Wait to mark an item as read until the user has scrolled to the next item
Instead of marking items as read once the user starts scrolling, wait until they've scrolled to the next item. This way half-read items will still be "new" (if you accidentally close the window or open on another device).
This would solve https://bazqux.uservoice.com/forums/190752-general/suggestions/6383547-way-to-get-the-previous-read-post, as a side effect, and is probably easier to implement.
Kristina Chodorow shared this idea