I'm told that there is an app that will detect wifi connection. I plan on using this in tandem with the garage code. I, too, posted this question recently.
april.brandt:
I just want it to change right away then wait 3.5 hours to reverse everything.
I have two suggestions:
a) Can you give Sarah access to your WiFi? And then use something like @jwetzel1492's iPhone WiFi presence sensor (works with iPhone & Android) to determine when she's left?
b) I have a Fingbox (cost all of $99 a couple years ago). It integrates with IFTTT, and I trigger a Hubitat switch to turn on/off when the Fingbox detects/no-longer-detects Pattie's phone. Using a Fingbox obviates the need to provide access to your WiFi network.
And now, I must go back to watching football 
