- Add edit/delete/regenerate for user and bot messages

- Add language labels and copy buttons to code blocks
- Enhance drag-and-drop to full chat view
- Fix data consistency bugs in message operations
- Use RLock to prevent deadlock in conversation store"

channel/web/static/js/console.js

@@ -184,6 +184,8 @@ const I18N = {
         today: '今天', yesterday: '昨天', earlier: '更早',
         delete_session_confirm: '确认删除该会话？所有消息将被清除。',
         delete_session_title: '删除会话',
+        delete_message_confirm: '确认删除这条消息？',
+        delete_message_title: '删除消息',
         untitled_session: '新对话',
         context_cleared: '— 以上内容已从上下文中移除 —',
         tip_new_chat: '新建对话',
@@ -206,6 +208,10 @@ const I18N = {
         confirm_cancel: '取消',
         error_send: '发送失败，请稍后再试。', error_timeout: '请求超时，请再试一次。',
         thinking_in_progress: '思考中...', thinking_done: '已深度思考', thinking_duration: '耗时',
+        edit_message: '编辑消息',
+        regenerate_response: '重新生成',
+        edit_save: '保存并发送',
+        edit_cancel: '取消',
     },
     en: {
         console: 'Console',
@@ -380,6 +386,8 @@ const I18N = {
         today: 'Today', yesterday: 'Yesterday', earlier: 'Earlier',
         delete_session_confirm: 'Delete this session? All messages will be removed.',
         delete_session_title: 'Delete Session',
+        delete_message_confirm: 'Delete this message?',
+        delete_message_title: 'Delete Message',
         untitled_session: 'New Chat',
         context_cleared: '— Context above has been cleared —',
         tip_new_chat: 'New Chat',
@@ -402,6 +410,10 @@ const I18N = {
         confirm_cancel: 'Cancel',
         error_send: 'Failed to send. Please try again.', error_timeout: 'Request timeout. Please try again.',
         thinking_in_progress: 'Thinking...', thinking_done: 'Thought', thinking_duration: 'Duration',
+        edit_message: 'Edit message',
+        regenerate_response: 'Regenerate',
+        edit_save: 'Save and send',
+        edit_cancel: 'Cancel',
     }
 };
 
@@ -821,11 +833,45 @@ function renderMarkdown(text) {
         let html = md.render(text);
         html = _rewriteLocalImgSrc(html);
         // Order matters: video first (more specific), then image.
-        return injectImagePreviews(injectVideoPlayers(html));
+        html = injectImagePreviews(injectVideoPlayers(html));
+        // Note: Code block headers are added via DOM manipulation after insertion
+        // See addCodeBlockHeadersToElement()
+        return html;
     }
     catch (e) { return text.replace(/\n/g, '<br>'); }
 }
 
+function _addCodeBlockHeaders(container) {
+    // Add header with language label and copy button to each <pre> block using DOM manipulation
+    const preBlocks = container.querySelectorAll('pre');
+    preBlocks.forEach(pre => {
+        if (pre.parentElement && pre.parentElement.classList.contains('code-block-wrapper')) return;
+        
+        const codeEl = pre.querySelector('code');
+        if (!codeEl) return;
+        
+        const langClass = Array.from(codeEl.classList).find(c => c.startsWith('language-'));
+        const language = langClass ? langClass.replace('language-', '') : 'code';
+        const langLabel = language.charAt(0).toUpperCase() + language.slice(1);
+        
+        const wrapper = document.createElement('div');
+        wrapper.className = 'code-block-wrapper';
+        
+        const header = document.createElement('div');
+        header.className = 'code-block-header';
+        header.innerHTML = `
+            <span class="code-block-lang">${langLabel}</span>
+            <button class="code-copy-btn" title="Copy code">
+                <i class="fas fa-copy"></i>
+            </button>
+        `;
+        
+        pre.parentNode.insertBefore(wrapper, pre);
+        wrapper.appendChild(header);
+        wrapper.appendChild(pre);
+    });
+}
+
 // =====================================================================
 // Chat Module
 // =====================================================================
@@ -1085,6 +1131,22 @@ messagesDiv.addEventListener('scroll', () => {
 
