yikes,

Hubs/Authenticated.cs

@@ -0,0 +1,36 @@
+using Microsoft.AspNetCore.SignalR;
+
+namespace Vanadium.Hubs
+{
+    public abstract class AuthenticatedHub : Hub
+    {
+        protected long PlayerId
+        {
+            get
+            {
+                var raw = Context.UserIdentifier;
+                if (raw == null || !long.TryParse(raw, out var id))
+                    throw new HubException("Unauthorized");
+                return id;
+            }
+        }
+
+        public override async Task OnConnectedAsync()
+        {
+            if (Context.UserIdentifier == null)
+            {
+                Context.Abort();
+                return;
+            }
+
+            await Groups.AddToGroupAsync(Context.ConnectionId, $"player:{PlayerId}");
+            await base.OnConnectedAsync();
+        }
+
+        public override async Task OnDisconnectedAsync(Exception? exception)
+        {
+            await Groups.RemoveFromGroupAsync(Context.ConnectionId, $"player:{PlayerId}");
+            await base.OnDisconnectedAsync(exception);
+        }
+    }
+}