Help or auto-complete for search terms (or both)

We have ability to use different terms in search queries like: within:, is:completed, parent:

We have a page with list of terms for search:
But once you started flat/global search it’s no way to get link to it.
Also switching back and forth to site not very performant

Could you add auto-complete for this terms (like we have for tags) so creating search queries will be much more faster.

Also please add a link to search article when user already on flat/global search