diff --git a/frontend/src/components/FloatingToc/FloatingToc.jsx b/frontend/src/components/FloatingToc/FloatingToc.jsx
index 58dd1b5..0ca2f98 100644
--- a/frontend/src/components/FloatingToc/FloatingToc.jsx
+++ b/frontend/src/components/FloatingToc/FloatingToc.jsx
@@ -18,7 +18,7 @@ function buildAnchorItems(items, searchKeyword, renderTitle) {
   }))
 }
 
-function TocContent({ items = [], getContainer, searchKeyword = '', renderTitle, onItemClick }) {
+function TocContent({ items = [], getContainer, searchKeyword = '', renderTitle, onItemClick, onNavigate }) {
   const anchorItems = buildAnchorItems(items, searchKeyword, renderTitle)
 
   return (
@@ -30,6 +30,12 @@ function TocContent({ items = [], getContainer, searchKeyword = '', renderTitle,
           getContainer={getContainer}
           items={anchorItems}
           onClick={(e, link) => {
+            // antd Anchor 的 link 为 { href, title } 对象
+            // 虚拟滚动场景下目标标题可能不在 DOM 中，由 onNavigate 接管滚动
+            if (onNavigate) {
+              e.preventDefault()
+              onNavigate(link?.href)
+            }
             window.setTimeout(() => onItemClick?.(link), 120)
           }}
         />
@@ -47,6 +53,7 @@ export function TocDrawer({
   getContainer,
   searchKeyword = '',
   renderTitle,
+  onNavigate,
 }) {
   return (
     <Drawer
@@ -63,6 +70,7 @@ export function TocDrawer({
         searchKeyword={searchKeyword}
         renderTitle={renderTitle}
         onItemClick={onClose}
+        onNavigate={onNavigate}
       />
     </Drawer>
   )
@@ -73,6 +81,7 @@ export default function FloatingToc({
   getContainer,
   searchKeyword = '',
   renderTitle,
+  onNavigate,
   className = '',
 }) {
   const [dismissed, setDismissed] = useState(false)
@@ -100,6 +109,7 @@ export default function FloatingToc({
           searchKeyword={searchKeyword}
           renderTitle={renderTitle}
           onItemClick={() => setDismissed(true)}
+          onNavigate={onNavigate}
         />
       </div>
     </aside>
diff --git a/frontend/src/components/LargeMarkdownViewer/LargeMarkdownEditor.css b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownEditor.css
new file mode 100644
index 0000000..b647a31
--- /dev/null
+++ b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownEditor.css
@@ -0,0 +1,99 @@
+/* 外框：与 ByteMD 编辑器一致的边框容器 */
+.large-markdown-editor {
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+  min-height: 0;
+  min-width: 0;
+  width: 100%;
+  height: 100%;
+  border: 1px solid var(--border-color);
+  border-radius: 2px;
+  overflow: hidden;
+  box-sizing: border-box;
+  background: var(--bg-color);
+}
+
+/* 顶部提示栏：复用 ByteMD 工具栏的视觉规范 */
+.large-markdown-editor-header {
+  flex-shrink: 0;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  height: 40px;
+  padding: 0 16px;
+  border-bottom: 1px solid var(--border-color);
+  background-color: var(--toolbar-bg);
+  color: var(--text-color-secondary);
+  font-size: 13px;
+  box-sizing: border-box;
+}
+
+.large-markdown-editor-header-icon {
+  color: var(--link-color);
+}
+
+/* 编辑区域 */
+.large-markdown-editor-body {
+  flex: 1;
+  min-height: 0;
+  min-width: 0;
+  overflow: hidden;
+}
+
+.large-markdown-editor-body .CodeMirror {
+  width: 100%;
+  height: 100%;
+  background: var(--bg-color);
+  color: var(--text-color);
+  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
+  font-size: 14px;
+  line-height: 1.8;
+}
+
+/* 左右内边距对称 */
+.large-markdown-editor-body .CodeMirror-lines {
+  padding: 12px 0;
+}
+
+.large-markdown-editor-body .CodeMirror pre.CodeMirror-line,
+.large-markdown-editor-body .CodeMirror pre.CodeMirror-line-like {
+  padding: 0 16px;
+}
+
+.large-markdown-editor-body .CodeMirror-cursor {
+  border-left-color: var(--text-color);
+}
+
+.large-markdown-editor-body .CodeMirror-placeholder {
+  color: var(--text-color-secondary);
+}
+
+.large-markdown-editor-body .CodeMirror-selected {
+  background: rgba(22, 119, 255, 0.16);
+}
+
+/* 暗色模式下覆盖 cm-s-default 的浅色配色，提升对比度 */
