diff --git a/public/app.js b/public/app.js
index dcbc378..f8957d0 100644
--- a/public/app.js
+++ b/public/app.js
@@ -2,7 +2,7 @@
 (function () {
   'use strict';
 
-  const ASSET_VERSION = '20260621-cross-reply-collapse-last-section-offset';
+  const ASSET_VERSION = '20260622-queued-send';
   const WS_URL = `${location.protocol === 'https:' ? 'wss' : 'ws'}://${location.host}/ws`;
   const RENDER_DEBOUNCE = 100;
   const COMPOSER_SUGGESTION_DEBOUNCE = 120;
@@ -196,8 +196,11 @@
   let pendingSessionSwitchRequest = null;
   let skipDeleteConfirm = localStorage.getItem('cc-web-skip-delete-confirm') === '1';
   let pendingInitialSessionLoad = false;
+  let initialSessionListHandled = false;
   let noteMode = false;
   let noteDraftSeq = 0;
+  let queuedMessageSeq = 0;
+  let queuedMessageDrainTimer = null;
   let isReloadingMcp = false;
   let sessionSearchQuery = '';
   const collapsedProjectKeys = (() => {
@@ -217,6 +220,7 @@
     }
   })();
   const pendingNotesByTarget = new Map();
+  const queuedMessagesByTarget = new Map();
   const userMessageIndex = new Map();
   const expandedOldSessionGroups = new Set();
   document.documentElement.dataset.dividerTime = showAgentDividerTime ? 'show' : 'hide';
@@ -261,6 +265,7 @@
   const msgInput = $('#msg-input');
   const inputWrapper = msgInput.closest('.input-wrapper');
   const noteModeBtn = $('#note-mode-btn');
+  const queueSendBtn = $('#queue-send-btn');
   const sendBtn = $('#send-btn');
   const abortBtn = $('#abort-btn');
   const cmdMenu = $('#cmd-menu');
@@ -301,6 +306,22 @@
     return currentSessionId || getDraftNoteKey(agent);
   }
 
+  function getSessionQueueKey(sessionId) {
+    return sessionId ? `session:${sessionId}` : '';
+  }
+
+  function getDraftQueueKey(agent = currentAgent) {
+    return `queue:${getDraftNoteKey(agent)}`;
+  }
+
+  function getCurrentQueueKey(agent = currentAgent) {
+    return currentSessionId ? getSessionQueueKey(currentSessionId) : getDraftQueueKey(agent);
+  }
+
+  function supportsQueuedSend(agent = currentAgent) {
+    return isCodexAppAgent(agent);
+  }
+
   function getNotesForKey(key, create = true) {
     if (!key) return [];
     if (!pendingNotesByTarget.has(key)) {
@@ -319,6 +340,24 @@
     if (!notes || notes.length === 0) pendingNotesByTarget.delete(key);
   }
 
+  function getQueueForKey(key, create = true) {
+    if (!key) return [];
+    if (!queuedMessagesByTarget.has(key)) {
+      if (!create) return [];
+      queuedMessagesByTarget.set(key, []);
+    }
+    return queuedMessagesByTarget.get(key);
+  }
+
+  function getCurrentQueue(create = true) {
+    return getQueueForKey(getCurrentQueueKey(), create);
+  }
+
+  function cleanupQueueKey(key) {
+    const queue = queuedMessagesByTarget.get(key);
+    if (!queue || queue.length === 0) queuedMessagesByTarget.delete(key);
+  }
+
   function migratePendingNotesToSession(sessionId, agent = currentAgent) {
     if (!sessionId) return;
     const draftKey = getDraftNoteKey(agent);
@@ -329,6 +368,16 @@
     pendingNotesByTarget.delete(draftKey);
   }
 
+  function migrateQueuedMessagesToSession(sessionId, agent = currentAgent) {
+    if (!sessionId) return;
+    const draftKey = getDraftQueueKey(agent);
+    const draftQueue = queuedMessagesByTarget.get(draftKey);
+    if (!draftQueue || draftQueue.length === 0) return;
+    const sessionQueue = getQueueForKey(getSessionQueueKey(sessionId), true);
+    sessionQueue.push(...draftQueue);
+    queuedMessagesByTarget.delete(draftKey);
+  }
+
   function updateGenerationControls() {
     const noteActive = !!noteMode;
     const allowRuntimeInsert = isGenerating && isCodexAppAgent(currentAgent) && !noteActive;
@@ -339,6 +388,14 @@
       sendBtn.setAttribute('aria-label', sendLabel);
       sendBtn.hidden = isGenerating ? !(noteActive || allowRuntimeInsert) : false;
     }
+    if (queueSendBtn) {
+      const queueAvailable = noteActive && supportsQueuedSend();
+      const queueLabel = isGenerating || currentSessionRunning ? '排队发送' : '排队发送（空闲时将立即发送）';
+      queueSendBtn.hidden = !queueAvailable;
+      queueSendBtn.disabled = !queueAvailable;
+      queueSendBtn.title = queueLabel;
+      queueSendBtn.setAttribute('aria-label', queueLabel);
+    }
     if (abortBtn) {
       abortBtn.hidden = !isGenerating;
     }
@@ -398,18 +455,69 @@
     editBtn.addEventListener('click', () => beginEditPendingNote(note.id));
     deleteBtn.addEventListener('click', () => removePendingNote(note.id));
     sendNoteBtn.addEventListener('click', () => sendPendingNote(note.id));
-    actions.append(editBtn, deleteBtn, sendNoteBtn);
+    actions.append(editBtn, deleteBtn);
+    if (supportsQueuedSend()) {
+      const queueNoteBtn = createNoteActionButton('queue', '排队', '加入自动发送队列');
+      queueNoteBtn.addEventListener('click', () => queuePendingNote(note.id));
+      actions.appendChild(queueNoteBtn);
+    }
+    actions.appendChild(sendNoteBtn);
 
     bubble.append(meta, text, actions);
     div.append(avatar, bubble);
     return div;
   }
 
