Broker: the bus node may follow the grants part's sealed user list and the grants part may write it, the operator's second one-grant exception (issue 1945, ADR 0547 clauses 7-8)

internal/broker/users.go

@@ -147,14 +147,19 @@ func Users(r Records) ([]Principal, error) {
 	for _, node := range sortedCopy(r.Nodes) {
 		witness := false
 		var checks []string
+		bus := false
 		for _, d := range r.Assigned[node] {
 			if d.Module == controllerModule {
 				witness = true
 			}
+			if d.SnapshotsTheBus {
+				bus = true
+			}
 			checks = append(checks, d.Checks...)
 		}
 		out = append(out, Principal{Kind: KindNode, Node: node, WitnessesController: witness, Checks: checks,
-			MovesIntoTheVault: servesMoveIn(r), StatesItsKeyToTheVault: servesVerb(r, VaultNodeKey)})
+			MovesIntoTheVault: servesMoveIn(r), StatesItsKeyToTheVault: servesVerb(r, VaultNodeKey),
+			FollowsGrantsUserList: bus})
 		// **And the machine's provisioner client, on an account of its own** (novox/hq ADR 0349 clause 11): one
 		// per machine that runs it, delivered to the module running it.
 		for _, d := range r.Assigned[node] {