Why is SafeEntry not an app???

Store my ic on the app. Put a bt beacon at every building entrance. As i pass by the beacon the app will check in n out.

Or use tracetogether?

Tracetogether is open source right? Run a modified Tracetogether on an android phone at every entrance. Log every instance of tracetogether passing by.

So if you don’t use an android phone. Go get one of those tracetogether dongles.