diff --git a/apps/viewer/e2e/helpers.ts b/apps/viewer/e2e/helpers.ts
index d27d71e..61c6236 100644
--- a/apps/viewer/e2e/helpers.ts
+++ b/apps/viewer/e2e/helpers.ts
@@ -198,6 +198,13 @@ export async function seedPhoto(
   return photoId;
 }
 
+/** 直删照片域行（Task 8 e2e：模拟已分享深链的照片下线——变体行在前、主行在后；
+ * MinIO 对象随 dev 前缀清理约定，不在此删）。 */
+export async function deleteSeededPhoto(photoId: string): Promise<void> {
+  await prisma.photo_variants.deleteMany({ where: { photoId } });
+  await prisma.photos.deleteMany({ where: { id: photoId } });
+}
+
 /** 清理本文件种下的相册域行（扁平字符串外键、无 DB 级联——按子表在前手工删；
  * category_translations 只挂 categoryId，先取分类 id 再删翻译；Task 7 起照片域
  * 同理：先按相册取照片 id 删变体行，再删 photos 主行）。
diff --git a/apps/viewer/e2e/viewer.spec.ts b/apps/viewer/e2e/viewer.spec.ts
new file mode 100644
index 0000000..9bc8023
--- /dev/null
+++ b/apps/viewer/e2e/viewer.spec.ts
@@ -0,0 +1,172 @@
+import { expect, test, type Page } from '@playwright/test';
+import { cleanupSeededAlbums, deleteSeededPhoto, seedAlbum, seedPhoto } from './helpers';
+
+// Task 8 大图查看器 Playwright（真实后端）：点击开大图（browse 经签名 URL 取回
+// 真实字节）→ 左右切换保持列表序列 → 滚轮缩放（受控 transform）→ 关闭回原滚动
+// 位置 → 深链直达（单图先行 + 背后列表构成序列）→ 404 深链本地化提示 → 越过
+// 末页边界的导航扩展序列。
+
+test.afterAll(async () => {
+  await cleanupSeededAlbums();
+});
+
+const RATIOS: Array<{ width: number; height: number }> = [
+  { width: 480, height: 300 },
+  { width: 300, height: 480 },
+  { width: 400, height: 400 },
+  { width: 360, height: 480 },
+  { width: 480, height: 270 },
+];
+
+/** 种「查看器相册」：count 张已发布照片，publishedAt 逐张递减 60s（列表顺序确定）。
+ * 返回 token 与按列表顺序排列的 photoId。 */
+async function seedViewerAlbum(alias: string, count: number): Promise<{ token: string; photoIds: string[] }> {
+  const album = await seedAlbum({
+    alias,
+    translations: [{ locale: 'zh-CN', title: '大图查看测试相册' }],
+  });
+  const photoIds: string[] = [];
+  const base = Date.now();
+  for (let i = 0; i < count; i++) {
+    const ratio = RATIOS[i % RATIOS.length]!;
+    photoIds.push(
+      await seedPhoto(album.id, `${alias}-p${i}`, {
+        width: ratio.width,
+        height: ratio.height,
+        publishedAt: new Date(base - (i + 1) * 60_000),
+      }),
+    );
+  }
+  return { token: album.publicToken, photoIds };
+}
+
+async function openLocale(page: Page, token: string, path = ''): Promise<void> {
+  await page.addInitScript(() => localStorage.setItem('viewer.locale', 'zh-CN'));
+  await page.goto(`/a/${token}${path}`);
+}
+
+/** 大图 <img> 的自然尺寸（签名 URL 取回真实字节则 > 0）。 */
+async function browseNaturalWidth(page: Page): Promise<number> {
+  return page.locator('img.photo').evaluate((img) => (img as HTMLImageElement).naturalWidth);
+}
+
+test('open from feed, navigate in sequence, zoom, close restores scroll and url', async ({ page }) => {
+  test.setTimeout(90_000);
+  const { token, photoIds } = await seedViewerAlbum('viewer-open', 8);
+  await openLocale(page, token);
+
+  await expect(page.locator('.cell')).toHaveCount(8);
+  await page.evaluate(() => window.scrollTo(0, 600));
+  await page.waitForTimeout(100); // 等 scrollEnd 后的懒加载稳定
+
+  // 点击第 3 格 → 大图：browse 图取回真实字节，URL 换为深链。
+  await page.locator('.cell').nth(2).click();
+  await expect(page.locator('.lightbox')).toBeVisible();
+  await expect
+    .poll(() => browseNaturalWidth(page))
+    .toBeGreaterThan(0);
+  await expect(page.locator('img.photo')).toHaveAttribute('src', new RegExp(photoIds[2]!));
+  expect(page.url()).toContain(`/a/${token}/p/${photoIds[2]}`);
+
+  // 记录开图后的滚动位置（关闭需精确回位）。
+  const scrollBefore = await page.evaluate(() => window.scrollY);
+  expect(scrollBefore).toBeGreaterThan(0);
+
+  // 右切 ×3：第 4/5/6 张依次换 src，URL 同步 replace。
+  for (const step of [3, 4, 5]) {
+    await page.keyboard.press('ArrowRight');
+    await expect(page.locator('img.photo')).toHaveAttribute('src', new RegExp(photoIds[step]!), { timeout: 10_000 });
+  }
+  expect(page.url()).toContain(`/a/${token}/p/${photoIds[5]}`);
+  await expect(page.locator('.counter')).toHaveText('6 / 8');
+
+  // 滚轮缩放（无需 ctrl）：transform scale > 1；双击复位。
+  const box = await page.locator('.lightbox').boundingBox();
+  expect(box).not.toBeNull();
+  await page.mouse.move(box!.x + box!.width / 2, box!.y + box!.height / 2);
+  await page.mouse.wheel(0, -360);
+  await page.mouse.wheel(0, -360);
+  const zoomedScale = await page.locator('img.photo').evaluate((img) => {
+    const matrix = new DOMMatrixReadOnly(getComputedStyle(img).transform);
+    return matrix.a;
+  });
+  expect(zoomedScale).toBeGreaterThan(1.2);
+  await page.locator('img.photo').dblclick();
+  await expect
+    .poll(async () =>
+      page.locator('img.photo').evaluate((img) => new DOMMatrixReadOnly(getComputedStyle(img).transform).a),
+    )
+    .toBeCloseTo(1, 1);
+
+  // 关闭：URL 弹回相册路由，滚动精确回位。
+  await page.locator('.control.close').click();
+  await expect(page.locator('.lightbox')).toHaveCount(0);
+  await expect(page).toHaveURL(new RegExp(`/a/${token}/?$`));
+  await expect
+    .poll(() => page.evaluate(() => window.scrollY))
+    .toBe(scrollBefore);
+});
+
+test('deep link opens on the target photo with the list loaded behind', async ({ page }) => {
+  test.setTimeout(90_000);
+  const { token, photoIds } = await seedViewerAlbum('viewer-deep', 8);
+  const target = photoIds[4]!; // 第 5 张
+  await openLocale(page, token, `/p/${target}`);
+
+  await expect(page.locator('.lightbox')).toBeVisible();
+  await expect
+    .poll(() => browseNaturalWidth(page))
+    .toBeGreaterThan(0);
+  await expect(page.locator('img.photo')).toHaveAttribute('src', new RegExp(target));
+  await expect(page.locator('.counter')).toHaveText('5 / 8');
+  // 背后列表已构成序列（8 张）。
+  await expect(page.locator('.cell')).toHaveCount(8);
+
+  // 序列可切换：左切到第 4 张，URL 同步。
+  await page.keyboard.press('ArrowLeft');
+  await expect(page.locator('img.photo')).toHaveAttribute('src', new RegExp(photoIds[3]!), { timeout: 10_000 });
+  expect(page.url()).toContain(`/a/${token}/p/${photoIds[3]}`);
+
+  // 关闭 → 回相册路由（深链直达无本会话 push：replace 语义）。
+  await page.locator('.control.close').click();
+  await expect(page.locator('.lightbox')).toHaveCount(0);
+  await expect(page).toHaveURL(new RegExp(`/a/${token}/?$`));
+});
+
+test('deep link to a removed photo shows the localized notice and a working back link', async ({ page }) => {
+  test.setTimeout(90_000);
+  const { token, photoIds } = await seedViewerAlbum('viewer-404', 2);
+  const gone = photoIds[1]!;
+  await deleteSeededPhoto(gone); // 模拟照片已下线（旧分享链接）
+
+  await openLocale(page, token, `/p/${gone}`);
+  const notice = page.locator('.deep-link-notice');
+  await expect(notice).toBeVisible();
+  await expect(notice).toContainText('照片不存在或已下线');
+  await expect(page.locator('.lightbox')).toHaveCount(0);
+
+  const back = notice.getByRole('link', { name: '返回相册' });
+  await back.click();
+  await expect(page).toHaveURL(new RegExp(`/a/${token}/?$`));
+  await expect(page.locator('.deep-link-notice')).toHaveCount(0);
+  await expect(page.getByRole('heading', { name: '大图查看测试相册' })).toBeVisible();
+});
+
+test('navigating past the first page extends the sequence', async ({ page }) => {
+  test.setTimeout(120_000);
+  // 32 张：公开列表默认页 30 → 第 31/32 张需导航越过末尾时拉第 2 页。
+  const { token, photoIds } = await seedViewerAlbum('viewer-extend', 32);
+  await openLocale(page, token);
+
+  await expect(page.locator('.cell')).toHaveCount(30);
+  await page.locator('.cell').nth(29).click(); // 第 1 页最后一张
+  await expect(page.locator('.lightbox')).toBeVisible();
+
+  // 打开即临近末页边界：相邻预取已后台拉取第 2 页（设计行为），右切越过末尾
+  // 落在第 31 张（序列第 2 页），列表同步扩展。
+  await page.keyboard.press('ArrowRight');
+  await expect(page.locator('img.photo')).toHaveAttribute('src', new RegExp(photoIds[30]!), { timeout: 15_000 });
+  await expect(page.locator('.counter')).toHaveText('31 / 32');
+  // 背后列表同步扩展到 32 张。
+  await expect(page.locator('.cell')).toHaveCount(32);
+});
diff --git a/apps/viewer/src/__tests__/feed.spec.ts b/apps/viewer/src/__tests__/feed.spec.ts
index 1f9a8b0..8b647b5 100644
--- a/apps/viewer/src/__tests__/feed.spec.ts
+++ b/apps/viewer/src/__tests__/feed.spec.ts
@@ -1,4 +1,5 @@
 import { flushPromises, mount, type VueWrapper } from '@vue/test-utils';
+import { computed, defineComponent } from 'vue';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import {
   ApiError,
@@ -9,10 +10,13 @@ import {
 } from '../api/client';
 import { createViewerI18n, type ViewerI18n } from '../i18n';
 import PhotoFeed from '../components/PhotoFeed.vue';
+import { usePhotoSequence, type PhotoSequence } from '../feed/sequence';
 
-// PhotoFeed（Task 7）组件测试：api client 以真实模块为底、替身 getPublicPhotos /
-// getPublicPhoto；IntersectionObserver / ResizeObserver 以可控假件替换（jsdom 无实现），
-// clientWidth 以原型 getter mock（jsdom 恒 0）。布局纯函数已在 feed-layout.spec 覆盖。
+// PhotoFeed（Task 7；Task 8 起数据层在 PhotoSequence）组件测试：api client 以真实
+// 模块为底、替身 getPublicPhotos / getPublicPhoto；IntersectionObserver /
+// ResizeObserver 以可控假件替换（jsdom 无实现），clientWidth 以原型 getter mock
+// （jsdom 恒 0）。序列数据/轮询已在 sequence.spec.ts 覆盖；布局纯函数在
+// feed-layout.spec。宿主组件持 sequence（对齐 ActivityPage 的真实组装方式）。
 
 vi.mock('../api/client', async (importOriginal) => {
   const actual = await importOriginal<typeof import('../api/client')>();
@@ -109,20 +113,32 @@ function makeList(items: PublicPhoto[], nextCursor: string | null = null): Publi
 let i18n: ViewerI18n;
 const mounted: VueWrapper[] = [];
 
-function mountFeed(props: { token?: string; locale?: string; category?: string | null } = {}): VueWrapper {
-  const wrapper = mount(PhotoFeed, {
-    global: { plugins: [i18n] },
-    props: {
-      token: props.token ?? 'tok-feed',
-      locale: props.locale ?? 'zh-CN',
-      category: props.category ?? null,
+/** 宿主：创建 sequence 并渲染 PhotoFeed（镜像 ActivityPage 组装）；捕获 open 事件。 */
+function mountFeed(props: { token?: string; locale?: string; category?: string | null } = {}): {
+  wrapper: VueWrapper;
+  sequence: PhotoSequence;
+  opened: string[];
+} {
+  const opened: string[] = [];
+  const Host = defineComponent({
+    components: { PhotoFeed },
+    setup() {
+      const sequence = usePhotoSequence({
+        token: computed(() => props.token ?? 'tok-feed'),
+        locale: computed(() => props.locale ?? 'zh-CN'),
+        category: computed(() => props.category ?? null),
+      });
+      return { sequence, onOpen: (photoId: string) => opened.push(photoId) };
     },
+    template: `<PhotoFeed :sequence="sequence" @open="onOpen" />`,
   });
+  const wrapper = mount(Host, { global: { plugins: [i18n] } });
   mounted.push(wrapper);
-  return wrapper;
+  const sequence = (wrapper.vm as unknown as { sequence: PhotoSequence }).sequence;
+  return { wrapper, sequence, opened };
 }
 
-describe('photo feed (Task 7)', () => {
+describe('photo feed (Task 7 / Task 8 sequence props)', () => {
   beforeEach(() => {
     localStorage.clear();
     i18n = createViewerI18n('zh-CN');
@@ -144,11 +160,10 @@ describe('photo feed (Task 7)', () => {
     }
     vi.unstubAllGlobals();
     vi.restoreAllMocks();
-    vi.useRealTimers();
   });
 
   it('renders first page as absolute-positioned cells with reserved heights', async () => {
-    const wrapper = mountFeed();
+    const { wrapper } = mountFeed();
     await flushPromises();
 
     expect(mockedGetPublicPhotos).toHaveBeenCalledWith('tok-feed', { locale: 'zh-CN' });
@@ -161,8 +176,16 @@ describe('photo feed (Task 7)', () => {
     expect(cells[2].attributes('style')).toContain('top: 224px');
   });
 
+  it('emits open with the photoId when a cell is clicked', async () => {
+    const { wrapper, opened } = mountFeed();
+    await flushPromises();
+
+    await wrapper.findAll('.cell')[1].trigger('click');
+    expect(opened).toEqual(['p2']);
+  });
+
   it('binds img src only after the cell approaches the viewport (lazy swap)', async () => {
-    const wrapper = mountFeed();
+    const { wrapper } = mountFeed();
     await flushPromises();
 
     expect(wrapper.findAll('img.cell-img')).toHaveLength(0);
@@ -177,7 +200,7 @@ describe('photo feed (Task 7)', () => {
   });
 
   it('loads the next page when the sentinel intersects, dedupes and stops at exhaustion', async () => {
-    const wrapper = mountFeed();
+    const { wrapper } = mountFeed();
     await flushPromises();
 
     const sentinel = wrapper.find('.sentinel');
@@ -199,59 +222,9 @@ describe('photo feed (Task 7)', () => {
     expect(wrapper.find('.new-photo-bar').exists()).toBe(false);
   });
 
