feat(沙箱): md 产物支持 AI 写作编辑与划词改写

- 新增 MarkdownAiEditor，复用 AI 写作的 TipTap 编辑器与 AI 改写流程

- 沙箱 md 增加 AI 写作视图切换，默认仍为预览；单文件隐藏文件名避免工具栏错位

- 单智能体聊天页开启 allowVirtualMarkdownEdit，生成完成后可编辑

- 会商总结页续看时自动收起研讨原料侧栏

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-web/src/components/workspace/artifacts/artifact-file-detail.tsx

@@ -11,6 +11,7 @@ import {
   LoaderIcon,
   PackageIcon,
   SaveIcon,
+  SparklesIcon,
   UploadCloudIcon,
   XIcon,
 } from "lucide-react";
@@ -37,6 +38,7 @@ import {
 } from "@/components/ui/select";
 import { ToggleGroup, ToggleGroupItem } from "@/components/ui/toggle-group";
 import { CodeEditor } from "@/components/workspace/code-editor";
+import { MarkdownAiEditor } from "@/open-canvas/components/artifact/MarkdownAiEditor";
 import { publishArtifactToKnowledge } from "@/core/agents/api";
 import { useAgent } from "@/core/agents/hooks";
 import { apiFetch } from "@/core/api";
@@ -213,6 +215,10 @@ export function ArtifactFileDetail({
     !useWriteFileStreaming &&
     !isSkillFile &&
     !isMock;
+  // 「AI 写作」md 展示开关：只要是可编辑的 markdown 就提供「AI 写作」视图（在 源码/预览 旁多一个
+  // 切换项），用户可随时切过去体验划词「AI 改写」。默认仍是「预览」，避免编辑器在内容加载期间
+  // 挂载导致白屏 + 避免复杂 md(表格/公式/HTML)误入有损编辑。
+  const canUseAiEditor = canEditArtifact;
   const [draftContent, setDraftContent] = useState("");
   const [hasLocalEdits, setHasLocalEdits] = useState(false);
   const updateArtifact = useUpdateArtifactContent();
@@ -230,7 +236,7 @@ export function ArtifactFileDetail({
     return "FILE";
   }, [filepath, isSkillFile, isSpreadsheetFile, language]);
 
-  const [viewMode, setViewMode] = useState<"code" | "preview">("code");
+  const [viewMode, setViewMode] = useState<"code" | "preview" | "edit">("code");
   const [allowAutoViewSwitch, setAllowAutoViewSwitch] = useState(true);
   const [isInstalling, setIsInstalling] = useState(false);
   const [showPreviewSwitchPulse, setShowPreviewSwitchPulse] = useState(false);
@@ -267,6 +273,7 @@ export function ArtifactFileDetail({
       return;
     }
 
+    // md/mermaid 默认预览（AI 写作视图作为可选切换项，由用户手动进入）。
     if (isSupportPreview) {
       setViewMode("preview");
       return;
@@ -598,7 +605,9 @@ export function ArtifactFileDetail({
               {fileTypeLabel}
             </span>
             <ArtifactTitle className="min-w-0">
-              {useWriteFileStreaming ? (
+              {/* markdown：隐藏文件名（仅留 MD 徽标），把横向空间让给工具栏，避免窄面板下
+                  工具栏换行错位；多文件仍保留切换下拉（靠它切文件）。文件名仍可在下载/另存为时取到。 */}
+              {language === "markdown" && !hasMultipleArtifacts ? null : useWriteFileStreaming ? (
                 <div className="truncate px-3">{getFileName(filepath)}</div>
               ) : hasMultipleArtifacts ? (
                 <Select value={filepath} onValueChange={select}>
@@ -638,10 +647,19 @@ export function ArtifactFileDetail({
                 onValueChange={(value) => {
                   if (value) {
                     setAllowAutoViewSwitch(false);
-                    setViewMode(value as "code" | "preview");
+                    setViewMode(value as "code" | "preview" | "edit");
                   }
                 }}
               >
+                {canUseAiEditor && (
+                  <ToggleGroupItem
+                    className="text-muted-foreground h-8 min-w-10 rounded-full border-0 bg-transparent px-3 shadow-none data-[state=on]:bg-background data-[state=on]:text-foreground data-[state=on]:shadow-[0_6px_14px_-10px_rgba(15,23,42,0.35)]"
+                    value="edit"
+                    aria-label="AI 写作编辑"
+                  >
+                    <SparklesIcon />
+                  </ToggleGroupItem>
+                )}
                 <ToggleGroupItem
                   className="text-muted-foreground h-8 min-w-10 rounded-full border-0 bg-transparent px-3 shadow-none data-[state=on]:bg-background data-[state=on]:text-foreground data-[state=on]:shadow-[0_6px_14px_-10px_rgba(15,23,42,0.35)]"
                   value="code"
@@ -803,6 +821,17 @@ export function ArtifactFileDetail({
             滑动到底部并继续自动下滑
           </button>
         )}
+        {viewMode === "edit" && canUseAiEditor && (
+          <MarkdownAiEditor
+            // 编辑用原始内容（与源码模式一致，不脱敏）；保存仍走头部「保存 Markdown」按钮。
+            markdown={displayContent ?? ""}
+            onChange={(value) => {
+              setDraftContent(value);
+              setHasLocalEdits(true);
+            }}
+            threadId={threadId}
+          />
+        )}
         {isSupportPreview &&
           viewMode === "preview" &&
           (language === "markdown" ||

frontend-web/src/components/workspace/chats/chat-box.tsx

@@ -423,6 +423,7 @@ const ChatBox: React.FC<{
                   className="size-full"
                   filepath={selectedArtifact}
                   threadId={threadId}
+                  allowVirtualMarkdownEdit
                 />
               </TabsContent>
               <TabsContent value="references" className="min-h-0 flex-1 overflow-y-auto p-0">
@@ -437,6 +438,7 @@ const ChatBox: React.FC<{
               className="size-full"
               filepath={selectedArtifact}
               threadId={threadId}
+              allowVirtualMarkdownEdit
             />
           ) : hasCitationReferences ? (
             <div className="relative size-full overflow-hidden">