diff --git a/app/api/documents.py b/app/api/documents.py
index 2e39473..920bb7d 100644
--- a/app/api/documents.py
+++ b/app/api/documents.py
@@ -124,6 +124,22 @@ class DocumentListResponse(BaseModel):
     page_size: int
 
 
+class DocumentDetailResponse(DocumentResponse):
+    """단건 조회 전용 — 본문(extracted_text)·canonical markdown 동봉.
+    리스트 응답은 페이로드 비대화 회피로 DocumentResponse 만 사용.
+    """
+
+    extracted_text: str | None = None
+    md_content: str | None = None
+    md_frontmatter: dict | None = None
+    md_status: str | None = None
+    md_extraction_quality: dict | None = None
+    md_extraction_error: str | None = None
+    md_extraction_engine: str | None = None
+    md_extraction_engine_version: str | None = None
+    md_generated_at: datetime | None = None
+
+
 class AcceptSuggestionRequest(BaseModel):
     """§1 accept-suggestion 요청 body — stale payload / doc 수정 검출."""
     expected_source_updated_at: datetime
@@ -507,17 +523,17 @@ async def list_documents(
     )
 
 
-@router.get("/{doc_id}", response_model=DocumentResponse)
+@router.get("/{doc_id}", response_model=DocumentDetailResponse)
 async def get_document(
     doc_id: int,
     user: Annotated[User, Depends(get_current_user)],
     session: Annotated[AsyncSession, Depends(get_session)],
 ):
-    """문서 단건 조회"""
+    """문서 단건 조회. 본문(extracted_text)·canonical markdown 동봉."""
     doc = await session.get(Document, doc_id)
     if not doc or doc.deleted_at is not None:
         raise HTTPException(status_code=404, detail="문서를 찾을 수 없습니다")
-    return DocumentResponse.model_validate(doc)
+    return DocumentDetailResponse.model_validate(doc)
 
 
 # ─── 자료실 인접 자료 (이전/다음) ───
diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 688f728..f9e1b12 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -12,6 +12,7 @@
         "katex": "^0.16.45",
         "lucide-svelte": "^0.400.0",
         "marked": "^15.0.0",
+        "marked-gfm-heading-id": "^4.1.4",
         "marked-katex-extension": "^5.1.8",
         "perfect-freehand": "^1.2.3"
       },
@@ -1444,6 +1445,12 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/github-slugger": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/github-slugger/-/github-slugger-2.0.0.tgz",
+      "integrity": "sha512-IaOQ9puYtjrkq7Y0Ygl9KDZnrf/aiUJYUpVf89y8kyaxbRG7Y1SrX/jaumrv81vc61+kiMempujsM3Yw7w5qcw==",
+      "license": "ISC"
+    },
     "node_modules/graceful-fs": {
       "version": "4.2.11",
       "resolved": "https://registry.npmjs.org/graceful-fs/-/graceful-fs-4.2.11.tgz",
@@ -1830,6 +1837,18 @@
         "node": ">= 18"
       }
     },
+    "node_modules/marked-gfm-heading-id": {
+      "version": "4.1.4",
+      "resolved": "https://registry.npmjs.org/marked-gfm-heading-id/-/marked-gfm-heading-id-4.1.4.tgz",
+      "integrity": "sha512-CspnvVfHSkb/znqdPS4jUR8HtCjq3M/DnrsJCrfLBLvdrgbemmoINKpeWKQYkBiXAoBGejw0cV7xzqrPdup3WA==",
+      "license": "MIT",
+      "dependencies": {
+        "github-slugger": "^2.0.0"
+      },
+      "peerDependencies": {
+        "marked": ">=13 <19"
+      }
+    },
     "node_modules/marked-katex-extension": {
       "version": "5.1.8",
       "resolved": "https://registry.npmjs.org/marked-katex-extension/-/marked-katex-extension-5.1.8.tgz",
diff --git a/frontend/package.json b/frontend/package.json
index 36ff279..6d3f040 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -22,6 +22,7 @@
     "katex": "^0.16.45",
     "lucide-svelte": "^0.400.0",
     "marked": "^15.0.0",
+    "marked-gfm-heading-id": "^4.1.4",
     "marked-katex-extension": "^5.1.8",
     "perfect-freehand": "^1.2.3"
   }
diff --git a/frontend/src/app.css b/frontend/src/app.css
index c40f163..267f62d 100644
--- a/frontend/src/app.css
+++ b/frontend/src/app.css
@@ -139,3 +139,46 @@ body {
 .math-area p { margin: 0.5em 0; }
 .math-area p:first-child { margin-top: 0; }
 .math-area p:last-child { margin-bottom: 0; }