-  it('does not fire a second page fetch while one is in flight', async () => {
-    const wrapper = mountFeed();
-    await flushPromises();
-    mockedGetPublicPhotos.mockClear();
-
-    let resolvePage!: (value: PublicPhotoList) => void;
-    mockedGetPublicPhotos.mockReturnValueOnce(
-      new Promise<PublicPhotoList>((resolve) => {
-        resolvePage = resolve;
-      }),
-    );
-    const sentinel = wrapper.find('.sentinel');
-    sentinelObserver().trigger([sentinel.element], true);
-    sentinelObserver().trigger([sentinel.element], true);
-    await flushPromises();
-    expect(mockedGetPublicPhotos).toHaveBeenCalledTimes(1);
-
-    resolvePage(makeList([makePhoto('p4')], null));
-    await flushPromises();
-    expect(wrapper.findAll('.cell')).toHaveLength(4);
-  });
-
-  it('switching category resets the list and passes the filter through', async () => {
-    const wrapper = mountFeed();
-    await flushPromises();
-    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('c1p1'), makePhoto('c1p2')], null));
-
-    await wrapper.setProps({ category: 'cat-1' });
-    await flushPromises();
-
-    expect(mockedGetPublicPhotos).toHaveBeenLastCalledWith(
-      'tok-feed',
-      expect.objectContaining({ category: 'cat-1', locale: 'zh-CN' }),
-    );
-    expect(wrapper.findAll('.cell')).toHaveLength(2);
-  });
-
-  it('locale switch re-fetches the current category (filter preserved)', async () => {
-    const wrapper = mountFeed({ category: 'cat-1' });
-    await flushPromises();
-
-    await wrapper.setProps({ locale: 'en' });
-    await flushPromises();
-
-    expect(mockedGetPublicPhotos).toHaveBeenLastCalledWith(
-      'tok-feed',
-      expect.objectContaining({ locale: 'en', category: 'cat-1' }),
-    );
-  });
-
   it('renders the localized empty state when the album has no photos', async () => {
     mockedGetPublicPhotos.mockResolvedValueOnce(makeList([]));
-    const wrapper = mountFeed();
+    const { wrapper } = mountFeed();
     await flushPromises();
 
     expect(wrapper.find('.empty-notice').text()).toBe('照片即将上线');
@@ -262,7 +235,7 @@ describe('photo feed (Task 7)', () => {
     mockedGetPublicPhotos
       .mockRejectedValueOnce(new ApiError('NETWORK_ERROR', 'network down', 0, null))
       .mockResolvedValueOnce(makeList([makePhoto('p1')], null));
-    const wrapper = mountFeed();
+    const { wrapper } = mountFeed();
     await flushPromises();
 
     expect(wrapper.find('.error[role="alert"]').text()).toContain('网络连接失败');
@@ -274,7 +247,7 @@ describe('photo feed (Task 7)', () => {
   });
 
   it('retries a failed thumb once with a refreshed signed URL, then hides the img', async () => {
-    const wrapper = mountFeed();
+    const { wrapper } = mountFeed();
     await flushPromises();
     lazyObserver().trigger(wrapper.findAll('.cell').map((cell) => cell.element), true);
     await vi.waitFor(() => expect(wrapper.findAll('img.cell-img')).toHaveLength(3));
@@ -298,83 +271,3 @@ describe('photo feed (Task 7)', () => {
     expect(mockedGetPublicPhoto).toHaveBeenCalledTimes(1);
   });
 });
-
-describe('photo feed polling (Task 7)', () => {
-  beforeEach(() => {
-    localStorage.clear();
-    i18n = createViewerI18n('zh-CN');
-    FakeIntersectionObserver.instances = [];
-    vi.stubGlobal('IntersectionObserver', FakeIntersectionObserver);
-    vi.stubGlobal('ResizeObserver', FakeResizeObserver);
-    const proto = Object.prototype.hasOwnProperty.call(HTMLElement.prototype, 'clientWidth')
-      ? HTMLElement.prototype
-      : Element.prototype;
-    vi.spyOn(proto, 'clientWidth', 'get').mockReturnValue(700);
-    mockedGetPublicPhotos.mockReset().mockResolvedValue(makeList([makePhoto('p1'), makePhoto('p2')], null));
-    mockedGetPublicPhoto.mockReset();
-    vi.useFakeTimers();
-  });
-
-  afterEach(() => {
-    while (mounted.length > 0) {
-      mounted.pop()?.unmount();
-    }
-    vi.unstubAllGlobals();
-    vi.restoreAllMocks();
-    vi.useRealTimers();
-  });
-
-  it('poll detects new photos, shows the hint bar; click refreshes to page 1, clears the hint and scrolls top', async () => {
-    const scrollTo = vi.spyOn(window, 'scrollTo').mockImplementation(() => {});
-    const wrapper = mountFeed();
-    await flushPromises();
-    expect(wrapper.find('.new-photo-bar').exists()).toBe(false);
-
-    // 轮询取到的第 1 页含未知 id p9 → 只亮提示条，不自动插入。
-    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('p9'), makePhoto('p1'), makePhoto('p2')], null));
-    vi.advanceTimersByTime(30_000);
-    await flushPromises();
-    expect(wrapper.find('.new-photo-bar').text()).toBe('有新照片，点击查看');
-    expect(wrapper.findAll('.cell')).toHaveLength(2);
-
-    // 点击提示条：整表刷新（第 1 页含新照片）并回顶。
-    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('p9'), makePhoto('p1'), makePhoto('p2')], null));
-    await wrapper.find('.new-photo-bar').trigger('click');
-    await flushPromises();
-
-    expect(wrapper.findAll('.cell')).toHaveLength(3);
-    expect(wrapper.find('.new-photo-bar').exists()).toBe(false);
-    expect(scrollTo).toHaveBeenCalledWith(0, 0);
-  });
-
-  it('keeps polling silent on failure (no error state, no hint)', async () => {
-    const wrapper = mountFeed();
-    await flushPromises();
-
-    mockedGetPublicPhotos.mockRejectedValueOnce(new ApiError('INTERNAL_ERROR', 'boom', 500, 'req-1'));
-    vi.advanceTimersByTime(30_000);
-    await flushPromises();
-
-    expect(wrapper.find('.error').exists()).toBe(false);
-    expect(wrapper.find('.new-photo-bar').exists()).toBe(false);
-    expect(wrapper.findAll('.cell')).toHaveLength(2);
-  });
-
-  it('pauses polling while the tab is hidden and resumes when visible again', async () => {
-    mountFeed();
-    await flushPromises();
-    mockedGetPublicPhotos.mockClear();
-
-    const hidden = vi.spyOn(document, 'hidden', 'get').mockReturnValue(true);
-    document.dispatchEvent(new Event('visibilitychange'));
-    vi.advanceTimersByTime(120_000);
-    await flushPromises();
-    expect(mockedGetPublicPhotos).not.toHaveBeenCalled();
-
-    hidden.mockReturnValue(false);
-    document.dispatchEvent(new Event('visibilitychange'));
-    vi.advanceTimersByTime(30_000);
-    await flushPromises();
-    expect(mockedGetPublicPhotos).toHaveBeenCalledTimes(1);
-  });
-});
diff --git a/apps/viewer/src/__tests__/lightbox.spec.ts b/apps/viewer/src/__tests__/lightbox.spec.ts
new file mode 100644
index 0000000..5b87d77
--- /dev/null
+++ b/apps/viewer/src/__tests__/lightbox.spec.ts
@@ -0,0 +1,299 @@
+import { flushPromises, mount, type VueWrapper } from '@vue/test-utils';
+import { defineComponent, nextTick, ref } from 'vue';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import {
+  ApiError,
+  getPublicPhoto,
+  getPublicPhotos,
+  type PublicPhoto,
+  type PublicPhotoList,
+} from '../api/client';
+import { createViewerI18n, type ViewerI18n } from '../i18n';
+import PhotoLightbox from '../components/PhotoLightbox.vue';
+import { usePhotoSequence, type PhotoSequence } from '../feed/sequence';
+
+// PhotoLightbox（Task 8）组件测试：browse 渲染/导航/序列扩展、wheel 缩放与双击
+// 复位、Esc/背景/按钮关闭、指针轻扫切换、签名过期静默重取与 404 移除上报。
+// 深链解析与 URL 同步在 viewer-route.spec（真实路由）覆盖。
+
+vi.mock('../api/client', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('../api/client')>();
+  return { ...actual, getPublicPhotos: vi.fn(), getPublicPhoto: vi.fn() };
+});
+
+const mockedGetPublicPhotos = vi.mocked(getPublicPhotos);
+const mockedGetPublicPhoto = vi.mocked(getPublicPhoto);
+
+function makePhoto(id: string, likeCount = 0): PublicPhoto {
+  return {
+    photoId: id,
+    width: 800,
+    height: 500,
+    thumb: { url: `http://img.test/${id}-thumb.jpg?s=1`, expiresAt: '2026-10-01T00:00:00.000Z' },
+    browse: { url: `http://img.test/${id}-browse.jpg?s=1`, expiresAt: '2026-10-01T00:00:00.000Z' },
+    likeCount,
+    publishedAt: '2026-10-01T00:00:00.000Z',
+  };
+}
+
+function makeList(items: PublicPhoto[], nextCursor: string | null = null): PublicPhotoList {
+  return { items, nextCursor, hasMore: nextCursor !== null };
+}
+
+let i18n: ViewerI18n;
+const mounted: VueWrapper[] = [];
+
+/** 宿主：sequence + v-model photoId（镜像 ActivityPage 组装）。页面数据经
+ * mockedGetPublicPhotos 的当前 mock 队列供给（与真实时序一致：挂载后到达）。 */
+function mountLightbox(photoId: string): VueWrapper {
+  const Host = defineComponent({
+    components: { PhotoLightbox },
+    setup() {
+      const sequence = usePhotoSequence({
+        token: ref('tok-lb'),
+        locale: ref('zh-CN'),
+        category: ref(null),
+      });
+      const current = ref(photoId);
+      return { sequence, photoId: current };
+    },
+    template: `<PhotoLightbox v-model:photo-id="photoId" :sequence="sequence" />`,
+  });
+  const wrapper = mount(Host, { global: { plugins: [i18n] } });
+  mounted.push(wrapper);
+  return wrapper;
+}
+
+function lightbox(wrapper: VueWrapper): VueWrapper<Record<string, never>> {
+  return wrapper.getComponent(PhotoLightbox) as unknown as VueWrapper<Record<string, never>>;
+}
+
+function img(wrapper: VueWrapper) {
+  return wrapper.find('img.photo');
+}
+
+/** jsdom 无 PointerEvent 构造器：MouseEvent 补 pointerId/pointerType 字段。 */
+function pointerEvent(
+  type: 'pointerdown' | 'pointermove' | 'pointerup',
+  init: { pointerId?: number; clientX?: number; clientY?: number; pointerType?: string },
+): PointerEvent {
+  const event = new MouseEvent(type, {
+    bubbles: true,
+    cancelable: true,
+    clientX: init.clientX ?? 0,
+    clientY: init.clientY ?? 0,
+  });
+  return Object.assign(event, {
+    pointerId: init.pointerId ?? 1,
+    pointerType: init.pointerType ?? 'touch',
+  }) as unknown as PointerEvent;
+}
+
+function keydown(key: string): void {
+  window.dispatchEvent(new KeyboardEvent('keydown', { key, cancelable: true }));
+}
+
+/** test-utils 的 trigger 无法写 MouseEvent 只读坐标：直接派生 WheelEvent。 */
+function wheel(wrapper: VueWrapper, deltaY: number, clientX = 100, clientY = 80): void {
+  wrapper.find('.lightbox').element.dispatchEvent(
+    new WheelEvent('wheel', { bubbles: true, cancelable: true, deltaY, clientX, clientY }),
+  );
+}
+
+describe('photo lightbox (Task 8)', () => {
+  beforeEach(() => {
+    localStorage.clear();
+    i18n = createViewerI18n('zh-CN');
+    mockedGetPublicPhotos.mockReset().mockResolvedValue(makeList([makePhoto('p1'), makePhoto('p2'), makePhoto('p3')]));
+    mockedGetPublicPhoto.mockReset();
+  });
+
+  afterEach(() => {
+    while (mounted.length > 0) {
+      mounted.pop()?.unmount();
+    }
+    vi.restoreAllMocks();
+  });
+
+  it('renders the current browse url with counter and like count', async () => {
+    mockedGetPublicPhotos.mockResolvedValue(
+      makeList([makePhoto('p1'), makePhoto('p2', 7), makePhoto('p3')]),
+    );
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+
+    expect(img(wrapper).attributes('src')).toBe('http://img.test/p2-browse.jpg?s=1');
+    expect(wrapper.find('.counter').text()).toBe('2 / 3');
+    expect(wrapper.find('.likes').text()).toBe('7 次点赞');
+  });
+
+  it('navigates with buttons and arrow keys, keeping the list order', async () => {
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+
+    await wrapper.find('.nav.next').trigger('click');
+    expect(lightbox(wrapper).emitted('update:photoId')).toEqual([['p3']]);
+
+    keydown('ArrowLeft');
+    await flushPromises();
+    expect(lightbox(wrapper).emitted('update:photoId')).toEqual([['p3'], ['p2']]);
+
+    keydown('ArrowLeft');
+    await flushPromises();
+    expect(lightbox(wrapper).emitted('update:photoId')).toEqual([['p3'], ['p2'], ['p1']]);
+
+    // 首张：previous 按钮禁用，再按左键不再发事件；末张同理（无更多页）。
+    expect(wrapper.find('.nav.prev').attributes('disabled')).toBeDefined();
+    keydown('ArrowLeft');
+    await flushPromises();
+    expect(lightbox(wrapper).emitted('update:photoId')).toHaveLength(3);
+    expect(wrapper.find('.nav.next').attributes('disabled')).toBeUndefined();
+  });
+
+  it('closes on Esc, close button and backdrop click', async () => {
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+
+    keydown('Escape');
+    expect(lightbox(wrapper).emitted('close')).toHaveLength(1);
+
+    await wrapper.find('.control.close').trigger('click');
+    expect(lightbox(wrapper).emitted('close')).toHaveLength(2);
+
+    await wrapper.find('.backdrop').trigger('click');
+    expect(lightbox(wrapper).emitted('close')).toHaveLength(3);
+  });
+
+  it('zooms with wheel around the cursor and clamps to [1, 4]; dblclick resets', async () => {
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+
+    // jsdom 下容器 rect 为 0 → 锚点 = 事件坐标（100, 80）。
+    wheel(wrapper, -240);
+    await nextTick();
+    let style = img(wrapper).attributes('style') ?? '';
+    expect(style).toContain('scale(');
+    const zoomedScale = Number(/scale\(([\d.]+)\)/.exec(style)?.[1]);
+    expect(zoomedScale).toBeGreaterThan(1);
+    // 不动点：锚点屏幕位置不变（translate 补偿）。
+    const zoomedTx = Number(/translate\((-?[\d.]+)px/.exec(style)?.[1]);
+    expect(100 * zoomedScale + zoomedTx).toBeCloseTo(100, 5);
+
+    // 连续放大钳制到 4。
+    for (let i = 0; i < 8; i++) wheel(wrapper, -600);
+    await nextTick();
+    style = img(wrapper).attributes('style') ?? '';
+    expect(Number(/scale\(([\d.]+)\)/.exec(style)?.[1])).toBe(4);
+
+    // 缩到底回到 1 且平移归零（复位对齐）。
+    for (let i = 0; i < 12; i++) wheel(wrapper, 600);
+    await nextTick();
+    style = img(wrapper).attributes('style') ?? '';
+    expect(style).toContain('translate(0px, 0px) scale(1)');
+
+    // 双击复位。
+    wheel(wrapper, -240);
+    await nextTick();
+    await img(wrapper).trigger('dblclick');
+    expect(img(wrapper).attributes('style')).toContain('scale(1)');
+  });
+
+  it('swipe navigates when flat; drag on backdrop does not close', async () => {
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+    const root = wrapper.find('.lightbox');
+
+    // 左滑 80px → 下一张。
+    root.element.dispatchEvent(pointerEvent('pointerdown', { pointerId: 1, clientX: 200, clientY: 150 }));
+    root.element.dispatchEvent(pointerEvent('pointermove', { pointerId: 1, clientX: 150, clientY: 150 }));
+    root.element.dispatchEvent(pointerEvent('pointerup', { pointerId: 1, clientX: 120, clientY: 150 }));
+    await flushPromises();
+    expect(lightbox(wrapper).emitted('update:photoId')).toEqual([['p3']]);
+
+    // 拖拽距离超过阈值后收尾在背景上：click 不关闭。
+    root.element.dispatchEvent(pointerEvent('pointerdown', { pointerId: 1, clientX: 200, clientY: 150 }));
+    root.element.dispatchEvent(pointerEvent('pointermove', { pointerId: 1, clientX: 100, clientY: 160 }));
+    root.element.dispatchEvent(pointerEvent('pointerup', { pointerId: 1, clientX: 100, clientY: 160 }));
+    await wrapper.find('.backdrop').trigger('click');
+    expect(lightbox(wrapper).emitted('close')).toBeUndefined();
+  });
+
+  it('extends the sequence when navigating past the end with more pages', async () => {
+    let resolvePage!: (value: PublicPhotoList) => void;
+    mockedGetPublicPhotos.mockReset();
+    mockedGetPublicPhotos
+      .mockResolvedValueOnce(makeList([makePhoto('p1'), makePhoto('p2'), makePhoto('p3')], 'cur-1'))
+      .mockReturnValueOnce(
+        new Promise<PublicPhotoList>((resolve) => {
+          resolvePage = resolve;
+        }),
+      );
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+
+    // 临近末尾的预取已在途（受控 promise 挂起）→ 右切越过末尾与预取共用同一请求。
+    await wrapper.find('.nav.next').trigger('click'); // → p3（预取仍未完成）
+    expect(lightbox(wrapper).emitted('update:photoId')).toEqual([['p3']]);
+
+    await wrapper.find('.nav.next').trigger('click'); // 越过末尾：等待扩展
+    expect(lightbox(wrapper).emitted('update:photoId')).toEqual([['p3']]); // 未落地前不切换
+    expect(wrapper.find('.loading').exists()).toBe(true);
+
+    resolvePage(makeList([makePhoto('p4')], null));
+    await flushPromises();
+    expect(lightbox(wrapper).emitted('update:photoId')).toEqual([['p3'], ['p4']]);
+    expect(mockedGetPublicPhotos).toHaveBeenCalledTimes(2);
+  });
+
+  it('silently refreshes an expired signed url on img error', async () => {
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+    mockedGetPublicPhoto.mockResolvedValue({
+      ...makePhoto('p2'),
+      categoryId: null,
+      browse: { url: 'http://img.test/p2-browse.jpg?s=2', expiresAt: '2026-10-01T01:00:00.000Z' },
+    });
+
+    await img(wrapper).trigger('error');
+    await flushPromises();
+
+    expect(mockedGetPublicPhoto).toHaveBeenCalledWith('tok-lb', 'p2');
+    expect(img(wrapper).attributes('src')).toBe('http://img.test/p2-browse.jpg?s=2');
+  });
+
+  it('reports removal with the pre-removal index when the photo is gone (404)', async () => {
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+    mockedGetPublicPhoto.mockRejectedValue(new ApiError('PHOTO_NOT_PUBLIC', 'gone', 404, 'req-1'));
+
+    await img(wrapper).trigger('error');
+    await flushPromises();
+
+    expect(lightbox(wrapper).emitted('removed')).toEqual([['p2', 1]]);
+    expect((wrapper.vm as unknown as { sequence: PhotoSequence }).sequence.photos.map((p) => p.photoId)).toEqual(['p1', 'p3']);
+  });
+
+  it('shows a retryable failure notice for non-404 refresh failures', async () => {
+    const wrapper = mountLightbox('p2');
+    await flushPromises();
+    mockedGetPublicPhoto.mockRejectedValue(new ApiError('NETWORK_ERROR', 'down', 0, null));
+
+    await img(wrapper).trigger('error');
+    await flushPromises();
+    expect(wrapper.find('.img-failed[role="alert"]').text()).toContain('图片加载失败');
+
+    // 重试：清标记并强制 <img> 重挂载（key 变化），错误链可再次触发。
+    mockedGetPublicPhoto.mockResolvedValue({
+      ...makePhoto('p2'),
+      categoryId: null,
+      browse: { url: 'http://img.test/p2-browse.jpg?s=3', expiresAt: '2026-10-01T02:00:00.000Z' },
+    });
+    await wrapper.find('.img-failed button').trigger('click');
+    await nextTick();
+    expect(wrapper.find('.img-failed').exists()).toBe(false); // 占位收起，img 回到加载中
+    expect(img(wrapper).exists()).toBe(true);
+    await img(wrapper).trigger('error');
+    await flushPromises();
+    expect(img(wrapper).attributes('src')).toBe('http://img.test/p2-browse.jpg?s=3');
+  });
+});
diff --git a/apps/viewer/src/__tests__/routing.spec.ts b/apps/viewer/src/__tests__/routing.spec.ts
index b62805d..691b92d 100644
--- a/apps/viewer/src/__tests__/routing.spec.ts
+++ b/apps/viewer/src/__tests__/routing.spec.ts
@@ -1,24 +1,27 @@
 import { flushPromises, mount, type VueWrapper } from '@vue/test-utils';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import App from '../App.vue';
-import { getPublicAlbum } from '../api/client';
+import { getPublicAlbum, getPublicPhoto } from '../api/client';
 import { createViewerI18n } from '../i18n';
 import { router } from '../router';
 import { makeAlbum } from './fixtures';
 
