diff --git a/services/api/src/albums/albums.module.ts b/services/api/src/albums/albums.module.ts
index d8378df..b7b885d 100644
--- a/services/api/src/albums/albums.module.ts
+++ b/services/api/src/albums/albums.module.ts
@@ -1,15 +1,20 @@
-// services/api/src/albums/albums.module.ts —— 相册模块（Task 14 起步，Task 15 补全）。
-// PermissionsService（A02 权限基石）+ AlbumsService/AlbumsController（创建/详情/
-// 列表；Task 16 增补 PATCH）。export PermissionsService 供 uploads/photos 等后续
-// 模块经模块间 DI 复用同一份判定逻辑；AlbumsService 暂无外部消费者不 export。
+// services/api/src/albums/albums.module.ts —— 相册模块（Task 14 起步，Task 15
+// 补全，Task 16 增补 PATCH，Task 17 增补成员/分类）。PermissionsService（A02
+// 权限基石）+ AlbumsService/MembersService/CategoriesService 与对应控制器。
+// export PermissionsService 供 uploads/photos 等后续模块经模块间 DI 复用同一
+// 份判定逻辑；AlbumsService 等暂无外部消费者不 export。
 import { Module } from '@nestjs/common';
 import { AlbumsController } from './albums.controller';
 import { AlbumsService } from './albums.service';
+import { CategoriesController } from './categories.controller';
+import { CategoriesService } from './categories.service';
+import { MembersController } from './members.controller';
+import { MembersService } from './members.service';
 import { PermissionsService } from './permissions.service';
 
 @Module({
-  controllers: [AlbumsController],
-  providers: [PermissionsService, AlbumsService],
+  controllers: [AlbumsController, MembersController, CategoriesController],
+  providers: [PermissionsService, AlbumsService, MembersService, CategoriesService],
   exports: [PermissionsService],
 })
 export class AlbumsModule {}
diff --git a/services/api/src/albums/albums.service.ts b/services/api/src/albums/albums.service.ts
index 4b7365d..64f5d1d 100644
--- a/services/api/src/albums/albums.service.ts
+++ b/services/api/src/albums/albums.service.ts
@@ -1,6 +1,6 @@
-// services/api/src/albums/albums.service.ts —— 相册创建/详情/列表核心逻辑（Task 15）。
-// 契约权威：packages/contracts/openapi.yaml tags [albums]（createAlbum/getAlbum/
-// listAlbums；updateAlbum 属 Task 16）。要点：
+// services/api/src/albums/albums.service.ts —— 相册创建/详情/更新/列表核心逻辑
+// （Task 15；update 自 Task 16）。契约权威：packages/contracts/openapi.yaml
+// tags [albums]（createAlbum/getAlbum/updateAlbum/listAlbums）。要点：
 //   · 创建走单事务：albums + album_translations（批量）+ album_members(owner)
 //     + audit_logs(album.create)——四表要么全成要么全无，杜绝「无主相册」
 //     （权限全部源自成员行，Task 14 结论：漏写 owner 行会让创建者自己不可见）。
@@ -29,6 +29,12 @@ import {
 } from '../shared/cursor';
 import type { AlbumCreateRequestDto, AlbumUpdateRequestDto } from './dto';
 import { PermissionsService } from './permissions.service';
+import {
+  albumForbidden,
+  albumNotFound,
+  isUniqueViolationOn,
+  validationFailed,
+} from './support';
 
 export type AlbumTranslationResponse =
   components['schemas']['AlbumTranslation'];
@@ -69,32 +75,6 @@ function generatePublicToken(): string {
   return token;
 }
 
-function albumNotFound(): ApiException {
-  return new ApiException(
-    ErrorCodes.ALBUM_NOT_FOUND,
-    '相册不存在或不可见',
-    HttpStatus.NOT_FOUND,
-  );
-}
-
-/** P2002 是否命中指定唯一索引（meta.target 形如 ['publicToken']）。 */
-function isUniqueViolationOn(err: unknown, field: string): boolean {
-  if (typeof err !== 'object' || err === null) {
-    return false;
-  }
-  const { code, meta } = err as { code?: unknown; meta?: { target?: unknown } };
-  if (code !== 'P2002') {
-    return false;
-  }
-  const target = meta?.target;
-  const fields = Array.isArray(target)
-    ? target
-    : typeof target === 'string'
-      ? [target]
-      : [];
