Alert after duration open multisensor

I am looking to create a smartapp that will alert after an inside door (or anything) is left open for a duration of time. There is a similar function in the Home Monitoring section but then it detects all devices tied with home monitoring (e.g. front door) as well. I am down the path of writing a custom event handler that will kick off a timer and alert after the time has passed. If the door is closed, it’ll cancel the timer.

  1. is there an existing app out there that does exactly this?
  2. is there state in the app/device? - meaning if I create a global variable for storing the amount of time the door has been open, can i access that variable from the open/close event handlers? i may try this method or figuring out a way to “cancel” the runIn().
  3. for the life of me, i can’t find documentation on the specific events that the samsung multipurpose sensor has - is that published in the docs somewhere or do I have to debug to find them?

thanks!

The one in home monitoring under custom allows for the selection of which sensors you want to use and cancels the timer when the door is closed, doesn’t accomplish item 2 as a variable. My use case was a sensor on my freezer door to let me know if it was left open after 10 minutes