ADR 0131: everything on the mesh speaks to the broker seat, and AMQP is not a provision

Taken during the outage of 2026-09-27, when the protocol leaked into the seat's
contract: to hold mesh-broker a module had to provide amqp, so the module that
will carry the bus could not hold the seat that names the bus, while the module
being retired could. Supersedes 0127. Modules depend on the seat and reach the
bus through the sdk; no manifest provides or requires amqp; the old broker's
module and the two modules that required it leave the catalogue; the AMQP
transport is deleted once every node reports on the new bus.

Design 28 step 5 rewritten under it: the seat handover becomes its own task and
is built first, because the seat the control plane dereferences cannot be empty
in between — that emptiness was the outage. The cost note now carries what was
measured rather than what was assumed.

0128 and 0130 extended 0127; each now rests on 0131 with a dated note and
changes nothing it decided. Every other citation of 0127 names its replacement.
records.py still fails on 0120/0112, which predates this branch.

03-DESIGN/01-to-be/25-the-bus-on-nats.md

@@ -10,7 +10,7 @@ code:
 updated: 2026-09-27
 decisions:
   - 02-DECISIONS/0106-the-bus-is-nats.md
-  - 02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md
+  - 02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md
   - 02-DECISIONS/0116-the-bus-is-built-in-five-steps.md
   - 02-DECISIONS/0074-the-wire-is-specified-not-the-types.md
   - 02-DECISIONS/0079-the-foundation-seats-are-named-after-their-servers.md
@@ -303,7 +303,7 @@ the private network. It is raised at genesis like the store, adopted as a module
 phase.
 
 **The deprecated broker is an ordinary module, not a compatibility layer.** Revision, second review
-([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md)): earlier text here, and
+([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseded by [ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md): AMQP is not a provision, and everything speaks to the `mesh-broker` seat)): earlier text here, and
 ADR 0106 before it, called it `lavinmq-compat` — one purpose, the predecessor's clients, and a
 retirement condition of no client connected for a period the operator sets. It is none of those.
 A module may legitimately need an AMQP broker as a **backing service**, the way it needs a
@@ -534,7 +534,7 @@ find what changed and why.
 **Still open:**
 
 - ~~Whether EVENTS should be one stream or one per emitting module.~~ **Closed**
-  ([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseding [ADR 0125](../../02-DECISIONS/0125-the-bus-is-the-only-broker.md))): one stream, and not as a
+  ([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseded by [ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md): AMQP is not a provision, and everything speaks to the `mesh-broker` seat) (superseding [ADR 0125](../../02-DECISIONS/0125-the-bus-is-the-only-broker.md))): one stream, and not as a
   preference — the streams the bus is made of are composed as configuration before any module
   runs, because a provisioner is itself a module that needs a bus account to start. Bootstrapping
   decides it.

03-DESIGN/01-to-be/28-building-the-bus.md

@@ -9,7 +9,7 @@ updated: 2026-09-27
 decisions:
   - 02-DECISIONS/0116-the-bus-is-built-in-five-steps.md
   - 02-DECISIONS/0106-the-bus-is-nats.md
-  - 02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md
+  - 02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md
   - 02-DECISIONS/0126-a-module-declares-its-own-seats.md
   - 02-DECISIONS/0074-the-wire-is-specified-not-the-types.md
   - 02-DECISIONS/0079-the-foundation-seats-are-named-after-their-servers.md
@@ -673,37 +673,42 @@ healthy while reacting to nothing.
       the question it depends on has ever been asked of something real is how the plan's own rule about
       beds gets broken by another route.
 
