝐉𝐞𝐯 𝐁𝐞𝐥𝐨𝐧𝐠𝐬 𝐢𝐧 𝐚𝐧 𝐀𝐠𝐞𝐧𝐭 𝐇𝐚𝐫𝐧𝐞𝐬𝐬 (𝐍𝐨𝐭 𝐚 𝐌𝐨𝐝𝐞𝐥 𝐒𝐰𝐚𝐩)
Your agent harness needs a decision model. Where you place it depends on one brutal fact: Jev's ordering is trustworthy. Its confidence numbers are not.
Most placement guides skip this distinction entirely. They tell you to pick a threshold and execute above it. That works if you actually have a probability. You might not.
𝐓𝐡𝐞 𝐜𝐨𝐫𝐞 𝐩𝐫𝐨𝐛𝐥𝐞𝐦: A model can rank beautifully and lie about magnitude simultaneously. When you gate execution on if confidence >= 0.85: approve_transfer, you are trusting a number that was never calibrated to your prevalence, your cost ratio, or your queue. Move the threshold up and you trade recall you never measured for precision you cannot state. You have no idea how far along an unmarked axis you moved.
𝐓𝐡𝐫𝐞𝐞 𝐝𝐞𝐜𝐢𝐬𝐢𝐨𝐧𝐬, 𝐭𝐡𝐫𝐞𝐞 𝐝𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐭 𝐧𝐞𝐞𝐝𝐬:
Routing and ranking consume ordering only - which answer is best matters, the number beside it does not. Gated execution consumes magnitude - the threshold is your boundary and it must land on a calibrated scale. Relative logic like if top1 - top2 < 0.1: escalate consumes differences - and rescaling the score axis will flatten margins unevenly, breaking your code.
The sepsis alert systems of 2020 learned this hard way. Michigan switched off alerts when COVID shifted patient prevalence beneath a fixed threshold. No weights changed. The denominator moved, the promise broke silently, and nurses drowned in false alarms.
𝐓𝐡𝐞 𝐟𝐢𝐱 𝐢𝐬 𝐬𝐞𝐪𝐮𝐞𝐧𝐜𝐞, 𝐧𝐨𝐭 𝐭𝐮𝐧𝐢𝐧𝐠:
First question: is this number admissible as a probability at all? Run a calibration study on a few hundred labelled cases from your own queue. Samuel Sacco's measurements from 18 September and Adil Muhammad Pervez's 8,000 judgments both reach the same conclusion: fit your own map. The weights are shared across every account by design - there is no per-customer adaptation - so a deployer-side calibration map is your only mechanism.
𝐒𝐞𝐜𝐨𝐧𝐝 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧: given that the number is calibrated, where does your cost ratio put the line? That part of the familiar advice still works.
Run them backwards and you are tuning a dial with no markings.
Read the full analysis on calibration, harness placement, and where Jev actually fits:
https://ranjankumar.in/jev-system-one-model-agent-harness-placement
Follow for more practitioner insights on agentic AI systems and production AI engineering.
#AgentiveAI #AIEngineering #SystemOne #Calibration #MLOps #DecisionModels #HarnessEngineering #Jev
Jev has some invisible use cases that won’t be clickbaity but hella useful :
- auto performance checks on your shipped websites
- personal tools like using it for super quick chat compaction
- user feedback prioritisation against most relevant data in your company
- lots and lots of data sorting - quickly
- pairing it with codex / claude to optimise decision making while you code with your agents etc