+
+/* Phase 1C: MarkdownDoc — heading anchor / figure caption / KaTeX 가로 스크롤 */
+.markdown-doc { overflow-wrap: anywhere; }
+.markdown-doc h1, .markdown-doc h2, .markdown-doc h3,
+.markdown-doc h4, .markdown-doc h5, .markdown-doc h6 {
+  scroll-margin-top: 80px;
+  position: relative;
+}
+.markdown-doc .heading-anchor {
+  display: inline-block;
+  margin-right: 0.35em;
+  color: var(--text-dim);
+  font-weight: 400;
+  text-decoration: none;
+  opacity: 0;
+  transition: opacity 0.15s;
+  font-family: 'SF Mono', Menlo, monospace;
+}
+.markdown-doc h1:hover .heading-anchor,
+.markdown-doc h2:hover .heading-anchor,
+.markdown-doc h3:hover .heading-anchor,
+.markdown-doc h4:hover .heading-anchor,
+.markdown-doc h5:hover .heading-anchor,
+.markdown-doc h6:hover .heading-anchor,
+.markdown-doc .heading-anchor:focus { opacity: 1; }
+.markdown-doc .heading-anchor:hover { color: var(--accent); }
+
+.markdown-doc .md-figure {
+  margin: 1em 0;
+  text-align: center;
+}
+.markdown-doc .md-figure img { display: inline-block; max-width: 100%; }
+.markdown-doc .md-figure figcaption {
+  margin-top: 0.4em;
+  font-size: 0.85em;
+  color: var(--text-dim);
+  font-style: italic;
+}
+.markdown-doc .katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.25em 0; }
+.markdown-doc .katex-display > .katex { white-space: nowrap; }
+
+/* Phase 1C: frontmatter 박스 — 본문 위 메타 표시 */
+.md-frontmatter dt { font-weight: 500; }
diff --git a/frontend/src/lib/components/MarkdownDoc.svelte b/frontend/src/lib/components/MarkdownDoc.svelte
new file mode 100644
index 0000000..2740c74
--- /dev/null
+++ b/frontend/src/lib/components/MarkdownDoc.svelte
@@ -0,0 +1,124 @@
+<script lang="ts">
+  /**
+   * 문서 본문 canonical markdown 렌더러 (Phase 1C).
+   *
+   * 우선순위:
+   *   1. md_content (Phase 1B 의 marker_worker 가 채운 canonical markdown)
+   *   2. extracted_text fallback (기존 본문)
+   *   3. placeholder
+   *
+   * 기능:
+   *   - md_frontmatter (JSONB) 가 비어있지 않으면 본문 위에 메타 박스
+   *   - heading anchor (h1~h6 id 자동 부여 + # 링크)
+   *   - figure caption (이미지 alt 있을 때)
+   *   - KaTeX ($...$ inline / $$...$$ block)
+   *   - DOMPurify sanitize
+   *
+   * 이미지 ImgAuth wiring 은 Phase 1B.5 후 추가 — 현재는 marker 출력 그대로 (data-md-img="1" 마킹만).
+   */
+  import { renderDocMarkdown } from '$lib/utils/docMarkdown';
+
+  type Props = {
+    mdContent?: string | null;
+    mdFrontmatter?: Record<string, unknown> | null;
+    extractedText?: string | null;
+    mdStatus?: string | null;
+    mdExtractionError?: string | null;
+    placeholder?: string;
+    /** 추가 래퍼 클래스. tailwind prose-* / spacing 등을 호출 측에서 입혀야 할 때. */
+    class?: string;
+  };
+
+  let {
+    mdContent = null,
+    mdFrontmatter = null,
+    extractedText = null,
+    mdStatus = null,
+    mdExtractionError = null,
+    placeholder = '*텍스트 추출 대기 중*',
+    class: klass = '',
+  }: Props = $props();
+
+  let usingMarkdown = $derived(!!(mdContent && mdContent.trim()));
+  let body = $derived(
+    usingMarkdown
+      ? (mdContent as string)
+      : extractedText && extractedText.trim()
+        ? extractedText
+        : placeholder,
+  );
+  let renderedHtml = $derived(renderDocMarkdown(body));
+
+  let frontmatterEntries = $derived.by(() => {
+    if (!usingMarkdown || !mdFrontmatter) return [] as [string, unknown][];
+    return Object.entries(mdFrontmatter).filter(
+      ([, v]) => v !== null && v !== undefined && v !== '',
+    );
+  });
+
+  let showFailureBadge = $derived(!usingMarkdown && mdStatus === 'failed');
+
+  function formatValue(v: unknown): string {
+    if (v === null || v === undefined) return '';
+    if (typeof v === 'object') {
+      try {
+        return JSON.stringify(v);
+      } catch {
+        return String(v);
+      }
+    }
+    return String(v);
+  }
+
+  let containerRef: HTMLDivElement | undefined = $state();
+
+  // heading anchor 후처리 — gfmHeadingId 가 부여한 id 에 # 링크 prepend.
