Camera-zoom hitch: the FloorplanPanel stays mounted (display:none in 3D mode),
so its navigation-pose subscriber fired every camera onUpdate. During zoom the
view-width changes continuously, so the epsilon guard never short-circuited and
`syncFloorplanViewportToNavigationPose` ran each frame → setViewport/
setFloorplanUserRotationDeg → a full re-render of the ~10k-line floorplan SVG,
even though nothing is visible (React reconciles display:none subtrees).
Gate the viewport sync on `isFloorplanOpen` via a ref the per-frame subscriber
reads, and re-run the mount catch-up effect when the panel reopens so the
viewport snaps to the current camera. The compass is unaffected — it's portaled
to the always-visible viewer area and still receives the pose; only the panel's
own viewport sync is skipped while hidden.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
