feat: 评论/帖子编辑历史与编辑标记，内容锁定

- 新增 smartDiff 差异计算与 EditHistoryModal 编辑历史弹窗，替换原 CommentEditHistoryModal
- 新增 PostEditedMark 编辑标记展示
- 新增内容锁定机制（content_lock）防止并发编辑冲突
- 审核与通知服务适配

frontend/components/CommentSection.tsx

@@ -1,4 +1,4 @@
-"use client";
+"use client";
 
 import { useEffect, useRef, useState } from "react";
 import { useRouter } from "next/navigation";
@@ -7,6 +7,7 @@ import {
   MessagesSquare,
   ChevronRight,
   ChevronDown,
+  Lock,
 } from "lucide-react";
 import {
   apiCreateComment,
@@ -16,13 +17,14 @@ import {
   apiUpdateComment,
   apiAcceptBounty,
   apiAcceptQuestion,
+  apiCommentHistory,
   apiAdminApproveComment,
   apiAdminRejectComment,
   postDeleteTypeLabel,
   type CommentNode,
   type User,
 } from "@/lib/api";
-import { canModerateBoard, canStaffSoftDelete, canPurgeContent } from "@/lib/roles";
+import { canModerateBoard, canStaffSoftDelete, canPurgeContent, isStaff } from "@/lib/roles";
 import { toast } from "@/lib/toast";
 import { formatCommentTime, formatDateTime } from "@/lib/format";
 import { useAllowComments, useCommentsRequireLogin } from "@/components/CommentsPolicyProvider";
@@ -36,7 +38,7 @@ import MarkdownBodyClient from "@/components/MarkdownBodyClient";
 import MarkdownEditor from "@/components/MarkdownEditor";
 import ConfirmDialog from "@/components/ConfirmDialog";
 import DeleteCommentModal, { type DeleteCommentPayload } from "@/components/DeleteCommentModal";
-import CommentEditHistoryModal from "@/components/CommentEditHistoryModal";
+import EditHistoryModal from "@/components/EditHistoryModal";
 
 interface CommentSectionProps {
   postId: string;
@@ -56,6 +58,12 @@ interface CommentSectionProps {
   acceptedCommentId?: number;
   /** 抽奖已开奖：中奖楼层评论 ID（每名中奖者仅其最早主评一条） */
   winnerCommentIds?: number[];
+  /** 帖子是否被管理员手动锁定（普通用户不可回复/编辑评论，staff 豁免） */
+  postLocked: boolean;
+  /** 评论可编辑时长（小时）；0=不锁定；staff 豁免 */
+  commentEditLockHours: number;
+  /** 旧帖回复确认提示（后端按查看者计算；存在时提交回复前需用户确认，确认后发送并扣分） */
+  necroReply?: { after_hours: number; penalty: number } | null;
 }
 
 // 递归统计子树回复数（彻底删除级联提示用）
@@ -63,6 +71,9 @@ function countReplies(node: CommentNode): number {
   return node.replies?.reduce((acc, r) => acc + 1 + countReplies(r), 0) ?? 0;
 }
 
