feat: add password protection for channels

- Updated IChatService to include password parameter in JoinChannelAsync method.
- Modified ChannelDto and related models to support password functionality.
- Implemented password handling in ChannelService for channel creation and membership validation.
- Enhanced IrcCommandHandler to manage channel join requests with passwords.
- Added ChannelPasswordDialog for user input when joining protected channels.
- Created database migration to add PasswordHash column to Channels table.
- Updated tests to cover new password functionality in channel joining and management.

src/EchoHub.Client/AppOrchestrator.cs

@@ -216,13 +216,15 @@ public sealed class AppOrchestrator : IDisposable
         return Task.CompletedTask;
     }
 
-    private async Task HandleCmdJoinChannel(string channelName)
+    private async Task HandleCmdJoinChannel(string channelName, string? password)
     {
         if (!_conn.IsConnected) return;
 
         try
         {
-            var history = await _conn.JoinChannelAsync(channelName);
+            var history = await JoinChannelWithPasswordPromptAsync(channelName, password);
+            if (history is null) return; // user cancelled the password prompt
+
             InvokeUI(() =>
             {
                 _mainWindow.EnsureChannelInList(channelName);
@@ -237,6 +239,31 @@ public sealed class AppOrchestrator : IDisposable
         }
     }
 
+    /// <summary>
+    /// Joins a channel, prompting for a password when the server requires one and
+    /// re-prompting on a wrong password. Returns the channel history, or null if
+    /// the user cancelled the prompt.
+    /// </summary>
+    private async Task<List<MessageDto>?> JoinChannelWithPasswordPromptAsync(string channelName, string? password)
+    {
+        while (true)
+        {
+            try
+            {
+                return await _conn.JoinChannelAsync(channelName, password);
+            }
+            catch (ChannelPasswordRequiredException ex)
+            {
+                var prompt = new TaskCompletionSource<string?>(TaskCreationOptions.RunContinuationsAsynchronously);
+                var message = password is not null ? ex.Message : null;
+                InvokeUI(() => prompt.SetResult(ChannelPasswordDialog.Show(_app, channelName, message)));
+
+                password = await prompt.Task;
+                if (password is null) return null;
+            }
+        }
+    }
+
     private async Task HandleCmdLeaveChannel()
     {
         if (!_conn.IsConnected) return;
@@ -554,7 +581,7 @@ public sealed class AppOrchestrator : IDisposable
             InvokeUI(() =>
             {
                 if (channel.IsPublic)
-                    _mainWindow.EnsureChannelInList(channel.Name, channel.IsPublic);
+                    _mainWindow.EnsureChannelInList(channel.Name, channel.IsPublic, channel.IsProtected);
                 _mainWindow.SetChannelTopic(channel.Name, channel.Topic);
             });
         };
@@ -707,7 +734,16 @@ public sealed class AppOrchestrator : IDisposable
         RunAsync(async () =>
         {
             if (_conn.TrackChannel(channelName))
-                await _conn.JoinChannelAsync(channelName);
+            {
+                var joined = await JoinChannelWithPasswordPromptAsync(channelName, null);
+                if (joined is null)
+                {
+                    // User cancelled the password prompt — back to the default channel
+                    _conn.UntrackChannel(channelName);
+                    InvokeUI(() => _mainWindow.SwitchToChannel(HubConstants.DefaultChannel));
+                    return;
+                }
+            }
 
             try
             {
@@ -983,14 +1019,14 @@ public sealed class AppOrchestrator : IDisposable
 
         RunAsync(async () =>
         {
-            var channel = await _conn.Api!.CreateChannelAsync(result.Name, result.Topic, result.IsPublic);
+            var channel = await _conn.Api!.CreateChannelAsync(result.Name, result.Topic, result.IsPublic, result.Password);
             if (channel is null) return;
 
             var history = await _conn.JoinChannelAsync(channel.Name);
 
