Jev Trader

Jev Trader market design

Jev Trader shows a live paper-trading desk: Jev (TypeSafe's System One model) reads a synthetic price tape + its own P&L and decides buy / hold / sell each tick. The agent designs market.json — the market Jev trades and the style brief it follows.

The loop

1. Update market.json (instrument, volatility, trend, drift, fee, style). The viewer watches it and reframes Jev live — no restart, no second server. Changing startPrice, capital, seed or episodeDays restarts the paper year.
2. node "$JEV_DSH/toolchain/check.mjs" verifies the workspace's market.json is valid and reports the verdict. Run it before you call a desk done.
3. Watch the equity curve against buy-and-hold and the "right side of the trend" gauge. Does Jev make coherent policy on your market — buy the trend, cut the losses — or just churn? That observation is the finding. .harness/verdict.json carries the same numbers.

Reading Jev

The viewer shows Jev's last action (BUY/HOLD/SELL), shares, equity and confidence. A good desk produces policy: Jev should react to the tape you gave it, not move the same way regardless of your market. A decisive style brief + a real trend yields readable behavior; a flat, driftless market makes any movement look like noise.

Verifying a desk

node "$JEV_DSH/toolchain/check.mjs" returns non-zero when market.json is invalid (bad price, ms, capital). It doesn't replace watching the curve: confirm the market ticks, Jev's equity moves, and its actions vary with the market rather than blindly holding.

Driving Jev yourself

toolchain/jev.mjs exports a small client. Example (from the workspace) — ask Jev's read on a market before you commit:

node --input-type=module -e '
import { evaluate, jev } from "$JEV_DSH/toolchain/jev.mjs";
const res = await evaluate({
  state: "Market: SYNTH, per-step volatility 0.05 with a strong upward drift. Would a momentum Jev be profitable with a buy-the-trend style?",
  questions: {
    edge: jev.noul("Is there a tradable edge here for a momentum trader?"),
    churn: jev.score({0:"no",1:"some",2:"a lot"}, "How much would this market cause needless overtrading?"),
  },
});
console.log(JSON.stringify(res.answers, null, 2));
'

Without TYPESAFE_API_KEY this uses the deterministic mock; set the key to hit live Jev.