diff --git a/web/src/features/groups/GroupAdminModal.tsx b/web/src/features/groups/GroupAdminModal.tsx
index 950f368c..53aab35a 100644
--- a/web/src/features/groups/GroupAdminModal.tsx
+++ b/web/src/features/groups/GroupAdminModal.tsx
@@ -410,6 +410,13 @@ function MutesSubView({ topicId, muted, onClose }: { topicId: string; muted: Gro
   const queryClient = useQueryClient();
   const [adding, setAdding] = useState(false);
   const [error, setError] = useState('');
+  // `GroupMute` itself carries only a bare `user_id` (see its own type comment) -- resolve a real
+  // name/avatar the same way ConversationView.tsx's `memberByUserId` does, rather than rendering the
+  // raw id (this list previously crashed outright reading a `.user.display_name` that never existed
+  // on the real response, confirmed live: `Cannot read properties of undefined (reading 'user_id')`
+  // the moment a real muted member was ever rendered here).
+  const membersQuery = useQuery({ queryKey: ['group-members', topicId], queryFn: () => getAllGroupMembers(topicId) });
+  const memberByUserId = new Map((membersQuery.data || []).map((m) => [m.user_id, m]));
   const invalidate = () => queryClient.invalidateQueries({ queryKey: ['group-mutes', topicId] });
   const muteMutation = useMutation({
     mutationFn: (userId: string) => muteGroupMembers(topicId, [{ user_id: userId, expires_at: null }]),
@@ -439,22 +446,25 @@ function MutesSubView({ topicId, muted, onClose }: { topicId: string; muted: Gro
         />
       ) : (
         <>
-          {muted.map((m) => (
-            <div key={m.user.user_id} className="flex items-center gap-3 px-3 py-2">
-              <span className={`grid h-9 w-9 flex-none place-items-center rounded-lg text-sm font-medium text-white ${avatarBgClass(m.user.user_id)}`}>
-                {avatarLetter(m.user.display_name)}
-              </span>
-              <span className="flex-1 truncate text-sm text-text-body">{m.user.display_name || m.user.user_id}</span>
-              <button
-                type="button"
-                onClick={() => unmuteMutation.mutate(m.user.user_id)}
-                disabled={unmuteMutation.isPending}
-                className="text-xs text-accent disabled:opacity-50"
-              >
-                解除禁言
-              </button>
-            </div>
-          ))}
+          {muted.map((m) => {
+            const name = memberByUserId.get(m.user_id)?.display_name || m.user_id;
+            return (
+              <div key={m.user_id} className="flex items-center gap-3 px-3 py-2">
+                <span className={`grid h-9 w-9 flex-none place-items-center rounded-lg text-sm font-medium text-white ${avatarBgClass(m.user_id)}`}>
+                  {avatarLetter(name)}
+                </span>
+                <span className="flex-1 truncate text-sm text-text-body">{name}</span>
+                <button
+                  type="button"
+                  onClick={() => unmuteMutation.mutate(m.user_id)}
+                  disabled={unmuteMutation.isPending}
+                  className="text-xs text-accent disabled:opacity-50"
+                >
+                  解除禁言
+                </button>
+              </div>
+            );
+          })}
           <button type="button" onClick={() => setAdding(true)} className="flex w-full items-center gap-2 px-3 py-2 text-sm text-accent">
             <Icon name="add" className="text-[18px]" />
             禁言成员
diff --git a/web/src/features/messages/ConversationView.tsx b/web/src/features/messages/ConversationView.tsx
index f9348a28..f182d932 100644
--- a/web/src/features/messages/ConversationView.tsx
+++ b/web/src/features/messages/ConversationView.tsx
@@ -17,7 +17,7 @@ import { GroupAnnouncementModal } from '@/features/groups/GroupAnnouncementModal
