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alternatively, this is how I had Joey set up and I really like this flow:
scrolling past a post marks it as viewed. options exist for "scrolling past = viewed" and "opened post = viewed".
a "hide viewed" button easily accessible from the feed (ie in a pop-up menu on a floating circular button in the bottom corner) lets me hide everything I have seen at once.
The problem I have with auto-hiding read is that sometimes I want to scroll back up to look at something again.