The edge swipe-back armed on the first finger and fired on release even when a
second finger had joined (a pinch-zoom — the board is not .zoomed yet at the first
touch, so the hit-test could not skip it). Track the live pointer count in the
capture phase and cancel the swipe the moment a second pointer joins; the back
navigation fires only for a lone finger. Synthetic-PointerEvent e2e covers both.
Ilia Denisov