diff --git a/apps/viewer/src/__tests__/ad-carousel.spec.ts b/apps/viewer/src/__tests__/ad-carousel.spec.ts
index 24596f5..88f6919 100644
--- a/apps/viewer/src/__tests__/ad-carousel.spec.ts
+++ b/apps/viewer/src/__tests__/ad-carousel.spec.ts
@@ -38,7 +38,8 @@ function currentSrc(wrapper: VueWrapper): string | null {
 
 /** 图加载失败（含现签 URL 过期）→ emit imageError(adId)（2026-09-29 裂图自愈）。 */
 function triggerImgError(wrapper: VueWrapper): void {
-  wrapper.find('.ad-slide img').trigger('error');
+  // 触发活跃帧的图错误（头/尾克隆帧常驻轨道，首个 .ad-slide 是头克隆）。
+  wrapper.find('.ad-slide.active img').trigger('error');
 }
 
 describe('AdCarousel', () => {
@@ -81,7 +82,7 @@ describe('AdCarousel', () => {
 
   it('opens the current ad link in a new tab via window.open', async () => {
     const wrapper = mountCarousel();
-    await wrapper.get('.ad-slide').trigger('click');
+    await wrapper.get('.ad-slide.active').trigger('click');
     expect(openSpy).toHaveBeenCalledWith('https://link.test/a', '_blank', 'noopener,noreferrer');
   });
 
@@ -128,4 +129,19 @@ describe('AdCarousel', () => {
     expect(emitted).toHaveLength(1);
     expect(emitted![0]).toEqual(['a']); // 当前帧（index 0）的 adId
   });
+
+  it('wraps last→first as one natural leftward slide then a silent snap', async () => {
+    const wrapper = mountCarousel(ADS);
+    await vi.advanceTimersByTimeAsync(8000); // a→b→c（真实末帧）
+    expect(currentSrc(wrapper)).toBe('https://ad.test/c.jpg');
+    expect(wrapper.find('.ad-slides').attributes('style')).toContain('translateX(-300%)');
+    await vi.advanceTimersByTimeAsync(4000); // 环回：a 经尾克隆右→左滑入
+    expect(currentSrc(wrapper)).toBe('https://ad.test/a.jpg'); // 活跃真实帧已回 a
+    let track = wrapper.find('.ad-slides');
+    expect(track.attributes('style')).toContain('translateX(-400%)'); // 视觉在尾克隆位
+    expect(track.classes()).not.toContain('no-transition');
+    await vi.advanceTimersByTimeAsync(600); // 过渡结束 → 关过渡瞬时回位
+    track = wrapper.find('.ad-slides');
+    expect(track.attributes('style')).toContain('translateX(-100%)'); // 等视觉真实首帧
+  });
 });
diff --git a/apps/viewer/src/components/ads/AdCarousel.vue b/apps/viewer/src/components/ads/AdCarousel.vue
index c6c7826..d1cb670 100644
--- a/apps/viewer/src/components/ads/AdCarousel.vue
+++ b/apps/viewer/src/components/ads/AdCarousel.vue
@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { onBeforeUnmount, onMounted, ref, watch } from 'vue';
+import { computed, nextTick, onBeforeUnmount, onMounted, ref, watch } from 'vue';
 import { useI18n } from 'vue-i18n';
 import type { PublicAd } from '../../api/client';
 import { nextIndex, swipeStep } from '../../ads/carousel';
@@ -25,6 +25,65 @@ const current = ref(0);
 /** 指针悬停/按住期间暂停（恢复时重开完整 4s 窗口，非冻结剩余时长）。 */
 const paused = ref(false);
 
+// —— 无缝环回（2026-09-29 用户反馈：末帧→首帧也要右→左自然滑入）——
+// 轨道 = [末帧克隆, 真实帧…, 首帧克隆]（仅多条时）。正进步进到尾克隆 /
+// 后退步进到头克隆都获得单帧宽的自然滑动；过渡结束（定时器兜底）后关过渡、
+// 瞬时跳回等视觉位的真实帧，再恢复过渡——观感连续无回卷。
+const SLIDE_MS = 450;
+/** 轨道渲染位：真实 index + 1（头克隆占位 0）；克隆位 0 与 n+1 仅在环回瞬间。 */
+const trackPos = ref(1);
+/** 瞬时回位期间关闭过渡（transform 跳转不产生动画）。 */
+const noTransition = ref(false);
+let snapTimer: ReturnType<typeof setTimeout> | undefined;
+
+/** 轨道帧序列：{ ad, real }——real 为真实 index，克隆帧为 null。 */
+const trackSlides = computed(() => {
+  const n = props.ads.length;
+  if (n <= 1) return props.ads.map((ad) => ({ ad, real: 0 }));
+  return [
+    { ad: props.ads[n - 1]!, real: null },
+    ...props.ads.map((ad, real) => ({ ad, real })),
+    { ad: props.ads[0]!, real: null },
+  ];
+});
+
+function clearSnapTimer(): void {
+  if (snapTimer !== undefined) {
+    clearTimeout(snapTimer);
+    snapTimer = undefined;
+  }
+}
+
+async function snapBack(): Promise<void> {
+  noTransition.value = true;
+  trackPos.value = current.value + 1;
+  // 同帧应用「关过渡 + 新 transform」，下一拍恢复过渡（transform 已就位不触发）。
+  await nextTick();
+  noTransition.value = false;
+}
+
+/** 移动到真实 index（圆点/滑动/自动轮播共用）：环回走克隆位 + 到位后回跳。 */
+function moveTo(index: number): void {
+  clearSnapTimer();
+  const n = props.ads.length;
+  const from = current.value;
+  let pos = index + 1;
+  if (n > 1) {
+    if (from === n - 1 && index === 0) pos = n + 1; // 末→首：走尾克隆（右→左滑入）
+    else if (from === 0 && index === n - 1) pos = 0; // 首→末：走头克隆（右滑入）
+  }
+  current.value = index;
+  trackPos.value = pos;
+  if (pos === 0 || pos === n + 1) {
+    // 过渡时长 + 缓冲后瞬时回位；期间用户再操作会经 clearSnapTimer 作废。
+    snapTimer = setTimeout(() => {
+      snapTimer = undefined;
+      void snapBack();
+    }, SLIDE_MS + 60);
+  }
+  syncRotation();
+}
+
 let rotateTimer: ReturnType<typeof setInterval> | undefined;
 
