diff --git a/Endpoints/HistoryEndpoint.cs b/Endpoints/HistoryEndpoint.cs
index 547a00c..a870f02 100644
--- a/Endpoints/HistoryEndpoint.cs
+++ b/Endpoints/HistoryEndpoint.cs
@@ -21,6 +21,7 @@ public static class HistoryEndpoint
         app.MapGet("/api/archive/{archiveId}", HandleGetArchive);
         app.MapGet("/api/attachments/{messageId}", HandleGetAttachments);
         app.MapPut("/api/messages/{messageId}/mark", HandleToggleMark);
+        app.MapPut("/api/messages/{messageId}/delete", HandleToggleDelete);
         app.MapGet("/api/chains/{chainId}", HandleGetChain);
     }
 
@@ -44,23 +45,24 @@ public static class HistoryEndpoint
         const int messageLimit = 500;
         var beforeStr = ctx.Request.Query["beforeId"].FirstOrDefault();
         var beforeId = long.TryParse(beforeStr, out var b) ? b : 0;
+        var includeDeleted = ctx.Request.Query["includeDeleted"].FirstOrDefault() == "true";
 
-        var totalCount = await db.GetActiveMessageCount(sessionId);
+        var totalCount = await db.GetActiveMessageCount(sessionId, includeDeleted);
 
         List<MessageRecord> messages;
         if (beforeId > 0)
         {
-            messages = await db.GetActiveMessagesBeforeId(sessionId, beforeId, messageLimit);
+            messages = await db.GetActiveMessagesBeforeId(sessionId, beforeId, messageLimit, includeDeleted);
         }
         else
         {
-            messages = await db.GetLatestActiveMessages(sessionId, messageLimit);
+            messages = await db.GetLatestActiveMessages(sessionId, messageLimit, includeDeleted);
         }
 
         // Zähle wie viele Nachrichten es VOR der ältesten geladenen noch gibt
         var oldestLoadedId = messages.Count > 0 ? messages[0].Id : 0;
         var remainingOlder = oldestLoadedId > 0
-            ? await db.GetActiveMessageCountBeforeId(sessionId, oldestLoadedId)
+            ? await db.GetActiveMessageCountBeforeId(sessionId, oldestLoadedId, includeDeleted)
             : 0;
 
         // Nach Chain gruppieren (Reihenfolge beibehalten)
@@ -91,6 +93,7 @@ public static class HistoryEndpoint
         var sessionId = ctx.Request.Query["sessionId"].FirstOrDefault();
         var afterStr = ctx.Request.Query["afterId"].FirstOrDefault();
         var afterId = long.TryParse(afterStr, out var a) ? a : 0;
+        var includeDeleted = ctx.Request.Query["includeDeleted"].FirstOrDefault() == "true";
 
         if (string.IsNullOrEmpty(sessionId) || !await VerifySessionOwner(ctx, db, sessionId))
         {
@@ -98,7 +101,7 @@ public static class HistoryEndpoint
             return;
         }
 
-        var messages = await db.GetActiveMessagesAfterId(sessionId, afterId);
+        var messages = await db.GetActiveMessagesAfterId(sessionId, afterId, includeDeleted: includeDeleted);
         await ctx.Response.WriteAsJsonAsync(messages);
     }
 
@@ -174,6 +177,19 @@ public static class HistoryEndpoint
         await ctx.Response.WriteAsJsonAsync(new { messageId, isMarked });
     }
 
