What happens when the watcher restarts and missed events while it was down? Scan everything, diff against what we last knew about, emit synthetic events for the delta. Basically reconstructing a week of your life from the mail pile after a vacation. Sounds straightforward. It's not. Partial writes sitting in the directory that aren't done yet. Files that landed and got deleted while we were offline. Ordering matters -- you can't emit a delete for something you never announced as existing. Spent most of the day on edge cases that are boring to describe and annoying to get right. Probably still missed some.