+body.dark .large-markdown-editor-body .CodeMirror-selected {
+  background: rgba(22, 119, 255, 0.28);
+}
+
+body.dark .large-markdown-editor-body .cm-s-default .cm-header {
+  color: #4ea1ff;
+}
+
+body.dark .large-markdown-editor-body .cm-s-default .cm-quote {
+  color: #6cc070;
+}
+
+body.dark .large-markdown-editor-body .cm-s-default .cm-link {
+  color: #58a6ff;
+}
+
+body.dark .large-markdown-editor-body .cm-s-default .cm-url {
+  color: #d2545b;
+}
+
+body.dark .large-markdown-editor-body .cm-s-default .cm-variable-2 {
+  color: #79b8ff;
+}
diff --git a/frontend/src/components/LargeMarkdownViewer/LargeMarkdownEditor.jsx b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownEditor.jsx
new file mode 100644
index 0000000..c7134b1
--- /dev/null
+++ b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownEditor.jsx
@@ -0,0 +1,90 @@
+import { useEffect, useRef } from 'react'
+import { InfoCircleOutlined } from '@ant-design/icons'
+import factory from 'codemirror-ssr'
+import usePlaceholder from 'codemirror-ssr/addon/display/placeholder.js'
+import useContinuelist from 'codemirror-ssr/addon/edit/continuelist.js'
+import useOverlay from 'codemirror-ssr/addon/mode/overlay.js'
+import useGfm from 'codemirror-ssr/mode/gfm/gfm.js'
+import useMarkdown from 'codemirror-ssr/mode/markdown/markdown.js'
+import useXml from 'codemirror-ssr/mode/xml/xml.js'
+import 'codemirror-ssr/lib/codemirror.css'
+import { LARGE_MARKDOWN_NOTICE } from './LargeMarkdownViewer'
+import './LargeMarkdownEditor.css'
+
+// 复用 ByteMD 底层的 codemirror-ssr，为超大文档提供带 Markdown 源码着色的纯文本编辑器。
+// 不引入新依赖，CodeMirror 5 的视口渲染让超大文档编辑保持流畅。
+function createCodeMirror() {
+  const codemirror = factory()
+  usePlaceholder(codemirror)
+  useOverlay(codemirror)
+  useXml(codemirror)
+  useMarkdown(codemirror)
+  useGfm(codemirror)
+  useContinuelist(codemirror)
+  return codemirror
+}
+
+export default function LargeMarkdownEditor({ value = '', onChange, placeholder = '' }) {
+  const containerRef = useRef(null)
+  const editorRef = useRef(null)
+  const onChangeRef = useRef(onChange)
+
+  // 保持 onChange 最新，但不因其变化而重建编辑器
+  useEffect(() => {
+    onChangeRef.current = onChange
+  }, [onChange])
+
+  useEffect(() => {
+    if (!containerRef.current) return
+
+    const codemirror = createCodeMirror()
+    const editor = codemirror(containerRef.current, {
+      value,
+      mode: 'gfm',
+      lineWrapping: true,
+      lineNumbers: false,
+      tabSize: 2,
+      indentUnit: 2,
+      placeholder,
+      extraKeys: {
+        Enter: 'newlineAndIndentContinueMarkdownList',
+        Tab: 'indentMore',
+        'Shift-Tab': 'indentLess',
+      },
+    })
+
+    editor.on('change', () => {
+      onChangeRef.current?.(editor.getValue())
+    })
+
+    editorRef.current = editor
+
+    return () => {
+      // 卸载时清理 CodeMirror 实例的 DOM
+      const wrapper = editor.getWrapperElement()
+      wrapper?.parentNode?.removeChild(wrapper)
+      editorRef.current = null
+    }
+  }, [])
+
+  // 外部 value 变化（切换文件、重置）时同步，避免覆盖正在输入的光标位置
+  useEffect(() => {
+    const editor = editorRef.current
+    if (!editor) return
+    if (value !== editor.getValue()) {
+      const cursor = editor.getCursor()
+      editor.setValue(value)
+      editor.setCursor(cursor)
+    }
+  }, [value])
+
+  return (
+    <div className="large-markdown-editor">
+      <div className="large-markdown-editor-header">
+        <InfoCircleOutlined className="large-markdown-editor-header-icon" />
+        <span>{LARGE_MARKDOWN_NOTICE}</span>
+      </div>
+      <div className="large-markdown-editor-body" ref={containerRef} />
+    </div>
+  )
+}
diff --git a/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.css b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.css
index 5a8befc..635d42b 100644
--- a/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.css
+++ b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.css
@@ -39,15 +39,35 @@
   padding: 0 0 1px;
 }
 