+    private static async Task HandleToggleDelete(HttpContext ctx, DatabaseService db)
+    {
+        var messageIdStr = ctx.Request.RouteValues["messageId"]?.ToString();
+        if (!long.TryParse(messageIdStr, out var messageId))
+        {
+            ctx.Response.StatusCode = 400;
+            return;
+        }
+
+        var deletedOn = await db.ToggleMessageDelete(messageId);
+        await ctx.Response.WriteAsJsonAsync(new { messageId, deletedOn });
+    }
+
     private static async Task HandleGetChain(HttpContext ctx, DatabaseService db)
     {
         var chainId = ctx.Request.RouteValues["chainId"]?.ToString();
diff --git a/Models/MessageRecord.cs b/Models/MessageRecord.cs
index 5e10c48..5397399 100644
--- a/Models/MessageRecord.cs
+++ b/Models/MessageRecord.cs
@@ -14,6 +14,7 @@ public class MessageRecord
     public int AttachmentCount { get; set; } // Anzahl angehängter Dateien
     public string AttachmentNames { get; set; } // JSON-Array mit Dateinamen
     public bool IsMarked { get; set; }       // als wichtig markiert
+    public string DeletedOn { get; set; }    // null = aktiv, sonst Zeitstempel der Löschung
     public string CreatedAt { get; set; }
 }
 
diff --git a/Services/DatabaseService.cs b/Services/DatabaseService.cs
index b96a0e1..b615ce2 100644
--- a/Services/DatabaseService.cs
+++ b/Services/DatabaseService.cs
@@ -146,6 +146,7 @@ public class DatabaseService
         TryAddColumn(conn, "agents", "use_user_info", "INTEGER NOT NULL DEFAULT 1");
         TryAddColumn(conn, "agents", "use_memory", "INTEGER NOT NULL DEFAULT 1");
 
+        TryAddColumn(conn, "messages", "deleted_on", "TEXT");
         TryAddColumn(conn, "agents", "use_web_search", "INTEGER NOT NULL DEFAULT 0");
         TryAddColumn(conn, "agents", "web_search_version", "TEXT DEFAULT ''");
 
@@ -560,57 +561,62 @@ public class DatabaseService
         );
     }
 
-    public async Task<int> GetActiveMessageCount(string sessionId)
+    public async Task<int> GetActiveMessageCount(string sessionId, bool includeDeleted = false)
     {
         using var conn = CreateConnection();
-        return await conn.ExecuteScalarAsync<int>(@"
+        var deletedFilter = includeDeleted ? "" : "AND m.deleted_on IS NULL";
+        return await conn.ExecuteScalarAsync<int>($@"
             SELECT COUNT(*) FROM messages m
             JOIN chains c ON m.chain_id = c.chain_id
-            WHERE c.archive_id IS NULL AND c.session_id = @sessionId",
+            WHERE c.archive_id IS NULL AND c.session_id = @sessionId {deletedFilter}",
             new { sessionId });
     }
 
-    public async Task<List<MessageRecord>> GetLatestActiveMessages(string sessionId, int limit)
+    public async Task<List<MessageRecord>> GetLatestActiveMessages(string sessionId, int limit, bool includeDeleted = false)
     {
         using var conn = CreateConnection();
-        var messages = await conn.QueryAsync<MessageRecord>(@"
+        var deletedFilter = includeDeleted ? "" : "AND m.deleted_on IS NULL";
+        var messages = await conn.QueryAsync<MessageRecord>($@"
             SELECT m.* FROM messages m
             JOIN chains c ON m.chain_id = c.chain_id
-            WHERE c.archive_id IS NULL AND c.session_id = @sessionId
+            WHERE c.archive_id IS NULL AND c.session_id = @sessionId {deletedFilter}
             ORDER BY m.id DESC LIMIT @limit",
             new { sessionId, limit });
         return messages.Reverse().ToList();
     }
 
-    public async Task<int> GetActiveMessageCountBeforeId(string sessionId, long beforeId)
+    public async Task<int> GetActiveMessageCountBeforeId(string sessionId, long beforeId, bool includeDeleted = false)
     {
         using var conn = CreateConnection();
-        return await conn.ExecuteScalarAsync<int>(@"
+        var deletedFilter = includeDeleted ? "" : "AND m.deleted_on IS NULL";
+        return await conn.ExecuteScalarAsync<int>($@"
             SELECT COUNT(*) FROM messages m
             JOIN chains c ON m.chain_id = c.chain_id
-            WHERE m.id < @beforeId AND c.archive_id IS NULL AND c.session_id = @sessionId",
+            WHERE m.id < @beforeId AND c.archive_id IS NULL AND c.session_id = @sessionId {deletedFilter}",
             new { sessionId, beforeId });
     }
 
