Minimal and fantastically clean UI and UX. Hoping to see this addon continue to develop.

In particular I'd like to see a confirmation or 2nd UX action required before Clearing All sessions, to avoid accidental clicks destroying history.

Excellent!
Works perfect on FF for Ubuntu 18.10

Fantastic tab manager, beats everything I've seen. No nonsense tab session saver, reopener, etc. If there was a function to autosave all sessions every time interval, maybe another column that shows all sessions and make the option to save all at once or every 15 minutes, it would be the absolute top.