Undo split?

I have again accidentally, with some sweep of the mouse, split an essential and huge document into two. Is there any way to un-split it?
What I’ve done when this happened before is simply copy-and-paste the second half back onto the first, and then put the second document into the trash.
But this is terrifying; it means that I have several versions of the central document I’m using for my book in the trash, but don’t dare to empty the trash.
Please tell me there’s some simple keystroke to undo this splitting of documents?

Yes, just select the two documents you wish to merge back together, and use the Documents/Merge menu command. That will work for large selections of items too. Note you may need to clean up some duplication in the Document Notes field, because the Split feature copies notes over to the new item, and then Merge dutifully merges them back together, resulting in doubled content.

Everything else should be okay—it’s an essentially reversible action to split a document, no more destructive than moving a file in and out of a folder accidentally.

Whew, thanks!

It would be nice to consider a specific “undo” function that could be used for this without applying doubles of notes, etc, in future versions of Scrivener…?

It’s doubtful. There isn’t a good way of doing it technically, because both Split and Merge are a long sequence of automated actions, it’s a bit of a complex thing, really—up to ten different files can be involved.