What I’ve done instead is created a WebExtension that uses the omnibox API. In order to execute a keyword search, you simply type the letter “k” followed by a space and then the search. That search will be sent to the Keyword Search WebExtension.

Because I don’t have access to the list of search engines in the browser, I’ve just created a basic set based on the US version of Firefox. You can also set a custom search URL. If you’d like your favorite search engine added to Keyword Search, please let me know.

I’ve also decided to make this a completely different extension on AMO so that existing users are not migrated. You can get the new extension here.