diff --git a/frontend/src/lib/components/DocumentViewer.svelte b/frontend/src/lib/components/DocumentViewer.svelte
index 5aa4b5b..ee4f3f4 100644
--- a/frontend/src/lib/components/DocumentViewer.svelte
+++ b/frontend/src/lib/components/DocumentViewer.svelte
@@ -7,8 +7,11 @@
   import Tabs from '$lib/components/ui/Tabs.svelte';
   import MarkdownDoc from '$lib/components/MarkdownDoc.svelte';
   import MarkdownStatusBadge from '$lib/components/MarkdownStatusBadge.svelte';
+  import SectionOutline from '$lib/components/SectionOutline.svelte';
   import { getViewerType } from '$lib/utils/viewerType';
   import { isMdSuccess } from '$lib/utils/mdStatus';
+  import { buildAnchorMap } from '$lib/utils/outlineAnchors';
+  import { cleanHeading } from '$lib/utils/headingPath';
 
   // 편집 미리보기 전용 plain marked (본문 렌더는 MarkdownDoc 가 담당).
   marked.use({ mangle: false, headerIds: false });
@@ -52,9 +55,11 @@
   async function loadFullDoc(id) {
     loading = true;
     rawMarkdown = '';
+    sections = [];
     try {
       fullDoc = await api(`/documents/${id}`);
       viewerType = getViewerType(fullDoc.file_format, fullDoc.source_channel);
+      loadSections(id);
 
       // 본문 markdown(md/txt) 인데 extracted_text 가 비면 원본 파일 직접 로드.
       if (viewerType === 'markdown' && !fullDoc.extracted_text) {
@@ -88,6 +93,69 @@
     if (!canShowMarkdown && pdfViewMode === 'markdown') pdfViewMode = 'pdf';
   });
 
+  // ── 절 목차(개요) rail + 점프 + scroll-spy (outlineAnchors, 경로 A) ──
+  let sections = $state([]);
+  async function loadSections(id) {
+    try {
+      const r = await api(`/documents/${id}/sections`);
+      if (id === doc?.id) sections = r?.sections ?? [];
+    } catch {
+      if (id === doc?.id) sections = [];
+    }
+  }
+  // window 빈제목(31% 노이즈) 등 표시 가능한 제목 없는 항목은 rail 에서 제외(클린업).
+  let outlineSections = $derived(
+    sections.filter(
+      (s) => !!(cleanHeading(s.section_title) || cleanHeading((s.heading_path || '').split('>').pop() || '')),
+    ),
+  );
+  // MarkdownDoc 가 실제 렌더하는 텍스트(anchor offset 기준과 일치해야 함).
+  let mdRenderText = $derived.by(() => {
+    if (!fullDoc) return '';
+    if (viewerType === 'pdf') return pdfViewMode === 'markdown' && canShowMarkdown ? (fullDoc.md_content || '') : '';
+    if (viewerType === 'markdown') return fullDoc.extracted_text || rawMarkdown || '';
+    if (viewerType === 'hwp-markdown' || viewerType === 'article') return fullDoc.md_content || fullDoc.extracted_text || '';
+    return '';
+  });
+  let anchorMap = $derived(sections.length && mdRenderText ? buildAnchorMap(mdRenderText, sections).anchors : {});
+  let showRail = $derived(outlineSections.length > 0 && !!mdRenderText);
+
+  let scrollEl = $state();
+  let activeKey = $state(null);
+  function jumpTo(chunkId) {
+    const el = scrollEl?.querySelector(`#sec-${chunkId}`);
+    if (el) el.scrollIntoView({ block: 'start', behavior: 'smooth' });
+  }
+  // scroll-spy: scrollEl 내 .md-anchor 중 컨테이너 상단(+120) 지난 마지막 = 현재 절.
+  $effect(() => {
+    void anchorMap;
+    const el = scrollEl;
+    if (!el) return;
+    let raf = 0;
+    const onScroll = () => {
+      if (raf) return;
+      raf = requestAnimationFrame(() => {
+        raf = 0;
+        const threshold = el.getBoundingClientRect().top + 120;
+        let cur = null;
+        el.querySelectorAll('.md-anchor').forEach((a) => {
+          if (a.getBoundingClientRect().top <= threshold) cur = a;
+        });
+        if (cur) {
+          const m = cur.id.match(/^sec-(\d+)$/);
+          if (m) activeKey = Number(m[1]);
+        }
+      });
+    };
+    el.addEventListener('scroll', onScroll, { passive: true });
+    const t = setTimeout(onScroll, 0);
+    return () => {
+      el.removeEventListener('scroll', onScroll);
+      clearTimeout(t);
+      if (raf) cancelAnimationFrame(raf);
+    };
+  });
+
   function startEdit() {
     editContent = fullDoc?.extracted_text || rawMarkdown || '';
     editMode = true;
@@ -152,8 +220,14 @@
     </div>
   {/if}
 