-  return fields.includes(field);
-}
-
 type AlbumRow = Prisma.albumsGetPayload<Prisma.albumsDefaultArgs>;
 type AlbumTranslationRow = Prisma.album_translationsGetPayload<
   Prisma.album_translationsDefaultArgs
@@ -146,7 +126,8 @@ export class AlbumsService {
 
   /**
    * 创建相册：事务内四写（albums/translations/members/audit），返回完整
-   * Album 形状（categories 恒 []——分类自 Task 17 起才有写入入口）。
+   * Album 形状（categories 恒 []——新建相册尚无分类，写入入口在
+   * CategoriesService，Task 17）。
    */
   async create(
     userId: string,
@@ -156,11 +137,7 @@ export class AlbumsService {
     // ——那是 500 而非 400，必须在入事务前以校验错误拒绝。
     const locales = dto.translations.map((t) => t.locale);
     if (new Set(locales).size !== locales.length) {
-      throw new ApiException(
-        ErrorCodes.VALIDATION_FAILED,
-        'translations 存在重复 locale',
-        HttpStatus.BAD_REQUEST,
-      );
+      throw validationFailed('translations 存在重复 locale');
     }
 
     let albumId: string;
@@ -274,11 +251,7 @@ export class AlbumsService {
       (key) => dto[key] !== undefined,
     ) as string[];
     if (fields.length === 0) {
-      throw new ApiException(
-        ErrorCodes.VALIDATION_FAILED,
-        '请求体至少需要包含一个待更新字段',
-        HttpStatus.BAD_REQUEST,
-      );
+      throw validationFailed('请求体至少需要包含一个待更新字段');
     }
     if (dto.translations !== undefined) {
       // 同 create：重复 locale 会在事务内 createMany 撞唯一索引变 500，先 400。
@@ -296,11 +269,7 @@ export class AlbumsService {
       throw albumNotFound();
     }
     if (!(await this.permissions.canManageAlbum(user, albumId))) {
-      throw new ApiException(
-        ErrorCodes.AUTH_FORBIDDEN,
-        '仅创建者或管理员可修改相册',
-        HttpStatus.FORBIDDEN,
-      );
+      throw albumForbidden('仅创建者或管理员可修改相册');
     }
 
     await this.prisma.$transaction(async (tx) => {
@@ -318,21 +287,15 @@ export class AlbumsService {
             ? null
             : new Date(dto.endAt);
       if (endAt !== null && endAt.getTime() <= startAt.getTime()) {
-        throw new ApiException(
-          ErrorCodes.VALIDATION_FAILED,
-          'endAt 必须晚于 startAt',
-          HttpStatus.BAD_REQUEST,
-        );
+        throw validationFailed('endAt 必须晚于 startAt');
       }
 
       // 合并校验②：合并后的 defaultLocale 必须被合并后的翻译集覆盖。
       const defaultLocale = dto.defaultLocale ?? album.defaultLocale;
       if (dto.translations !== undefined) {
         if (!dto.translations.some((t) => t.locale === defaultLocale)) {
-          throw new ApiException(
-            ErrorCodes.VALIDATION_FAILED,
+          throw validationFailed(
             'translations 必须包含（更新后的）defaultLocale 对应语言的条目',
-            HttpStatus.BAD_REQUEST,
           );
         }
       } else if (dto.defaultLocale !== undefined) {
@@ -342,11 +305,7 @@ export class AlbumsService {
           select: { locale: true },
         });
         if (!rows.some((r) => r.locale === defaultLocale)) {
-          throw new ApiException(
-            ErrorCodes.VALIDATION_FAILED,
-            'defaultLocale 必须有对应翻译条目',
-            HttpStatus.BAD_REQUEST,
-          );
+          throw validationFailed('defaultLocale 必须有对应翻译条目');
         }
       }
 
@@ -474,8 +433,8 @@ export class AlbumsService {
 
   /**
    * 组装完整 Album 形状：主行 + 翻译（locale 升序，确定性输出）+ 分类
-   * （sortOrder 升序，Task 17 前无写入入口故实际为空数组——join 逻辑先就位，
-   * 分类上线即生效）。相册域无 Prisma relation，全部二次查询应用层组装。
+   * （sortOrder 升序；写入入口为 CategoriesService，Task 17 起）。相册域无
+   * Prisma relation，全部二次查询应用层组装。
    */
   private async loadAlbum(albumId: string): Promise<AlbumResponse | null> {
