diff --git a/app.py b/app.py
index 3061c04..662f0a7 100644
--- a/app.py
+++ b/app.py
@@ -700,12 +700,43 @@ def api_add_friend():
     friend_id = data.get('friend_id')
     if not friend_id or friend_id == user_id:
         return jsonify({'success': False, 'message': '无效的好友ID'}), 400
+
+    # 检查是否已经是好友或有待处理的请求
     existing = Friend.query.filter(
         ((Friend.user_id == user_id) & (Friend.friend_id == friend_id)) |
         ((Friend.user_id == friend_id) & (Friend.friend_id == user_id))
     ).first()
+
     if existing:
-        return jsonify({'success': False, 'message': '已经是好友或已发送请求'}), 400
+        # 如果已经是好友，不允许重复申请
+        if existing.status == 'accepted':
+            return jsonify({'success': False, 'message': '已经是好友'}), 400
+
+        # 如果有待处理的请求，不允许重复发送
+        if existing.status == 'pending':
+            return jsonify({'success': False, 'message': '已发送好友请求，请等待对方处理'}), 400
+
+        # 如果之前被拒绝，允许重新发送（更新状态为pending）
+        if existing.status == 'rejected':
+            # 确保是当前用户发起的请求才能更新
+            if existing.user_id == user_id:
+                existing.status = 'pending'
+                existing.created_at = datetime.utcnow()
+                db.session.flush()
+
+                # 重新发送通知给对方
+                sender_name = session['user'].get('name', '未知用户')
+                notif = Notification(user_id=friend_id, type='friend_request',
+                                   content=f'{sender_name} 请求添加你为好友',
+                                   from_user=sender_name, post_id=existing.id)
+                db.session.add(notif)
+                db.session.commit()
+                return jsonify({'success': True, 'message': '好友请求已重新发送'})
+            else:
+                # 如果是对方之前发起的请求被拒绝，当前用户可以创建新的请求
+                pass
+
+    # 创建新的好友请求
     friend_req = Friend(user_id=user_id, friend_id=friend_id, status='pending')
     db.session.add(friend_req)
     db.session.flush()
@@ -3052,7 +3083,8 @@ def api_unregister_contest(contest_id):
 def api_contest_posts(contest_id):
     """获取杯赛讨论区帖子列表"""
     contest = Contest.query.get_or_404(contest_id)
-    posts = Post.query.filter_by(contest_id=contest_id).order_by(Post.created_at.desc()).all()
+    # 置顶帖子在前，然后按创建时间倒序
+    posts = Post.query.filter_by(contest_id=contest_id).order_by(Post.pinned.desc(), Post.created_at.desc()).all()
     user = get_current_user()
     uid = user['id'] if user else None
     data = []
@@ -3127,11 +3159,11 @@ def api_search_posts():
         query = query.filter_by(tag=tag)
 
     if sort == 'hottest':
-        query = query.order_by(Post.likes.desc())
+        query = query.order_by(Post.pinned.desc(), Post.likes.desc())
     elif sort == 'most_replies':
-        query = query.order_by(Post.replies_count.desc())
+        query = query.order_by(Post.pinned.desc(), Post.replies_count.desc())
     else:
-        query = query.order_by(Post.created_at.desc())
+        query = query.order_by(Post.pinned.desc(), Post.created_at.desc())
 
     posts = query.all()
     user = session.get('user')
@@ -3712,6 +3744,25 @@ def api_create_post_with_poll():
 def api_share_post(post_id):
     return jsonify({'success': True})
 
+@app.route('/api/posts/<int:post_id>/pin', methods=['POST'])
+@login_required
+def api_pin_post(post_id):
+    """置顶/取消置顶帖子（仅管理员）"""
+    user = session.get('user')
+    if user.get('role') != 'admin':
+        return jsonify({'success': False, 'message': '只有管理员可以置顶帖子'}), 403
+
+    post = Post.query.get(post_id)
+    if not post:
+        return jsonify({'success': False, 'message': '帖子不存在'}), 404
+
+    # 切换置顶状态
+    post.pinned = not post.pinned
+    db.session.commit()
+
+    action = '置顶' if post.pinned else '取消置顶'
+    return jsonify({'success': True, 'message': f'帖子已{action}', 'pinned': post.pinned})
+
 # ========== 聊天系统页面 ==========
 @app.route('/chat')
 @login_required
diff --git a/templates/forum.html b/templates/forum.html
index 36fc51a..fd3a068 100644
--- a/templates/forum.html
+++ b/templates/forum.html
@@ -563,7 +563,7 @@ async function openPost(pid) {
     const p = data.data;
     const replies = data.replies || [];
     const isAuthor = CU && CU.id === p.author_id;
-    const isTeacher = CU && CU.role === 'teacher';
+    const isTeacher = CU && (CU.role === 'teacher' || CU.role === 'admin');
     const reactions = p.reactions || {};
 
     let reactBtns = '';