An address is read from the node's settings where it is used, never recorded with a port

Three readers did not follow a moved foundation port (novox/hq 04-ISSUES/102),
and each took the control-node down in its own way: the control plane's own
store and broker connections, sealed at genesis with the port inside; and every
build the mesh ever recorded, kept as `<registry>:<port>/<module>/<artifact>@…`.

The control plane cannot open its own sealed connections to move a port, and it
cannot bind the store as a consumer would — a binding mints a credential. So its
settings get a third twin, `NAME_PORT`, read on top of the sealed value by the
store, the broker, the management API and the bus connection, and filled into
its container by a placeholder that names a seat, `${seat:mesh-store:5432}`,
from the node's given or mesh-assigned ports — never the manifest's number, and
empty when the mesh has nothing to add, so what genesis wrote stands. A value
that is still a placeholder is nothing said, aloud: the manifest naming it lands
in the next commit, once every control plane that composes it knows it.

A build is now recorded by digest and path — `artifact-store://<module>/<artifact>@…`
— and the store's address is composed in where a reference is used: the
declaration, the trust file, the bases a build is handed, a replay to the
catalogue. Over the network as `<node>.internal:<port>`; on the store's own node
before any network exists — every genesis push before its "network" step — by
loopback. A reference recorded before this, with an address, is re-routed the
same way when the mesh built it. The trust file and every provider's address
come from one derivation: the node's given port, over the mesh's assignment,
over the manifest's number.

novox/hq 04-ISSUES/102

internal/broker/broker.go

@@ -40,8 +40,12 @@ type Broker struct {
 var ErrNotConfigured = errors.New("this control plane has not been told about its broker")
 
 // FromEnvironment reads the two settings, if they are there.
+//
+// The address's port follows MESH_BROKER_ADDRESS_PORT when the node's settings moved the bus
+// (novox/hq 04-ISSUES/102): the address genesis wrote is a public name and the port genesis
+// chose, and only the port is the node's to move.
 func FromEnvironment() (Broker, error) {
-	address, err := envfile.Value(AddressVar)
+	address, err := envfile.Placed(AddressVar)
 	if err != nil {
 		return Broker{}, err
 	}

internal/broker/broker_test.go

@@ -178,3 +178,32 @@ func TestBothTogetherGiveABroker(t *testing.T) {
 		t.Errorf("got %+v", known)
 	}
 }
+
+// The node moved the bus, and the address a token carries follows (novox/hq 04-ISSUES/102).
+func TestTheAddressPortFollowsThePortTwin(t *testing.T) {
+	t.Setenv(AddressVar, "broker.example:5671")
+	t.Setenv(AddressVar+"_FILE", "")
+	path, _ := writeCertificate(t)
+	t.Setenv(CertificateVar, path)
+	t.Setenv(AddressVar+"_PORT", "5679")
+	b, err := FromEnvironment()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if b.Address != "broker.example:5679" {
+		t.Fatalf("the address is %q; the node put the bus on 5679", b.Address)
+	}
+}
+
+func TestTheManagementPortFollowsThePortTwin(t *testing.T) {
+	t.Setenv(ManagementVar, "http://guest:guest@127.0.0.1:15672")
+	t.Setenv(ManagementVar+"_FILE", "")
+	t.Setenv(ManagementVar+"_PORT", "15673")
+	m, err := ManagementFromEnvironment()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if m.base.Host != "127.0.0.1:15673" {
+		t.Fatalf("the management API is at %q; the node put it on 15673", m.base.Host)
+	}
+}

internal/broker/management.go

@@ -41,8 +41,11 @@ type Management struct {
 }
 
 // ManagementFromEnvironment reads where the management API is, if it is configured.
+//
+// On the port MESH_BROKER_MANAGEMENT_PORT names when the node moved it (novox/hq 04-ISSUES/102);
+// the URL's own port otherwise.
 func ManagementFromEnvironment() (*Management, error) {
-	raw, err := envfile.Value(ManagementVar)
+	raw, err := envfile.Placed(ManagementVar)
 	if err != nil {
 		return nil, err
 	}