Question 1

Is this a working calculator, or a demo that deliberately returns wrong answers?

Accepted Answer

A demo, and the failure is the stated point rather than a bug to report. Small sums, differences, square roots and mod often come out right, but on large products it gets the first two or three digits and then stops, because once the digit distribution goes flat, END beats any single digit. No true answer is computed or displayed anywhere in the project.

Question 2

Worker, gateway and Turnstile for a toy - is that a lot of moving parts?

Accepted Answer

The Worker is the part that holds the key, which is where the complexity comes from. It validates the expression grammar and the prefix alphabet, applies a per-IP rate limit, requires a same-origin request plus a short-lived pass minted from a Turnstile token, then forwards exactly one System One choice request. The gateway key is shared by every visitor and capped upstream, so heavy use pauses runs instead of queueing them.

Question 3

Does the model actually choose, or does the code just take an argmax over the probabilities?

Accepted Answer

The API's choice field is used as returned and never an argmax, and every option is offered on every step with nothing masked. That is what makes the streaming view worth reading: you can watch the distribution Jev assigned at each character position, including the moments where END is favoured over a digit and the run terminates early.

Question 4

What happens when the upstream rate-limits me in the middle of a calculation?

Accepted Answer

The browser owns the autoregressive loop in src/runner.ts, with states idle, running, paused, ended, capped, cancelled and error. A gateway 429 pauses the run and shows a Resume button rather than retrying automatically, and the direct TypeSafe fallback has its own smaller budget and limiter. Leave TYPESAFE_API_KEY unset and the fallback is simply disabled, leaving only the gateway path.

Question 5

What options is Jev offered at each step?

Accepted Answer

The same 13 options every step: the digits 0 to 9, a decimal point, a minus sign, and END. Operands can be up to 8 digits and answers up to 12 characters. The page appends whatever Jev picks, then shows the full probability distribution it assigned to each of the 13 options.

Question 6

How do I run the calculator locally?

Accepted Answer

npm install, copy .dev.vars.example to .dev.vars, then npm run dev for Vite on :5173 with /api proxied to wrangler dev on :8787, started separately with npx wrangler dev. Use npm test for unit and workerd tests, and npm run preview for the closest-to-production build.

Question 7

What is the direct TypeSafe fallback for?

Accepted Answer

When the Vercel AI Gateway is rate-limited or failing, the Worker falls back to the direct TypeSafe API using TYPESAFE_API_KEY and a separate small budget and limiter. Leaving that key unset disables the fallback, and JEV_DISABLED is a kill switch.

Jev Calculator

About this project

Highlights

Questions about this entry

More Jev resources like this

From the Jev guides

From the Jev community