     const album = await this.prisma.albums.findUnique({
diff --git a/services/api/src/albums/categories.controller.ts b/services/api/src/albums/categories.controller.ts
new file mode 100644
index 0000000..ffb7106
--- /dev/null
+++ b/services/api/src/albums/categories.controller.ts
@@ -0,0 +1,58 @@
+// services/api/src/albums/categories.controller.ts —— 分类端点（Task 17）。
+// 方法名与契约 operationId 一一对应（createCategory/updateCategory/
+// deleteCategory）。契约把创建挂在 /albums/{albumId}/categories、更新/删除
+// 挂在 /categories/{categoryId}——单控制器 + 显式全路径（两个基地址）。
+// 控制器级 SessionGuard：三端点全需认证；权限与 HTTP 映射（404/403/400）
+// 由 CategoriesService 抛 ApiException。
+import {
+  Body,
+  Controller,
+  Delete,
+  HttpCode,
+  HttpStatus,
+  Param,
+  Patch,
+  Post,
+  Req,
+  UseGuards,
+} from '@nestjs/common';
+import { AuthenticatedRequest, SessionGuard } from '../auth/session.guard';
+import { userOf } from './albums.controller';
+import { CategoriesService, type CategoryResponse } from './categories.service';
+import {
+  CategoryCreateRequestDto,
+  CategoryUpdateRequestDto,
+} from './dto';
+
+@Controller()
+@UseGuards(SessionGuard)
+export class CategoriesController {
+  constructor(private readonly categoriesService: CategoriesService) {}
+
+  @Post('albums/:albumId/categories')
+  createCategory(
+    @Param('albumId') albumId: string,
+    @Body() dto: CategoryCreateRequestDto,
+    @Req() req: AuthenticatedRequest,
+  ): Promise<CategoryResponse> {
+    return this.categoriesService.create(userOf(req), albumId, dto);
+  }
+
+  @Patch('categories/:categoryId')
+  updateCategory(
+    @Param('categoryId') categoryId: string,
+    @Body() dto: CategoryUpdateRequestDto,
+    @Req() req: AuthenticatedRequest,
+  ): Promise<CategoryResponse> {
+    return this.categoriesService.update(userOf(req), categoryId, dto);
+  }
+
+  @Delete('categories/:categoryId')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  deleteCategory(
+    @Param('categoryId') categoryId: string,
+    @Req() req: AuthenticatedRequest,
+  ): Promise<void> {
+    return this.categoriesService.remove(userOf(req), categoryId);
+  }
+}
diff --git a/services/api/src/albums/categories.service.ts b/services/api/src/albums/categories.service.ts
new file mode 100644
index 0000000..c15c483
--- /dev/null
+++ b/services/api/src/albums/categories.service.ts
@@ -0,0 +1,249 @@
+// services/api/src/albums/categories.service.ts —— 相册分类管理（Task 17）。
+// 契约权威：openapi.yaml tags [categories]（createCategory/updateCategory/
+// deleteCategory）。要点：
+//   · /categories/{categoryId} 端点的 404 语义与契约一致：分类不存在或所属
+//     相册不可见统一 ALBUM_NOT_FOUND（先读分类行→404，再 canView→404、
+//     canManage→403；非成员视角「分类不存在」与「不可见」同码防枚举）。
+//   · translations 全量替换（deleteMany+createMany）；重复 locale 入事务前
+//     400（同 albums 翻译处理：撞唯一索引是 500 不是 400）。
+//   · 审计 resourceId=albumId（与 album.* 动作族统一，便于「某相册全部操作」
+//     检索），metadata.categoryId 指向具体分类；update 额外记 fields。
+//   · 删除：分类+翻译行同事务删除。契约注「分类下仍有照片时是否允许删除由
+//     服务端策略决定」——P1a 照片写入路径（Task 18+）尚未给 photos.categoryId
+//     赋值，此处不做照片计数检查，Task 20 照片分类赋值时再补。
+import { HttpStatus, Injectable } from '@nestjs/common';
+import { ErrorCodes } from '@photo/contracts';
+import { ApiException } from '../api-exception';
+import type { components } from '@photo/contracts';
+import type { Prisma } from '@photo/db-cn';
+import type { AuthUser } from '../auth/session.guard';
+import { PrismaService } from '../prisma/prisma.service';
+import type {
+  CategoryCreateRequestDto,
+  CategoryUpdateRequestDto,
+} from './dto';
+import { PermissionsService } from './permissions.service';
