jev-pong

# Jev Pong court design Jev Pong simulates a paddle-defense rally: Jev (TypeSafe's System One model) reads the ball's position and velocity every tick and moves the paddle to meet the return. Each hit speeds the ball up, so a long rally outruns the paddle. The agent shapes `pong.json` — the court, the paddle's authority, and the starting ball speed. ## The loop 1. Update `pong.json` (title, courtW/courtH, speed, maxSpeed, accel, and a `style` line that tells Jev a strategy). The viewer watches it and Jev adapts live — no restart, no second server. 2. `node "$JEV_DSH/toolchain/check.mjs"` verifies the workspace's `pong.json` is valid. Run it before you call a court done. 3. Watch the rally. Does Jev return a few balls, speed the ball up, and *sometimes* drop it — or never miss (too easy) / always drop (too hard)? That observation is the finding. ## Reading the court The viewer shows the court, five ghost paddles lit by the probability of each move, a ring where the ball will cross Jev's wall, the paddle's remaining reach, a pace meter with the pace where the paddle is outrun, the text Jev reads, and a bar for every finished rally. Good courts produce a natural arc: Jev holds a few returns, the ball accelerates, Jev scrambles harder, and it finally slips past. `speed` sets the serve pace; `accel` controls how fast each rally runs away; `maxSpeed` is how far a plain paddle move goes per decision (a FAST move goes twice as far). ## Verifying a court `node "$JEV_DSH/toolchain/check.mjs"` returns non-zero when `pong.json` is invalid (no title, or a value outside its range, for example `speed` 1..60 or `stepMs` 30..2000). It also prints the pace past which a far ball is out of the paddle's reach. It doesn't replace watching the motion: confirm Jev holds a low speed comfortably, that raising `speed` or `accel` shortens rallies and raises the miss count, and that the style line shifts how decisively it moves. ## Driving Jev yourself `toolchain/jev.mjs` exports a small client. Example (from the workspace) — ask Jev's read on a state before you commit to a court: ```bash node --input-type=module -e ' import { evaluate, jev } from "$JEV_DSH/toolchain/jev.mjs"; const res = await evaluate({ state: "Keep the rally alive.\nYou are the paddle on the left wall of a 200x120 court. y 0 is the top, y grows downward.\npaddle: centre y 50.0, half-height 13.0, face at x 8\npaddle speed: a plain move shifts it 2.0 per decision, a FAST move 4.0 per decision\nball: x 40.0 y 70.0 vx -6.0 vy 2.0 radius 3 (toward you)\nspeed: 6.0 per decision rally: 0", questions: { move: jev.choice(["MOVE_UP_FAST", "MOVE_UP", "HOLD", "MOVE_DOWN", "MOVE_DOWN_FAST"], "Which paddle move keeps the rally alive?"), }, }); console.log(JSON.stringify(res.answers, null, 2)); ' ``` Without `TYPESAFE_API_KEY` this uses the deterministic mock; set the key to hit live Jev.