From 6e759008dda649c4e9c7ea64a75173bc916b845a Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 13:30:48 +0900
Subject: [PATCH 1/7] Abstract connection management and add serial port
 support

---
 .../ConnectionManagerBase.cs                  | 147 ++++++++++++++
 .../WelsonJS.Launcher/SerialPortManager.cs    | 183 ++++++++++++++++++
 .../WelsonJS.Launcher/WebSocketManager.cs     | 135 ++++++-------
 .../WelsonJS.Launcher.csproj                  |   3 +
 4 files changed, 392 insertions(+), 76 deletions(-)
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
new file mode 100644
index 0000000..68fb8c2
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
@@ -0,0 +1,147 @@
+// ConnectionManagerBase.cs
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2025 Catswords OSS and WelsonJS Contributors
+// https://github.com/gnh1201/welsonjs
+//
+using System;
+using System.Collections.Concurrent;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace WelsonJS.Launcher
+{
+    /// <summary>
+    /// Provides a reusable pattern for keeping long-lived connections alive and
+    /// recreating them transparently when the underlying connection becomes invalid.
+    /// </summary>
+    /// <typeparam name="TParameters">A descriptor used to create a unique key for each connection.</typeparam>
+    /// <typeparam name="TConnection">The concrete connection type.</typeparam>
+    public abstract class ConnectionManagerBase<TParameters, TConnection>
+        where TConnection : class
+    {
+        private readonly ConcurrentDictionary<string, TConnection> _pool = new ConcurrentDictionary<string, TConnection>();
+
+        /// <summary>
+        /// Creates a unique cache key for the given connection parameters.
+        /// </summary>
+        protected abstract string CreateKey(TParameters parameters);
+
+        /// <summary>
+        /// Establishes a new connection using the provided parameters.
+        /// </summary>
+        protected abstract Task<TConnection> OpenConnectionAsync(TParameters parameters, CancellationToken token);
+
+        /// <summary>
+        /// Validates whether the existing connection is still usable.
+        /// </summary>
+        protected abstract bool IsConnectionValid(TConnection connection);
+
+        /// <summary>
+        /// Releases the resources associated with a connection instance.
+        /// </summary>
+        protected virtual void CloseConnection(TConnection connection)
+        {
+            if (connection is IDisposable disposable)
+            {
+                disposable.Dispose();
+            }
+        }
+
+        /// <summary>
+        /// Retrieves a cached connection or creates a new one if needed.
+        /// </summary>
+        protected async Task<TConnection> GetOrCreateAsync(TParameters parameters, CancellationToken token)
+        {
+            string key = CreateKey(parameters);
+
+            if (_pool.TryGetValue(key, out var existing) && IsConnectionValid(existing))
+            {
+                return existing;
+            }
+
+            RemoveInternal(key, existing);
+
+            var connection = await OpenConnectionAsync(parameters, token).ConfigureAwait(false);
+            _pool[key] = connection;
+            return connection;
+        }
+
+        /// <summary>
+        /// Removes the connection associated with the provided parameters.
+        /// </summary>
+        public void Remove(TParameters parameters)
+        {
+            string key = CreateKey(parameters);
+            if (_pool.TryRemove(key, out var connection))
+            {
+                CloseSafely(connection);
+            }
+        }
+
+        /// <summary>
+        /// Executes an action against the managed connection, retrying once if the first attempt fails.
+        /// </summary>
+        protected async Task<TResult> ExecuteWithRetryAsync<TResult>(
+            TParameters parameters,
+            Func<TConnection, CancellationToken, Task<TResult>> operation,
+            int maxAttempts,
+            CancellationToken token)
+        {
+            if (operation == null) throw new ArgumentNullException(nameof(operation));
+            if (maxAttempts < 1) throw new ArgumentOutOfRangeException(nameof(maxAttempts));
+
+            Exception lastError = null;
+
+            for (int attempt = 0; attempt < maxAttempts; attempt++)
+            {
+                token.ThrowIfCancellationRequested();
+                var connection = await GetOrCreateAsync(parameters, token).ConfigureAwait(false);
+
+                try
+                {
+                    return await operation(connection, token).ConfigureAwait(false);
+                }
+                catch (OperationCanceledException)
+                {
+                    throw;
+                }
+                catch (Exception ex)
+                {
+                    lastError = ex;
+                    Remove(parameters);
+                    if (attempt == maxAttempts - 1)
+                    {
+                        throw;
+                    }
+                }
+            }
+
+            throw lastError ?? new InvalidOperationException("Unreachable state in ExecuteWithRetryAsync");
+        }
+
+        private void RemoveInternal(string key, TConnection connection)
+        {
+            if (!string.IsNullOrEmpty(key))
+            {
+                _pool.TryRemove(key, out _);
+            }
+
+            if (connection != null)
+            {
+                CloseSafely(connection);
+            }
+        }
+
+        private void CloseSafely(TConnection connection)
+        {
+            try
+            {
+                CloseConnection(connection);
+            }
+            catch
+            {
+                // Ignore dispose exceptions.
+            }
+        }
+    }
+}
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
new file mode 100644
index 0000000..82d2fa3
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
@@ -0,0 +1,183 @@
+// SerialPortManager.cs
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2025 Catswords OSS and WelsonJS Contributors
+// https://github.com/gnh1201/welsonjs
+//
+using System;
+using System.IO;
+using System.IO.Ports;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace WelsonJS.Launcher
+{
+    public sealed class SerialPortManager : ConnectionManagerBase<SerialPortManager.ConnectionParameters, SerialPort>
+    {
+        public struct ConnectionParameters
+        {
+            public ConnectionParameters(
+                string portName,
+                int baudRate,
+                Parity parity = Parity.None,
+                int dataBits = 8,
+                StopBits stopBits = StopBits.One,
+                Handshake handshake = Handshake.None,
+                int readTimeout = 500,
+                int writeTimeout = 500,
+                int readBufferSize = 1024)
+            {
+                if (string.IsNullOrWhiteSpace(portName)) throw new ArgumentNullException(nameof(portName));
+
+                PortName = portName;
+                BaudRate = baudRate;
+                Parity = parity;
+                DataBits = dataBits;
+                StopBits = stopBits;
+                Handshake = handshake;
+                ReadTimeout = readTimeout;
+                WriteTimeout = writeTimeout;
+                ReadBufferSize = readBufferSize > 0 ? readBufferSize : 1024;
+            }
+
+            public string PortName { get; }
+            public int BaudRate { get; }
+            public Parity Parity { get; }
+            public int DataBits { get; }
+            public StopBits StopBits { get; }
+            public Handshake Handshake { get; }
+            public int ReadTimeout { get; }
+            public int WriteTimeout { get; }
+            public int ReadBufferSize { get; }
+        }
+
+        protected override string CreateKey(ConnectionParameters parameters)
+        {
+            return string.Join(",", new object[]
+            {
+                parameters.PortName.ToUpperInvariant(),
+                parameters.BaudRate,
+                parameters.Parity,
+                parameters.DataBits,
+                parameters.StopBits,
+                parameters.Handshake
+            });
+        }
+
+        protected override Task<SerialPort> OpenConnectionAsync(ConnectionParameters parameters, CancellationToken token)
+        {
+            token.ThrowIfCancellationRequested();
+
+            var port = new SerialPort(parameters.PortName, parameters.BaudRate, parameters.Parity, parameters.DataBits, parameters.StopBits)
+            {
+                Handshake = parameters.Handshake,
+                ReadTimeout = parameters.ReadTimeout,
+                WriteTimeout = parameters.WriteTimeout
+            };
+
+            try
+            {
+                port.Open();
+                return Task.FromResult(port);
+            }
+            catch
+            {
+                port.Dispose();
+                throw;
+            }
+        }
+
+        protected override bool IsConnectionValid(SerialPort connection)
+        {
+            return connection != null && connection.IsOpen;
+        }
+
+        protected override void CloseConnection(SerialPort connection)
+        {
+            try
+            {
+                if (connection != null && connection.IsOpen)
+                {
+                    connection.Close();
+                }
+            }
+            finally
+            {
+                connection?.Dispose();
+            }
+        }
+
+        public Task<TResult> ExecuteAsync<TResult>(
+            ConnectionParameters parameters,
+            Func<SerialPort, CancellationToken, Task<TResult>> operation,
+            int maxAttempts = 2,
+            CancellationToken cancellationToken = default)
+        {
+            if (operation == null) throw new ArgumentNullException(nameof(operation));
+            return ExecuteWithRetryAsync(parameters, operation, maxAttempts, cancellationToken);
+        }
+
+        public async Task<string> SendAndReceiveAsync(
+            ConnectionParameters parameters,
+            string message,
+            Encoding encoding,
+            CancellationToken cancellationToken = default)
+        {
+            if (encoding == null) throw new ArgumentNullException(nameof(encoding));
+            byte[] payload = encoding.GetBytes(message ?? string.Empty);
+
+            return await ExecuteWithRetryAsync(
+                parameters,
+                (port, token) => SendAndReceiveInternalAsync(port, parameters.ReadBufferSize, payload, encoding, token),
+                2,
+                cancellationToken).ConfigureAwait(false);
+        }
+
+        private static async Task<string> SendAndReceiveInternalAsync(
+            SerialPort port,
+            int bufferSize,
+            byte[] payload,
+            Encoding encoding,
+            CancellationToken token)
+        {
+            port.DiscardInBuffer();
+            port.DiscardOutBuffer();
+
+            if (payload.Length > 0)
+            {
+                await Task.Run(() => port.Write(payload, 0, payload.Length), token).ConfigureAwait(false);
+            }
+
+            using (var stream = new MemoryStream())
+            {
+                var buffer = new byte[bufferSize];
+
+                while (true)
+                {
+                    try
+                    {
+                        int read = await Task.Run(() => port.Read(buffer, 0, buffer.Length), token).ConfigureAwait(false);
+                        if (read > 0)
+                        {
+                            stream.Write(buffer, 0, read);
+                            if (read < buffer.Length)
+                            {
+                                break;
+                            }
+                        }
+                        else
+                        {
+                            break;
+                        }
+                    }
+                    catch (TimeoutException)
+                    {
+                        break;
+                    }
+                }
+
+                return encoding.GetString(stream.ToArray());
+            }
+        }
+    }
+}
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs
index 4d953c3..f34ebcb 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs
@@ -4,7 +4,6 @@
 // https://github.com/gnh1201/welsonjs
 // 
 using System;
-using System.Collections.Concurrent;
 using System.Net.WebSockets;
 using System.Security.Cryptography;
 using System.Text;
@@ -13,86 +12,73 @@ using System.Threading.Tasks;
 