+  function createQueuedMessageElement(message, index, total) {
+    const div = document.createElement('div');
+    div.className = 'pending-note queued-message';
+    div.dataset.queueId = message.id;
+
+    const avatar = document.createElement('div');
+    avatar.className = 'note-avatar queue-avatar';
+    avatar.textContent = 'Q';
+
+    const bubble = document.createElement('div');
+    bubble.className = 'note-bubble queue-bubble';
+
+    const meta = document.createElement('div');
+    meta.className = 'note-meta queue-meta';
+    const waitLabel = isGenerating || currentSessionRunning ? '等待本轮结束' : '即将发送';
+    meta.textContent = `队列 · 第 ${index + 1}/${total} 条 · ${waitLabel}`;
+
+    const text = document.createElement('div');
+    text.className = 'note-text';
+    text.textContent = message.text;
+
+    const actions = document.createElement('div');
+    actions.className = 'note-actions';
+
+    const upBtn = createNoteActionButton('move-up', '上移', '上移一位');
+    upBtn.disabled = index <= 0;
+    upBtn.addEventListener('click', () => moveQueuedMessage(message.id, -1));
+
+    const downBtn = createNoteActionButton('move-down', '下移', '下移一位');
+    downBtn.disabled = index >= total - 1;
+    downBtn.addEventListener('click', () => moveQueuedMessage(message.id, 1));
+
+    const editBtn = createNoteActionButton('edit', '修改');
+    editBtn.addEventListener('click', () => beginEditQueuedMessage(message.id));
+
+    const deleteBtn = createNoteActionButton('delete', '删除');
+    deleteBtn.addEventListener('click', () => removeQueuedMessage(message.id));
+
+    actions.append(upBtn, downBtn, editBtn, deleteBtn);
+    bubble.append(meta, text, actions);
+    div.append(avatar, bubble);
+    return div;
+  }
+
   function renderPendingNotes(options = {}) {
     if (!pendingNotesTray) return;
     pendingNotesTray.innerHTML = '';
     const notes = getCurrentNotes(false);
-    if (!notes || notes.length === 0) {
+    const queuedMessages = getCurrentQueue(false);
+    if ((!notes || notes.length === 0) && (!queuedMessages || queuedMessages.length === 0)) {
       pendingNotesTray.hidden = true;
       if (options.updateScrollbar !== false) updateScrollbar();
       return;
@@ -417,6 +525,9 @@
 
     const frag = document.createDocumentFragment();
     notes.forEach((note) => frag.appendChild(createPendingNoteElement(note)));
+    queuedMessages.forEach((message, index) => {
+      frag.appendChild(createQueuedMessageElement(message, index, queuedMessages.length));
+    });
     pendingNotesTray.appendChild(frag);
     pendingNotesTray.hidden = false;
     if (options.scrollIntoView !== false && options.scroll !== false) {
@@ -454,6 +565,91 @@
     return true;
   }
 
+  function getQueuedMessageValidationError(content) {
+    if (!supportsQueuedSend()) return '排队发送仅支持 Codex App。';
+    if (!String(content || '').trim()) return '排队内容不能为空。';
+    if (String(content || '').trim().startsWith('/')) return '排队发送暂不支持 slash 指令。';
+    return '';
+  }
+
+  function addQueuedMessage(text, options = {}) {
+    const content = String(text || '').trim();
+    const validationError = getQueuedMessageValidationError(content);
+    if (validationError) {
+      appendError(validationError);
+      return false;
+    }
+    const message = {
+      id: `queued-${Date.now().toString(36)}-${++queuedMessageSeq}`,
+      text: content,
+      createdAt: Date.now(),
+    };
+    getCurrentQueue(true).push(message);
+    if (options.render !== false) renderPendingNotes();
+    scheduleQueuedMessageDrain();
+    return true;
+  }
+
+  function queueMessageFromInput() {
+    const text = msgInput.value.trim();
+    if (!text || isBlockingSessionLoad()) return;
+    hideCmdMenu();
+    hideOptionPicker();
+    if (pendingAttachments.length > 0) {
+      appendError('排队发送暂不支持图片附件，请先移除图片。');
+      return;
+    }
+    if (addQueuedMessage(text)) {
+      msgInput.value = '';
+      autoResize();
+    }
+  }
+
+  function queuePendingNote(noteId) {
+    const found = findPendingNote(noteId);
+    if (!found) return;
+    const text = String(found.note.text || '').trim();
+    const validationError = getQueuedMessageValidationError(text);
+    if (validationError) {
+      appendError(validationError);
+      return;
+    }
+    dropPendingNote(noteId);
+    addQueuedMessage(text, { render: false });
+    renderPendingNotes();
+  }
+
+  function findQueuedMessage(queueId) {
+    const key = getCurrentQueueKey();
+    const queue = getQueueForKey(key, false);
+    const index = queue.findIndex((message) => message.id === queueId);
+    if (index === -1) return null;
+    return { key, queue, index, message: queue[index] };
+  }
+
+  function dropQueuedMessage(queueId) {
+    const found = findQueuedMessage(queueId);
+    if (!found) return null;
+    const [message] = found.queue.splice(found.index, 1);
+    cleanupQueueKey(found.key);
+    return message;
+  }
+
+  function removeQueuedMessage(queueId) {
+    if (!dropQueuedMessage(queueId)) return;
+    renderPendingNotes({ scroll: false });
+  }
+
+  function moveQueuedMessage(queueId, delta) {
+    const found = findQueuedMessage(queueId);
+    if (!found) return;
+    const nextIndex = found.index + delta;
+    if (nextIndex < 0 || nextIndex >= found.queue.length) return;
+    const [message] = found.queue.splice(found.index, 1);
+    found.queue.splice(nextIndex, 0, message);
+    renderPendingNotes({ scroll: false });
+  }
+
   function removePendingNote(noteId) {
     if (!dropPendingNote(noteId)) return;
     renderPendingNotes({ scroll: false });
@@ -522,6 +718,65 @@
     });
   }
 