 // 路由解析（Task 5 脚手架测试对齐 Task 6 真实活动页）：token/photoId 参数经
-// api mock 断言——活动页以 token 取数，photoId 供 Task 8 深链定位（不影响取数）。
-// getPublicPhotos 一并替身为空页（Task 7 起活动页内嵌 PhotoFeed）。
+// api mock 断言——活动页以 token 取数，photoId 驱动 Task 8 深链（单图先行 + 序列
+// 兜底）。getPublicPhotos / getPublicPhoto 一并替身（Task 7 起活动页内嵌 PhotoFeed，
+// Task 8 起深链取单图）。
 vi.mock('../api/client', async (importOriginal) => {
   const actual = await importOriginal<typeof import('../api/client')>();
   return {
     ...actual,
     getPublicAlbum: vi.fn(),
     getPublicPhotos: vi.fn().mockResolvedValue({ items: [], nextCursor: null, hasMore: false }),
+    getPublicPhoto: vi.fn(),
   };
 });
 
 const mockedGetPublicAlbum = vi.mocked(getPublicAlbum);
+const mockedGetPublicPhoto = vi.mocked(getPublicPhoto);
 
 // 逐挂载独立 i18n + 逐用例卸载（背景见 activity.spec.ts 头注）。
 let i18n: ReturnType<typeof createViewerI18n>;
@@ -49,6 +52,16 @@ describe('viewer routing', () => {
   });
 
   it('deep link resolves token and photoId params on the activity page', async () => {
+    mockedGetPublicPhoto.mockResolvedValue({
+      photoId: 'photo-42',
+      width: 800,
+      height: 500,
+      thumb: { url: 'http://img.test/photo-42-thumb.jpg?s=1', expiresAt: '2026-10-01T00:00:00.000Z' },
+      browse: { url: 'http://img.test/photo-42-browse.jpg?s=1', expiresAt: '2026-10-01T00:00:00.000Z' },
+      likeCount: 0,
+      publishedAt: '2026-10-01T00:00:00.000Z',
+      categoryId: null,
+    });
     await router.push('/a/tok-abc/p/photo-42');
     await router.isReady();
     const wrapper = mount(App, { global: { plugins: [router, i18n] } });
@@ -56,8 +69,10 @@ describe('viewer routing', () => {
     await flushPromises();
 
