Hi, I use this script to add the number of page to watch in to top right corner of my screen.
But today I've always "1000+" as number, whatever I mark all the watchlist as read.
You can check that by mark it as read and go to https://fr.wikipedia.org/wiki/Sp%C3%A9cial:ApiSandbox#action=query&format=json&meta=userinfo&uiprop=unreadcount
It turns out the direct cause of this is rMW9ea1142fad93: Mark pages on watchlist as visited using JS without reload which caused the "mark all pages as visited" button to start using an API call to action=setnotificationtimestamp instead of calling $user->clearAllNotifications();. That should work, but action=setnotificationtimestamp setting an empty timestamp has been broken since rMWeacec0a22345: add setNotificationTimestampsForUser to WatchedItemStore.