diff --git a/app/c2_main.py b/app/c2_main.py
index e8de0b0..5aad10e 100644
--- a/app/c2_main.py
+++ b/app/c2_main.py
@@ -118,12 +118,117 @@ mqtt_client = mqtt.Client(client_id=C2_ID)
 mqtt_client.on_connect = on_connect
 mqtt_client.on_message = on_message
 
+async def initialize_node_states():
+    """
+    On startup:
+    1. Mark all known nodes as 'unknown' until they check in.
+    2. Publish a discovery request to trigger immediate check-ins.
+    """
+    print("Initializing node states...")
+    try:
+        nodes_ref = db.collection("nodes")
+        
+        # Fetch all nodes (blocking call wrapped)
+        def get_all_nodes():
+            return list(nodes_ref.stream())
+        
+        docs = await async_firestore(get_all_nodes)
+        
+        batch = db.batch()
+        count = 0
+        
+        for doc in docs:
+            doc_ref = nodes_ref.document(doc.id)
+            batch.update(doc_ref, {"status": "unknown"})
+            count += 1
+            
+            # Update local cache if present
+            if doc.id in ACTIVE_NODES_CACHE:
+                ACTIVE_NODES_CACHE[doc.id]["status"] = "unknown"
+        
+        if count > 0:
+            await async_firestore(batch.commit)
+            print(f"Reset {count} nodes to 'unknown' status.")
+            
+        # Publish discovery request
+        print("Publishing discovery request...")
+        mqtt_client.publish("nodes/discovery/request", json.dumps({"ts": datetime.utcnow().isoformat()}), qos=1)
+        
+    except Exception as e:
+        print(f"Error initializing nodes: {e}")
+        traceback.print_exc()
+
+async def node_sweeper():
+    """
+    Background task to check for stale nodes.
+    Runs every 60 seconds.
+    Marks nodes as 'offline' if last_seen > 90 seconds ago.
+    """
+    print("Starting Node Sweeper...")
+    while True:
+        await asyncio.sleep(60)
+        try:
+            nodes_ref = db.collection("nodes")
+            
+            def get_all_nodes():
+                return list(nodes_ref.stream())
+            
+            docs = await async_firestore(get_all_nodes)
+            
+            batch = db.batch()
+            updates_count = 0
+            now = datetime.utcnow()
+            
+            for doc in docs:
+                data = doc.to_dict()
+                node_id = doc.id
+                status = data.get("status")
+                last_seen = data.get("last_seen")
+                
+                # Skip if already offline
+                if status == "offline":
+                    continue
+                
+                is_stale = False
+                if last_seen:
+                    # Handle timezone awareness (Firestore returns aware, utcnow is naive)
+                    if last_seen.tzinfo:
+                        last_seen = last_seen.replace(tzinfo=None)
+                    
+                    delta = (now - last_seen).total_seconds()
+                    if delta > 90:
+                        is_stale = True
+                else:
+                    # No timestamp? Treat as stale if not offline
+                    is_stale = True
+                
+                if is_stale:
+                    print(f"Node {node_id} is stale. Marking offline.")
+                    doc_ref = nodes_ref.document(node_id)
+                    batch.update(doc_ref, {"status": "offline", "radio_state": "unknown"})
+                    updates_count += 1
+                    
+                    if node_id in ACTIVE_NODES_CACHE:
+                        ACTIVE_NODES_CACHE[node_id]["status"] = "offline"
+            
+            if updates_count > 0:
+                await async_firestore(batch.commit)
+                print(f"Sweeper marked {updates_count} nodes as offline.")
+                
+        except Exception as e:
+            print(f"Error in node sweeper: {e}")
+            traceback.print_exc()
+
 @app.on_event("startup")
 async def startup_event():
     global MAIN_LOOP
     MAIN_LOOP = asyncio.get_running_loop()
     mqtt_client.connect_async(MQTT_BROKER, 1883, 60)
     mqtt_client.loop_start()
+    
+    # Start background tasks
+    asyncio.create_task(initialize_node_states())
+    asyncio.create_task(node_sweeper())
 
 @app.get("/nodes")
 async def get_nodes():
diff --git a/docker-compose.yml b/docker-compose.yml
index 0e8031c..13a6d4f 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -9,28 +9,11 @@ services:
       - FIRESTORE_DB_ID=${FIRESTORE_DB_ID:-c2-server}
       - MQTT_BROKER=mqtt-broker
       - PORT=8000
-    depends_on:
-      - mqtt-broker
     ports:
       - "8000:8000"
     networks:
       - radio-shared-net
 
-  # The Post Office (MQTT Broker)
-  mqtt-broker:
-    image: eclipse-mosquitto:latest
-    container_name: radio-mqtt
-    restart: always
-    ports:
-      - "1883:1883"
-      - "9001:9001"
-    volumes:
-      - ./mosquitto/config/:/mosquitto/config/
-      - ./mosquitto/data/:/mosquitto/data/
-      - ./mosquitto/log/:/mosquitto/log/
-    networks:
-      - radio-shared-net
-
 networks:
   radio-shared-net:
     external: true
\ No newline at end of file
diff --git a/mqtt-compose.yml b/mqtt-compose.yml
new file mode 100644
index 0000000..c3808ce
--- /dev/null
+++ b/mqtt-compose.yml
@@ -0,0 +1,19 @@
+services:
+# The Post Office (MQTT Broker)
+  mqtt-broker:
+    image: eclipse-mosquitto:latest
+    container_name: radio-mqtt
+    restart: always
+    ports:
+      - "1883:1883"
+      - "9001:9001"
+    volumes:
+      - ./mosquitto/config/:/mosquitto/config/
+      - ./mosquitto/data/:/mosquitto/data/
+      - ./mosquitto/log/:/mosquitto/log/
+    networks:
+      - radio-shared-net
+
+networks:
+  radio-shared-net:
+    external: true
\ No newline at end of file