 namespace WelsonJS.Launcher
 {
-    public class WebSocketManager
+    public sealed class WebSocketManager : ConnectionManagerBase<WebSocketManager.Endpoint, ClientWebSocket>
     {
-        private class Entry
+        public struct Endpoint
         {
-            public ClientWebSocket Socket;
-            public string Host;
-            public int Port;
-            public string Path;
+            public Endpoint(string host, int port, string path)
+            {
+                Host = host ?? throw new ArgumentNullException(nameof(host));
+                Port = port;
+                Path = path ?? string.Empty;
+            }
+
+            public string Host { get; }
+            public int Port { get; }
+            public string Path { get; }
         }
 
-        private readonly ConcurrentDictionary<string, Entry> _pool = new ConcurrentDictionary<string, Entry>();
-
-        // Create a unique cache key using MD5 hash
-        private string MakeKey(string host, int port, string path)
+        protected override string CreateKey(Endpoint parameters)
         {
-            string raw = host + ":" + port + "/" + path;
+            string raw = parameters.Host + ":" + parameters.Port + "/" + parameters.Path;
             using (var md5 = MD5.Create())
             {
                 byte[] hash = md5.ComputeHash(Encoding.UTF8.GetBytes(raw));
-                return BitConverter.ToString(hash).Replace("-", "").ToLower();
+                return BitConverter.ToString(hash).Replace("-", string.Empty).ToLowerInvariant();
             }
         }
 
-        // Get an open WebSocket or connect a new one
-        public async Task<ClientWebSocket> GetOrCreateAsync(string host, int port, string path)
+        protected override async Task<ClientWebSocket> OpenConnectionAsync(Endpoint parameters, CancellationToken token)
         {
-            string key = MakeKey(host, port, path);
-
-            if (_pool.TryGetValue(key, out var entry))
-            {
-                var sock = entry.Socket;
-
-                if (sock == null || sock.State != WebSocketState.Open)
-                {
-                    Remove(host, port, path);
-                }
-                else
-                {
-                    return sock;
-                }
-            }
-
-            var newSock = new ClientWebSocket();
-            var uri = new Uri($"ws://{host}:{port}/{path}");
+            var socket = new ClientWebSocket();
+            var uri = new Uri($"ws://{parameters.Host}:{parameters.Port}/{parameters.Path}");
 
             try
             {
-                await newSock.ConnectAsync(uri, CancellationToken.None);
-
-                _pool[key] = new Entry
-                {
-                    Socket = newSock,
-                    Host = host,
-                    Port = port,
-                    Path = path
-                };
-
-                return newSock;
+                await socket.ConnectAsync(uri, token).ConfigureAwait(false);
+                return socket;
             }
             catch (Exception ex)
             {
-                newSock.Dispose();
-                Remove(host, port, path);
+                socket.Dispose();
                 throw new WebSocketException("WebSocket connection failed", ex);
             }
         }
 
-        // Remove a socket from the pool and dispose it
+        protected override bool IsConnectionValid(ClientWebSocket connection)
+        {
+            return connection != null && connection.State == WebSocketState.Open;
+        }
+
+        protected override void CloseConnection(ClientWebSocket connection)
+        {
+            try
+            {
+                connection?.Abort();
+            }
+            catch
+            {
+                // Ignore abort exceptions.
+            }
+            finally
+            {
+                connection?.Dispose();
+            }
+        }
+
         public void Remove(string host, int port, string path)
         {
-            string key = MakeKey(host, port, path);
-            if (_pool.TryRemove(key, out var entry))
-            {
-                try
-                {
-                    entry.Socket?.Abort();
-                    entry.Socket?.Dispose();
-                }
-                catch { /* Ignore dispose exceptions */ }
-            }
+            Remove(new Endpoint(host, port, path));
         }
 