     expect(mockedGetPublicAlbum).toHaveBeenCalledWith('tok-abc', 'zh-CN');
+    expect(mockedGetPublicPhoto).toHaveBeenCalledWith('tok-abc', 'photo-42');
     expect(wrapper.text()).toContain('2026 公司年会');
-    // photoId 仅用于 Task 8 大图定位，不进入信息区文案。
+    // 深链以大图呈现（solo 序列），id 本身不进入文案。
+    expect(wrapper.find('img.photo').attributes('src')).toBe('http://img.test/photo-42-browse.jpg?s=1');
     expect(wrapper.text()).not.toContain('photo-42');
   });
 });
diff --git a/apps/viewer/src/__tests__/sequence.spec.ts b/apps/viewer/src/__tests__/sequence.spec.ts
new file mode 100644
index 0000000..a96e0af
--- /dev/null
+++ b/apps/viewer/src/__tests__/sequence.spec.ts
@@ -0,0 +1,285 @@
+import { flushPromises, mount, type VueWrapper } from '@vue/test-utils';
+import { defineComponent, ref } from 'vue';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import {
+  ApiError,
+  getPublicPhoto,
+  getPublicPhotos,
+  type PublicPhoto,
+  type PublicPhotoList,
+} from '../api/client';
+import { usePhotoSequence, type PhotoSequence } from '../feed/sequence';
+
+// PhotoSequence（Task 8 数据层）：分页追加去重、深链 solo 条目（就位/自然归位/
+// 越上限保留）、单图签名刷新（换绑/404 移除）与轮询提示。jsdom 下 IO/RO 无关
+// （本层无 DOM 观察者）；轮询用假时钟驱动。
+
+vi.mock('../api/client', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('../api/client')>();
+  return { ...actual, getPublicPhotos: vi.fn(), getPublicPhoto: vi.fn() };
+});
+
+const mockedGetPublicPhotos = vi.mocked(getPublicPhotos);
+const mockedGetPublicPhoto = vi.mocked(getPublicPhoto);
+
+function makePhoto(id: string, width = 800, height = 500): PublicPhoto {
+  return {
+    photoId: id,
+    width,
+    height,
+    thumb: { url: `http://img.test/${id}-thumb.jpg?s=1`, expiresAt: '2026-10-01T00:00:00.000Z' },
+    browse: { url: `http://img.test/${id}-browse.jpg?s=1`, expiresAt: '2026-10-01T00:00:00.000Z' },
+    likeCount: 0,
+    publishedAt: '2026-10-01T00:00:00.000Z',
+  };
+}
+
+function makeList(items: PublicPhoto[], nextCursor: string | null = null): PublicPhotoList {
+  return { items, nextCursor, hasMore: nextCursor !== null };
+}
+
+/** 挂载一个仅创建 sequence 的宿主组件（composable 的 onMounted/watch 需组件上下文）。 */
+function mountSequence(options: { token?: string; category?: string | null } = {}): {
+  wrapper: VueWrapper;
+  sequence: PhotoSequence;
+} {
+  let sequence!: PhotoSequence;
+  const Host = defineComponent({
+    setup() {
+      sequence = usePhotoSequence({
+        token: ref(options.token ?? 'tok-seq'),
+        locale: ref('zh-CN'),
+        category: ref(options.category ?? null),
+      });
+      return () => null;
+    },
+  });
+  const wrapper = mount(Host);
+  return { wrapper, sequence };
+}
+
+describe('photo sequence pagination (Task 8)', () => {
+  beforeEach(() => {
+    mockedGetPublicPhotos.mockReset().mockResolvedValue(makeList([makePhoto('p1'), makePhoto('p2')], 'cur-1'));
+    mockedGetPublicPhoto.mockReset();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it('loads the first page and exposes cursor state', async () => {
+    const { wrapper, sequence } = mountSequence();
+    expect(sequence.initialLoading).toBe(true);
+    await flushPromises();
+
+    expect(mockedGetPublicPhotos).toHaveBeenCalledWith('tok-seq', { locale: 'zh-CN' });
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p1', 'p2']);
+    expect(sequence.initialLoading).toBe(false);
+    expect(sequence.hasMore).toBe(true);
+    expect(sequence.pagesLoaded).toBe(1);
+    wrapper.unmount();
+  });
+
+  it('appends the next page with dedupe and stops at cursor exhaustion', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+    // 第 2 页带回重复 p2（游标边界漂移防御）→ 仅追加新 id。
+    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('p2'), makePhoto('p3')], null));
+
+    await sequence.loadMore();
+    await flushPromises();
+
+    expect(mockedGetPublicPhotos).toHaveBeenLastCalledWith('tok-seq', expect.objectContaining({ cursor: 'cur-1' }));
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p1', 'p2', 'p3']);
+    expect(sequence.hasMore).toBe(false);
+    expect(sequence.pagesLoaded).toBe(2);
+
+    // 游标耗尽后再 loadMore 为无操作（大图导航越过末尾的安全边界）。
+    await sequence.loadMore();
+    expect(mockedGetPublicPhotos).toHaveBeenCalledTimes(2);
+    wrapper.unmount();
+  });
+
+  it('dedupes against an in-flight loadMore (single fetch while pending)', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+
+    let resolvePage!: (value: PublicPhotoList) => void;
+    mockedGetPublicPhotos.mockReturnValueOnce(
+      new Promise<PublicPhotoList>((resolve) => {
+        resolvePage = resolve;
+      }),
+    );
+    void sequence.loadMore();
+    void sequence.loadMore();
+    await flushPromises();
+    expect(mockedGetPublicPhotos).toHaveBeenCalledTimes(2);
+
+    resolvePage(makeList([makePhoto('p9')], null));
+    await flushPromises();
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p1', 'p2', 'p9']);
+    wrapper.unmount();
+  });
+});
+
+describe('photo sequence deep-link solo entries (Task 8)', () => {
+  beforeEach(() => {
+    mockedGetPublicPhotos.mockReset().mockResolvedValue(makeList([makePhoto('p1'), makePhoto('p2')], null));
+    mockedGetPublicPhoto.mockReset();
+  });
+
+  it('ensureInSequence returns the existing index without duplicating', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+
+    expect(sequence.ensureInSequence(makePhoto('p2'))).toBe(1);
+    expect(sequence.photos).toHaveLength(2);
+    expect(sequence.isSolo('p2')).toBe(false);
+    wrapper.unmount();
+  });
+
+  it('appends an unknown photo as a solo entry navigable at the tail', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+
+    const index = sequence.ensureInSequence(makePhoto('p9'));
+    expect(index).toBe(2);
+    expect(sequence.isSolo('p9')).toBe(true);
+    expect(sequence.photos[2]?.photoId).toBe('p9');
+    wrapper.unmount();
+  });
+
+  it('replaces the solo copy with its natural position when a later page brings it', async () => {
+    mockedGetPublicPhotos.mockReset();
+    mockedGetPublicPhotos
+      .mockResolvedValueOnce(makeList([makePhoto('p1'), makePhoto('p2')], 'cur-1'))
+      .mockResolvedValueOnce(makeList([makePhoto('p4'), makePhoto('p9')], null));
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+    sequence.ensureInSequence(makePhoto('p9')); // 深链目标不在第 1 页
+
+    // 相邻页把 p4 与 p9 带回：solo 副本被自然位置副本取代，顺序纠正。
+    await sequence.loadMore();
+    await flushPromises();
+
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p1', 'p2', 'p4', 'p9']);
+    expect(sequence.isSolo('p9')).toBe(false);
+    expect(sequence.indexOf('p9')).toBe(3);
+    wrapper.unmount();
+  });
+
+  it('keeps surviving solos across a full reset, and drops ones covered by the page', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+    sequence.ensureInSequence(makePhoto('p9')); // 保留
+    sequence.ensureInSequence(makePhoto('p2')); // 第 1 页含 p2 → 自然副本接管
+
+    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('p2'), makePhoto('p1')], null));
+    await sequence.resetAndLoad();
+    await flushPromises();
+
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p2', 'p1', 'p9']);
+    expect(sequence.isSolo('p9')).toBe(true);
+    expect(sequence.isSolo('p2')).toBe(false);
+    wrapper.unmount();
+  });
+
+  it('removes a photo from the sequence (404 removal path)', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+
+    sequence.removePhoto('p1');
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p2']);
+    expect(sequence.indexOf('p1')).toBe(-1);
+    wrapper.unmount();
+  });
+});
+
+describe('photo sequence url refresh (Task 8)', () => {
+  beforeEach(() => {
+    mockedGetPublicPhotos.mockReset().mockResolvedValue(makeList([makePhoto('p1'), makePhoto('p2')], null));
+    mockedGetPublicPhoto.mockReset();
+  });
+
+  it('replaces signed urls in place on success', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+    mockedGetPublicPhoto.mockResolvedValue({
+      ...makePhoto('p1'),
+      categoryId: null,
+      thumb: { url: 'http://img.test/p1-thumb.jpg?s=2', expiresAt: '2026-10-01T01:00:00.000Z' },
+      browse: { url: 'http://img.test/p1-browse.jpg?s=2', expiresAt: '2026-10-01T01:00:00.000Z' },
+    });
+
+    expect(await sequence.refreshPhotoUrls('p1')).toBe('replaced');
+    expect(sequence.photos[0]?.browse.url).toBe('http://img.test/p1-browse.jpg?s=2');
+    expect(sequence.photos[0]?.thumb.url).toBe('http://img.test/p1-thumb.jpg?s=2');
+    wrapper.unmount();
+  });
+
+  it('removes the photo on PHOTO_NOT_PUBLIC', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+    mockedGetPublicPhoto.mockRejectedValue(new ApiError('PHOTO_NOT_PUBLIC', 'gone', 404, 'req-1'));
+
+    expect(await sequence.refreshPhotoUrls('p1')).toBe('removed');
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p2']);
+    wrapper.unmount();
+  });
+
+  it('keeps the photo on transient failures', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+    mockedGetPublicPhoto.mockRejectedValue(new ApiError('NETWORK_ERROR', 'down', 0, null));
+
+    expect(await sequence.refreshPhotoUrls('p1')).toBe('failed');
+    expect(sequence.photos).toHaveLength(2);
+    wrapper.unmount();
+  });
+});
+
+describe('photo sequence polling (Task 8)', () => {
+  beforeEach(() => {
+    mockedGetPublicPhotos.mockReset().mockResolvedValue(makeList([makePhoto('p1'), makePhoto('p2')], null));
+    mockedGetPublicPhoto.mockReset();
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it('raises the hint when page 1 contains an unknown id; refresh scrolls top', async () => {
+    const scrollTo = vi.spyOn(window, 'scrollTo').mockImplementation(() => {});
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+    expect(sequence.hasNew).toBe(false);
+
+    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('p9'), makePhoto('p1')], null));
+    vi.advanceTimersByTime(30_000);
+    await flushPromises();
+    expect(sequence.hasNew).toBe(true);
+    expect(sequence.photos).toHaveLength(2); // 只亮提示不自动插入
+
+    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('p9'), makePhoto('p1'), makePhoto('p2')], null));
+    await sequence.refreshFromHint();
+    await flushPromises();
+    expect(sequence.hasNew).toBe(false);
+    expect(sequence.photos.map((p) => p.photoId)).toEqual(['p9', 'p1', 'p2']);
+    expect(scrollTo).toHaveBeenCalledWith(0, 0);
+    wrapper.unmount();
+  });
+
+  it('stays silent when a poll fails', async () => {
+    const { wrapper, sequence } = mountSequence();
+    await flushPromises();
+
+    mockedGetPublicPhotos.mockRejectedValueOnce(new ApiError('INTERNAL_ERROR', 'boom', 500, 'req-1'));
+    vi.advanceTimersByTime(30_000);
+    await flushPromises();
+    expect(sequence.hasNew).toBe(false);
+    expect(sequence.initialErrorKey).toBe(null);
+    wrapper.unmount();
+  });
+});
diff --git a/apps/viewer/src/__tests__/viewer-route.spec.ts b/apps/viewer/src/__tests__/viewer-route.spec.ts
new file mode 100644
index 0000000..38655f2
--- /dev/null
+++ b/apps/viewer/src/__tests__/viewer-route.spec.ts
@@ -0,0 +1,188 @@
+import { flushPromises, mount, type VueWrapper } from '@vue/test-utils';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import App from '../App.vue';
+import { ApiError, getPublicAlbum, getPublicPhoto, getPublicPhotos, type PublicPhoto, type PublicPhotoList } from '../api/client';
+import { createViewerI18n } from '../i18n';
+import { router } from '../router';
+import { makeAlbum } from './fixtures';
+
+// 大图查看器路由编排（Task 8）：URL 同步（打开 push / 切换 replace / 关闭 back 或
+// replace）、滚动锚点恢复、深链解析顺序（单图先行 → 相邻页构成序列）、深链 404
+// 本地化提示与返回链接。使用真实 router 单例（jsdom 提供_history），对齐
+// routing.spec.ts 的既定模式；api 三端点替身。
+
+vi.mock('../api/client', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('../api/client')>();
+  return {
+    ...actual,
+    getPublicAlbum: vi.fn(),
+    getPublicPhotos: vi.fn(),
+    getPublicPhoto: vi.fn(),
+  };
+});
+
+const mockedGetPublicAlbum = vi.mocked(getPublicAlbum);
+const mockedGetPublicPhotos = vi.mocked(getPublicPhotos);
+const mockedGetPublicPhoto = vi.mocked(getPublicPhoto);
+
+function makePhoto(id: string): PublicPhoto {
+  return {
+    photoId: id,
+    width: 800,
+    height: 500,
+    thumb: { url: `http://img.test/${id}-thumb.jpg?s=1`, expiresAt: '2026-10-01T00:00:00.000Z' },
+    browse: { url: `http://img.test/${id}-browse.jpg?s=1`, expiresAt: '2026-10-01T00:00:00.000Z' },
+    likeCount: 0,
+    publishedAt: '2026-10-01T00:00:00.000Z',
+  };
+}
+
+function makeList(items: PublicPhoto[], nextCursor: string | null = null): PublicPhotoList {
+  return { items, nextCursor, hasMore: nextCursor !== null };
+}
+
+let i18n: ReturnType<typeof createViewerI18n>;
+const mounted: VueWrapper[] = [];
+
+function mountApp(): VueWrapper {
+  const wrapper = mount(App, { global: { plugins: [router, i18n] } });
+  mounted.push(wrapper);
+  return wrapper;
+}
+
+function keydown(key: string): void {
+  window.dispatchEvent(new KeyboardEvent('keydown', { key, cancelable: true }));
+}
+
+describe('viewer url sync and deep link (Task 8)', () => {
+  beforeEach(async () => {
+    localStorage.clear();
+    i18n = createViewerI18n('zh-CN');
+    mockedGetPublicAlbum.mockReset().mockResolvedValue(makeAlbum());
+    mockedGetPublicPhotos.mockReset().mockResolvedValue(makeList([makePhoto('p1'), makePhoto('p2'), makePhoto('p3')]));
+    mockedGetPublicPhoto.mockReset().mockImplementation(async (_token, photoId) => ({
+      ...makePhoto(photoId),
+      categoryId: null,
+    }));
+  });
+
+  afterEach(() => {
+    while (mounted.length > 0) {
+      mounted.pop()?.unmount();
+    }
+    vi.restoreAllMocks();
+    vi.unstubAllGlobals();
+  });
+
+  it('open pushes the photo route, navigate replaces, close restores scroll and pops back', async () => {
+    await router.push('/a/tok-view');
+    await router.isReady();
+    const wrapper = mountApp();
+    await flushPromises();
+    expect(wrapper.findAll('.cell')).toHaveLength(3);
+
+    const pushSpy = vi.spyOn(router, 'push');
+    const replaceSpy = vi.spyOn(router, 'replace');
+    const scrollTo = vi.spyOn(window, 'scrollTo').mockImplementation(() => {});
+    vi.stubGlobal('scrollY', 650);
+
+    // 点击第 2 格开大图：push 深链路由，browse 渲染。
+    await wrapper.findAll('.cell')[1].trigger('click');
+    await flushPromises();
+    expect(wrapper.find('img.photo').attributes('src')).toBe('http://img.test/p2-browse.jpg?s=1');
+    expect(router.currentRoute.value.path).toBe('/a/tok-view/p/p2');
+    expect(pushSpy).toHaveBeenCalledTimes(1);
+
+    // 键盘右切：replace（不新增历史条目）。
+    keydown('ArrowRight');
+    await flushPromises();
+    expect(router.currentRoute.value.path).toBe('/a/tok-view/p/p3');
+    expect(replaceSpy).toHaveBeenCalledTimes(1);
+    expect(pushSpy).toHaveBeenCalledTimes(1);
+
+    // Esc 关闭：恢复滚动锚点 + 历史出栈回相册路由（jsdom 的 popstate 异步，需等待）。
+    scrollTo.mockClear();
+    keydown('Escape');
+    await vi.waitFor(() => expect(router.currentRoute.value.path).toBe('/a/tok-view'));
+    expect(wrapper.find('.lightbox').exists()).toBe(false);
+    expect(scrollTo).toHaveBeenCalledWith(0, 650);
+    expect(replaceSpy).toHaveBeenCalledTimes(1); // 关闭未额外 replace
+  });
+
+  it('browser back from the photo route closes the lightbox without touching history further', async () => {
+    await router.push('/a/tok-view');
+    await router.isReady();
+    const wrapper = mountApp();
+    await flushPromises();
+
+    vi.stubGlobal('scrollY', 320);
+    const scrollTo = vi.spyOn(window, 'scrollTo').mockImplementation(() => {});
+    await wrapper.findAll('.cell')[0].trigger('click');
+    await flushPromises();
+    expect(wrapper.find('.lightbox').exists()).toBe(true);
+
+    scrollTo.mockClear();
+    router.back(); // 等价浏览器后退（popstate 异步派发）
+    await vi.waitFor(() => expect(router.currentRoute.value.path).toBe('/a/tok-view'));
+    await flushPromises();
+    expect(wrapper.find('.lightbox').exists()).toBe(false);
+    expect(scrollTo).toHaveBeenCalledWith(0, 320);
+  });
+
+  it('deep link renders the single photo first, then naturalizes it as pages arrive', async () => {
+    // 第 1 页挂起（受控）：验证「先单图、后序列」的解析顺序。
+    let resolveFirstPage!: (value: PublicPhotoList) => void;
+    mockedGetPublicPhotos.mockReset();
+    mockedGetPublicPhotos
+      .mockReturnValueOnce(
+        new Promise<PublicPhotoList>((resolve) => {
+          resolveFirstPage = resolve;
+        }),
+      )
+      .mockResolvedValueOnce(makeList([makePhoto('p4'), makePhoto('p5')], null));
+
+    await router.push('/a/tok-view/p/p5');
+    await router.isReady();
+    const wrapper = mountApp();
+    await flushPromises();
+
+    // 单图先行：列表仍在加载，大图已可看（solo 序列 1/1）。
+    expect(mockedGetPublicPhoto).toHaveBeenCalledWith('tok-view', 'p5');
+    expect(wrapper.find('img.photo').attributes('src')).toBe('http://img.test/p5-browse.jpg?s=1');
+    expect(wrapper.find('.counter').text()).toBe('1 / 1');
+
+    // 第 1 页到达（无 p5）→ 深链 watcher 追拉第 2 页 → p5 归位自然顺序（5/5）。
+    resolveFirstPage(makeList([makePhoto('p1'), makePhoto('p2'), makePhoto('p3')], 'cur-1'));
+    await vi.waitFor(() => expect(wrapper.findAll('.cell')).toHaveLength(5));
+    expect(wrapper.find('.counter').text()).toBe('5 / 5');
+
+    // 序列已构成：左切到前一张。
+    keydown('ArrowLeft');
+    await flushPromises();
+    expect(wrapper.find('img.photo').attributes('src')).toBe('http://img.test/p4-browse.jpg?s=1');
+    expect(router.currentRoute.value.path).toBe('/a/tok-view/p/p4');
+  });
+
+  it('deep link to a non-public photo shows the localized notice with a back link', async () => {
+    mockedGetPublicPhoto.mockRejectedValue(new ApiError('PHOTO_NOT_PUBLIC', 'hidden', 404, 'req-1'));
+
+    await router.push('/a/tok-view/p/gone');
+    await router.isReady();
+    const wrapper = mountApp();
+    await flushPromises();
+
+    expect(wrapper.find('.lightbox').exists()).toBe(false);
+    const notice = wrapper.find('.deep-link-notice[role="alert"]');
+    expect(notice.text()).toContain('照片不存在或已下线');
+    expect(notice.text()).not.toContain('PHOTO_NOT_PUBLIC'); // 不裸露错误码
+
+    const back = notice.find('a');
+    expect(back.text()).toBe('返回相册');
+    expect(back.attributes('href')).toBe('/a/tok-view');
+    await back.trigger('click');
+    await flushPromises();
+    expect(router.currentRoute.value.path).toBe('/a/tok-view');
+    expect(wrapper.find('.deep-link-notice').exists()).toBe(false);
+    expect(wrapper.text()).toContain('2026 公司年会');
+  });
+});
diff --git a/apps/viewer/src/__tests__/zoom.spec.ts b/apps/viewer/src/__tests__/zoom.spec.ts
new file mode 100644
index 0000000..06837d2
--- /dev/null
+++ b/apps/viewer/src/__tests__/zoom.spec.ts
@@ -0,0 +1,64 @@
+import { describe, expect, it } from 'vitest';
+import {
+  INITIAL_ZOOM,
+  MAX_SCALE,
+  MIN_SCALE,
+  clampScale,
+  panBy,
+  resetZoom,
+  wheelFactor,
+  zoomAt,
+  type ZoomState,
+} from '../viewer/zoom';
+
+// 大图查看器缩放状态机（Task 8）纯函数层：钳制、不动点缩放、平移门控与复位。
+
+describe('zoom state machine (Task 8)', () => {
+  it('clamps scale into [1, 4]', () => {
+    expect(clampScale(0.2)).toBe(MIN_SCALE);
+    expect(clampScale(3.9)).toBe(3.9);
+    expect(clampScale(11)).toBe(MAX_SCALE);
+  });
+
+  it('zooms around the given anchor point: the anchor stays fixed on screen', () => {
+    const state: ZoomState = { scale: 1, tx: 0, ty: 0 };
+    // 锚点 (100, 40)（相对图片中心）：缩放前屏幕位置 = 100*1+0 = 100。
+    const next = zoomAt(state, 2, 100, 40);
+    expect(next.scale).toBe(2);
+    expect(next.tx).toBe(100 * (1 - 2));
+    expect(next.ty).toBe(40 * (1 - 2));
+    // 锚点屏幕位置不变：100*2 + (-100) = 100。
+    expect(100 * next.scale + next.tx).toBe(100);
+    expect(40 * next.scale + next.ty).toBe(40);
+  });
+
+  it('clamps at max scale and keeps the anchor fixed with the actual factor', () => {
+    const state: ZoomState = { scale: 3, tx: -50, ty: 20 };
+    const next = zoomAt(state, 10, 200, 0);
+    expect(next.scale).toBe(MAX_SCALE);
+    // 实际因子 4/3；锚点 200*3-50 = 550 → 200*4 + tx' = 550 → tx' = -250。
+    expect(200 * next.scale + next.tx).toBe(200 * state.scale + state.tx);
+  });
+
+  it('resets translation when scale returns to min', () => {
+    const state: ZoomState = { scale: 2, tx: -120, ty: 80 };
+    const next = zoomAt(state, 0.1, 300, 300);
+    expect(next).toEqual(resetZoom());
+  });
+
+  it('pans only when zoomed in; pan accumulates', () => {
+    const flat: ZoomState = { ...INITIAL_ZOOM };
+    expect(panBy(flat, 40, 20)).toBe(flat); // scale=1：无平移空间
+
+    const zoomed = zoomAt(flat, 2, 0, 0);
+    const panned = panBy(panBy(zoomed, 10, -5), 6, 6);
+    expect(panned.tx).toBe(16);
+    expect(panned.ty).toBe(1);
+  });
+
+  it('wheel factor maps deltaY sign consistently and stays continuous', () => {
+    expect(wheelFactor(-120)).toBeGreaterThan(1); // 上滚/外张 → 放大
+    expect(wheelFactor(120)).toBeLessThan(1); // 下滚/内收 → 缩小
+    expect(wheelFactor(0)).toBe(1);
+  });
+});
diff --git a/apps/viewer/src/components/PhotoFeed.vue b/apps/viewer/src/components/PhotoFeed.vue
index a9d7907..9732177 100644
--- a/apps/viewer/src/components/PhotoFeed.vue
+++ b/apps/viewer/src/components/PhotoFeed.vue
@@ -1,120 +1,47 @@
 <script setup lang="ts">
-import { computed, onBeforeUnmount, onMounted, reactive, ref, watch } from 'vue';
+import { computed, onBeforeUnmount, reactive, ref, watch } from 'vue';
 import { useI18n } from 'vue-i18n';
-import {
-  ApiError,
-  NETWORK_ERROR_CODE,
-  getPublicPhoto,
-  getPublicPhotos,
-  type PublicPhoto,
-  type PublicPhotoList,
-} from '../api/client';
-import { errorMessageKey } from '../api/errors';
-import { containsNewPhotoId, layoutWaterfall, mergeUniqueByPhotoId } from '../feed/layout';
+import type { PublicPhoto } from '../api/client';
+import type { PhotoSequence } from '../feed/sequence';
+import { layoutWaterfall } from '../feed/layout';
 
