diff --git a/apps/viewer/e2e/album.spec.ts b/apps/viewer/e2e/album.spec.ts
index aa88ede..7d96bb5 100644
--- a/apps/viewer/e2e/album.spec.ts
+++ b/apps/viewer/e2e/album.spec.ts
@@ -48,9 +48,9 @@ test('renders album info in zh with timezone-adjusted time, chips and empty stat
   await expect(page.locator('.meta')).toContainText('大宴会厅 · 上海市浦东新区世纪大道 100 号');
 
   const chips = page.locator('.chip');
-  await expect(chips).toHaveCount(2);
-  await expect(chips.first()).toBeDisabled();
-  await expect(chips).toHaveText(['签到墙', '开场']);
+  await expect(chips).toHaveCount(3); // Task 7 起：全部 + 各分类（可点选）
+  await expect(chips.first()).toBeEnabled();
+  await expect(chips).toHaveText(['全部', '签到墙', '开场']);
 
   await expect(page.locator('.empty-notice')).toHaveText('照片即将上线');
   // 该相册无 banner 资产 → 不渲染图。
diff --git a/apps/viewer/e2e/feed.spec.ts b/apps/viewer/e2e/feed.spec.ts
new file mode 100644
index 0000000..dabecd4
--- /dev/null
+++ b/apps/viewer/e2e/feed.spec.ts
@@ -0,0 +1,132 @@
+import { expect, test, type Page } from '@playwright/test';
+import { cleanupSeededAlbums, seedAlbum, seedCategory, seedPhoto } from './helpers';
+
+// Task 7 瀑布流 Playwright（真实后端）：35 张已发布照片（公开列表默认页 30）→
+// 初始 30 + 滚动取第 2 页 5 张；分类 chips 过滤；新照片轮询提示（__viewerPollMs
+// 注入缩短间隔，见 PhotoFeed pollIntervalMs 的 dev/test 覆盖钩子）。
+
+test.afterAll(async () => {
+  await cleanupSeededAlbums();
+});
+
+/** 5 种宽高比例轮换（瀑布流高度预留的真实形状输入）。 */
+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 },
+];
+
+const TOTAL = 35; // 30（第 1 页）+ 5（第 2 页）
+
+/** 种「瀑布流相册」：2 分类 + 35 张已发布照片（前 20 张 catA、后 15 张 catB；
+ * publishedAt 逐张递减 60s 保证列表顺序确定）。 */
+async function seedFeedAlbum(alias: string): Promise<{ albumId: string; token: string }> {
+  const album = await seedAlbum({
+    alias,
+    translations: [{ locale: 'zh-CN', title: '瀑布流测试相册' }],
+  });
+  const catA = await seedCategory(album.id, 0, [{ locale: 'zh-CN', name: '签到墙' }]);
+  const catB = await seedCategory(album.id, 1, [{ locale: 'zh-CN', name: '开场' }]);
+  const base = Date.now();
+  for (let i = 0; i < TOTAL; i++) {
+    const ratio = RATIOS[i % RATIOS.length]!;
+    await seedPhoto(album.id, `${alias}-p${i}`, {
+      categoryId: i < 20 ? catA : catB,
+      width: ratio.width,
+      height: ratio.height,
+      publishedAt: new Date(base - (i + 1) * 60_000),
+    });
+  }
+  return { albumId: album.id, token: album.publicToken };
+}
+
+/** 反复滚到底直至游标耗尽（end-note 出现）或循环上限。 */
+async function scrollToLoadAll(page: Page): Promise<void> {
+  for (let i = 0; i < 15; i++) {
+    if ((await page.locator('.end-note').count()) > 0) return;
+    await page.evaluate(() => window.scrollTo(0, document.body.scrollHeight));
+    await page.waitForTimeout(400);
+  }
+}
+
+test('scroll loads both pages until exhausted and thumbs decode', async ({ page }) => {
+  test.setTimeout(90_000);
+  const { token } = await seedFeedAlbum('scroll');
+  await page.addInitScript(() => localStorage.setItem('viewer.locale', 'zh-CN'));
+  await page.goto(`/a/${token}`);
+
+  // 第 1 页 30 张 + 哨兵在位（hasMore）。
+  await expect(page.locator('.cell')).toHaveCount(30);
+  await expect(page.locator('.sentinel')).toHaveCount(1);
+
+  // 懒加载：首屏缩略图经签名 URL 取回真实字节（解码成功 naturalWidth > 0）。
+  await expect
+    .poll(async () =>
+      page.locator('img.cell-img').first().evaluate((img) => (img as HTMLImageElement).naturalWidth),
+    )
+    .toBeGreaterThan(0);
+
+  await scrollToLoadAll(page);
+
+  // 第 2 页 5 张追加，游标耗尽 → 哨兵卸载、底部提示出现。
+  await expect(page.locator('.cell')).toHaveCount(35);
+  await expect(page.locator('.end-note')).toHaveText('已经到底了');
+  await expect(page.locator('.sentinel')).toHaveCount(0);
+});
+
+test('category chips filter the feed; All restores pagination', async ({ page }) => {
+  test.setTimeout(90_000);
+  const { token } = await seedFeedAlbum('filter');
+  await page.addInitScript(() => localStorage.setItem('viewer.locale', 'zh-CN'));
+  await page.goto(`/a/${token}`);
+  await expect(page.locator('.cell')).toHaveCount(30);
+
+  await page.getByRole('button', { name: '签到墙' }).click();
+  await expect(page.locator('.cell')).toHaveCount(20);
+  await expect(page.locator('.end-note')).toBeVisible(); // 20 ≤ 30 单页即尽
+
+  await page.getByRole('button', { name: '开场' }).click();
+  await expect(page.locator('.cell')).toHaveCount(15);
+
+  await page.getByRole('button', { name: '全部' }).click();
+  await expect(page.locator('.cell')).toHaveCount(30);
+  await scrollToLoadAll(page);
+  await expect(page.locator('.cell')).toHaveCount(35);
+});
+
+test('new-photo poll hint appears; click refreshes to include new photos', async ({ page }) => {
+  test.setTimeout(90_000);
+  const { albumId, token } = await seedFeedAlbum('poll');
+  await page.addInitScript(() => {
+    localStorage.setItem('viewer.locale', 'zh-CN');
+    (window as unknown as { __viewerPollMs?: number }).__viewerPollMs = 500;
+  });
+  await page.goto(`/a/${token}`);
+  await expect(page.locator('.cell')).toHaveCount(30);
+  await scrollToLoadAll(page);
+  await expect(page.locator('.cell')).toHaveCount(35);
+  await expect(page.locator('.new-photo-bar')).toHaveCount(0);
+
+  // 轮询期间直种 2 张更新的照片（publishedAt 晚于全部既有）。
+  const base = Date.now();
+  for (let i = 0; i < 2; i++) {
+    await seedPhoto(albumId, `poll-new-${i}`, {
+      categoryId: null,
+      width: 480,
+      height: 300,
+      publishedAt: new Date(base + (i + 1) * 60_000),
+    });
+  }
+
+  // 提示条出现（不自动插入——仍 35 张）。
+  await expect(page.locator('.new-photo-bar')).toBeVisible({ timeout: 10_000 });
+  await expect(page.locator('.cell')).toHaveCount(35);
+
+  // 点击 → 整表刷新回第 1 页（含新照片），滚动后 37 张。
+  await page.locator('.new-photo-bar').click();
+  await expect(page.locator('.new-photo-bar')).toHaveCount(0);
+  await scrollToLoadAll(page);
+  await expect(page.locator('.cell')).toHaveCount(37);
+});
diff --git a/apps/viewer/e2e/helpers.ts b/apps/viewer/e2e/helpers.ts
index e3da25f..d27d71e 100644
--- a/apps/viewer/e2e/helpers.ts
+++ b/apps/viewer/e2e/helpers.ts
@@ -1,10 +1,13 @@
 // apps/viewer/e2e/helpers.ts —— Playwright 夹具：真实后端直种（决策见计划 Task 6
 // Step 2：真实 API + compose 基础设施，fixture 走 Prisma/Storage 直种，镜像
 // services/api/test/public.e2e-spec.ts 的种子形状）。公开端点匿名可达，无需登录态。
+// Task 7 起补 seedPhoto：直种「已发布完成态」照片（photos + thumb/browse 变体行
+// + MinIO 真实 JPEG 对象，行形状同 worker 发布事务落库形态）。
 import { randomBytes } from 'node:crypto';
 import { join } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { config } from 'dotenv';
+import sharp from 'sharp';
 import { PrismaClient } from '@photo/db-cn';
 import { createStorageFromEnv, type MinioStorageAdapter } from '@photo/storage';
 
