Appointments: Check-in Event

Hey Guys,
I’m working with a fairly large barber shop (10+ shops) that recently converted to Square Appointments. They’re looking to notify the barbers when a customer checks in. Their old system had one, but Square Appointments does not.

I don’t see an Appointment API yet…
Would it be possible to get an Appointment API or ideally a webhook when a check-in from a customer happens?