             InvokeUI(() =>
             {
-                _mainWindow.EnsureChannelInList(channel.Name);
+                _mainWindow.EnsureChannelInList(channel.Name, channel.IsPublic, channel.IsProtected);
                 _mainWindow.SetChannelTopic(channel.Name, channel.Topic);
                 _mainWindow.SwitchToChannel(channel.Name);
                 if (history.Count > 0)

src/EchoHub.Client/Commands/CommandHandler.cs

@@ -13,7 +13,7 @@ public class CommandHandler
     public event Func<string, string?, Task>? OnSendFile;
     public event Func<string?, Task>? OnOpenProfile;
     public event Func<Task>? OnOpenServers;
-    public event Func<string, Task>? OnJoinChannel;
+    public event Func<string, string?, Task>? OnJoinChannel;
     public event Func<Task>? OnLeaveChannel;
     public event Func<string, Task>? OnSetTopic;
     public event Func<Task>? OnListUsers;
@@ -126,7 +126,7 @@ public class CommandHandler
     private async Task<CommandResult> HandleTheme(string args)
     {
         if (string.IsNullOrWhiteSpace(args))
-            return new CommandResult(true, "Usage: /theme <name> (Default, Dark, Light, Hacker, Solarized)", IsError: true);
+            return new CommandResult(true, "Usage: /theme <name> — pick one from the User menu's theme list (e.g. Default, Transparent, TransparentLight, Hacker)", IsError: true);
 
         if (OnSetTheme is not null)
             await OnSetTheme(args.Trim());
@@ -193,11 +193,14 @@ public class CommandHandler
     private async Task<CommandResult> HandleJoin(string args)
     {
         if (string.IsNullOrWhiteSpace(args))
-            return new CommandResult(true, "Usage: /join <channel>", IsError: true);
+            return new CommandResult(true, "Usage: /join <channel> [password]", IsError: true);
+
+        var parts = args.Trim().Split(' ', 2, StringSplitOptions.TrimEntries);
+        var channel = parts[0].TrimStart('#');
+        var password = parts.Length > 1 && !string.IsNullOrWhiteSpace(parts[1]) ? parts[1] : null;
 
-        var channel = args.Trim().TrimStart('#');
         if (OnJoinChannel is not null)
-            await OnJoinChannel(channel);
+            await OnJoinChannel(channel, password);
         return new CommandResult(true);
     }
 
@@ -343,7 +346,7 @@ public class CommandHandler
               /avatar <URL or filepath>             - Set your avatar
               /profile [username]                   - View a profile
               /servers                             - Open saved servers
-              /join <channel>                      - Join a channel
+              /join <channel> [password]           - Join a channel (password if protected)
               /leave                               - Leave current channel
               /topic <text>                        - Set channel topic
               /users                               - List online users

src/EchoHub.Client/Services/ApiClient.cs

@@ -228,10 +228,10 @@ public sealed class ApiClient : IDisposable
         return tempPath;
     }
 
-    public async Task<ChannelDto?> CreateChannelAsync(string name, string? topic = null, bool isPublic = true)
+    public async Task<ChannelDto?> CreateChannelAsync(string name, string? topic = null, bool isPublic = true, string? password = null)
     {
         EnsureAuthenticated();
-        var request = new CreateChannelRequest(name, topic, isPublic);
+        var request = new CreateChannelRequest(name, topic, isPublic, password);
         using var response = await AuthenticatedRequestAsync(() =>
             _http.PostAsJsonAsync("/api/channels", request));
         await EnsureSuccessAsync(response);

src/EchoHub.Client/Services/ConnectionManager.cs

@@ -169,11 +169,21 @@ internal sealed class ConnectionManager : IAsyncDisposable
 
     // ── Channel Operations ────────────────────────────────────────────────
 
-    public async Task<List<MessageDto>> JoinChannelAsync(string channelName)
+    public async Task<List<MessageDto>> JoinChannelAsync(string channelName, string? password = null)
     {
         if (_connection is null) throw new InvalidOperationException("Not connected");
-        _joinedChannels.Add(channelName);
-        return await _connection.JoinChannelAsync(channelName);
+        try
+        {
+            var history = await _connection.JoinChannelAsync(channelName, password);
+            _joinedChannels.Add(channelName);
+            return history;
+        }
+        catch (ChannelPasswordRequiredException)
+        {
+            // Not actually joined — don't track, or reconnects would retry a doomed join
+            _joinedChannels.Remove(channelName);
+            throw;
+        }
     }
 
     public async Task LeaveChannelAsync(string channelName)

src/EchoHub.Client/Services/EchoHubConnection.cs

@@ -5,6 +5,20 @@ using Microsoft.AspNetCore.SignalR.Client;
 
 namespace EchoHub.Client.Services;
 
