fix: 空评论列表 500，并完善撤回审计与角色说明

空切片 JSON 统一为数组；撤回保留正文供站长阅读，成员侧居中提示与重新编辑；头像支持拖放；角色弹窗补全职责说明并汇入封禁。

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

frontend/app/chat/ChatShell.tsx

@@ -22,6 +22,7 @@ import {
 } from "@/lib/api";
 import { realtime, RT_CHAT_UNREAD, RT_CHAT_MEMBERSHIP } from "@/lib/realtime";
 import type { RtChatUnreadData, RtChatMembershipData } from "@/lib/realtime";
+import { onDocumentVisible } from "@/lib/visibilityReconcile";
 import { toast } from "@/lib/toast";
 import Avatar from "@/components/Avatar";
 import ContextMenu, { type CtxMenuItem } from "@/components/ContextMenu";
@@ -114,28 +115,35 @@ export default function ChatShell({
     setRooms(sortRooms(initialRooms));
   }, [initialRooms]);
 
-  const refreshRooms = useCallback(async () => {
+  const roomsInFlight = useRef(false);
+  const lastRoomsFetchAt = useRef(0);
+
+  const refreshRooms = useCallback(async (opts?: { force?: boolean }) => {
+    const now = Date.now();
+    if (!opts?.force) {
+      if (roomsInFlight.current) return;
+      // 切房/回前台可合并；建群、被邀请等走 force
+      if (now - lastRoomsFetchAt.current < 2_000) return;
+    }
+    roomsInFlight.current = true;
+    lastRoomsFetchAt.current = now;
     try {
       const res = await apiListChatRooms(1, 50, "", "joined");
       setRooms(sortRooms(res.rooms || []));
     } catch {
       // 静默
+    } finally {
+      roomsInFlight.current = false;
     }
   }, []);
 
-  // 每次进入消息壳都用 HTTP 拉最新排序（避免首页 Link 预取/路由缓存导致新消息会话不置顶）
+  // 进入消息壳 / 切会话：HTTP 拉最新排序（避开预取缓存）
   useEffect(() => {
-    refreshRooms();
+    void refreshRooms();
   }, [refreshRooms, activeRoomId]);
 
-  // 从其他标签页切回时也对账一次
-  useEffect(() => {
-    const onVisible = () => {
-      if (document.visibilityState === "visible") refreshRooms();
-    };
-    document.addEventListener("visibilitychange", onVisible);
-    return () => document.removeEventListener("visibilitychange", onVisible);
-  }, [refreshRooms]);
+  // 从其他标签页切回时对账（10s 限频 + 上方 2s 合并）
+  useEffect(() => onDocumentVisible(() => void refreshRooms()), [refreshRooms]);
 
   // 实时未读：更新侧栏角标与预览，按置顶规则重排（不盲目置顶到最前）
   useEffect(() => {
@@ -145,7 +153,7 @@ export default function ChatShell({
       setRooms((prev) => {
         const idx = prev.findIndex((r) => r.id === data.room_id);
         if (idx < 0) {
-          refreshRooms();
+          void refreshRooms({ force: true });
           return prev;
         }
         const next = [...prev];
@@ -179,7 +187,7 @@ export default function ChatShell({
     const off = realtime.on<RtChatMembershipData>(RT_CHAT_MEMBERSHIP, (data) => {
       if (!data) return;
       if (data.status === "invited" || data.status === "dissolved" || data.status === "kicked") {
-        refreshRooms();
+        void refreshRooms({ force: true });
       }
     });
     return off;
@@ -230,7 +238,7 @@ export default function ChatShell({
       setQuery("");
       setUserHits([]);
       router.push(`/chat/${room.id}`);
-      refreshRooms();
+      void refreshRooms({ force: true });
     } catch (e) {
       toast(e instanceof Error ? e.message : "无法发起私聊");
     }
@@ -524,7 +532,7 @@ export default function ChatShell({
             setShowCreate(false);
             toast("群已创建", "ok");
             router.push(`/chat/${id}`);
-            refreshRooms();
+            void refreshRooms({ force: true });
           }}
         />
       )}