-// 观众瀑布流（Task 7）：双列绝对定位（短列优先，条目高按 browse 宽高比例预留）
-// + IntersectionObserver 懒加载 + 游标无限滚动 + 分类筛选 + 新照片轮询提示。
+// 观众瀑布流（Task 7；Task 8 起数据层上提）：双列绝对定位（短列优先，条目高按
+// browse 宽高比例预留）+ IntersectionObserver 懒加载 + 哨兵无限滚动 + 新照片提示条。
+// 数据生命周期（分页/去重/轮询/深链 solo）在 ActivityPage 创建的 PhotoSequence
+// composable（feed/sequence.ts）——feed 与大图查看器共享同一序列，切换大图时
+// 保持浏览顺序、越过末尾自动扩展。
 //
-// 关键决策：
-//   · 懒加载 = 仅当单元格接近视口才绑定 <img src>（等价 data-src → src 换绑）；
-//     shownIds 集合跨刷新保留——刷新只换签名 URL，同 id 单元格不必重新判定；
-//     IO 不可用（旧环境/jsdom）时退化为立即加载，功能不缺失。
-//   · 图片 onerror 重试一次：调单图端点换新签名 URL 再换绑；再失败则收起该图
-//     （占位底色仍在，布局因高度预留不跳动）。
-//   · 轮询（30s，e2e 可用 window.__viewerPollMs 覆盖）只取第 1 页对比 id 集合，
-//     命中新照片只亮提示条——不自动插入（避免滚动位置跳动，需求 1.2）；
-//     点击提示条 = 整表刷新回第 1 页并回顶。标签页隐藏暂停（R26 同精神）。
-//   · 竞态防护：feedSequence 令牌——分类/语言/token 切换或刷新会使在途的
-//     分页/轮询结果作废；轮询失败静默（网络抖动不应打扰观众）。
+// 关键决策（沿用 Task 7）：
+//   · 懒加载 = 仅当单元格接近视口才绑定 <img src>；shownIds 集合跨刷新保留——
+//     刷新只换签名 URL，同 id 单元格不必重新判定；IO 不可用（旧环境/jsdom）时
+//     退化为立即加载，功能不缺失。
+//   · 图片 onerror 重试一次：经 sequence.refreshPhotoUrls 换新签名 URL 再换绑；
+//     再失败（或照片已下线）则收起该图（占位底色仍在，布局因高度预留不跳动）。
+//   · 单元格点击 emit('open', photoId) → ActivityPage 打开大图（Task 8）。
 
 const props = defineProps<{
-  token: string;
-  locale: string;
-  /** 当前分类筛选（null = 全部）。由活动页 chips 持有，切换即重置列表。 */
-  category: string | null;
+  sequence: PhotoSequence;
+}>();
+
+const emit = defineEmits<{
+  open: [photoId: string];
 }>();
 
 const { t } = useI18n();
 
-const photos = ref<PublicPhoto[]>([]);
-const nextCursor = ref<string | null>(null);
-const hasMore = ref(false);
-const initialLoading = ref(true);
-const initialErrorKey = ref<string | null>(null);
-const loadingMore = ref(false);
-const moreFailed = ref(false);
-const hasNew = ref(false);
+const photos = computed(() => props.sequence.photos);
+const initialLoading = computed(() => props.sequence.initialLoading);
+const initialErrorKey = computed(() => props.sequence.initialErrorKey);
+const loadingMore = computed(() => props.sequence.loadingMore);
+const moreFailed = computed(() => props.sequence.moreFailed);
+const hasMore = computed(() => props.sequence.hasMore);
+const hasNew = computed(() => props.sequence.hasNew);
 
 // 懒加载/重试视图状态（按 photoId，跨刷新保留，见顶部决策注）。
 const shownIds = reactive(new Set<string>());
 const retriedIds = reactive(new Set<string>());
 const failedIds = reactive(new Set<string>());
 
-let feedSequence = 0;
-
-function fetchPage(cursor?: string): Promise<PublicPhotoList> {
-  return getPublicPhotos(props.token, {
-    locale: props.locale,
-    category: props.category ?? undefined,
-    cursor,
-  });
-}
-
-/** 整表重置加载（首载/分类切换/语言切换/token 切换/新照片刷新共用）。 */
-async function resetAndLoad(): Promise<void> {
-  const sequence = ++feedSequence;
-  initialLoading.value = true;
-  initialErrorKey.value = null;
-  moreFailed.value = false;
-  loadingMore.value = false;
-  hasNew.value = false;
-  photos.value = [];
-  nextCursor.value = null;
-  hasMore.value = false;
-  pruneCellElements();
-  try {
-    const page = await fetchPage();
-    if (sequence !== feedSequence) return;
-    photos.value = [...page.items];
-    nextCursor.value = page.nextCursor;
-    hasMore.value = page.hasMore && page.nextCursor !== null;
-  } catch (error) {
-    if (sequence !== feedSequence) return;
-    const code = error instanceof ApiError ? error.code : NETWORK_ERROR_CODE;
-    initialErrorKey.value = errorMessageKey(code);
-  } finally {
-    if (sequence === feedSequence) initialLoading.value = false;
-  }
-}
-
-/** 无限滚动：哨兵进入视口（600px 预载）时取下一页；去重防御性合并。 */
-async function loadMore(): Promise<void> {
-  if (initialLoading.value || initialErrorKey.value !== null) return;
-  if (loadingMore.value || !hasMore.value || nextCursor.value === null) return;
-  const sequence = feedSequence;
-  loadingMore.value = true;
-  moreFailed.value = false;
-  try {
-    const page = await fetchPage(nextCursor.value);
-    if (sequence !== feedSequence) return;
-    photos.value = mergeUniqueByPhotoId(photos.value, page.items);
-    nextCursor.value = page.nextCursor;
-    hasMore.value = page.hasMore && page.nextCursor !== null;
-    pruneCellElements();
-  } catch {
-    if (sequence === feedSequence) moreFailed.value = true;
-  } finally {
-    if (sequence === feedSequence) loadingMore.value = false;
-  }
-}
-
-/** 新照片提示条点击：整表刷新回第 1 页并回顶（提示消失）。 */
-async function refreshFromHint(): Promise<void> {
-  if (initialLoading.value) return;
-  await resetAndLoad();
-  window.scrollTo(0, 0);
-}
-
 // —— 布局：容器宽 → 纯函数双列放置（ResizeObserver 跟踪容器宽度变化） ——
 
 const trackEl = ref<HTMLElement | null>(null);
@@ -191,15 +118,22 @@ function pruneCellElements(): void {
   }
 }
 
+watch(
+  photos,
+  () => pruneCellElements(),
+);
+
 watch(
   sentinelEl,
   (el) => {
     sentinelObserver?.disconnect();
     sentinelObserver = null;
     if (el === null) return;
+    // IO 不可用（jsdom/旧环境）时不观察：无限滚动退化为已加载内容（不崩溃）。
+    if (typeof IntersectionObserver === 'undefined') return;
     sentinelObserver = new IntersectionObserver(
       (entries) => {
-        if (entries.some((entry) => entry.isIntersecting)) void loadMore();
+        if (entries.some((entry) => entry.isIntersecting)) void props.sequence.loadMore();
       },
       { rootMargin: '600px 0px' },
     );
@@ -208,99 +142,28 @@ watch(
   { flush: 'post' },
 );
 
-/** 缩略图加载失败：重试一次（单图端点换新签名 URL）；再失败收起图片。 */
+/** 缩略图加载失败：重试一次（单图端点换新签名 URL）；再失败/已下线则收起图片。 */
 async function onImgError(photo: PublicPhoto): Promise<void> {
-  const { photoId } = photo;
-  if (failedIds.has(photoId)) return;
-  if (retriedIds.has(photoId)) {
-    failedIds.add(photoId);
+  if (failedIds.has(photo.photoId)) return;
+  if (retriedIds.has(photo.photoId)) {
+    failedIds.add(photo.photoId);
     return;
   }
-  retriedIds.add(photoId);
-  try {
-    const detail = await getPublicPhoto(props.token, photoId);
-    photo.thumb = detail.thumb;
-    photo.browse = detail.browse;
-  } catch {
-    failedIds.add(photoId);
-  }
+  retriedIds.add(photo.photoId);
+  const result = await props.sequence.refreshPhotoUrls(photo.photoId);
+  if (result !== 'replaced') failedIds.add(photo.photoId);
 }
 
-// —— 新照片轮询 ——
-
-const DEFAULT_POLL_INTERVAL_MS = 30_000;
-
-/** e2e/开发注入点：window.__viewerPollMs 覆盖轮询间隔（仅测试加速用）。 */
-function pollIntervalMs(): number {
-  const override = (globalThis as { __viewerPollMs?: unknown }).__viewerPollMs;
-  return typeof override === 'number' && override > 0 ? override : DEFAULT_POLL_INTERVAL_MS;
-}
-
-let pollTimer: ReturnType<typeof setInterval> | undefined;
-
-function stopPolling(): void {
-  if (pollTimer !== undefined) {
-    clearInterval(pollTimer);
-    pollTimer = undefined;
-  }
-}
-
-function startPolling(): void {
-  stopPolling();
-  pollTimer = setInterval(() => void pollOnce(), pollIntervalMs());
-}
-
-/** 取当前筛选的第 1 页对比 id 集合；发现新照片只亮提示条（不自动插入）。失败静默。 */
-async function pollOnce(): Promise<void> {
-  if (
-    document.hidden ||
-    initialLoading.value ||
-    initialErrorKey.value !== null ||
-    hasNew.value
-  ) {
-    return;
-  }
-  const sequence = feedSequence;
-  try {
-    const page = await fetchPage();
-    if (sequence !== feedSequence) return;
-    if (containsNewPhotoId(photos.value.map((photo) => photo.photoId), page.items)) {
-      hasNew.value = true;
-    }
-  } catch {
-    // 轮询失败静默：网络抖动不打扰观众（下一次间隔重试）。
-  }
-}
-
-function onVisibilityChange(): void {
-  if (document.hidden) stopPolling();
-  else startPolling();
-}
-
-onMounted(() => {
-  void resetAndLoad();
-  startPolling();
-  document.addEventListener('visibilitychange', onVisibilityChange);
-});
-
 onBeforeUnmount(() => {
-  stopPolling();
-  document.removeEventListener('visibilitychange', onVisibilityChange);
   lazyObserver?.disconnect();
   sentinelObserver?.disconnect();
   resizeObserver?.disconnect();
 });
-
-// 分类/语言/token 变化：整表重置（语言切换保留当前分类——由 props 自带）。
-watch(
-  [() => props.token, () => props.locale, () => props.category],
-  () => void resetAndLoad(),
-);
 </script>
 
 <template>
   <div class="photo-feed">
-    <button v-if="hasNew" type="button" class="new-photo-bar" @click="refreshFromHint">
+    <button v-if="hasNew" type="button" class="new-photo-bar" @click="props.sequence.refreshFromHint()">
       {{ t('album.newPhotos') }}
     </button>
 
@@ -308,7 +171,7 @@ watch(
 
     <div v-else-if="initialErrorKey !== null" class="error" role="alert">
       <p>{{ t(initialErrorKey) }}</p>
-      <button type="button" @click="resetAndLoad">{{ t('album.retry') }}</button>
+      <button type="button" @click="props.sequence.resetAndLoad">{{ t('album.retry') }}</button>
     </div>
 
     <div v-else-if="photos.length === 0" class="feed">
@@ -328,6 +191,7 @@ watch(
             width: `${layout.columnWidth}px`,
             height: `${placement.height}px`,
           }"
+          @click="emit('open', photos[placement.index].photoId)"
         >
           <img
             v-if="shownIds.has(photos[placement.index].photoId) && !failedIds.has(photos[placement.index].photoId)"
@@ -343,7 +207,7 @@ watch(
 
       <p v-if="loadingMore" class="status more-status">{{ t('album.loadingMore') }}</p>
       <div v-else-if="moreFailed" class="more-failed">
-        <button type="button" @click="loadMore">{{ t('album.retry') }}</button>
+        <button type="button" @click="props.sequence.loadMore">{{ t('album.retry') }}</button>
       </div>
       <p v-else-if="!hasMore" class="end-note">{{ t('album.end') }}</p>
 
