feat: Add support for message attachments

- Introduced Attachment model to handle file attachments associated with messages.
- Updated ModerationController to manage message deletions and attachment cleanup.
- Enhanced ChatService to include attachments in message retrieval.
- Implemented migration for legacy single-attachment messages to the new Attachments model.
- Added unit tests for attachment handling in message formatting and parsing.
- Updated database context and migrations to support new Attachments table.

src/EchoHub.Client/UI/Chat/ChatLine.cs

@@ -18,7 +18,7 @@ public partial class ChatLine
     public bool IsMention { get; set; }
     public string? AttachmentUrl { get; set; }
     public string? AttachmentFileName { get; set; }
-    public MessageType? Type { get; set; }
+    public AttachmentKind? AttachmentKind { get; set; }
     public string? SenderUsername { get; set; }
     /// <summary>Number of spaces to prepend on continuation lines when this line is word-wrapped.</summary>
     public int ContinuationIndent { get; set; }
@@ -124,7 +124,7 @@ public partial class ChatLine
         {
             wrapped.AttachmentUrl = AttachmentUrl;
             wrapped.AttachmentFileName = AttachmentFileName;
-            wrapped.Type = Type;
+            wrapped.AttachmentKind = AttachmentKind;
             wrapped.MessageId = MessageId;
             wrapped.SenderUsername = SenderUsername;
         }

src/EchoHub.Client/UI/Chat/ChatMessageManager.cs

@@ -238,86 +238,77 @@ public sealed class ChatMessageManager
         var senderName = message.SenderUsername + ":";
         var senderColor = HexColorHelper.ParseHexColor(message.SenderNicknameColor);
 
+        var indent = new string(' ', $"[{time}] {senderName} ".Length);
+        var pad = new string(' ', 7);
+
         var lines = new List<ChatLine>();
+        var hasContent = !string.IsNullOrWhiteSpace(message.Content);
+        var attachments = message.Attachments ?? [];
 
-        switch (message.Type)
+        // Header line: caption text, or a summary when the message is attachments-only
+        if (hasContent)
         {
-            case MessageType.Image:
-                lines.Add(BuildChatLine(time, senderName, senderColor, " [Image]"));
-                if (!string.IsNullOrWhiteSpace(message.Content))
-                {
-                    foreach (var artLine in message.Content.Split('\n'))
+            var displayContent = EmojiHelper.ReplaceEmoji(message.Content);
+            var contentLines = displayContent.Split('\n');
+            lines.Add(BuildChatLineWithMentions(time, senderName, senderColor, $" {contentLines[0].TrimEnd('\r')}"));
+            for (int i = 1; i < contentLines.Length; i++)
+                lines.Add(new ChatLine(ChatColors.SplitMentions($"{indent}{contentLines[i].TrimEnd('\r')}")));
+        }
+        else
+        {
+            var summary = attachments.Count switch
+            {
+                0 => " ",
+                1 => $" [{attachments[0].Kind.ToString().ToLowerInvariant()}]",
+                _ => $" [{attachments.Count} attachments]",
+            };
+            lines.Add(BuildChatLine(time, senderName, senderColor, summary));
+        }
+
+        foreach (var l in lines)
+            l.ContinuationIndent = indent.Length;
+
+        // One block per attachment
+        foreach (var attachment in attachments)
+        {
+            switch (attachment.Kind)
+            {
+                case Core.Models.AttachmentKind.Image:
+                    if (!string.IsNullOrWhiteSpace(attachment.AsciiPreview))
                     {
-                        var trimmed = artLine.TrimEnd('\r');
-                        if (ChatLine.HasColorTags(trimmed))
-                            lines.Add(ChatLine.FromColoredText("       " + trimmed));
-                        else
-                            lines.Add(new ChatLine($"       {trimmed}"));
+                        foreach (var artLine in attachment.AsciiPreview.Split('\n'))
+                        {
+                            var trimmed = artLine.TrimEnd('\r');
+                            lines.Add(ChatLine.HasColorTags(trimmed)
+                                ? ChatLine.FromColoredText(pad + trimmed)
+                                : new ChatLine($"{pad}{trimmed}"));
+                        }
                     }
-                }
+                    lines.Add(AttachmentActionLine(pad,
+                        $"[↓ save original] {attachment.FileName} [{FormatFileSize(attachment.FileSize)}]",
+                        ChatColors.FileAttr, attachment));
+                    break;
 
