This should be done on global level, if ever.

It shall not configured site local. German WP does not establish any mark to avoid a change in interfaces by editable mark.

@Conny: In my understanding this could be set up by users with managechangetags rights on de.wp.
Could you elaborate which software change would be needed in the MediaWiki codebase itself?

@PerfektesChaos: I'm afraid I don't understand your last sentence, sorry. Could you rephrase maybe?

If at least one tag has been established, revision history will be displayed with an additional checkbox for each revision since registered users will be able to edit tags for this revision.

By accident this happened for undesired site config changes in the past. The change of the user interface was not accepted by the community.

For global tags as issued by extensions it is not possible for users to edit the revision, therefore the interface does not receive a checkbox.

German WP refuses to introduce site tags until wide consensus.

@Aklapper Is it possible to make this happen for all Wikipedias? I can not say, what code change - but [0] needs an addition I think. I can try to check this out.

Reason is, that the procedere is the same and we can improve so quality by watching changes of alt-texts in more languages. We have a survey from Wishlist 2021, that this topic gets some support [1] . We also have support now from user:aka in the Fehlerlisten [2] as a base over 900.000 articles in de:wp that need alt-texts.

[0] https://en.wikipedia.org/wiki/Special:Tags
[1] https://meta.wikimedia.org/wiki/Community_Wishlist_Survey_2021/Reading/Alt-Texts_and_Image_Descriptions
[2] https://de.wikipedia.org/wiki/Benutzer:Aka/Fehlerlisten/Bilder_ohne_Alt-Tag

It is an issue who will monitor edits in which namespaces and trigger tagging.

• On global level this is soemthing around parsing, or similar to mentioning users (notification).
• On site level a cloud tool would be required, which could listen to changes on all WMF wikis.
  • That cloud tool could maintain a database which keeps track of all media identifiers, both site local and commons, via pageid to be robust against file moving.
  • A database could provide image descriptions in a particular language for other pages with transclusion of the same image.
  • Editors could use the text from another page, or use it as base for (automatic) translation and refining in the own language.
  • A JavaScript gadget may be written to be triggered by blind people which would equip the HTML document by alt texts if database knows any image description in an appropriate user language, or might try to provide an automatic translation on the fly.

Tagging edits as requested in this task is not the solution for the goals. It might be one single piece in the jigsaw puzzle for one particular approach. It is not really required. Tagging itself is no solution, and it is pointless without other tools to set the tags, and to evaluate tagged edits.