diff --git a/frontend/src/routes/documents/[id]/+page.svelte b/frontend/src/routes/documents/[id]/+page.svelte
index e124be1..8410728 100644
--- a/frontend/src/routes/documents/[id]/+page.svelte
+++ b/frontend/src/routes/documents/[id]/+page.svelte
@@ -77,10 +77,14 @@
   let treeGroupIndex = $derived(treeGroups ? groupKeyByChunkId(treeGroups) : null);
   let treeExpanded = $state({}); // key 없으면 접힘(기본 전부 접힘). Svelte5 deep-proxy 반응형.
   function toggleTreeGroup(key) { treeExpanded[key] = !treeExpanded[key]; }
+  // sections 로딩 완료 플래그 — 미완 동안 fallback 풀-문서 뷰어를 띄우면, 곧 절뷰로 교체되며
+  // 풀-문서 이미지가 '살짝 보였다 사라지는' 플래시가 난다(절 보유 문서). 로딩 중엔 skeleton.
+  let sectionsLoaded = $state(false);
   async function loadSections() {
     const reqId = docId;
     try { const r = await api(`/documents/${reqId}/sections`); if (reqId === docId) sections = r?.sections ?? []; }
     catch { if (reqId === docId) sections = []; }
+    finally { if (reqId === docId) sectionsLoaded = true; }
   }
 
   onMount(async () => {
@@ -149,7 +153,9 @@
     const gk = idx.get(sel);
     if (gk) untrack(() => { treeExpanded[gk] = true; });
   });
-  let selectedItem = $derived(outline.find((it) => it.section.chunk_id === selectedSectionId) ?? outline[0] ?? null);
+  // selectedSectionId 미설정(초기) 시 defaultSelId(첫 본문 Part)로 바로 해석 — outline[0](표지/front-matter)
+  // 를 잠깐 렌더했다 effect 가 defaultSelId 로 바꾸는 절뷰 내부 플래시 차단.
+  let selectedItem = $derived(outline.find((it) => it.section.chunk_id === (selectedSectionId ?? defaultSelId)) ?? outline[0] ?? null);
   let selectedSection = $derived(selectedItem?.section ?? null);
   let selIdx = $derived(outline.findIndex((it) => it.section.chunk_id === selectedItem?.section?.chunk_id));
   // 절 본문 = 청크 원문(it.bodyText, window 조각 합본) 직접 렌더. 과거 char_start 로 md_content 를
@@ -435,7 +441,10 @@
       </div>
     </div>
 
-    {#if useSectionView}
+    {#if !sectionsLoaded}
+      <!-- sections 로딩 중: fallback 풀-문서(이미지)→절뷰 교체 플래시 방지용 skeleton -->
+      <Skeleton h="h-96" rounded="card" />
+    {:else if useSectionView}
       <!-- 데스크탑(xl+): 3영역 -->
       <div class="hidden xl:grid" style="grid-template-columns:252px minmax(0,1fr) 336px;gap:13px;align-items:start;">
         <div style="background:#f4f7f1;border:1px solid #dde3d6;border-radius:14px;padding:13px 11px;position:sticky;top:14px;max-height:calc(100vh - 2rem);overflow-y:auto;">{@render treeNav(false)}</div>