I mean... Nobody NEEDs to hold a mental model, but we've been increasingly trying to build that mental model into an agentic codebase... maybe we're doing it wrong but it is NOT going well.

The agents jot down absolutely everything (and more, which is the issue), thousands and thousands files of perceived business logic, decisions, workflows, architecture, data modeling, etc... It gets stale extremely quickly - we change one thing in the system and 570 "shards" need to be updated. I stumble on more and more things every day that are untrue about the agents "mental model" and it appears to just keep doing it. One small addition not properly reviewed by a human introduces a cascade of misconceptions system wide.

We've tried these "views" you mention, we call them subsections, but it runs into the same problems. One falsification ends up poisoning entire projects.

Remember when we use to refactor functions in a codebase in order to slim down complexity? Yeah - we ended up doing that but with documentation... IMO code is deterministic and we have trained professionals who know how to read it quickly and modify it. (We don't even need to write it anymore, but reading it is the simplest way to ensure no-loss understanding of a piece of functionality.)