Hi devs,
recently I had a discussion on IRC on how badges for site links should work. After some time I realized that there is a general design issue with their implementation.
The original idea of badges is to replace the FA/GA templates on Wikipedias. This makes sense as it is centralized data which is used in every Wikipedia. On Wikidata we can place that the article about XXX on enwiki is a good/featured article and this will be shown on every Wikipedia having a corresponding article. So basically, we are just removing the {{Link GA|en}} or {{Link FA|en}} template and adding this information to Wikidata. You can see that this is the last step away from the old interwiki system.
However, there are proposals to badges that go far beyond this original idea. Even the yet written implementation has such issues. As everybody will easily understand, an article can be either ga or fa or none. However, it cannot be ga *and* fa together. Thus one sitelink should only be connected to a maximum of one badge. In contrast, the implementation allows more than one badge, even worse, it allows an infinite number of badges. Other proposals want badges to support templates concerning meta information of the local article. However, this information do really *not* concern other Wikipedias. Or can you imagine a Wikipedia that wants to display a "this article needs sources" icon next to the (probably not existing) fa icon? This example makes clear that such meta information that has no value to another Wikipedia than itself should not be stored on Wikidata, too. Wikidata is a place for central data, not any data. For the Wikipedias' internal meta information the working categories work really fine today and there is no reason to force this system into Wikidata without any benefit to Wikidata or the Wikipedias themselves.
So finally, my proposal is to only support one badge per sitelink. And also to only support badges that make sense to have at a central point and that will be used by more than one Wikipedia. I think this makes the ui easier to understand and the code not relying on super-huge config list showing all possible meta information that could be stored as badges resulting in another huge statement system, but even worse.
Please keep this concerns in mind when deciding how the badges should work.
Best regards, Bene*