@@ -108,13 +111,111 @@ export async function seedBannerAsset(albumId: string): Promise<void> {
   });
 }
 
+/** 测试内生成真实 JPEG（sharp，同 services/api test 约定；尺寸小控制体积/耗时）。 */
+async function makeJpeg(width: number, height: number): Promise<Buffer> {
+  return sharp({
+    create: { width, height, channels: 3, background: { r: 96, g: 130, b: 182 } },
+  })
+    .jpeg({ quality: 70 })
+    .toBuffer();
+}
+
+/** cuid 形状 ID（对象键含 photoId，须先有 ID 再一次 insert 成形，同 api 约定）。 */
+function cuidLike(alias: string): string {
+  return `c${Date.now().toString(36)}${alias}${randomBytes(6).toString('hex')}`;
+}
+
+/** 与 worker publish.service variantsObjectKey 同布局的变体键。 */
+function variantKey(albumId: string, photoId: string, variant: 'thumb' | 'browse'): string {
+  return `${KEY_ROOT}/albums/${albumId}/variants/${photoId}/1/${variant}.jpg`;
+}
+
+export interface SeedPhotoOptions {
+  categoryId?: string | null;
+  /** browse 宽高（驱动列表占位与瀑布流比例；thumb 减半生成）。 */
+  width?: number;
+  height?: number;
+  publishedAt: Date;
+}
+
+/** 直种已发布照片：photos 行（ready/published，entityVersion=2 对齐发布事务）+
+ * thumb/browse 变体行 + MinIO 真实对象。publishedAt 必传（列表排序确定性）。 */
+export async function seedPhoto(
+  albumId: string,
+  alias: string,
+  options: SeedPhotoOptions,
+): Promise<string> {
+  const photoId = cuidLike(alias);
+  const width = options.width ?? 480;
+  const height = options.height ?? 300;
+  const thumbWidth = Math.max(1, Math.round(width / 2));
+  const thumbHeight = Math.max(1, Math.round(height / 2));
+  const [thumb, browse] = await Promise.all([
+    makeJpeg(thumbWidth, thumbHeight),
+    makeJpeg(width, height),
+  ]);
+  await storage.put(variantKey(albumId, photoId, 'thumb'), thumb, 'image/jpeg');
+  await storage.put(variantKey(albumId, photoId, 'browse'), browse, 'image/jpeg');
+  await prisma.photos.create({
+    data: {
+      id: photoId,
+      albumId,
+      uploaderId: `u-viewer-e2e-${alias}`,
+      categoryId: options.categoryId ?? null,
+      objectKey: `${KEY_ROOT}/albums/${albumId}/originals/${photoId}.jpg`,
+      bytes: browse.length,
+      width,
+      height,
+      uploadedAt: options.publishedAt,
+      publishedAt: options.publishedAt,
+      processingState: 'ready',
+      visibility: 'published',
+      entityVersion: 2,
+    },
+  });
+  await prisma.photo_variants.createMany({
+    data: [
+      {
+        photoId,
+        variant: 'thumb',
+        objectKey: variantKey(albumId, photoId, 'thumb'),
+        bytes: thumb.length,
+        version: 1,
+        width: thumbWidth,
+        height: thumbHeight,
+      },
+      {
+        photoId,
+        variant: 'browse',
+        objectKey: variantKey(albumId, photoId, 'browse'),
+        bytes: browse.length,
+        version: 1,
+        width,
+        height,
+      },
+    ],
+  });
+  return 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）。
+ * 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）。
  * MinIO 对象不在此删：services/api e2e 的 reset 会整体清 `photo-live/dev` 前缀，
  * dev 桶内残余有界（同 api e2e 约定）。 */
 export async function cleanupSeededAlbums(): Promise<void> {
   try {
     if (seededAlbumIds.length > 0) {
+      const photos = await prisma.photos.findMany({
+        where: { albumId: { in: seededAlbumIds } },
+        select: { id: true },
+      });
+      if (photos.length > 0) {
+        await prisma.photo_variants.deleteMany({
+          where: { photoId: { in: photos.map((p) => p.id) } },
+        });
+      }
+      await prisma.photos.deleteMany({ where: { albumId: { in: seededAlbumIds } } });
       const categories = await prisma.categories.findMany({
         where: { albumId: { in: seededAlbumIds } },
         select: { id: true },
diff --git a/apps/viewer/package.json b/apps/viewer/package.json
index 5c04701..a10b3d4 100644
--- a/apps/viewer/package.json
+++ b/apps/viewer/package.json
@@ -27,6 +27,7 @@
     "@vue/test-utils": "^2.4.6",
     "dotenv": "^16.4.5",
     "jsdom": "^25.0.0",
+    "sharp": "^0.35.0",
     "typescript": "^5.6.0",
     "vite": "~5.4.0",
     "vitest": "^2.1.0",
diff --git a/apps/viewer/src/__tests__/activity.spec.ts b/apps/viewer/src/__tests__/activity.spec.ts
index c009229..9e99e03 100644
--- a/apps/viewer/src/__tests__/activity.spec.ts
+++ b/apps/viewer/src/__tests__/activity.spec.ts
@@ -8,11 +8,16 @@ import ActivityPage from '../pages/ActivityPage.vue';
 import { router } from '../router';
 import { makeAlbum, makeEnAlbum } from './fixtures';
 