 import { JoinRequestsModal } from '@/features/groups/JoinRequestsModal';
 import { useBootstrap } from '@/lib/api/hooks';
 import { favoriteMessages, type MediaType, recallMessage } from '@/lib/api/messages';
-import { getAllGroupMembers, getGroup, getGroupGovernance, getGroupMutes, getGroupSummary } from '@/lib/api/groups';
+import { getAllGroupMembers, getAllGroupMutes, getGroup, getGroupGovernance, getGroupSummary } from '@/lib/api/groups';
 import { getMe } from '@/lib/api/profile';
 import { avatarBgClass, avatarLetter } from '@/lib/avatar';
 import { FETCH_PAGE_TRIGGER, MESSAGES_PAGE } from '@/lib/config';
@@ -301,9 +301,20 @@ export function ConversationView() {
     queryFn: () => getGroupGovernance(topicId || ''),
     enabled: isGroup,
   });
+  // Real, live-confirmed crash (not theoretical): this used to call `getGroupMutes` (single page,
+  // `{items, next_cursor}` shape) under query key `['group-mutes', topicId]` -- the EXACT SAME key
+  // `GroupAdminModal.tsx` uses for `getAllGroupMutes` (all pages, flat array). Both mounted together
+  // (opening 群管理 from a group's own conversation screen, which is the only way to reach it) means
+  // whichever query resolves last overwrites the shared cache entry with ITS shape; the other
+  // consumer then reads `array.items.length` -- `.items` is undefined on a plain array, and unlike
+  // `mutesQuery.data?.items.length`'s leading `?.`, nothing guards THAT specific property access, so
+  // it throws and takes down the whole conversation screen. Matching `getAllGroupMutes` here (same
+  // function, same shape, same key) turns this from two competing queries into one correctly-shared
+  // one -- also fixes this subline's own under-count for any group with more muted members than a
+  // single page holds, the same truncation bug `getAllGroupMutes`'s own doc comment already flags.
   const mutesQuery = useQuery({
     queryKey: ['group-mutes', topicId],
-    queryFn: () => getGroupMutes(topicId || ''),
+    queryFn: () => getAllGroupMutes(topicId || ''),
     enabled: isGroup,
   });
   const memberByUserId = useMemo(() => new Map((membersQuery.data || []).map((m) => [m.user_id, m])), [membersQuery.data]);
@@ -311,7 +322,7 @@ export function ConversationView() {
   const isGroupAdmin = myMember?.role === 'owner' || myMember?.role === 'admin';
   const groupSublineParts = [
     governanceQuery.data?.join_approval ? '已开启进群验证' : null,
-    mutesQuery.data?.items.length ? `${mutesQuery.data.items.length} 位成员被禁言` : null,
+    mutesQuery.data?.length ? `${mutesQuery.data.length} 位成员被禁言` : null,
   ].filter(Boolean);
 
   if (!topicId) return null;
diff --git a/web/src/lib/api/groups.ts b/web/src/lib/api/groups.ts
index b260dec9..fe5f539f 100644
--- a/web/src/lib/api/groups.ts
+++ b/web/src/lib/api/groups.ts
@@ -239,11 +239,18 @@ export function removeGroupAdmin(topic: string, userId: string, version: number)
   );
 }
 
+/** Real response is flat (confirmed live: `{muted_at,muted_by,reason,status,user_id,version}`) --
+ *  no nested `user` object, and no `display_name` at all (unlike e.g. group members, this endpoint
+ *  never returns a readable name, only the bare id -- callers needing one must cross-reference the
+ *  member list themselves, same as GroupFilesModal already has to for `uploader_id`). */
 export interface GroupMute {
-  user: { user_id: string; display_name?: string };
+  user_id: string;
   muted_by?: string;
   muted_at: string;
-  expires_at: string | null;
+  expires_at?: string | null;
+  reason?: string;
+  status?: string;
+  version?: number;
 }
 
 export function muteGroupMembers(topic: string, members: Array<{ user_id: string; expires_at: string | null }>, reason?: string) {