         // Send and receive with automatic retry on first failure
@@ -103,35 +89,32 @@ namespace WelsonJS.Launcher
                 ? new CancellationTokenSource(TimeSpan.FromSeconds(timeoutSec))
                 : new CancellationTokenSource();
 
-            for (int attempt = 0; attempt < 2; attempt++)
+            try
             {
-                try
-                {
-                    return await TrySendAndReceiveAsync(host, port, path, buf, cts.Token);
-                }
-                catch
-                {
-                    Remove(host, port, path);
-                    if (attempt == 1) throw;
-                }
+                return await ExecuteWithRetryAsync(
+                    new Endpoint(host, port, path),
+                    (socket, token) => TrySendAndReceiveAsync(socket, buf, token),
+                    2,
+                    cts.Token).ConfigureAwait(false);
+            }
+            finally
+            {
+                cts.Dispose();
             }
-
-            throw new InvalidOperationException("Unreachable");
         }
 
         // Actual send and receive implementation that never truncates the accumulated data.
         // - Uses a fixed-size read buffer ONLY for I/O
         // - Accumulates dynamically into a List<byte[]> until EndOfMessage
-        private async Task<string> TrySendAndReceiveAsync(string host, int port, string path, byte[] buf, CancellationToken token)
+        private async Task<string> TrySendAndReceiveAsync(ClientWebSocket socket, byte[] buf, CancellationToken token)
         {
             try
             {
-                var sock = await GetOrCreateAsync(host, port, path);
-                if (sock.State != WebSocketState.Open)
+                if (socket.State != WebSocketState.Open)
                     throw new WebSocketException("WebSocket is not in an open state");
 
                 // Send request as a single text frame
-                await sock.SendAsync(new ArraySegment<byte>(buf), WebSocketMessageType.Text, true, token);
+                await socket.SendAsync(new ArraySegment<byte>(buf), WebSocketMessageType.Text, true, token).ConfigureAwait(false);
 
                 // Fixed-size read buffer for I/O (does NOT cap total message size)
                 byte[] readBuffer = new byte[8192];
@@ -142,12 +125,12 @@ namespace WelsonJS.Launcher
 
                 while (true)
                 {
-                    var res = await sock.ReceiveAsync(new ArraySegment<byte>(readBuffer), token);
+                    var res = await socket.ReceiveAsync(new ArraySegment<byte>(readBuffer), token).ConfigureAwait(false);
 
                     if (res.MessageType == WebSocketMessageType.Close)
                     {
-                        try { await sock.CloseAsync(WebSocketCloseStatus.NormalClosure, "Closing as requested by server", token); } catch { }
-                        throw new WebSocketException($"WebSocket closed by server: {sock.CloseStatus} {sock.CloseStatusDescription}");
+                        try { await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, "Closing as requested by server", token).ConfigureAwait(false); } catch { }
+                        throw new WebSocketException($"WebSocket closed by server: {socket.CloseStatus} {socket.CloseStatusDescription}");
                     }
 
                     if (res.Count > 0)
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj b/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj
index 5bc8b61..e1fc1f4 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj
@@ -80,6 +80,7 @@
     <Reference Include="System.Deployment" />
     <Reference Include="System.Drawing" />
     <Reference Include="System.IO.Compression.FileSystem" />
+    <Reference Include="System.IO.Ports" />
     <Reference Include="System.Net.Http" />
     <Reference Include="System.Web" />
     <Reference Include="System.Windows.Forms" />
@@ -87,6 +88,7 @@
     <Reference Include="System.Xml.Linq" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="ConnectionManagerBase.cs" />
     <Compile Include="ICompatibleLogger.cs" />
     <Compile Include="IResourceTool.cs" />
     <Compile Include="JsCore.cs" />
@@ -128,6 +130,7 @@
       <DependentUpon>GlobalSettingsForm.cs</DependentUpon>
     </Compile>
     <Compile Include="ResourceServer.cs" />
+    <Compile Include="SerialPortManager.cs" />
     <Compile Include="TraceLogger.cs" />
     <Compile Include="WebSocketManager.cs" />
     <EmbeddedResource Include="EnvForm.resx">

From b8362e570cc4d88187d9d2f865220d76b84b96ff Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 13:42:35 +0900
Subject: [PATCH 2/7] Add connection monitor for managed transports

---
 .../ConnectionManagerBase.cs                  |  98 ++++++++++++-
 .../ConnectionMonitorForm.Designer.cs         | 132 +++++++++++++++++
 .../ConnectionMonitorForm.cs                  | 137 ++++++++++++++++++
 .../ConnectionMonitorForm.resx                | 120 +++++++++++++++
 .../ConnectionMonitorRegistry.cs              |  56 +++++++
 .../IManagedConnectionProvider.cs             |  30 ++++
 .../WelsonJS.Launcher/MainForm.Designer.cs    |  10 ++
 .../WelsonJS.Launcher/MainForm.cs             |  12 ++
 .../ManagedConnectionStatus.cs                |  32 ++++
 .../WelsonJS.Launcher/SerialPortManager.cs    |  48 +++++-
 .../WelsonJS.Launcher/WebSocketManager.cs     |  48 +++++-
 .../WelsonJS.Launcher.csproj                  |  12 ++
 12 files changed, 726 insertions(+), 9 deletions(-)
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.Designer.cs
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.cs
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.resx
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorRegistry.cs
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/IManagedConnectionProvider.cs
 create mode 100644 WelsonJS.Toolkit/WelsonJS.Launcher/ManagedConnectionStatus.cs

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
index 68fb8c2..9bf436f 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
@@ -5,6 +5,7 @@
 //
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -19,7 +20,8 @@ namespace WelsonJS.Launcher
     public abstract class ConnectionManagerBase<TParameters, TConnection>
         where TConnection : class
     {
-        private readonly ConcurrentDictionary<string, TConnection> _pool = new ConcurrentDictionary<string, TConnection>();
+        private readonly ConcurrentDictionary<string, (TConnection Connection, TParameters Parameters)> _pool
+            = new ConcurrentDictionary<string, (TConnection, TParameters)>();
 
         /// <summary>
         /// Creates a unique cache key for the given connection parameters.
@@ -54,15 +56,15 @@ namespace WelsonJS.Launcher
         {
             string key = CreateKey(parameters);
 
-            if (_pool.TryGetValue(key, out var existing) && IsConnectionValid(existing))
+            if (_pool.TryGetValue(key, out var existing) && IsConnectionHealthy(existing.Connection))
             {
-                return existing;
+                return existing.Connection;
             }
 
-            RemoveInternal(key, existing);
+            RemoveInternal(key, existing.Connection);
 
             var connection = await OpenConnectionAsync(parameters, token).ConfigureAwait(false);
-            _pool[key] = connection;
+            _pool[key] = (connection, parameters);
             return connection;
         }
 