-// ActivityPage（Task 6）组件测试：api client 以真实模块为底、仅替身 getPublicAlbum，
+// ActivityPage（Task 6）组件测试：api client 以真实模块为底、仅替身 getPublicAlbum /
+// getPublicPhotos（Task 7 起活动页内嵌 PhotoFeed，需喂空页避免真实 fetch），
 // 保证 ApiError/errors 映射等真实逻辑参与断言。
 vi.mock('../api/client', async (importOriginal) => {
   const actual = await importOriginal<typeof import('../api/client')>();
-  return { ...actual, getPublicAlbum: vi.fn() };
+  return {
+    ...actual,
+    getPublicAlbum: vi.fn(),
+    getPublicPhotos: vi.fn().mockResolvedValue({ items: [], nextCursor: null, hasMore: false }),
+  };
 });
 
 const mockedGetPublicAlbum = vi.mocked(getPublicAlbum);
@@ -63,8 +68,8 @@ describe('activity page (Task 6)', () => {
     expect(wrapper.find('.meta').text()).toContain('10月1日');
 
     const chips = wrapper.findAll('.chip');
-    expect(chips.map((chip) => chip.text())).toEqual(['签到墙', '开场']);
-    expect(chips.every((chip) => chip.attributes('disabled') !== undefined)).toBe(true);
+    expect(chips.map((chip) => chip.text())).toEqual(['全部', '签到墙', '开场']);
+    expect(chips.every((chip) => chip.attributes('disabled') === undefined)).toBe(true);
 
