A live rectangle kept every transform in its `xf`, so a non-uniform scale
(a bounding-box drag, Object > Transform > Scale) stretched the rounded
corners built in untransformed space into elliptical arcs. Scale Corners
off divided the radii by the mean scale, which only compensated uniform
scales.
LiveShape::transform now folds a scale along the rectangle's own sides
(any rotation or reflection, no shear) into w/h and keeps only rotation,
reflection and position in `xf`, so the radii are document lengths and the
path is regenerated with circular corners. Radii scale by the mean scale
(sqrt|det|), which keep_corners undoes for Scale Corners off. Shears and
plain moves keep composing into `xf` as before, so files saved with a
scale in `xf` keep their exact geometry until next scaled or rotated.
A corner-widget drag starts from the radius as drawn (clamped to fit).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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