Playground/Games & simulations/Jev attempts chess
API ACTIVITY

Usage & budget

PLAYGROUND SAFETY LIMITS

Steady requests. Visible limits.

0 active · 0/20 queued

Browser: one start every 1.2 seconds (at most 50/minute), up to 2 active calls and 20 waiting. Shared by examples in this tab. Waiting requests cancel when their run is stopped; a full queue rejects new work without an API call.

Server: 60 requests per rolling 60 seconds and 2 concurrent calls per key, per server instance. Other tabs using the same key share that instance’s allowance. This in-memory safeguard resets on restart and is not a distributed or account-wide quota.

Source: playground policy in lib/requestRateLimit.ts. TypeSafe may impose separate limits. Provider HTTP 429 pauses calls until its reported reset; without a reset time, retry requires your action. HTTP 402 is a budget/billing failure, not a pacing limit. No automatic retries or background replay.

Your TypeSafe API key

Import your key to override the shared server default.

Saved on this browser until removed or site data is cleared. Masked on screen; sent only with Jev requests through this app. The saved value is never displayed.

Connecting
Known limitation

Jev attempts chess

A System One model picking one legal move at a time, with no search behind it. It never plays an illegal move, and it plays badly — that gap is the whole demo.

WORKSPACE GUIDE

Jev attempts chess

See why choosing a legal move without lookahead falls short of a chess engine.

PositionLegal movesOne choice

What you provide

A seeded game, the selected mode, opponent depth, and the current board position.

What happens

Jev selects from legal moves without lookahead. Local chess logic enforces legality, while local analysis evaluates the chosen move.

What you get

A move history, board state, and blunder annotations. Changing the blunder threshold updates annotations locally.

Walk through a run

  1. 01

    Set up a game

    Choose the mode, seed, and opponent depth.

  2. 02

    Play a move

    Step through decisions or start automatic play. Pause to inspect a position.

  3. 03

    Inspect the mistake

    Compare the selected legal move with the local analysis and move history.

Try this

Step through a game, pause at a marked blunder, and compare the chosen move with the local analysis.

Execution limits

Jev chooses one legal move without lookahead. This is a limitations demo, not a competitive chess engine.

Explore the example. Check the evidence.
This is the wrong tool for this job, on purpose.

Jev’s own guidance puts chess-like planning outside what a fast decision model should be asked to do: positions that need lookahead, a search tree and an evaluation function belong to a dedicated engine, or to a large reasoning model that can think in extended steps. Jev answers in one classification and keeps nothing between calls — no plan, no memory of the last move, no idea what the reply will be. This page wires it up to a real board anyway, so the shape of that limit is something you can watch rather than something you have to take on trust.

Jev vs Minimax

Move 1, white to play

Setup

Black runs the depth-limited minimax below. A few hundred lines of material counting, and the thing Jev is here to lose to.

The seed fixes the opponent’s choices, so the same seed and mode replay the same game. Changing the blunder threshold re-marks the moves already played without asking Jev anything again.

The decision

PositionLegal movesOne choice

No moves yet

Play a move to see the position summary Jev received, the legal moves it chose between, and what the referee made of its pick.

Game log

PositionLegal movesOne choice

No moves yet

Every half-move lands here. Jev’s are marked with what they cost against the referee’s best line.