phabricator:T5525#2152608 let us know that there is a watchlist survey ongoing, which reads «WMF's Community Tech team is working on a cross-wiki watchlist. This survey will help us understand how you use watchlists, so that we can create a cross-wiki watchlist that works for you. Thank you for participating!». Nemo 07:33, 26 March 2016 (UTC)
Contributions should indicate which are in watchlist
In Preferences, users will eventually discover
 Add pages and files I edit to my watchlist
They will say that is a great idea, and enable it.
But then they will say "what about all those pages I edited when it was unchecked? I wish Contributions had (solid) stars next to pages that are in my watchlist, so I can tell which of my Contributions aren't in my watchlist already (and perhaps even click on empty stars right there in Contributions to add them to my watchlist!)"