yep

Shogi.UI/Pages/Home/GameBoard/GameBoard.razor

@@ -13,7 +13,7 @@
 }
 else if (isSpectating)
 {
-    <SpectatorGameBoard Session="session" OnRefetchSession="RefetchSession" />
+    <SpectatorGameBoard Session="session" />
 }
 else
 {
@@ -32,16 +32,25 @@ else
     protected override void OnInitialized()
     {
         base.OnInitialized();
-        ShogiSocket.OnPlayerMoved += OnPlayerMoved_RefetchSession;
-        ShogiSocket.OnSessionJoined += 
+        ShogiSocket.OnPlayerMoved += OnPlayerMoved_FetchSession;
+        ShogiSocket.OnSessionJoined += OnSessionJoined_FetchSession;
     }
 
     protected override async Task OnParametersSetAsync()
     {
-        await RefetchSession();
+        await FetchSession();
     }
 
-    async Task RefetchSession()
+    Task OnSessionJoined_FetchSession(SessionJoinedByPlayerSocketMessage args)
+    {
+        if (args.SessionName == SessionName)
+        {
+            return FetchSession();
+        }
+        return Task.CompletedTask;
+    }
+
+    async Task FetchSession()
     {
         if (!string.IsNullOrWhiteSpace(SessionName))
         {
@@ -59,11 +68,11 @@ else
         }
     }
 
-    Task OnPlayerMoved_RefetchSession(PlayerHasMovedMessage args)
+    Task OnPlayerMoved_FetchSession(PlayerHasMovedMessage args)
     {
         if (args.SessionName == SessionName)
         {
-            return RefetchSession();
+            return FetchSession();
         }
         return Task.CompletedTask;
     }