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/store/store.go

@@ -25,6 +25,8 @@ import (
 	"time"
 
 	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/novox/mesh-controller/internal/envfile"
 )
 
 // contextName is what a context may be called.
@@ -67,6 +69,17 @@ func Variable(context string) string {
 // raises the first one.
 func FileVariable(context string) string { return Variable(context) + "_FILE" }
 
+// PortVariable is the environment variable naming the PORT this machine put the store at — the
+// third twin, beside the value and the file.
+//
+// **The connection string is sealed and the port inside it is genesis's** (novox/hq 04-ISSUES/102).
+// The control plane cannot open its own store secret to move the port, and a node's settings can
+// move the store (ADR 0100: the foundation's ports are the node's). Every consumer's binding
+// followed that setting; the control plane's own connection did not, and the mesh was headless. So
+// the port is composed into the control plane's environment from the node's settings, exactly as a
+// consumer's binding is, and the connection string's own port stands only when this says nothing.
+func PortVariable(context string) string { return envfile.PortVar(Variable(context)) }
+
 // Database is what a context's database is called.
 //
 // Named after the context, so that a person looking at a PostgreSQL server can see which
@@ -85,7 +98,7 @@ func Open(ctx context.Context, name string) (*Store, error) {
 				"name, so it must be lower-case letters and digits, starting with a letter", name)
 	}
 
-	dsn, from, err := settingsFor(name)
+	dsn, from, err := placed(name)
 	if err != nil {
 		return nil, err
 	}
@@ -169,6 +182,29 @@ func settingsFor(name string) (dsn, from string, err error) {
 	return direct, Variable(name), nil
 }
 
+// placed is a context's connection string with its port moved to where this machine put the
+// store, when the node's settings say so (PortVariable), and as it was otherwise.
+func placed(name string) (dsn, from string, err error) {
+	dsn, from, err = settingsFor(name)
+	if err != nil {
+		return "", "", err
+	}
+	port, err := envfile.Port(Variable(name))
+	if err != nil || port == "" {
+		return dsn, from, err
+	}
+	moved, err := envfile.WithPort(dsn, port)
+	if err != nil {
+		// The variable and the port are named; the connection string is not, for the same reason
+		// as everywhere else in this file.
+		return "", "", fmt.Errorf(
+			"%s says this machine put the %s store on port %s, and the connection settings in %s "+
+				"could not be read as something with a port in them: %w",
+			PortVariable(name), name, port, from, err)
+	}
+	return moved, from + ", on port " + port + " as " + PortVariable(name) + " says", nil
+}
+
 // Context is which context this store belongs to.
 func (s *Store) Context() string { return s.context }