This looks awesome! Seems like a great idea - I'm curious - do you download the full calendar first into a SQLite DB file and then let a user execute queries? SQLite has a "virtual table" feature: https://www3.sqlite.org/vtab.html that could allow "live" queries against the calendar APIs, though my guess is that would be too slow to make sense.

Yes, at the moment there's a batch job to download your calendars and convert them into a SQLite DB. Then, all queries are done directly on that concrete DB (read only).

Originally I was using https://github.com/dolthub/go-mysql-server which is quite similar to the virtual table feature (you just provide a struct which implements some getter methods). Unfortunately I found it a bit slow though (it had to call back into my table many times for even simple queries). Might just be a problem with that implementation and not a limitation of virtual tables themselves so thanks for pointing it out!