I just picked up a couple Keen home Smart vents and would like to figure out how to do smart zoning.
I know there used to be a third party app inside of SmartThings that you could add to do this with the classic version of smart things. I can no longer find the app.
Your help would be appreciated
Groovy-based Smartapps were shutdown in Jan 2023.
Is there any other way to do smart zoning then?
I haven’t looked into whether there are new Edge drivers that support those smart vents. As of today, we have not seen any community developed Smartapps deployed on the new ST architecture.
You might be able to do a bit of complex rule development in sharptools.io assuming there is an Edge driver for the vents and you have temp sensors to monitor the rooms where you have them deployed.
There are a couple. I don’t want to derail this thread, but I did just want to mention that they do exist. Just not many so far. And none that would help with Keen Vents. 
There’s a list for them in the community-created wiki, but only 4 entries so far, and again, none that would help with Keen devices. 
Carry on.
How do I smart zoning in sharptools?
I’m not intimately familiar with the concept of ‘smart zoning’, but I believe the idea from @h0ckeysk8er is that you could create rules to zone things however you see fit. For example, if you had temperature sensors that you wanted to react to and adjust your vents (alongside thermostat setpoints), you could create rules that use those temperate values and take action on your vents accordingly.
If Temp is at/above XX (precondition)
Motion detected
then Open vent
If No motion for XX or Temp drops below XX
then Close vent
If Temp is at/below XX (precondition)
Motion detected
then Open vent
If No motion for XX or Temp rises above XX
then Close vent
that is what I need.