@@ -412,6 +276,7 @@ watch(
   border-radius: 6px;
   overflow: hidden;
   background: linear-gradient(160deg, #f3f4f6, #e5e7eb);
+  cursor: pointer;
 }
 .cell-img {
   display: block;
diff --git a/apps/viewer/src/components/PhotoLightbox.vue b/apps/viewer/src/components/PhotoLightbox.vue
new file mode 100644
index 0000000..20688ac
--- /dev/null
+++ b/apps/viewer/src/components/PhotoLightbox.vue
@@ -0,0 +1,458 @@
+<script setup lang="ts">
+import { computed, onBeforeUnmount, onMounted, reactive, ref, watch } from 'vue';
+import { useI18n } from 'vue-i18n';
+import type { PhotoSequence } from '../feed/sequence';
+import { MIN_SCALE, panBy, resetZoom, wheelFactor, zoomAt, type ZoomState } from '../viewer/zoom';
+
+// 大图查看器（Task 8）：browse URL 全屏展示 + 左右切换（保持列表浏览序列，越过
+// 末尾且 hasMore 时取下一页扩展）+ 滚轮/双指缩放与平移（受控 CSS transform，数学
+// 见 viewer/zoom.ts）+ 签名过期静默重取（复用 sequence.refreshPhotoUrls）。
+//
+// 状态归属：序列数据/分页在 ActivityPage 创建的 PhotoSequence（共享 composable），
+// 本组件只持视图态（缩放/平移、加载失败标记、扩展中标记）；当前照片以 photoId
+// （v-model）为准而非下标——序列追加/solo 归位/条目移除都会移动下标，photoId 键
+// 控让重排自动保持指向同一张照片。
+//
+// 手势（Pointer Events，无第三方依赖）：
+//   · 双指：捏合缩放（transform 不动点 = 手势中心）+ 中点漂移平移；
+//   · 单指且 scale>1：拖拽平移；scale=1：横向轻扫切换上一张/下一张；
+//   · 双击（鼠标 dblclick / 触控双 tap）：复位缩放；
+//   · 滚轮（无需 ctrl）：以光标为不动点缩放；Esc/关闭按钮/背景点击关闭。
+//
+// 关闭回位（滚动锚点）与 URL 同步由 ActivityPage 负责（见 ActivityPage 注释）。
+
+const props = defineProps<{
+  sequence: PhotoSequence;
+  photoId: string;
+}>();
+
+const emit = defineEmits<{
+  'update:photoId': [photoId: string];
+  /** 当前照片经刷新确认已下线（404）：neighborIndex 为移除前下标，供回退邻居。 */
+  removed: [photoId: string, neighborIndex: number];
+  close: [];
+}>();
+
+const { t } = useI18n();
+
+const photos = computed(() => props.sequence.photos);
+const index = computed(() => photos.value.findIndex((photo) => photo.photoId === props.photoId));
+const photo = computed(() => photos.value[index.value] ?? null);
+const total = computed(() => photos.value.length);
+const hasPrev = computed(() => index.value > 0);
+// 末张且仍有下一页 → 允许继续向右（导航触发序列扩展）。
+const hasNext = computed(() => index.value < total.value - 1 || props.sequence.hasMore);
+
+// —— 视图状态（按 photoId；切换照片即复位） ——
+
+/** 图片单次重试的缓存击穿键：重试按钮点击后 +1 强制 <img> 重挂载重触发加载。 */
+const retryCount = ref(0);
+const failedIds = reactive(new Set<string>());
+const retriedIds = reactive(new Set<string>());
+const extending = ref(false);
+
+watch(
+  () => props.photoId,
+  () => {
+    failedIds.clear();
+    retriedIds.clear();
+    retryCount.value = 0;
+    Object.assign(zoom, resetZoom());
+  },
+);
+
+// —— 缩放/平移 ——
+
+const zoom = reactive<ZoomState>({ ...resetZoom() });
+const rootEl = ref<HTMLElement | null>(null);
+
+const imgStyle = computed(() => ({
+  transform: `translate(${zoom.tx}px, ${zoom.ty}px) scale(${zoom.scale})`,
+}));
+
+/** 手势中心（相对图片未变换时中心的坐标）：图片经 flex 居中，未变换中心 = 容器中心。 */
+function center(): { x: number; y: number } {
+  const rect = rootEl.value?.getBoundingClientRect();
+  if (rect === undefined) return { x: 0, y: 0 };
+  return { x: rect.left + rect.width / 2, y: rect.top + rect.height / 2 };
+}
+
+function onWheel(event: WheelEvent): void {
+  const { x, y } = center();
+  Object.assign(zoom, zoomAt({ ...zoom }, wheelFactor(event.deltaY), event.clientX - x, event.clientY - y));
+}
+
+function onDblClick(): void {
+  Object.assign(zoom, resetZoom());
+}
+
+// —— 指针手势（双指捏合 / 单指平移 / 单指轻扫 / 双 tap 复位） ——
+
+const pointers = new Map<number, { x: number; y: number }>();
+let pinchDistance = 0;
+let pinchMid = { x: 0, y: 0 };
+let swipe: { x: number; y: number; dx: number; dy: number } | null = null;
+let lastTap = { time: 0, x: 0, y: 0 };
+/** 手势期间发生过位移：抑制手势收尾时的背景 click 误关闭。 */
+let dragged = false;
+
+const SWIPE_MIN_DISTANCE = 50;
+
+function pointerPair(): { a: { x: number; y: number }; b: { x: number; y: number } } | null {
+  if (pointers.size < 2) return null;
+  const [first, second] = pointers.values();
+  if (first === undefined || second === undefined) return null;
+  return { a: first, b: second };
+}
+
+function distance(a: { x: number; y: number }, b: { x: number; y: number }): number {
+  return Math.hypot(a.x - b.x, a.y - b.y);
+}
+
+function onPointerDown(event: PointerEvent): void {
+  pointers.set(event.pointerId, { x: event.clientX, y: event.clientY });
+  dragged = false;
+
+  // 触控双 tap：400ms 内同点两落 → 复位缩放。
+  if (event.pointerType === 'touch' && pointers.size === 1) {
+    const now = performance.now();
+    if (now - lastTap.time < 400 && Math.hypot(event.clientX - lastTap.x, event.clientY - lastTap.y) < 40) {
+      Object.assign(zoom, resetZoom());
+      lastTap = { time: 0, x: 0, y: 0 };
+    } else {
+      lastTap = { time: now, x: event.clientX, y: event.clientY };
+    }
+  }
+
+  const pair = pointerPair();
+  if (pair !== null) {
+    pinchDistance = distance(pair.a, pair.b);
+    pinchMid = { x: (pair.a.x + pair.b.x) / 2, y: (pair.a.y + pair.b.y) / 2 };
+    swipe = null;
+  } else if (zoom.scale <= MIN_SCALE) {
+    swipe = { x: event.clientX, y: event.clientY, dx: 0, dy: 0 };
+  }
+}
+
+function onPointerMove(event: PointerEvent): void {
+  const previous = pointers.get(event.pointerId);
+  if (previous === undefined) return;
+  const current = { x: event.clientX, y: event.clientY };
+  pointers.set(event.pointerId, current);
+
+  const pair = pointerPair();
+  if (pair !== null) {
+    // 双指：距离比 → 缩放因子（不动点 = 当前中点）；中点位移 → 平移。
+    const nextDistance = distance(pair.a, pair.b);
+    const mid = { x: (pair.a.x + pair.b.x) / 2, y: (pair.a.y + pair.b.y) / 2 };
+    const { x, y } = center();
+    const factor = pinchDistance > 0 ? nextDistance / pinchDistance : 1;
+    Object.assign(zoom, zoomAt({ ...zoom }, factor, mid.x - x, mid.y - y));
+    Object.assign(zoom, panBy({ ...zoom }, mid.x - pinchMid.x, mid.y - pinchMid.y));
+    pinchDistance = nextDistance;
+    pinchMid = mid;
+    dragged = true;
+    return;
+  }
+
+  if (zoom.scale > MIN_SCALE) {
+    // 单指平移（scale>1）。
+    Object.assign(zoom, panBy({ ...zoom }, current.x - previous.x, current.y - previous.y));
+    dragged = true;
+  } else if (swipe !== null) {
+    swipe.dx = current.x - swipe.x;
+    swipe.dy = current.y - swipe.y;
+    if (Math.abs(swipe.dx) > 10 || Math.abs(swipe.dy) > 10) dragged = true;
+  }
+}
+
+/** 手势结束（抬起/取消/离开全屏层）。不使用 setPointerCapture：捕获会把后续
+   * click 重定向到捕获元素，按钮（关闭/切换）将收不到点击。 */
+function onPointerEnd(event: PointerEvent): void {
+  pointers.delete(event.pointerId);
+  if (pointers.size < 2) pinchDistance = 0;
+  if (pointers.size === 1) {
+    // 双指 → 单指：剩余指针重新作为平移/轻扫基线。
+    const [remaining] = pointers.values();
+    if (remaining !== undefined) {
+      swipe = zoom.scale <= MIN_SCALE ? { x: remaining.x, y: remaining.y, dx: 0, dy: 0 } : null;
+    }
+    return;
+  }
+  if (pointers.size > 0) return;
+
+  const gesture = swipe;
+  swipe = null;
+  if (gesture === null) return;
+  // 以抬起坐标结算总位移（最后一帧 move 可能早于抬起点）。
+  gesture.dx = event.clientX - gesture.x;
+  gesture.dy = event.clientY - gesture.y;
+  if (Math.abs(gesture.dx) > SWIPE_MIN_DISTANCE && Math.abs(gesture.dx) > Math.abs(gesture.dy) * 1.2) {
+    if (gesture.dx < 0) void goTo(index.value + 1);
+    else void goTo(index.value - 1);
+  }
+}
+
+function onBackdropClick(): void {
+  if (dragged) return; // 手势收尾的 click 不关闭
+  emit('close');
+}
+
+// —— 键盘 ——
+
+function onKeydown(event: KeyboardEvent): void {
+  if (event.key === 'Escape') {
+    event.preventDefault();
+    emit('close');
+  } else if (event.key === 'ArrowLeft') {
+    event.preventDefault();
+    void goTo(index.value - 1);
+  } else if (event.key === 'ArrowRight') {
+    event.preventDefault();
+    void goTo(index.value + 1);
+  }
+}
+
+// —— 导航（保持列表浏览序列；越过末尾且 hasMore → 扩展） ——
+
+async function goTo(targetIndex: number): Promise<void> {
+  if (targetIndex < 0 || targetIndex === index.value) return;
+  if (targetIndex >= total.value) {
+    if (!props.sequence.hasMore) return;
+    extending.value = true;
+    try {
+      await props.sequence.loadMore();
+    } finally {
+      extending.value = false;
+    }
+    if (targetIndex >= photos.value.length) return; // 翻页失败/无新增：留在原处
+  }
+  const target = photos.value[targetIndex];
+  if (target === undefined || target.photoId === props.photoId) return;
+  emit('update:photoId', target.photoId);
+}
+
+// 相邻预取（±1 browse URL）+ 临近末尾预拉下一页，让右切更顺滑。
+watch(
+  () => [props.photoId, photos.value] as const,
+  () => {
+    if (index.value === -1) return;
+    for (const neighbor of [index.value - 1, index.value + 1]) {
+      const target = photos.value[neighbor];
+      if (target !== undefined) void preload(target.browse.url);
+    }
+    if (index.value >= photos.value.length - 2 && props.sequence.hasMore && !props.sequence.loadingMore) {
+      void props.sequence.loadMore();
+    }
+  },
+  { immediate: true },
+);
+
+function preload(url: string): void {
+  const img = new Image();
+  img.src = url;
+}
+
+// —— 签名过期/下线处理 ——
+
+/** 大图加载失败：静默重取单图接口换新签名 URL；404 → 通知父级移除；其他失败可重试。 */
+async function onImgError(): Promise<void> {
+  const current = photo.value;
+  if (current === null) return;
+  const { photoId } = current;
+  if (retriedIds.has(photoId)) {
+    failedIds.add(photoId);
+    return;
+  }
+  retriedIds.add(photoId);
+  const neighborIndex = index.value;
+  const result = await props.sequence.refreshPhotoUrls(photoId);
+  if (result === 'replaced') return; // 新签名 URL 换绑后 <img> 自动重载
+  if (result === 'removed') {
+    if (props.photoId === photoId) emit('removed', photoId, neighborIndex);
+    return;
+  }
+  failedIds.add(photoId); // 网络等其他失败：收起图片，展示可重试占位
+}
+
+function retryFailed(): void {
+  const current = photo.value;
+  if (current === null) return;
+  failedIds.delete(current.photoId);
+  retriedIds.delete(current.photoId);
+  retryCount.value += 1; // 强制 <img> 重挂载，重新触发加载/错误链
+}
+
+onMounted(() => {
+  window.addEventListener('keydown', onKeydown);
+});
+
+onBeforeUnmount(() => {
+  window.removeEventListener('keydown', onKeydown);
+});
+</script>
+
+<template>
+  <div
+    v-if="photo !== null"
+    ref="rootEl"
+    class="lightbox"
+    role="dialog"
+    aria-modal="true"
+    :aria-label="t('viewer.title')"
+    @wheel.prevent="onWheel"
+    @pointerdown="onPointerDown"
+    @pointermove="onPointerMove"
+    @pointerup="onPointerEnd"
+    @pointercancel="onPointerEnd"
+    @pointerleave="onPointerEnd"
+    @dblclick="onDblClick"
+  >
+    <div class="backdrop" @click="onBackdropClick" />
+
+    <img
+      v-if="!failedIds.has(photo.photoId)"
+      :key="`${photo.photoId}:${retryCount}`"
+      class="photo"
+      :src="photo.browse.url"
+      :alt="t('route.photoLabel')"
+      :style="imgStyle"
+      draggable="false"
+      @error="onImgError"
+    >
+    <div v-else class="img-failed" role="alert">
+      <p>{{ t('viewer.loadFailed') }}</p>
+      <button type="button" @click="retryFailed">{{ t('album.retry') }}</button>
+    </div>
+
+    <header class="bar">
+      <span class="counter">{{ t('viewer.counter', { current: index + 1, total }) }}</span>
+      <span class="likes">{{ t('viewer.likeCount', { count: photo.likeCount }) }}</span>
+      <!-- P4a 预留：下载 / 分享操作位（P1b 不实现）。 -->
+      <button type="button" class="control close" :aria-label="t('viewer.close')" @click="emit('close')">
+        ✕
+      </button>
+    </header>
+
+    <button
+      type="button"
+      class="control nav prev"
+      :disabled="!hasPrev"
+      :aria-label="t('viewer.previous')"
+      @click="goTo(index - 1)"
+    >
+      ‹
+    </button>
+    <button
+      type="button"
+      class="control nav next"
+      :disabled="!hasNext"
+      :aria-label="t('viewer.next')"
+      @click="goTo(index + 1)"
+    >
+      ›
+    </button>
+
+    <p v-if="extending" class="loading">{{ t('album.loading') }}</p>
+  </div>
+</template>
+
+<style scoped>
+/* 极简基线样式：视觉打磨留待 P4a。 */
+.lightbox {
+  position: fixed;
+  inset: 0;
+  z-index: 100;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  touch-action: none;
+  user-select: none;
+}
+.backdrop {
+  position: absolute;
+  inset: 0;
+  background: rgba(17, 24, 39, 0.92);
+}
+.photo {
+  position: relative;
+  max-width: 100%;
+  max-height: 100%;
+  object-fit: contain;
+  transform-origin: center;
+  will-change: transform;
+}
+.img-failed {
+  position: relative;
+  color: #f3f4f6;
+  text-align: center;
+}
+.img-failed button {
+  margin-top: 8px;
+  border: 1px solid #4b5563;
+  border-radius: 6px;
+  background: transparent;
+  color: #e5e7eb;
+  padding: 4px 12px;
+  cursor: pointer;
+}
+.bar {
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  display: flex;
+  align-items: center;
+  gap: 16px;
+  padding: 10px 16px;
+  color: #f9fafb;
+  background: linear-gradient(rgba(0, 0, 0, 0.45), transparent);
+}
+.counter {
+  font-variant-numeric: tabular-nums;
+}
+.likes {
+  color: #d1d5db;
+  font-size: 0.875rem;
+}
+.control {
+  border: none;
+  background: rgba(17, 24, 39, 0.55);
+  color: #f9fafb;
+  cursor: pointer;
+}
+.control:disabled {
+  opacity: 0.35;
+  cursor: default;
+}
+.control.close {
+  margin-left: auto;
+  font-size: 1.1rem;
+  border-radius: 6px;
+  padding: 4px 10px;
+}
+.control.nav {
+  position: absolute;
+  top: 50%;
+  transform: translateY(-50%);
+  font-size: 2rem;
+  line-height: 1;
+  border-radius: 999px;
+  width: 44px;
+  height: 44px;
+}
+.control.nav.prev {
+  left: 12px;
+}
+.control.nav.next {
+  right: 12px;
+}
+.loading {
+  position: absolute;
+  bottom: 16px;
+  left: 50%;
+  transform: translateX(-50%);
+  margin: 0;
+  color: #d1d5db;
+}
+</style>
diff --git a/apps/viewer/src/feed/sequence.ts b/apps/viewer/src/feed/sequence.ts
new file mode 100644
index 0000000..91f32c3
--- /dev/null
+++ b/apps/viewer/src/feed/sequence.ts
@@ -0,0 +1,264 @@
+import { onBeforeUnmount, onMounted, reactive, ref, watch, type Ref } from 'vue';
+import {
+  ApiError,
+  NETWORK_ERROR_CODE,
+  getPublicPhoto,
+  getPublicPhotos,
+  type PublicPhoto,
+  type PublicPhotoList,
+} from '../api/client';
+import { errorMessageKey } from '../api/errors';
+import { containsNewPhotoId, mergeUniqueByPhotoId } from './layout';
+
+// apps/viewer/src/feed/sequence.ts —— 照片序列状态（Task 7 数据层 / Task 8 提升为
+// feed + lightbox 共享 composable）：游标分页追加、去重合并、轮询新照片提示、
+// 深链 solo 条目与单图签名刷新。
+//
+// 提升决策（计划 Task 8）：大图查看器需要「当前已加载列表序列」做左右切换、越过
+// 末尾时取下一页扩展、深链照片就位/移除——这些都必须与瀑布流共享同一份数组与
+// 游标状态。故把原先 PhotoFeed 内的数据生命周期整体上提至本 composable，由
+// ActivityPage 创建一次，作为参数传给 PhotoFeed（渲染/懒加载/哨兵）与
+// PhotoLightbox（导航/扩展），避免 props 逐层下钻或事件回传面条。
+//
+// solo 机制（深链兜底，文档化折中）：目标照片不在已加载序列时以 solo 条目追加在
+// 序列尾部（indexOf 可见、可导航）；后续任何一页（含整表刷新）带回该 id 时，
+// solo 副本被自然位置副本取代（integratePage），序列顺序自动纠正。ActivityPage
+// 侧最多再拉 DEEP_LINK_PAGE_CAP 页寻找自然位置（见 ActivityPage）。
+
+export interface PhotoSequenceInputs {
+  token: Ref<string>;
+  locale: Ref<string>;
+  category: Ref<string | null>;
+}
+
+/** 单图刷新结果：换绑新签名 URL / 照片已不可公开见（404，已从序列移除）/ 其他失败。 */
+export type PhotoRefreshResult = 'replaced' | 'removed' | 'failed';
+
+export function usePhotoSequence(inputs: PhotoSequenceInputs) {
+  const photos = ref<PublicPhoto[]>([]);
+  const nextCursor = ref<string | null>(null);
+  const hasMore = ref(false);
+  const initialLoading = ref(true);
+  const initialErrorKey = ref<string | null>(null);
+  const loadingMore = ref(false);
+  const moreFailed = ref(false);
+  const hasNew = ref(false);
+  /** 深链解析的页数上限依据：整表重置成功置 1，每次成功追加 +1。 */
+  const pagesLoaded = ref(0);
+
+  // solo 条目标记（photoId 集合）：见顶部「solo 机制」注。
+  const soloIds = reactive(new Set<string>());
+
+  let requestSequence = 0;
+
+  function fetchPage(cursor?: string): Promise<PublicPhotoList> {
+    return getPublicPhotos(inputs.token.value, {
+      locale: inputs.locale.value,
+      category: inputs.category.value ?? undefined,
+      cursor,
+    });
+  }
+
+  /** 页到达后的序列整合：natural（页序）在前、存活 solo 追加在后。
+   * 本页包含某 solo id 时先摘除其标记——该条目由本页副本在自然位置接管。 */
+  function integratePage(pageItems: PublicPhoto[], mode: 'reset' | 'append'): void {
+    // 快照须在摘标记前取：刚摘掉标记的旧 solo 条目不能被当作 natural 参与合并。
+    const previousNatural = photos.value.filter((photo) => !soloIds.has(photo.photoId));
+    for (const item of pageItems) soloIds.delete(item.photoId);
+    const natural =
+      mode === 'reset' ? [...pageItems] : mergeUniqueByPhotoId(previousNatural, pageItems);
+    const survivingSolos = photos.value.filter((photo) => soloIds.has(photo.photoId));
+    photos.value = [...natural, ...survivingSolos];
+  }
+
+  /** 整表重置加载（首载/分类切换/语言切换/token 切换/新照片提示刷新共用）。 */
+  async function resetAndLoad(): Promise<void> {
+    const sequence = ++requestSequence;
+    initialLoading.value = true;
+    initialErrorKey.value = null;
+    moreFailed.value = false;
+    loadingMore.value = false;
+    hasNew.value = false;
+    nextCursor.value = null;
+    hasMore.value = false;
+    try {
+      const page = await fetchPage();
+      if (sequence !== requestSequence) return;
+      integratePage(page.items, 'reset');
+      nextCursor.value = page.nextCursor;
+      hasMore.value = page.hasMore && page.nextCursor !== null;
+      pagesLoaded.value = 1;
+    } catch (error) {
+      if (sequence !== requestSequence) return;
+      const code = error instanceof ApiError ? error.code : NETWORK_ERROR_CODE;
+      initialErrorKey.value = errorMessageKey(code);
+    } finally {
+      if (sequence === requestSequence) initialLoading.value = false;
+    }
+  }
+
+  /** 取下一页追加（哨兵无限滚动 / 大图导航越过末尾 / 深链解析共用）；去重防御性
+   * 合并。并发调用（哨兵 + 大图预取/导航同时触发）共用同一在途请求，不重复取数。 */
+  let inflightMore: Promise<void> | null = null;
+
+  function loadMore(): Promise<void> {
+    if (initialLoading.value || initialErrorKey.value !== null) return Promise.resolve();
+    if (!hasMore.value || nextCursor.value === null) return Promise.resolve();
+    if (inflightMore !== null) return inflightMore;
+
+    const sequence = requestSequence;
+    const cursor = nextCursor.value;
+    if (cursor === null) return Promise.resolve();
+    loadingMore.value = true;
+    moreFailed.value = false;
+    inflightMore = (async () => {
+      try {
+        const page = await fetchPage(cursor);
+        if (sequence !== requestSequence) return;
+        integratePage(page.items, 'append');
+        nextCursor.value = page.nextCursor;
+        hasMore.value = page.hasMore && page.nextCursor !== null;
+        pagesLoaded.value += 1;
+      } catch {
+        if (sequence === requestSequence) moreFailed.value = true;
+      } finally {
+        if (sequence === requestSequence) loadingMore.value = false;
+        inflightMore = null;
+      }
+    })();
+    return inflightMore;
+  }
+
+  /** 新照片提示条点击：整表刷新回第 1 页并回顶（提示消失）。 */
+  async function refreshFromHint(): Promise<void> {
+    if (initialLoading.value) return;
+    await resetAndLoad();
+    window.scrollTo(0, 0);
+  }
+
+  function indexOf(photoId: string): number {
+    return photos.value.findIndex((photo) => photo.photoId === photoId);
+  }
+
+  /** 深链兜底：目标照片不在序列时以 solo 条目追加尾部；已存在则返回现有下标。 */
+  function ensureInSequence(photo: PublicPhoto): number {
+    const existing = indexOf(photo.photoId);
+    if (existing >= 0) return existing;
+    soloIds.add(photo.photoId);
+    photos.value = [...photos.value, photo];
+    return photos.value.length - 1;
+  }
+
+  function isSolo(photoId: string): boolean {
+    return soloIds.has(photoId);
+  }
+
+  /** 从序列移除（照片 404 下线后）。 */
+  function removePhoto(photoId: string): void {
+    soloIds.delete(photoId);
+    photos.value = photos.value.filter((photo) => photo.photoId !== photoId);
+  }
+
+  /** 单图刷新（Task 7 缩略图重试 / Task 8 大图签名过期共用）：成功原位换绑新
+   * 签名 URL；PHOTO_NOT_PUBLIC → 从序列移除（removed）；其他失败不动。 */
+  async function refreshPhotoUrls(photoId: string): Promise<PhotoRefreshResult> {
+    try {
+      const detail = await getPublicPhoto(inputs.token.value, photoId);
+      const photo = photos.value.find((item) => item.photoId === photoId);
+      if (photo !== undefined) {
+        photo.thumb = detail.thumb;
+        photo.browse = detail.browse;
+      }
+      return 'replaced';
+    } catch (error) {
+      if (error instanceof ApiError && error.code === 'PHOTO_NOT_PUBLIC') {
+        removePhoto(photoId);
+        return 'removed';
+      }
+      return 'failed';
+    }
+  }
+
+  // —— 新照片轮询（30s；e2e 可用 window.__viewerPollMs 覆盖；失败静默） ——
+
+  const DEFAULT_POLL_INTERVAL_MS = 30_000;
+
+  /** e2e/开发注入点：window.__viewerPollMs 覆盖轮询间隔（仅测试加速用）。 */
+  function pollIntervalMs(): number {
+    const override = (globalThis as { __viewerPollMs?: unknown }).__viewerPollMs;
+    return typeof override === 'number' && override > 0 ? override : DEFAULT_POLL_INTERVAL_MS;
+  }
+
+  let pollTimer: ReturnType<typeof setInterval> | undefined;
+
+  function stopPolling(): void {
+    if (pollTimer !== undefined) {
+      clearInterval(pollTimer);
+      pollTimer = undefined;
+    }
+  }
+
+  function startPolling(): void {
+    stopPolling();
+    pollTimer = setInterval(() => void pollOnce(), pollIntervalMs());
+  }
+
+  /** 取当前筛选的第 1 页对比 id 集合；发现新照片只亮提示条（不自动插入）。失败静默。 */
+  async function pollOnce(): Promise<void> {
+    if (document.hidden || initialLoading.value || initialErrorKey.value !== null || hasNew.value) {
+      return;
+    }
+    const sequence = requestSequence;
+    try {
+      const page = await fetchPage();
+      if (sequence !== requestSequence) return;
+      if (containsNewPhotoId(photos.value.map((photo) => photo.photoId), page.items)) {
+        hasNew.value = true;
+      }
+    } catch {
+      // 轮询失败静默：网络抖动不打扰观众（下一次间隔重试）。
+    }
+  }
+
+  function onVisibilityChange(): void {
+    if (document.hidden) stopPolling();
+    else startPolling();
+  }
+
+  onMounted(() => {
+    void resetAndLoad();
+    startPolling();
+    document.addEventListener('visibilitychange', onVisibilityChange);
+  });
+
+  onBeforeUnmount(() => {
+    stopPolling();
+    document.removeEventListener('visibilitychange', onVisibilityChange);
+  });
+
+  // token/语言/分类变化：整表重置（语言切换保留当前分类——inputs 自带）。
+  watch([inputs.token, inputs.locale, inputs.category], () => void resetAndLoad());
+
+  // reactive 包装：模板/脚本访问 sequence.photos 等 ref 自动解包（普通对象不会）。
+  return reactive({
+    photos,
+    nextCursor,
+    hasMore,
+    initialLoading,
+    initialErrorKey,
+    loadingMore,
+    moreFailed,
+    hasNew,
+    pagesLoaded,
+    resetAndLoad,
+    loadMore,
+    refreshFromHint,
+    indexOf,
+    ensureInSequence,
+    isSolo,
+    removePhoto,
+    refreshPhotoUrls,
+  });
+}
+
+export type PhotoSequence = ReturnType<typeof usePhotoSequence>;
diff --git a/apps/viewer/src/i18n/locales/en.ts b/apps/viewer/src/i18n/locales/en.ts
index ee73bed..4e67162 100644
--- a/apps/viewer/src/i18n/locales/en.ts
+++ b/apps/viewer/src/i18n/locales/en.ts
@@ -14,6 +14,18 @@ export default {
     retry: 'Retry',
   },
   lang: { switch: 'Switch language' },
+  viewer: {
+    title: 'Photo viewer',
+    close: 'Close',
+    previous: 'Previous photo',
+    next: 'Next photo',
+    counter: '{current} / {total}',
+    likeCount: '{count} likes',
+    loadFailed: 'Failed to load image',
+    // PHOTO_NOT_PUBLIC 专用：not found / unpublished / hidden share one code (anti-enumeration).
+    photoUnavailable: 'Photo not found or unavailable',
+    backToAlbum: 'Back to album',
+  },
   route: { tokenLabel: 'Album token', photoLabel: 'Photo' },
   errors: {
     albumNotFound: 'Album not found',
diff --git a/apps/viewer/src/i18n/locales/zh-CN.ts b/apps/viewer/src/i18n/locales/zh-CN.ts
index fd7e2b1..e5e01e9 100644
--- a/apps/viewer/src/i18n/locales/zh-CN.ts
+++ b/apps/viewer/src/i18n/locales/zh-CN.ts
@@ -14,6 +14,19 @@ export default {
     retry: '重试',
   },
   lang: { switch: '切换语言' },
+  viewer: {
+    title: '照片查看',
+    close: '关闭',
+    previous: '上一张',
+    next: '下一张',
+    counter: '{current} / {total}',
+    likeCount: '{count} 次点赞',
+    loadFailed: '图片加载失败',
+    photoRemoved: '照片已被移除',
+    // PHOTO_NOT_PUBLIC 专用：不存在/未发布/已隐藏同码（防枚举），文案覆盖两种成因。
+    photoUnavailable: '照片不存在或已下线',
+    backToAlbum: '返回相册',
+  },
   route: { tokenLabel: '相册令牌', photoLabel: '照片' },
   errors: {
     albumNotFound: '相册不存在',
diff --git a/apps/viewer/src/pages/ActivityPage.vue b/apps/viewer/src/pages/ActivityPage.vue
index c2de553..fbd37b6 100644
--- a/apps/viewer/src/pages/ActivityPage.vue
+++ b/apps/viewer/src/pages/ActivityPage.vue
@@ -1,23 +1,41 @@
 <script setup lang="ts">
-import { computed, onMounted, ref, watch, watchEffect } from 'vue';
+import { computed, onBeforeUnmount, onMounted, ref, watch, watchEffect } from 'vue';
 import { useI18n } from 'vue-i18n';
-import { useRoute } from 'vue-router';
-import { ApiError, NETWORK_ERROR_CODE, getPublicAlbum, type PublicAlbum } from '../api/client';
+import { useRoute, useRouter } from 'vue-router';
+import { ApiError, NETWORK_ERROR_CODE, getPublicAlbum, getPublicPhoto, type PublicAlbum } from '../api/client';
 import { errorMessageKey } from '../api/errors';
 import PhotoFeed from '../components/PhotoFeed.vue';
+import PhotoLightbox from '../components/PhotoLightbox.vue';
+import { usePhotoSequence } from '../feed/sequence';
 
