サーバーの技術負債を解消

src/Game.Realtime/Hubs/LobbyHub.cs

@@ -44,7 +44,7 @@ public async ValueTask ConnectAsync(string lobbyId, string playerName)
         _lobbyValidator.ValidateLobbyId(lobbyId);
         _lobbyValidator.ValidatePlayerName(playerName);
 
-        _userId = Context.CallContext.GetHttpContext().User!.GetUserId()!;
+        _userId = Context.CallContext.GetHttpContext().User.GetRequiredUserId();
         _playerName = playerName;
         _lobbyId = lobbyId;
 

src/Game.Realtime/Hubs/MatchmakingHub.cs

@@ -37,7 +37,7 @@ public async ValueTask SubscribeAsync(string gameMode)
     {
         _matchmakingValidator.ValidateGameMode(gameMode);
 
-        _userId = Context.CallContext.GetHttpContext().User!.GetUserId()!;
+        _userId = Context.CallContext.GetHttpContext().User.GetRequiredUserId();
         _gameMode = gameMode;
 
         var queueGroupName = $"matchmaking:{gameMode}";
@@ -53,7 +53,14 @@ await _subscriber.SubscribeAsync(channel, (_, message) =>
                 var result = JsonSerializer.Deserialize<MatchResult>(message.ToString());
                 if (result != null)
                 {
-                    Client.OnMatchFound(result);
+                    try
+                    {
+                        Client.OnMatchFound(result);
+                    }
+                    catch (Exception ex)
+                    {
+                        _logger.LogError(ex, "Failed to send match notification to user {UserId}", _userId);
+                    }
                 }
             }
             catch (Exception ex)
@@ -66,9 +73,16 @@ await _subscriber.SubscribeAsync(channel, (_, message) =>
         var queueChannel = RedisChannel.Literal($"matchmaking:queue:{gameMode}");
         await _subscriber.SubscribeAsync(queueChannel, (_, message) =>
         {
-            if (int.TryParse(message.ToString(), out var count))
+            try
+            {
+                if (int.TryParse(message.ToString(), out var count))
+                {
+                    Client.OnQueueStatusUpdated(count);
+                }
+            }
+            catch (Exception ex)
             {
-                Client.OnQueueStatusUpdated(count);
+                _logger.LogError(ex, "Failed to send queue status update to user {UserId}", _userId);
             }
         });
 

src/Game.Realtime/Services/MatchmakingProcessor.cs

@@ -81,6 +81,8 @@ private async Task ProcessGameModeAsync(string gameMode, int matchSize, Cancella
 
             if (queueCount < matchSize) break;
 
+            stoppingToken.ThrowIfCancellationRequested();
+
             var playerIds = await _queueService.DequeueTopPlayersAsync(gameMode, matchSize);
             if (playerIds.Length < matchSize)
             {

src/Game.Server.Shared/Extensions/ClaimsPrincipalExtensions.cs

@@ -10,4 +10,13 @@ public static class ClaimsPrincipalExtensions
         return principal?.FindFirst(JwtRegisteredClaimNames.Sub)?.Value
             ?? principal?.FindFirst(ClaimTypes.NameIdentifier)?.Value;
     }
+
+    /// <summary>
+    /// 認証フィルター通過後に使用する。userId が取得できない場合は InvalidOperationException をスローする。
+    /// </summary>
+    public static string GetRequiredUserId(this ClaimsPrincipal principal)
+    {
+        return principal.GetUserId()
+            ?? throw new InvalidOperationException("UserId claim not found. Ensure authentication filter has executed.");
+    }
 }

src/Game.Server/Middleware/RequestSigningMiddleware.cs

@@ -15,7 +15,7 @@
     private readonly byte[] _serverSecret;
     private readonly bool _enabled;
 
     private static readonly string[] ExemptPaths = new[]
     {
         "/api/auth/guest",
         "/api/auth/login",
@@ -107,8 +107,16 @@
         }
 
         // Nonce 重複チェック（Valkey）
-        var nonceAccepted = await TryAcceptNonce(context, nonce!);
-        if (!nonceAccepted)
+        var nonceResult = await TryAcceptNonce(context, nonce!);
+        if (nonceResult == NonceResult.Unavailable)
+        {
+            _logger.LogWarning("Nonce validation unavailable (Valkey down)");
+            context.Response.StatusCode = 503;
+            await context.Response.WriteAsJsonAsync(new { error = "SERVICE_UNAVAILABLE", message = "Service temporarily unavailable." });
+            return;
+        }
+
+        if (nonceResult == NonceResult.Replayed)
         {
             _logger.LogWarning("Nonce replay detected: {Nonce}", nonce.ToString());
             context.Response.StatusCode = 401;
@@ -158,16 +166,17 @@
         return ms.ToArray();
     }
 
-    private async Task<bool> TryAcceptNonce(HttpContext context, string nonce)
+    private enum NonceResult { Accepted, Replayed, Unavailable }
+
+    private async Task<NonceResult> TryAcceptNonce(HttpContext context, string nonce)
     {
         try
         {
             var redis = context.RequestServices.GetService<IConnectionMultiplexer>();
             if (redis == null || !redis.IsConnected)
             {
-                // Valkey 未接続時は署名検証のみで通過（Nonce チェックは省略）
-                _logger.LogWarning("Valkey not available, skipping nonce check");
-                return true;
+                _logger.LogWarning("Valkey not available, rejecting request for nonce validation");
+                return NonceResult.Unavailable;
             }
 
             var db = redis.GetDatabase();
@@ -176,12 +185,12 @@
                 TimeSpan.FromSeconds(RequestSigningConstants.NonceExpirySeconds),
                 When.NotExists);
 
-            return wasSet;
+            return wasSet ? NonceResult.Accepted : NonceResult.Replayed;
         }
         catch (RedisConnectionException ex)
         {
-            _logger.LogWarning(ex, "Valkey connection error during nonce check, allowing request");
-            return true;
+            _logger.LogWarning(ex, "Valkey connection error during nonce check, rejecting request");
+            return NonceResult.Unavailable;
         }
     }
 }

test/Game.Server.Tests/Integration/CustomWebApplicationFactory.cs

@@ -54,7 +54,10 @@ protected override void ConfigureWebHost(IWebHostBuilder builder)
             var mockDb = new Mock<IDatabase>();
             mockDb.Setup(d => d.PingAsync(It.IsAny<CommandFlags>()))
                 .ReturnsAsync(TimeSpan.FromMilliseconds(1));
+            // Nonce check の StringSetAsync が常に true を返すよう設定
+            mockDb.SetReturnsDefault(Task.FromResult(true));
             var mockRedis = new Mock<IConnectionMultiplexer>();
+            mockRedis.Setup(r => r.IsConnected).Returns(true);
             mockRedis.Setup(r => r.GetDatabase(It.IsAny<int>(), It.IsAny<object>()))
                 .Returns(mockDb.Object);
             services.RemoveAll<IConnectionMultiplexer>();