Thanks for the feedback everyone.
While @Megamind is correct about the underlying cause for the removal of this feature (WebExtensions forced migration and missing technology in the new Firefox compared to the older versions), I have hope that the latest version of Firefox or at least some of the versions that will be released soon will offer a way for this feature to be redeveloped in a new way - it’s just not going to be a 5 minute job (and since I needed every spare minute to even get the basics implemented in time, this feature had to wait).
Please do contribute to the discussion on GitHub - so far it seems like there are two main use cases of the search feature and we may not be able to implement both. It’s early days yet but the initial feedback seems to suggest that people were mainly using the functionality to replace Firefox bookmarks.
I know it’s not as convenient and certainly an unwanted change but the workarounds described on GitHub will hopefully reduce the pain until we can define and schedule the work to add this feature to Kee 2.0.
PS: @jbsylr wins the secret competition for first use of the rather predictable Kee pun