-    public async Task<List<MessageRecord>> GetActiveMessagesBeforeId(string sessionId, long beforeId, int limit)
+    public async Task<List<MessageRecord>> GetActiveMessagesBeforeId(string sessionId, long beforeId, int limit, bool includeDeleted = false)
     {
         using var conn = CreateConnection();
-        var messages = await conn.QueryAsync<MessageRecord>(@"
+        var deletedFilter = includeDeleted ? "" : "AND m.deleted_on IS NULL";
+        var messages = await conn.QueryAsync<MessageRecord>($@"
             SELECT m.* FROM messages m
             JOIN chains c ON m.chain_id = c.chain_id
-            WHERE m.id < @beforeId AND c.archive_id IS NULL AND c.session_id = @sessionId
+            WHERE m.id < @beforeId AND c.archive_id IS NULL AND c.session_id = @sessionId {deletedFilter}
             ORDER BY m.id DESC LIMIT @limit",
             new { sessionId, beforeId, limit });
         return messages.Reverse().ToList();
     }
 
-    public async Task<IEnumerable<MessageRecord>> GetActiveMessagesAfterId(string sessionId, long afterId, int limit = 200)
+    public async Task<IEnumerable<MessageRecord>> GetActiveMessagesAfterId(string sessionId, long afterId, int limit = 200, bool includeDeleted = false)
     {
         using var conn = CreateConnection();
-        return await conn.QueryAsync<MessageRecord>(@"
+        var deletedFilter = includeDeleted ? "" : "AND m.deleted_on IS NULL";
+        return await conn.QueryAsync<MessageRecord>($@"
             SELECT m.* FROM messages m
             JOIN chains c ON m.chain_id = c.chain_id
-            WHERE m.id > @afterId AND c.archive_id IS NULL AND c.session_id = @sessionId
+            WHERE m.id > @afterId AND c.archive_id IS NULL AND c.session_id = @sessionId {deletedFilter}
             ORDER BY m.id LIMIT @limit",
             new { sessionId, afterId, limit });
     }
@@ -628,6 +634,31 @@ public class DatabaseService
             new { messageId });
     }
 
+    // ── Message Deletion ──
+
+    public async Task<string> ToggleMessageDelete(long messageId)
+    {
+        using var conn = CreateConnection();
+        var current = await conn.ExecuteScalarAsync<string>(
+            "SELECT deleted_on FROM messages WHERE id = @messageId", new { messageId });
+        string newValue;
+        if (current == null)
+        {
+            newValue = DateTime.UtcNow.ToString("o");
+            await conn.ExecuteAsync(
+                "UPDATE messages SET deleted_on = @newValue WHERE id = @messageId",
+                new { messageId, newValue });
+        }
+        else
+        {
+            newValue = null;
+            await conn.ExecuteAsync(
+                "UPDATE messages SET deleted_on = NULL WHERE id = @messageId",
+                new { messageId });
+        }
+        return newValue;
+    }
+
     public async Task<IEnumerable<MessageRecord>> GetMarkedMessages(string sessionId)
     {
         using var conn = CreateConnection();
diff --git a/TODO.md b/TODO.md
index d5a6acf..816c276 100644
--- a/TODO.md
+++ b/TODO.md
@@ -7,14 +7,13 @@
 - [x] Agents-Formular (nur beim Bearbeiten von vorhandenen Agent): Button der das File-Explorer Modal öffnet bei dem ich den Agent-Ordner sehe.
 - [x] Chat: Maximal 500 Nachrichten laden. Dauert sonst zu lange und der Browser wird langsam
 - [x] User-Management: Tabelle in Datenbank mit username / password. Wenn kein User vorhanden: dann admin mit password "admin" anlegen
-- [ ] Neuer Message-Tag: `[canvas:<title>:<height (optional)>]...[/canvas]`
 - [x] Websearch Tool
 - [x] Anfrage/Stream abbrechen
 - [x] Telegram-Intergration
 - [x] Refactoring: Agent/Session-Einstellungen, die den System-Prompt bzw. das Tool Use bearbeiten
 - [ ] Cronjobs: Planung, ob cron von Debian/Linux verwendet werden soll, oder ein eigener Worker/Service in der App selbst, der das übernimmt
 - [x] Weiteres Modell hinzufügen: "Haiku 4.5"
-- [ ] Weitere Tools: Glob? Search?
+- [ ] Weitere Tools: Glob? Search? Todo List?
 
