As a very happy long-term Session Manager user, I salute your efforts here! Simple and effective. This should help with our Session Manager withdrawal symptoms.

A few thoughts for further refinement:
1) Logo barely visible on gray ribbon. A multi-color icon would help visibility for diverse color needs. Look too at Firefox's closed window/tab icon; white but outlined in black, thus visible on any background really
2) A third save scheme (daily) would be useful, perhaps at first use each day, i.e. 12:01am or whenever Firefox is next open
3) The list of saved sessions might be easier to digest as single line entries; you might need to abbreviate some data, such as save type (Regular (or Interval), Daily, Closed, and User)

Thanks for launching this!

A minimal session manager which does exactly what it advertises. A lifesaver when the Firefox built-in session restore forgets a window or three.

The two (Edit: now only one!) small downsides in my opinion are a) the mentioned missing autosave on exit, or autosaving every 30s but only keeping the newest one, and b) that upon session restore it reloads all tabs - unlike the built-in session restore which loads tabs as inactive or unloaded.

Great Add-on it should be a default option

I wish I had thought of using something like this years ago. Works great on the latest Beta of FF

Finally working session manager on FF57+, THANK YOU!

Very good!

thank you so much