Drain send queue on disconnect and ensure session cleanup

Maple2.Server.Core/Network/Session.cs

@@ -52,6 +52,7 @@ public abstract class Session : IDisposable {
 
     // Send queue for non-blocking sends
     private readonly BlockingCollection<(byte[] packet, int length)> sendQueue = new(new ConcurrentQueue<(byte[], int)>());
+    private Thread sendWorkerThread = null!;
 
     public long AccountId { get; protected set; }
     public long CharacterId { get; protected set; }
@@ -85,11 +86,11 @@ protected Session(TcpClient tcpClient) {
         recvCipher = new MapleCipher.Decryptor(VERSION, riv, BLOCK_IV);
 
         // Start send worker thread
-        var sendWorkerThread1 = new Thread(SendWorker) {
+        sendWorkerThread = new Thread(SendWorker) {
             Name = $"SendWorker-{name}",
             IsBackground = true,
         };
-        sendWorkerThread1.Start();
+        sendWorkerThread.Start();
     }
 
     ~Session() => Dispose(false);
@@ -133,6 +134,14 @@ public void Disconnect([CallerMemberName] string caller = "", [CallerLineNumber]
 
         if (Interlocked.Exchange(ref disconnecting, 1) == 1) return;
         Logger.Information("Disconnected {Session} at {Caller} in {FilePath} on line {LineNumber}", this, caller, filePath, line);
+
+        // Drain the send queue before disposing — ensures queued packets (e.g. migration)
+        // are delivered to the client before the connection is closed.
+        try { sendQueue.CompleteAdding(); } catch (ObjectDisposedException) { }
+        try { sendWorkerThread.Join(STOP_TIMEOUT); } catch (Exception ex) {
+            Logger.Debug(ex, "SendWorker drain join failed");
+        }
+
         Dispose();
     }
 
@@ -320,7 +329,7 @@ private void SendInternal(byte[] packet, int length) {
     }
 
     private void SendRaw(ByteWriter packet) {
-        if (disposed || disconnecting == 1) return;
+        if (disposed) return;
 
         try {
             // Use async write with timeout to prevent indefinite blocking
@@ -359,12 +368,12 @@ private void SendRaw(ByteWriter packet) {
     private void SendWorker() {
         try {
             foreach ((byte[] packet, int length) in sendQueue.GetConsumingEnumerable()) {
-                if (disposed || disconnecting == 1) break;
+                if (disposed) break;
 
                 // Encrypt outside lock, then send with timeout
                 PoolByteWriter encryptedPacket;
                 lock (sendCipher) {
-                    if (disposed || disconnecting == 1) break;
+                    if (disposed) break;
                     encryptedPacket = sendCipher.Encrypt(packet, 0, length);
                 }
                 try {

Maple2.Server.Game/Manager/DungeonManager.cs

@@ -609,6 +609,7 @@ private void MigrateToDungeon() {
         } catch (RpcException ex) {
             session.Send(MigrationPacket.GameToGameError(MigrationError.s_move_err_default));
             session.Send(NoticePacket.Disconnect(new InterfaceText(ex.Message)));
+        } finally {
             session.Disconnect();
         }
     }

Maple2.Server.Game/PacketHandlers/ChannelHandler.cs

@@ -38,7 +38,6 @@ public override void Handle(GameSession session, IByteReader packet) {
             var endpoint = new IPEndPoint(IPAddress.Parse(response.IpAddress), response.Port);
             session.Send(MigrationPacket.GameToGame(endpoint, response.Token, session.Field?.MapId ?? 0));
             session.State = SessionState.ChangeChannel;
-            session.Disconnect();
         } catch (RpcException ex) {
             Logger.Error(ex, "Failed to migrate to channel {Channel}", channel);
 
@@ -47,6 +46,8 @@ public override void Handle(GameSession session, IByteReader packet) {
             // Update the client with the latest channel list.
             ChannelsResponse response = World.Channels(new ChannelsRequest());
             session.Send(ChannelPacket.Load(response.Channels));
+        } finally {
+            session.Disconnect();
         }
     }
 }

Maple2.Server.Game/PacketHandlers/QuitHandler.cs

@@ -46,15 +46,11 @@ public override void Handle(GameSession session, IByteReader packet) {
             MigrateOutResponse response = World.MigrateOut(request);
             var endpoint = new IPEndPoint(IPAddress.Parse(response.IpAddress), response.Port);
             session.Send(MigrationPacket.GameToLogin(endpoint, response.Token));
-            // Do NOT disconnect here — let the client close the TCP connection after
-            // receiving the migration packet. Calling Disconnect() immediately would
-            // set disconnecting=1, causing SendWorker to drop the queued packet.
-            // The natural TCP close will trigger the full Dispose chain (leave field,
-            // update PlayerInfo, save state, etc.).
         } catch (RpcException ex) {
             Logger.Error(ex, "MigrateOut failed for account={AccountId} char={CharacterId}",
                 session.AccountId, session.CharacterId);
             session.Send(MigrationPacket.GameToLoginError(s_move_err_default));
+        } finally {
             session.Disconnect();
         }
     }

Maple2.Server.Game/Session/GameSession.cs

@@ -702,6 +702,7 @@ public void Migrate(int mapId, long ownerId = 0) {
         } catch (RpcException ex) {
             Send(MigrationPacket.GameToGameError(MigrationError.s_move_err_default));
             Send(NoticePacket.Disconnect(new InterfaceText(ex.Message)));
+        } finally {
             Disconnect();
         }
     }

Maple2.Server.Login/PacketHandlers/CharacterManagementHandler.cs

@@ -96,6 +96,7 @@ private void HandleSelect(LoginSession session, IByteReader packet) {
             MigrateOutResponse response = World.MigrateOut(request);
             var endpoint = new IPEndPoint(IPAddress.Parse(response.IpAddress), response.Port);
             session.Send(MigrationPacket.LoginToGame(endpoint, response.Token, character.MapId));
+            session.Disconnect();
         } catch (RpcException ex) when (ex.StatusCode == StatusCode.Unavailable) {
             session.Send(MigrationPacket.LoginToGameError(s_move_err_no_server, ex.Message));
         } catch (RpcException ex) when (ex.StatusCode == StatusCode.ResourceExhausted) {

Maple2.Server.Tests/Tools/EventQueueTests.cs

@@ -62,8 +62,13 @@ public void ScheduleRepeated_SkipFirst_SkipsInitialExecution() {
         queue.ScheduleRepeated(() => count++, TimeSpan.FromMilliseconds(20), skipFirst: true);
         queue.InvokeAll();
         Assert.That(count, Is.EqualTo(0));
-        Thread.Sleep(25);
-        queue.InvokeAll();
+
+        // Wait with retry to handle timing imprecision on CI environments
+        int maxRetries = 10;
+        for (int i = 0; i < maxRetries && count == 0; i++) {
+            Thread.Sleep(10);
+            queue.InvokeAll();
+        }
         Assert.That(count, Is.EqualTo(1));
     }
 }