     expect(wrapper.find('.empty-notice').text()).toBe('照片即将上线');
     // 无 banner 资产 → 不渲染 img；viewCount 占位 null → 不渲染任何计数节点。
diff --git a/apps/viewer/src/__tests__/feed-layout.spec.ts b/apps/viewer/src/__tests__/feed-layout.spec.ts
new file mode 100644
index 0000000..b08edfd
--- /dev/null
+++ b/apps/viewer/src/__tests__/feed-layout.spec.ts
@@ -0,0 +1,91 @@
+import { describe, expect, it } from 'vitest';
+import {
+  containsNewPhotoId,
+  layoutWaterfall,
+  mergeUniqueByPhotoId,
+} from '../feed/layout';
+
+// Task 7 瀑布流纯函数层：列放置/高度预留/去重/新照片判定（组件行为在 feed.spec）。
+// 数字断言手算依据：containerWidth 320、gap 8、双列 → columnWidth = floor(312/2) = 156。
+
+describe('layoutWaterfall (pure placement)', () => {
+  it('places each item in the shorter column with aspect-preserved height', () => {
+    const layout = layoutWaterfall(
+      [
+        { width: 200, height: 100 }, // A: ratio .5 → 78
+        { width: 100, height: 200 }, // B: ratio 2 → 312
+        { width: 156, height: 156 }, // C: ratio 1 → 156
+        { width: 300, height: 100 }, // D: ratio 1/3 → 52
+      ],
+      320,
+    );
+
+    expect(layout.columnWidth).toBe(156);
+    // A→col0（空列同高取索引小）；B→col1（0 < 86）；C→col0（86 < 320）；D→col0（250 < 320）。
+    expect(layout.placements.map((p) => p.column)).toEqual([0, 1, 0, 0]);
+    expect(layout.placements.map((p) => p.top)).toEqual([0, 0, 86, 250]);
+    expect(layout.placements.map((p) => p.height)).toEqual([78, 312, 156, 52]);
+    // 最高列 320 去掉末尾间距 → 容器高 312。
+    expect(layout.height).toBe(312);
+  });
+
+  it('computes column left offsets with the gap and alternates on equal heights', () => {
+    const layout = layoutWaterfall(
+      [
+        { width: 100, height: 100 },
+        { width: 100, height: 100 },
+        { width: 100, height: 100 },
+      ],
+      320,
+    );
+
+    expect(layout.placements.map((p) => p.left)).toEqual([0, 164, 0]);
+    expect(layout.placements.map((p) => p.column)).toEqual([0, 1, 0]);
+    expect(layout.placements.map((p) => p.top)).toEqual([0, 0, 164]);
+    // col0 累计 156+8+156+8=328，col1 156+8=164 → 容器高 328-8=320。
+    expect(layout.height).toBe(320);
+  });
+
+  it('falls back to a square placeholder for degenerate dimensions (no NaN)', () => {
+    const layout = layoutWaterfall([{ width: 0, height: 500 }, { width: 400, height: 0 }], 320);
+    expect(layout.placements.map((p) => p.height)).toEqual([156, 156]);
+    expect(layout.placements.every((p) => Number.isFinite(p.top) && Number.isFinite(p.left))).toBe(true);
+  });
+
+  it('returns an empty layout for no items and tolerates zero container width', () => {
+    const empty = layoutWaterfall([], 320);
+    expect(empty.placements).toEqual([]);
+    expect(empty.height).toBe(0);
+
+    const zero = layoutWaterfall([{ width: 100, height: 100 }], 0);
+    expect(zero.columnWidth).toBe(0);
+    expect(zero.placements.map((p) => p.height)).toEqual([1]);
+  });
+});
+
+describe('mergeUniqueByPhotoId (page append dedupe)', () => {
+  it('appends only unseen photoIds and preserves order', () => {
+    const merged = mergeUniqueByPhotoId(
+      [{ photoId: 'a' }, { photoId: 'b' }],
+      [{ photoId: 'b' }, { photoId: 'c' }, { photoId: 'a' }, { photoId: 'c' }],
+    );
+    expect(merged.map((item) => item.photoId)).toEqual(['a', 'b', 'c']);
+  });
+
+  it('keeps the existing entry when a duplicate id arrives', () => {
+    const existing = [{ photoId: 'a', width: 1 }];
+    const merged = mergeUniqueByPhotoId(existing, [{ photoId: 'a', width: 2 }]);
+    expect(merged).toHaveLength(1);
+    expect(merged[0].width).toBe(1);
+  });
+});
+
+describe('containsNewPhotoId (poll detection)', () => {
+  it('detects ids outside the known set and returns false when all known', () => {
+    expect(containsNewPhotoId(['a', 'b'], [{ photoId: 'b' }, { photoId: 'c' }])).toBe(true);
+    expect(containsNewPhotoId(['a', 'b'], [{ photoId: 'b' }, { photoId: 'a' }])).toBe(false);
+    // 已知集为空（空相册）时任何已发布照片都是「新照片」。
+    expect(containsNewPhotoId([], [{ photoId: 'a' }])).toBe(true);
+    expect(containsNewPhotoId(['a'], [])).toBe(false);
+  });
+});
diff --git a/apps/viewer/src/__tests__/feed.spec.ts b/apps/viewer/src/__tests__/feed.spec.ts
new file mode 100644
index 0000000..1f9a8b0
--- /dev/null
+++ b/apps/viewer/src/__tests__/feed.spec.ts
@@ -0,0 +1,380 @@
+import { flushPromises, mount, type VueWrapper } from '@vue/test-utils';
+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 PhotoFeed from '../components/PhotoFeed.vue';
+
+// 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。
+
+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);
+
+/** 可控 IO 假件：记录实例与 init（rootMargin 区分懒加载 400px / 哨兵 600px）。 */
+class FakeIntersectionObserver {
+  static instances: FakeIntersectionObserver[] = [];
+  readonly root: Element | Document | null = null;
+  readonly thresholds: ReadonlyArray<number> = [];
+  private readonly targets = new Set<Element>();
+
+  constructor(
+    readonly callback: IntersectionObserverCallback,
+    readonly init: IntersectionObserverInit = {},
+  ) {
+    FakeIntersectionObserver.instances.push(this);
+  }
+
+  get rootMargin(): string {
+    return typeof this.init.rootMargin === 'string' ? this.init.rootMargin : '';
+  }
+
+  get observed(): Element[] {
+    return [...this.targets];
+  }
+
+  observe(target: Element): void {
+    this.targets.add(target);
+  }
+
+  unobserve(target: Element): void {
+    this.targets.delete(target);
+  }
+
+  disconnect(): void {
+    this.targets.clear();
+  }
+
+  takeRecords(): IntersectionObserverEntry[] {
+    return [];
+  }
+
+  trigger(targets: Element[], isIntersecting: boolean): void {
+    this.callback(
+      targets.map((target) => ({ target, isIntersecting }) as IntersectionObserverEntry),
+      this as unknown as IntersectionObserver,
+    );
+  }
+}
+
+class FakeResizeObserver {
+  observe(): void {}
+  unobserve(): void {}
+  disconnect(): void {}
+}
+
+function lazyObserver(): FakeIntersectionObserver {
