thanks for the design.
I did build a unit in 2018.
Today I build one to control the light on my front door. It will be triggered by the IR Motion sensor.
The Switch indoors will be just to power the light (and the arduino) off completly.
Because of the IR Sensor VCC near the PIN 4 GND GND PIN7 Header.
I routed my own with a wire.
Never have I soldered a slow blow fuse in one go