- 在 js/app.js:728-766 新增 buildDeleteButtonHtml，并在 js/app.js:1000-1034 将浮动删除按钮植入用户、AI

与错误消息气泡，同时阻断事件冒泡以免干扰 SVG 点击；带 SVG 的消息亦在 js/app.js:1042-1054 注入同样的
    删除入口。
  - 通过 js/app.js:870-924 的 confirmDeleteMessage 与 deleteMessagePermanently，删除前弹出不可恢复提示，
    确认后同步清理当前模式的对话历史、关联 SVG 缓存以及本地存储，必要时自动回退至占位视图。
  - 在 css/style.css:235-266 定义 message-with-delete 与 message-delete-btn，实现右上角高亮悬浮按钮及
    hover 反馈，保证在深浅背景下均可清晰识别。

css/style.css

@@ -2,6 +2,15 @@ body {
   font-family: 'Inter', sans-serif;
 }
 
+/* 统一处理 Iconify 图标的对齐方式，避免在按钮与文字中出现垂直偏移 */
+iconify-icon {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  vertical-align: middle;
+  line-height: 1;
+}
+
 /* 狂野线条效果 */
 .wild-border {
   border: 3px solid;
@@ -223,9 +232,55 @@ body {
   transition: color 0.2s ease;
 }
 
+/* 消息删除浮动按钮 */
+.message-with-delete {
+  position: relative;
+  padding-right: 48px;
+}
+
+.message-delete-btn {
+  position: absolute;
+  top: 8px;
+  right: 8px;
+  width: 30px;
+  height: 30px;
+  border-radius: 9999px;
+  border: 2px solid #1f2937;
+  background: rgba(255, 255, 255, 0.92);
+  color: #dc2626;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  box-shadow: 2px 2px 0 rgba(0,0,0,0.2);
+  transition: transform 0.2s ease, background 0.2s ease, color 0.2s ease;
+}
+
+.message-delete-btn:hover {
+  background: #dc2626;
+  color: #ffffff;
+  transform: scale(1.05);
+}
+
+.message-delete-btn iconify-icon {
+  font-size: 16px;
+}
+
+.svg-placeholder-block {
+  position: relative;
+}
+
+@keyframes svg-active-pulse {
+  0% { box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.35), 0 6px 12px rgba(15, 23, 42, 0.15); }
+  50% { box-shadow: 0 0 0 6px rgba(37, 99, 235, 0.15), 0 10px 18px rgba(15, 23, 42, 0.2); }
+  100% { box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.35), 0 6px 12px rgba(15, 23, 42, 0.15); }
+}
+
 .svg-placeholder-active {
-  border-color: #2563eb;
-  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.2);
+  border-color: #1d4ed8;
+  background: linear-gradient(135deg, #e0f2fe 0%, #dbeafe 100%);
+  color: #1e3a8a;
+  transform: translateY(-2px);
+  /* animation: svg-active-pulse 1.6s ease-in-out infinite; */
 }
 
 .svg-content-wrapper {

index.html

@@ -25,6 +25,7 @@
       <div class="flex items-center gap-3">
         <!-- API配置按钮 -->
         <button id="settings-btn" class="settings-btn bg-white/20 text-white p-2 border-2 border-white hover:bg-white/30 transition-all" title="API配置">
+          API配置
           <iconify-icon icon="ph:gear-six-fill" class="text-2xl"></iconify-icon>
         </button>
         
@@ -43,10 +44,10 @@
     </header>
 
     <!-- 主内容区 -->
-    <main class="flex-1 grid grid-cols-1 md:grid-cols-3 gap-4 p-4 overflow-hidden">
+    <main class="flex-1 min-h-0 grid grid-cols-1 md:grid-cols-3 gap-4 p-4 overflow-hidden">
     
       <!-- 左侧对话面板 -->
-      <div class="md:col-span-1 bg-white wild-border border-cyan-500 flex flex-col">
+      <div class="md:col-span-1 bg-white wild-border border-cyan-500 flex flex-col min-h-0">
         <!-- 对话历史顶部栏 -->
         <div class="p-3 border-b-3 border-gray-300 bg-gradient-to-r from-cyan-500 to-blue-500 flex items-center justify-between">
           <div class="flex items-center gap-2">
@@ -85,7 +86,7 @@
       </div>
     