+  function beginEditQueuedMessage(queueId) {
+    const found = findQueuedMessage(queueId);
+    if (!found) return;
+    const queueEl = pendingNotesTray?.querySelector(`.queued-message[data-queue-id="${queueId}"]`);
+    const bubble = queueEl?.querySelector('.note-bubble');
+    if (!bubble) return;
+
+    bubble.classList.add('editing');
+    bubble.innerHTML = '';
+
+    const meta = document.createElement('div');
+    meta.className = 'note-meta queue-meta';
+    meta.textContent = '修改排队消息';
+
+    const editor = document.createElement('textarea');
+    editor.className = 'note-edit-input';
+    editor.value = found.message.text;
+    editor.rows = 3;
+
+    const actions = document.createElement('div');
+    actions.className = 'note-actions';
+    const saveBtn = createNoteActionButton('save', '保存');
+    const cancelBtn = createNoteActionButton('cancel', '取消');
+
+    const save = () => {
+      const next = editor.value.trim();
+      const validationError = getQueuedMessageValidationError(next);
+      if (validationError) {
+        appendError(validationError);
+        editor.focus();
+        return;
+      }
+      found.message.text = next;
+      renderPendingNotes({ scroll: false });
+    };
+
+    saveBtn.addEventListener('click', save);
+    cancelBtn.addEventListener('click', () => renderPendingNotes({ scroll: false }));
+    editor.addEventListener('input', () => resizeNoteEditor(editor));
+    editor.addEventListener('keydown', (e) => {
+      if ((e.metaKey || e.ctrlKey) && e.key === 'Enter') {
+        e.preventDefault();
+        save();
+      }
+      if (e.key === 'Escape') {
+        e.preventDefault();
+        renderPendingNotes({ scroll: false });
+      }
+    });
+
+    actions.append(saveBtn, cancelBtn);
+    bubble.append(meta, editor, actions);
+    requestAnimationFrame(() => {
+      resizeNoteEditor(editor);
+      editor.focus();
+      editor.select();
+    });
+  }
+
   function sendPendingNote(noteId) {
     if (isGenerating || isBlockingSessionLoad()) {
       appendError('当前回复还在生成，稍后再发送笔记。');
@@ -535,6 +790,30 @@
     submitUserMessage(text);
   }
 
+  function scheduleQueuedMessageDrain() {
+    if (queuedMessageDrainTimer) return;
+    queuedMessageDrainTimer = setTimeout(() => {
+      queuedMessageDrainTimer = null;
+      drainQueuedMessages();
+    }, 0);
+  }
+
+  function drainQueuedMessages() {
+    if (!supportsQueuedSend() || isGenerating || currentSessionRunning || isBlockingSessionLoad()) return;
+    const queue = getCurrentQueue(false);
+    if (!queue || queue.length === 0) return;
+    const [message] = queue.splice(0, 1);
+    cleanupQueueKey(getCurrentQueueKey());
+    renderPendingNotes({ scroll: false });
+
+    const text = String(message?.text || '').trim();
+    if (!text) {
+      scheduleQueuedMessageDrain();
+      return;
+    }
+    submitUserMessage(text);
+  }
+
   function normalizeTheme(theme) {
     return THEME_OPTIONS.some((item) => item.value === theme) ? theme : 'washi';
   }
@@ -2865,6 +3144,7 @@
             localStorage.removeItem(getAgentSessionStorageKey(currentAgent));
           }
           pendingNotesByTarget.delete(session.id);
+          queuedMessagesByTarget.delete(getSessionQueueKey(session.id));
           invalidateSessionCache(session.id);
           send({ type: 'delete_session', sessionId: session.id });
           if (session.id === currentSessionId) {
@@ -2945,6 +3225,7 @@
       }
     }
     updateCwdBadge();
+    if (!running) scheduleQueuedMessageDrain();
   }
 
   function updateAgentScopedUI() {
@@ -3047,6 +3328,7 @@
     updateSessionIdBadge();
     setCurrentAgent(snapshotAgent);
     migratePendingNotesToSession(snapshot.sessionId, snapshotAgent);
+    migrateQueuedMessagesToSession(snapshot.sessionId, snapshotAgent);
     setCurrentSessionRunningState(snapshot.isRunning);
     setStatsDisplay(snapshot);
     closeUserOutlinePanel();
@@ -3285,22 +3567,69 @@
 
