Fizlet 0.4.2

• tests: the fx live-scene and input allocation checks use tests/gc.mjs (best of 3 windows); they had lost their perf_hooks import when the GC helper landed, which only failed when a GC actually ran.

Hardening from the engineering review of 0.2.4 (input, sound, embed); each item has a regression test in tests/browser.mjs.

• fizlet/input:
  • Several keys per intent: releasing one of two held keys (A and ArrowLeft) keeps the intent down. Auto-repeat keydowns are not new presses.
  • The pointer and the stick let go on a release outside the target, on pointercancel anywhere and on lostpointercapture (they stayed down before).
  • Multitouch: the pointer and the stick each follow their own pointer id; the stick finger no longer moves pointer.x/y.
  • Pause and destroy drop held keys, press() holds, the pointer and the stick (only window blur did); no ghost press on resume.
  • hit / pointer.hit in a step: a press is seen by exactly one step, the first after it. It was lost when the latching frame ran 0 steps, and seen by every step of a frame that ran several. Outside a step it stays "the frame that latched it", as before.
  • dispose(): remove one controller (listeners, system, held state) without destroying the engine.
  • Pointer events no longer call getBoundingClientRect (one forced layout per event when the page had pending style changes: 2,000 pointermoves on a 3,000-paragraph page took 3.8 s, now 9 ms in Chromium). The read phase measures the target once per frame when the pointer moved.
• fizlet/sound:
  • A custom play installs no AudioContext and no unlock listeners.
  • While switched off, gestures no longer resume a suspended context; switched on, any later trusted gesture resumes one the browser or OS suspended. pointerup also unlocks (touch grants the gesture on release).
  • dispose(): remove the sound provider (listeners, system, close its context) while the engine runs.
• fizlet/embed: close() during a pending lazy load cancels it (the game no longer mounts after being closed); Escape cancels a pending load too, and a later open() starts a fresh one.
• Kernel: systems can have a pause(engine) hook (called when a running engine pauses), and engine.steps (fixed steps run, an integer: reading it in a hot path never boxes).