This would be a super super cool feature.

Main technical issue I see is would be mapping the interwiki prefix to the API url. Especially since we can nest prefixes ([[d:n:b:w:User:Legoktm]] is a valid link).

After that, we just use JSONP to grab the extract/pageimage from the other wiki!

We'd need some design input on this before moving forward.

Just to be bold: there's an ongoing discussion into it.source about hovercards, it has been dreamed a "nested popup", based on a wikidata link; first popup level would list wikidata links to projects about the wikidata entity linked, second level would show the interwiki hovercard of any linked page.

@Jdlrobson thanks:)

As an idea

Adding services as enabling this would probably require access via CORs or locally to other projects. e.g. wikivoyage would need to be able to access summaries from wikipedia. I've not looked into whether this is possible yet :)

In T67117#4620444, @Jdlrobson wrote:

Adding services as enabling this would probably require access via CORs or locally to other projects. e.g. wikivoyage would need to be able to access summaries from wikipedia. I've not looked into whether this is possible yet :)

Unless we make some crazy exception of how we handle things for the summary, this is a matter of a CORS to the summary endpoint indeed. Currently, we allow * in the REST API CORS:

curl -i https://en.wikipedia.org/api/rest_v1/page/summary/Tank | grep access-control

access-control-allow-origin: *
access-control-allow-methods: GET,HEAD
access-control-allow-headers: accept, content-type, content-length, cache-control, accept-language, api-user-agent, if-match, if-modified-since, if-none-match, dnt, accept-encoding
access-control-expose-headers: etag

I'm not quite sure that's enough access, maybe you need some other headers exposed, but IMHO it should be enough to make a CORS for summary.

Hello, who has the new information about this task? :)

In T67117#6072755, @Iniquity wrote:

Hello, who has the new information about this task? :)

If it isn’t mentioned on the task, it probably hasn’t had an update.

This would be useful also for non-Wikimedia wikis linking to Wikipedia.

Change 917950 had a related patch set uploaded (by Sbisson; author: Sbisson):

[mediawiki/extensions/Popups@master] Show page preview popup on interwiki links

https://gerrit.wikimedia.org/r/917950

Change 917950 abandoned by Sbisson:

[mediawiki/extensions/Popups@master] Show page preview popup on interwiki links

Reason:

Will try a different approach next time.

https://gerrit.wikimedia.org/r/917950

In T67117#7317297, @Sophivorus wrote:

This would be useful also for non-Wikimedia wikis linking to Wikipedia.

Big +1. I included that as part of the wishlist proposal (which I should've linked here earlier!) https://meta.wikimedia.org/wiki/Community_Wishlist_Survey_2023/Bots_and_gadgets/Make_Navigation_Popups_%26_Page_Previews_work_cross-wiki - to quote:
"Add a Cross-wiki feature, so that the sister projects can more directly benefit each other, and every MediaWiki installation can get a built-in Wikimedia reference."

Now page previews supports extensibility the best way to do this would be to create a new extension: https://www.mediawiki.org/wiki/Extension:Popups#Extensibility