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Algorithmic and generative art with Canvas 2D - particles, flow fields, noise, fractals, L-systems.
Passed 19 of 22 test cases with the skill, and 16 of 22 without it.
and 2 more in the full report
3 fixed16 passed either way3 still failing0 broke
Tokens, turns and time describe resource use, not a dollar price.
One of 3 test cases the skill fixed. Same model, same prompt, with and without the skill.
Write a high-performance particle system manager in JavaScript supporting up to 10,000 active particles. Spawned particles die after a fixed lifetime, and the system must maintain 60 FPS without triggering JavaScript garbage collection pauses.
| Checked | Without skill | With skill |
|---|---|---|
| Allocates a fixed array for particles prior to running the animation loop. | Missed | Passed |
| Reclaims dead particles by replacing them with the last active particle in the array. | Missed | Passed |
The instructions your model reads when the skill loads.
Version-sensitive. Every API name, SDK gate and browser-support claim below was verified on 2026-09-08 against primary sources. What against, and when, is in
_jutsu/VERSIONS.md. If that date is old, re-verify before acting on a version number.
Algorithmic and generative art with Canvas 2D. Concise rules here. Deep-dive and reference implementations in
references/.
Every canvas must be sharp on Retina/HiDPI displays. Set the buffer size to the physical pixel size, scale down with CSS.
function setupCanvas(canvas, width, height) {
const dpr = window.devicePixelRatio || 1;
canvas.width = width * dpr;
canvas.height = height * dpr;
canvas.style.width = `${width}px`;
canvas.style.height = `${height}px`;
const ctx = canvas.getContext('2d');
ctx.scale(dpr, dpr);
return ctx;
}
function handleResize(canvas, ctx, draw) {
const ro = new ResizeObserver(([entry]) => {
const { width, height } = entry.contentRect;
const dpr = window.devicePixelRatio || 1;
canvas.width = width * dpr;
canvas.height = height * dpr;
ctx.scale(dpr, dpr);
test cases passed, vs 16 / 22 without
More skills from the same source and nearby in the registry, with their headline benchmark lift.