+/* 首块下移，避免被固定浮动的提示窗遮挡 */
+.markdown-block[data-index='0'] {
+  padding-top: 64px;
+}
+
+/* 虚拟滚动条更纤细，减少视觉割裂 */
+.markdown-virtual-list::-webkit-scrollbar {
+  width: 10px;
+}
+
+.markdown-virtual-list::-webkit-scrollbar-thumb {
+  background: color-mix(in srgb, var(--text-color-secondary) 28%, transparent);
+  border-radius: 999px;
+  border: 3px solid transparent;
+  background-clip: padding-box;
+}
+
+.markdown-virtual-list::-webkit-scrollbar-thumb:hover {
+  background: color-mix(in srgb, var(--text-color-secondary) 44%, transparent);
+  background-clip: padding-box;
+}
+
 @media (max-width: 768px) {
-  .large-markdown-notice,
   .markdown-block {
     width: calc(100% - 32px);
   }
 }
 
 @media (max-width: 480px) {
-  .large-markdown-notice,
   .markdown-block {
     width: calc(100% - 24px);
   }
diff --git a/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.jsx b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.jsx
index 7d08a3a..5076589 100644
--- a/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.jsx
+++ b/frontend/src/components/LargeMarkdownViewer/LargeMarkdownViewer.jsx
@@ -5,10 +5,14 @@ import ReactMarkdown from 'react-markdown'
 import remarkGfm from 'remark-gfm'
 import rehypeRaw from 'rehype-raw'
 import rehypeSlug from 'rehype-slug'
+import rehypeHighlight from 'rehype-highlight'
+import GithubSlugger from 'github-slugger'
+import FloatingToc from '@/components/FloatingToc/FloatingToc'
 import './LargeMarkdownViewer.css'
 
 export const LARGE_MARKDOWN_THRESHOLD = 250000
 export const LARGE_MARKDOWN_NOTICE = '此文档内容过长，将采用精简模式显示'
+const MAX_TOC_ITEMS = 500
 
 export function isLargeMarkdownContent(content = '') {
   return content.length > LARGE_MARKDOWN_THRESHOLD
@@ -27,10 +31,14 @@ export function MarkdownSizeNotice({ className = '' }) {
   )
 }
 
-function splitMarkdownIntoBlocks(content) {
-  if (!content) return []
+// 将 markdown 切分为块，并在切分的同时提取标题用于目录导航。
+// 每个块以标题或空行为边界，目录项记录其所在块索引，便于虚拟滚动定位。
+function buildBlocksAndToc(content) {
+  if (!content) return { blocks: [], tocItems: [] }
 
   const blocks = []
+  const tocItems = []
+  const slugger = new GithubSlugger()
   const lines = content.split('\n')
   let current = []
   let inFence = false
@@ -44,10 +52,20 @@ function splitMarkdownIntoBlocks(content) {
 
   for (const line of lines) {
     const isFenceLine = /^\s*(```|~~~)/.test(line)
-    const isHeading = /^(#{1,6})\s+/.test(line)
+    const headingMatch = inFence ? null : line.match(/^(#{1,6})\s+(.+)$/)
 
-    if (!inFence && isHeading) {
+    if (headingMatch) {
       flush()
+      if (tocItems.length < MAX_TOC_ITEMS) {
+        const key = slugger.slug(headingMatch[2].trim())
+        tocItems.push({
+          key: `#${key}`,
+          href: `#${key}`,
+          title: headingMatch[2].trim(),
+          level: headingMatch[1].length,
+          blockIndex: blocks.length, // 该标题即将进入的块的索引
+        })
+      }
     }
 
     current.push(line)
@@ -62,23 +80,48 @@ function splitMarkdownIntoBlocks(content) {
   }
 