 function stopRotation(): void {
@@ -39,31 +98,39 @@ function syncRotation(): void {
   stopRotation();
   if (props.ads.length <= 1 || paused.value) return;
   rotateTimer = setInterval(() => {
-    current.value = nextIndex(props.ads.length, current.value);
+    moveTo(nextIndex(props.ads.length, current.value));
   }, ROTATE_MS);
 }
 
 /** 跳页（圆点/滑动共用）：就位后重开完整 4s 窗口。 */
 function goTo(index: number): void {
-  current.value = index;
-  syncRotation();
+  moveTo(index);
 }
 
 function stepBy(step: 1 | -1): void {
-  goTo(nextIndex(props.ads.length, current.value, step));
+  moveTo(nextIndex(props.ads.length, current.value, step));
 }
 
 /** 新广告列表（token/locale 重载整表替换）→ 回首项并重对齐轮播。 */
 watch(
   () => props.ads,
   () => {
+    clearSnapTimer();
+    noTransition.value = false;
     current.value = 0;
+    trackPos.value = props.ads.length > 1 ? 1 : 0;
     syncRotation();
   },
 );
 watch(paused, syncRotation);
-onMounted(syncRotation);
-onBeforeUnmount(stopRotation);
+onMounted(() => {
+  trackPos.value = props.ads.length > 1 ? 1 : 0;
+  syncRotation();
+});
+onBeforeUnmount(() => {
+  stopRotation();
+  clearSnapTimer();
+});
 
 let touchStart: { x: number; y: number } | null = null;
 
@@ -99,22 +166,28 @@ function openAd(ad: PublicAd): void {
     @touchstart="onTouchStart" @touchend="onTouchEnd"
   >
     <!-- 轨道式滑动（2026-09-29 用户定稿：从右往左滑入，不做淡入淡出）：全帧
-         常驻轨道预加载（首轮切换不空白），track 整体 translateX；仅活跃帧
-         可聚焦；错误上报只看活跃帧。 -->
-    <div class="ad-slides" :style="{ transform: `translateX(-${current * 100}%)` }">
+         常驻轨道预加载（首轮切换不空白），track 整体 translateX；首尾克隆帧
+         令环回也是单帧宽自然滑入（到位后关过渡瞬时回位，见 script）；仅活跃
+         真实帧可聚焦；错误上报只看活跃帧。 -->
+    <div
+      class="ad-slides" :class="{ 'no-transition': noTransition }"
+      :style="{ transform: `translateX(-${trackPos * 100}%)` }"
+    >
       <button
-        v-for="(ad, i) in ads" :key="ad.adId" type="button" class="ad-slide"
-        :class="{ active: i === current }" :aria-label="t('ads.open')"
-        :aria-hidden="i === current ? undefined : 'true'"
-        :tabindex="i === current ? 0 : -1"
-        @click="openAd(ad)"
+        v-for="(slide, i) in trackSlides" :key="`${slide.real ?? 'clone'}-${slide.ad.adId}-${i}`"
+        type="button" class="ad-slide"
+        :class="{ active: slide.real !== null && slide.real === current }"
+        :aria-label="t('ads.open')"
+        :aria-hidden="slide.real !== null && slide.real === current ? undefined : 'true'"
+        :tabindex="slide.real !== null && slide.real === current ? 0 : -1"
+        @click="openAd(slide.ad)"
       >
         <img
-          :src="ad.imageUrl"
+          :src="slide.ad.imageUrl"
           :alt="t('ads.label')"
           decoding="async"
           draggable="false"
-          @error="i === current && emit('imageError', ad.adId)"
+          @error="slide.real !== null && slide.real === current && emit('imageError', slide.ad.adId)"
         >
       </button>
     </div>
@@ -153,6 +226,10 @@ function openAd(ad: PublicAd): void {
   /* 从右往左滑动切换（下一帧自右侧滑入；后退/右滑自然反向）。 */
   transition: transform 0.45s ease;
 }
+/* 环回瞬时回位：克隆位→真实位等视觉跳转（无动画）。 */
+.ad-slides.no-transition {
+  transition: none;
+}
 .ad-slide {
   flex: 0 0 100%;
   display: block;