 ## Bugs
 - [x] Wenn gerade gestreamt wird und man refreshed die Seite, dann verliert das Frontend den Status "Streaming..." und ich kann eine Nachricht schreiben, obwohl das nicht möglich sein sollte
@@ -33,7 +32,15 @@
 - [x] File Explorer: CodeMirror lässt sich horizontal nicht scroll
 - [ ] Chat: Datum und Uhrzeit bei den Nachrichten anzeigen (Format: dd.MM.yyyy HH:mm:ss)
 - [x] Dashboard: Menu-Dropdown bei Cards sind abgeschnitten wenn die Card-Höhe nicht ausreicht (logisch, weil das Menu-Dropdown ein Child von der Card ist)
+- [ ] Auto-scrolling deaktivieren, wenn man weiterhoch gescrollt hat, und er wieder fortsetzen wenn man ganz nach unten gescrollt hat
 
 ## Ideas / Backlog
 - [ ] Memory: Embedding-Modell für semantische Suche über Memory-Dateien (Vektor-basiert + BM25 Hybrid Search)
 - [ ] Subagents: Möglichkeit Subagents zu starten und zu orchestrieren
+
+## Features aus Devy übernehmen
+- [ ] 💬 Typing-Indicator - Animierter Indikator statt statischem "denkt nach..."
+- [ ] 🎨 Chat-Hintergründe - Benutzerdefinierte Hintergründe pro Session
+- [ ] 👤 User-Management - Admin-only: Benutzer CRUD, Login-as-User, Default-Pfade
+- [ ] 🖥️ Windows Desktop App - WPF + WebView2 Wrapper mit konfigurierbarer URL
+- [ ] 🎨 Canvas - HTML/CSS/JS inline rendern in sandboxed iframes mit Resize und Source-View (Message-Tag: `[canvas:<title>:<height (optional)>]...[/canvas]`)
diff --git a/wwwroot/css/chat.css b/wwwroot/css/chat.css
index fd4d230..4caab6c 100644
--- a/wwwroot/css/chat.css
+++ b/wwwroot/css/chat.css
@@ -280,6 +280,7 @@
 }
 
 .msg-reply-btn,
+.msg-delete-btn,
 .msg-mark-btn {
   position: absolute;
   top: var(--badge-spacing);
@@ -294,6 +295,10 @@
 }
 
 .msg-reply-btn {
+  right: calc(var(--badge-spacing) + 4em + var(--badge-spacing) * 2);
+}
+
+.msg-delete-btn {
   right: calc(var(--badge-spacing) + 2em + var(--badge-spacing));
 }
 
@@ -302,11 +307,13 @@
 }
 
 .msg:hover .msg-reply-btn,
+.msg:hover .msg-delete-btn,
 .msg:hover .msg-mark-btn {
   opacity: var(--semi-transparent);
 }
 
 .msg-reply-btn:hover,
+.msg-delete-btn:hover,
 .msg-mark-btn:hover {
   opacity: 1 !important;
 }
@@ -316,12 +323,30 @@
   color: var(--warning);
 }
 
+.msg-delete-btn.deleted {
+  opacity: 1 !important;
+  color: var(--dangerous);
+}
+
 /* Markierte Nachrichten */
 
