A finished mesh holds twelve, and two rows were one module each

The substrate's store and the postgres module are the same thing. They were two rows only while the substrate was a different KIND of thing — a store raised from a bundle cannot provide postgres-database, so anything wanting a database needed a second server. It is visible on any mesh built today: mesh-store and postgres, two containers, the same image. Which name survives is settled by the naming rule. Where a consumer speaks a protocol the interface is the protocol, and "database" is not a capability. The control plane's own queries use distinct on and on conflict, so the coupling is to postgres and a "store" module would advertise a swap that fails the first time anyone tries it. The broker collapses the same way with a different outcome: amqp IS a protocol that several implementations speak, so amqp is a legitimate provision and lavinmq is one provider of it. So adopting the substrate is not only an upgrade path — it is two rows of a mesh's module list becoming one, twice. And it leaves nothing that is a specialty after the pivot, which is the claim the whole design rests on and is not true today for exactly those two. Claude-Session: https://claude.ai/code/session_01D6qtiYU3P9jk3pnAXyAFyx
2026-09-15 20:26:42 +02:00
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@@ -51,6 +51,17 @@ rather than a *kind*: how a mesh starts, not what it permanently is.
 duplication as a side effect, and the control plane already reaches its three contexts through
 three separate credentials — which is the shape of a consumer, not an owner.

+**And the module it becomes is `postgres`, not `store`.** The naming rule settles it
+([ADR 0040](../../02-DECISIONS/0040-what-a-module-is.md)): where a consumer speaks a protocol, the
+interface *is* the protocol, and *"database" is not a capability*. The control plane's own queries
+use `distinct on` and `on conflict`, so the coupling is to postgres and a `store` module would
+promise a swap that fails the first time anybody tries it. The broker collapses the same way with a
+different outcome — `amqp` **is** a protocol that several implementations speak, so `amqp` is a
+legitimate provision and `lavinmq` is one provider of it.
+
+So adoption is not only an upgrade path. It is two rows of a mesh's module list becoming one,
+twice.
+
 ## What makes this harder than it looks

 **The recursion is real, not incidental.** The control plane learns what modules exist by reading