Cognitive challenges are handled the way it always has been viz; modularization with well-defined interfaces and contracts, bundled as a software component. See https://en.wikipedia.org/wiki/Software_component and https://en.wikipedia.org/wiki/Component-based_software_engin...

Classic Software Engineering stages of Specification and Verification (both Formal and Informal) take center stage with the software unit being treated as a blackbox. Developers are now "Systems Engineers" responsible for end-to-end systems delivery.

See also my previous comment chain here - https://news.ycombinator.com/item?id=48431591