I think you mentionned not wanting 5.png (for circuit) to connect to itself even if it was in the right orientation, probably because it would make for really thin chips. The fix to that is to introduce another type of rule to propagate. I learned this when implementing the sudoku for weird rulesets like "knight move".

Basically you have to define if a tile can be adjacent to itself. If it isn't you should propagate that as well when you collapse a tile. Any tile adjacent to the tile we just placed cannot be the same tile.