   // --- marked config ---
   const PREVIEW_LANGS = new Set(['html', 'svg']);
+  const MERMAID_LANGS = new Set(['mermaid', 'mmd']);
   const _previewCodeMap = new Map();
   let _previewCodeId = 0;
+  let _mermaidInitialized = false;
+  let _mermaidRenderId = 0;
+
+  function normalizeCodeLanguage(language) {
+    const lang = String(language || '').trim().split(/\s+/)[0].toLowerCase();
+    return lang || 'plaintext';
+  }
+
+  function highlightCodeBlock(code, lang) {
+    try {
+      if (hljs.getLanguage(lang)) {
+        return hljs.highlight(code, { language: lang }).value;
+      }
+      return hljs.highlightAuto(code).value;
+    } catch {
+      return escapeHtml(code);
+    }
+  }
+
+  function getCodeBlockSource(wrapper) {
+    if (!wrapper) return '';
+    const cid = wrapper.dataset.cid ? Number(wrapper.dataset.cid) : 0;
+    if (cid && _previewCodeMap.has(cid)) return _previewCodeMap.get(cid);
+    return wrapper.querySelector('code')?.textContent || '';
+  }
+
+  function createStoredCodeId(code) {
+    const cid = ++_previewCodeId;
+    _previewCodeMap.set(cid, code);
+    return cid;
+  }
+
+  function renderMermaidCodeBlock(code, lang) {
+    const cid = createStoredCodeId(code);
+    const highlighted = highlightCodeBlock(code, lang);
+    return `<div class="code-block-wrapper mermaid-code-block mermaid-diagram-mode" data-cid="${cid}">
+      <div class="code-block-header">
+        <span>${escapeHtml(lang)}</span>
+        <div class="code-block-actions">
+          <button class="code-preview-btn mermaid-toggle-btn" type="button" onclick="ccToggleMermaid(this, event)" aria-label="切换 Mermaid 图形与代码">代码</button>
+          <button class="code-preview-btn mermaid-copy-graph-btn" type="button" onclick="ccCopyMermaidDiagram(this, event)" aria-label="复制 Mermaid 图形">复制图</button>
+          <button class="code-preview-btn mermaid-download-btn" type="button" onclick="ccDownloadMermaidDiagram(this, event)" aria-label="下载 Mermaid 图形">下载图</button>
+          <button class="code-copy-btn" type="button" onclick="ccCopyCode(this, event)" aria-label="复制 Mermaid 代码">Copy</button>
+        </div>
+      </div>
+      <div class="mermaid-render-pane" data-render-state="pending">
+        <div class="mermaid-render-target" aria-label="Mermaid 图形"></div>
+        <div class="mermaid-render-error" role="alert" hidden></div>
+      </div>
+      <pre><code class="hljs language-${escapeHtml(lang)}">${highlighted}</code></pre>
+    </div>`;
+  }
 
   const renderer = new marked.Renderer();
   renderer.code = function (code, language) {
-    const lang = (language || 'plaintext').toLowerCase();
-    let highlighted;
-    try {
-      if (hljs.getLanguage(lang)) {
-        highlighted = hljs.highlight(code, { language: lang }).value;
-      } else {
-        highlighted = hljs.highlightAuto(code).value;
-      }
-    } catch {
-      highlighted = escapeHtml(code);
-    }
+    const source = String(code || '');
+    const lang = normalizeCodeLanguage(language);
+    if (MERMAID_LANGS.has(lang)) return renderMermaidCodeBlock(source, lang);
+
+    const highlighted = highlightCodeBlock(source, lang);
     const canPreview = PREVIEW_LANGS.has(lang);
     const previewBtn = canPreview
       ? `<button class="code-preview-btn" type="button" onclick="ccTogglePreview(this, event)" aria-label="预览代码块">Preview</button>`
@@ -3308,8 +3637,7 @@
     const previewPane = canPreview
       ? `<div class="code-preview-pane"><iframe class="code-preview-iframe" sandbox="allow-scripts" loading="lazy"></iframe></div>`
       : '';
-    const cid = canPreview ? (++_previewCodeId) : 0;
-    if (canPreview) _previewCodeMap.set(cid, code);
+    const cid = canPreview ? createStoredCodeId(source) : 0;
     return `<div class="code-block-wrapper${canPreview ? ' has-preview' : ''}"${canPreview ? ` data-cid="${cid}"` : ''}>
       <div class="code-block-header">
         <span>${escapeHtml(lang)}</span>
@@ -3325,8 +3653,7 @@
     event?.stopPropagation();
     const wrapper = btn?.closest?.('.code-block-wrapper');
     if (!wrapper) return;
-    const cid = wrapper.dataset.cid ? Number(wrapper.dataset.cid) : 0;
-    const code = (cid && _previewCodeMap.has(cid)) ? _previewCodeMap.get(cid) : wrapper.querySelector('code')?.textContent;
+    const code = getCodeBlockSource(wrapper);
     const defaultLabel = btn.dataset.defaultLabel || btn.textContent || 'Copy';
     btn.dataset.defaultLabel = defaultLabel;
     btn.disabled = true;
@@ -3361,6 +3688,238 @@
     }
   };
 