-                // Clickable action to download the original image below the ASCII art
-                if (message.AttachmentUrl is not null)
-                {
-                    var imageName = message.AttachmentFileName ?? "image";
-                    var imageSize = FormatFileSize(message.AttachmentFileSize);
-                    var saveLine = new ChatLine(new List<ChatSegment>
-                    {
-                        new("       ", null),
-                        new($"[↓ save original] {imageName} [{imageSize}]", ChatColors.FileAttr),
-                    });
-                    saveLine.AttachmentUrl = message.AttachmentUrl;
-                    saveLine.AttachmentFileName = imageName;
-                    saveLine.Type = MessageType.Image;
-                    lines.Add(saveLine);
-                }
-                break;
+                case Core.Models.AttachmentKind.Audio:
+                    lines.Add(AttachmentActionLine(pad,
+                        $"♪ [Audio: {attachment.FileName}] [{FormatFileSize(attachment.FileSize)}]",
+                        ChatColors.AudioAttr, attachment));
+                    break;
 
-            case MessageType.Audio:
-                var audioName = message.AttachmentFileName ?? "unknown";
-                var audioSize = FormatFileSize(message.AttachmentFileSize);
-                var audioLine = BuildChatLineColored(time, senderName, senderColor,
-                    $" \u266a [Audio: {audioName}] [{audioSize}]", ChatColors.AudioAttr);
-                audioLine.AttachmentUrl = message.AttachmentUrl;
-                audioLine.AttachmentFileName = audioName;
-                audioLine.Type = MessageType.Audio;
-                lines.Add(audioLine);
-                break;
+                default:
+                    lines.Add(AttachmentActionLine(pad,
+                        $"[File: {attachment.FileName}] [{FormatFileSize(attachment.FileSize)}]",
+                        ChatColors.FileAttr, attachment));
+                    break;
+            }
+        }
 
-            case MessageType.File:
-                var fileName = message.AttachmentFileName ?? "unknown";
-                var fileSize = FormatFileSize(message.AttachmentFileSize);
-                var fileLine = BuildChatLineColored(time, senderName, senderColor,
-                    $" [File: {fileName}] [{fileSize}]", ChatColors.FileAttr);
-                fileLine.AttachmentUrl = message.AttachmentUrl;
-                fileLine.AttachmentFileName = fileName;
-                fileLine.Type = MessageType.File;
-                lines.Add(fileLine);
-                break;
-
-            case MessageType.Text:
-            default:
-                var displayContent = EmojiHelper.ReplaceEmoji(message.Content);
-                var contentLines = displayContent.Split('\n');
-                var firstLine = contentLines[0].TrimEnd('\r');
-                lines.Add(BuildChatLineWithMentions(time, senderName, senderColor, $" {firstLine}"));
-                var indent = new string(' ', $"[{time}] {senderName} ".Length);
-                for (int i = 1; i < contentLines.Length; i++)
-                {
-                    var contText = $"{indent}{contentLines[i].TrimEnd('\r')}";
-                    lines.Add(new ChatLine(ChatColors.SplitMentions(contText)));
-                }
-
-                foreach (var l in lines)
-                    l.ContinuationIndent = indent.Length;
-
-                if (message.Embeds is { Count: > 0 })
-                {
-                    var chatWidth = _chatWidth > 0 ? _chatWidth : 80;
-                    foreach (var embed in message.Embeds)
-                        lines.AddRange(FormatEmbed(embed, indent, chatWidth));
-                }
-                break;
+        // Link embeds (from caption URLs)
+        if (message.Embeds is { Count: > 0 })
+        {
+            var chatWidth = _chatWidth > 0 ? _chatWidth : 80;
+            foreach (var embed in message.Embeds)
+                lines.AddRange(FormatEmbed(embed, indent, chatWidth));
         }
 
         foreach (var line in lines)
@@ -326,7 +317,7 @@ public sealed class ChatMessageManager
             line.SenderUsername = message.SenderUsername;
         }
 
