Corrects ADR 0070, written an hour earlier, which had the control plane consuming
the catalogue in order to compose a declaration. That was written before the two
graphs had been told apart and creates a dependency that need not exist: a
catalogue that is down would leave the control plane unable to compose the thing
that would repair it.
The catalogue links module-versions to each other and does not know nodes exist.
The control plane links module-versions to nodes, and holds capabilities and
claims. They meet only when something is installed, and everything between them
travels as events over the broker, on durable queues, so nothing is lost when a
receiver is away.
Build order is not computed anywhere. The builder never consults the graph and
builds what it is asked for; the catalogue asks for the next build after the
previous registration, so ordering holds by construction. Its rule is a condition
rather than a schedule — rebuild once everything a module was built against is
current — which covers a chain and a diamond alike.
Left open: whether an upgrade is applied or merely noticed, and whether a module
on several machines upgrades on all at once.
Claude-Session: https://claude.ai/code/session_01D6qtiYU3P9jk3pnAXyAFyx
