Heft — github.com/polydawn/heft — is a Layer 3 "planning" tool, which generates Layer 2 computation graphs for execution.

Heft uses info from release databases managed by Hitch to select which versions of Wares to use. The computation graphs Heft produces can be evaluated by Repeatr, and the results of this evaluation are more Wares (which can be put into a new release!).