This, I think is the log:
AirPort: Link Down on en0. Reason 8 (Disassociated because station leaving).
This command seemed to help folks back in the Yosemite days:
sudo ifconfig awdl0 down
update: that did nothing. dropping off at Genius Bar. Fingers crossed it’s just an airport card replacement.
Another update: Genius Bar was less than helpful. Tech told me to login as a different user (which I did) to see if the problem still occurred (which it did) and suggested it would be too expense to replace the display where the antennas are located (which is not the problem). Going to drop my beloved MacBook Pro off at a local repair shop this week. Given that the trackpad stutters, the thunderbolt->Ethernet is wonky and occasionally the mouse locks up, I’m thinking it’s likely an I/O board issue. Fingers crossed.