 // Intercept internal navigation links in chat messages
 messagesDiv.addEventListener('click', (e) => {
+    // Code block copy button
+    const codeCopyBtn = e.target.closest('.code-copy-btn');
+    if (codeCopyBtn) {
+        e.preventDefault();
+        const wrapper = codeCopyBtn.closest('.code-block-wrapper');
+        const codeEl = wrapper && wrapper.querySelector('pre code');
+        if (codeEl) {
+            const codeText = codeEl.textContent;
+            copyToClipboard(codeText).then(() => {
+                const icon = codeCopyBtn.querySelector('i');
+                if (icon) { icon.className = 'fas fa-check'; setTimeout(() => { icon.className = 'fas fa-copy'; }, 1500); }
+            });
+        }
+        return;
+    }
+
     const copyBtn = e.target.closest('.copy-msg-btn');
     if (copyBtn) {
         e.preventDefault();
@@ -1092,13 +1154,97 @@ messagesDiv.addEventListener('click', (e) => {
         const answerEl = msgRoot && msgRoot.querySelector('.answer-content');
         const rawMd = answerEl && answerEl.dataset.rawMd;
         if (rawMd) {
-            navigator.clipboard.writeText(rawMd).then(() => {
+            copyToClipboard(rawMd).then(() => {
                 const icon = copyBtn.querySelector('i');
                 if (icon) { icon.className = 'fas fa-check'; setTimeout(() => { icon.className = 'fas fa-copy'; }, 1500); }
             });
         }
         return;
     }
+
+    // Edit user message
+    const editBtn = e.target.closest('.edit-msg-btn');
+    if (editBtn) {
+        e.preventDefault();
+        const msgRoot = editBtn.closest('.user-message-group');
+        if (msgRoot) editUserMessage(msgRoot);
+        return;
+    }
+
+    // Regenerate bot response
+    const regenerateBtn = e.target.closest('.regenerate-msg-btn');
+    if (regenerateBtn) {
+        e.preventDefault();
+        const botMsgRoot = regenerateBtn.closest('.flex.gap-3');
+        if (botMsgRoot) regenerateResponse(botMsgRoot);
+        return;
+    }
+
+    // Delete message
+    const deleteBtn = e.target.closest('.delete-msg-btn');
+    if (deleteBtn) {
+        e.preventDefault();
+        const userMsgEl = deleteBtn.closest('.user-message-group');
+        const botMsgEl = deleteBtn.closest('.flex.gap-3:not(.user-message-group)');
+        
+        if (userMsgEl) {
+            showConfirmModal(t('delete_message_title'), t('delete_message_confirm'), () => {
+                let nextSibling = userMsgEl.nextElementSibling;
+                let botReplyEl = null;
+                while (nextSibling) {
+                    if (nextSibling.classList && nextSibling.classList.contains('flex') && nextSibling.classList.contains('gap-3') && !nextSibling.classList.contains('user-message-group')) {
+                        botReplyEl = nextSibling;
+                        break;
+                    }
+                    nextSibling = nextSibling.nextElementSibling;
+                }
+                userMsgEl.remove();
+                if (botReplyEl) botReplyEl.remove();
+                
+                const userSeq = userMsgEl.dataset.seq;
+                if (userSeq) {
+                    fetch('/api/messages/delete', {
+                        method: 'POST',
+                        headers: { 'Content-Type': 'application/json' },
+                        body: JSON.stringify({ session_id: sessionId, user_seq: parseInt(userSeq) })
+                    }).then(r => r.json()).then(data => {
+                        if (data.status === 'success') console.log(`Deleted ${data.deleted} messages`);
+                    }).catch(err => console.error('Failed to delete:', err));
+                }
+            });
+        } else if (botMsgEl) {
+            showConfirmModal(t('delete_message_title'), t('delete_message_confirm'), () => {
+                // Find the preceding user message to get its seq
+                let prevUserEl = botMsgEl.previousElementSibling;
+                while (prevUserEl && !prevUserEl.classList.contains('user-message-group')) {
+                    prevUserEl = prevUserEl.previousElementSibling;
+                }
+                
+                // Delete from database (keep user message, only delete bot reply)
+                if (prevUserEl) {
+                    const userSeq = prevUserEl.dataset.seq;
+                    if (userSeq) {
+                        fetch('/api/messages/delete', {
+                            method: 'POST',
+                            headers: { 'Content-Type': 'application/json' },
+                            body: JSON.stringify({ 
+                                session_id: sessionId, 
+                                user_seq: parseInt(userSeq),
+                                delete_user: false
+                            })
+                        }).then(r => r.json()).then(data => {
+                            if (data.status === 'success') console.log(`Deleted ${data.deleted} bot reply messages`);
+                        }).catch(err => console.error('Failed to delete bot reply:', err));
+                    }
+                }
+                
+                // Remove from DOM
+                botMsgEl.remove();
+            });
+        }
+        return;
+    }
+
     const a = e.target.closest('a');
     if (!a) return;
     const href = a.getAttribute('href') || '';
@@ -1376,14 +1522,83 @@ document.addEventListener('click', (e) => {
     hideAttachMenu();
 });
 
