Does anyone try to do a sort of directional motion sense ? - like when I ENTER the bathroom, turn the light on and when I EXIT the bathroom, turn the light off.
I am thinking of trying to do this (rather than just a timer) so the light goes out sooner when for example, I stumble to the bathroom at night and then back to bed.
Thoughts?
I can't offer you a solution to this, only that I have often thought about this and wanted to do something like this but have always been concerned about how to handle the different situations that can occur, such as someone else entering the same room, etc. You essentially need to maintain a state for presence in the room that is predominantly maintained by motion sensor(s), but they themselves don't typically know which direction you have gone.
As much as I hate coming across all negative about the idea, I guess I'm conscious of setting up rules that become problematic. So if someone has a fool-proof solution then I'm as keen as anyone.
I have also thought at times of using motion in other parts of the house as a way of determining that presence in another room is now finished, which may work in certain situations, but again I've baulked at using this due to the whole multiple people in the house, etc. I didn't want to turn off the bathroom light on someone after me just because I went back to bed 
I've never used it but there is a room manager app, someone developed that dose something like that
Directional Motion sensing is available, but not in any ZWave or Zigbee model. It's easy enough to get a device that provides the indication and perhaps wire it to a Hubduino to pipe it into Hubitat.
Fundamentally it's having two detection 'lines' that are sequential. One's A and the other's B. If A triggers before B then the motion is traveling that direction... and if B triggers before A then the direction is the opposite. Simple enough, but in practicality, it's quite a problem. You could use beam detection.. for example a beam on each side of a door way... You could get a pair of motion sensors and put some tape over the sensor to convert it to a slit (curtain) but that's pretty costly and you can't be certain the message would arrive in the actual order.
Devices specifically made to be curtain sensors would work better, but it's not going to be easy to get the results into Hubitat without some processing dedicated to the timing... which is why I thought about Hubduino.
There seem to be quite a few on Amazon. As @csteele said, no Z-Wave or Zigbee.
Search for Doppler motion sensor.
https://www.amazon.com/dp/B089NKGWQQ/ref=cm_sw_em_r_mt_dp_YtbVFb42XEMEZ
Thanks... this is all very interesting... seems like an open market space for us 
Download the Hubitat app
