OptionalonWhat the app sends on a swipe — run with the item that was in front and the one now in front, typed as the feed's own item handles (their data is on them, so a caller names the items it swiped between without narrowing). Without it a swipe sends nothing of its own.
What
swipeableFeedtakes — facts of the screen, each the app's own:onSwipe, what the app sends on a swipe — run with the item that was in front and the one now in front. Without it a swipe sends nothing of its own. Viewing is the item's visit: its ownenterruns when it comes in front and itsleavewhen a swipe moves it away — there is no separate viewing action.nextPageWhenItemsLeft, the prefetch threshold: the swipe that leaves this many loaded items or fewer after the one in front requests the next page. Without it the next page is requested only when the swipe has no loaded item to go to.