+/** 评论正文字符上限（与后端 handler/comment.go 校验一致） */
+const COMMENT_MAX = 5000;
+
 function findComment(nodes: CommentNode[], id: number): CommentNode | null {
   for (const n of nodes) {
     if (n.id === id) return n;
@@ -196,11 +207,22 @@ export default function CommentSection({
   acceptMode = null,
   acceptedCommentId = 0,
   winnerCommentIds = [],
+  postLocked,
+  commentEditLockHours,
+  necroReply = null,
 }: CommentSectionProps) {
   const winnerCommentIdSet = new Set(winnerCommentIds.filter((id) => id > 0));
   const router = useRouter();
   const commentsOpen = useAllowComments();
   const commentsRequireLogin = useCommentsRequireLogin();
+  const staffViewer = !!user && isStaff(user.role);
+  /** 锁帖后普通用户禁止回复与编辑自己的评论，staff 豁免 */
+  const replyBlocked = postLocked && !staffViewer;
+  /** 评论是否已超过可编辑时限（staff 豁免；0=不启用） */
+  const commentTimeLocked = (createdAt: string) =>
+    !staffViewer &&
+    commentEditLockHours > 0 &&
+    Date.now() - new Date(createdAt).getTime() > commentEditLockHours * 3_600_000;
   const [content, setContent] = useState("");
   // 内联回复目标：同一时间只有一个回复框；草稿按目标评论隔离
   const [replyTarget, setReplyTarget] = useState<{
@@ -221,6 +243,8 @@ export default function CommentSection({
   const [replyUploading, setReplyUploading] = useState(false);
   const [editUploading, setEditUploading] = useState(false);
   const [awayHref, setAwayHref] = useState<string | null>(null);
+  // 旧帖回复确认：记录待确认的提交入口（主楼层 / 内联回复）
+  const [necroConfirm, setNecroConfirm] = useState<null | "floor" | "reply">(null);
   const [discardReplyOpen, setDiscardReplyOpen] = useState(false);
   const [discardEditOpen, setDiscardEditOpen] = useState(false);
   const [deleting, setDeleting] = useState(false);
@@ -237,6 +261,7 @@ export default function CommentSection({
   const [editContent, setEditContent] = useState("");
   const [savingEdit, setSavingEdit] = useState(false);
   const [historyCommentId, setHistoryCommentId] = useState<number | null>(null);
+  const [historyCommentContent, setHistoryCommentContent] = useState("");
   // 折叠状态：哪些楼层展开了子回复（默认全部折叠，SSR 初始为收起）
   const [expandedFloors, setExpandedFloors] = useState<Set<number>>(new Set());
 
@@ -304,6 +329,11 @@ export default function CommentSection({
 
   const handleSubmit = (e: React.FormEvent) => {
     e.preventDefault();
+    // 旧帖回复：确认后才发送并扣分（后端按查看者下发提示，staff/待审用户不会拿到）
+    if (necroReply) {
+      setNecroConfirm("floor");
+      return;
+    }
     void submitFloor();
   };
 
@@ -347,6 +377,11 @@ export default function CommentSection({
 
   const handleSubmitReply = (e: React.FormEvent) => {
     e.preventDefault();
+    // 旧帖回复：确认后才发送并扣分
+    if (necroReply) {
+      setNecroConfirm("reply");
+      return;
+    }
     void submitReply();
   };
 
@@ -472,9 +507,16 @@ export default function CommentSection({
     (user.id === comment.user?.id ||
       canStaffSoftDelete(user, boardId, comment.user?.role));
 
-  const canEdit = (comment: CommentNode) => canSoftDelete(comment);
+  const canEdit = (comment: CommentNode) => {
+    if (!canSoftDelete(comment)) return false;
+    // 作者本人编辑：锁帖与可编辑时限限制（staff 豁免；版主编辑他人不受此限）
+    if (user?.id === comment.user?.id && (replyBlocked || commentTimeLocked(comment.created_at))) {
+      return false;
+    }
+    return true;
+  };
 
-  const canViewHistory = !!user && canModerateBoard(user, boardId);
+  const canViewHistory = !!user;
 