@@ -72,12 +74,55 @@ namespace WelsonJS.Launcher
         public void Remove(TParameters parameters)
         {
             string key = CreateKey(parameters);
-            if (_pool.TryRemove(key, out var connection))
+            if (_pool.TryRemove(key, out var entry))
             {
-                CloseSafely(connection);
+                CloseSafely(entry.Connection);
             }
         }
 
+        /// <summary>
+        /// Removes the connection associated with the provided cache key.
+        /// </summary>
+        protected bool TryRemoveByKey(string key)
+        {
+            if (string.IsNullOrEmpty(key))
+            {
+                return false;
+            }
+
+            if (_pool.TryRemove(key, out var entry))
+            {
+                CloseSafely(entry.Connection);
+                return true;
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Provides a snapshot of the currently tracked connections.
+        /// </summary>
+        protected IReadOnlyList<ConnectionSnapshot> SnapshotConnections()
+        {
+            var entries = _pool.ToArray();
+            var result = new ConnectionSnapshot[entries.Length];
+
+            for (int i = 0; i < entries.Length; i++)
+            {
+                var entry = entries[i];
+                var connection = entry.Value.Connection;
+                bool isValid = IsConnectionHealthy(connection);
+
+                result[i] = new ConnectionSnapshot(
+                    entry.Key,
+                    entry.Value.Parameters,
+                    connection,
+                    isValid);
+            }
+
+            return result;
+        }
+
         /// <summary>
         /// Executes an action against the managed connection, retrying once if the first attempt fails.
         /// </summary>
@@ -119,6 +164,23 @@ namespace WelsonJS.Launcher
             throw lastError ?? new InvalidOperationException("Unreachable state in ExecuteWithRetryAsync");
         }
 