-      > **What this costs if it goes wrong, measured rather than assumed.** On the installation this is
-      > for, the old broker is also what a whole automation layer outside the mesh connects to — so it
-      > stays, as an ordinary provider of `amqp` ([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md)),
-      > and this step is not its retirement. Nothing in a served request's path goes over the mesh's own
-      > bus: modules serve from their own containers. What a failed move costs is the mesh's ability to
-      > *change* anything — pushes, tool calls, new provisioning — until it is finished or undone. That
-      > is worth knowing before rather than after, and it is why the operator's "as long as my services
-      > keep running" is a reasonable position rather than a gamble.
-- [ ] 5.3 the mesh's own accounts removed from the deprecated broker, and then the broker itself:
-      after the rollout nothing of the mesh speaks to it, and an account nothing uses is one nobody
-      rotates. **It finishes now** ([ADR 0130](../../02-DECISIONS/0130-the-predecessor-is-ending-and-its-broker-goes-with-it.md)):
-      the predecessor is deprecated rather than kept, so once its remnants have stopped the module is
-      unassigned and the port is free. No retirement machinery — a provision with no consumers has its
-      provider unassigned, which is ADR 0127 being paid off rather than revised.
-
+      > **What this costs if it goes wrong, measured rather than assumed.** Nothing in a served
+      > request's path goes over the mesh's own bus: modules serve from their own containers. What a
+      > failed move costs is the mesh's ability to *change* anything — pushes, tool calls, new
+      > provisioning — until it is finished or undone. That is worth knowing before rather than
+      > after, and it is why the operator's "as long as my services keep running" is a reasonable
+      > position rather than a gamble. **Measured on 2026-09-27**, when a seat emptied itself
+      > mid-change: 52 containers stayed up and the broker never stopped; the control plane
+      > crash-looped for two hours and nothing could be deployed until it was repaired by hand.
+      > An earlier version of this note said the old broker stays as an ordinary provider of
+      > `amqp` ([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md)); that is withdrawn by [ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md) — see 5.4.
+- [ ] 5.3 **the seat changes hands as one act.** A command takes a seat and the assignment taking it
+      over, and the seat is never empty in between — the emptiness is the outage of 2026-09-27, when
+      the control plane, which finds its own bus through this seat, lost the address and looped.
+      Today only `seat rename` exists. This is what 5.2 uses to move `mesh-broker` from the old
+      broker's assignment to the new one's, and it is built first ([ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md)).
+- [ ] 5.4 **the old broker and everything that named AMQP leave the mesh** ([ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md),
+      superseding [ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md)): the two modules that
+      required `amqp` are removed, the broker's module is unassigned and removed, registration refuses
+      a manifest that provides or requires `amqp`, and a whole-catalogue check asserts none does. Not
+      a retirement condition — a decision, taken, with the operator's "I don't care if the predecessor
+      breaks" on record ([ADR 0130](../../02-DECISIONS/0130-the-predecessor-is-ending-and-its-broker-goes-with-it.md)).
       Retiring with it: the build outcome's second announcement under the module's own name, which
-      exists only so a catalogue deployed before the rename and one deployed after both hear it.
+      existed only so a catalogue deployed before the rename and one after both heard it.
 
       > **The remote tooling goes with it too.** The predecessor's own mesh talks over that broker, so
       > shutting it down ends the path that reaches this installation's machines from a workstation.
-      > The rollout has to be driven from the node, or driven before the broker stops — which is a
-      > sequencing constraint on 5.2 and not an afterthought.
+      > The rollout is driven from the node, or before the broker stops — a sequencing constraint on
+      > 5.2, not an afterthought.
+- [ ] 5.5 **the AMQP transport is deleted from the control plane and the hosts**, and the variable
+      that selected a transport is refused at start as unknown. One bus, nothing to select ([ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md)).
 
-> **5.4 is gone, and was wrong from ADR 0127 onward.** It read "the deprecated broker retires
-> when its condition holds — no client connected for the period the operator sets", which is
-> ADR 0106's framing of it as a compatibility module with an end date.
-> [ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) settled that it is an
-> **ordinary provider** of the `amqp` provision, like any module answering a backing service:
-> no seat, not foundation, and **no retirement condition**, because the day its last client
-> disappears is not a day anything is waiting for. Removed rather than reworded — a step that
-> waits for a condition nobody set would sit open forever.
+> **The old 5.4 note is history.** It recorded that a retirement *condition* was wrong from
+> [ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) onward, which framed the old broker
+> as an ordinary provider with no end. [ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md) ends that
+> framing in turn: the broker is not kept as a provider either, because AMQP is not a provision. Both
+> readings are kept here so the two reversals can be read in order.
 
