If there is something looking like a namespace with entities then use labels and aliases, otherwise use the ordinary opensearch. Keep the search box as close as possible to the existing one, that is have search in the lowermost entry.

• Bug 43774 has been marked as a duplicate of this bug. ***

Gerrit change 49263

Tried the solution in the change, but at least it is missing some way to make the usual search work. It could be some additional field in the drop down that takes the user to the search page, but I think this solution (ie. item selector) should only be available when there are some indication that the namespace is not an entity namespace. That is the search "Wikidata:Project" should list the "Project chat" by using the ordinary title listing, and "Property:head" should list "Property:Head of state" by using the item selector.

(In reply to comment #4)

Tried the solution in the change, but at least it is missing some way to make
the usual search work. It could be some additional field in the drop down
that
takes the user to the search page, but I think this solution (ie. item
selector) should only be available when there are some indication that the
namespace is not an entity namespace. That is the search "Wikidata:Project"
should list the "Project chat" by using the ordinary title listing, and
"Property:head" should list "Property:Head of state" by using the item
selector.

[[mw:Extension:SearchExtraNS]] does something like that (changing search behaviour depending on keyword prefix), maybe it could help. There was also consensus that it should be merged to core (or MWSearch?), in case that helps recycling its logic.

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