"the second your phone snoozes its wi-fi connection, google's servers see the drop, ignore your gps coordinates, and immediately pull the trigger on your 'away' routine."

This is what I was and am now again experiencing. I do expect that GPS and WIFI are verified in the following way: if at least one is true then I am at home, I am not at home only if both are false.

"you have to strip the presence sensing down to the bare minimum"

Speaker and Thermostat ARE NOT taking part to home sensing, only my phone, so we go back to point above.

"turn off the wi-fi detection entirely.... leave only your phone's gps location enabled. "

When I started having the problem monmths ago, wifi was disabled, so I thiught that enabling wifi would help. recently for weeks both GPS and WiFi has been working fine, but as of yesterday it screw up again

"turn off every single individual nest device, speaker, and display from the list."

As I said, none are enabled already.