   flush()
-  return blocks
+  return { blocks, tocItems }
 }
 
-const LargeMarkdownViewer = forwardRef(function LargeMarkdownViewer({ content, components, onClick }, ref) {
+const LargeMarkdownViewer = forwardRef(function LargeMarkdownViewer(
+  { content, components, onClick, searchKeyword = '', renderTitle },
+  ref
+) {
   const virtuosoRef = useRef(null)
-  const markdownBlocks = useMemo(() => splitMarkdownIntoBlocks(content), [content])
+  const { blocks: markdownBlocks, tocItems } = useMemo(
+    () => buildBlocksAndToc(content),
+    [content]
+  )
+
+  const hrefToIndex = useMemo(() => {
+    const map = new Map()
+    for (const item of tocItems) {
+      if (!map.has(item.href)) {
+        map.set(item.href, item.blockIndex)
+      }
+    }
+    return map
+  }, [tocItems])
+
+  const scrollToIndex = (index) => {
+    virtuosoRef.current?.scrollToIndex({
+      index,
+      align: 'start',
+      behavior: 'smooth',
+    })
+  }
 
   useImperativeHandle(ref, () => ({
-    scrollToTop: () => {
-      virtuosoRef.current?.scrollToIndex({
-        index: 0,
-        align: 'start',
-        behavior: 'smooth',
-      })
-    },
+    scrollToTop: () => scrollToIndex(0),
   }), [])
 
+  const handleTocNavigate = (link) => {
+    const index = hrefToIndex.get(link)
+    if (typeof index === 'number') {
+      scrollToIndex(index)
+    }
+  }
+
   return (
     <div className="large-markdown-viewer">
       <MarkdownSizeNotice />
@@ -91,7 +134,7 @@ const LargeMarkdownViewer = forwardRef(function LargeMarkdownViewer({ content, c
             <div className="markdown-block" data-index={index}>
               <ReactMarkdown
                 remarkPlugins={[remarkGfm]}
-                rehypePlugins={[rehypeRaw, rehypeSlug]}
+                rehypePlugins={[rehypeRaw, rehypeSlug, rehypeHighlight]}
                 components={components}
               >
                 {block}
@@ -100,6 +143,12 @@ const LargeMarkdownViewer = forwardRef(function LargeMarkdownViewer({ content, c
           )}
         />
       </div>
+      <FloatingToc
+        items={tocItems}
+        searchKeyword={searchKeyword}
+        renderTitle={renderTitle}
+        onNavigate={handleTocNavigate}
+      />
     </div>
   )
 })
diff --git a/frontend/src/components/MainLayout/MainLayout.jsx b/frontend/src/components/MainLayout/MainLayout.jsx
index 726c328..2603908 100644
--- a/frontend/src/components/MainLayout/MainLayout.jsx
+++ b/frontend/src/components/MainLayout/MainLayout.jsx
@@ -1,4 +1,5 @@
-import { useState } from 'react'
+import { useState, useEffect } from 'react'
+import { useLocation } from 'react-router-dom'
 import { Layout } from 'antd'
 import AppSider from './AppSider'
 import AppHeader from './AppHeader'
@@ -6,9 +7,19 @@ import './MainLayout.css'
 
 const { Content } = Layout
 
+// 进入项目文档页/编辑页时自动折叠全局侧边栏，给文档内容腾出空间
+const COLLAPSE_PATTERNS = [/^\/projects\/[^/]+\/docs/, /^\/projects\/[^/]+\/editor/]
+
 function MainLayout({ children }) {
+  const location = useLocation()
   const [collapsed, setCollapsed] = useState(false)
 
+  useEffect(() => {
+    if (COLLAPSE_PATTERNS.some((pattern) => pattern.test(location.pathname))) {
+      setCollapsed(true)
+    }
+  }, [location.pathname])
+
   const toggleCollapsed = () => {
     setCollapsed(!collapsed)
   }
diff --git a/frontend/src/pages/Document/DocumentEditor.css b/frontend/src/pages/Document/DocumentEditor.css
index e9ae3a1..4ab51a4 100644
--- a/frontend/src/pages/Document/DocumentEditor.css
+++ b/frontend/src/pages/Document/DocumentEditor.css
@@ -236,15 +236,12 @@
 
 .bytemd-wrapper.large-file-editor {
   position: relative;
-  padding: 0;
+  display: flex;
+  flex-direction: column;
 }
 
