We want to include the archived talkpages within the Board-search results, so that 14 years of history isn't harder to access than it need be.
Most of the busier pages, include a searchbox within their "Archives list" header-area navbox, eg. https://en.wikipedia.org/wiki/Wikipedia:Help_desk/Header is transcluded into the top of [[WP:Help desk]].
Afaik, they generally use:
(details at https://www.mediawiki.org/wiki/Extension:InputBox )
- Part of https://trello.com/c/nIDJHl8s/
Trello card: qM8FoMxA
- column: Send to Phabricator - Collaboration-Team board
- labels: Questions to figure out (green)