Enforce GPU-only cluster participation

- Cluster clients now refuse to connect without GPU capabilities (CUDA/ROCm)
- Cluster master rejects authentication from clients without GPU backends
- Local master node only appears in cluster nodes list if GPU backends are available
- Master already prevented launching local worker processes without GPUs
- Systems without GPUs cannot participate in distributed processing
- Clear error messages when GPU requirements are not met
- Maintains cluster integrity by ensuring all nodes contribute computational power

vidai/cluster_client.py

@@ -54,6 +54,17 @@ class ClusterClient:
     async def connect(self) -> bool:
         """Connect to cluster master via secure websocket."""
         try:
+            # Detect available backends first
+            from .compat import detect_gpu_backends, get_available_backends
+            gpu_info = detect_gpu_backends()
+            available_backends = get_available_backends()
+
+            # Check if we have any GPU backends available
+            gpu_backends = [b for b in available_backends if b in ['cuda', 'rocm']]
+            if not gpu_backends:
+                print("No GPU backends detected (CUDA/ROCm). Cluster client requires GPU capabilities to connect.")
+                return False
+
             # Create SSL context that accepts self-signed certificates
             ssl_context = ssl.create_default_context()
             ssl_context.check_hostname = False
@@ -62,11 +73,6 @@ class ClusterClient:
             uri = f"wss://{self.host}:{self.port}/cluster"
             self.websocket = await websockets.connect(uri, ssl=ssl_context)
 
-            # Detect available backends
-            from .compat import detect_gpu_backends, get_available_backends
-            gpu_info = detect_gpu_backends()
-            available_backends = get_available_backends()
-
             # Get hostname
             import socket
             hostname = socket.gethostname()

vidai/cluster_master.py

@@ -186,7 +186,7 @@ class ClusterMaster:
 
         return {'type': 'error', 'message': 'Unknown message type'}
 
-    def _handle_auth(self, message: Dict[str, Any], client_sock: socket.socket) -> Dict[str, Any]:
+    def _handle_auth(self, message: Dict[str, Any], websocket: websockets.WebSocketServerProtocol) -> Dict[str, Any]:
         """Handle client authentication."""
         token = message.get('token')
         client_info = message.get('client_info', {})
@@ -194,6 +194,14 @@ class ClusterMaster:
         if not token:
             return {'type': 'auth_failed', 'message': 'No token provided'}
 
+        # Check if client has GPU capabilities
+        gpu_info = client_info.get('gpu_info', {})
+        available_backends = gpu_info.get('available_backends', [])
+        gpu_backends = [b for b in available_backends if b in ['cuda', 'rocm']]
+
+        if not gpu_backends:
+            return {'type': 'auth_failed', 'message': 'Client must have GPU capabilities (CUDA or ROCm) to join cluster'}
+
         # Generate client ID from token
         client_id = hashlib.sha256(token.encode()).hexdigest()[:16]
 
@@ -202,7 +210,7 @@ class ClusterMaster:
             'token': token,
             'info': client_info,
             'weight': client_info.get('weight', 100),
-            'gpu_info': client_info.get('gpu_info', {}),
+            'gpu_info': gpu_info,
             'connected_at': time.time(),
             'last_seen': time.time()
         }
@@ -214,7 +222,7 @@ class ClusterMaster:
             self.weight = 0
             print("First client connected - changing master weight to 0 (automatic)")
 
-        print(f"Client {client_id} authenticated")
+        print(f"Client {client_id} authenticated with GPU backends: {gpu_backends}")
         return {'type': 'auth_success', 'client_id': client_id}
 
     def _handle_register_processes(self, message: Dict[str, Any], websocket: websockets.WebSocketServerProtocol) -> Dict[str, Any]:

vidai/web.py

@@ -486,6 +486,10 @@ def api_cluster_nodes():
         nodes.append(node_data)
 
     # Detect and aggregate local worker processes on master
+    # Only show local node if GPU backends are available
+    from vidai.compat import get_available_backends
+    local_available_gpu_backends = [b for b in get_available_backends() if b in ['cuda', 'rocm']]
+    if local_available_gpu_backends:
         local_workers = detect_local_workers()
         if local_workers:
             # Group local workers by type
@@ -515,10 +519,6 @@ def api_cluster_nodes():
             # Use the longest uptime as representative
             max_uptime = max((w.get('uptime_seconds', 0) for w in local_workers), default=0)
 
-        # Get available GPU backends for local system
-        from vidai.compat import get_available_backends
-        local_available_gpu_backends = [b for b in get_available_backends() if b in ['cuda', 'rocm']]
-
             local_node = {
                 'token': 'local',
                 'token_name': 'Local Master Node',