Moving from lucene-search-2 to General, this is not a feature request for the search backend. It is a request to add some javascript to the www portals that makes requests to api?action=opensearch.

.. and as such, marked as an invalid bug because this is managed on Meta-Wiki:

• https://meta.wikimedia.org/wiki/Project_portals
• https://meta.wikimedia.org/wiki/Www.wikipedia.org_template
• https://meta.wikimedia.org/wiki/MediaWiki:Gadget-wm-portal.js

This isn't an invalid bug and it doesn't appear to have been resolved. Re-opening.

Like I said, these are maintained on-wiki by the community. We could move them back into version control (e.g. docroot/www.-.org/index.html in operations/mediawiki-config.git) and/or add a Bugzilla component. But right now they are maintained on wiki and requests have mostly been made on the relevant talk pages.

I've created a section for it at https://meta.wikimedia.org/wiki/Talk:Project_portals#Add_search_suggestions_to_wiki-project_portals