Use :Obsess (with optional file/directory name) to start recording to a session file and :Obsess! to stop and throw it away. That's it. Load a session in the usual manner: vim -S, or :source it.
But as far as I can tell the command is :Obsession and :Obsession!
Documentation says:
But as far as I can tell the command is :Obsession and :Obsession!
Digging this plugin, thanks for sharing!