+        private bool IsConnectionHealthy(TConnection connection)
+        {
+            if (connection == null)
+            {
+                return false;
+            }
+
+            try
+            {
+                return IsConnectionValid(connection);
+            }
+            catch
+            {
+                return false;
+            }
+        }
+
         private void RemoveInternal(string key, TConnection connection)
         {
             if (!string.IsNullOrEmpty(key))
@@ -143,5 +205,27 @@ namespace WelsonJS.Launcher
                 // Ignore dispose exceptions.
             }
         }
+
+        /// <summary>
+        /// Represents an immutable snapshot of a managed connection.
+        /// </summary>
+        protected readonly struct ConnectionSnapshot
+        {
+            public ConnectionSnapshot(string key, TParameters parameters, TConnection connection, bool isValid)
+            {
+                Key = key;
+                Parameters = parameters;
+                Connection = connection;
+                IsValid = isValid;
+            }
+
+            public string Key { get; }
+
+            public TParameters Parameters { get; }
+
+            public TConnection Connection { get; }
+
+            public bool IsValid { get; }
+        }
     }
 }
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.Designer.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.Designer.cs
new file mode 100644
index 0000000..a555de8
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.Designer.cs
@@ -0,0 +1,132 @@
+namespace WelsonJS.Launcher
+{
+    partial class ConnectionMonitorForm
+    {
+        /// <summary>
+        /// Required designer variable.
+        /// </summary>
+        private System.ComponentModel.IContainer components = null;
+
+        /// <summary>
+        /// Clean up any resources being used.
+        /// </summary>
+        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing && (components != null))
+            {
+                components.Dispose();
+            }
+            base.Dispose(disposing);
+        }
+
+        #region Windows Form Designer generated code
+
+        private void InitializeComponent()
+        {
+            this.lvConnections = new System.Windows.Forms.ListView();
+            this.chType = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
+            this.chKey = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
+            this.chState = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
+            this.chDetails = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
+            this.chHealth = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
+            this.btnRefresh = new System.Windows.Forms.Button();
+            this.btnCloseSelected = new System.Windows.Forms.Button();
+            this.SuspendLayout();
+            // 
+            // lvConnections
+            // 
+            this.lvConnections.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
+            this.chType,
+            this.chKey,
+            this.chState,
+            this.chDetails,
+            this.chHealth});
+            this.lvConnections.FullRowSelect = true;
+            this.lvConnections.HideSelection = false;
+            this.lvConnections.Location = new System.Drawing.Point(12, 12);
+            this.lvConnections.MultiSelect = true;
+            this.lvConnections.Name = "lvConnections";
+            this.lvConnections.Size = new System.Drawing.Size(640, 260);
+            this.lvConnections.TabIndex = 0;
+            this.lvConnections.UseCompatibleStateImageBehavior = false;
+            this.lvConnections.View = System.Windows.Forms.View.Details;
+            this.lvConnections.SelectedIndexChanged += new System.EventHandler(this.lvConnections_SelectedIndexChanged);
+            // 
+            // chType
+            // 
+            this.chType.Text = "Type";
+            this.chType.Width = 100;
+            // 
+            // chKey
+            // 
+            this.chKey.Text = "Key";
+            this.chKey.Width = 140;
+            // 
+            // chState
+            // 
+            this.chState.Text = "State";
+            this.chState.Width = 100;
+            // 
+            // chDetails
+            // 
+            this.chDetails.Text = "Details";
+            this.chDetails.Width = 220;
+            // 
+            // chHealth
+            // 
+            this.chHealth.Text = "Health";
+            this.chHealth.Width = 80;
+            // 
+            // btnRefresh
+            // 
+            this.btnRefresh.Location = new System.Drawing.Point(12, 280);
+            this.btnRefresh.Name = "btnRefresh";
+            this.btnRefresh.Size = new System.Drawing.Size(95, 30);
+            this.btnRefresh.TabIndex = 1;
+            this.btnRefresh.Text = "Refresh";
+            this.btnRefresh.UseVisualStyleBackColor = true;
+            this.btnRefresh.Click += new System.EventHandler(this.btnRefresh_Click);
+            // 
+            // btnCloseSelected
+            // 
+            this.btnCloseSelected.Enabled = false;
+            this.btnCloseSelected.Location = new System.Drawing.Point(557, 280);
+            this.btnCloseSelected.Name = "btnCloseSelected";
+            this.btnCloseSelected.Size = new System.Drawing.Size(95, 30);
+            this.btnCloseSelected.TabIndex = 2;
+            this.btnCloseSelected.Text = "Close";
+            this.btnCloseSelected.UseVisualStyleBackColor = true;
+            this.btnCloseSelected.Click += new System.EventHandler(this.btnCloseSelected_Click);
+            // 
+            // ConnectionMonitorForm
+            // 
+            this.AutoScaleDimensions = new System.Drawing.SizeF(7F, 12F);
+            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
+            this.ClientSize = new System.Drawing.Size(664, 322);
+            this.Controls.Add(this.btnCloseSelected);
+            this.Controls.Add(this.btnRefresh);
+            this.Controls.Add(this.lvConnections);
+            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
+            this.Icon = global::WelsonJS.Launcher.Properties.Resources.favicon;
+            this.MaximizeBox = false;
+            this.MinimizeBox = false;
+            this.Name = "ConnectionMonitorForm";
+            this.Text = "Connection Monitor";
+            this.Load += new System.EventHandler(this.ConnectionMonitorForm_Load);
+            this.ResumeLayout(false);
+
+        }
+
+        #endregion
+
+        private System.Windows.Forms.ListView lvConnections;
+        private System.Windows.Forms.ColumnHeader chType;
+        private System.Windows.Forms.ColumnHeader chKey;
+        private System.Windows.Forms.ColumnHeader chState;
+        private System.Windows.Forms.ColumnHeader chDetails;
+        private System.Windows.Forms.ColumnHeader chHealth;
+        private System.Windows.Forms.Button btnRefresh;
+        private System.Windows.Forms.Button btnCloseSelected;
+    }
+}
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.cs
new file mode 100644
index 0000000..c7a9bbf
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.cs
@@ -0,0 +1,137 @@
+// ConnectionMonitorForm.cs
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2025 Catswords OSS and WelsonJS Contributors
+// https://github.com/gnh1201/welsonjs
+//
+using System;
+using System.Collections.Generic;
+using System.Windows.Forms;
+
+namespace WelsonJS.Launcher
+{
+    public partial class ConnectionMonitorForm : Form
+    {
+        public ConnectionMonitorForm()
+        {
+            InitializeComponent();
+        }
+
+        private void ConnectionMonitorForm_Load(object sender, EventArgs e)
+        {
+            RefreshConnections();
+        }
+
+        private void btnRefresh_Click(object sender, EventArgs e)
+        {
+            RefreshConnections();
+        }
+
+        private void lvConnections_SelectedIndexChanged(object sender, EventArgs e)
+        {
+            btnCloseSelected.Enabled = lvConnections.SelectedItems.Count > 0;
+        }
+
+        private void btnCloseSelected_Click(object sender, EventArgs e)
+        {
+            if (lvConnections.SelectedItems.Count == 0)
+            {
+                return;
+            }
+
+            var errors = new List<string>();
+            bool anyClosed = false;
+
+            foreach (ListViewItem item in lvConnections.SelectedItems)
+            {
+                if (item.Tag is ConnectionItemTag tag)
+                {
+                    try
+                    {
+                        if (tag.Provider.TryClose(tag.Key))
+                        {
+                            anyClosed = true;
+                        }
+                        else
+                        {
+                            errors.Add($"Unable to close {tag.Provider.ConnectionType} connection {tag.Key}.");
+                        }
+                    }
+                    catch (Exception ex)
+                    {
+                        errors.Add($"{tag.Provider.ConnectionType} {tag.Key}: {ex.Message}");
+                    }
+                }
+            }
+
+            if (anyClosed)
+            {
+                RefreshConnections();
+            }
+
+            if (errors.Count > 0)
+            {
+                MessageBox.Show(string.Join(Environment.NewLine, errors), "Connection Monitor", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+            }
+        }
+
+        private void RefreshConnections()
+        {
+            IReadOnlyList<IManagedConnectionProvider> providers = ConnectionMonitorRegistry.GetProviders();
+
+            lvConnections.BeginUpdate();
+            lvConnections.Items.Clear();
+
+            foreach (var provider in providers)
+            {
+                IReadOnlyCollection<ManagedConnectionStatus> statuses;
+                try
+                {
+                    statuses = provider.GetStatuses();
+                }
+                catch (Exception ex)
+                {
+                    var errorItem = new ListViewItem(provider.ConnectionType)
+                    {
+                        Tag = null
+                    };
+                    errorItem.SubItems.Add(string.Empty);
+                    errorItem.SubItems.Add("Error");
+                    errorItem.SubItems.Add(ex.Message);
+                    errorItem.SubItems.Add("Unknown");
+                    lvConnections.Items.Add(errorItem);
+                    continue;
+                }
+
+                foreach (var status in statuses)
+                {
+                    var item = new ListViewItem(status.ConnectionType)
+                    {
+                        Tag = new ConnectionItemTag(provider, status.Key)
+                    };
+                    item.SubItems.Add(status.Key);
+                    item.SubItems.Add(status.State);
+                    item.SubItems.Add(status.Description);
+                    item.SubItems.Add(status.IsValid ? "Healthy" : "Stale");
+                    lvConnections.Items.Add(item);
+                }
+            }
+
+            lvConnections.EndUpdate();
+
+            btnCloseSelected.Enabled = lvConnections.SelectedItems.Count > 0;
+        }
+
+        private sealed class ConnectionItemTag
+        {
+            public ConnectionItemTag(IManagedConnectionProvider provider, string key)
+            {
+                Provider = provider;
+                Key = key ?? string.Empty;
+            }
+
+            public IManagedConnectionProvider Provider { get; }
+
+            public string Key { get; }
+        }
+    }
+}
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.resx b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.resx
new file mode 100644
index 0000000..bdd5b01
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorForm.resx
@@ -0,0 +1,120 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!--
+    Microsoft ResX Schema
+
+    Version 2.0
+
+    The primary goals of this format is to allow a simple XML format
+    that is mostly human readable. The generation and parsing of the
+    various data types are done through the TypeConverter classes
+    associated with the data types.
+
+    Example:
+
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+
+    There are any number of "resheader" rows that contain simple
+    name/value pairs.
+
+    Each data row contains a name, and value. The row also contains a
+    type or mimetype. Type corresponds to a .NET class that support
+    text/value conversion through the TypeConverter architecture.
+    Classes that don't support this are serialized and stored with the
+    mimetype set.
+
+    The mimetype is used for serialized objects, and tells the
+    ResXResourceReader how to depersist the object. This is currently not
+    extensible. For a given mimetype the value must be set accordingly:
+
+    Note - application/x-microsoft.net.object.binary.base64 is the format
+    that the ResXResourceWriter will generate, however the reader can
+    read any of the formats listed below.
+
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+  -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+</root>
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorRegistry.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorRegistry.cs
new file mode 100644
index 0000000..fa639c4
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionMonitorRegistry.cs
@@ -0,0 +1,56 @@
+// ConnectionMonitorRegistry.cs
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2025 Catswords OSS and WelsonJS Contributors
+// https://github.com/gnh1201/welsonjs
+//
+using System;
+using System.Collections.Generic;
+
+namespace WelsonJS.Launcher
+{
+    /// <summary>
+    /// Keeps track of connection providers that should appear in the monitor UI.
+    /// </summary>
+    public static class ConnectionMonitorRegistry
+    {
+        private static readonly object _syncRoot = new object();
+        private static readonly List<IManagedConnectionProvider> _providers = new List<IManagedConnectionProvider>();
+
+        public static void RegisterProvider(IManagedConnectionProvider provider)
+        {
+            if (provider == null)
+            {
+                throw new ArgumentNullException(nameof(provider));
+            }
+
+            lock (_syncRoot)
+            {
+                if (!_providers.Contains(provider))
+                {
+                    _providers.Add(provider);
+                }
+            }
+        }
+
+        public static void UnregisterProvider(IManagedConnectionProvider provider)
+        {
+            if (provider == null)
+            {
+                return;
+            }
+
+            lock (_syncRoot)
+            {
+                _providers.Remove(provider);
+            }
+        }
+
+        public static IReadOnlyList<IManagedConnectionProvider> GetProviders()
+        {
+            lock (_syncRoot)
+            {
+                return _providers.ToArray();
+            }
+        }
+    }
+}
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/IManagedConnectionProvider.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/IManagedConnectionProvider.cs
new file mode 100644
index 0000000..44e055a
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/IManagedConnectionProvider.cs
@@ -0,0 +1,30 @@
+// IManagedConnectionProvider.cs
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2025 Catswords OSS and WelsonJS Contributors
+// https://github.com/gnh1201/welsonjs
+//
+using System.Collections.Generic;
+
+namespace WelsonJS.Launcher
+{
+    /// <summary>
+    /// Exposes connection status information for use by the connection monitor UI.
+    /// </summary>
+    public interface IManagedConnectionProvider
+    {
+        /// <summary>
+        /// Gets a human-friendly name for the connection type managed by this provider.
+        /// </summary>
+        string ConnectionType { get; }
+
+        /// <summary>
+        /// Retrieves the current connections handled by the provider.
+        /// </summary>
+        IReadOnlyCollection<ManagedConnectionStatus> GetStatuses();
+
+        /// <summary>
+        /// Attempts to close the connection associated with the supplied cache key.
+        /// </summary>
+        bool TryClose(string key);
+    }
+}
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.Designer.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.Designer.cs
index 76ba271..e5faf00 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.Designer.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.Designer.cs
@@ -39,6 +39,7 @@
             this.settingsToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
             this.userdefinedVariablesToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
             this.instancesToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
+            this.connectionMonitorToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
             this.runAsAdministratorToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
             this.globalSettingsToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
             this.startTheEditorToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
@@ -132,6 +133,7 @@
             this.settingsToolStripMenuItem.DropDownItems.AddRange(new System.Windows.Forms.ToolStripItem[] {
             this.userdefinedVariablesToolStripMenuItem,
             this.instancesToolStripMenuItem,
+            this.connectionMonitorToolStripMenuItem,
             this.runAsAdministratorToolStripMenuItem,
             this.globalSettingsToolStripMenuItem,
             this.startTheEditorToolStripMenuItem,
@@ -153,6 +155,13 @@
             this.instancesToolStripMenuItem.Size = new System.Drawing.Size(196, 22);
             this.instancesToolStripMenuItem.Text = "Instances";
             this.instancesToolStripMenuItem.Click += new System.EventHandler(this.instancesToolStripMenuItem_Click);
+            //
+            // connectionMonitorToolStripMenuItem
+            //
+            this.connectionMonitorToolStripMenuItem.Name = "connectionMonitorToolStripMenuItem";
+            this.connectionMonitorToolStripMenuItem.Size = new System.Drawing.Size(196, 22);
+            this.connectionMonitorToolStripMenuItem.Text = "Connections...";
+            this.connectionMonitorToolStripMenuItem.Click += new System.EventHandler(this.connectionMonitorToolStripMenuItem_Click);
             // 
             // runAsAdministratorToolStripMenuItem
             // 
@@ -282,6 +291,7 @@
         private System.Windows.Forms.ToolStripMenuItem settingsToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem userdefinedVariablesToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem instancesToolStripMenuItem;
+        private System.Windows.Forms.ToolStripMenuItem connectionMonitorToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem runAsAdministratorToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem globalSettingsToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem startTheEditorToolStripMenuItem;
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.cs
index f55da4b..446650e 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/MainForm.cs
@@ -23,6 +23,7 @@ namespace WelsonJS.Launcher
         private string _workingDirectory;
         private string _instanceId;
         private string _scriptName;
+        private ConnectionMonitorForm _connectionMonitorForm;
 
