You should pick a text editor that doesn’t throw up a dialog when quitting then. I use CotEditor on macOS specifically for random notes, everything’s unsaved and some notes have survived dozens of reboots over a number of years.

> doesn’t throw up a dialog when quitting then

It doesn't! At least when I Alt+F4 it.

> everything’s unsaved and some notes have survived dozens of reboots

Yep, this is exactly how I use it.

But somehow that one time (note: it was on the shutdown) something went terribly wrong.

I wonder if your notes were borked out of session.xml, but the files were still available at AppData\Roaming\Notepad++\backup.

I've changed machines where the user profile was in a different location, copied my AppData, and replacing the old location in Notepad++'s session.xml was enough to restore my unsaved notes.

Nah.

Of course I tried everything (except looking in the shadow copy? Don't remember), but in the essence the shutdown triggered Save All workflow (somehow) and I responded with 'No'.

*weep*