How does chess with Jev differ from an LLM playing chess?

The code, not the model, works out every legal move's facts, and Jev only picks one of them as a single typed Choice. There is no free-form generation, so the move Jev returns is always one of the legal options the engine enumerated.

What are the two packages in the repository?

packages/jev is a small Jev client that prefers the Vercel AI Gateway and falls back to TypeSafe directly, checking answers and reporting cost; packages/chess holds the legal-move facts, the move decision, Chess960 positions, and finished-game scoring on chessops.

Which licence applies to which part?

The Jev client package is MIT and the chess engine package is GPL-3.0. The README makes the split explicit per package, so reuse depends on which half you take.

Can I run the tests without spending on model calls?

Yes. npm test runs the packages' unit tests and npm run typecheck checks the types, both with no Jev calls, so the deterministic half of the logic is verifiable offline.

Does it support chess variants?

Yes. Besides standard browser chess, Chess960 positions are supported, and finished games are scored by the engine package; both are handled through the same legal-move-facts pipeline.

Why does pull requests get read but not merged?

The repository is a mirror of the site's monorepo. Changes happen upstream in that monorepo first and are copied here, so contributions here are read and applied upstream rather than merged directly.

Jev directory

CommunityJev Demos & Experiments

Chess with Jev — cwdx

Browser chess and Chess960 where code works out every legal move's facts and Jev picks one per turn as a single typed Choice; the mirror of the chriswijnia.com/lab/chess monorepo.

See highlights Open github.com

Stars: 0
Language: TypeScript
License: GPL-3.0
Reading time: 2 min
Published by: Community
Author: cwdx
Last verified: Oct 2026

cwdx/chess-with-jev

User repository on GitHub

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Chess with Jev: every legal move's facts worked out in code, Jev's move as one typed Choice. The Jev client (MIT) and chess engine (GPL-3.0) behind chriswijnia.com/lab/chess.

Forks: 1
Last pushed: Updated Oct 2026

Repo stats from the GitHub API, cached Oct 2026.Homepage

This is one of several Jev listings for the same project. The canonical entry is Chess With Jev — Deepender25.

Tagscommunity catalog-import cobanov chess

Works forJev for Decision gating

Used inJev for Gaming

Languages: TypeScript
Platforms: Browser Vercel AI Gateway
Capabilities: Open source

Highlights

Code reduces chess to facts per legal move; Jev receives one typed Choice over those moves per turn.
Two packages split licences cleanly: the small Jev client is MIT and the chess engine is GPL-3.0.
The Jev client tries the Vercel AI Gateway first, falls back to TypeSafe directly, checks answers, and reports cost.
Chess960 positions are supported and finished games are scored; the engine is built on chessops.
Unit tests and typechecking run without any Jev calls.

Quickstart

bash

npm install
npm test          # the packages' unit tests (no Jev calls)
npm run typecheck

Watch out

Copy reviewed against the repo README on 2026-10-15. This repository is a mirror copied from the site's monorepo on every change, so pull requests are read but applied upstream; no pricing or playing-strength benchmarks are published.

Questions about this entry

Short answers drawn from the linked project or page.

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Original write-ups on what this entry is for.

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