-        if (!string.IsNullOrEmpty(_currentUser) && message.Type == MessageType.Text)
+        if (hasContent && !string.IsNullOrEmpty(_currentUser))
         {
             var pattern = $@"@{Regex.Escape(_currentUser)}\b";
             if (Regex.IsMatch(message.Content, pattern, RegexOptions.IgnoreCase))
@@ -339,6 +330,23 @@ public sealed class ChatMessageManager
         return lines;
     }
 
+    /// <summary>
+    /// Builds a clickable attachment line carrying the metadata the message list uses to
+    /// route activation (play audio, download file, save original image).
+    /// </summary>
+    private static ChatLine AttachmentActionLine(string pad, string text, Attribute color, AttachmentDto attachment)
+    {
+        var line = new ChatLine(new List<ChatSegment>
+        {
+            new(pad, null),
+            new(text, color),
+        });
+        line.AttachmentUrl = attachment.Url;
+        line.AttachmentFileName = attachment.FileName;
+        line.AttachmentKind = attachment.Kind;
+        return line;
+    }
+
     private static ChatLine BuildChatLine(string time, string senderName, Attribute? senderColor, string suffix)
     {
         var segments = new List<ChatSegment>

src/EchoHub.Client/UI/Helpers/DroppedFileParser.cs

@@ -0,0 +1,104 @@
+using System.Text;
+
+namespace EchoHub.Client.UI.Helpers;
+
+/// <summary>
+/// Recognizes a dragged-and-dropped file (or files) that a terminal delivers into the input as an
+/// absolute path. Terminals differ: some paste the whole path at once, others send it character by
+/// character; either way this checks whether the current input text resolves to existing file(s).
+/// </summary>
+public static class DroppedFileParser
+{
+    /// <summary>
+    /// Cheap pre-check so callers only stat the filesystem when the input plausibly holds a path:
+    /// a quoted path, a Windows drive path (<c>X:\</c>/<c>X:/</c>), a UNC path (<c>\\</c>), or a
+    /// POSIX absolute path (<c>/</c>). Normal chat text never starts this way.
+    /// </summary>
+    public static bool LooksLikePath(string text)
+    {
+        var t = text.TrimStart();
+        if (t.Length < 3)
+            return false;
+        if (t[0] is '"' or '/')
+            return true;
+        if (t.StartsWith(@"\\", StringComparison.Ordinal))
+            return true;
+        return char.IsLetter(t[0]) && t[1] == ':' && (t[2] == '\\' || t[2] == '/');
+    }
+
+    /// <summary>
+    /// Returns true when <paramref name="text"/> resolves to one or more existing files.
+    /// Handles a single path (quoted or not, possibly containing spaces) and multiple
+    /// space-separated (optionally quoted) paths. <paramref name="fileExists"/> is injectable
+    /// for testing; production passes <see cref="File.Exists"/>.
+    /// </summary>
+    public static bool TryGetFiles(string text, out List<string> files, Func<string, bool>? fileExists = null)
+    {
+        fileExists ??= File.Exists;
+        files = [];
+
+        var trimmed = text.Trim();
+        if (trimmed.Length < 3 || trimmed.Length > 4096 || trimmed.Contains('\n'))
+            return false;
+
+        // Single path, possibly quoted and/or containing spaces.
+        var unquoted = StripQuotes(trimmed);
+        if (Path.IsPathFullyQualified(unquoted) && fileExists(unquoted))
+        {
+            files.Add(unquoted);
+            return true;
+        }
+
+        // Multiple files: space-separated tokens, each optionally quoted.
+        foreach (var token in TokenizeQuoted(trimmed))
+        {
+            if (!Path.IsPathFullyQualified(token) || !fileExists(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 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();
+    }
+}

src/EchoHub.Client/UI/MainWindow.cs

@@ -40,7 +40,9 @@ public sealed partial class MainWindow : Runnable
     private readonly UserListSource _usersListSource;
     private bool _usersPanelVisible = true;
     private const int UsersPanelWidth = 22;
+    private const string DefaultInputTitle = "Message │ Enter=send │ Ctrl+N=newline │ Tab=complete │ Ctrl+K=search";
     private static readonly Key F2Key = Key.F2;
+    private bool _hasStagedAttachments;
 
     internal static readonly string AppVersion =
         typeof(MainWindow).Assembly.GetName().Version?.ToString(3) ?? "?";
@@ -60,7 +62,7 @@ public sealed partial class MainWindow : Runnable
     private static readonly string[] SlashCommands =
     [
         "/status", "/nick", "/color", "/theme", "/send",
-        "/avatar", "/profile", "/servers", "/join", "/passwd", "/leave",
+        "/avatar", "/profile", "/servers", "/join", "/passwd", "/leave", "/clear", "/downloadpath",
         "/topic", "/users", "/kick", "/ban", "/unban",
         "/mute", "/unmute", "/role", "/nuke", "/test-sound", "/quit", "/help"
     ];
@@ -159,6 +161,11 @@ public sealed partial class MainWindow : Runnable
     /// </summary>
     public event Action<string, string>? OnImageSaveRequested;
 