-.large-file-editor-notice {
-  top: 12px;
-}
-
-/* Fix for bytemd-react wrapper div */
-.bytemd-wrapper>div {
+/* Fix for bytemd-react wrapper div（仅普通编辑器，超大着色编辑器不受此约束） */
+.bytemd-wrapper:not(.large-file-editor)>div {
   flex: 1;
   display: flex;
   flex-direction: column;
@@ -253,36 +250,6 @@
   min-width: 0;
 }
 
-.bytemd-wrapper.large-file-editor>.large-markdown-notice {
-  flex: none !important;
-  display: block !important;
-  width: min(920px, calc(100% - 48px)) !important;
-  height: auto !important;
-  min-height: 0 !important;
-}
-
-.large-markdown-textarea {
-  flex: 1;
-  width: 100%;
-  height: 100%;
-  min-height: 0;
-  resize: none;
-  border: 1px solid var(--border-color);
-  border-radius: 2px;
-  padding: 64px 16px 16px;
-  background: var(--bg-color);
-  color: var(--text-color);
-  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
-  font-size: 14px;
-  line-height: 1.8;
-  outline: none;
-}
-
-.large-markdown-textarea:focus {
-  border-color: #1677ff;
-  box-shadow: 0 0 0 2px rgba(22, 119, 255, 0.15);
-}
-
 .empty-editor {
   height: 100%;
   display: flex;
diff --git a/frontend/src/pages/Document/DocumentEditor.jsx b/frontend/src/pages/Document/DocumentEditor.jsx
index 7b3348f..7fc7e4a 100644
--- a/frontend/src/pages/Document/DocumentEditor.jsx
+++ b/frontend/src/pages/Document/DocumentEditor.jsx
@@ -38,7 +38,8 @@ import {
 } from '@/api/file'
 import Toast from '@/components/Toast/Toast'
 import ModeSwitch from '@/components/ModeSwitch/ModeSwitch'
-import { MarkdownSizeNotice, isLargeMarkdownContent } from '@/components/LargeMarkdownViewer/LargeMarkdownViewer'
+import { isLargeMarkdownContent } from '@/components/LargeMarkdownViewer/LargeMarkdownViewer'
+import LargeMarkdownEditor from '@/components/LargeMarkdownViewer/LargeMarkdownEditor'
 import './DocumentEditor.css'
 
 const { Sider, Content } = Layout
@@ -1192,15 +1193,10 @@ function DocumentEditor() {
                 onDragOver={(e) => e.preventDefault()}
               >
                 {isLargeMarkdown ? (
-                  <>
-                    <MarkdownSizeNotice className="large-file-editor-notice" />
-                    <textarea
-                      className="large-markdown-textarea"
-                      value={fileContent}
-                      onChange={(e) => setFileContent(e.target.value)}
-                      spellCheck={false}
-                    />
-                  </>
+                  <LargeMarkdownEditor
+                    value={fileContent}
+                    onChange={setFileContent}
+                  />
                 ) : (
                   <Editor
                     key={selectedFile}
diff --git a/frontend/src/pages/Document/DocumentPage.jsx b/frontend/src/pages/Document/DocumentPage.jsx
index 181afb6..5c689c6 100644
--- a/frontend/src/pages/Document/DocumentPage.jsx
+++ b/frontend/src/pages/Document/DocumentPage.jsx
@@ -1160,6 +1160,8 @@ function DocumentPage() {
                   ref={largeMarkdownRef}
                   content={markdownContent}
                   components={markdownComponents}
+                  searchKeyword={searchKeyword}
+                  renderTitle={(item, keyword) => <HighlightText text={item.title} keyword={keyword} />}
                 />
               ) : (
                 <div className="markdown-body">
diff --git a/frontend/src/pages/Preview/ProjectSharePage.jsx b/frontend/src/pages/Preview/ProjectSharePage.jsx
index a41a507..d6c305e 100644
--- a/frontend/src/pages/Preview/ProjectSharePage.jsx
+++ b/frontend/src/pages/Preview/ProjectSharePage.jsx
@@ -607,6 +607,8 @@ function ProjectSharePage() {
                   ref={largeMarkdownRef}
                   content={markdownContent}
                   components={markdownComponents}
+                  searchKeyword={searchKeyword}
+                  renderTitle={(item, keyword) => <HighlightText text={item.title} keyword={keyword} />}
                   onClick={(e) => {
                     if (e.defaultPrevented) return
                     const target = e.target.closest('a')