+import {
+  albumForbidden,
+  albumNotFound,
+  validationFailed,
+} from './support';
+
+export type CategoryResponse = components['schemas']['Category'];
+export type CategoryTranslationResponse =
+  components['schemas']['CategoryTranslation'];
+
+type CategoryRow = Prisma.categoriesGetPayload<Prisma.categoriesDefaultArgs>;
+type CategoryTranslationRow = Prisma.category_translationsGetPayload<
+  Prisma.category_translationsDefaultArgs
+>;
+
+/** 契约 CategoryUpdateRequest 属性序（审计 metadata.fields 序列，同 albums）。 */
+const CATEGORY_UPDATE_FIELD_ORDER = [
+  'sortOrder',
+  'translations',
+] as const satisfies readonly (keyof CategoryUpdateRequestDto)[];
+
+/** translations 重复 locale → 400（入事务前，理由同 albums.service）。 */
+function assertNoDuplicateLocale(
+  translations: Array<{ locale: string }>,
+): void {
+  const locales = translations.map((t) => t.locale);
+  if (new Set(locales).size !== locales.length) {
+    throw validationFailed('translations 存在重复 locale');
+  }
+}
+
+function toCategoryResponse(
+  category: CategoryRow,
+  translations: CategoryTranslationRow[],
+): CategoryResponse {
+  return {
+    id: category.id,
+    albumId: category.albumId,
+    sortOrder: category.sortOrder,
+    translations: translations.map((row) => ({
+      // locale 取值来自入参枚举校验，收窄为契约 Locale（同 albums 翻译）。
+      locale: row.locale as CategoryTranslationResponse['locale'],
+      name: row.name,
+    })),
+  };
+}
+
+@Injectable()
+export class CategoriesService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly permissions: PermissionsService,
+  ) {}
+
+  /** 创建分类（契约 createCategory）：201 返回 Category。 */
+  async create(
+    user: AuthUser,
+    albumId: string,
+    dto: CategoryCreateRequestDto,
+  ): Promise<CategoryResponse> {
+    assertNoDuplicateLocale(dto.translations);
+    await this.assertAlbumManaged(user, albumId);
+
+    const categoryId = await this.prisma.$transaction(async (tx) => {
+      const category = await tx.categories.create({
+        data: { albumId, sortOrder: dto.sortOrder ?? 0 },
+        select: { id: true },
+      });
+      await tx.category_translations.createMany({
+        data: dto.translations.map((t) => ({
+          categoryId: category.id,
+          locale: t.locale,
+          name: t.name,
+        })),
+      });
+      await tx.audit_logs.create({
+        data: {
+          actorId: user.id,
+          action: 'album.category.add',
+          resourceId: albumId,
+          metadata: { categoryId: category.id },
+        },
+      });
+      return category.id;
+    });
+    const category = await this.loadCategory(categoryId);
+    if (category === null) {
+      // 刚提交就读不到只可能是并发异常路径，按 5xx 兜底（同 albums.create）。
+      throw new ApiException(
+        ErrorCodes.INTERNAL_ERROR,
+        'Internal server error',
+        HttpStatus.INTERNAL_SERVER_ERROR,
+      );
+    }
+    return category;
+  }
+
+  /** 更新分类（契约 updateCategory）：部分更新，translations 全量替换。 */
+  async update(
+    user: AuthUser,
+    categoryId: string,
+    dto: CategoryUpdateRequestDto,
+  ): Promise<CategoryResponse> {
+    // 契约 minProperties:1（判据同 albums.service.update：plainToInstance 后
+    // 声明属性以 undefined 成键，以「任一字段已赋值」为准）。
+    const fields = CATEGORY_UPDATE_FIELD_ORDER.filter(
+      (key) => dto[key] !== undefined,
+    );
+    if (fields.length === 0) {
+      throw validationFailed('请求体至少需要包含一个待更新字段');
+    }
+    if (dto.translations !== undefined) {
+      assertNoDuplicateLocale(dto.translations);
+    }
+
