I can look into this. So as I understand it if a page like wikisource:Category:Jv_Basa_Jawa_(Javanese) is connected to d:Q8564118 which also have sitelinks to enwikisource and idwikisource pages, than those 2 should show up as interwiki links on wikisource:Category:Jv_Basa_Jawa_(Javanese).

Commons uses Module:Interwiki for that but that code can only link to wikipedias and does a lot of following properties like 'P301' ( "category's main topic") and 'P460' ( "said to be the same as"), which might not be needed here.

Does multilingual wikisource have pages in several languages which should point to a single wikidata item? if so how ifs it handled?

Generally they probably should not have such pages:

• in the main namespace, each page that should be linked to Wikidata constitutes a separate edition. They should be linked in Wikidata using https://www.wikidata.org/wiki/Wikidata:WikiProject_Books
• in the Author namespace it is possible that there are few Author pages providing the Author name in various languages but this should be resolved internally by creating a multilingual author page in such cases and I do not think we should care of this problem

@Jarekt Multilingual Wikisource also has a Module:Interwiki, which can show interlanguage links based on Wikidata. It works well (although it requires the Qid to be passed manually, but it could be easily rewritten to fall back to the connected Wikidata item), but we’d like to have a native solution, like how c:Category:Javanese language links to w:en:Category:Javanese language when it’s not overridden by the infobox.

@Tacsipacsi Yes your Module:Interwiki relying on connected Wikidata item, is what I had in mind. That is how it is done on Commons with associated template Template:Interwiki_from_Wikidata added to Template:Wikidata_Infobox (with 3M category transclusions) and many other templates.

However if I understand it right you would like this to be hardwired in wikimedia code instead of added by templates?

Yes, I want to have it hardwired, just like how it’s hardwired for all other Wikimedia wikis that are Wikidata clients.

There’s no overwhelming flood of comments, but all three commenters supported this change, and the Scriptorium section has been open for more than three weeks now, so everyone had the chance to express their opinion. Can we now move forward and enable the interlanguage links?

Implementing this is not impossible nor that hard but still has to go through process of prioritization. I add @Lydia_Pintscher who owns that. I want to point out by fixing it, we can also remove the hack from commons as well.

Good from my side, yes. Should this be a separate ticket or part of this one?

Ah ignore my comment...

Is there any progress on this? Almost two months passed since it got green light from @Lydia_Pintscher, and multilingual Wikisource still needs to rely on a custom template.

Sorry this still needed cleaning up by me. I've done that now to get it ready for pick-up by the developers.

Change 697870 had a related patch set uploaded (by Ladsgroup; author: Ladsgroup):

[mediawiki/extensions/Wikibase@master] client: Add support for multiple sitelink groups

https://gerrit.wikimedia.org/r/697870

Change 697870 merged by jenkins-bot:

[mediawiki/extensions/Wikibase@master] client: Add support for multiple sitelink groups

https://gerrit.wikimedia.org/r/697870

Change 698226 had a related patch set uploaded (by Ladsgroup; author: Ladsgroup):

[operations/mediawiki-config@master] Enable wikisource group as langlink group of sourcewiki

https://gerrit.wikimedia.org/r/698226

This can be deployed in two weeks.

I presuming that this will be mentioned in Wikidata weekly summary, It would be great to have this mentioned in a relevant Tech News @Johan that multi-language Wikisource will finally be having active interwiki links from Wikidata.

Two weeks have passed, but I don’t see this in the deployment calendar (even though last week’s Tech News announced it as something that has already happened). When will it be deployed?

This week was wmf allhands and hence no deployment week. Next week (21-28 June), we will deploy it.

Change 698226 merged by jenkins-bot:

[operations/mediawiki-config@master] Enable wikisource group as langlink group of sourcewiki

https://gerrit.wikimedia.org/r/698226

Mentioned in SAL (#wikimedia-operations) [2021-06-21T09:52:22Z] <ladsgroup@deploy1002> Synchronized wmf-config/Wikibase.php: Config: [[gerrit:698226|Enable wikisource group as langlink group of sourcewiki (T275958)]] (duration: 00m 56s)

Finally, thanks! (I knew there was no deployment last week, the thing I was a bit worried about was that I couldn’t find it in the deployment calendar for this week either.) Works for me in Category:United Nations I’ve just connected to Wikidata yesterday.

\o/ tested