In late 2015 and early 2016, the Collaboration team worked on building a cross-wiki notification feature: listing notifications from other wikis in the notification panel. We made this feature available on a small set of wikis [1] initially, and about six hours ago we made it available on all wikis as a beta feature.
You can enable cross-wiki notifications by clicking the "Beta" link [2] in the top right corner (or top left in RTL languages) and enabling the "Enhanced notifications" setting. The notification panels (accessible through the bell and speech bubble icons in the top right/left corner) will now display an additional item telling you which other wikis you have unread notifications on, and you can click this item to expand it and see those notifications [3]. For more information, see the documentation on mediawiki.org [4], with mostly complete translations in 13 languages at the time of this writing.
Because we don't have cross-wiki preferences, enabling the beta feature on one wiki doesn't automatically enable it on any other wiki. However, you only have to enable the beta feature to see cross-wiki notifications on a wiki, not to get them from that wiki. For example, if you only enable the beta feature on the French Wikipedia, you will see notifications from the French Wikisource, the Spanish Wikipedia and the Upper Sorbian Wiktionary even if you haven't enabled the beta feature on those wikis. In fact, if you've had an account for a while, you are likely to see some very old notifications from wikis you haven't visited in years; Magnus Manske tweeted a screenshot of this yesterday [5].
Please try this out and let us know what you think! There's a talk page on mediawiki.org [6] where you can leave feedback. If you find a bug, please report it on Phabricator [7] or on the feedback page.
Thanks a lot to the Collaboration team [8] as well as community liaisons Nick Wilson (Quiddity) and Benoît Evellin (Trizek) for their work on this over the past few months.
--Roan Kattouw (User:Catrope)
[1] All French wikis, all Hebrew wikis, Commons, Wikidata and mediawiki.org [2] Or go to [[Special:Preferences]] and click the "Beta features" tab [3] https://commons.wikimedia.org/wiki/File:Notification_panel_with_cross-wiki_n... [4] https://www.mediawiki.org/wiki/Help:Notifications/Cross-wiki [5] https://twitter.com/MagnusManske/status/707712047065210882 [6] https://www.mediawiki.org/wiki/Help_talk:Notifications [7] https://phabricator.wikimedia.org/maniphest/task/edit/form/1/?projectPHIDs=N... [8] https://wikimediafoundation.org/wiki/Staff#Collaboration