+    const existing = await this.assertCategoryManaged(user, categoryId);
+    await this.prisma.$transaction(async (tx) => {
+      await tx.categories.update({
+        where: { id: categoryId },
+        data: { sortOrder: dto.sortOrder },
+      });
+      if (dto.translations !== undefined) {
+        await tx.category_translations.deleteMany({ where: { categoryId } });
+        await tx.category_translations.createMany({
+          data: dto.translations.map((t) => ({
+            categoryId,
+            locale: t.locale,
+            name: t.name,
+          })),
+        });
+      }
+      await tx.audit_logs.create({
+        data: {
+          actorId: user.id,
+          action: 'album.category.update',
+          resourceId: existing.albumId,
+          metadata: { categoryId, fields },
+        },
+      });
+    });
+    const category = await this.loadCategory(categoryId);
+    if (category === null) {
+      throw albumNotFound();
+    }
+    return category;
+  }
+
+  /** 删除分类（契约 deleteCategory）：204 无响应体。 */
+  async remove(user: AuthUser, categoryId: string): Promise<void> {
+    const existing = await this.assertCategoryManaged(user, categoryId);
+    await this.prisma.$transaction(async (tx) => {
+      await tx.category_translations.deleteMany({ where: { categoryId } });
+      await tx.categories.delete({ where: { id: categoryId } });
+      await tx.audit_logs.create({
+        data: {
+          actorId: user.id,
+          action: 'album.category.remove',
+          resourceId: existing.albumId,
+          metadata: { categoryId },
+        },
+      });
+    });
+  }
+
+  /** /albums/{albumId}/categories 的 404/403 顺序映射 + admin 空相册兜底。 */
+  private async assertAlbumManaged(
+    user: AuthUser,
+    albumId: string,
+  ): Promise<void> {
+    if (!(await this.permissions.canViewAlbum(user, albumId))) {
+      throw albumNotFound();
+    }
+    if (!(await this.permissions.canManageAlbum(user, albumId))) {
+      throw albumForbidden('仅创建者或管理员可管理分类');
+    }
+    const album = await this.prisma.albums.findUnique({
+      where: { id: albumId },
+      select: { id: true },
+    });
+    if (album === null) {
+      // admin 视角 canView 恒真，空值兜底同码 404。
+      throw albumNotFound();
+    }
+  }
+
+  /**
+   * /categories/{categoryId} 的 404/403 顺序映射：分类行不存在 → 404（契约
+   * 语义：分类不存在或所属相册不存在/不可见同码）；行存在再按所属相册判
+   * canView → 404 / canManage → 403。返回分类行（含 albumId 供审计）。
+   */
+  private async assertCategoryManaged(
+    user: AuthUser,
+    categoryId: string,
+  ): Promise<CategoryRow> {
+    const category = await this.prisma.categories.findUnique({
+      where: { id: categoryId },
+    });
+    if (category === null) {
+      throw albumNotFound();
+    }
+    if (!(await this.permissions.canViewAlbum(user, category.albumId))) {
+      throw albumNotFound();
+    }
+    if (!(await this.permissions.canManageAlbum(user, category.albumId))) {
+      throw albumForbidden('仅创建者或管理员可管理分类');
+    }
+    return category;
+  }
+
+  /** 组装 Category 形状：主行 + 翻译（locale 升序，确定性输出）。 */
+  private async loadCategory(categoryId: string): Promise<CategoryResponse | null> {
+    const category = await this.prisma.categories.findUnique({
+      where: { id: categoryId },
+    });
+    if (category === null) {
+      return null;
+    }
+    const translations = await this.prisma.category_translations.findMany({
+      where: { categoryId },
+      orderBy: { locale: 'asc' },
+    });
+    return toCategoryResponse(category, translations);
+  }
+}
diff --git a/services/api/src/albums/dto.ts b/services/api/src/albums/dto.ts