         public MainForm(ICompatibleLogger logger = null)
         {
@@ -276,6 +277,17 @@ namespace WelsonJS.Launcher
             (new InstancesForm()).Show();
         }
 
+        private void connectionMonitorToolStripMenuItem_Click(object sender, EventArgs e)
+        {
+            if (_connectionMonitorForm == null || _connectionMonitorForm.IsDisposed)
+            {
+                _connectionMonitorForm = new ConnectionMonitorForm();
+            }
+
+            _connectionMonitorForm.Show();
+            _connectionMonitorForm.Focus();
+        }
+
         private void runAsAdministratorToolStripMenuItem_Click(object sender, EventArgs e)
         {
             if (!IsInAdministrator())
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ManagedConnectionStatus.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ManagedConnectionStatus.cs
new file mode 100644
index 0000000..263d5c2
--- /dev/null
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ManagedConnectionStatus.cs
@@ -0,0 +1,32 @@
+// ManagedConnectionStatus.cs
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2025 Catswords OSS and WelsonJS Contributors
+// https://github.com/gnh1201/welsonjs
+//
+namespace WelsonJS.Launcher
+{
+    /// <summary>
+    /// Represents the state of a managed connection for UI presentation.
+    /// </summary>
+    public sealed class ManagedConnectionStatus
+    {
+        public ManagedConnectionStatus(string connectionType, string key, string state, string description, bool isValid)
+        {
+            ConnectionType = connectionType ?? string.Empty;
+            Key = key ?? string.Empty;
+            State = state ?? string.Empty;
+            Description = description ?? string.Empty;
+            IsValid = isValid;
+        }
+
+        public string ConnectionType { get; }
+
+        public string Key { get; }
+
+        public string State { get; }
+
+        public string Description { get; }
+
+        public bool IsValid { get; }
+    }
+}
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
index 82d2fa3..144b5a8 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
@@ -4,6 +4,7 @@
 // https://github.com/gnh1201/welsonjs
 //
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.IO.Ports;
 using System.Text;
@@ -12,8 +13,10 @@ using System.Threading.Tasks;
 
 namespace WelsonJS.Launcher
 {
-    public sealed class SerialPortManager : ConnectionManagerBase<SerialPortManager.ConnectionParameters, SerialPort>
+    public sealed class SerialPortManager : ConnectionManagerBase<SerialPortManager.ConnectionParameters, SerialPort>, IManagedConnectionProvider
     {
+        private const string ConnectionTypeName = "Serial Port";
+
         public struct ConnectionParameters
         {
             public ConnectionParameters(
@@ -51,6 +54,13 @@ namespace WelsonJS.Launcher
             public int ReadBufferSize { get; }
         }
 
+        public SerialPortManager()
+        {
+            ConnectionMonitorRegistry.RegisterProvider(this);
+        }
+
+        public string ConnectionType => ConnectionTypeName;
+
         protected override string CreateKey(ConnectionParameters parameters)
         {
             return string.Join(",", new object[]
@@ -133,6 +143,42 @@ namespace WelsonJS.Launcher
                 cancellationToken).ConfigureAwait(false);
         }
 