+/// <summary>
+/// Thrown when joining a channel fails because a password is required or incorrect.
+/// The UI catches this to prompt the user and retry.
+/// </summary>
+public sealed class ChannelPasswordRequiredException : Exception
+{
+    public string ChannelName { get; }
+
+    public ChannelPasswordRequiredException(string channelName, string message) : base(message)
+    {
+        ChannelName = channelName;
+    }
+}
+
 public sealed class EchoHubConnection : IAsyncDisposable
 {
     private readonly HubConnection _connection;
@@ -134,11 +148,15 @@ public sealed class EchoHubConnection : IAsyncDisposable
         OnConnectionStateChanged?.Invoke("Disconnected");
     }
 
-    public async Task<List<MessageDto>> JoinChannelAsync(string channelName)
+    public async Task<List<MessageDto>> JoinChannelAsync(string channelName, string? password = null)
     {
-        var result = await _connection.InvokeAsync<JoinChannelResult>("JoinChannel", channelName);
+        var result = await _connection.InvokeAsync<JoinChannelResult>("JoinChannel", channelName, password);
         if (!result.Success)
+        {
+            if (result.PasswordRequired)
+                throw new ChannelPasswordRequiredException(channelName, result.Error ?? "Channel is password protected.");
             throw new InvalidOperationException(result.Error ?? "Failed to join channel.");
+        }
         return DecryptMessages(result.History);
     }
 

src/EchoHub.Client/Themes/ThemeManager.cs

@@ -445,10 +445,44 @@ public static class ThemeManager
         }
     };
 
+    private static readonly Theme TransparentLightTheme = new()
+    {
+        Name = "TransparentLight",
+        Base = new ThemeColors
+        {
+            Foreground = "Black",
+            Background = "None",
+            FocusForeground = "Blue",
+            FocusBackground = "None"
+        },
+        Menu = new ThemeColors
+        {
+            Foreground = "Black",
+            Background = "None",
+            FocusForeground = "Blue",
+            FocusBackground = "None"
+        },
+        Dialog = new ThemeColors
+        {
+            Foreground = "Black",
+            Background = "Gray",
+            FocusForeground = "Blue",
+            FocusBackground = "White"
+        },
+        Status = new ThemeColors
+        {
+            Foreground = "DarkGray",
+            Background = "None",
+            FocusForeground = "DarkGray",
+            FocusBackground = "None"
+        }
+    };
+
     private static readonly List<Theme> BuiltInThemes =
     [
         DefaultTheme,
         TransparentTheme,
+        TransparentLightTheme,
         ClassicTheme,
         LightTheme,
         HackerTheme,

src/EchoHub.Client/UI/Dialogs/ChannelPasswordDialog.cs

@@ -0,0 +1,72 @@
+using Terminal.Gui.App;
+using Terminal.Gui.ViewBase;
+using Terminal.Gui.Views;
+
+namespace EchoHub.Client.UI.Dialogs;
+
+/// <summary>
+/// Prompts for a channel password when joining a protected channel.
+/// Returns the entered password, or null if the user cancels.
+/// </summary>
+public sealed class ChannelPasswordDialog
+{
+    public static string? Show(IApplication app, string channelName, string? message = null)
+    {
+        string? result = null;
+
+        var dialog = new Dialog { Title = $"Join #{channelName}", Width = 50, Height = 10, CommandsToBubbleUp = [] };
+
+        var infoLabel = new Label
+        {
+            Text = message ?? $"#{channelName} is password protected.",
+            X = 1,
+            Y = 1
+        };
+
+        var passwordLabel = new Label { Text = "Password:", X = 1, Y = 3 };
+        var passwordField = new TextField { X = 11, Y = 3, Width = Dim.Fill(2), Secret = true };
+
+        var joinButton = new Button
+        {
+            Text = "Join",
+            IsDefault = true,
+            X = Pos.Center() - 9,
+            Y = 5
+        };
+
+        var cancelButton = new Button
+        {
+            Text = "Cancel",
+            X = Pos.Center() + 2,
+            Y = 5
+        };
+
+        joinButton.Accepting += (s, e) =>
+        {
+            var password = passwordField.Text;
+            if (string.IsNullOrEmpty(password))
+            {
+                MessageBox.ErrorQuery(app, "Error", "Password is required.", "OK");
+                return;
+            }
+
+            result = password;
+            e.Handled = true;
+            app.RequestStop();
+        };
+
+        cancelButton.Accepting += (s, e) =>
+        {
+            result = null;
+            e.Handled = true;
+            app.RequestStop();
+        };
+
+        dialog.Add(infoLabel, passwordLabel, passwordField, joinButton, cancelButton);
+
+        passwordField.SetFocus();
+        app.Run(dialog);
+
+        return result;
+    }
+}

