Reason
@Nikerabbit in T216480#4974929 :

Translatewiki.net doesn't use the extension anymore. I don't think anybody else uses it either. Wikiapiary is down so cannot check there. I would recommend archiving the extension.

@Nikerabbit in https://gerrit.wikimedia.org/r/#/c/492460/

I wrote this in the task earlier but looks like nobody noticed: "To my knowledge nobody is using this extension. I would recommend archiving the extension."

Should be double-checked though.

To-do list

• This task
  • Add maintainers of that extension as subscribers to this task (if they have no apparent Phabricator account, notify them on-wiki or via email if possible and note it here).
  • Add Phabricator project <#ProjectX> as a tag for this task, or MediaWiki-extensions-Other if there is no project.
• On-wiki documentation
  • Archive documentation on mediawiki.org ( https://www.mediawiki.org/wiki/Extension:FirstSteps ): replace page contents with {{TNT|Archived extension|last revision id before archiving|reason=archive reasons, per [[phab:T226149]]}}; include a link to this task in the reason parameter.
  • If documentation page was translatable, remove <translate>, visit Special:PageTranslation, and click "remove from translation" (if you don't have the translation administrator right, ask a user who does).
  • Archive Wikidata item associated with documentation page ( https://www.wikidata.org/wiki/Q21676755 ) (remove nearly all statements, except instance of (P31) = MediaWiki extension (Q6805426), which should add a qualifier end time (P582) = the YYYY-MM-DD date that you decided to archive extension, generally per edit history, change English (and other languages if possible) description to "archived MediaWiki extension" (and its translation)).
• Phabricator (dedicated project does not exist; no open dedicated tasks to decline)
• Translatewiki.net/translations
  • Remove from translatewiki.net (groups/MediaWiki/mediawiki-extensions.txt) (add translatewiki.net project as a tag for this task).
• Configuration/tests/integrations/etc.
  • Remove from mediawiki/extensions (along with in .gitmodules).
  • Remove tests in [[ https://gerrit.wikimedia.org/g/integration/config | integration/config ]] (zuul/layout.yaml).
• Repositories
  • Empty repository leaving only the README indicating the repo is archived and referring to this task by URL.
  • Mark the repository read-only in Gerrit (Edit description to prepend "[ARCHIVED]" and append Task reference): (https://gerrit.wikimedia.org/r/admin/projects/mediawiki/extensions/FirstSteps).
  • Archive the diffusion repository for the extension: ( rEFIR ).
  • Delete the GitHub mirror: (https://github.com/wikimedia/mediawiki-extensions-FirstSteps).