+        public IReadOnlyCollection<ManagedConnectionStatus> GetStatuses()
+        {
+            var snapshots = SnapshotConnections();
+            var result = new List<ManagedConnectionStatus>(snapshots.Count);
+
+            foreach (var snapshot in snapshots)
+            {
+                string state;
+                try
+                {
+                    state = snapshot.Connection?.IsOpen == true ? "Open" : "Closed";
+                }
+                catch
+                {
+                    state = "Unknown";
+                }
+
+                var parameters = snapshot.Parameters;
+                string description = $"{parameters.PortName} @ {parameters.BaudRate} bps";
+
+                result.Add(new ManagedConnectionStatus(
+                    ConnectionTypeName,
+                    snapshot.Key,
+                    state,
+                    description,
+                    snapshot.IsValid));
+            }
+
+            return result;
+        }
+
+        public bool TryClose(string key)
+        {
+            return TryRemoveByKey(key);
+        }
+
         private static async Task<string> SendAndReceiveInternalAsync(
             SerialPort port,
             int bufferSize,
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs
index f34ebcb..433e13b 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/WebSocketManager.cs
@@ -4,6 +4,7 @@
 // https://github.com/gnh1201/welsonjs
 // 
 using System;
+using System.Collections.Generic;
 using System.Net.WebSockets;
 using System.Security.Cryptography;
 using System.Text;
@@ -12,8 +13,10 @@ using System.Threading.Tasks;
 
 namespace WelsonJS.Launcher
 {
-    public sealed class WebSocketManager : ConnectionManagerBase<WebSocketManager.Endpoint, ClientWebSocket>
+    public sealed class WebSocketManager : ConnectionManagerBase<WebSocketManager.Endpoint, ClientWebSocket>, IManagedConnectionProvider
     {
+        private const string ConnectionTypeName = "WebSocket";
+
         public struct Endpoint
         {
             public Endpoint(string host, int port, string path)
@@ -28,6 +31,13 @@ namespace WelsonJS.Launcher
             public string Path { get; }
         }
 
+        public WebSocketManager()
+        {
+            ConnectionMonitorRegistry.RegisterProvider(this);
+        }
+
+        public string ConnectionType => ConnectionTypeName;
+
         protected override string CreateKey(Endpoint parameters)
         {
             string raw = parameters.Host + ":" + parameters.Port + "/" + parameters.Path;
@@ -103,6 +113,42 @@ namespace WelsonJS.Launcher
             }
         }
 
+        public IReadOnlyCollection<ManagedConnectionStatus> GetStatuses()
+        {
+            var snapshots = SnapshotConnections();
+            var result = new List<ManagedConnectionStatus>(snapshots.Count);
+
+            foreach (var snapshot in snapshots)
+            {
+                string state;
+                try
+                {
+                    state = snapshot.Connection?.State.ToString() ?? "Unknown";
+                }
+                catch
+                {
+                    state = "Unknown";
+                }
+
+                var endpoint = snapshot.Parameters;
+                var description = $"ws://{endpoint.Host}:{endpoint.Port}/{endpoint.Path}";
+
+                result.Add(new ManagedConnectionStatus(
+                    ConnectionTypeName,
+                    snapshot.Key,
+                    state,
+                    description,
+                    snapshot.IsValid));
+            }
+
+            return result;
+        }
+
+        public bool TryClose(string key)
+        {
+            return TryRemoveByKey(key);
+        }
+
         // Actual send and receive implementation that never truncates the accumulated data.
         // - Uses a fixed-size read buffer ONLY for I/O
         // - Accumulates dynamically into a List<byte[]> until EndOfMessage
diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj b/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj
index e1fc1f4..b171397 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/WelsonJS.Launcher.csproj
@@ -89,11 +89,20 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="ConnectionManagerBase.cs" />
+    <Compile Include="ConnectionMonitorForm.cs">
+      <SubType>Form</SubType>
+    </Compile>
+    <Compile Include="ConnectionMonitorForm.Designer.cs">
+      <DependentUpon>ConnectionMonitorForm.cs</DependentUpon>
+    </Compile>
+    <Compile Include="ConnectionMonitorRegistry.cs" />
     <Compile Include="ICompatibleLogger.cs" />
+    <Compile Include="IManagedConnectionProvider.cs" />
     <Compile Include="IResourceTool.cs" />
     <Compile Include="JsCore.cs" />
     <Compile Include="JsNative.cs" />
     <Compile Include="JsSerializer.cs" />
+    <Compile Include="ManagedConnectionStatus.cs" />
     <Compile Include="NativeBootstrap.cs" />
     <Compile Include="ResourceTools\ImageColorPicker.cs" />
     <Compile Include="ResourceTools\IpQuery.cs" />
@@ -136,6 +145,9 @@
     <EmbeddedResource Include="EnvForm.resx">
       <DependentUpon>EnvForm.cs</DependentUpon>
     </EmbeddedResource>
+    <EmbeddedResource Include="ConnectionMonitorForm.resx">
+      <DependentUpon>ConnectionMonitorForm.cs</DependentUpon>
+    </EmbeddedResource>
     <EmbeddedResource Include="InstancesForm.resx">
       <DependentUpon>InstancesForm.cs</DependentUpon>
     </EmbeddedResource>

From c7890aaadb13fb63274dbc630172e92bfbee2cd6 Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 14:12:25 +0900
Subject: [PATCH 3/7] Serialize connection creation per key

---
 .../ConnectionManagerBase.cs                  | 27 ++++++++++++++++---
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
index 9bf436f..d2129f5 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
@@ -22,6 +22,8 @@ namespace WelsonJS.Launcher
     {
         private readonly ConcurrentDictionary<string, (TConnection Connection, TParameters Parameters)> _pool
             = new ConcurrentDictionary<string, (TConnection, TParameters)>();
+        private readonly ConcurrentDictionary<string, SemaphoreSlim> _openLocks
+            = new ConcurrentDictionary<string, SemaphoreSlim>();
 
         /// <summary>
         /// Creates a unique cache key for the given connection parameters.
@@ -61,11 +63,28 @@ namespace WelsonJS.Launcher
                 return existing.Connection;
             }
 
-            RemoveInternal(key, existing.Connection);
+            var gate = _openLocks.GetOrAdd(key, _ => new SemaphoreSlim(1, 1));
+            await gate.WaitAsync(token).ConfigureAwait(false);
+            try
+            {
+                if (_pool.TryGetValue(key, out existing) && IsConnectionHealthy(existing.Connection))
+                {
+                    return existing.Connection;
+                }
 
-            var connection = await OpenConnectionAsync(parameters, token).ConfigureAwait(false);
-            _pool[key] = (connection, parameters);
-            return connection;
+                if (existing.Connection != null && !IsConnectionHealthy(existing.Connection))
+                {
+                    RemoveInternal(key, existing.Connection);
+                }
+
+                var connection = await OpenConnectionAsync(parameters, token).ConfigureAwait(false);
+                _pool[key] = (connection, parameters);
+                return connection;
+            }
+            finally
+            {
+                gate.Release();
+            }
         }
 
