Short answer: Because Forge saves for you. Every edit applies itself about half a second after you stop typing - or as soon as you press Enter or click away - and the stage updates immediately. The save indicator in the top bar shows saving, saved, and error states so you always know where things stand. Invalid values are never saved: Forge holds them until you fix the field. If you change your mind, Undo steps back.
When an edit saves
An edit commits on its own about half a second after you stop typing. Pressing Enter or clicking away saves right then. Switching to another event also saves whatever you had in progress. You never lose work to a forgotten Save click, because there is no Save click.
Invalid values are never saved
If a field holds something Forge can't accept, the edit is held - not saved - until you fix it. Your project keeps its last good version in the meantime, so a half-typed value or a broken entry can never land in the story your readers would play.
The save indicator
The indicator in the top bar shows three states: saving, saved, and error. If a save fails, the indicator switches to its error state and pins the exact line involved, so you know just where to look instead of hunting for what didn't stick.
Undo, but no Redo
Undo steps back through your recent edits, one at a time. There is no Redo in the story editor - once you undo something, the way to bring it back is to make the edit again. (The Theme and title-screen editors have their own undo and redo.)
Deleting is a deliberate action
Removing an event is never part of autosave - it's its own action, and by default Forge asks you to confirm before deleting. You can adjust that confirmation in Forge's settings.