-// Drag-and-drop support on chat input area
+// Drag-and-drop support on entire chat view
+const chatView = document.getElementById('view-chat');
 const chatInputArea = chatInput.closest('.flex-shrink-0');
-chatInputArea.addEventListener('dragover', (e) => { e.preventDefault(); e.stopPropagation(); chatInputArea.classList.add('drag-over'); });
-chatInputArea.addEventListener('dragleave', (e) => { e.preventDefault(); e.stopPropagation(); chatInputArea.classList.remove('drag-over'); });
-chatInputArea.addEventListener('drop', (e) => {
-    e.preventDefault(); e.stopPropagation();
+
+// Create drag overlay for visual feedback
+let dragOverlay = document.getElementById('drag-overlay');
+if (!dragOverlay) {
+    dragOverlay = document.createElement('div');
+    dragOverlay.id = 'drag-overlay';
+    dragOverlay.className = 'drag-overlay hidden';
+    dragOverlay.innerHTML = `
+        <div class="drag-overlay-content">
+            <i class="fas fa-cloud-arrow-up"></i>
+            <p>Drop files here to upload</p>
+        </div>
+    `;
+    chatView.appendChild(dragOverlay);
+}
+
+let dragCounter = 0;
+
+function showDragOverlay() {
+    dragOverlay.classList.remove('hidden');
+    dragOverlay.classList.add('active');
+}
+
+function hideDragOverlay() {
+    dragOverlay.classList.remove('active');
+    dragOverlay.classList.add('hidden');
+}
+
+chatView.addEventListener('dragenter', (e) => {
+    e.preventDefault();
+    e.stopPropagation();
+    dragCounter++;
+    if (e.dataTransfer.types.includes('Files')) {
+        showDragOverlay();
+    }
+});
+
+chatView.addEventListener('dragover', (e) => {
+    e.preventDefault();
+    e.stopPropagation();
+    chatInputArea.classList.add('drag-over');
+});
+
+chatView.addEventListener('dragleave', (e) => {
+    e.preventDefault();
+    e.stopPropagation();
+    dragCounter--;
+    if (dragCounter === 0) {
+        hideDragOverlay();
+        chatInputArea.classList.remove('drag-over');
+    }
+});
+
+chatView.addEventListener('drop', (e) => {
+    e.preventDefault();
+    e.stopPropagation();
+    dragCounter = 0;
+    hideDragOverlay();
     chatInputArea.classList.remove('drag-over');
-    if (e.dataTransfer.files.length) handleFileSelect(e.dataTransfer.files);
+    if (e.dataTransfer.files.length) {
+        handleFileSelect(e.dataTransfer.files);
+    }
+});
+
+document.body.addEventListener('dragover', (e) => {
+    if (e.dataTransfer.types.includes('Files')) {
+        e.preventDefault();
+    }
+});
+
+document.body.addEventListener('drop', (e) => {
+    if (e.dataTransfer.types.includes('Files')) {
+        e.preventDefault();
+    }
 });
 
 // Paste image support
@@ -1761,6 +1976,183 @@ function addUserVoiceMessage(audioUrl, caption, timestamp) {
     scrollChatToBottom(true);
 }
 
