@Anomie is there a reason that the MediaWiki API is inconsistent when returning the langlinks of the main page?

• https://en.m.wikipedia.org/w/api.php?action=query&format=json&meta=siteinfo&siprop=general&prop=langlinks&lllimit=max&titles=Main_Page&formatversion=2&llprop=url%7Cautonym%7Clangname&llinlanguagecode=en
• https://en.m.wikipedia.org/w/api.php?action=query&format=json&meta=siteinfo&siprop=general&prop=langlinks&lllimit=max&titles=San_Francisco&formatversion=2&llprop=url%7Cautonym%7Clangname&llinlanguagecode=en

It's returning exactly what the editors provide - see https://en.wikipedia.org/w/index.php?title=Template:Main_Page_interwikis&action=edit

@Legoktm hmm that explains where it's coming from then. Thanks! I 'm not sure we should be encouraging links to "https://en.wikipedia.org/wiki/" (which adds an unnecessary redirect) and an empty string for a title isn't very helpful. With an empty string, an API client that wants to use this information to render needs to not only know about this edge case, but then to handle it, look up the title for the main page before it can request it. I is demonstrated by this PWA API client: https://trending.wmflabs.org/wiki/Main%20Page#/languages (click any link)

From a MediaWiki-Action-API perspective this is a duplicate of T64020. But since I suspect you'll want to use this task to track whatever fix you might make for MobileFrontend, I'm not going to actually close it as a duplicate.

This should be fixed on wiki.
The fact that [[:en]] resolves to the English Main page is very brittle and we shouldn't work around such things in our code.

In T192094#4154053, @Jdlrobson wrote:

The fact that [[:en]] resolves to the English Main page is very brittle

{{citation needed}}

When no title is supplied, either by hitting index.php directly without specifying a 'title' parameter or by supplying the empty string (directly or via $wgArticlePath), the wiki redirects the request to its main page. That doesn't seem fragile and fixing it should it ever break would be an UBN-priority task.

[[en:]] as an interwiki link is equivalent to "supplying the empty string (directly or via $wgArticlePath)", so that's not likely to break either.

@Anome it's fragile in the sense that any client that is not MediaWiki needs to know and workaround this. MediaWiki is not the only thing that displays our content.

cc @Fjalapeno @bearND in case you want to workaround this in MCS.

So it's only "fragile" in the sense that "it's extra work if you want to know the title of the target page ahead of time" rather than any common meaning of the word?

If something needs to be fixed here it likely needs to be done inside the API response for https://en.m.wikipedia.org/w/api.php?action=query&format=json&meta=siteinfo&siprop=general&prop=langlinks&lllimit=max&titles=Main_Page&formatversion=2&llprop=url%7Cautonym%7Clangname&llinlanguagecode=en

e.g. instead of empty string, it should the localized main page title.

Is this something the language team is interested in? If not, I think this task should be declined.