diff --git a/server/backend/internal/mqttnotifier/notifier.go b/server/backend/internal/mqttnotifier/notifier.go
index 5260d4d..d064dab 100644
--- a/server/backend/internal/mqttnotifier/notifier.go
+++ b/server/backend/internal/mqttnotifier/notifier.go
@@ -95,6 +95,22 @@ func (n *Notifier) RequestScreenshot(screenSlug string) {
 	token.WaitTimeout(3 * time.Second)
 }
 
+// SendDisplayCommand publiziert einen Display-Befehl (display_on/display_off)
+// auf das Command-Topic des Screens. Retained + QoS 1, damit der Agent den
+// letzten Sollzustand auch nach einem Reconnect erhält.
+func (n *Notifier) SendDisplayCommand(screenSlug, action string) error {
+	if n.client == nil {
+		return nil
+	}
+	topic := fmt.Sprintf("signage/screen/%s/command", screenSlug)
+	payload := []byte(fmt.Sprintf(`{"action":%q}`, action))
+	token := n.client.Publish(topic, 1, true, payload)
+	if !token.WaitTimeout(5 * time.Second) {
+		return fmt.Errorf("mqtt publish display command: timeout")
+	}
+	return token.Error()
+}
+
 func (n *Notifier) publish(screenSlug string) {
 	topic := Topic(screenSlug)
 	payload := []byte(fmt.Sprintf(`{"ts":%d}`, time.Now().UnixMilli()))