I am personally working on formalizing the design stage as well, the core concepts being Architecture, Goal, Solution and Implementation. That would make something like the complexity of an algorithm an explicit decision in a graph. It would make constraints and dependencies explicitly formalized. You can track any code to its solution (design stage) and goals, account for everything top-down and bottom-up, and assign tests for all nodes.

Take a look here: https://github.com/horiacristescu/archlib/blob/main/examples... (but it's still WIP, I am not there yet)