But that dependency order is usually just one big blob of ”COPY src/ . + RUN make”, within that block you have none of the benefits. Bazel/Buck has much finer awareness down to every individual file.

Out of curiosity, would it be feasible to take a big cmake project and generate thousands of compile rules into dagger and use it as a substitute for make with sandboxing? I’ve never seen builkit used with such many nodes, how would it fare?

Dagger is a declarative DAG engine. So, yes, you can do that.

There is an overhead per container launched so it would probably not be worth it.