Every resolve stored the rect it computed, however small the move, so float noise in anchor chains moved rects, hit edges and size-change notifications where the reference keeps the old ones.
In the reference, the layout drain compares each of a node's four new edges with the rect it last stored. If every edge moved less than 1e-5 in its units (where the screen diagonal is 1), it keeps the stored rect and skips the store, its dependents and `ApplyRect`. A scale change, a new font or new text clears the resolved bit, so the next resolve stores without the test.
A resolve now keeps a frame's or region's rect under that threshold, scaled by the layout unit, and a scale change or a new measure stores the exact rect.
Tests cover jitter, a move just over, slow drift, a region and the forced stores.
Fixes#919
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
