I want to check if a patio door is locked or not remotely. I have a Prop that will check a switch/sensor and communication to the home automation system whether the lock is engaged or not. There are two latches that flip out and go into a receiver slot. I want to put a switch or sensor of some sort inside this plate to know when it is latched. I suppose the options are a plunger or lever switch, optical interruption(emitter below and detector above), proximity or inductive sensor. Optical interruption may be less reliable as the light can bounce around and still hit sensor. The sensor needs to have a long lifespan, the simpler and dumber the better.
I use this Avago Gesture sensor APDS-9960 which measures distance and outputs distance in a value in the Prop, so I can set a threshold to check if there is a reflection in less than 5":
McMaster sells metalic sensors like this which I assume are inductive:
The photo I uploaded shows the latches in the Extended Lock Position.
I can remove the plate with two screws and add something inside the plate. Any ideas on a good way to do this?