src/EchoHub.Client/UI/Dialogs/CreateChannelDialog.cs

@@ -4,7 +4,7 @@ using Terminal.Gui.ViewBase;
 
 namespace EchoHub.Client.UI.Dialogs;
 
-public record CreateChannelResult(string Name, string? Topic, bool IsPublic);
+public record CreateChannelResult(string Name, string? Topic, bool IsPublic, string? Password);
 
 public sealed class CreateChannelDialog
 {
@@ -12,7 +12,7 @@ public sealed class CreateChannelDialog
     {
         CreateChannelResult? result = null;
 
-        var dialog = new Dialog { Title = "Create Channel", Width = 50, Height = 14, CommandsToBubbleUp = [] };
+        var dialog = new Dialog { Title = "Create Channel", Width = 50, Height = 16, CommandsToBubbleUp = [] };
 
         var nameLabel = new Label { Text = "Name:", X = 1, Y = 1 };
         var nameField = new TextField { X = 10, Y = 1, Width = Dim.Fill(2) };
@@ -20,19 +20,22 @@ public sealed class CreateChannelDialog
         var topicLabel = new Label { Text = "Topic:", X = 1, Y = 3 };
         var topicField = new TextField { X = 10, Y = 3, Width = Dim.Fill(2) };
 
+        var passwordLabel = new Label { Text = "Password:", X = 1, Y = 5 };
+        var passwordField = new TextField { X = 11, Y = 5, Width = Dim.Fill(2), Secret = true };
+
         var publicCheckbox = new CheckBox
         {
             Text = "Public (visible to all users)",
             X = 1,
-            Y = 5,
+            Y = 7,
             Value = CheckState.Checked
         };
 
         var hintLabel = new Label
         {
-            Text = "Lowercase letters, digits, hyphens, underscores (2-100 chars)",
+            Text = "Name: a-z, 0-9, -, _ (2-100 chars). Empty password = open channel.",
             X = 1,
-            Y = 7,
+            Y = 9,
         };
 
         var createButton = new Button
@@ -40,14 +43,14 @@ public sealed class CreateChannelDialog
             Text = "Create",
             IsDefault = true,
             X = Pos.Center() - 10,
-            Y = 9
+            Y = 11
         };
 
         var cancelButton = new Button
         {
             Text = "Cancel",
             X = Pos.Center() + 5,
-            Y = 9
+            Y = 11
         };
 
         createButton.Accepting += (s, e) =>
@@ -63,8 +66,12 @@ public sealed class CreateChannelDialog
             if (string.IsNullOrWhiteSpace(topic))
                 topic = null;
 
+            var password = passwordField.Text;
+            if (string.IsNullOrWhiteSpace(password))
+                password = null;
+
             var isPublic = publicCheckbox.Value == CheckState.Checked;
-            result = new CreateChannelResult(name, topic, isPublic);
+            result = new CreateChannelResult(name, topic, isPublic, password);
             e.Handled = true;
             app.RequestStop();
         };
@@ -76,7 +83,8 @@ public sealed class CreateChannelDialog
             app.RequestStop();
         };
 
-        dialog.Add(nameLabel, nameField, topicLabel, topicField, publicCheckbox, hintLabel, createButton, cancelButton);
+        dialog.Add(nameLabel, nameField, topicLabel, topicField, passwordLabel, passwordField,
+            publicCheckbox, hintLabel, createButton, cancelButton);
 
         nameField.SetFocus();
         app.Run(dialog);

src/EchoHub.Client/UI/ListSources/ChannelListSource.cs

@@ -16,6 +16,7 @@ public class ChannelListSource : IListDataSource
 {
     private readonly List<string> _channelNames = [];
     private readonly Dictionary<string, int> _unreadCounts = [];
+    private readonly HashSet<string> _protectedChannels = [];
     private string _activeChannel = string.Empty;
 
     public event NotifyCollectionChangedEventHandler? CollectionChanged;
@@ -28,13 +29,17 @@ public class ChannelListSource : IListDataSource
     private static readonly Attribute NormalAttr = new(Color.DarkGray, Color.None);
     private static readonly Attribute BadgeAttr = new(Color.BrightYellow, Color.None);
 