 .msg.marked {
   border-left: 3px solid var(--warning);
 }
 
+/* Gelöschte Nachrichten */
+
+.msg.msg-deleted {
+  opacity: 0.45;
+  text-decoration: line-through;
+  text-decoration-color: var(--dangerous);
+  border-left: 3px solid var(--dangerous);
+}
+
+.msg.msg-deleted-hidden {
+  display: none;
+}
+
 /* Reply Quote in User Bubble */
 
 .reply-quote {
diff --git a/wwwroot/css/form.css b/wwwroot/css/form.css
index e736b40..d7465be 100644
--- a/wwwroot/css/form.css
+++ b/wwwroot/css/form.css
@@ -228,3 +228,48 @@ label.skill-item {
   background: var(--dangerous);
   color: var(--f1-bg);
 }
+
+/* Toggle Switch */
+
+.toggle-switch {
+  position: relative;
+  display: inline-block;
+  width: 2.4em;
+  height: 1.4em;
+  cursor: pointer;
+}
+
+.toggle-switch input {
+  opacity: 0;
+  width: 0;
+  height: 0;
+}
+
+.toggle-slider {
+  position: absolute;
+  inset: 0;
+  background: var(--f2-border);
+  border-radius: 1em;
+  transition: background var(--transition-duration);
+}
+
+.toggle-slider::before {
+  content: '';
+  position: absolute;
+  width: 1em;
+  height: 1em;
+  left: .2em;
+  top: .2em;
+  background: var(--f1-bg);
+  border-radius: 50%;
+  transition: transform var(--transition-duration);
+}
+
+.toggle-switch input:checked + .toggle-slider {
+  background: var(--secondary);
+}
+
+.toggle-switch input:checked + .toggle-slider::before {
+  transform: translateX(1em);
+}
+
diff --git a/wwwroot/index.html b/wwwroot/index.html
index 9835cb5..1c48b4f 100644
--- a/wwwroot/index.html
+++ b/wwwroot/index.html
@@ -273,6 +273,18 @@
               </select>
             </div>
           </div>
+          <div class="setting-row">
+            <div class="setting-info">
+              <label>Gelöschte Nachrichten</label>
+              <span class="setting-hint">Gelöschte Nachrichten durchgestrichen anzeigen (werden nicht an die KI gesendet)</span>
+            </div>
+            <div class="setting-control">
+              <label class="toggle-switch">
+                <input type="checkbox" id="settingShowDeletedMessages">
+                <span class="toggle-slider"></span>
+              </label>
+            </div>
+          </div>
         </section>
         <section id="settingsBackupSection" class="settings-section" style="display:none">
           <h2>Daten</h2>
diff --git a/wwwroot/js/api.js b/wwwroot/js/api.js
index d1c6f6e..b06757e 100644
--- a/wwwroot/js/api.js
+++ b/wwwroot/js/api.js
@@ -85,15 +85,18 @@ async function apiDeleteAgent(agentId) {
   return fetch(`/api/agents/${agentId}`, { method: 'DELETE' });
 }
 
-async function apiHistory(sessionId, beforeId) {
+async function apiHistory(sessionId, beforeId, includeDeleted = false) {
   let url = `/api/history?sessionId=${sessionId}`;
   if (beforeId) url += `&beforeId=${beforeId}`;
+  if (includeDeleted) url += `&includeDeleted=true`;
   const resp = await fetch(url);
   return resp.json();
 }
 
-async function apiHistoryPoll(sessionId, afterId) {
-  const resp = await fetch(`/api/history/poll?sessionId=${sessionId}&afterId=${afterId}`);
+async function apiHistoryPoll(sessionId, afterId, includeDeleted = false) {
+  let url = `/api/history/poll?sessionId=${sessionId}&afterId=${afterId}`;
+  if (includeDeleted) url += `&includeDeleted=true`;
+  const resp = await fetch(url);
   return resp.json();
 }
 
@@ -186,6 +189,11 @@ async function apiToggleMessageMark(messageId) {
   return resp.json();
 }
 
