We used "chain of custody" as our analogy for buildpacks when I was working on them. It's not completely accurate, though, for the same reason as "supply chain

We used "chain of custody" as our analogy for buildpacks when I was working on them. It's not completely accurate, though, for the same reason as "supply chain". There isn't a single linear sequence of agents, actions and assets for a given asset. It's a graph in which things can appear many times in many permutations.