The other half of needing to use a build system that understands the dependency graph like Bazel is that Bazel _keeps state_, so that it knows which part of the

The other half of needing to use a build system that understands the dependency graph like Bazel is that Bazel _keeps state_, so that it knows which part of the graph does not need to be re-built when you push commit B because it was already built in commit A.