Safari 12 improved the security of the browser by killing off the older API. Unfortunately in doing so it killed the very handy Sessions: https://sessions-extension.github.io/Sessions/
I can easily go find the tabs I had open when I upgraded.
My challenge - where do I find a robust tool that remembers all of your tabs even after a crash?
(Yes I know of the preference "reopen open all windows from last session" - past experience says that this doesn't work if the browser crashes).