On touch surfaces the gesture opt-out waited for the viewport to have
already left the end, but streaming corrections re-pin the viewport every
chunk, so the drag never registered: the user could not scroll away
mid-stream, the scroll-to-bottom pill (which waits for a gesture) never
appeared, and live-follow stayed armed — which also made the mobile
load-older button throw the viewport to the bottom, since the prepend's
content growth ran the end correction.
Track the finger's Y between touch events and treat a downward drag (the
touch mirror of wheel-up) as an immediate opt-out. Loading older history
also releases live follow explicitly before the prepend, covering the
case where the button is reachable without any prior scroll.
Bohdan Triapitsyn
4d3542fdb4