Dragging the minor-axis grip past the major length re-derived the
perpendicular from the just-swapped major axis on every mouse move, so
the major flipped 90° and the swap re-fired each frame — both axes grew
without bound once the minor reached the major.
Decide which axis the cursor is dragging by projection (not by a perp of
the current major), keep the non-dragged axis fixed, and store the longer
one as the major so the ratio stays <= 1. The swap is now stable across
the circle: the minor holds the old major length while the dragged axis
grows smoothly.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
