The bus node follows the grants part's sealed user list, and only the grants part reads the vault's hashes (ADR 0547 clauses 7, 9; issue 1945)

The grants part writes its list as an object of its own bucket, sealed to the bus node's key, and names it in
user-list.sealed; the node-engine of the node holding mesh-broker is granted that one key and an object by name, the
grants part its bucket (the controller's copy carries the same grants, byte for byte, golden regenerated there).
A state may name its readers (announce, NamedReaders): mesh-vault.bus-accounts is read by mesh-grants alone.

go/buscompose/announced.go

@@ -45,10 +45,25 @@ func ControllerAnnouncement(node string) announce.States {
 // announced the state readable, or announced nothing yet (the transition); refused when the owner announced and did
 // not announce that state readable.
 func ReadsAnnounced(reads []string, announced map[string]announce.States) (granted, refused []string) {
+	return ReadsAnnouncedBy("", reads, announced)
+}
+
+// ReadsAnnouncedBy is ReadsAnnounced for one reader module, which also honours the readers an owner named for a state
+// (announce.State.Readers) and the composer's named readers (NamedReaders, ADR 0547 clause 9): a read named for other
+// modules is refused. An empty reader is judged by the readable mark alone.
+func ReadsAnnouncedBy(reader string, reads []string, announced map[string]announce.States) (granted, refused []string) {
 	for _, r := range reads {
 		owner, name, ok := strings.Cut(r, ".")
 		s, said := announced[owner]
 		switch {
+		case reader != "" && !ReaderMay(reader, r):
+			refused = append(refused, r)
+		case reader != "" && ok && said && s.Keeps(name):
+			if s.ReadableBy(name, reader) {
+				granted = append(granted, r)
+			} else {
+				refused = append(refused, r)
+			}
 		case !ok || !said || s.Readable(name):
 			granted = append(granted, r)
 		default: