支持评论级联软删与后台回收站，并完善 Markdown 代码围栏嵌套。

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

frontend/src/utils/comment.ts

@@ -22,6 +22,22 @@ export function isGuestComment(c: Comment): boolean {
   return !c.user_id || c.user_id === 0;
 }
 
+/** 收集评论及其 reply_to 后代的 ID（含自身） */
+export function collectCommentSubtreeIds(comments: Comment[], rootId: number): Set<number> {
+  const ids = new Set<number>([rootId]);
+  let changed = true;
+  while (changed) {
+    changed = false;
+    for (const c of comments) {
+      if (!ids.has(c.id) && c.reply_to != null && ids.has(c.reply_to)) {
+        ids.add(c.id);
+        changed = true;
+      }
+    }
+  }
+  return ids;
+}
+
 /** 构建嵌套评论树（优先 thread_parent_id，回退 reply_to） */
 export function buildCommentTree(comments: Comment[]): CommentNode[] {
   const map = new Map<number, CommentNode>();

frontend/src/utils/enhanceCodeBlocks.ts

@@ -40,9 +40,47 @@ function readDisplayOptions(pre: Element) {
   };
 }
 
+/**
+ * 在换行处闭合并重开跨行 <span>，使每行 HTML 片段自包含。
+ * hljs token 常跨多行，直接按 \\n 切开会破坏标签导致行号布局叠字。
+ */
+function balanceHighlightLines(highlightedHtml: string): string[] {
+  const openTags: string[] = [];
+  let balanced = '';
+  const tokenRe = /(<span\b[^>]*>)|(<\/span>)|(\n)/g;
+  let lastIndex = 0;
+  let match: RegExpExecArray | null;
+
+  while ((match = tokenRe.exec(highlightedHtml)) !== null) {
+    balanced += highlightedHtml.slice(lastIndex, match.index);
+    lastIndex = tokenRe.lastIndex;
+
+    if (match[3] !== undefined) {
+      // 换行：先闭合当前栈，再于下一行重开
+      for (let i = openTags.length - 1; i >= 0; i--) balanced += '</span>';
+      balanced += '\n';
+      for (const tag of openTags) balanced += tag;
+      continue;
+    }
+
+    if (match[2] !== undefined) {
+      openTags.pop();
+      balanced += match[2];
+      continue;
+    }
+
+    // 开标签
+    openTags.push(match[1]);
+    balanced += match[1];
+  }
+
+  balanced += highlightedHtml.slice(lastIndex);
+  return balanced.split('\n');
+}
+
 /** 为高亮后的 HTML 按行包一层，便于行号与折叠计数 */
 function wrapCodeLines(highlightedHtml: string, withLineNumbers: boolean): string {
-  const lines = highlightedHtml.split('\n');
+  const lines = balanceHighlightLines(highlightedHtml);
   return lines
     .map((line, i) => {
       const num = i + 1;

frontend/src/utils/markdownContent.ts

@@ -3,6 +3,7 @@ import { marked } from 'marked';
 import DOMPurify from 'dompurify';
 import { POST_CONTENT_PURIFY_CONFIG } from './postContent';
 import { parseFenceInfo, formatFenceInfo } from './codeBlockOptions';
+import { mapOutsideFences, wrapFencedCode } from './markdownFences';
 
 const GATED_BLOCK_RE = /<(members-only|reply-only)(?:\s[^>]*)?>([\s\S]*?)<\/\1>/gi;
 
@@ -80,7 +81,7 @@ function addTurndownContentRules(service: TurndownService): void {
       const collapsed = pre.getAttribute('data-collapsed') === 'true'
         || wrap?.getAttribute('data-collapsed') === 'true';
       const info = formatFenceInfo({ language, lineNumbers, collapsed });
-      return `\n\n\`\`\`${info}\n${text}\n\`\`\`\n\n`;
+      return wrapFencedCode(info, text);
     },
   });
 
@@ -284,10 +285,9 @@ function sanitizeContentHtml(html: string): string {
 
 /** 将行首空格转为不换行空格，避免 HTML 折叠缩进；跳过围栏代码块 */
 function preserveLeadingIndent(markdown: string): string {
-  return markdown.split(/(```[\s\S]*?```)/g).map((part, index) => {
-    if (index % 2 === 1) return part;
-    return part.replace(/^( +)(?=\S)/gm, (_match, spaces: string) => '\u00A0'.repeat(spaces.length));
-  }).join('');
+  return mapOutsideFences(markdown, (outside) =>
+    outside.replace(/^( +)(?=\S)/gm, (_match, spaces: string) => '\u00A0'.repeat(spaces.length)),
+  );
 }
 
 /** 将普通 Markdown 片段转为 HTML */

frontend/src/utils/markdownFences.ts

@@ -0,0 +1,73 @@
+/** CommonMark 围栏：开围栏行（最多 3 空格缩进 + 至少 3 个反引号） */
+const OPEN_FENCE_RE = /^ {0,3}(`{3,})([^`\n]*)$/;
+/** 闭围栏行：仅反引号与可选尾随空白 */
+const CLOSE_FENCE_RE = /^ {0,3}(`{3,})[ \t]*$/;
+
+/** 正文中最长连续反引号数；外层围栏需至少 longest+1（且 ≥ 3） */
+export function fenceLengthForContent(text: string): number {
+  let longest = 0;
+  let run = 0;
+  for (let i = 0; i < text.length; i++) {
+    if (text[i] === '`') {
+      run += 1;
+      if (run > longest) longest = run;
+    } else {
+      run = 0;
+    }
+  }
+  return Math.max(3, longest + 1);
+}
+
+/** 用足够长的围栏包裹代码正文（info 为语言/选项串，可为空） */
+export function wrapFencedCode(info: string, text: string): string {
+  const len = fenceLengthForContent(text);
+  const fence = '`'.repeat(len);
+  const open = info ? `${fence}${info}` : fence;
+  return `\n\n${open}\n${text}\n${fence}\n\n`;
+}
+
+/**
+ * 按行识别围栏块；仅对围栏外文本调用 fn。
+ * 闭合条件：行首闭围栏长度 ≥ 开围栏（CommonMark）。
+ */
+export function mapOutsideFences(markdown: string, fn: (outside: string) => string): string {
+  const lines = markdown.split('\n');
+  const out: string[] = [];
+  let i = 0;
+  let outsideBuf: string[] = [];
+
+  const flushOutside = () => {
+    if (outsideBuf.length === 0) return;
+    out.push(fn(outsideBuf.join('\n')));
+    outsideBuf = [];
+  };
+
+  while (i < lines.length) {
+    const openMatch = lines[i].match(OPEN_FENCE_RE);
+    if (!openMatch) {
+      outsideBuf.push(lines[i]);
+      i += 1;
+      continue;
+    }
+
+    flushOutside();
+    const openLen = openMatch[1].length;
+    const fenceLines = [lines[i]];
+    i += 1;
+
+    while (i < lines.length) {
+      fenceLines.push(lines[i]);
+      const closeMatch = lines[i].match(CLOSE_FENCE_RE);
+      if (closeMatch && closeMatch[1].length >= openLen) {
+        i += 1;
+        break;
+      }
+      i += 1;
+    }
+
+    out.push(fenceLines.join('\n'));
+  }
+
+  flushOutside();
+  return out.join('\n');
+}