-    public void Update(List<string> channels, Dictionary<string, int> unread, string activeChannel)
+    public void Update(List<string> channels, Dictionary<string, int> unread, string activeChannel,
+        IReadOnlySet<string>? protectedChannels = null)
     {
         _channelNames.Clear();
         _channelNames.AddRange(channels);
         _unreadCounts.Clear();
         foreach (var kv in unread)
             _unreadCounts[kv.Key] = kv.Value;
+        _protectedChannels.Clear();
+        if (protectedChannels is not null)
+            _protectedChannels.UnionWith(protectedChannels);
         _activeChannel = activeChannel;
         MaxItemLength = channels.Count > 0 ? channels.Max(c => c.Length + 6) : 0;
         if (!SuspendCollectionChangedEvent)
@@ -57,7 +62,8 @@ public class ChannelListSource : IListDataSource
         var normalAttr = listView.GetAttributeForRole(VisualRole.Normal);
         var focusAttr = listView.GetAttributeForRole(VisualRole.Focus);
         var prefix = isActive ? "> " : "  ";
-        var channelText = $"#{name}";
+        // Trailing * marks password-protected (+k) channels
+        var channelText = _protectedChannels.Contains(name) ? $"#{name}*" : $"#{name}";
         var badge = hasUnread ? $" ({unread})" : "";
 
         // Resolve Transparent backgrounds to the view's actual background

src/EchoHub.Client/UI/MainWindow.cs

@@ -7,6 +7,7 @@ using EchoHub.Client.UI.Helpers;
 using EchoHub.Client.UI.ListSources;
 using EchoHub.Core.DTOs;
 using EchoHub.Core.Models;
+using Serilog;
 using Terminal.Gui.App;
 using Terminal.Gui.Configuration;
 using Terminal.Gui.Drawing;
@@ -50,6 +51,10 @@ public sealed partial class MainWindow : Runnable
     private static readonly Key AltQKey = Key.Q.WithAlt;
     private static readonly Key TabKey = Key.Tab;
     private static readonly Key CtrlKKey = Key.K.WithCtrl;
+    private static readonly Key CtrlVKey = Key.V.WithCtrl;
+    private static readonly Key CtrlXKey = Key.X.WithCtrl;
+    private static readonly Key CtrlCKey = Key.C.WithCtrl;
+    private static readonly Key CtrlYKey = Key.Y.WithCtrl;
 
     // Available slash commands for Tab autocomplete
     private static readonly string[] SlashCommands =
@@ -63,6 +68,7 @@ public sealed partial class MainWindow : Runnable
     private readonly List<string> _channelNames = [];
     private readonly Dictionary<string, string?> _channelTopics = [];
     private readonly Dictionary<string, bool> _channelPublic = [];
+    private readonly HashSet<string> _channelProtected = [];
     private readonly ChannelListSource _channelListSource;
     private readonly ChatMessageManager _messageManager;
     private string _connectionStatus = "Disconnected";
@@ -253,6 +259,10 @@ public sealed partial class MainWindow : Runnable
             Height = Dim.Fill(),
             WordWrap = true
         };
+        // Terminal.Gui binds Ctrl+W to Command.Cut, whose OS clipboard write can throw
+        // Win32Exception when another process holds the clipboard, crashing the app.
+        // Rebind it to delete-word-backward (readline behavior), which never touches the clipboard.
+        _inputField.KeyBindings.ReplaceCommands(Key.W.WithCtrl, Command.KillWordLeft);
         _inputField.KeyDown += OnInputKeyDown;
         _inputField.ContentsChanged += OnInputContentsChanged;
         _inputFrame.Add(_inputField);
@@ -540,19 +550,81 @@ public sealed partial class MainWindow : Runnable
             ShowSearchDialog();
             e.Handled = true;
         }
+        else if (e.KeyCode == CtrlVKey.KeyCode || e.KeyCode == CtrlYKey.KeyCode)
+        {
+            // Explicit paste support: terminals that don't intercept Ctrl+V themselves
+            // otherwise leave users with only the right-click context menu.
+            GuardedClipboardAction(() => _inputField.Paste(), "paste");
+            e.Handled = true;
+        }
+        else if (e.KeyCode == CtrlXKey.KeyCode)
+        {
+            GuardedClipboardAction(() => _inputField.Cut(), "cut");
+            e.Handled = true;
+        }
+        else if (e.KeyCode == CtrlCKey.KeyCode)
+        {
+            GuardedClipboardAction(() => _inputField.Copy(), "copy");
+            e.Handled = true;
+        }
+    }
+
+    /// <summary>
+    /// Runs a clipboard-backed edit action, swallowing transient OS clipboard failures
+    /// (e.g. another process holding the Windows clipboard) that would otherwise
+    /// propagate out of the input loop and crash the app.
+    /// </summary>
+    private static void GuardedClipboardAction(Action action, string operation)
+    {
+        try
+        {
+            action();
+        }
+        catch (Exception ex)
+        {
+            Log.Warning(ex, "Clipboard {Operation} failed", operation);
+        }
     }
 
