yeah, the preview is very raw; keep in mind I wrote this in a few hours
correct, threads vs OP tweets is tweets you started that have more than at least one response from yourself to the tweet, whereas "OP tweets" are just tweets you authored even if you didn't create a thread.
I made one default because, I don't know, I thought it made sense
and yeah, I noticed the bug where after clicking generate events you'd need to restart if you want to change the selection -- need to fix