In normal (non-kiosk) mode the stage is calc(100dvh - _hdrH), and _hdrH is
measured from HA's chrome, which finishes loading AFTER the card's first
paint — late panels nudged the height and the freshly painted plan visibly
jumped (kiosk is a flat 100dvh, hence 'perfect in kiosk').
Fix, per the owner's sketch:
- until the stage height reads the same twice in a row (200 ms cadence) or
a hard ~600 ms cap, the plan stays hidden (.hpboot) and is revealed only
after a refit — not a single frame paints at a stale height;
- that window is covered by a quiet product-style preloader: dark veil,
small pulsing outline house (the card's own mdi:home-city outline,
inline SVG), no text, 0.15 s opacity fade-out;
- prefers-reduced-motion gets a static house; kiosk never shows the veil;
first open of the card instance only — floor/mode switches are untouched.
smoke_preloader simulates an HA panel landing at t=300 ms and asserts the
veil, zero plan-visible frames at a non-final height, the kiosk opt-out and
the reduced-motion variant; serve.mjs starts every smoke after the reveal,
where the user starts.
