Tagging @Tgr to look over the bullet points above and provide any other insights or precautions, and @Johan for visibility and possible community-facing discussions, and adding iOS folks since I believe they have the same feature that will need similar updates.

Making sure: This is general editing and not the suggested edits feature?

There are aliases, but the documentation is very clear that they should not be used and points to gadgets and other templates assuming one template name.

In T257488#6291672, @Johan wrote:

Making sure: This is general editing and not the suggested edits feature?

It will be both.

In T257488#6291672, @Johan wrote:

Making sure: This is general editing and not the suggested edits feature?

The description editing UI is the same regardless of whether the user came from Suggested Edits or the general article edit-pencil. The Suggested Edits feature presents articles that don't have a description (neither local nor Wikidata), therefore edits resulting from Suggested Edits will always be adding {{short description}} at the top.

I've pinged Wikipedia talk:Short descriptions to give the editors there an early heads-up and make sure we don't take them by surprise. Since I'll be OoO for the next few weeks, I've recommended that they ask any questions or give any feedback in this task, if possible.

In T257488#6305490, @Johan wrote:

I've pinged Wikipedia talk:Short descriptions to give the users there an early heads-up and make sure we don't take them by surprise. Since I'll be OoO for the next few weeks, I've recommended that they ask any questions or give any feedback in this task, if possible.

Cheers @Johan - have a good holiday!

As a specification, this looks reasonable, although it doesn't explain what is going to do this and how.

Note that the local template overriding the infobox only works if the parser function call in the infobox is marked up correctly (T193857). I expect the community is managing that so you won't encounter any problems, just an FYI.

Is it possible for the description itself to contain wikitext and/or transclude other templates? If so, how should we handle those cases? Is there an example of an article that does this?

There isn't really any mechanism for preventing editors from putting anything anywhere (the parser could return an error on save, but can't really differentiate between errors in the article wikitext and errors in some template, so it would be problematic and is not used much for normal pages), so it's technically valid, and back when I wrote the API, it was still debated whether it should be done (see discussion here). The API will display it as-is though, without any wikitext parsing (with only minimal sanitization).

Transcluding other templates is entirely possible (although I'd imagine it's not done in practice).

In T257488#6306029, @Tgr wrote:

As a specification, this looks reasonable, although it doesn't explain what is going to do this and how.

See the proposal(s) in T257944

@Dbrant @Tgr - Is this something that the Core Platform Team can help with or is it being handled already within the Product department? If it's already being handled, what is the estimated timeframe? In other words, when do you expect this to no longer block T256817?

@kaldari I believe the Core Platform team is looking at handling this task (cc @EvanProdromou for timeframes)

I think we've got this on our roadmap discussion, so I'm going to untag the Platform inbox and we'll get this moving.

@eprodromou - I'm a bit confused. Usually untagging a team means you are disclaiming responsibility for it, not claiming responsibility for it.

@Dbrant - If you're not working on this, is it OK if I remove you as the assignee?

This is unfortunate, especially combined with the fact the mobile app displays only the local enwiki description (even when there is none, displaying “+ ADD ARTICLE DESCRIPTION”!), but the edit goes to Wikidata, overwriting the already existing description with the newly added (which is usually worse, obviously). And… the description is still “+ ADD ARTICLE DESCRIPTION” after the edit.