+  function ensureMermaidInitialized() {
+    if (!window.mermaid?.render) throw new Error('Mermaid 加载失败');
+    if (!_mermaidInitialized) {
+      window.mermaid.initialize({
+        startOnLoad: false,
+        securityLevel: 'strict',
+        theme: 'default',
+      });
+      _mermaidInitialized = true;
+    }
+    return window.mermaid;
+  }
+
+  function setMermaidRenderError(wrapper, message) {
+    const pane = wrapper?.querySelector?.('.mermaid-render-pane');
+    const errorEl = wrapper?.querySelector?.('.mermaid-render-error');
+    if (!pane || !errorEl) return;
+    pane.dataset.renderState = 'error';
+    errorEl.hidden = false;
+    errorEl.textContent = message || 'Mermaid 图形渲染失败';
+  }
+
+  async function hydrateMermaidBlock(wrapper, force = false) {
+    if (!wrapper || (!force && wrapper.dataset.mermaidRendered === '1')) return true;
+    const pane = wrapper.querySelector('.mermaid-render-pane');
+    const target = wrapper.querySelector('.mermaid-render-target');
+    const errorEl = wrapper.querySelector('.mermaid-render-error');
+    if (!pane || !target) return false;
+
+    const code = getCodeBlockSource(wrapper).trim();
+    if (!code) {
+      setMermaidRenderError(wrapper, 'Mermaid 代码为空');
+      return false;
+    }
+
+    const renderKey = String(++_mermaidRenderId);
+    wrapper.dataset.mermaidRenderKey = renderKey;
+    wrapper.dataset.mermaidRendered = '0';
+    pane.dataset.renderState = 'pending';
+    target.innerHTML = '';
+    if (errorEl) {
+      errorEl.hidden = true;
+      errorEl.textContent = '';
+    }
+
+    try {
+      const mermaidApi = ensureMermaidInitialized();
+      const result = await mermaidApi.render(`ccweb-mermaid-${renderKey}`, code);
+      if (!wrapper.isConnected || wrapper.dataset.mermaidRenderKey !== renderKey) return false;
+      target.innerHTML = typeof result === 'string' ? result : result.svg;
+      if (typeof result?.bindFunctions === 'function') result.bindFunctions(target);
+      pane.dataset.renderState = 'rendered';
+      wrapper.dataset.mermaidRendered = '1';
+      return true;
+    } catch (error) {
+      if (!wrapper.isConnected || wrapper.dataset.mermaidRenderKey !== renderKey) return false;
+      setMermaidRenderError(wrapper, error?.message || 'Mermaid 图形渲染失败');
+      return false;
+    }
+  }
+
+  function hydrateMermaidBlocks(root) {
+    if (!root) return;
+    const blocks = root.matches?.('.mermaid-code-block')
+      ? [root]
+      : Array.from(root.querySelectorAll('.mermaid-code-block'));
+    blocks.forEach((block) => {
+      hydrateMermaidBlock(block);
+    });
+  }
+
+  function hydrateRenderedMarkdown(root) {
+    hydrateMermaidBlocks(root);
+  }
+
+  function setRenderedMarkdown(target, text, hydrate = true) {
+    target.innerHTML = renderMarkdown(text);
+    if (hydrate) hydrateRenderedMarkdown(target);
+  }
+
+  window.ccToggleMermaid = function (btn, event) {
+    event?.preventDefault();
+    event?.stopPropagation();
+    const wrapper = btn?.closest?.('.mermaid-code-block');
+    if (!wrapper) return;
+    const showCode = wrapper.classList.contains('mermaid-diagram-mode');
+    wrapper.classList.toggle('mermaid-diagram-mode', !showCode);
+    wrapper.classList.toggle('mermaid-source-mode', showCode);
+    btn.textContent = showCode ? '图' : '代码';
+    if (!showCode) hydrateMermaidBlock(wrapper);
+  };
+
+  function serializeMermaidSvg(wrapper) {
+    const svg = wrapper?.querySelector?.('.mermaid-render-target svg');
+    if (!svg) return '';
+    const clone = svg.cloneNode(true);
+    if (!clone.getAttribute('xmlns')) clone.setAttribute('xmlns', 'http://www.w3.org/2000/svg');
+    if (!clone.getAttribute('width') || !clone.getAttribute('height')) {
+      const viewBox = clone.getAttribute('viewBox');
+      const parts = viewBox ? viewBox.trim().split(/\s+/).map(Number) : [];
+      if (parts.length === 4 && parts.every(Number.isFinite)) {
+        clone.setAttribute('width', String(Math.max(1, Math.ceil(parts[2]))));
+        clone.setAttribute('height', String(Math.max(1, Math.ceil(parts[3]))));
+      }
+    }
+    return new XMLSerializer().serializeToString(clone);
+  }
+
+  async function getMermaidSvgText(wrapper) {
+    if (!serializeMermaidSvg(wrapper)) {
+      await hydrateMermaidBlock(wrapper, true);
+    }
+    return serializeMermaidSvg(wrapper);
+  }
+
+  function svgTextToPngBlob(svgText) {
+    return new Promise((resolve, reject) => {
+      const svgBlob = new Blob([svgText], { type: 'image/svg+xml;charset=utf-8' });
+      const url = URL.createObjectURL(svgBlob);
+      const image = new Image();
+      image.onload = () => {
+        try {
+          const canvas = document.createElement('canvas');
+          const width = Math.max(1, image.naturalWidth || image.width || 1200);
+          const height = Math.max(1, image.naturalHeight || image.height || 800);
+          canvas.width = width;
+          canvas.height = height;
+          const ctx = canvas.getContext('2d');
+          ctx.fillStyle = '#ffffff';
+          ctx.fillRect(0, 0, width, height);
+          ctx.drawImage(image, 0, 0, width, height);
+          canvas.toBlob((blob) => {
+            URL.revokeObjectURL(url);
+            if (blob) resolve(blob);
+            else reject(new Error('PNG 导出失败'));
+          }, 'image/png');
+        } catch (error) {
+          URL.revokeObjectURL(url);
+          reject(error);
+        }
+      };
+      image.onerror = () => {
+        URL.revokeObjectURL(url);
+        reject(new Error('SVG 图形读取失败'));
+      };
+      image.src = url;
+    });
+  }
+
+  async function copyBlobToClipboard(blob, type) {
+    if (!navigator.clipboard?.write || typeof ClipboardItem === 'undefined' || !window.isSecureContext) return false;
+    await navigator.clipboard.write([new ClipboardItem({ [type]: blob })]);
+    return true;
+  }
+
+  function setTemporaryButtonLabel(btn, label, fallback, timeout = 1500) {
+    if (!btn) return;
+    const defaultLabel = btn.dataset.defaultLabel || fallback || btn.textContent || '';
+    btn.dataset.defaultLabel = defaultLabel;
+    if (btn._labelResetTimer) clearTimeout(btn._labelResetTimer);
+    btn.textContent = label;
+    btn._labelResetTimer = setTimeout(() => {
+      btn.textContent = btn.dataset.defaultLabel || defaultLabel;
+      btn._labelResetTimer = null;
+    }, timeout);
+  }
+
+  window.ccCopyMermaidDiagram = async function (btn, event) {
+    event?.preventDefault();
+    event?.stopPropagation();
+    const wrapper = btn?.closest?.('.mermaid-code-block');
+    if (!wrapper) return;
+    btn.disabled = true;
+    try {
+      const svgText = await getMermaidSvgText(wrapper);
+      if (!svgText) throw new Error('暂无可复制图形');
+      let copied = false;
+      try {
+        const pngBlob = await svgTextToPngBlob(svgText);
+        copied = await copyBlobToClipboard(pngBlob, 'image/png');
+      } catch {}
+      if (!copied) {
+        const svgBlob = new Blob([svgText], { type: 'image/svg+xml;charset=utf-8' });
+        try { copied = await copyBlobToClipboard(svgBlob, 'image/svg+xml'); } catch {}
+      }
+      if (copied) {
+        showToast('图形已复制');
+        setTemporaryButtonLabel(btn, '已复制', '复制图');
+      } else {
+        await copyTextToClipboard(svgText, '图形 SVG 已复制');
+        setTemporaryButtonLabel(btn, '已复制', '复制图');
+      }
+    } catch (error) {
+      showToast(error?.message || '复制图形失败');
+    } finally {
+      btn.disabled = false;
+    }
+  };
+
+  function downloadBlob(blob, filename) {
+    const url = URL.createObjectURL(blob);
+    const link = document.createElement('a');
+    link.href = url;
+    link.download = filename;
+    link.rel = 'noopener';
+    document.body.appendChild(link);
+    link.click();
+    link.remove();
+    setTimeout(() => URL.revokeObjectURL(url), 1000);
+  }
+
+  window.ccDownloadMermaidDiagram = async function (btn, event) {
+    event?.preventDefault();
+    event?.stopPropagation();
+    const wrapper = btn?.closest?.('.mermaid-code-block');
+    if (!wrapper) return;
+    btn.disabled = true;
+    try {
+      const svgText = await getMermaidSvgText(wrapper);
+      if (!svgText) throw new Error('暂无可下载图形');
+      const cid = wrapper.dataset.cid || Date.now();
+      const blob = new Blob([svgText], { type: 'image/svg+xml;charset=utf-8' });
+      downloadBlob(blob, `mermaid-${cid}.svg`);
+      showToast('图形已下载');
+      setTemporaryButtonLabel(btn, '已下载', '下载图');
+    } catch (error) {
+      showToast(error?.message || '下载图形失败');
+    } finally {
+      btn.disabled = false;
+    }
+  };
+
   // --- WebSocket ---
   function isBrowserOnline() {
     return !('onLine' in navigator) || navigator.onLine;
@@ -3449,6 +4008,7 @@
     switch (msg.type) {
       case 'auth_result':
         if (msg.success) {
+          const shouldLoadInitialSession = !initialSessionListHandled && !currentSessionId;
           authToken = msg.token;
           wsAuthenticated = true;
           localStorage.setItem('cc-web-token', msg.token);
@@ -3461,7 +4021,7 @@
           if (msg.mustChangePassword) {
             showForceChangePassword();
           } else {
-            pendingInitialSessionLoad = true;
+            pendingInitialSessionLoad = shouldLoadInitialSession;
           }
         } else {
           pendingSessionSwitchRequest = null;
@@ -3493,9 +4053,13 @@
         }
         if (pendingInitialSessionLoad) {
           pendingInitialSessionLoad = false;
+          initialSessionListHandled = true;
           syncViewForAgent(currentAgent, { preserveCurrent: false, loadLast: true });
         } else if (currentSessionId && !getSessionMeta(currentSessionId)) {
+          initialSessionListHandled = true;
           resetChatView(currentAgent);
+        } else {
+          initialSessionListHandled = true;
         }
         break;
 
