Clutch cable broke on engine side
Well, so much for keeping a close eye on the barrel of the clutch cable at the lever end. My clutch cable broke on the engine side! The cable had 23,000 miles on it. The previous one broke at the lever end after 15,000 miles.
It is supposed to be mostly a straight pull at the engine end, so I don't know why it frayed and snapped. I did notice that the pivoting bracket for the very end of the clutch cable was not rotating very smoothly, due to sand in the pivot. That is probably caused by too many muddy puddles and not cleaning the bike.
So, keep an eye on both sides of the clutch cable and have a spare available.