+  const observer = FakeIntersectionObserver.instances.find((instance) =>
+    instance.rootMargin.includes('400px'),
+  );
+  if (observer === undefined) throw new Error('lazy observer not created');
+  return observer;
+}
+
+function sentinelObserver(): FakeIntersectionObserver {
+  const observer = FakeIntersectionObserver.instances.find((instance) =>
+    instance.rootMargin.includes('600px'),
+  );
+  if (observer === undefined) throw new Error('sentinel observer not created');
+  return observer;
+}
+
+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 };
+}
+
+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,
+    },
+  });
+  mounted.push(wrapper);
+  return wrapper;
+}
+
+describe('photo feed (Task 7)', () => {
+  beforeEach(() => {
+    localStorage.clear();
+    i18n = createViewerI18n('zh-CN');
+    FakeIntersectionObserver.instances = [];
+    vi.stubGlobal('IntersectionObserver', FakeIntersectionObserver);
+    vi.stubGlobal('ResizeObserver', FakeResizeObserver);
+    // jsdom 无布局：clientWidth 恒 0 → 原型 getter mock 为 700（columnWidth=346）。
+    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'), makePhoto('p3')], 'cur-1'));
+    mockedGetPublicPhoto.mockReset();
+  });
+
+  afterEach(() => {
+    while (mounted.length > 0) {
+      mounted.pop()?.unmount();
+    }
+    vi.unstubAllGlobals();
+    vi.restoreAllMocks();
+    vi.useRealTimers();
+  });
+
+  it('renders first page as absolute-positioned cells with reserved heights', async () => {
+    const wrapper = mountFeed();
+    await flushPromises();
+
+    expect(mockedGetPublicPhotos).toHaveBeenCalledWith('tok-feed', { locale: 'zh-CN' });
+    const cells = wrapper.findAll('.cell');
+    expect(cells).toHaveLength(3);
+    // 700 容器宽 → columnWidth 346；800x500 比例 → 条高 round(346*.625)=216。
+    // 3 条：col0 [224,0] → p2 入 col1 → p3 入 col0（top 224）→ 容器高 224+216=440。
+    expect(wrapper.find('.waterfall').attributes('style')).toContain('height: 440px');
+    expect(cells[1].attributes('style')).toContain('left: 354px');
+    expect(cells[2].attributes('style')).toContain('top: 224px');
+  });
+
+  it('binds img src only after the cell approaches the viewport (lazy swap)', async () => {
+    const wrapper = mountFeed();
+    await flushPromises();
+
+    expect(wrapper.findAll('img.cell-img')).toHaveLength(0);
+    const cells = wrapper.findAll('.cell');
+    expect(lazyObserver().observed).toHaveLength(3);
+
+    lazyObserver().trigger([cells[0].element, cells[1].element], true);
+    await vi.waitFor(() => expect(wrapper.findAll('img.cell-img')).toHaveLength(2));
+    expect(wrapper.find('img.cell-img').attributes('src')).toBe('http://img.test/p1-thumb.jpg?s=1');
+    // 已显示的单元格不再被观察。
+    expect(lazyObserver().observed).toHaveLength(1);
+  });
+
+  it('loads the next page when the sentinel intersects, dedupes and stops at exhaustion', async () => {
+    const wrapper = mountFeed();
+    await flushPromises();
+
+    const sentinel = wrapper.find('.sentinel');
+    expect(sentinel.exists()).toBe(true);
+    // 第 2 页带回重复的 p3（游标边界漂移防御）→ 仅追加新 id。
+    mockedGetPublicPhotos.mockResolvedValueOnce(makeList([makePhoto('p3'), makePhoto('p4')], null));
+
+    sentinelObserver().trigger([sentinel.element], true);
+    await flushPromises();
+
+    expect(mockedGetPublicPhotos).toHaveBeenLastCalledWith(
+      'tok-feed',
+      expect.objectContaining({ cursor: 'cur-1' }),
+    );
+    expect(wrapper.findAll('.cell')).toHaveLength(4);
+    // 游标耗尽：哨兵卸载 + 底部提示。
+    expect(wrapper.find('.sentinel').exists()).toBe(false);
+    expect(wrapper.find('.end-note').text()).toBe('已经到底了');
+    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();
+    await flushPromises();
+
+    expect(wrapper.find('.empty-notice').text()).toBe('照片即将上线');
+    expect(wrapper.find('.cell').exists()).toBe(false);
+  });
+
+  it('initial load failure shows the localized error with retry; retry recovers', async () => {
+    mockedGetPublicPhotos
+      .mockRejectedValueOnce(new ApiError('NETWORK_ERROR', 'network down', 0, null))
+      .mockResolvedValueOnce(makeList([makePhoto('p1')], null));
+    const wrapper = mountFeed();
+    await flushPromises();
+
+    expect(wrapper.find('.error[role="alert"]').text()).toContain('网络连接失败');
+    expect(wrapper.find('.cell').exists()).toBe(false);
+
+    await wrapper.find('.error button').trigger('click');
+    await flushPromises();
+    expect(wrapper.findAll('.cell')).toHaveLength(1);
+  });
+
+  it('retries a failed thumb once with a refreshed signed URL, then hides the img', async () => {
+    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));
+
+    mockedGetPublicPhoto.mockResolvedValue({
+      ...makePhoto('p1'),
+      categoryId: null,
+      thumb: { url: 'http://img.test/p1-thumb.jpg?s=2', expiresAt: '2026-10-01T01:00:00.000Z' },
+    });
+    await wrapper.findAll('img.cell-img')[0].trigger('error');
+    await flushPromises();
+
+    expect(mockedGetPublicPhoto).toHaveBeenCalledWith('tok-feed', 'p1');
+    expect(wrapper.findAll('img.cell-img')[0].attributes('src')).toBe('http://img.test/p1-thumb.jpg?s=2');
+
+    // 第二次失败 → 收起该图（占位底色仍在，布局不塌）。
+    await wrapper.findAll('img.cell-img')[0].trigger('error');
+    await flushPromises();
+    expect(wrapper.findAll('img.cell-img')).toHaveLength(2);
+    expect(wrapper.findAll('.cell')).toHaveLength(3);
+    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__/routing.spec.ts b/apps/viewer/src/__tests__/routing.spec.ts
index 361f08b..b62805d 100644
--- a/apps/viewer/src/__tests__/routing.spec.ts
+++ b/apps/viewer/src/__tests__/routing.spec.ts
@@ -8,9 +8,14 @@ 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）。
 vi.mock('../api/client', async (importOriginal) => {
   const actual = await importOriginal<typeof import('../api/client')>();
-  return { ...actual, getPublicAlbum: vi.fn() };
+  return {
+    ...actual,
+    getPublicAlbum: vi.fn(),
+    getPublicPhotos: vi.fn().mockResolvedValue({ items: [], nextCursor: null, hasMore: false }),
+  };
 });
 