-// 观众活动页（P1b Task 6）：信息区 + 空态 + 时区展示；瀑布流（Task 7）与大图
-// （Task 8，复用本组件于 /a/:token/p/:photoId 深链）随后补充。
+// 观众活动页（P1b Task 6 信息区 + Task 7 瀑布流 + Task 8 大图查看器）。
 //
 // 语言模型（文档化决策）：
 //   · UI 语言 = 用户选择（i18n locale，LocaleSwitcher 切换，localStorage 持久）；
 //   · 内容语言 = 同一选择值作为 ?locale= 查询参数传给公开端点；
 //   · resolvedLocale（响应）仅说明服务端实际返回的翻译语言（请求语言缺翻译时
 //     回退 defaultLocale）——不反向驱动 UI 语言，避免「切了英文却被拽回中文」。
+//
+// 大图查看器编排（Task 8）：
+//   · 序列状态（分页/游标/轮询）在本页创建一次（usePhotoSequence），PhotoFeed 与
+//     PhotoLightbox 共享——大图左右切换保持列表浏览序列，越过末尾自动扩展下一页；
+//   · 当前照片以 photoId（v-model）为键，序列重排（深链 solo 归位/条目移除）时
+//     指向自动保持；
+//   · 深链 /a/:token/p/:photoId：先取单图立即开大图（序列在背后继续加载），
+//     目标不在已加载序列时以 solo 条目兜底入尾，最多再拉 DEEP_LINK_PAGE_CAP 页
+//     寻找自然位置（文档化折中：防深链老照片触发全量翻页；超限保留 solo）；
+//   · URL 同步：点击打开 = push 深链路由；大图内切换/回退邻居 = replace（不产生
+//     多余历史条目）；关闭 = push 过则 history.back()（浏览器后退同理关闭），
+//     深链直达（非本会话 push）则 replace 回相册路由；
+//   · 关闭回位：打开时记录 window.scrollY，关闭（含浏览器后退触发）恢复——
+//     瀑布流为绝对定位布局，列表未被触碰，恢复即精确回位。
+
 const route = useRoute();
+const router = useRouter();
 const { t, locale } = useI18n();
 
 const token = computed(() => String(route.params.token ?? ''));
+const routePhotoId = computed(() => (route.params.photoId === undefined ? null : String(route.params.photoId)));
 
 const album = ref<PublicAlbum | null>(null);
 const loadErrorKey = ref<string | null>(null);
@@ -95,12 +113,170 @@ const venueText = computed(() => {
 });
 
