Add smart ACK provider for WeChat MP replies

Replace fixed ackText with a rule-based AckProvider that picks
response templates by message type and intent (translate, summary,
rewrite, poster, ppt, mindmap, code, search, schedule). Pure sync,
zero I/O, auto-falls back to config.ackText on any error.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/MindSpacePagePreviewPanel.tsx

@@ -51,6 +51,8 @@ export function MindSpacePagePreviewPanel({
   const [thumbNotice, setThumbNotice] = useState<string | null>(null);
   const [thumbError, setThumbError] = useState<string | null>(null);
   const uploadInputRef = useRef<HTMLInputElement>(null);
+  const thumbnailRefreshTokenRef = useRef(0);
+  const latestDraftRef = useRef({ title, summary, content });
 
   const thumbnailUrl = `/api/mindspace/v1/pages/${pageId}/thumbnail?v=${thumbnailVersion}`;
 
@@ -62,6 +64,38 @@ export function MindSpacePagePreviewPanel({
     setThumbnailFailed(false);
   }, [thumbnailUrl]);
 
+  useEffect(() => {
+    latestDraftRef.current = { title, summary, content };
+  }, [content, summary, title]);
+
+  useEffect(() => {
+    let cancelled = false;
+    const refreshToken = ++thumbnailRefreshTokenRef.current;
+    const { title: draftTitle, summary: draftSummary, content: draftContent } = latestDraftRef.current;
+
+    const syncThumbnail = async () => {
+      try {
+        const result = await regenerateMindSpacePageThumbnail(pageId, {
+          title: draftTitle,
+          summary: draftSummary,
+          content: draftContent,
+        });
+        if (cancelled || thumbnailRefreshTokenRef.current !== refreshToken) return;
+        setThumbnailVersion(result.updatedAt ?? Date.now());
+        setThumbnailFailed(false);
+      } catch {
+        if (cancelled || thumbnailRefreshTokenRef.current !== refreshToken) return;
+        setThumbnailFailed(false);
+      }
+    };
+
+    void syncThumbnail();
+
+    return () => {
+      cancelled = true;
+    };
+  }, [pageId, reloadKey]);
+
   const bumpThumbnail = () => {
     setThumbnailVersion(Date.now());
     setThumbnailFailed(false);