   const canPurge = (comment: CommentNode) =>
     !!user && canPurgeContent(user.role) && canModerateBoard(user, boardId);
@@ -615,9 +657,10 @@ export default function CommentSection({
             density="comment"
             value={editContent}
             onChange={(v) => {
-              setEditContent(v);
+              setEditContent(v.slice(0, COMMENT_MAX));
               if (editError) setEditError("");
             }}
+            maxChars={COMMENT_MAX}
             disabled={savingEdit}
             autoFocus
             allowHide={false}
@@ -671,7 +714,14 @@ export default function CommentSection({
     if (!c.edited) return null;
     if (canViewHistory) {
       return (
-        <button type="button" className="cmt-edited" onClick={() => setHistoryCommentId(c.id)}>
+        <button
+          type="button"
+          className="cmt-edited"
+          onClick={() => {
+            setHistoryCommentContent(c.content);
+            setHistoryCommentId(c.id);
+          }}
+        >
           已编辑
         </button>
       );
@@ -693,11 +743,15 @@ export default function CommentSection({
         onSelect: () => startEdit(c),
       });
     }
-    if (canViewHistory) {
+    // 未编辑（无修订快照）的评论不展示历史入口，避免打开空记录
+    if (canViewHistory && c.edited) {
       items.push({
         key: "history",
         label: "编辑历史",
-        onSelect: () => setHistoryCommentId(c.id),
+        onSelect: () => {
+          setHistoryCommentContent(c.content);
+          setHistoryCommentId(c.id);
+        },
       });
     }
     if (canRestore(c)) {
@@ -758,9 +812,10 @@ export default function CommentSection({
           density="comment"
           value={replyContent}
           onChange={(v) => {
-            setReplyContent(v);
+            setReplyContent(v.slice(0, COMMENT_MAX));
             if (replyError) setReplyError("");
           }}
+          maxChars={COMMENT_MAX}
           disabled={submitting}
           autoFocus
           allowHide={false}
@@ -1015,7 +1070,7 @@ export default function CommentSection({
               </div>
               {renderContentOrEditor(c)}
               <div className="cmt-actions">
-                {commentsOpen && user && editingId !== c.id && (
+                {commentsOpen && user && !replyBlocked && editingId !== c.id && (
                   <button
                     type="button"
                     onClick={() => openReply(c, floor)}
@@ -1117,7 +1172,7 @@ export default function CommentSection({
             </div>
             {renderContentOrEditor(c)}
             <div className="cmt-actions">
-              {commentsOpen && user && editingId !== c.id && (
+              {commentsOpen && user && !replyBlocked && editingId !== c.id && (
                 <button
                   type="button"
                   onClick={() => openReply(c, floor)}
@@ -1214,7 +1269,18 @@ export default function CommentSection({
         ) : null}
       </div>
 
-      {user ? (
+      {replyBlocked ? (
+        <div
+          className="mb-8 px-5 py-4 rounded-2xl flex items-center gap-2.5 border"
+          style={{ borderColor: "var(--line)", background: "transparent" }}
+          role="status"
+        >
+          <Lock size={15} style={{ color: "var(--ink-3)" }} className="shrink-0" />
+          <span className="text-sm" style={{ color: "var(--ink-2)" }}>
+            帖子已被锁定，暂时无法回复
+          </span>
+        </div>
+      ) : user ? (
         <form onSubmit={handleSubmit} className="mb-6">
           <div className="cmt-md-editor cmt-md-editor-floor scroll-mt-28">
             <MarkdownEditor
@@ -1222,9 +1288,10 @@ export default function CommentSection({
               density="comment"
               value={content}
               onChange={(v) => {
-                setContent(v);
+                setContent(v.slice(0, COMMENT_MAX));
                 if (floorError) setFloorError("");
               }}
+              maxChars={COMMENT_MAX}
               disabled={submitting}
               allowHide={false}
               ariaLabel="发表评论"
@@ -1355,9 +1422,29 @@ export default function CommentSection({
         onCancel={() => setDiscardEditOpen(false)}
       />
 
-      <CommentEditHistoryModal
+      {/* 旧帖回复确认：确认后才发送并扣分（提示由后端按查看者下发） */}
+      <ConfirmDialog
+        open={necroConfirm !== null}
+        title="回复旧帖提醒"
+        message={`该帖已超过 ${necroReply?.after_hours ?? 0} 小时没有新回复，回复将扣除 ${necroReply?.penalty ?? 0} 积分。确定继续吗？`}
+        confirmLabel="继续回复"
+        onConfirm={() => {
+          const kind = necroConfirm;
+          setNecroConfirm(null);
+          if (kind === "floor") void submitFloor();
+          else if (kind === "reply") void submitReply();
+        }}
+        onCancel={() => setNecroConfirm(null)}
+      />
+
+      <EditHistoryModal
         open={historyCommentId != null}
-        commentId={historyCommentId}
+        title="评论编辑历史"
+        currentContent={historyCommentContent}
+        fetchPage={(p, s) => {
+          if (historyCommentId == null) return Promise.reject(new Error("未选择评论"));
+          return apiCommentHistory(historyCommentId, p, s);
+        }}
         onClose={() => setHistoryCommentId(null)}
       />
     </section>