situation, very close to conventional flip-flop really.
With each (on table top), put at 90 ° degree points, incredibly, there is a (delicate) positioning that gets each able to illuminate the next, and with enough light to trigger that 'inhibit' response, of suppressing LED output.
Kind of like, 2 'dragons, each consuming the other's tail...', only this is '4' dragons...all around the circle.
I believe that the 4 pin device, is a simple processor, maybe cost less than ¢ 1 cent, (1884 prices).
But that simple, 4 pin, looks like a regular small black plastic transistor.
The little square Solar Cell, on middle of each 'puck', gives off over 1.4 Vdc when in bright light. That is, just the cell, as component, not in circuit.
Guess is, there is the processor to do the LED switch off when daylight, but perhaps some other delay, like 50 mSec from a capacitor, or 'soft' turn on actions, would cause each individual puck, to have a 'palpatle' delay, especially with several or more (in serial order).
At any rate, a simple interruption, of that 'QuadraGate' will 'flip' the total state, but it's really just like having a standard, 2 LED flip-flop, there is just 'another' pair, in lockstep. And, of course, to change that operation back you just 'interrupt' the optical path, with couple fingers
Like I said, it's fun, exploration into switching, while keeping things light; No Wires or pwr supply's, except inside the little pucks.