Say when the lease is handed away, let the vault and the grants part read it, and let the grants part create the consumers an account needs, so both turn on at the lease write alone (issue 774, ADR 0561 §3, §6)

go/buscompose/create.go

@@ -86,3 +86,30 @@ func ModuleStreamConfig(m ModuleStream) jetstream.StreamConfig {
 	}
 	return cfg
 }
+
+// ConsumerConfig is a pull consumer as the controller's EnsureConsumer creates it (mesh-controller internal/broker
+// JetStream.EnsureConsumer, a consumer not there yet): its durable name, explicit acks, its ack wait, max deliver and max
+// ack pending, its description, one filter or several, and from the stream's end when it is made FromNow. The grants part
+// creates a module's and a process's consumers with it from the lease write (novox/hq ADR 0561 §6): a create alone,
+// never an update of one the bus holds. A push consumer or a queue group is the controller's own and never made here.
+func ConsumerConfig(c Consumer) jetstream.ConsumerConfig {
+	cfg := jetstream.ConsumerConfig{
+		Durable:       c.Name,
+		AckPolicy:     jetstream.AckExplicitPolicy,
+		AckWait:       time.Duration(c.AckWaitSeconds) * time.Second,
+		MaxDeliver:    c.MaxDeliver,
+		MaxAckPending: c.MaxAckPending,
+		Description:   c.Why,
+	}
+	switch len(c.Filters) {
+	case 0:
+	case 1:
+		cfg.FilterSubject = c.Filters[0]
+	default:
+		cfg.FilterSubjects = c.Filters
+	}
+	if c.FromNow {
+		cfg.DeliverPolicy = jetstream.DeliverNewPolicy
+	}
+	return cfg
+}