+async function apiToggleMessageDelete(messageId) {
+  const resp = await fetch(`/api/messages/${messageId}/delete`, { method: 'PUT' });
+  return resp.json();
+}
+
 async function apiGitStatus(sessionId) {
   const resp = await fetch(`/api/sessions/${sessionId}/git-status`);
   if (!resp.ok) return null;
diff --git a/wwwroot/js/history.js b/wwwroot/js/history.js
index 8dba9df..ec35aef 100644
--- a/wwwroot/js/history.js
+++ b/wwwroot/js/history.js
@@ -10,7 +10,7 @@ async function loadHistory() {
   try {
     const sid = getCurrentSessionId();
 
-    const data = await apiHistory(sid);
+    const data = await apiHistory(sid, null, isDeletedVisible());
     const entries = data.entries || [];
 
     // Älteste geladene Message-ID merken für Nachladen
@@ -51,7 +51,7 @@ async function loadOlderMessages() {
 
   try {
     const sid = getCurrentSessionId();
-    const data = await apiHistory(sid, _oldestLoadedMessageId);
+    const data = await apiHistory(sid, _oldestLoadedMessageId, isDeletedVisible());
     const entries = data.entries || [];
 
     _hasMoreOlderMessages = data.hasMore;
@@ -146,11 +146,13 @@ function _renderMessagesIntoFragment(fragment, msgs) {
       case 'text':
         if (msg.role === 'user') {
           div.className = 'msg user markdown' + (msg.isMarked ? ' marked' : '');
+          if (msg.deletedOn) div.classList.add(isDeletedVisible() ? 'msg-deleted' : 'msg-deleted-hidden');
           div.dataset.role = 'user';
           div.dataset.timestamp = msg.createdAt || '';
           if (msg.id) div.dataset.messageId = msg.id;
           renderUserContent(div, msg.content);
           _addReplyButton(div);
+          _addDeleteButton(div, msg.id, msg.deletedOn);
           _addMarkButton(div, msg.id, msg.isMarked);
           fragment.appendChild(div);
           if (msg.attachmentCount > 0) {
@@ -167,12 +169,14 @@ function _renderMessagesIntoFragment(fragment, msgs) {
           }
         } else if (msg.role === 'assistant') {
           div.className = 'msg assistant markdown' + (msg.isMarked ? ' marked' : '');
+          if (msg.deletedOn) div.classList.add(isDeletedVisible() ? 'msg-deleted' : 'msg-deleted-hidden');
           div.dataset.role = 'assistant';
           div.dataset.timestamp = msg.createdAt || '';
           if (msg.id) div.dataset.messageId = msg.id;
           div.innerHTML = renderMarkdown(msg.content);
           parseFluentEmojis(div);
           _addReplyButton(div);
+          _addDeleteButton(div, msg.id, msg.deletedOn);
           _addMarkButton(div, msg.id, msg.isMarked);
           fragment.appendChild(div);
         }
@@ -215,12 +219,12 @@ function renderMessages(msgs, addToConversation) {
     switch (msg.type) {
       case 'text':
         if (msg.role === 'user') {
-          addUserBubble(msg.content, false, msg.createdAt, msg.id, msg.isMarked);
+          addUserBubble(msg.content, false, msg.createdAt, msg.id, msg.isMarked, msg.deletedOn);
           if (msg.attachmentCount > 0) addAttachmentIndicator(msg.id, msg.attachmentCount, msg.attachmentNames);
-          if (addToConversation) messages.push({ role: 'user', content: msg.content });
+          if (addToConversation && !msg.deletedOn) messages.push({ role: 'user', content: msg.content });
         } else if (msg.role === 'assistant') {
-          addAssistantBubble(msg.content, msg.createdAt, msg.id, msg.isMarked);
-          if (addToConversation) messages.push({ role: 'assistant', content: msg.content });
+          addAssistantBubble(msg.content, msg.createdAt, msg.id, msg.isMarked, msg.deletedOn);
+          if (addToConversation && !msg.deletedOn) messages.push({ role: 'assistant', content: msg.content });
         }
         break;
 