+// Clipboard helper with fallback for non-HTTPS environments
+function copyToClipboard(text) {
+    if (navigator.clipboard && window.isSecureContext) {
+        return navigator.clipboard.writeText(text);
+    }
+    // Fallback for HTTP environments
+    return new Promise((resolve, reject) => {
+        const textArea = document.createElement('textarea');
+        textArea.value = text;
+        textArea.style.position = 'fixed';
+        textArea.style.left = '-999999px';
+        textArea.style.top = '-999999px';
+        document.body.appendChild(textArea);
+        textArea.focus();
+        textArea.select();
+        try {
+            document.execCommand('copy') ? resolve() : reject(new Error('Copy failed'));
+        } catch (err) {
+            reject(err);
+        } finally {
+            textArea.remove();
+        }
+    });
+}
+
+// Edit user message: extract content, remove this and subsequent messages, fill input
+async function editUserMessage(msgEl) {
+    const rawContent = msgEl.dataset.rawContent;
+    if (!rawContent) return;
+
+    // Delete this message and ALL subsequent messages from database (cascade)
+    // Must await to ensure delete completes before user sends a new message
+    const userSeq = msgEl.dataset.seq;
+    if (userSeq) {
+        try {
+            const resp = await fetch('/api/messages/delete', {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify({ 
+                    session_id: sessionId, 
+                    user_seq: parseInt(userSeq),
+                    delete_user: true,
+                    cascade: true
+                })
+            });
+            const data = await resp.json();
+            if (data.status === 'success') console.log(`Deleted ${data.deleted} old messages`);
+        } catch (err) {
+            console.error('Failed to delete old messages:', err);
+        }
+    }
+
+    // Find all subsequent messages (this message and everything after it)
+    const messagesToRemove = [];
+    let current = msgEl;
+    while (current) {
+        if (current.classList && (current.classList.contains('user-message-group') || current.classList.contains('flex'))) {
+            messagesToRemove.push(current);
+        }
+        current = current.nextElementSibling;
+    }
+
+    // Remove all messages from this one onwards
+    messagesToRemove.forEach(el => {
+        if (el && el.parentNode) el.parentNode.removeChild(el);
+    });
+
+    // Fill input with the original content
+    chatInput.value = rawContent;
+    chatInput.style.height = 'auto';
+    chatInput.style.height = chatInput.scrollHeight + 'px';
+    chatInput.focus();
+    scrollChatToBottom();
+}
+
+// Regenerate bot response: find the preceding user message and resend it
+async function regenerateResponse(botMsgEl) {
+    let prevEl = botMsgEl.previousElementSibling;
+    while (prevEl && !prevEl.classList.contains('user-message-group')) {
+        prevEl = prevEl.previousElementSibling;
+    }
+
+    if (!prevEl) {
+        console.warn('No preceding user message found');
+        return;
+    }
+
+    const userContent = prevEl.dataset.rawContent;
+    if (!userContent) {
+        console.warn('No content in preceding user message');
+        return;
+    }
+
+    // Delete both the old user message AND bot reply from database
+    // (because /message will create a fresh user message + new bot reply)
+    // Must await to ensure delete completes before /message is sent
+    const userSeq = prevEl.dataset.seq;
+    if (userSeq) {
+        try {
+            const resp = await fetch('/api/messages/delete', {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify({ 
+                    session_id: sessionId, 
+                    user_seq: parseInt(userSeq),
+                    delete_user: true
+                })
+            });
+            const data = await resp.json();
+            if (data.status === 'success') console.log(`Deleted ${data.deleted} old messages`);
+        } catch (err) {
+            console.error('Failed to delete old messages:', err);
+        }
+    }
+
+    // Remove both the old user message and bot message from DOM
+    if (prevEl.parentNode) prevEl.parentNode.removeChild(prevEl);
+    if (botMsgEl.parentNode) botMsgEl.parentNode.removeChild(botMsgEl);
+
+    // Re-add the user message to DOM (so it appears before the loading indicator)
+    addUserMessage(userContent, new Date());
+
+    // Show loading indicator
+    const loadingEl = addLoadingIndicator();
+
+    // Resend the message
+    const timestamp = new Date();
+    const body = { session_id: sessionId, message: userContent, stream: true, timestamp: timestamp.toISOString(), lang: currentLang };
+
+    const MAX_RETRIES = 2;
+    const RETRY_DELAY_MS = 1000;
+
+    function postWithRetry(attempt) {
+        fetch('/message', {
+            method: 'POST',
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify(body)
+        })
+        .then(r => r.json())
+        .then(data => {
+            if (data.status === 'success') {
+                if (data.inline_reply) {
+                    loadingEl.remove();
+                    addBotMessage(data.inline_reply, new Date());
+                } else if (data.stream) {
+                    setSendBtnCancelMode(data.request_id);
+                    startSSE(data.request_id, loadingEl, timestamp, null);
+                } else {
+                    loadingContainers[data.request_id] = loadingEl;
+                }
+            } else {
+                loadingEl.remove();
+                addBotMessage(t('error_send'), new Date());
+                resetSendBtnSendMode();
+            }
+        })
+        .catch(err => {
+            if (err.name === 'AbortError') {
+                loadingEl.remove();
+                addBotMessage(t('error_timeout'), new Date());
+                resetSendBtnSendMode();
+                return;
+            }
+            if (attempt < MAX_RETRIES) {
+                console.warn(`[regenerateResponse] attempt ${attempt + 1} failed, retrying...`, err);
+                setTimeout(() => postWithRetry(attempt + 1), RETRY_DELAY_MS * (attempt + 1));
+                return;
+            }
+            loadingEl.remove();
+            addBotMessage(t('error_send'), new Date());
+            resetSendBtnSendMode();
+        });
+    }
+
+    postWithRetry(0);
+}
+
 function sendMessage() {
     // Do NOT branch on sendBtnMode here: Enter should always send (so
     // typing "/cancel" submits normally). Cancel is wired only to the
@@ -2252,7 +2644,7 @@ function startPolling() {
 