 // 分类筛选（Task 7）：id 级持有（语言切换只换名称，选中态跨语言保留——
-// PhotoFeed 收到同一 category 值不重置，locale 变化才整表重取）。
+// 同一 category 值不重置，locale 变化才整表重取）。
 const selectedCategory = ref<string | null>(null);
 
 function selectCategory(categoryId: string | null): void {
   selectedCategory.value = categoryId;
 }
+
+// —— 照片序列（Task 8 提升：feed + lightbox 共享） ——
+
+const sequence = usePhotoSequence({ token, locale, category: selectedCategory });
+
+// —— 大图查看器（Task 8） ——
+
+/** 深链解析的翻页上限（含首页）：超过后目标照片保留 solo 条目（见文件头注）。 */
+const DEEP_LINK_PAGE_CAP = 3;
+
+const lightboxPhotoId = ref<string | null>(null);
+/** 深链目标 404（PHOTO_NOT_PUBLIC）：页内本地化提示 + 返回相册链接。 */
+const deepLinkNotFound = ref(false);
+/** 深链单图请求失败（网络等）：本地化提示 + 重试。 */
+const deepLinkErrorKey = ref<string | null>(null);
+/** 照片经刷新确认下线：轻提示（role=status，数秒后自动消失）。 */
+const photoRemovedNotice = ref(false);
+let removedNoticeTimer: ReturnType<typeof setTimeout> | undefined;
+
+let savedScrollY = 0;
+/** 本会话内点击 push 过深链路由 → 关闭走 history.back()；深链直达则 replace。 */
+let pushedByUs = false;
+/** 深链解析竞态令牌：仅最新一次解析可落地。 */
+let resolveSequence = 0;
+/** 最近一次大图就位（打开或深链解析）所属 token：识别「路由目标=自己 push 的」。 */
+let resolvedToken = '';
+
+const currentPhoto = computed(() => {
+  if (lightboxPhotoId.value === null) return null;
+  return sequence.photos.find((photo) => photo.photoId === lightboxPhotoId.value) ?? null;
+});
+
+function showRemovedNotice(): void {
+  photoRemovedNotice.value = true;
+  if (removedNoticeTimer !== undefined) clearTimeout(removedNoticeTimer);
+  removedNoticeTimer = setTimeout(() => {
+    photoRemovedNotice.value = false;
+  }, 4000);
+}
+
+/** 瀑布流单元格点击 → 打开大图：记录滚动锚点并 push 深链路由。 */
+async function openFromFeed(photoId: string): Promise<void> {
+  savedScrollY = window.scrollY;
+  pushedByUs = true;
+  resolvedToken = token.value;
+  // 先就位再 push：routePhotoId watcher 看到路由目标与当前照片一致即跳过，
+  // 避免自触发深链重解析（会冲掉 pushedByUs 并造成开-关闪烁）。
+  lightboxPhotoId.value = photoId;
+  await router.push({ name: 'activity-photo', params: { token: token.value, photoId } });
+}
+
+/** 关闭大图：恢复滚动锚点；push 过 → back()（历史出栈），深链直达 → replace 回相册。 */
+function closeLightbox(): void {
+  if (lightboxPhotoId.value === null) return;
+  lightboxPhotoId.value = null;
+  deepLinkNotFound.value = false;
+  deepLinkErrorKey.value = null;
+  window.scrollTo(0, savedScrollY);
+  if (pushedByUs) {
+    pushedByUs = false;
+    router.back();
+  } else if (route.name === 'activity-photo') {
+    void router.replace({ name: 'activity', params: { token: token.value } });
+  }
+}
+
+/** 深链/前进导航进入照片路由：先取单图立即开大图，再由相邻页 watcher 构成序列。 */
+async function openFromRoute(photoId: string): Promise<void> {
+  const run = ++resolveSequence;
+  resolvedToken = token.value;
+  deepLinkNotFound.value = false;
+  deepLinkErrorKey.value = null;
+  savedScrollY = window.scrollY;
+  pushedByUs = false;
+  lightboxPhotoId.value = null;
+
+  let detail: Awaited<ReturnType<typeof getPublicPhoto>>;
+  try {
+    detail = await getPublicPhoto(token.value, photoId);
+  } catch (error) {
+    if (run !== resolveSequence) return;
+    if (error instanceof ApiError && error.code === 'PHOTO_NOT_PUBLIC') {
+      deepLinkNotFound.value = true;
+      return;
+    }
+    deepLinkErrorKey.value = error instanceof ApiError ? errorMessageKey(error.code) : errorMessageKey(NETWORK_ERROR_CODE);
+    return;
+  }
+  if (run !== resolveSequence) return;
+  // 序列已含该照片（首页先到）→ 直接就位；否则 solo 兜底入尾（可立即查看/切换）。
+  if (sequence.indexOf(photoId) === -1) sequence.ensureInSequence(detail);
+  lightboxPhotoId.value = photoId;
+}
+
+// 深链入口（immediate 覆盖首挂；token 变化时对同 photoId 重新解析）。
+// 自己 push/replace 造成的路由变化（目标与当前照片一致且同 token）不重解析。
+watch(
+  [routePhotoId, token],
+  () => {
+    const photoId = routePhotoId.value;
+    if (photoId === null) return;
+    if (photoId === lightboxPhotoId.value && token.value === resolvedToken) return;
+    void openFromRoute(photoId);
+  },
+  { immediate: true },
+);
+
+// 深链相邻页：目标仍是 solo 且未达翻页上限 → 追拉下一页，直到自然位置出现
+//（integratePage 自动以页内副本取代 solo）或上限/游标耗尽（保留 solo，文档化）。
+watch(
+  () => [sequence.photos, sequence.initialLoading, sequence.initialErrorKey, sequence.hasMore, lightboxPhotoId.value] as const,
+  () => {
+    const photoId = lightboxPhotoId.value;
+    if (photoId === null) return;
+    if (!sequence.isSolo(photoId)) return;
+    if (sequence.initialLoading || sequence.initialErrorKey !== null) return;
+    if (sequence.pagesLoaded >= DEEP_LINK_PAGE_CAP || !sequence.hasMore || sequence.loadingMore) return;
+    void sequence.loadMore();
+  },
+);
+
+// 大图内切换/邻居回退 → replace 深链路由（不产生多余历史条目）。
+watch(lightboxPhotoId, (photoId) => {
+  if (photoId === null) return;
+  if (route.name !== 'activity-photo' || routePhotoId.value === photoId) return;
+  void router.replace({ name: 'activity-photo', params: { token: token.value, photoId } });
+});
+
+// 浏览器后退/前进离开照片路由：同步关闭大图（不再动历史），恢复滚动锚点。
+watch(
+  () => route.name,
+  (name) => {
+    if (name !== 'activity') return;
+    if (lightboxPhotoId.value !== null) {
+      lightboxPhotoId.value = null;
+      pushedByUs = false;
+      window.scrollTo(0, savedScrollY);
+    }
+    deepLinkNotFound.value = false;
+    deepLinkErrorKey.value = null;
+  },
+);
+
+/** 大图确认照片下线（404 刷新）：从序列移除，回退到原位邻居（或关闭），轻提示。 */
+function onPhotoRemoved(photoId: string, neighborIndex: number): void {
+  showRemovedNotice();
+  if (lightboxPhotoId.value !== photoId) return;
+  const fallback = sequence.photos[Math.min(neighborIndex, sequence.photos.length - 1)];
+  if (fallback === undefined) {
+    closeLightbox();
+  } else {
+    lightboxPhotoId.value = fallback.photoId;
+  }
+}
+
+onBeforeUnmount(() => {
+  if (removedNoticeTimer !== undefined) clearTimeout(removedNoticeTimer);
+});
 </script>
 
 <template>
@@ -119,7 +295,7 @@ function selectCategory(categoryId: string | null): void {
         :src="album.banner.url"
         :alt="album.translation.title"
         @error="bannerFailed = true"
-      />
+      >
 
       <header class="info">
         <h1 class="title">{{ album.translation.title }}</h1>
@@ -136,6 +312,17 @@ function selectCategory(categoryId: string | null): void {
         </dl>
       </header>
 
+      <!-- 深链目标不可见（404 防枚举同码）：页内本地化提示 + 返回相册。 -->
+      <div v-if="deepLinkNotFound || deepLinkErrorKey !== null" class="deep-link-notice" role="alert">
+        <p>{{ deepLinkNotFound ? t('viewer.photoUnavailable') : t(deepLinkErrorKey ?? 'errors.unknown') }}</p>
+        <div class="notice-actions">
+          <RouterLink :to="{ name: 'activity', params: { token } }">{{ t('viewer.backToAlbum') }}</RouterLink>
+          <button v-if="deepLinkErrorKey !== null" type="button" @click="routePhotoId !== null && openFromRoute(routePhotoId)">
+            {{ t('album.retry') }}
+          </button>
+        </div>
+      </div>
+
       <!-- 分类筛选 chips：全部 + 各分类；选中态高亮（aria-pressed）。 -->
       <nav v-if="album.categories.length > 0" class="categories" :aria-label="t('album.categories')">
         <button
@@ -160,10 +347,22 @@ function selectCategory(categoryId: string | null): void {
         </button>
       </nav>
 
-      <!-- 瀑布流（Task 7）：懒加载/无限滚动/轮询提示在 PhotoFeed 内实现。 -->
-      <PhotoFeed :token="token" :locale="locale" :category="selectedCategory" />
+      <!-- 瀑布流（Task 7）：序列数据在 PhotoSequence（Task 8 共享给大图）。 -->
+      <PhotoFeed :sequence="sequence" @open="openFromFeed" />
       <!-- viewCount 契约占位 null：不渲染任何浏览计数节点。 -->
     </template>
+
+    <!-- 大图查看器（Task 8）：当前照片以 photoId 键控（v-model）。 -->
+    <PhotoLightbox
+      v-if="lightboxPhotoId !== null && currentPhoto !== null"
+      v-model:photo-id="lightboxPhotoId"
+      :sequence="sequence"
+      @removed="onPhotoRemoved"
+      @close="closeLightbox"
+    />
+
+    <!-- 照片下线轻提示（大图内 404 刷新确认移除时）。 -->
+    <p v-if="photoRemovedNotice" class="removed-notice" role="status">{{ t('viewer.photoRemoved') }}</p>
   </section>
 </template>
 
@@ -238,4 +437,42 @@ function selectCategory(categoryId: string | null): void {
   background: #eff6ff;
   color: #1d4ed8;
 }
+.deep-link-notice {
+  border: 1px solid #fde68a;
+  border-radius: 8px;
+  background: #fffbeb;
+  padding: 12px 16px;
+  margin-bottom: 16px;
+  color: #92400e;
+}
+.deep-link-notice p {
+  margin: 0 0 8px;
+}
+.notice-actions {
+  display: flex;
+  gap: 12px;
+  align-items: center;
+}
+.notice-actions a {
+  color: #1d4ed8;
+}
+.notice-actions button {
+  border: 1px solid #d1d5db;
+  border-radius: 6px;
+  background: #fff;
+  padding: 4px 12px;
+  cursor: pointer;
+}
+.removed-notice {
+  position: fixed;
+  bottom: 24px;
+  left: 50%;
+  transform: translateX(-50%);
+  margin: 0;
+  z-index: 110;
+  border-radius: 8px;
+  background: rgba(17, 24, 39, 0.9);
+  color: #f9fafb;
+  padding: 8px 16px;
+}
 </style>
diff --git a/apps/viewer/src/viewer/zoom.ts b/apps/viewer/src/viewer/zoom.ts
new file mode 100644
index 0000000..75b4528
--- /dev/null
+++ b/apps/viewer/src/viewer/zoom.ts
@@ -0,0 +1,53 @@
+// apps/viewer/src/viewer/zoom.ts —— 大图查看器（Task 8）缩放/平移纯状态机：
+// 无 DOM 依赖的数学层，供 PhotoLightbox 以 PointerEvent/wheel 驱动、vitest 直接覆盖。
+//
+// 模型：图片经 CSS `translate(tx,ty) scale(s)`（transform-origin 居中）渲染，
+// 图片上距中心 (px,py) 的点落在屏幕 (px*s+tx, py*s+ty)（相对中心）。据此：
+//   · zoomAt：以 (cx,cy)（相对图片中心）为不动点缩放——该点缩放前后屏幕位置不变，
+//     反解 t' = t + c*(s-s')；
+//   · scale 钳制 [MIN_SCALE, MAX_SCALE]；回到 1 时平移归零（复位对齐居中）；
+//   · panBy 仅在 scale>1 生效（scale=1 无可平移的溢出边）。
+
+export interface ZoomState {
+  scale: number;
+  tx: number;
+  ty: number;
+}
+
+export const MIN_SCALE = 1;
+export const MAX_SCALE = 4;
+
+export const INITIAL_ZOOM: ZoomState = { scale: MIN_SCALE, tx: 0, ty: 0 };
+
+export function clampScale(scale: number): number {
+  return Math.min(MAX_SCALE, Math.max(MIN_SCALE, scale));
+}
+
+/** 复位（双击/双触/切换照片时）。 */
+export function resetZoom(): ZoomState {
+  return { ...INITIAL_ZOOM };
+}
+
+/** 以 (cx,cy) 为不动点缩放 factor 倍（>1 放大）；钳制后返回新状态（不修改入参）。 */
+export function zoomAt(state: ZoomState, factor: number, cx: number, cy: number): ZoomState {
+  const scale = clampScale(state.scale * factor);
+  if (scale === state.scale) return state;
+  if (scale === MIN_SCALE) return resetZoom();
+  return {
+    scale,
+    tx: state.tx + cx * (state.scale - scale),
+    ty: state.ty + cy * (state.scale - scale),
+  };
+}
+
+/** 按指针位移平移；scale=1 时为无操作（无可平移空间）。 */
+export function panBy(state: ZoomState, dx: number, dy: number): ZoomState {
+  if (state.scale <= MIN_SCALE) return state;
+  return { scale: state.scale, tx: state.tx + dx, ty: state.ty + dy };
+}
+
+/** wheel 事件 → 缩放因子：deltaY<0（上滚/外张）放大；指数映射让手感均匀。 */
+export function wheelFactor(deltaY: number): number {
+  const WHEEL_SENSITIVITY = 0.0022;
+  return Math.exp(-deltaY * WHEEL_SENSITIVITY);
+}