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A sandbox where a TypeSafe System One model presses the controls of a small creature. Code runs the world.
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CommunityJev Demos & Experiments
Terrarium
Sandbox where a small creature's controls are chosen by Jev while the code runs the world: one request per step, a Choice over eleven controls plus a per-object fan-out, and a decision log with every probability and every overruled judgment.
- Stars
- 0
- Language
- JavaScript
- License
- MIT
- Published by
- Community
- Author
- TheGali
- Last verified
- Oct 2026
About this project
A sandbox where a TypeSafe System One model (Jev) presses the controls of a small creature. Code runs the world, Jev only ever picks a button, and every decision is logged in full: the state it was sent, every question, every probability, and the rule that fired.
Quoted from the project's README. Read the full README.
Works forJev for Classification
Used inJev for Software & DevTools
- Languages
- JavaScript
Highlights
- One request per STEP carries the world as JSON and answers a Choice over eleven controls plus per-object threat, edible and shelter questions.
- Code decides: it walks the control distribution from the top and takes the first control the world can honour, logging the rejections.
- The decision log is the instrument - every step shows latency, token count, the full probability table and whether code overrule the model.
- No dependencies and Node 20+, and without a key the page runs a mock brain so the game still plays.
Watch out
This is a measurement harness wearing a game UI, and the README is explicit that the decision log is the instrument: every step shows latency, token count, the full probability table and whether code had to overrule the model. Scope is narrower than the visuals suggest. The world is a deterministic simulation - hunger, thirst, fatigue, fear, curiosity, loneliness, warmth and health tick by constants in src/world.js, and nothing the model returns changes a number directly; Jev only picks among eleven controls, and code walks the distribution from the top and takes the first control the world can honour. Setup is Node 20 or newer with no dependencies, and without a key the page runs a mock brain so the game still plays; with a key it is held server-side in serve.mjs and the browser only ever talks to /api/think. What is not documented: tokens or cost per step, any accuracy or calibration figures for the judgments, a test suite, or a license. Copy reviewed against the repository README on 2026-10-04, not from running it.
Questions about this entry
Short answers drawn from the linked project or page.
Advising. Code runs the world and Jev only ever picks a button. The request carries the state as JSON plus a Choice over the eleven controls and a speculative fan-out of per-object threat, edible, drinkable, interest and shelter questions, plus the most pressing drive, an in-danger Noul and a mood Score, all answered in parallel in one round trip of roughly 100 to 400 ms. Code then walks the control distribution from the top and takes the first control the world can honour - an eat with nothing edible adjacent is rejected and the log says so.
That is the point of the project. Every step logs the state that was sent, every question, every probability and the rule that fired, plus latency, token count, the full probability table and whether code had to overrule the model. The author built it to measure how fast Jev answers when a whole world state and a few dozen questions ride in one request, and how accurate the snap judgments are. src/questions.js holds every question and every threshold and is the file to review.
Each free-text drop costs one more request. Jev is asked what the thing is - food type, poison, heat, contact harm, shelter, novelty, alive, behavior, company, icon - and code turns those answers into the same property sheet the built-in palette objects use. The consequences are real rather than cosmetic: eat something Jev judged edible that the world says is poison, and health drops.
Not to try it. Without a key the page runs a mock brain so the game still plays. To go live, get a key from the TypeSafe console and export it as TYPESAFE_API_KEY, or put it in a .env file in the repo root, which is gitignored. The key stays on the server; serve.mjs holds it and the browser only ever talks to /api/think.
It needs Node 20 or newer and no dependencies. Clone the repository, cd into terrarium, and run node serve.mjs 5180, then open http://localhost:5180. Without a key the page runs a mock brain so the game still plays.
One request per step. The state is the world as JSON: species profile, position, eight drives, every object with distance and direction, and the last five events. The questions are one Choice over the eleven controls plus a per-object fan-out of a threat Score, edible Noul, drinkable Noul, interest Score and shelter Noul, plus the most pressing drive, an in-danger Noul and a mood Score, all answered in parallel.
Code decides. It walks the control distribution from the top and takes the first control the world can honour, so eat with nothing edible adjacent is rejected and the log says so. Targets for investigate, hide, flee, eat and drink are resolved from Jev's per-object judgments rather than hard-coded, and the eight drives tick by deterministic constants that no model changes directly.
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