 const mockedGetPublicAlbum = vi.mocked(getPublicAlbum);
diff --git a/apps/viewer/src/api/client.ts b/apps/viewer/src/api/client.ts
index ba7a733..e1ad526 100644
--- a/apps/viewer/src/api/client.ts
+++ b/apps/viewer/src/api/client.ts
@@ -2,6 +2,7 @@ import type { components } from '@photo/contracts';
 
 // 契约生成类型直连（Vite 原生 ESM，无需 mapper）
 export type PublicAlbum = components['schemas']['PublicAlbum'];
+export type PublicPhoto = components['schemas']['PublicPhoto'];
 export type PublicPhotoList = components['schemas']['PublicPhotoList'];
 export type PublicPhotoDetail = components['schemas']['PublicPhotoDetail'];
 
diff --git a/apps/viewer/src/components/PhotoFeed.vue b/apps/viewer/src/components/PhotoFeed.vue
new file mode 100644
index 0000000..a9d7907
--- /dev/null
+++ b/apps/viewer/src/components/PhotoFeed.vue
@@ -0,0 +1,432 @@
+<script setup lang="ts">
+import { computed, onBeforeUnmount, onMounted, 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';
+
+// 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。
+//
+// 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）。
+
+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;
+}>();
+
+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);
+
+// 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);
+const sentinelEl = ref<HTMLElement | null>(null);
+const containerWidth = ref(0);
+
+const layout = computed(() => layoutWaterfall(photos.value, containerWidth.value));
+
+let resizeObserver: ResizeObserver | null = null;
+
+function measureContainer(): void {
+  if (trackEl.value !== null) containerWidth.value = trackEl.value.clientWidth;
+}
+
+watch(
+  trackEl,
+  (el) => {
+    resizeObserver?.disconnect();
+    resizeObserver = null;
+    if (el === null) return;
+    measureContainer();
+    if (typeof ResizeObserver !== 'undefined') {
+      resizeObserver = new ResizeObserver(measureContainer);
+      resizeObserver.observe(el);
+    }
+  },
+  { flush: 'post' },
+);
+
+// —— 懒加载/哨兵 IntersectionObserver ——
+
+const cellElements = new Map<Element, string>();
+let lazyObserver: IntersectionObserver | null = null;
+let sentinelObserver: IntersectionObserver | null = null;
+
+function ensureLazyObserver(): IntersectionObserver | null {
+  if (lazyObserver !== null) return lazyObserver;
+  if (typeof IntersectionObserver === 'undefined') return null;
+  lazyObserver = new IntersectionObserver(
+    (entries) => {
+      for (const entry of entries) {
+        if (!entry.isIntersecting) continue;
+        const photoId = cellElements.get(entry.target);
+        if (photoId !== undefined) shownIds.add(photoId);
+        lazyObserver?.unobserve(entry.target);
+      }
+    },
+    { rootMargin: '400px 0px' },
+  );
+  return lazyObserver;
+}
+
+/** v-for 函数 ref：登记 el → photoId 并纳入懒观察；IO 不可用退化立即显示。
+ * 按下标取 photos（卸载时 ref 收到 null 先行返回——函数 ref 在整表替换后
+ * 会对旧 vnode 重算，此时闭包里的数组访问必须可空）。 */
+function registerCell(el: unknown, index: number): void {
+  if (!(el instanceof HTMLElement)) return;
+  const photo = photos.value[index];
+  if (photo === undefined) return;
+  cellElements.set(el, photo.photoId);
+  if (shownIds.has(photo.photoId)) return;
+  const observer = ensureLazyObserver();
+  if (observer === null) {
+    shownIds.add(photo.photoId);
+    return;
+  }
+  observer.observe(el);
+}
+
+/** 移除已脱离文档的单元格映射（整表替换后 DOM 销毁的 el 不再可达）。 */
+function pruneCellElements(): void {
+  for (const [el] of cellElements) {
+    if (!el.isConnected) cellElements.delete(el);
+  }
+}
+
+watch(
+  sentinelEl,
+  (el) => {
+    sentinelObserver?.disconnect();
+    sentinelObserver = null;
+    if (el === null) return;
+    sentinelObserver = new IntersectionObserver(
+      (entries) => {
+        if (entries.some((entry) => entry.isIntersecting)) void loadMore();
+      },
+      { rootMargin: '600px 0px' },
+    );
+    sentinelObserver.observe(el);
+  },
+  { 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。 */
+async function onImgError(photo: PublicPhoto): Promise<void> {
+  const { photoId } = photo;
+  if (failedIds.has(photoId)) return;
+  if (retriedIds.has(photoId)) {
+    failedIds.add(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);
+  }
+}
+
+// —— 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">
+      {{ t('album.newPhotos') }}
+    </button>
+
+    <p v-if="initialLoading" class="status">{{ t('album.loading') }}</p>
+
+    <div v-else-if="initialErrorKey !== null" class="error" role="alert">
+      <p>{{ t(initialErrorKey) }}</p>
+      <button type="button" @click="resetAndLoad">{{ t('album.retry') }}</button>
+    </div>
+
+    <div v-else-if="photos.length === 0" class="feed">
+      <p class="empty-notice">{{ t('album.emptyNotice') }}</p>
+    </div>
+
+    <template v-else>
+      <div ref="trackEl" class="waterfall" :style="{ height: `${layout.height}px` }">
+        <div
+          v-for="placement in layout.placements"
+          :key="photos[placement.index].photoId"
+          :ref="(el) => registerCell(el, placement.index)"
+          class="cell"
+          :style="{
+            left: `${placement.left}px`,
+            top: `${placement.top}px`,
+            width: `${layout.columnWidth}px`,
+            height: `${placement.height}px`,
+          }"
+        >
+          <img
+            v-if="shownIds.has(photos[placement.index].photoId) && !failedIds.has(photos[placement.index].photoId)"
+            class="cell-img"
+            :src="photos[placement.index].thumb.url"
+            :alt="`${t('route.photoLabel')} ${placement.index + 1}`"
+            loading="lazy"
+            decoding="async"
+            @error="onImgError(photos[placement.index])"
+          >
+        </div>
+      </div>
+
+      <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>
+      </div>
+      <p v-else-if="!hasMore" class="end-note">{{ t('album.end') }}</p>
+
+      <div v-if="hasMore" ref="sentinelEl" class="sentinel" aria-hidden="true" />
+    </template>
+  </div>
+</template>
+
+<style scoped>
+/* 极简基线样式：视觉打磨留待 P4a。 */
+.photo-feed {
+  position: relative;
+}
+.new-photo-bar {
