Excellent post, thank you.

I've run into similar challenges in a number of (mostly microservice) systems that also avoided monorepos (for various practical and philosophical reasons). Parts of the solution space here are very familiar, especially relating to dependency management and "goldilocks" framework infrastructure.

I've especially found that most cloud CI tools (e.g. Circleci) fall flat here without a lot of additional work. Those ecosystems seem designed for a single repo; there's a big opportunity for someone to get CI right for non-trivial, multi-repo projects.