@@ -3907,6 +4471,7 @@
     toolGroupCount = 0;
     hasGrouped = false;
     updateNoteModeUI();
+    renderPendingNotes({ scroll: false });
     // 不禁用输入框，允许用户继续输入（但无法发送）
 
     const welcome = messagesDiv.querySelector('.welcome-msg');
@@ -3980,6 +4545,7 @@
 
     if (sessionId) {
       migratePendingNotesToSession(sessionId, currentAgent);
+      migrateQueuedMessagesToSession(sessionId, currentAgent);
     }
     pendingText = '';
     activeToolCalls.clear();
@@ -3987,6 +4553,7 @@
     toolGroupCount = 0;
     hasGrouped = false;
     renderPendingNotes();
+    scheduleQueuedMessageDrain();
   }
 
   // --- Rendering ---
@@ -4010,7 +4577,7 @@
     } else if (pendingText) {
       let textDiv = bubble.querySelector('.msg-text');
       if (!textDiv) { textDiv = bubble; }
-      textDiv.innerHTML = renderMarkdown(pendingText);
+      setRenderedMarkdown(textDiv, pendingText);
     }
     syncAssistantLastSectionButton(streamEl);
     scrollToBottom();
@@ -4395,14 +4962,16 @@
             const after = content.substring(jsonMatch.index + jsonMatch[0].length);
             if (before.trim()) {
               const textDiv = document.createElement('div');
-              textDiv.innerHTML = renderMarkdown(before);
+              setRenderedMarkdown(textDiv, before, false);
               bubble.appendChild(textDiv);
+              hydrateRenderedMarkdown(textDiv);
             }
             bubble.appendChild(createTodoListElement(parsed));
             if (after.trim()) {
               const textDiv = document.createElement('div');
-              textDiv.innerHTML = renderMarkdown(after);
+              setRenderedMarkdown(textDiv, after, false);
               bubble.appendChild(textDiv);
+              hydrateRenderedMarkdown(textDiv);
             }
             return;
           }
@@ -4420,7 +4989,7 @@
           }
         } catch (e) {}
       }
-      bubble.innerHTML = renderMarkdown(content);
+      setRenderedMarkdown(bubble, content);
       return;
     }
 
@@ -4428,8 +4997,9 @@
       content.forEach(block => {
         if (block.type === 'text') {
           const textDiv = document.createElement('div');
-          textDiv.innerHTML = renderMarkdown(block.text || '');
+          setRenderedMarkdown(textDiv, block.text || '', false);
           bubble.appendChild(textDiv);
+          hydrateRenderedMarkdown(textDiv);
         } else if (block.type === 'todo_list') {
           bubble.appendChild(createTodoListElement(block));
         }
@@ -4437,7 +5007,7 @@
       return;
     }
 