     private bool _suppressEmojiReplace;
+    private int _lastInputLength;
 
     private void OnInputContentsChanged(object? sender, ContentsChangedEventArgs e)
     {
+        var text = _inputField.Text;
+        var previousLength = _lastInputLength;
+        _lastInputLength = text?.Length ?? 0;
+
         if (_suppressEmojiReplace)
             return;
 
-        var text = _inputField.Text;
         if (string.IsNullOrEmpty(text))
             return;
 
+        // A file dropped onto the terminal arrives as a pasted absolute path.
+        // Detect multi-char bursts that resolve to existing files and route them
+        // through /send instead of leaving a raw path in the input.
+        if (text.Length - previousLength > 3 && TryGetDroppedFiles(text, out var droppedFiles))
+        {
+            var channel = _messageManager.CurrentChannel;
+            if (!string.IsNullOrEmpty(channel))
+            {
+                _suppressEmojiReplace = true;
+                try
+                {
+                    _inputField.Text = string.Empty;
+                }
+                finally
+                {
+                    _suppressEmojiReplace = false;
+                }
+
+                foreach (var file in droppedFiles)
+                    OnMessageSubmitted?.Invoke(channel, $"/send \"{file}\"");
+                return;
+            }
+        }
+
         var replaced = EmojiHelper.ReplaceEmoji(text);
         if (replaced == text)
             return;
@@ -562,9 +634,15 @@ public sealed partial class MainWindow : Runnable
         var newCol = Math.Max(0, _inputField.CurrentColumn + lengthDelta);
 
         _suppressEmojiReplace = true;
-        _inputField.Text = replaced;
-        _inputField.InsertionPoint = new System.Drawing.Point(newCol, _inputField.CurrentRow);
-        _suppressEmojiReplace = false;
+        try
+        {
+            _inputField.Text = replaced;
+            _inputField.InsertionPoint = new System.Drawing.Point(newCol, _inputField.CurrentRow);
+        }
+        finally
+        {
+            _suppressEmojiReplace = false;
+        }
     }
 
     /// <summary>
@@ -604,6 +682,80 @@ public sealed partial class MainWindow : Runnable
         _inputField.InsertionPoint = new System.Drawing.Point(_inputField.Text?.Length ?? 0, 0);
     }
 
