When using the code search, it would be very useful to preserve the contents of the search query input field at all times when the value of the field is not null.
For example, if I input "SkinTemplateOutputPageBeforeExec" into the search query box, and click any link at the top of the page (Everything · MediaWiki core · Extensions · Skins · Extensions & skins OOUI Wikimedia Operations), the query box will be cleared. This is especially annoying if you want to repeat a search in a different silo. But it's also unexpected if you simply enter the search term, and then decide where to search.
Code from the form if it helps:
element: <input id="q" type="text" placeholder="Search by Regexp" data-reactid=".0.0.0.0" autocomplete="off">
p.s. Thanks for Code Search!