-    bubble.innerHTML = renderMarkdown(String(content));
+    setRenderedMarkdown(bubble, String(content));
   }
 
   function createTodoListElement(block) {
@@ -6750,6 +7320,9 @@
     }
   });
   sendBtn.addEventListener('click', sendMessage);
+  if (queueSendBtn) {
+    queueSendBtn.addEventListener('click', queueMessageFromInput);
+  }
   if (noteModeBtn) {
     noteModeBtn.addEventListener('click', () => {
       noteMode = !noteMode;
diff --git a/public/index.html b/public/index.html
index 89166a1..0650692 100644
--- a/public/index.html
+++ b/public/index.html
@@ -14,7 +14,7 @@
       document.documentElement.dataset.dividerTime = dividerTime;
     })();
   </script>
-  <link rel="stylesheet" href="style.css?v=20260621-cross-reply-collapse-last-section-offset">
+  <link rel="stylesheet" href="style.css?v=20260622-queued-send">
   <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/styles/atom-one-dark.min.css">
 </head>
 <body>
@@ -126,6 +126,14 @@
               <path d="m15 5 3 3"></path>
             </svg>
           </button>
+          <button id="queue-send-btn" class="queue-send-btn" title="排队发送" aria-label="排队发送" type="button" hidden>
+            <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round" stroke-linejoin="round">
+              <path d="M4 6h10"></path>
+              <path d="M4 12h8"></path>
+              <path d="M4 18h10"></path>
+              <path d="m16 10 4 4-4 4"></path>
+            </svg>
+          </button>
           <button id="send-btn" class="send-btn" title="发送">
             <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round">
               <line x1="22" y1="2" x2="11" y2="13"></line><polygon points="22 2 15 22 11 13 2 9 22 2"></polygon>
@@ -154,6 +162,7 @@
 
   <script src="https://cdnjs.cloudflare.com/ajax/libs/marked/12.0.1/marked.min.js"></script>
   <script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/highlight.min.js"></script>
-  <script src="app.js?v=20260621-cross-reply-collapse-last-section-offset"></script>
+  <script src="https://cdnjs.cloudflare.com/ajax/libs/mermaid/10.9.1/mermaid.min.js"></script>
+  <script src="app.js?v=20260622-queued-send"></script>
 </body>
 </html>
diff --git a/public/style.css b/public/style.css
index 7d494d2..661ddb7 100644
--- a/public/style.css
+++ b/public/style.css
@@ -1044,6 +1044,7 @@ body.session-loading-active {
 .session-search {
   position: relative;
   margin-top: 10px;
+  width: 100%;
 }
 .session-search::before {
   content: '⌕';
@@ -1058,6 +1059,9 @@ body.session-loading-active {
   pointer-events: none;
 }
 .session-search-input {
+  -webkit-appearance: none;
+  appearance: none;
+  box-sizing: border-box;
   width: 100%;
   height: 34px;
   padding: 0 34px 0 30px;
@@ -1073,6 +1077,13 @@ body.session-loading-active {
 .session-search-input::placeholder {
   color: var(--text-muted);
 }
+.session-search-input::-webkit-search-decoration,
+.session-search-input::-webkit-search-cancel-button,
+.session-search-input::-webkit-search-results-button,
+.session-search-input::-webkit-search-results-decoration {
+  -webkit-appearance: none;
+  appearance: none;
+}
 .session-search-input:focus {
   background: var(--bg-primary);
   border-color: rgba(192, 85, 58, 0.34);
@@ -1083,6 +1094,7 @@ body.session-loading-active {
   right: 6px;
   top: 50%;
   z-index: 2;
+  transform: translateY(-50%);
   display: inline-flex;
   align-items: center;
   justify-content: center;
@@ -2454,9 +2466,24 @@ body.session-loading-active {
   border-color: var(--note-accent);
   color: var(--note-accent);
 }
+.note-action:disabled {
+  opacity: 0.42;
+  cursor: default;
+  pointer-events: none;
+}
 .note-action:active {
   transform: scale(0.96);
 }
+.note-action.queue {
+  background: var(--note-bg-strong);
+  border-color: var(--note-border);
+  color: var(--note-accent);
+}
+.note-action.queue:hover {
+  background: var(--note-accent);
+  border-color: transparent;
+  color: #fff;
+}
 .note-action.send,
 .note-action.save {
   background: var(--note-accent);
@@ -2723,6 +2750,63 @@ html[data-divider-time='hide'] .msg-bubble .agent-message-divider span {
 .code-block-wrapper.preview-mode .code-preview-pane { display: block; }
 .code-block-wrapper.preview-mode pre { display: none; }
 