+    /// <summary>
+    /// Fired when the user presses Delete on the selected message. Parameter is the message id.
+    /// </summary>
+    public event Action<Guid>? OnDeleteMessageRequested;
+
     /// <summary>
     /// Fired when the user activates a username (in userlist or message). Parameter is the username.
     /// </summary>
@@ -240,6 +247,7 @@ public sealed partial class MainWindow : Runnable
         };
         _messageList.Source = new ChatListSource();
         _messageList.Accepting += OnMessageListAccepting;
+        _messageList.KeyDown += OnMessageListKeyDown;
         _messageList.VerticalScrollBar.Scrolled += OnMessageListVerticalScrollBarScrolled;
         _messageList.VerticalScrollBar.Visible = true;
 
@@ -249,7 +257,7 @@ public sealed partial class MainWindow : Runnable
         // Bottom input area
         _inputFrame = new FrameView
         {
-            Title = "Message \u2502 Enter=send \u2502 Ctrl+N=newline \u2502 Tab=complete \u2502 Ctrl+K=search",
+            Title = DefaultInputTitle,
             X = 22,
             Y = Pos.Bottom(_chatFrame),
             Width = Dim.Fill(UsersPanelWidth),
@@ -321,6 +329,27 @@ public sealed partial class MainWindow : Runnable
         KeyDown += OnWindowKeyDown;
     }
 
+    /// <summary>
+    /// Updates the attachment staging indicator shown on the input frame's title.
+    /// Passing an empty list restores the default hint.
+    /// </summary>
+    public void SetStagedAttachments(IReadOnlyList<string> fileNames)
+    {
+        _hasStagedAttachments = fileNames.Count > 0;
+        if (fileNames.Count == 0)
+        {
+            _inputFrame.Title = DefaultInputTitle;
+        }
+        else
+        {
+            var names = string.Join(", ", fileNames);
+            if (names.Length > 60)
+                names = names[..57] + "...";
+            _inputFrame.Title = $"📎 {fileNames.Count} staged: {names} │ Enter=send │ /clear to drop";
+        }
+        _inputFrame.SetNeedsDraw();
+    }
+
     /// <summary>
     /// Applies the currently registered color schemes to all views.
     /// Call after theme changes to refresh colors.
@@ -458,21 +487,21 @@ public sealed partial class MainWindow : Runnable
         // Audio/file attachments take priority
         if (line.AttachmentUrl is not null && line.AttachmentFileName is not null)
         {
-            if (line.Type == MessageType.Audio)
+            if (line.AttachmentKind == AttachmentKind.Audio)
             {
                 OnAudioPlayRequested?.Invoke(line.AttachmentUrl, line.AttachmentFileName);
                 e.Handled = true;
                 return;
             }
 
-            if (line.Type == MessageType.File)
+            if (line.AttachmentKind == AttachmentKind.File)
             {
                 OnFileDownloadRequested?.Invoke(line.AttachmentUrl, line.AttachmentFileName);
                 e.Handled = true;
                 return;
             }
 
-            if (line.Type == MessageType.Image)
+            if (line.AttachmentKind == AttachmentKind.Image)
             {
                 OnImageSaveRequested?.Invoke(line.AttachmentUrl, line.AttachmentFileName);
                 e.Handled = true;
@@ -510,6 +539,32 @@ public sealed partial class MainWindow : Runnable
         }
     }
 
