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/userlist_switch.go

@@ -0,0 +1,111 @@
+package buscompose
+
+import (
+	"slices"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// **The grants part's user list, sealed to the bus node** (novox/hq ADR 0547 clause 7, issue 1945). The grants part writes
+// the list it composed as one object of its own object bucket, sealed to the key of the node holding mesh-broker, and
+// names it in one key of its own state `user-list`. The node-engine of that node follows the key when the switch says
+// so (clause 8), opens the object and writes the bus's user-list file.
+//
+// Who may do what, and nothing more:
+//
+//   - the grants part writes its object bucket (create, put, purge of an object's old chunks, delete) and its own state
+//     as before;
+//   - the node-engine of the node holding mesh-broker reads that one key of the state, watched, and an object of the
+//     bucket by its name: never the bucket's list of names, never a write, never another key of the grants part's state;
+//   - no other principal touches either.
+
+// GrantsUserListBucket, GrantsUserListKey, GrantsUserListObjects and GrantsUserListObjectStream are delivery's names,
+// here where the grants are composed.
+const (
+	GrantsUserListBucket       = delivery.GrantsUserListBucket
+	GrantsUserListKey          = delivery.GrantsUserListKey
+	GrantsUserListObjects      = delivery.GrantsUserListObjects
+	GrantsUserListObjectStream = delivery.GrantsUserListObjectStream
+)
+
+// GrantsUserListFollows is what the node-engine of the node holding mesh-broker may publish to follow the grants part's
+// list: the one key `user-list.sealed` read and watched (its own ordered consumer, filtered on that key alone), and an
+// object of the bucket by its name, as a node reads its declaration's files (ADR 0486 §2: never STREAM.INFO of the object
+// stream, which lists every name, and never STREAM.MSG.GET).
+func GrantsUserListFollows() []string {
+	kv := "KV_" + GrantsUserListBucket
+	key := "$KV." + GrantsUserListBucket + "." + GrantsUserListKey
+	obj, s := GrantsUserListObjects, GrantsUserListObjectStream
+	return []string{
+		"$JS.API.DIRECT.GET." + kv + "." + key,
+		"$JS.API.CONSUMER.CREATE." + kv + ".*." + key,
+		"$JS.API.CONSUMER.DELETE." + kv + ".*",
+		"$JS.API.STREAM.INFO." + kv,
+		"$JS.FC." + kv + ".>",
+		"$JS.API.DIRECT.GET." + s + ".$O." + obj + ".M.*",
+		"$JS.API.CONSUMER.CREATE." + s + ".*.$O." + obj + ".C.*",
+		"$JS.API.CONSUMER.DELETE." + s + ".*",
+		"$JS.FC." + s + ".>",
+	}
+}
+
+// GrantsUserListWrites is what the grants part may publish to keep its object bucket: create it and read its info back,
+// put an object (its chunks and its metadata, the old chunks of a name purged), read an object's metadata, and delete
+// one. Its own state `user-list` it writes already, as every module writes its own.
+func GrantsUserListWrites() []string {
+	obj, s := GrantsUserListObjects, GrantsUserListObjectStream
+	return []string{
+		"$JS.API.STREAM.CREATE." + s,
+		"$JS.API.STREAM.INFO." + s,
+		"$JS.API.STREAM.PURGE." + s,
+		"$JS.API.DIRECT.GET." + s + ".>",
+		"$JS.API.STREAM.MSG.GET." + s,
+		"$O." + obj + ".>",
+	}
+}
+
+// grantsOwnObjects is the grants part writing its own object bucket, and nothing of another.
+func grantsOwnObjects(p Principal, pattern string) bool {
+	return p.Kind == KindModule && p.Module == GrantsModule &&
+		(pattern == "$O."+GrantsUserListObjects+".>" || pattern == "$JS.API.STREAM.CREATE."+GrantsUserListObjectStream)
+}
+
+// **Named readers** (novox/hq ADR 0547 clause 9, progressive insight of 2026-10-26; issue 1945). A state named here is
+// read by the modules named and by no other, whatever another module's `reads` says: the vault's `bus-accounts` holds
+// every bus account's bcrypt hash, and from take-over the grants part alone may read it. A module's announcement may name
+// readers too (announce.State.Readers); both are honoured.
+const VaultBusAccounts = "mesh-vault.bus-accounts"
+
+// NamedReaders are the states only the modules named may read, by `<owner>.<name>`.
+var NamedReaders = map[string][]string{VaultBusAccounts: {GrantsModule}}
+
+// ReaderMay says whether module may read the state read (`<owner>.<name>`) by the named readers: always, for a state
+// that names none.
+func ReaderMay(module, read string) bool {
+	readers, named := NamedReaders[read]
+	return !named || slices.Contains(readers, module)
+}
+
+// readsNamed splits a module's reads by the named readers: those it may read, and those named for others.
+func readsNamed(module string, reads []string) (granted, refused []string) {
+	for _, r := range reads {
+		if ReaderMay(module, strings.TrimSpace(r)) {
+			granted = append(granted, r)
+		} else {
+			refused = append(refused, r)
+		}
+	}
+	return granted, refused
+}
+
+// withNamedReaders is d with the reads named for other modules moved to its refused reads.
+func withNamedReaders(d Declared) Declared {
+	granted, refused := readsNamed(d.Module, d.Reads)
+	if len(refused) == 0 {
+		return d
+	}
+	d.Reads = granted
+	d.ReadsRefused = append(append([]string(nil), d.ReadsRefused...), refused...)
+	return d
+}