(Edit: Haven't encountered the bug in several game sessions. So it seems to be a rather rare bug.)
BEWARE! There is no automatic saving!
Started playing, couldn't build due to some bug, refreshed and now all my progress is gone.
Interesting, there really should be. (but it is local to your computer).Even though, making backups is still heavily recommended :)
Maybe the bug that prevented me from building also caused the autosave failure. Not sure how to replicate though.