+    private void OnMessageListKeyDown(object? sender, Key e)
+    {
+        if (e.KeyCode != Key.Delete.KeyCode && e.KeyCode != Key.Backspace.KeyCode)
+            return;
+
+        if (_messageList.Source is not ChatListSource source)
+            return;
+
+        var index = _messageList.SelectedItem;
+        if (!index.HasValue || index.Value < 0 || index.Value >= source.Count)
+            return;
+
+        var line = source.GetLine(index.Value);
+        if (line?.MessageId is not { } messageId)
+            return;
+
+        // Server enforces the real permission (own message, or Mod+ over a lower role);
+        // the client just confirms intent and lets the server reject if disallowed.
+        var confirm = MessageBox.Query(_app, "Delete Message",
+            "Delete this message?", "Delete", "Cancel");
+        if (confirm == 0)
+            OnDeleteMessageRequested?.Invoke(messageId);
+
+        e.Handled = true;
+    }
+
     private void OnMessageListVerticalScrollBarScrolled(object? sender, EventArgs<int> e)
     {
         if (_messageList.VerticalScrollBar.Value == 0)
@@ -545,7 +600,9 @@ public sealed partial class MainWindow : Runnable
         else if (e.KeyCode == EnterKey.KeyCode)
         {
             var text = _inputField.Text?.Trim() ?? string.Empty;
-            if (!string.IsNullOrEmpty(text) && !string.IsNullOrEmpty(_messageManager.CurrentChannel))
+            // Send when there's text, or when only attachments are staged (empty caption).
+            if ((!string.IsNullOrEmpty(text) || _hasStagedAttachments)
+                && !string.IsNullOrEmpty(_messageManager.CurrentChannel))
             {
                 OnMessageSubmitted?.Invoke(_messageManager.CurrentChannel, text);
                 _inputField.Text = string.Empty;
@@ -564,9 +621,13 @@ public sealed partial class MainWindow : Runnable
         }
         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");
+            // If a file was copied in the OS file manager, the clipboard holds a file list
+            // (not text) — attach it. Otherwise paste text. This is the reliable path on
+            // Windows Terminal, which never pastes copied files as text.
+            if (ClipboardFiles.TryGetFiles(out var pastedFiles))
+                StageFiles(pastedFiles);
+            else
+                GuardedClipboardAction(() => _inputField.Paste(), "paste");
             e.Handled = true;
         }
         else if (e.KeyCode == CtrlXKey.KeyCode)
@@ -599,42 +660,35 @@ public sealed partial class MainWindow : Runnable
     }
 
     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))
+        // A file dropped onto the terminal is delivered as its absolute path inserted into the
+        // input — often character by character (this Terminal.Gui build has no bracketed-paste
+        // coalescing). As soon as the input resolves to existing file path(s), route them
+        // through /send (which stages them) instead of leaving a raw path to be sent as a message.
+        if (DroppedFileParser.LooksLikePath(text) && DroppedFileParser.TryGetFiles(text, out var droppedFiles)
+            && !string.IsNullOrEmpty(_messageManager.CurrentChannel))
         {
-            var channel = _messageManager.CurrentChannel;
-            if (!string.IsNullOrEmpty(channel))
+            _suppressEmojiReplace = true;
+            try
             {
-                _suppressEmojiReplace = true;
-                try
-                {
-                    _inputField.Text = string.Empty;
-                }
-                finally
-                {
-                    _suppressEmojiReplace = false;
-                }
-
-                foreach (var file in droppedFiles)
-                    OnMessageSubmitted?.Invoke(channel, $"/send \"{file}\"");
-                return;
+                _inputField.Text = string.Empty;
             }
+            finally
+            {
+                _suppressEmojiReplace = false;
+            }
+
+            StageFiles(droppedFiles);
+            return;
         }
 
         var replaced = EmojiHelper.ReplaceEmoji(text);
@@ -695,77 +749,17 @@ public sealed partial class MainWindow : Runnable
     }
 
     /// <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.
+    /// Routes files (from a drop or a file-clipboard paste) through the /send pipeline, which
+    /// stages them; the next Enter sends them with any typed caption.
     /// </summary>
-    private static bool TryGetDroppedFiles(string text, out List<string> files)
+    private void StageFiles(IEnumerable<string> files)
     {
-        files = [];
+        var channel = _messageManager.CurrentChannel;
+        if (string.IsNullOrEmpty(channel))
+            return;
 
-        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();
+        foreach (var file in files)
+            OnMessageSubmitted?.Invoke(channel, $"/send \"{file}\"");
     }
 
     private void OnChatViewportChanged()