+  position: sticky;
+  top: 0;
+  z-index: 1;
+  display: block;
+  width: 100%;
+  margin-bottom: 12px;
+  border: 1px solid #1d4ed8;
+  border-radius: 8px;
+  background: #eff6ff;
+  color: #1d4ed8;
+  padding: 8px 12px;
+  font-size: 0.875rem;
+  cursor: pointer;
+}
+.status {
+  color: #6b7280;
+}
+.more-status {
+  text-align: center;
+  padding: 8px 0;
+}
+.error {
+  color: #b91c1c;
+}
+.error button,
+.more-failed button {
+  margin-top: 8px;
+  border: 1px solid #d1d5db;
+  border-radius: 6px;
+  background: #fff;
+  padding: 4px 12px;
+  cursor: pointer;
+}
+.more-failed {
+  text-align: center;
+}
+.feed {
+  border: 1px dashed #e5e7eb;
+  border-radius: 8px;
+  padding: 48px 16px;
+  text-align: center;
+}
+.empty-notice {
+  margin: 0;
+  color: #9ca3af;
+}
+.waterfall {
+  position: relative;
+}
+.cell {
+  position: absolute;
+  border-radius: 6px;
+  overflow: hidden;
+  background: linear-gradient(160deg, #f3f4f6, #e5e7eb);
+}
+.cell-img {
+  display: block;
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+}
+.end-note {
+  text-align: center;
+  color: #9ca3af;
+  font-size: 0.875rem;
+  padding: 12px 0;
+  margin: 0;
+}
+.sentinel {
+  height: 1px;
+}
+</style>
diff --git a/apps/viewer/src/feed/layout.ts b/apps/viewer/src/feed/layout.ts
new file mode 100644
index 0000000..f740afe
--- /dev/null
+++ b/apps/viewer/src/feed/layout.ts
@@ -0,0 +1,102 @@
+// apps/viewer/src/feed/layout.ts —— 瀑布流纯函数层（Task 7）：双列绝对定位布局
+// 与列表纯数据操作。抽出为无 DOM 依赖的模块以便 vitest 直接覆盖放置/去重逻辑。
+//
+// 布局模型（选型见计划 Task 7 Step 1：绝对定位而非 CSS columns——滚动位置可
+// 恢复、条目高按 width/height 比例预留）：
+//   · 列宽 = (容器宽 - (列数-1)*列间距) / 列数，向下取整；
+//   · 条目高 = round(列宽 * height/width)（宽高来自 browse 变体，服务端必返）；
+//     宽高非正的脏数据回退正方形容高（不产生 NaN/0 塌陷）；
+//   · 放置规则：总是放入当前「最矮」列，同高取索引小者（确定性输出）；
+//   · 容器高 = 最高列去掉末尾间距（间距只在条目之间生效）。
+
+/** 布局输入：仅需宽高（PublicPhoto 满足）。 */
+export interface WaterfallSource {
+  width: number;
+  height: number;
+}
+
+/** 单条放置结果：index 对应输入数组下标，left/top/height 为像素值。 */
+export interface WaterfallPlacement {
+  index: number;
+  column: number;
+  left: number;
+  top: number;
+  height: number;
+}
+
+export interface WaterfallLayout {
+  placements: WaterfallPlacement[];
+  /** 单列宽度（所有列等宽）。 */
+  columnWidth: number;
+  /** 容器内容总高（px）。 */
+  height: number;
+}
+
+export const WATERFALL_COLUMNS = 2;
+export const WATERFALL_GAP = 8;
+
+/**
+ * 双列（可推广 N 列）瀑布流布局：逐条放入最矮列。O(n) 全量重算——分页追加
+ * 也整体重算（n 为已加载条数，P1 量级下开销可忽略），换来 resize/刷新的确定性。
+ */
+export function layoutWaterfall(
+  items: readonly WaterfallSource[],
+  containerWidth: number,
+  options: { columns?: number; gap?: number } = {},
+): WaterfallLayout {
+  const columns = Math.max(1, options.columns ?? WATERFALL_COLUMNS);
+  const gap = Math.max(0, options.gap ?? WATERFALL_GAP);
+  const columnWidth =
+    containerWidth > 0
+      ? Math.floor((containerWidth - gap * (columns - 1)) / columns)
+      : 0;
+
+  const columnHeights = new Array<number>(columns).fill(0);
+  const placements: WaterfallPlacement[] = [];
+
+  items.forEach((item, index) => {
+    const ratio =
+      item.width > 0 && item.height > 0 ? item.height / item.width : 1;
+    const height = Math.max(1, Math.round(columnWidth * ratio));
+    let column = 0;
+    for (let c = 1; c < columns; c += 1) {
+      if (columnHeights[c] < columnHeights[column]) column = c;
+    }
+    placements.push({
+      index,
+      column,
+      left: column * (columnWidth + gap),
+      top: columnHeights[column],
+      height,
+    });
+    columnHeights[column] += height + gap;
+  });
+
+  const height =
+    placements.length > 0 ? Math.max(...columnHeights) - gap : 0;
+  return { placements, columnWidth, height };
+}
+
+/** 追加分页结果时按 photoId 去重（防御：游标边界漂移、轮询与分页竞争）。 */
+export function mergeUniqueByPhotoId<T extends { photoId: string }>(
+  existing: readonly T[],
+  incoming: readonly T[],
+): T[] {
+  const seen = new Set(existing.map((item) => item.photoId));
+  const merged = [...existing];
+  for (const item of incoming) {
+    if (seen.has(item.photoId)) continue;
+    seen.add(item.photoId);
+    merged.push(item);
+  }
+  return merged;
+}
+
+/** 轮询判定：incoming 中是否存在 known 集合之外的新照片。 */
+export function containsNewPhotoId(
+  knownIds: Iterable<string>,
+  incoming: readonly { photoId: string }[],
+): boolean {
+  const known = new Set(knownIds);
+  return incoming.some((item) => !known.has(item.photoId));
+}
diff --git a/apps/viewer/src/i18n/locales/en.ts b/apps/viewer/src/i18n/locales/en.ts
index 6622d11..ee73bed 100644
--- a/apps/viewer/src/i18n/locales/en.ts
+++ b/apps/viewer/src/i18n/locales/en.ts
@@ -3,10 +3,14 @@ export default {
   home: { hint: 'Open an album link to start viewing' },
   album: {
     loading: 'Loading…',
+    loadingMore: 'Loading more…',
     emptyNotice: 'Photos coming soon',
     time: 'Time',
     venue: 'Venue',
     categories: 'Categories',
+    all: 'All',
+    end: 'You have reached the end',
+    newPhotos: 'New photos — tap to refresh',
     retry: 'Retry',
   },
   lang: { switch: 'Switch language' },
diff --git a/apps/viewer/src/i18n/locales/zh-CN.ts b/apps/viewer/src/i18n/locales/zh-CN.ts
index 0a423ef..fd7e2b1 100644
--- a/apps/viewer/src/i18n/locales/zh-CN.ts
+++ b/apps/viewer/src/i18n/locales/zh-CN.ts
@@ -3,10 +3,14 @@ export default {
   home: { hint: '打开相册链接即可观看' },
   album: {
     loading: '加载中…',
+    loadingMore: '加载更多…',
     emptyNotice: '照片即将上线',
     time: '时间',
     venue: '地点',
     categories: '分类',
+    all: '全部',
+    end: '已经到底了',
+    newPhotos: '有新照片，点击查看',
     retry: '重试',
   },
   lang: { switch: '切换语言' },
diff --git a/apps/viewer/src/pages/ActivityPage.vue b/apps/viewer/src/pages/ActivityPage.vue
index f6265c4..c2de553 100644
--- a/apps/viewer/src/pages/ActivityPage.vue
+++ b/apps/viewer/src/pages/ActivityPage.vue
@@ -4,6 +4,7 @@ import { useI18n } from 'vue-i18n';
 import { useRoute } from 'vue-router';
 import { ApiError, NETWORK_ERROR_CODE, getPublicAlbum, type PublicAlbum } from '../api/client';
 import { errorMessageKey } from '../api/errors';
+import PhotoFeed from '../components/PhotoFeed.vue';
 