 function createUserMessageEl(content, timestamp, attachments) {
     const el = document.createElement('div');
-    el.className = 'flex justify-end px-4 sm:px-6 py-3';
+    el.className = 'flex justify-end px-4 sm:px-6 py-3 user-message-group';
 
     let attachHtml = '';
     if (attachments && attachments.length > 0) {
@@ -2277,9 +2669,19 @@ function createUserMessageEl(content, timestamp, attachments) {
             <div class="bg-primary-400 text-white rounded-2xl px-4 py-2.5 text-sm leading-relaxed msg-content user-bubble">
                 ${attachHtml}${textHtml}
             </div>
-            <div class="text-xs text-slate-400 dark:text-slate-500 mt-1.5 text-right">${formatTime(timestamp)}</div>
+            <div class="flex items-center justify-end gap-2 mt-1.5">
+                <button class="edit-msg-btn text-xs text-slate-300 dark:text-slate-600 hover:text-primary-400 dark:hover:text-primary-400 transition-colors cursor-pointer" title="${t('edit_message')}">
+                    <i class="fas fa-pen-to-square"></i>
+                </button>
+                <button class="delete-msg-btn text-xs text-slate-300 dark:text-slate-600 hover:text-red-500 dark:hover:text-red-400 transition-colors cursor-pointer" title="${t('delete_message_title')}">
+                    <i class="fas fa-trash"></i>
+                </button>
+                <span class="text-xs text-slate-400 dark:text-slate-500">${formatTime(timestamp)}</span>
+            </div>
         </div>
     `;
+    // Store raw content for editing
+    el.dataset.rawContent = content || '';
     return el;
 }
 
@@ -2487,6 +2889,12 @@ function createBotMessageEl(content, timestamp, requestId, msg) {
                 <button class="copy-msg-btn text-xs text-slate-300 dark:text-slate-600 hover:text-slate-500 dark:hover:text-slate-400 transition-colors cursor-pointer" title="${currentLang === 'zh' ? '复制' : 'Copy'}">
                     <i class="fas fa-copy"></i>
                 </button>
+                <button class="regenerate-msg-btn text-xs text-slate-300 dark:text-slate-600 hover:text-primary-400 dark:hover:text-primary-400 transition-colors cursor-pointer" title="${t('regenerate_response')}">
+                    <i class="fas fa-rotate-right"></i>
+                </button>
+                <button class="delete-msg-btn text-xs text-slate-300 dark:text-slate-600 hover:text-red-500 dark:hover:text-red-400 transition-colors cursor-pointer" title="${t('delete_message_title')}">
+                    <i class="fas fa-trash"></i>
+                </button>
                 <button class="speak-msg-btn text-xs text-slate-300 dark:text-slate-600 hover:text-slate-500 dark:hover:text-slate-400 transition-colors cursor-pointer" title="${t('speak_msg')}" style="display:none;">
                     <i class="fas fa-volume-up"></i>
                 </button>
@@ -2709,6 +3117,10 @@ function loadHistory(page) {
                 const el = msg.role === 'user'
                     ? createUserMessageEl(msg.content, ts)
                     : createBotMessageEl(msg.content || '', ts, null, msg);
+                // Store seq for delete functionality
+                if (msg._seq !== undefined) {
+                    el.dataset.seq = msg._seq;
+                }
                 fragment.appendChild(el);
             });
 
@@ -3285,6 +3697,8 @@ function applyHighlighting(container) {
                 hljsLib.highlightElement(block);
             }
         });
+        // Add language labels and copy buttons to code blocks
+        _addCodeBlockHeaders(root);
     }, 0);
 }