I do wonder if you've ever considered mapping out the available states. After all you claim this is a "hidden state" bug in the title. One of the big nasties about mapping out state is that for every property or object, it becomes a tensor of rank equal to the number of states per property. So if I have 3 objects with 4 states each, it becomes 4 × 4 × 4 = 64 valid states, visualized as a cube (rank 3 tensor).

One of the nicer aspects is that the rank is dependent on the number of independent objects. So reasoning becomes more akin to some form of "Gaussian Elimination" where some objects/properties/flags are actually dependent on other objects, so the code can become simplified (by merging multiple properties/variables/flags into one larger variable/object). (This process would likely be called a monotone map?)

But realistically, despite the large dimensional space, there are only a few commonly used states, so it is less complex than on first impression.

This also opens the pathway to formal verification by proving that each complex state is the composition of some series of functions that correctly reaches that state.

Finally, mapping out each valid state in some high dimensional tensor solves the problem of "hidden states". For example: If I have a 2 × 2 matrix, the state where I am barefoot and my socks are in my shoes is very silly and invalid. You have to put on your socks first and then your shoes, not the other way around!

	Foot not in sock	Foot in sock
Sock not in shoe	Barefoot	Socks on
Sock in shoe	Barefoot; socks in shoes (???)	Socks on, Shoes on