+    /// <summary>
+    /// Interprets pasted text as one or more dropped files. Terminals deliver a file drop
+    /// as the absolute path (quoted when it contains spaces; multiple files space-separated).
+    /// Returns true only when the entire input resolves to existing files.
+    /// </summary>
+    private static bool TryGetDroppedFiles(string text, out List<string> files)
+    {
+        files = [];
+
+        var trimmed = text.Trim();
+        if (trimmed.Length < 3 || trimmed.Length > 4096 || trimmed.Contains('\n'))
+            return false;
+
+        // Single unquoted path, possibly with spaces (e.g. WSL or plain conhost drops)
+        var unquoted = StripQuotes(trimmed);
+        if (Path.IsPathFullyQualified(unquoted) && File.Exists(unquoted))
+        {
+            files.Add(unquoted);
+            return true;
+        }
+
+        // Multiple files: space-separated tokens, each optionally quoted
+        foreach (var token in TokenizeQuoted(trimmed))
+        {
+            if (!Path.IsPathFullyQualified(token) || !File.Exists(token))
+            {
+                files.Clear();
+                return false;
+            }
+            files.Add(token);
+        }
+
+        return files.Count > 0;
+    }
+
+    private static string StripQuotes(string s) =>
+        s.Length >= 2 && ((s[0] == '"' && s[^1] == '"') || (s[0] == '\'' && s[^1] == '\''))
+            ? s[1..^1]
+            : s;
+
+    private static IEnumerable<string> TokenizeQuoted(string input)
+    {
+        var current = new System.Text.StringBuilder();
+        var quote = '\0';
+
+        foreach (var c in input)
+        {
+            if (quote != '\0')
+            {
+                if (c == quote) quote = '\0';
+                else current.Append(c);
+            }
+            else if (c is '"' or '\'')
+            {
+                quote = c;
+            }
+            else if (c == ' ')
+            {
+                if (current.Length > 0)
+                {
+                    yield return current.ToString();
+                    current.Clear();
+                }
+            }
+            else
+            {
+                current.Append(c);
+            }
+        }
+
+        if (current.Length > 0)
+            yield return current.ToString();
+    }
+
     private void OnChatViewportChanged()
     {
         var newWidth = _messageList.Viewport.Width;
@@ -675,11 +827,14 @@ public sealed partial class MainWindow : Runnable
         _channelNames.Clear();
         _channelTopics.Clear();
         _channelPublic.Clear();
+        _channelProtected.Clear();
         foreach (var ch in channels)
         {
             _channelNames.Add(ch.Name);
             _channelTopics[ch.Name] = ch.Topic;
             _channelPublic[ch.Name] = ch.IsPublic;
+            if (ch.IsProtected)
+                _channelProtected.Add(ch.Name);
         }
         RefreshChannelList();
     }
@@ -687,13 +842,23 @@ public sealed partial class MainWindow : Runnable
     /// <summary>
     /// Ensure a channel exists in the left panel list (used for private channels joined via /join).
     /// </summary>
-    public void EnsureChannelInList(string channelName, bool? isPublic = null)
+    public void EnsureChannelInList(string channelName, bool? isPublic = null, bool? isProtected = null)
     {
         if (isPublic.HasValue)
             _channelPublic[channelName] = isPublic.Value;
 
+        if (isProtected.HasValue)
+        {
+            if (isProtected.Value) _channelProtected.Add(channelName);
+            else _channelProtected.Remove(channelName);
+        }
+
         if (_channelNames.Contains(channelName))
+        {
+            if (isProtected.HasValue)
+                RefreshChannelList();
             return;
+        }
 
         _channelNames.Add(channelName);
         RefreshChannelList();
@@ -707,6 +872,7 @@ public sealed partial class MainWindow : Runnable
         _channelNames.Remove(channelName);
         _channelTopics.Remove(channelName);
         _channelPublic.Remove(channelName);
+        _channelProtected.Remove(channelName);
         RefreshChannelList();
     }
 
@@ -792,6 +958,8 @@ public sealed partial class MainWindow : Runnable
         {
             _channelPublic.TryGetValue(currentChannel, out var isPublic);
             var typeSuffix = isPublic ? "public" : "private";
+            if (_channelProtected.Contains(currentChannel))
+                typeSuffix += " +k";
             Write($" \u2502 #{currentChannel} - {typeSuffix}", normalAttr);
         }
 
@@ -855,6 +1023,7 @@ public sealed partial class MainWindow : Runnable
         _messageManager.ClearAll();
         _channelTopics.Clear();
         _channelPublic.Clear();
+        _channelProtected.Clear();
         _channelListSource.Update([], [], string.Empty);
         _channelList.Source = _channelListSource;
         _chatFrame.Title = "Chat";
@@ -915,7 +1084,7 @@ public sealed partial class MainWindow : Runnable
     /// </summary>
     private void RefreshChannelList()
     {
-        _channelListSource.Update(_channelNames, _messageManager.GetUnreadCounts(), _messageManager.CurrentChannel);
+        _channelListSource.Update(_channelNames, _messageManager.GetUnreadCounts(), _messageManager.CurrentChannel, _channelProtected);
         _channelList.Source = _channelListSource;
 
         // Restore selection to current channel