index 9c8f2fc..3b37705 100644
--- a/services/api/src/albums/dto.ts
+++ b/services/api/src/albums/dto.ts
@@ -1,5 +1,7 @@
-// services/api/src/albums/dto.ts —— 相册端点入参 DTO（Task 15；Task 16 增补更新版）。
-// 校验约束对齐契约 AlbumCreateRequest / AlbumUpdateRequest / AlbumTranslation：
+// services/api/src/albums/dto.ts —— 相册端点入参 DTO（Task 15；Task 16 增补更新版；
+// Task 17 增补成员/分类）。校验约束对齐契约
+// AlbumCreateRequest / AlbumUpdateRequest / MemberAddRequest /
+// CategoryCreateRequest / CategoryUpdateRequest / AlbumTranslation：
 //   · translations 至少 1 条（minItems: 1），locale 限 P1a 双语枚举；
 //   · defaultLocale 必须有对应翻译条目（跨字段校验，契约 required 语义）；
 //   · endAt 可空（契约 [string,'null']），给值时须晚于 startAt（跨字段校验）；
@@ -13,11 +15,14 @@ import {
   ArrayMinSize,
   IsBoolean,
   IsIn,
+  IsInt,
   IsISO8601,
   IsNotEmpty,
   IsOptional,
   IsString,
   MaxLength,
+  Max,
+  Min,
   Validate,
   ValidateNested,
   ValidatorConstraint,
@@ -222,3 +227,70 @@ export class AlbumUpdateRequestDto {
   @IsBoolean()
   originalDownloadEnabled?: boolean;
 }
+
+// ── 成员（Task 17）──
+
+/**
+ * 契约 MemberAddRequest：userId 必填（已开通账号）；role 缺省 collaborator，
+ * 枚举仅 collaborator——owner 由创建流程产生，经本端点加 owner 属 P4a 管理员
+ * 操作，role='owner' 在 DTO 层即 400。
+ */
+export class MemberAddRequestDto {
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(64) // users.id VarChar(64)
+  userId!: string;
+
+  @IsOptional()
+  @IsIn(['collaborator'])
+  role?: 'collaborator';
+}
+
+// ── 分类（Task 17）──
+
+/** 契约 CategoryTranslation：name minLength 1；列宽 VarChar(128)。 */
+export class CategoryTranslationDto {
+  @IsIn(ALBUM_LOCALES)
+  locale!: AlbumLocale;
+
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(128)
+  name!: string;
+}
+
+/** sortOrder：契约 integer 无界；Int 列物理边界内收为 400（而非溢出 500）。 */
+const SORT_ORDER_MIN = -2_147_483_648;
+const SORT_ORDER_MAX = 2_147_483_647;
+
+export class CategoryCreateRequestDto {
+  @IsOptional()
+  @IsInt()
+  @Min(SORT_ORDER_MIN)
+  @Max(SORT_ORDER_MAX)
+  sortOrder?: number;
+
+  @ArrayMinSize(1)
+  @ValidateNested({ each: true })
+  @Type(() => CategoryTranslationDto)
+  translations!: CategoryTranslationDto[];
+}
+
+/**
+ * 契约 CategoryUpdateRequest：全字段可选 + minProperties:1。空体拒绝在服务层
+ * （同 AlbumUpdateRequestDto：plainToInstance 后声明属性以 undefined 成键，
+ * Object.keys 不可判空，以「任一字段已赋值」为判据）。
+ */
+export class CategoryUpdateRequestDto {
+  @IsOptional()
+  @IsInt()
+  @Min(SORT_ORDER_MIN)
+  @Max(SORT_ORDER_MAX)
+  sortOrder?: number;
+
+  @IsOptional()
+  @ArrayMinSize(1)
+  @ValidateNested({ each: true })
+  @Type(() => CategoryTranslationDto)
+  translations?: CategoryTranslationDto[];
+}
diff --git a/services/api/src/albums/members.controller.ts b/services/api/src/albums/members.controller.ts
new file mode 100644
index 0000000..d0d8884
--- /dev/null
+++ b/services/api/src/albums/members.controller.ts
@@ -0,0 +1,68 @@
+// services/api/src/albums/members.controller.ts —— /albums/{albumId}/members
+// 端点（Task 17）。方法名与契约 operationId 一一对应（addAlbumMember/
+// listAlbumMembers/removeAlbumMember）。控制器级 SessionGuard：三端点全需
+// 认证。控制器只做认证用户透传 + 查询参数规整（复用 albums.controller 的
+// parseLimit/parseCursor，同一契约 bounds/游标语义）；权限与 HTTP 映射由
+// MembersService 抛 ApiException（404 ALBUM_NOT_FOUND / 403 AUTH_FORBIDDEN /
+// 409 MEMBER_CONFLICT）。
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  HttpCode,
+  HttpStatus,
+  Param,
+  Post,
+  Query,
+  Req,
+  UseGuards,
+} from '@nestjs/common';
+import { AuthenticatedRequest, SessionGuard } from '../auth/session.guard';
+import { parseCursor, parseLimit, userOf } from './albums.controller';
