I think it will be sorta handed by T267921: Roll out the Toolbox link for URL Shortener in Wikimedia sites, if we enable the sidebar/toolbox link, it'll become quite prominent

Pre-filling does work: https://meta.wikimedia.org/wiki/Special:UrlShortener?url=https://en.wikipedia.org/wiki/Main_Page
(It's built into MediaWiki's form framework so it works with almost all forms, although you need to snoop around in the page source to find out what the right URL parameter is.)

There's no pre-filled GET processing (e.g. https://meta.wikimedia.org/wiki/Special:UrlShortener/https://fr.wikipedia.org/wiki/Variable_m%C3%A9tasyntaxique doesn't pre-fill the input)

There's. You have to use the url parameter: https://meta.wikimedia.org/wiki/Special:UrlShortener?url=https://fr.wikipedia.org/wiki/Variable_m%C3%A9tasyntaxique

In T288653#7276722, @Tgr wrote:

Pre-filling does work: https://meta.wikimedia.org/wiki/Special:UrlShortener?url=https://en.wikipedia.org/wiki/Main_Page
(It's built into MediaWiki's form framework so it works with almost all forms, although you need to snoop around in the page source to find out what the right URL parameter is.)

In T288653#7276724, @Ammarpad wrote:

There's no pre-filled GET processing (e.g. https://meta.wikimedia.org/wiki/Special:UrlShortener/https://fr.wikipedia.org/wiki/Variable_m%C3%A9tasyntaxique doesn't pre-fill the input)

There's. You have to use the url parameter: https://meta.wikimedia.org/wiki/Special:UrlShortener?url=https://fr.wikipedia.org/wiki/Variable_m%C3%A9tasyntaxique

Adjusted.

Semi-hidden end user documentation at https://meta.wikimedia.org/wiki/Wikimedia_URL_Shortener

w.wiki was never really formally launched because we wanted to get the toolbox link working first, to actually replace the ShortUrl functionality, but we turn it on it for WDQS usage and it's grown organically since then. And further ShortUrl deployments have been halted because it does DB writes on regular page views.

For the most part, people should never visit Special:UrlShortener directly because the toolbox link should be able to give you the short URL of the page you're on already, so we didn't really work on its UX/discoverability. The only time you should end up there is for no-JS users or if you want to shorten a non-MediaWiki link.

There's an etherpad somewhere with a draft announcement and some other notes about launching, but I don't remember the name.

One other way for improving discoverability that we discussed with @JMinor around three years ago in Wikimedia Summit was to use url shortener in "share" functionality in mobile apps. I don't know what's the status of that.

Change 959721 had a related patch set uploaded (by Ammarpad; author: Ammarpad):

[mediawiki/extensions/UrlShortener@master] SpecialUrlShortener: Allow pre-filling url field from subpage

https://gerrit.wikimedia.org/r/959721

Change 959721 merged by jenkins-bot:

[mediawiki/extensions/UrlShortener@master] SpecialUrlShortener: Allow pre-filling url field from subpage

https://gerrit.wikimedia.org/r/959721