A plan is ordered by artifacts and says nothing about what must be running before what (ADR 0162);
on 2026-10-03 that put the build machine in tier 0 and the controller in tier 1, and the new build
machine could not bind the worker the old controller had defined. One running order enters the
graph, named as its own edge: a module claiming the build seat follows the control plane, and the
built-by edge from the control plane to that holder yields to it — the controller is built by
whichever build machine is running, as the runtime image always was. The edge orders a plan and
never widens it, like built-by.
jochen
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