Merge pull request 'The move ends with the old broker going, not staying' (#90) from fix/rollout-retires-the-old-broker into main

cmd/mesh-controller/rollout.go

@@ -25,11 +25,11 @@ import (
 // against a mesh that is serving. It answers from records: what is missing, and what would happen.
 // `rollout` itself refuses unless the check is clean.
 //
-// **The old broker is not switched off by this.** It stays an ordinary provider of `amqp` for whatever
+// **The old broker goes with the move, and goes last** (novox/hq ADR 0131): AMQP is not a provision,
-// else uses it — on this installation, a whole automation layer that has nothing to do with the mesh
+// so once every machine reports on the new bus its module is unassigned. Only the mesh's own traffic
-// ([ADR 0119](../../02-DECISIONS/0119-amqp-is-a-provision-not-the-bus.md)). Only the mesh's own
+// is what moves, which is why this is survivable at all: what breaks if it goes wrong is the mesh's
-// traffic moves, which is why this is survivable at all: what breaks if it goes wrong is the mesh's
+// ability to change things, not the services its modules are serving — measured on 2026-09-27, when
-// ability to change things, not the services its modules are serving.
+// a seat emptied mid-change and the control plane looped for two hours while every service stayed up.
 
 const rolloutUsage = "rollout check | rollout --confirm"
 
@@ -105,7 +105,6 @@ func readinessOf(ctx context.Context, inv *inventory.Inventory) (broker.Readines
 		ModuleCredentialled: map[string]bool{},
 		// The old broker keeps its other clients on this installation, and saying so is how the plan
 		// stops reading as a retirement.
-		OldBusHasOtherClients: true,
 	}
 
 	address, _, err := broker.OnNATS()

internal/broker/readiness.go

@@ -35,10 +35,6 @@ type Readiness struct {
 	Modules []string
 	// ModuleCredentialled is which of those has one.
 	ModuleCredentialled map[string]bool
-	// StillOnTheOldBus is whether anything of the mesh's own still needs the bus it is leaving —
-	// which is not a reason to stop, because that broker stays as an ordinary provider of `amqp`
-	// (ADR 0119). Recorded so nobody reads the move as a retirement.
-	OldBusHasOtherClients bool
 }
 
 // NotReady is every reason this mesh cannot move its bus yet, in the order somebody would fix them.
@@ -120,10 +116,11 @@ func WhatMoves(r Readiness) []string {
 		out = append(out, fmt.Sprintf("move %d module runtime(s), and confirm each answers",
 			len(r.Modules)))
 	}
-	if r.OldBusHasOtherClients {
+	// **The old broker goes, and it goes last** (novox/hq ADR 0131). AMQP is not a provision, so once
-		out = append(out, "leave the old broker running: it stays an ordinary provider of `amqp` for "+
+	// every machine reports on the new bus nothing of the mesh is left speaking to it, and its module
-			"whatever else uses it (ADR 0119), and this move is not its retirement")
+	// is unassigned. Said as a step so nobody reads the move as leaving a second bus behind.
-	}
+	out = append(out, "then unassign the old broker's module: AMQP is not a provision (ADR 0131), and "+
+		"once every machine reports on the new bus nothing of the mesh speaks to it")
 	return out
 }
 

internal/broker/readiness_test.go

@@ -79,9 +79,8 @@ func TestEachThingMissingNamesItsOwnRemedy(t *testing.T) {
 
 // What the move would do is written out rather than summarised, because this is the one step with
 // nothing to inspect afterwards — so reading it is the last chance to disagree.
-func TestWhatMovesNamesEveryMachineAndSaysTheOldBrokerStays(t *testing.T) {
+func TestWhatMovesNamesEveryMachineAndEndsWithTheOldBrokerGoing(t *testing.T) {
 	r := aMeshReadyToMove()
-	r.OldBusHasOtherClients = true
 	steps := strings.Join(WhatMoves(r), "\n")
 
 	for _, want := range []string{"anchor", "laptop", "user list", "module runtime"} {
@@ -89,9 +88,11 @@ func TestWhatMovesNamesEveryMachineAndSaysTheOldBrokerStays(t *testing.T) {
 			t.Errorf("the plan does not mention %q:\n%s", want, steps)
 		}
 	}
-	// Said explicitly, so nobody reads the move as switching the old broker off — it stays serving
+	// Said explicitly, and last: AMQP is not a provision (novox/hq ADR 0131), so the move ends with
-	// whatever else uses it, and that is a decision already taken.
+	// the old broker's module unassigned, not left behind as a second bus. An earlier version of this
-	if !strings.Contains(steps, "not its retirement") {
+	// test pinned the opposite, under a record 0131 superseded.
-		t.Errorf("the plan does not say the old broker stays:\n%s", steps)
+	lines := WhatMoves(r)
+	if last := lines[len(lines)-1]; !strings.Contains(last, "unassign the old broker") {
+		t.Errorf("the plan does not end with the old broker going:\n%s", steps)
 	}
 }