+  // string-level 정규식 처리 대신 DOM 후처리 — id 에 따옴표/HTML 메타 들어와도 안전.
+  $effect(() => {
+    // renderedHtml 변할 때마다 재실행
+    void renderedHtml;
+    if (!containerRef) return;
+    const headings = containerRef.querySelectorAll<HTMLHeadingElement>(
+      'h1[id], h2[id], h3[id], h4[id], h5[id], h6[id]',
+    );
+    for (const h of headings) {
+      if (h.querySelector('a.heading-anchor')) continue;
+      const id = h.getAttribute('id');
+      if (!id) continue;
+      const a = document.createElement('a');
+      a.className = 'heading-anchor';
+      a.setAttribute('href', `#${id}`);
+      a.setAttribute('aria-label', '이 항목으로 링크');
+      a.textContent = '#';
+      h.insertBefore(a, h.firstChild);
+    }
+  });
+</script>
+
+{#if frontmatterEntries.length}
+  <dl
+    class="md-frontmatter mb-4 grid grid-cols-[max-content,1fr] gap-x-3 gap-y-1 rounded border border-border/60 bg-bg/40 px-4 py-3 text-xs"
+  >
+    <div class="col-span-2 mb-1 text-[10px] uppercase tracking-wide text-dim">메타</div>
+    {#each frontmatterEntries as [k, v] (k)}
+      <dt class="text-dim">{k}</dt>
+      <dd class="break-words text-text">{formatValue(v)}</dd>
+    {/each}
+  </dl>
+{/if}
+
+{#if showFailureBadge}
+  <div
+    class="mb-3 inline-flex items-center gap-2 rounded border border-warn/40 bg-warn/10 px-2 py-1 text-[10px] text-warn"
+    title={mdExtractionError ?? undefined}
+  >
+    Markdown 변환 실패 — 원본 추출 텍스트 표시
+  </div>
+{/if}
+
+<div
+  bind:this={containerRef}
+  class="markdown-body markdown-doc leading-relaxed {klass}"
+>
+  {@html renderedHtml}
+</div>
diff --git a/frontend/src/lib/utils/docMarkdown.ts b/frontend/src/lib/utils/docMarkdown.ts
new file mode 100644
index 0000000..b4e4839
--- /dev/null
+++ b/frontend/src/lib/utils/docMarkdown.ts
@@ -0,0 +1,76 @@
+/**
+ * 문서 본문 markdown 렌더 (Phase 1C — MarkdownDoc 컴포넌트 전용).
+ *
+ * mathMarkdown.ts (study 의 문제·해설용) 와 별도 인스턴스를 둬서 study 측 동작에 영향 없음.
+ *
+ * 차이점:
+ *   - GFM heading id (anchor 용 id 자동 부여, prefix=doc-)
+ *   - 이미지 token 을 figure + figcaption 으로 감싸기 (alt 있을 때)
+ *   - 모든 <img> 에 data-md-img="1" 마킹 — Phase 1B.5 에서 ImgAuth 후처리 selector 로 사용
+ *
+ * KaTeX / DOMPurify 정책은 mathMarkdown.ts 의 정책과 동일.
+ */
+
+import DOMPurify from 'dompurify';
+import { Marked } from 'marked';
+// @ts-ignore — 타입 정의 누락 시 무시
+import markedKatex from 'marked-katex-extension';
+// @ts-ignore — 타입 정의 누락 시 무시
+import { gfmHeadingId } from 'marked-gfm-heading-id';
+import 'katex/dist/katex.min.css';
+
+function escAttr(s: string): string {
+  return s.replace(/&/g, '&amp;').replace(/"/g, '&quot;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
+}
+function escText(s: string): string {
+  return s.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
+}
+
+const docMarked = new Marked();
+docMarked.use({ mangle: false } as any);
+docMarked.use(gfmHeadingId({ prefix: 'doc-' }));
+docMarked.use(
+  markedKatex({
+    throwOnError: false,
+    nonStandard: false,
+    output: 'html',
+  } as any),
+);
+
+// 이미지 → figure + figcaption (alt 가 있으면). 모든 img 에 data-md-img="1" 마킹.