 **Done when.** Every node reports on NATS, and nothing of the mesh's own is left connected to the
 deprecated broker.

03-DESIGN/01-to-be/32-what-a-module-declares.md

@@ -357,7 +357,7 @@ controller — because the bus's accounts are configuration rather than somethin
 creates, so there is no provisioner process in the path and nothing waiting on a bus account in
 order to make bus accounts. A module that runs a NATS server of its own and offers it as a
 backing service provides **`nats`**, exactly as the deprecated broker provides `amqp`
-([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md)).
+([ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseded by [ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md): AMQP is not a provision, and everything speaks to the `mesh-broker` seat)).
 
 They are never the same name. A manifest saying `nats` could otherwise mean either the mesh's
 nervous system or a private queue, and the difference between those is the whole architecture.
@@ -427,7 +427,7 @@ it as an ordinary module once the registry exists.
 
 So there are exactly two things the normal path cannot make, both at genesis, both ending the
 moment the mesh can mint for itself: **the bus's own accounts** (§the bootstrap argument in
-[ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseding [ADR 0125](../../02-DECISIONS/0125-the-bus-is-the-only-broker.md)) — a provisioner is a module and
+[ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseded by [ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md): AMQP is not a provision, and everything speaks to the `mesh-broker` seat) (superseding [ADR 0125](../../02-DECISIONS/0125-the-bus-is-the-only-broker.md)) — a provisioner is a module and
 needs an account before it can run) and **the vault's own credential**. Any third exception is a
 design failure, and naming these two is what makes a third one visible.
 

03-DESIGN/01-to-be/README.md

@@ -40,7 +40,7 @@ document is written and this one's status becomes `implemented`.
 | [`28-building-the-bus.md`](28-building-the-bus.md) | **Proposed.** The five steps of the bus work in the order their dependencies allow, each ending at a bed — with the surface measured, so no step's size is a guess | [ADR 0116](../../02-DECISIONS/0116-the-bus-is-built-in-five-steps.md), [ADR 0106](../../02-DECISIONS/0106-the-bus-is-nats.md), [ADR 0074](../../02-DECISIONS/0074-the-wire-is-specified-not-the-types.md) |
 | [`29-a-node-has-operator-accounts.md`](29-a-node-has-operator-accounts.md) | **Proposed.** The mesh models machines but not the humans on them: a node gains operator accounts, and a resource may live under a home owned by its account — what would own ~/.ssh, dotfiles and ~/.config when HAL retires | [ADR 0112](../../02-DECISIONS/0112-a-module-definition-names-no-node-mesh-or-path.md), [ADR 0051](../../02-DECISIONS/0051-shared-data-is-the-operators.md) |
 
-| [`32-what-a-module-declares.md`](32-what-a-module-declares.md) | **Proposed.** What a module declares and what the bus derives from it: three namespaces, subjects from local names, queues never declared, the five relationships, and the build-publish-deploy lifecycle on one bus | [ADR 0126](../../02-DECISIONS/0126-a-module-declares-its-own-seats.md), [ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md) (superseding [ADR 0125](../../02-DECISIONS/0125-the-bus-is-the-only-broker.md)), [ADR 0041](../../02-DECISIONS/0041-events-are-a-relationship.md) |
+| [`32-what-a-module-declares.md`](32-what-a-module-declares.md) | **Proposed.** What a module declares and what the bus derives from it: three namespaces, subjects from local names, queues never declared, the five relationships, and the build-publish-deploy lifecycle on one bus | [ADR 0126](../../02-DECISIONS/0126-a-module-declares-its-own-seats.md), [ADR 0127](../../02-DECISIONS/0127-amqp-is-a-provision-not-the-bus.md), superseded by [ADR 0131](../../02-DECISIONS/0131-everything-on-the-mesh-speaks-to-the-broker-seat.md) (superseding [ADR 0125](../../02-DECISIONS/0125-the-bus-is-the-only-broker.md)), [ADR 0041](../../02-DECISIONS/0041-events-are-a-relationship.md) |
 
 ## Not yet written