Requests for comment/Cross-wiki notifications

Global notifications would be added to the Echo extension. If their account is global (via CentralAuth/shared user table), all of their notifications would be accessible on all wikis they have an account on.

Why do we need global notifications?

 * Current cross-wiki integration for users sucks. [Expand on this]
 * Watchlist wishlist
 * This opens up new notification possibilities as well (well, at least theoretically):
 * An image you uploaded to commons was added to article XX on xxwiki
 * An article you started on xxwiki was linked to an article on xxwiki via Wikidata

User interface

 * User has preference on each wiki whether to see global notifications in the flyout.
 * User options on which notifications are delivered globally, so you can choose any 'mention' would be seen immediately, but a thank (no response needed) isn't (something like this?)
 * This would help with users active on many wikis getting bombed by notifications which may be irrelevant to them
 * There would be some kind of toggle on Special:Notifications to switch between global and local
 * Email notifications would be sent out based on the preferences on the wiki the notification was created on
 * Need some indicator in the flyout that a notification is not from this wiki
 * File:Athena-Wikimania-2012-Echo-BrandonHarris.png and File:Echo-Notifications-Basic.png
 * Doesn't scale well. This works for people active on 1-3 wikis, but not for people who might be active on a few hundred like SWMT members

Backend

 * All notifications are stored in one central database table, with the current schema plus one column indicating which wikid it came from (see )
 * API (meta=notifications) will return global notifications if the user preference is to do so by default. There will be an optional parameter to force or suppress global notifications.
 * Check whether the user is globalized with CentralAuth OR if using a shared user table:
 * Only users with a global account can have global notifications
 * If a user doesn't have a global account, they get echo notifications in the standard manner, split across all wikis

Proposed database schema
current schema