+docMarked.use({
+  renderer: {
+    image(token: any): string {
+      const href = (token?.href ?? '') as string;
+      const text = (token?.text ?? '') as string;
+      const title = (token?.title ?? '') as string;
+      const titleAttr = title ? ` title="${escAttr(title)}"` : '';
+      const img = `<img src="${escAttr(href)}" alt="${escAttr(text)}"${titleAttr} loading="lazy" data-md-img="1" />`;
+      if (text) {
+        return `<figure class="md-figure">${img}<figcaption>${escText(text)}</figcaption></figure>`;
+      }
+      return img;
+    },
+  },
+});
+
+const SANITIZE_OPTS = {
+  USE_PROFILES: { html: true },
+  // KaTeX (style + aria-hidden), heading anchor (id), 이미지 마킹 (data-md-img), figure caption (figure/figcaption)
+  ADD_ATTR: ['style', 'aria-hidden', 'id', 'data-md-img', 'loading'],
+  ADD_TAGS: ['figure', 'figcaption'],
+  FORBID_TAGS: ['script', 'iframe', 'object', 'embed', 'link', 'meta'],
+  FORBID_ATTR: ['onerror', 'onclick', 'onload', 'onmouseover', 'onfocus'],
+  ALLOW_UNKNOWN_PROTOCOLS: false,
+} as const;
+
+export function renderDocMarkdown(text: string | null | undefined): string {
+  if (!text) return '';
+  try {
+    const html = docMarked.parse(text) as string;
+    return DOMPurify.sanitize(html, SANITIZE_OPTS);
+  } catch {
+    // 마지막 안전망: 모든 태그 제거 후 escape
+    return DOMPurify.sanitize(text, { ALLOWED_TAGS: [], ALLOWED_ATTR: [] });
+  }
+}
diff --git a/frontend/src/routes/documents/[id]/+page.svelte b/frontend/src/routes/documents/[id]/+page.svelte
index bcb8a69..985d852 100644
--- a/frontend/src/routes/documents/[id]/+page.svelte
+++ b/frontend/src/routes/documents/[id]/+page.svelte
@@ -15,6 +15,7 @@
   import EmptyState from '$lib/components/ui/EmptyState.svelte';
   import Skeleton from '$lib/components/ui/Skeleton.svelte';
   import HandwriteCanvas from '$lib/components/HandwriteCanvas.svelte';
+  import MarkdownDoc from '$lib/components/MarkdownDoc.svelte';
   import NoteEditor from '$lib/components/editors/NoteEditor.svelte';
   import EditUrlEditor from '$lib/components/editors/EditUrlEditor.svelte';
   import TagsEditor from '$lib/components/editors/TagsEditor.svelte';
@@ -224,9 +225,14 @@
         <!-- 뷰어 — 모바일 가독성: 본문 폰트 키우고 line-height 늘림 -->
         <Card class="min-h-[500px]">
           {#if viewerType === 'markdown' || viewerType === 'hwp-markdown'}
-            <div class="prose prose-invert prose-base lg:prose-sm max-w-none markdown-body leading-relaxed">
-              {@html renderMd(doc.extracted_text || rawMarkdown || '*텍스트 추출 대기 중*')}
-            </div>
+            <MarkdownDoc
+              mdContent={doc.md_content}
+              mdFrontmatter={doc.md_frontmatter}
+              mdStatus={doc.md_status}
+              mdExtractionError={doc.md_extraction_error}
+              extractedText={doc.extracted_text || rawMarkdown}
+              class="prose prose-invert prose-base lg:prose-sm max-w-none"
+            />
           {:else if viewerType === 'pdf'}
             <iframe
               src="/api/documents/{doc.id}/file?token={getAccessToken()}"
@@ -268,10 +274,15 @@
                   })}
                 </span>
               </div>
-              {#if doc.extracted_text}
-                <div class="markdown-body mb-6">
-                  {@html renderMd(doc.extracted_text)}
-                </div>
+              {#if doc.md_content || doc.extracted_text}
+                <MarkdownDoc
+                  mdContent={doc.md_content}
+                  mdFrontmatter={doc.md_frontmatter}
+                  mdStatus={doc.md_status}
+                  mdExtractionError={doc.md_extraction_error}
+                  extractedText={doc.extracted_text}
+                  class="mb-6"
+                />
               {/if}
               {#if doc.edit_url}
                 <Button