While writing, does Zettlr have an auto-save feature?
And I noticed, when I manually save (Ctrl+ S) while the doc is open, the undo history is reset - is that correct?
… the Undo-history is reset? That should not be happening. I keep the Ctrl+S-function capable, because it gives an additional feeling of security. Nevertheless, Zettlr currently auto-saves in every situation (so the shortcut is merely for the mental well-being). But the undo-history should only be reset in case you close and re-open the document.