dismissScaleGain constant
double
const dismissScaleGain
Rate the swipe-to-dismiss shrink loses scale, per unit of the card's own height dragged.
Fitted (with the knee and minDismissScale) to an iOS 26 gesture whose finger position was cursor-tracked through iPhone Mirroring, to an RMS scale error of 0.006. Card height, not screen height, is the normaliser: Maps' small "Map Modes" panel measures ~2.5x per screen height and a medium sheet ~1.4x, but one card-relative gain explains both. A gain below 1.0 per card height is also what lets the shrink pivot at the grabbed point without lifting the card's bottom edge into view (dismissedRect).
Implementation
static const double dismissScaleGain = 0.64;