[ctroein89]

I've learnt that for "What you release together, you should version-control together", the phrase "released together" needs to be defined as "what gets globally updated at once". If you provide anything for customers to implement, you cannot update those globally at once (because you need the customer to update), and should think about using a multi-repo set-up.

My experience is that testing the interactions of historic versions of different components in a mono-repo against each other is difficult. With a multi-repo set-up, one can checkout to whatever historic version one needs to test. That makes it trivially easy to set-up testing that allows one to test historic versions of components against each.