Verifies touch-gesture handlers (tap, double-tap, long-press, swipe, pinch, rotate, pan) work as expected under both mobile-emulation (Playwright) and native (XCUITest / Espresso / Detox) - distinguishes "mouse click handler also fires on tap" from "real touch event fired with correct properties." Use when the app has bespoke gesture handlers (custom carousels, sliders, drag-drop, pull-to-refresh) and the team needs targeted gesture verification beyond generic UI assertions.