       <!-- 右侧显示面板 -->
-      <div class="md:col-span-2 bg-white wild-border border-purple-600 flex flex-col">
+      <div class="md:col-span-2 bg-white wild-border border-purple-600 flex flex-col min-h-0">
         <div id="svg-viewer" class="flex-1 flex items-center justify-center p-4 bg-gradient-to-br from-purple-50 to-pink-50 overflow-auto">
           <div id="svg-placeholder" class="text-center text-gray-400">
             <iconify-icon icon="ph:image-square" class="text-6xl mx-auto text-purple-400"></iconify-icon>

js/app.js

@@ -26,6 +26,8 @@ class ProductCanvasApp {
     this.pendingSvgId = null;
     this.pendingCancel = false;
     this.copyClipboardSupported = typeof ClipboardItem !== 'undefined' && !!navigator.clipboard;
+    const deviceScale = typeof window !== 'undefined' ? (window.devicePixelRatio || 1) : 1;
+    this.imageExportScale = Math.min(4, Math.max(2, deviceScale));
     
     this.initElements();
     this.initEventListeners();
@@ -755,6 +757,14 @@ class ProductCanvasApp {
     `;
   }
 
+  buildDeleteButtonHtml(messageId) {
+    return `
+      <button class="message-delete-btn" title="删除此消息" onclick="event.stopPropagation(); app.confirmDeleteMessage('${messageId}')">
+        <iconify-icon icon="ph:trash-simple-bold"></iconify-icon>
+      </button>
+    `;
+  }
+
   // 组装标准化的SVG消息字符串
   buildSVGMessageContent(beforeText = '', svgBody = '', afterText = '') {
     const segments = [];
@@ -857,6 +867,62 @@ class ProductCanvasApp {
     this.renderSvgViewerForMode();
   }
 
+  confirmDeleteMessage(messageId) {
+    const history = this.conversationHistory[this.currentMode] || [];
+    const targetMessage = history.find(msg => msg.id === messageId);
+    if (!targetMessage) {
+      alert('未找到要删除的消息，请刷新后重试。');
+      return;
+    }
+
+    const typeLabel = targetMessage.type === 'user'
+      ? '这条用户消息'
+      : targetMessage.type === 'ai'
+        ? '这条AI回复'
+        : '这条提示';
+
+    const confirmed = confirm(`${typeLabel}删除后无法恢复，确定要删除吗？`);
+    if (!confirmed) {
+      return;
+    }
+
+    this.deleteMessagePermanently(messageId);
+  }
+
+  deleteMessagePermanently(messageId) {
+    const history = this.conversationHistory[this.currentMode] || [];
+    const messageIndex = history.findIndex(msg => msg.id === messageId);
+    if (messageIndex === -1) {
+      return;
+    }
+
+    history.splice(messageIndex, 1);
+
+    const svgStore = this.svgStorage[this.currentMode] || {};
+    let viewerShouldReset = false;
+    for (const [svgId, meta] of Object.entries(svgStore)) {
+      if (meta.messageId === messageId) {
+        delete svgStore[svgId];
+        if (this.currentSvgId === svgId) {
+          viewerShouldReset = true;
+        }
+      }
+    }
+
+    if (viewerShouldReset) {
+      this.currentSvgId = null;
+      this.showSvgPlaceholder();
+    }
+
+    Utils.storage.set('canvasHistory', this.conversationHistory.canvas || []);
+    Utils.storage.set('swotHistory', this.conversationHistory.swot || []);
+    Utils.storage.set('canvasSVGs', this.svgStorage.canvas || {});
+    Utils.storage.set('swotSVGs', this.svgStorage.swot || {});
+
+    this.renderConversationHistory();
+    this.renderSvgViewerForMode();
+  }
+
   // 添加用户消息
   addUserMessage(text) {
     const messageId = Utils.generateId('msg');
@@ -933,25 +999,33 @@ class ProductCanvasApp {
 
