The scene stops heating the MacBook

"Terribly high CPU usage, the MacBook gets really hot" - a fanless MacBook
Air on a 144Hz screen. Measured on that machine with headed engines
(process CPU plus the per-process GPU time macOS keeps): an idle Aero
library cost LibreWolf ~110% CPU and ~230ms/s of GPU, the study feed ~130%,
Chromium up to ~57% CPU and ~350ms/s of GPU, Safari ~220-250ms/s of
WindowServer GPU. Priced one by one:

- the gradient mask on .ice-floats re-rendered the animated layer offscreen
  on every frame (~75 points of Gecko CPU). The floats now rise through a
  plain rectangular band clear of the header, the bottom chrome and the
  rail, and fade in and out inside it, so the clip never cuts a visible one;
- the overlay grain forced a backdrop readback per frame for a texture that
  measured a mean <=0.11/255 difference: removed;
- the invisible blob drift made every frame a full-screen redraw: the blobs
  are painted once;
- static glass (answer tiles, feedback panel, chips, inputs, dropzones,
  lists, segmented controls, Aero hint chips) re-blurred the moving scene
  every frame: only floating glass blurs now, and Aero's baked chat chrome
  drops a live blur that never showed under the bake;
- the scene also parks while the window has no focus and under any dialog
  or sheet scrim (.scene-pause); the loading icon is a compositor-run CSS
  animation instead of a framer-motion main-thread loop.

After, focused and animating: LibreWolf library 109% -> 33% CPU, study
134% -> 34%, chat 130% -> 42%; Chromium GPU 2.5-4.4x lower with 7-22 points
less CPU; Safari's WindowServer GPU -20-26% in Aero, about half in dark.
Unfocused or under a sheet: nothing. bubbles-test sweeps every float through
41 phases against the band and pins the parking and the cost contract;
tests/heat-probe.mjs (macOS) repeats the measurement; the suites find
Playwright's Chromium on macOS.

All 15 suites pass, lint clean, the contrast scan lost a finding. Version
0.6.7, SW v89.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/LoadingState.tsx

@@ -6,6 +6,7 @@ import { useAppReducedMotion as useReducedMotion } from "@/lib/motion-pref";
 
 import { Button, ProgressBar } from "@/components/ui";
 import { useI18n } from "@/lib/i18n";
+import { cn } from "@/lib/utils";
 
 /**
  * The one loading screen for every model pipeline — deck/notes creation,
@@ -80,15 +81,10 @@ export function LoadingState({
     >
       {/* The app icon, not the bare snowflake — same logo as the header,
           sidebar and empty states. */}
-      <motion.div
-        aria-hidden
-        animate={reduceMotion ? undefined : { rotate: [0, 8, -8, 0], scale: [1, 1.08, 1] }}
-        transition={{ duration: 3.2, repeat: Infinity, ease: "easeInOut" }}
-        className="relative size-28"
-      >
+      <div aria-hidden className={cn("relative size-28", !reduceMotion && "loading-bob")}>
         {/* eslint-disable-next-line @next/next/no-img-element -- static app icon, no optimisation needed */}
         <img src="/icons/icon-512.png" alt="" className="size-28 rounded-[1.75rem] shadow-lift" />
-      </motion.div>
+      </div>
 
       <div className="relative w-full max-w-md space-y-3">
         <motion.p