Related:

• T76957: wikimediafoundation.org search results should not include files from Wikimedia Commons
• T94856: Please disable Commons search on OfficeWiki

Adding a small checkbox to Special:Search would be fine, I think. Default should probably be decided per project.

In T96535#1219401, @Glaisher wrote:

Adding a small checkbox to Special:Search would be fine, I think. Default should probably be decided per project.

Wikimedia Commons is one foreign file repository, but MediaWiki can (and Wikimedia likely one day will) support multiple foreign file repositories. Any design should accommodate this, I think.

I'm trying to think of how other sites have solved this problem. Amazon has departments and has a drop-down menu to the left of the text search input, allowing to search a specific department or search all of Amazon. We might want something similar one day, allowing search on the local project (the English Wikipedia), on the local family (Wikipedias), on sister family projects (Wiktionaries, Wikimedia Commons, etc.), or across all public Wikimedia wikis. Whether this should be part of one search interface (Special:Search) or more than one is an open question. How we might reasonably accomplish complex use-cases (e.g., allowing users to search only two specific projects or only three specific project families) in a unified search interface is another big open question.

For files in particular, if the file isn't being used on the local wiki, does displaying it in file search results really make sense? I'm not sure we're matching user expectations here.

In T96535#1223274, @MZMcBride wrote:

We might want something similar one day, allowing search on the local project (the English Wikipedia), on the local family (Wikipedias), on sister family projects (Wiktionaries, Wikimedia Commons, etc.), [...]

Interesting idea. We already have interwiki search but it's not really flexible. It'd be nice to have a search interface with possibilities to search by selecting the languages and projects across Wikimedia.

For files in particular, if the file isn't being used on the local wiki, does displaying it in file search results really make sense? I'm not sure we're matching user expectations here.

When contributors try to find an image for an article, they usually don't go to Commons and search for it. Instead, they just try to find a file by searching locally. So it's not completely pointless to have Commons files in search results.