     if (message.type === 'user') {
       messageDiv.className = 'flex justify-end';
+      const deleteButton = this.buildDeleteButtonHtml(message.id);
       messageDiv.innerHTML = `
-        <div class="chat-bubble-user">
-          ${Utils.escapeHtml(message.content)}
+        <div class="chat-bubble-user message-with-delete" data-message-id="${message.id}">
+          <div>${Utils.escapeHtml(message.content)}</div>
+          ${deleteButton}
         </div>
       `;
     } else if (message.type === 'error') {
       messageDiv.className = 'flex justify-start';
+      const deleteButton = this.buildDeleteButtonHtml(message.id);
       messageDiv.innerHTML = `
-        <div class="chat-bubble-ai border-red-500">
-          <iconify-icon icon="ph:warning-circle" class="text-red-500 mr-2"></iconify-icon>
-          ${Utils.escapeHtml(message.content)}
+        <div class="chat-bubble-ai message-with-delete border-red-500" data-message-id="${message.id}">
+          ${deleteButton}
+          <div class="flex items-start gap-2">
+            <iconify-icon icon="ph:warning-circle" class="text-red-500 mt-0.5"></iconify-icon>
+            <span>${Utils.escapeHtml(message.content)}</span>
+          </div>
         </div>
       `;
     } else if (message.type === 'ai') {
       const parsedContent = typeof marked !== 'undefined' ? marked.parse(message.content) : Utils.escapeHtml(message.content);
       const actions = this.buildActionToolbar(message.id, { allowRegenerate, allowRollback });
+      const deleteButton = this.buildDeleteButtonHtml(message.id);
       messageDiv.className = 'flex justify-start';
       messageDiv.innerHTML = `
-        <div class="chat-bubble-ai relative" data-message-id="${message.id}">
+        <div class="chat-bubble-ai relative message-with-delete" data-message-id="${message.id}">
+          ${deleteButton}
           <div class="mb-1">
             ${parsedContent}
           </div>
@@ -970,11 +1044,13 @@ class ProductCanvasApp {
     const beforeHtml = parsed.beforeText ? (typeof marked !== 'undefined' ? marked.parse(parsed.beforeText) : Utils.escapeHtml(parsed.beforeText)) : '';
     const afterHtml = parsed.afterText ? (typeof marked !== 'undefined' ? marked.parse(parsed.afterText) : Utils.escapeHtml(parsed.afterText)) : '';
     const actions = this.buildActionToolbar(message.id, { allowRegenerate, allowRollback });
+    const deleteButton = this.buildDeleteButtonHtml(message.id);
 
     messageDiv.className = 'flex justify-start';
     const placeholderClass = this.currentSvgId === svgId ? 'svg-placeholder-block svg-placeholder-active' : 'svg-placeholder-block';
     messageDiv.innerHTML = `
-      <div class="chat-bubble-ai relative" data-message-id="${message.id}">
+      <div class="chat-bubble-ai relative message-with-delete" data-message-id="${message.id}">
+        ${deleteButton}
         <div>
           ${beforeHtml}
           <div class="${placeholderClass}" data-svg-id="${svgId}" onclick="app.viewSVG('${svgId}')">
@@ -1214,7 +1290,7 @@ class ProductCanvasApp {
     });
   }
 
-  async convertSvgToPngBlob(svgContent) {
+  async convertSvgToPngBlob(svgContent, options = {}) {
     const { width, height } = this.parseSvgDimensions(svgContent);
     const svgBlob = new Blob([svgContent], { type: 'image/svg+xml' });
     const url = URL.createObjectURL(svgBlob);
@@ -1222,14 +1298,16 @@ class ProductCanvasApp {
     try {
       const img = await this.loadImageFromUrl(url);
       const canvas = document.createElement('canvas');
-      const canvasWidth = Math.max(1, img.naturalWidth || width || 1024);
-      const canvasHeight = Math.max(1, img.naturalHeight || height || 768);
-      canvas.width = canvasWidth;
-      canvas.height = canvasHeight;
+      const baseWidth = Math.max(1, img.naturalWidth || width || 1024);
+      const baseHeight = Math.max(1, img.naturalHeight || height || 768);
+      const preferredScale = options.scale || this.imageExportScale || 1;
+      const exportScale = Math.min(4, Math.max(1, preferredScale));
+      canvas.width = Math.round(baseWidth * exportScale);
+      canvas.height = Math.round(baseHeight * exportScale);
 
       const ctx = canvas.getContext('2d');
-      ctx.clearRect(0, 0, canvasWidth, canvasHeight);
-      ctx.drawImage(img, 0, 0, canvasWidth, canvasHeight);
+      ctx.clearRect(0, 0, canvas.width, canvas.height);
+      ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
 
       return await new Promise((resolve, reject) => {
         canvas.toBlob((blob) => {