Refuse a send that would seal a placeholder for a bus credential nobody issued (issue 203)

mesh-sdk #141 (issue 774) stands an unissued bus account in, in the Foreseeing mode, so a proposal's answer can be
asked before the vault mints it; the controller's send then took the stand-in for an own secret to make and would
seal a random value where the broker credential belongs. The send and the question refuse it now, in the words the
composition used to: module issue, then push.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

cmd/mesh-controller/compose_perform.go

@@ -86,8 +86,8 @@ func perform(ctx context.Context, open *stores, in *meshInput, node string, d co
 		}
 	}
 
-	// The node's own secrets: a module's superuser password, an administrator, an account. The composition refused what the
+	// The node's own secrets: a module's superuser password, an administrator, an account. A bus credential nobody issued is
-	// send refuses (a bus credential nobody issued, a given value under an old key).
+	// refused before this (unissuedBusCredential), a given value under an old key by the composition.
 	for _, one := range d.StoodIn {
 		module, name, ok := strings.Cut(one, "/")
 		if !ok || strings.Contains(one, " ") {

cmd/mesh-controller/compose_sdk.go

@@ -184,6 +184,9 @@ func composeQuestion(ctx context.Context, open *stores, node string, mode compos
 	if err := refusedBus(in, node); err != nil {
 		return sendable{}, nil, err
 	}
+	if err := unissuedBusCredential(in, node, d); err != nil {
+		return sendable{}, nil, err
+	}
 	sayFound(ctx, d)
 	out := sendableOf(d)
 	out.fileReferences = readsFileReferences(in.Input, node)
@@ -212,6 +215,35 @@ func refusedBus(in *meshInput, node string) error {
 	return nil
 }
 
+// unissuedBusCredential refuses a composition that stands in for a bus credential nobody issued: the module's `broker` own
+// secret (its account `<node>.<module>`) or the provisioner client's (`provisioner.<node>`). A bus credential is minted by
+// `module issue`, never invented: a send that made one would seal a placeholder its process cannot read (novox/hq issue
+// 203). mesh-sdk's composition stands one in, in the Foreseeing mode, since a node's answer to a proposal is asked before
+// the vault mints it (mesh-sdk #141, issue 774), so the send refuses it here, in the words the composition used to.
+func unissuedBusCredential(in *meshInput, node string, d compose.Declared) error {
+	for _, one := range d.StoodIn {
+		module, name, ok := strings.Cut(one, "/")
+		if !ok || strings.Contains(one, " ") {
+			continue
+		}
+		var user string
+		switch name {
+		case "broker":
+			user = node + "." + module
+		case compose.ProvisionerSecret:
+			user = "provisioner." + node
+		default:
+			continue
+		}
+		if !slices.Contains(in.Input.BusMinted, user) {
+			return fmt.Errorf("%s on %s has no bus credential: nothing was issued for %s, and a push would seal a "+
+				"placeholder its process cannot read (novox/hq issue 203). `module issue %s --node %s`, then push again",
+				module, node, user, module, node)
+		}
+	}
+	return nil
+}
+
 // markUnresolvable is an error of a node whose own set does not compose, as planFor marked it.
 func markUnresolvable(err error) error {
 	if compose.IsUnresolvable(err) {
@@ -256,6 +288,10 @@ func composeSendValidated(ctx context.Context, open *stores, node string) (senda
 		if err := refusedBus(in, node); err != nil {
 			return sendable{}, nil, err
 		}
+		// Before perform makes what the composition stands in for: a bus credential is never one of them.
+		if err := unissuedBusCredential(in, node, d); err != nil {
+			return sendable{}, nil, err
+		}
 		if len(byController) > 0 {
 			if d, problems, err = sealedByTheController(in, node, d, byController); err != nil {
 				return sendable{}, nil, err