+.mermaid-code-block .code-block-actions {
+  flex-wrap: wrap;
+  justify-content: flex-end;
+}
+.mermaid-code-block.mermaid-diagram-mode pre {
+  display: none;
+}
+.mermaid-code-block.mermaid-source-mode .mermaid-render-pane {
+  display: none;
+}
+.mermaid-render-pane {
+  position: relative;
+  min-height: 120px;
+  padding: 18px;
+  overflow: auto;
+  background: #fff;
+  border-top: 1px solid var(--border-color);
+  color: #1f2933;
+  -webkit-overflow-scrolling: touch;
+}
+.mermaid-render-pane[data-render-state='pending']::before {
+  content: '图形渲染中...';
+  position: absolute;
+  inset: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 18px;
+  color: #6b7280;
+  font-size: 13px;
+}
+.mermaid-render-pane[data-render-state='rendered']::before,
+.mermaid-render-pane[data-render-state='error']::before {
+  content: none;
+}
+.mermaid-render-target {
+  min-width: min-content;
+  min-height: 80px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+.mermaid-render-target svg {
+  max-width: 100%;
+  height: auto;
+}
+.mermaid-render-error {
+  padding: 12px;
+  border: 1px solid rgba(220, 53, 69, 0.28);
+  border-radius: 8px;
+  background: rgba(220, 53, 69, 0.08);
+  color: #b42318;
+  font-size: 13px;
+  line-height: 1.5;
+  white-space: pre-wrap;
+}
+
 @media (pointer: coarse) {
   .code-block-header {
     padding: 8px 10px;
@@ -3305,6 +3389,18 @@ html[data-divider-time='hide'] .msg-bubble .agent-message-divider span {
   color: var(--text-primary);
   box-shadow: 0 8px 18px rgba(45, 31, 20, 0.05);
 }
+.queued-message .queue-avatar {
+  background: var(--accent);
+}
+.queued-message .queue-bubble {
+  background:
+    linear-gradient(180deg, rgba(255, 255, 255, 0.72), transparent),
+    var(--accent-light);
+  border-color: rgba(192, 85, 58, 0.2);
+}
+.queued-message .queue-meta {
+  color: var(--accent);
+}
 .input-wrapper {
   display: flex;
   align-items: center;
@@ -3381,8 +3477,32 @@ html[data-divider-time='hide'] .msg-bubble .agent-message-divider span {
   background: var(--note-accent-hover);
   color: #fff;
 }
+.queue-send-btn {
+  appearance: none;
+  width: 36px;
+  height: 36px;
+  border: 1px solid transparent;
+  border-radius: 10px;
+  background: var(--info);
+  color: #fff;
+  cursor: pointer;
+  padding: 0;
+  flex-shrink: 0;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  transition: background 0.15s, color 0.15s, border-color 0.15s, transform 0.1s;
+}
+.queue-send-btn:hover {
+  background: var(--accent);
+  color: #fff;
+}
+.queue-send-btn:active {
+  transform: scale(0.92);
+}
 .attach-btn:disabled,
-.note-mode-btn:disabled {
+.note-mode-btn:disabled,
+.queue-send-btn:disabled {
   opacity: 0.45;
   cursor: default;
 }
@@ -3576,7 +3696,8 @@ html[data-divider-time='hide'] .msg-bubble .agent-message-divider span {
   .code-block-wrapper pre code { font-size: 12px; }
   .input-wrapper { padding: 6px 10px; border-radius: 12px; }
   .attach-btn { width: 34px; height: 34px; border-radius: 10px; }
-  .note-mode-btn { width: 34px; height: 34px; border-radius: 10px; }
+  .note-mode-btn,
+  .queue-send-btn { width: 34px; height: 34px; border-radius: 10px; }
   .send-btn, .abort-btn { width: 34px; height: 34px; }
   .pending-notes-tray { max-height: 34vh; margin-bottom: 8px; }
   .pending-note { grid-template-columns: 26px minmax(0, 1fr); gap: 7px; }
@@ -5413,6 +5534,7 @@ html[data-theme='coolvibe'] .settings-back:hover {
 }
 
 :is(html[data-theme='carbon'], html[data-theme='nocturne'], html[data-theme='cinder']) .note-mode-btn,
+:is(html[data-theme='carbon'], html[data-theme='nocturne'], html[data-theme='cinder']) .queue-send-btn,
 :is(html[data-theme='carbon'], html[data-theme='nocturne'], html[data-theme='cinder']) .send-btn.note-send {
   color: var(--bg-primary);
 }
@@ -5456,6 +5578,12 @@ html[data-theme='coolvibe'] .settings-back:hover {
   box-shadow: none;
 }
 
+:is(html[data-theme='carbon'], html[data-theme='nocturne'], html[data-theme='cinder']) .queued-message .queue-bubble {
+  background: var(--accent-light);
+  border-color: var(--border-color);
+  color: var(--text-primary);
+}
+
 :is(html[data-theme='carbon'], html[data-theme='nocturne'], html[data-theme='cinder']) .settings-inline-note code,
 :is(html[data-theme='carbon'], html[data-theme='nocturne'], html[data-theme='cinder']) .tool-call-code {
   background: rgba(0, 0, 0, 0.22);
diff --git a/server.js b/server.js
index 45386f7..2f1337a 100644
--- a/server.js
+++ b/server.js
@@ -4942,6 +4942,7 @@ const server = http.createServer((req, res) => {
 
 // === WebSocket Server ===
 const wss = new WebSocketServer({ noServer: true });
+const WS_HEARTBEAT_INTERVAL_MS = 30000;
 
 server.on('upgrade', (req, socket, head) => {
   let pathname = '';
@@ -4978,8 +4979,14 @@ wss.on('connection', (ws, req) => {
   let authToken = null;
   const wsId = crypto.randomBytes(4).toString('hex'); // short id for log correlation
   const wsConnectTime = new Date().toISOString();
+  ws.isAlive = true;
+  ws._ccWebId = wsId;
   plog('INFO', 'ws_connect', { wsId });
 
+  ws.on('pong', () => {
+    ws.isAlive = true;
+  });
+
   ws.on('message', (raw) => {
     let msg;
     try {
@@ -5120,6 +5127,26 @@ wss.on('connection', (ws, req) => {
   });
 });
 
+// WebSocket 心跳：避免反向代理因空闲连接关闭 /ws。
+const wsHeartbeatTimer = setInterval(() => {
+  for (const client of wss.clients) {
+    if (client.isAlive === false) {
+      client.terminate();
+      continue;
+    }
+    client.isAlive = false;
+    if (client.readyState === 1) {
+      try {
+        client.ping();
+      } catch (err) {
+        plog('WARN', 'ws_ping_failed', { wsId: client._ccWebId || null, error: err.message });
+        client.terminate();
+      }
+    }
+  }
+}, WS_HEARTBEAT_INTERVAL_MS);
+if (typeof wsHeartbeatTimer.unref === 'function') wsHeartbeatTimer.unref();
+
 // === Notify Config Handlers ===
 function handleSaveNotifyConfig(ws, newConfig) {
   if (!newConfig || !newConfig.provider) {