@@ -388,7 +392,7 @@ async function pollHistory(force = false) {
   _pollLock = true;
 
   try {
-    const newMessages = await apiHistoryPoll(getCurrentSessionId(), lastKnownMessageId);
+    const newMessages = await apiHistoryPoll(getCurrentSessionId(), lastKnownMessageId, isDeletedVisible());
     if (newMessages.length > 0) {
       renderMessages(newMessages, true);
       scrollDown();
diff --git a/wwwroot/js/pages/settings-page.js b/wwwroot/js/pages/settings-page.js
index 4e43017..252fa63 100644
--- a/wwwroot/js/pages/settings-page.js
+++ b/wwwroot/js/pages/settings-page.js
@@ -5,7 +5,8 @@ const SETTINGS_KEY = 'settings';
 const SETTINGS_DEFAULTS = {
   pageWidth: 900,
   toolCallDisplay: 'modifications', // 'all' | 'modifications' | 'hidden'
-  chainMetaDisplay: 'sometimes'     // 'always' | 'sometimes' | 'never'
+  chainMetaDisplay: 'sometimes',    // 'always' | 'sometimes' | 'never'
+  showDeletedMessages: false
 };
 
 function loadSettings() {
@@ -38,6 +39,7 @@ registerPage('settings', {
     const display = document.getElementById('settingPageWidthValue');
     const toolCallSelect = document.getElementById('settingToolCallDisplay');
     const chainMetaSelect = document.getElementById('settingChainMetaDisplay');
+    const showDeletedToggle = document.getElementById('settingShowDeletedMessages');
     const resetBtn = document.getElementById('settingsResetBtn');
     const backupSection = document.getElementById('settingsBackupSection');
     const telegramSection = document.getElementById('settingsTelegramSection');
@@ -53,6 +55,7 @@ registerPage('settings', {
     display.textContent = s.pageWidth + 'px';
     toolCallSelect.value = s.toolCallDisplay;
     chainMetaSelect.value = s.chainMetaDisplay;
+    showDeletedToggle.checked = s.showDeletedMessages;
 
     slider.addEventListener('input', () => {
       display.textContent = slider.value + 'px';
@@ -77,6 +80,12 @@ registerPage('settings', {
       saveSettings(s);
     });
 
+    showDeletedToggle.addEventListener('change', () => {
+      const s = loadSettings();
+      s.showDeletedMessages = showDeletedToggle.checked;
+      saveSettings(s);
+    });
+
     const backupBtn = document.getElementById('settingsBackupBtn');
     if (backupBtn) backupBtn.addEventListener('click', async () => {
       backupBtn.disabled = true;
@@ -100,6 +109,7 @@ registerPage('settings', {
       display.textContent = SETTINGS_DEFAULTS.pageWidth + 'px';
       toolCallSelect.value = SETTINGS_DEFAULTS.toolCallDisplay;
       chainMetaSelect.value = SETTINGS_DEFAULTS.chainMetaDisplay;
+      showDeletedToggle.checked = SETTINGS_DEFAULTS.showDeletedMessages;
     });
 
     function initTelegramSection() {
diff --git a/wwwroot/js/ui.js b/wwwroot/js/ui.js
index 646802d..3ead21a 100644
--- a/wwwroot/js/ui.js
+++ b/wwwroot/js/ui.js
@@ -115,6 +115,46 @@ function truncate(s, max) {
   return s && s.length > max ? s.substring(0, max) + '...' : (s || '');
 }
 