 // 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。
@@ -92,6 +93,14 @@ const venueText = computed(() => {
     .filter((part): part is string => part !== null)
     .join(' · ');
 });
+
+// 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）。
+const selectedCategory = ref<string | null>(null);
+
+function selectCategory(categoryId: string | null): void {
+  selectedCategory.value = categoryId;
+}
 </script>
 
 <template>
@@ -127,17 +136,32 @@ const venueText = computed(() => {
         </dl>
       </header>
 
-      <!-- Task 7 接线分类过滤；当前仅展示（禁用态占位）。 -->
+      <!-- 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 v-for="category in album.categories" :key="category.id" type="button" class="chip" disabled>
+        <button
+          type="button"
+          class="chip"
+          :class="{ active: selectedCategory === null }"
+          :aria-pressed="selectedCategory === null"
+          @click="selectCategory(null)"
+        >
+          {{ t('album.all') }}
+        </button>
+        <button
+          v-for="category in album.categories"
+          :key="category.id"
+          type="button"
+          class="chip"
+          :class="{ active: selectedCategory === category.id }"
+          :aria-pressed="selectedCategory === category.id"
+          @click="selectCategory(category.id)"
+        >
           {{ category.name }}
         </button>
       </nav>
 
-      <!-- 瀑布流（Task 7）前的列表占位：空态文案由 i18n 提供。 -->
-      <div class="feed">
-        <p class="empty-notice">{{ t('album.emptyNotice') }}</p>
-      </div>
+      <!-- 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" />
       <!-- viewCount 契约占位 null：不渲染任何浏览计数节点。 -->
     </template>
   </section>
@@ -207,18 +231,11 @@ const venueText = computed(() => {
   color: #374151;
   padding: 2px 12px;
   font-size: 0.875rem;
+  cursor: pointer;
 }
-.chip:disabled {
-  cursor: default;
-}
-.feed {
-  border: 1px dashed #e5e7eb;
-  border-radius: 8px;
-  padding: 48px 16px;
-  text-align: center;
-}
-.empty-notice {
-  margin: 0;
-  color: #9ca3af;
+.chip.active {
+  border-color: #1d4ed8;
+  background: #eff6ff;
+  color: #1d4ed8;
 }
 </style>
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index bfea9e3..a8b2173 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -72,6 +72,9 @@ importers:
       jsdom:
         specifier: ^25.0.0
         version: 25.0.1
+      sharp:
+        specifier: ^0.35.0
+        version: 0.35.4(@types/node@22.20.3)
       typescript:
         specifier: ^5.6.0
         version: 5.9.3