A module hears what it consumes: its consumer is raised with the bus, and it pulls it

Every module moved onto the bus by the rollout was issued on the old one, so none had a consumer
waiting; and the grant named a push delivery a runtime's client never binds, while the pull it
does make — asking about its consumer, asking it for messages — was refused. The consumers a
module's declarations imply are now raised whenever the bus is, and the grant is the pull.

internal/broker/nats_test.go

@@ -338,3 +338,24 @@ func admits(pattern, subject []string) bool {
 	}
 	return len(pattern) == len(subject)
 }
+
+// A module pulls its own consumer — asks about it, asks it for messages — and no other module's.
+func TestAModulePullsItsOwnConsumerAndNoOthers(t *testing.T) {
+	p, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
+		Consumes: []string{"shop.order.placed"}, PasswordHash: "x"})
+	for _, want := range []string{"$JS.API.CONSUMER.INFO.EVENTS.one_audit", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.one_audit"} {
+		if !slices.Contains(p.Publish, want) {
+			t.Errorf("a module cannot bind its own consumer: %v lacks %s", p.Publish, want)
+		}
+	}
+	for _, s := range p.Publish {
+		if strings.Contains(s, "CONSUMER.") && !strings.HasSuffix(s, ".one_audit") {
+			t.Errorf("a module may reach another consumer: %s", s)
+		}
+	}
+	for _, s := range p.Subscribe {
+		if strings.HasPrefix(s, "_DELIVER.") {
+			t.Errorf("a module is granted a push delivery it never binds: %s", s)
+		}
+	}
+}