Social tools/Echo

Social tools extensions have been progressing to eventually support Echo notifications for different events. Currently, only SocialProfile supports these so far.

Challenge
Challenge doesn't support Echo notifications yet, but it is currently being considered.
 * $1 decided that $2 is the winner of this challenge!
 * $1 decided that you're the winner of this challenge!
 * $1 requested to challenge you!
 * $1 accepted your challenge request.
 * $1 denied your challenge request for the following reason: $2.

Comments

 * $1 deleted your comment for the following reason: $2.
 * $2 commented on your blog "$2".

LinkFilter
There is currently no planned support for Echo within LinkFilter; however, it could possibly be implemented. Such notifications could look something like:


 * $1 denied your link for the following reason: $2.
 * $1 accepted your link!

MediaWikiChat
Although MediaWikiChat does not support Echo notifications, it supports the Web Notification API (also known as the Web Push Notification API). The reason they don't have support for it is because:
 * Echo isn't designed to handle such volume, and doesn't allow you to delete notifications.
 * The Notification API doesn't require interaction between the user and goes away after a few seconds.

MediaWikiChat supports Web Notifications for the following browsers:
 * Chrome
 * Firefox
 * Opera (through Windows 10 notifications system)
 * Browsers that haven't been tested
 * Safari
 * Edge

SocialProfile
SocailProfile's initial echo support was originally added by Ikasty on a fork, which can be seen at https://git.io/v1W5n. It was partially rewritten, expanded on and cleaned up by, and merged by. 
 * SystemGifts

WikiForum
WikiForum doesn't have notifications, but it was worked on by in commit  a few months after ticket #355 at brickimedia/brickimedia on GitHub was created. It has since then been abandoned.

Resources
https://github.com/Brickimedia/brickimedia/issues/257
 * Web Notification API
 * https://www.w3.org/TR/notifications/
 * https://developer.mozilla.org/en-US/docs/Web/API/notification
 * https://developer.mozilla.org/en-US/docs/Web/API/Notifications_API/Using_the_Notifications_API
 * https://notifications.spec.whatwg.org/
 * http://caniuse.com/#feat=notifications
 * Notifications
 * Help:Notifications
 * Help:Notifications/Document a new notification type
 * Extension:Echo