Hey Really Cool work. I like the mod. I loaded up a test-save with it and did some experiments. If you connect a belt with a wire to a box and then set the run condition for the belt to something like Iron - Plate > 10000 then the disabled belts functions like a stopper and nothing behind its get spilled. Feels like a way to easy way to cheese the mod, so the only thing you have to do is to disable a Belt at every loose End and the game behaves like normal. I think it would be cooler, if then the not disabled belts would count as loose ends and start spilling stuff.
I was hoping they would get back and fix this, but alas, perhaps they forgot about this mod.
So I went in and vibecoded it. It works better now, but I have not stress-tested it so please complain again if you are getting performance issues.