@amirthfultehrani rather than using google's bespoke API, have you considered using something like openrouter.ai which allows one to query any model you like via a single API. As for local models, they dont have to be queryable right away, but when designing the config UI and preferences implementation, keep in mind the possibility for their eventual support.
When storing the api keys in prefs, at the very least, obfuscate it, see how relay_password is stored, for an example of doing that.
The content server viewer is indeed the calibre viewer running in a browser.
https://manual.calibre-ebook.com/ser...he-book-viewer
Dont worry too much about the poll results, this feature will be useful to some people in some contexts, as an alternative or even supplement to the existing Lookup feature. And given it is opt in and has zero cost when not used, it wont bother anyone that doesnt want to use it.
Another question, how is the panel trigerred? By a shortcut? By a button in the highlight bar? both?
And finally, the name's Kovid not David.