Overengineering a way to know if people are in my university's CS lab

Love the motivation! Reminds me of the first stuff I built back in my university days.

One thing from and old cranky dev that I notice: it would seem the yml you post has redundancies: either have 4 endpoints, no payload or 4 different payloads, one endpoint (the endpoint itself can tell you what you need to do) However, from the express script it looks like you arrived at this in the final solution anyway. Not sure if I missed something though, is there a reason the API needs such a shape? Cheers!

Hi! Author here. The yml is from a configuration in Home Assistant. Whenever it received an event from the sensors, it would fire the corresponding POST request (which you have to specify ahead of time, hence the configuration being a little redundant). The main reason for switching to the Express setup is that I was having a few random people look at the code & send their own requests to fudge what the status appeared as. I could have added some security/authentication to the endpoints, but I liked the idea of having the frontends simply querying the site (or my proxy) instead of having to cache a POST request.