diff --git a/firmware/components/message-manager/include/message_manager.h b/firmware/components/message-manager/include/message_manager.h
index 6274aa3..df32389 100644
--- a/firmware/components/message-manager/include/message_manager.h
+++ b/firmware/components/message-manager/include/message_manager.h
@@ -57,6 +57,10 @@ extern "C"
         } data;
     } message_t;
 
+    // Observer Pattern: Listener-Typ und Registrierungsfunktionen
+    typedef void (*message_listener_t)(const message_t *msg);
+    void message_manager_register_listener(message_listener_t listener);
+    void message_manager_unregister_listener(message_listener_t listener);
     void message_manager_init(void);
     bool message_manager_post(const message_t *msg, TickType_t timeout);
 
diff --git a/firmware/components/message-manager/src/message_manager.c b/firmware/components/message-manager/src/message_manager.c
index b3bc810..b628138 100644
--- a/firmware/components/message-manager/src/message_manager.c
+++ b/firmware/components/message-manager/src/message_manager.c
@@ -12,6 +12,34 @@
 static const char *TAG = "message_manager";
 static QueueHandle_t message_queue = NULL;
 
+// Observer Pattern: Listener-Liste
+#define MAX_MESSAGE_LISTENERS 8
+static message_listener_t message_listeners[MAX_MESSAGE_LISTENERS] = {0};
+static size_t message_listener_count = 0;
+
+void message_manager_register_listener(message_listener_t listener) {
+    if (listener && message_listener_count < MAX_MESSAGE_LISTENERS) {
+        // Doppelte Registrierung vermeiden
+        for (size_t i = 0; i < message_listener_count; ++i) {
+            if (message_listeners[i] == listener) return;
+        }
+        message_listeners[message_listener_count++] = listener;
+    }
+}
+
+void message_manager_unregister_listener(message_listener_t listener) {
+    for (size_t i = 0; i < message_listener_count; ++i) {
+        if (message_listeners[i] == listener) {
+            // Nachfolgende Listener nach vorne schieben
+            for (size_t j = i; j < message_listener_count - 1; ++j) {
+                message_listeners[j] = message_listeners[j + 1];
+            }
+            message_listeners[--message_listener_count] = NULL;
+            break;
+        }
+    }
+}
+
 static void message_manager_task(void *param)
 {
     message_t msg;
@@ -43,13 +71,6 @@ static void message_manager_task(void *param)
                     }
                     persistence_manager_deinit(&pm);
                     ESP_LOGI(TAG, "Setting written: %s", msg.data.settings.key);
-
-                    // Reagiere auf Änderung von light_active
-                    if (strcmp(msg.data.settings.key, "light_active") == 0)
-                    {
-                        extern void start_simulation(void);
-                        start_simulation();
-                    }
                 }
                 break;
             case MESSAGE_TYPE_BUTTON:
@@ -57,6 +78,12 @@ static void message_manager_task(void *param)
                 // TODO: Weiterverarbeitung/Callback für Button-Events
                 break;
             }
+            // Observer Pattern: Listener benachrichtigen
+            for (size_t i = 0; i < message_listener_count; ++i) {
+                if (message_listeners[i]) {
+                    message_listeners[i](&msg);
+                }
+            }
         }
     }
 }
diff --git a/firmware/main/app_task.cpp b/firmware/main/app_task.cpp
index 4ead0ce..59165c6 100644
--- a/firmware/main/app_task.cpp
+++ b/firmware/main/app_task.cpp
@@ -14,6 +14,7 @@
 #include "ui/ScreenSaver.h"
 #include "ui/SplashScreen.h"
 #include "wifi_manager.h"
+#include <cstring>
 #include <driver/i2c.h>
 #include <esp_diagnostics.h>
 #include <esp_insights.h>
@@ -127,6 +128,15 @@ static void init_ui(void)
     u8g2_SendBuffer(&u8g2);
 }
 
+static void on_message_received(const message_t *msg)
+{
+    if (msg && msg->type == MESSAGE_TYPE_SETTINGS && msg->data.settings.type == SETTINGS_TYPE_BOOL &&
+        std::strcmp(msg->data.settings.key, "light_active") == 0)
+    {
+        start_simulation();
+    }
+}
+
 static void handle_button(uint8_t button)
 {
     m_inactivityTracker->reset();
@@ -240,6 +250,8 @@ void app_task(void *args)
 
     wifi_manager_init();
 
+    message_manager_register_listener(on_message_received);
+
     start_simulation();
 
     auto oldTime = esp_timer_get_time();