No, current models and tools are more than capable of dissecting entire codebases.

And even if they somehow weren’t, we’d just do what we used to do with documents to turn them into "chewable bites": chunking, extracting, summarising,…

Huh? Even if progress somehow stopped, current models are already good enough to help -- and the quality of a given vibe-coded throwaway codebase will be higher the more recently it was created.