Adds .js to the piece-resolution fallback chain. When matched, disk.mjs synthesizes a stub module via lib/p5-iframe.mjs that uses dom.html to mount /aesthetic.computer/dep/p5/p5-host.html?src=<sketch-url>. The host page imports p5.js (jsdelivr), fetches the sketch, and runs it in global mode. Worker boundary preserved. Demo at disks/p5-bounce.js. Architecture trade-offs in reports/p5js-integration-exploration.md — recording/preview don't flow back through AC's compositor under this approach; Option B (OffscreenCanvas-patched p5 in the worker) can layer on later.