         /// <summary>

From 7795946f9fa3b8d02df4290e23de67e26bd59989 Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 14:12:31 +0900
Subject: [PATCH 4/7] Serialize per-key operations

---
 .../WelsonJS.Launcher/ConnectionManagerBase.cs     | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
index d2129f5..5723bd2 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/ConnectionManagerBase.cs
@@ -24,6 +24,8 @@ namespace WelsonJS.Launcher
             = new ConcurrentDictionary<string, (TConnection, TParameters)>();
         private readonly ConcurrentDictionary<string, SemaphoreSlim> _openLocks
             = new ConcurrentDictionary<string, SemaphoreSlim>();
+        private readonly ConcurrentDictionary<string, SemaphoreSlim> _opLocks
+            = new ConcurrentDictionary<string, SemaphoreSlim>();
 
         /// <summary>
         /// Creates a unique cache key for the given connection parameters.
@@ -155,14 +157,16 @@ namespace WelsonJS.Launcher
             if (maxAttempts < 1) throw new ArgumentOutOfRangeException(nameof(maxAttempts));
 
             Exception lastError = null;
+            var key = CreateKey(parameters);
+            var opLock = _opLocks.GetOrAdd(key, _ => new SemaphoreSlim(1, 1));
 
             for (int attempt = 0; attempt < maxAttempts; attempt++)
             {
-                token.ThrowIfCancellationRequested();
-                var connection = await GetOrCreateAsync(parameters, token).ConfigureAwait(false);
-
+                await opLock.WaitAsync(token).ConfigureAwait(false);
                 try
                 {
+                    token.ThrowIfCancellationRequested();
+                    var connection = await GetOrCreateAsync(parameters, token).ConfigureAwait(false);
                     return await operation(connection, token).ConfigureAwait(false);
                 }
                 catch (OperationCanceledException)
@@ -178,6 +182,10 @@ namespace WelsonJS.Launcher
                         throw;
                     }
                 }
+                finally
+                {
+                    opLock.Release();
+                }
             }
 
             throw lastError ?? new InvalidOperationException("Unreachable state in ExecuteWithRetryAsync");

From 3ce8d126288b2b6c143eb78bb0cb07ff52d48894 Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 14:12:37 +0900
Subject: [PATCH 5/7] Include timeouts in serial connection key

---
 WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
index 144b5a8..fa2db4f 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
@@ -70,7 +70,9 @@ namespace WelsonJS.Launcher
                 parameters.Parity,
                 parameters.DataBits,
                 parameters.StopBits,
-                parameters.Handshake
+                parameters.Handshake,
+                parameters.ReadTimeout,
+                parameters.WriteTimeout
             });
         }
 

From 9f4219e971462a393c34b3ad2c16200bd9c7b259 Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 14:12:44 +0900
Subject: [PATCH 6/7] Make serial buffer resets optional and improve receive
 loop

---
 .../WelsonJS.Launcher/SerialPortManager.cs    | 28 +++++++++++++++----
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
index fa2db4f..21d94e8 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
@@ -28,7 +28,8 @@ namespace WelsonJS.Launcher
                 Handshake handshake = Handshake.None,
                 int readTimeout = 500,
                 int writeTimeout = 500,
-                int readBufferSize = 1024)
+                int readBufferSize = 1024,
+                bool resetBuffersBeforeRequest = false)
             {
                 if (string.IsNullOrWhiteSpace(portName)) throw new ArgumentNullException(nameof(portName));
 
@@ -41,6 +42,7 @@ namespace WelsonJS.Launcher
                 ReadTimeout = readTimeout;
                 WriteTimeout = writeTimeout;
                 ReadBufferSize = readBufferSize > 0 ? readBufferSize : 1024;
+                ResetBuffersBeforeRequest = resetBuffersBeforeRequest;
             }
 
             public string PortName { get; }
@@ -52,6 +54,7 @@ namespace WelsonJS.Launcher
             public int ReadTimeout { get; }
             public int WriteTimeout { get; }
             public int ReadBufferSize { get; }
+            public bool ResetBuffersBeforeRequest { get; }
         }
 
         public SerialPortManager()
@@ -140,7 +143,13 @@ namespace WelsonJS.Launcher
 
             return await ExecuteWithRetryAsync(
                 parameters,
-                (port, token) => SendAndReceiveInternalAsync(port, parameters.ReadBufferSize, payload, encoding, token),
+                (port, token) => SendAndReceiveInternalAsync(
+                    port,
+                    parameters.ReadBufferSize,
+                    payload,
+                    encoding,
+                    parameters.ResetBuffersBeforeRequest,
+                    token),
                 2,
                 cancellationToken).ConfigureAwait(false);
         }
@@ -186,10 +195,14 @@ namespace WelsonJS.Launcher
             int bufferSize,
             byte[] payload,
             Encoding encoding,
+            bool resetBuffers,
             CancellationToken token)
         {
-            port.DiscardInBuffer();
-            port.DiscardOutBuffer();
+            if (resetBuffers)
+            {
+                port.DiscardInBuffer();
+                port.DiscardOutBuffer();
+            }
 
             if (payload.Length > 0)
             {
@@ -208,14 +221,17 @@ namespace WelsonJS.Launcher
                         if (read > 0)
                         {
                             stream.Write(buffer, 0, read);
-                            if (read < buffer.Length)
+                            if (port.BytesToRead == 0)
                             {
                                 break;
                             }
                         }
                         else
                         {
-                            break;
+                            if (port.BytesToRead == 0)
+                            {
+                                break;
+                            }
                         }
                     }
                     catch (TimeoutException)

From 4489c3150919db2bc937f6e730c5e7a3c6427262 Mon Sep 17 00:00:00 2001
From: "Namhyeon, Go" <gnh1201@catswords.re.kr>
Date: Tue, 28 Oct 2025 16:36:58 +0900
Subject: [PATCH 7/7] Guard serial reads with timeout-based termination and cap

---
 .../WelsonJS.Launcher/SerialPortManager.cs       | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
index 21d94e8..feadbcd 100644
--- a/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Launcher/SerialPortManager.cs
@@ -212,7 +212,7 @@ namespace WelsonJS.Launcher
             using (var stream = new MemoryStream())
             {
                 var buffer = new byte[bufferSize];
-
+                const int MaxResponseBytes = 1 * 1024 * 1024; // 1 MiB safety cap
                 while (true)
                 {
                     try
@@ -220,18 +220,10 @@ namespace WelsonJS.Launcher
                         int read = await Task.Run(() => port.Read(buffer, 0, buffer.Length), token).ConfigureAwait(false);
                         if (read > 0)
                         {
+                            if (stream.Length + read > MaxResponseBytes)
+                                throw new InvalidOperationException("Serial response exceeded maximum allowed size.");
                             stream.Write(buffer, 0, read);
-                            if (port.BytesToRead == 0)
-                            {
-                                break;
-                            }
-                        }
-                        else
-                        {
-                            if (port.BytesToRead == 0)
-                            {
-                                break;
-                            }
+                            continue; // keep reading until idle timeout
                         }
                     }
                     catch (TimeoutException)