I drove perhaps 6 miles, and I find it difficult to imagine that there was no oil at all in the engine. It was a bright day so it took awhile to notice the dashboard warnings. Upon returning to my garage I found no oil at all on the dipstick.
The mechanic very quickly poured new oil before he could be stopped, and drained it into his dirty catch basin, so any possibility of checking for metal was gone. This was deceptive and dishonest, which both the service manager and garage owner agree with.
My concern is the unseen damage that may go without a breakdown for years, but may deliver an earlier death to the engine than it might have had, and also make for more noisy engine than it was.