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>

plaza-posts.mjs

@@ -38,6 +38,30 @@ function normalizeSort(value) {
   return 'recommend';
 }
 
+export function defaultPlazaCoverUrl(publicUrl) {
+  const value = String(publicUrl ?? '').trim();
+  if (!value) return '';
+  const [pathname, suffix = ''] = value.split(/([?#].*)/, 2);
+  if (!pathname) return '';
+  const nextPath = pathname.endsWith('/') ? `${pathname}index.thumbnail.png` : `${pathname}.thumbnail.png`;
+  return `${nextPath}${suffix}`;
+}
+
+export function resolvePlazaCoverUrl(inputCoverUrl, publicUrl) {
+  const value = String(inputCoverUrl ?? '').trim();
+  if (!value) return defaultPlazaCoverUrl(publicUrl);
+  if (/^https?:\/\//i.test(value)) return value;
+  const base = String(publicUrl ?? '').trim();
+  if (base && /^https?:\/\//i.test(base)) {
+    try {
+      return new URL(value, base).toString();
+    } catch {
+      return value;
+    }
+  }
+  return value;
+}
+
 function formatStats(row) {
   return {
     view_count: Number(row.view_count ?? 0),
@@ -66,11 +90,12 @@ function promoteFreshPosts(items, now = Date.now()) {
 }
 
 function formatPostRow(row, { category, viewerReacted = null, publicationUrl = null } = {}) {
+  const resolvedPublicationUrl = publicationUrl ?? row.public_url ?? null;
   return {
     id: row.id,
     title: row.title,
     summary: row.summary ?? '',
-    cover_url: row.cover_url ?? '',
+    cover_url: resolvePlazaCoverUrl(row.cover_url, resolvedPublicationUrl),
     category: category ?? {
       id: row.category_id,
       name: row.category_name ?? '',
@@ -87,7 +112,7 @@ function formatPostRow(row, { category, viewerReacted = null, publicationUrl = n
     stats: formatStats(row),
     viewer_reacted: viewerReacted,
     published_at: new Date(Number(row.published_at)).toISOString(),
-    ...(publicationUrl ? { publication_url: publicationUrl } : {}),
+    ...(resolvedPublicationUrl ? { publication_url: resolvedPublicationUrl } : {}),
     ...(row.allow_comment != null ? { allow_comment: Boolean(row.allow_comment) } : {}),
     ...(row.status ? { status: row.status } : {}),
   };
@@ -97,6 +122,8 @@ export const plazaInternals = {
   normalizeTags,
   clampLimit,
   normalizeSort,
+  defaultPlazaCoverUrl,
+  resolvePlazaCoverUrl,
 };
 
 export function createPlazaPostService(
@@ -238,7 +265,7 @@ export function createPlazaPostService(
     const categoryId = await resolveCategoryId(input?.category_id, input?.category_slug);
     const userSnapshot = await loadUserSnapshot(userId);
     const tags = normalizeTags(input?.tags);
-    const coverUrl = String(input?.cover_url ?? '').trim();
+    const coverUrl = resolvePlazaCoverUrl(input?.cover_url, publication.public_url);
     const allowComment = input?.allow_comment == null ? true : Boolean(input.allow_comment);
     const now = Date.now();
     const postId = idFactory();
@@ -298,7 +325,10 @@ export function createPlazaPostService(
 
   const updatePost = async (userId, postId, input) => {
     const [rows] = await pool.query(
-      `SELECT * FROM plaza_posts WHERE id = ? AND user_id = ? LIMIT 1`,
+      `SELECT pp.*, pr.public_url
+       FROM plaza_posts pp
+       JOIN h5_publish_records pr ON pr.id = pp.publication_id
+       WHERE pp.id = ? AND pp.user_id = ? LIMIT 1`,
       [postId, userId],
     );
     const post = rows[0];
@@ -317,7 +347,7 @@ export function createPlazaPostService(
     }
     if (input?.cover_url != null) {
       updates.push('cover_url = ?');
-      params.push(String(input.cover_url).trim());
+      params.push(resolvePlazaCoverUrl(input.cover_url, post.public_url));
     }
     if (input?.allow_comment != null) {
       updates.push('allow_comment = ?');
@@ -450,9 +480,10 @@ export function createPlazaPostService(
         : 'pp.hot_score DESC, pp.id DESC';
 
     const [rows] = await pool.query(
-      `SELECT pp.*, c.name AS category_name, c.slug AS category_slug, c.icon AS category_icon
+      `SELECT pp.*, c.name AS category_name, c.slug AS category_slug, c.icon AS category_icon, pr.public_url
        FROM plaza_posts pp
        JOIN plaza_categories c ON c.id = pp.category_id
+       JOIN h5_publish_records pr ON pr.id = pp.publication_id
        WHERE pp.status = ?
        ${categoryFilter}
        ${cursorClause}