-  <!-- 뷰어 본문 -->
-  <div class="flex-1 overflow-auto min-h-0">
+  <!-- 뷰어 본문 (+ 절 목차 rail) -->
+  <div class="flex-1 flex min-h-0">
+    {#if showRail}
+      <aside class="hidden lg:block w-[176px] shrink-0 overflow-y-auto border-r border-default p-2 bg-sidebar">
+        <SectionOutline sections={outlineSections} onJump={jumpTo} {activeKey} />
+      </aside>
+    {/if}
+    <div class="flex-1 overflow-auto min-h-0" bind:this={scrollEl}>
     {#if loading}
       <div class="flex items-center justify-center h-full"><p class="text-sm text-dim">로딩 중...</p></div>
     {:else if fullDoc}
@@ -181,14 +255,15 @@
               mdStatus={fullDoc.md_status}
               mdExtractionError={fullDoc.md_extraction_error}
               mdExtractionQuality={fullDoc.md_extraction_quality}
+              anchorMap={anchorMap}
               extractedText={fullDoc.extracted_text || rawMarkdown}
               class={PROSE}
             />
           </div>
         {/if}
       {:else if viewerType === 'pdf'}
-        <div class="p-4 flex flex-col h-full">
-          <div class="mb-2 flex items-center gap-2 shrink-0">
+        <div class="p-4">
+          <div class="mb-2 flex items-center gap-2">
             <MarkdownStatusBadge mdStatus={fullDoc.md_status} mdExtractionError={fullDoc.md_extraction_error} mdExtractionQuality={fullDoc.md_extraction_quality} />
             {#if canShowMarkdown}
               <button onclick={() => (pdfViewMode = 'markdown')}
@@ -198,20 +273,19 @@
             {/if}
           </div>
           {#if pdfViewMode === 'markdown' && canShowMarkdown}
-            <div class="flex-1 overflow-auto">
-              <MarkdownDoc
-                documentId={fullDoc.id}
-                mdContent={fullDoc.md_content}
-                mdFrontmatter={fullDoc.md_frontmatter}
-                mdStatus={fullDoc.md_status}
-                mdExtractionError={fullDoc.md_extraction_error}
-                mdExtractionQuality={fullDoc.md_extraction_quality}
-                extractedText={fullDoc.extracted_text}
-                class={PROSE}
-              />
-            </div>
+            <MarkdownDoc
+              documentId={fullDoc.id}
+              mdContent={fullDoc.md_content}
+              mdFrontmatter={fullDoc.md_frontmatter}
+              mdStatus={fullDoc.md_status}
+              mdExtractionError={fullDoc.md_extraction_error}
+              mdExtractionQuality={fullDoc.md_extraction_quality}
+              anchorMap={anchorMap}
+              extractedText={fullDoc.extracted_text}
+              class={PROSE}
+            />
           {:else}
-            <iframe src="/api/documents/{fullDoc.id}/file?token={getAccessToken()}" class="flex-1 w-full border-0 rounded" title={fullDoc.title}></iframe>
+            <iframe src="/api/documents/{fullDoc.id}/file?token={getAccessToken()}" class="w-full h-[80vh] border-0 rounded" title={fullDoc.title}></iframe>
           {/if}
         </div>
       {:else if viewerType === 'hwp-markdown'}
@@ -281,5 +355,6 @@
         <div class="flex items-center justify-center h-full"><p class="text-sm text-dim">미리보기를 지원하지 않는 형식입니다 ({fullDoc.file_format})</p></div>
       {/if}
     {/if}
+    </div>
   </div>
 </div>