+// ── Delete Button ──
+
+function _addDeleteButton(div, messageId, deletedOn) {
+  if (!messageId) return;
+  const isDeleted = !!deletedOn;
+  const btn = document.createElement('button');
+  btn.className = 'msg-delete-btn icon-btn' + (isDeleted ? ' deleted' : '');
+  btn.innerHTML = '<i class="fa fa-trash-o"></i>';
+  btn.title = isDeleted ? 'Löschung aufheben' : 'Nachricht löschen';
+  btn.addEventListener('click', async (e) => {
+    e.stopPropagation();
+    try {
+      const result = await apiToggleMessageDelete(messageId);
+      const nowDeleted = !!result.deletedOn;
+      btn.classList.toggle('deleted', nowDeleted);
+      btn.title = nowDeleted ? 'Löschung aufheben' : 'Nachricht löschen';
+      if (nowDeleted && !isDeletedVisible()) {
+        // Nachricht ausblenden
+        div.classList.add('msg-deleted-hidden');
+      } else {
+        div.classList.remove('msg-deleted-hidden');
+        div.classList.toggle('msg-deleted', nowDeleted);
+      }
+    } catch (err) {
+      console.error('Delete toggle failed:', err);
+    }
+  });
+  // Nach dem Reply-Button einfügen
+  const replyBtn = div.querySelector('.msg-reply-btn');
+  if (replyBtn) {
+    replyBtn.after(btn);
+  } else {
+    div.prepend(btn);
+  }
+}
+
+function isDeletedVisible() {
+  return loadSettings().showDeletedMessages === true;
+}
+
 // ── Mark Button ──
 
 function _addMarkButton(div, messageId, isMarked) {
@@ -134,11 +174,17 @@ function _addMarkButton(div, messageId, isMarked) {
       console.error('Mark toggle failed:', err);
     }
   });
-  const replyBtn = div.querySelector('.msg-reply-btn');
-  if (replyBtn) {
-    replyBtn.after(btn);
+  // Nach dem Delete-Button einfügen (oder nach Reply-Button, oder am Anfang)
+  const deleteBtn = div.querySelector('.msg-delete-btn');
+  if (deleteBtn) {
+    deleteBtn.after(btn);
   } else {
-    div.prepend(btn);
+    const replyBtn = div.querySelector('.msg-reply-btn');
+    if (replyBtn) {
+      replyBtn.after(btn);
+    } else {
+      div.prepend(btn);
+    }
   }
 }
 
@@ -238,23 +284,26 @@ function _renderUserTextContent(container, raw) {
   parseFluentEmojis(wrap);
 }
 
-function addUserBubble(text, streamed = false, timestamp = '', messageId = null, isMarked = false) {
+function addUserBubble(text, streamed = false, timestamp = '', messageId = null, isMarked = false, deletedOn = null) {
   const div = document.createElement('div');
   div.className = 'msg user markdown' + (isMarked ? ' marked' : '');
+  if (deletedOn) div.classList.add(isDeletedVisible() ? 'msg-deleted' : 'msg-deleted-hidden');
   div.dataset.role = 'user';
   div.dataset.timestamp = timestamp || new Date().toISOString();
   if (messageId) div.dataset.messageId = messageId;
   if (streamed) div.classList.add('streamed');
   renderUserContent(div, text);
   _addReplyButton(div);
+  _addDeleteButton(div, messageId, deletedOn);
   _addMarkButton(div, messageId, isMarked);
   chatEl().appendChild(div);
   scrollDown();
 }
 
-function addAssistantBubble(text, timestamp = '', messageId = null, isMarked = false) {
+function addAssistantBubble(text, timestamp = '', messageId = null, isMarked = false, deletedOn = null) {
   const div = document.createElement('div');
   div.className = 'msg assistant markdown' + (isMarked ? ' marked' : '');
+  if (deletedOn) div.classList.add(isDeletedVisible() ? 'msg-deleted' : 'msg-deleted-hidden');
   div.dataset.role = 'assistant';
   div.dataset.timestamp = timestamp || new Date().toISOString();
   if (messageId) div.dataset.messageId = messageId;
@@ -262,6 +311,7 @@ function addAssistantBubble(text, timestamp = '', messageId = null, isMarked = f
   parseFluentEmojis(div);
   wrapKreaGalleries(div);
   _addReplyButton(div);
+  _addDeleteButton(div, messageId, deletedOn);
   _addMarkButton(div, messageId, isMarked);
   chatEl().appendChild(div);
   scrollDown();