Sorry no. CI and monorepos are at best tangentially related. Dependency tracking across repos is a PITA which inhibits code reuse - git sub modules suck as do whatever that alternative git submodule concept is called (subtree?).

Code repos like Cargo and NPM can help but even still it’s an annoying dance to update dependencies in multiple downstream projects. And if there’s a code change you need to make, it’s a 3-way orchestration of new api, update downstream dependencies, remove old api.

That's exactly my point. Cross dependencies is exactly the problem I want CI to solve.

Like the CI system automatically push code commits updating downstream dependencies that reference the upstream repo? Or something else?