+import { MemberAddRequestDto } from './dto';
+import {
+  type MemberListResponse,
+  type MemberResponse,
+  MembersService,
+} from './members.service';
+
+@Controller('albums/:albumId/members')
+@UseGuards(SessionGuard)
+export class MembersController {
+  constructor(private readonly membersService: MembersService) {}
+
+  @Post()
+  addAlbumMember(
+    @Param('albumId') albumId: string,
+    @Body() dto: MemberAddRequestDto,
+    @Req() req: AuthenticatedRequest,
+  ): Promise<MemberResponse> {
+    return this.membersService.add(userOf(req), albumId, dto);
+  }
+
+  @Get()
+  listAlbumMembers(
+    @Param('albumId') albumId: string,
+    @Query('cursor') cursor: string | undefined,
+    @Query('limit') limit: string | undefined,
+    @Req() req: AuthenticatedRequest,
+  ): Promise<MemberListResponse> {
+    return this.membersService.list(
+      userOf(req),
+      albumId,
+      parseCursor(cursor),
+      parseLimit(limit),
+    );
+  }
+
+  @Delete(':userId')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  removeAlbumMember(
+    @Param('albumId') albumId: string,
+    @Param('userId') userId: string,
+    @Req() req: AuthenticatedRequest,
+  ): Promise<void> {
+    return this.membersService.remove(userOf(req), albumId, userId);
+  }
+}
diff --git a/services/api/src/albums/members.service.ts b/services/api/src/albums/members.service.ts
new file mode 100644
index 0000000..ab2ab03
--- /dev/null
+++ b/services/api/src/albums/members.service.ts
@@ -0,0 +1,234 @@
+// services/api/src/albums/members.service.ts —— 相册成员管理（Task 17）。
+// 契约权威：openapi.yaml tags [members]（addAlbumMember/listAlbumMembers/
+// removeAlbumMember）。要点：
+//   · 权限顺序与 albums 一致防枚举：canViewAlbum=false → 404；canManageAlbum
+//     =false → 403（协作者可见不可管）；admin 视角再由空行兜底 404。
+//   · 成员行（album_members）是唯一权限来源（Task 14 结论）：移除=删行，
+//     被移除者下一次请求即刻失去可见性（A02，PermissionsService 无缓存）。
+//   · owner 行不可经本端点产生/删除：邀请 owner 目标 → 400（仅 collaborator
+//     可加，owner 转移属 P4a 管理员操作）；移除 owner → 403。
+//   · 被邀请账号必须已开通（credentialStatus=active 且 sourceStatus≠disabled）：
+//     邀请属管理动作，明示目标账号有效性不构成成员枚举泄露。
+//   · 移除幂等：目标成员行不存在仍 204（契约语义）；仅真实删除落审计
+//     （幂等重删不重复记 album.member.remove）。
+//   · 列表：(addedAt,id) DESC 键集游标（shared/cursor，与相册列表同构）；
+//     users 无 relation（扁平外键），二次查询应用层组装 Member。
+import { HttpStatus, Injectable } from '@nestjs/common';
+import { ErrorCodes } from '@photo/contracts';
+import type { components } from '@photo/contracts';
+import type { Prisma } from '@photo/db-cn';
+import { ApiException } from '../api-exception';
+import type { AuthUser } from '../auth/session.guard';
+import { PrismaService } from '../prisma/prisma.service';
+import {
+  decodeKeysetCursor,
+  encodeKeysetCursor,
+  keysetWhereDesc,
+} from '../shared/cursor';
+import type { MemberAddRequestDto } from './dto';
+import { PermissionsService } from './permissions.service';
+import {
+  albumForbidden,
+  albumNotFound,
+  isUniqueViolationOn,
+  validationFailed,
+} from './support';
+
+export type MemberResponse = components['schemas']['Member'];
+export type MemberListResponse = components['schemas']['MemberList'];
+
+@Injectable()
+export class MembersService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly permissions: PermissionsService,
+  ) {}
+
+  /** 添加协作者（契约 addAlbumMember）：201 返回 Member。 */
+  async add(
+    user: AuthUser,
+    albumId: string,
+    dto: MemberAddRequestDto,
+  ): Promise<MemberResponse> {
+    const { ownerId } = await this.assertManageable(user, albumId);
+
+    // 目标账号须存在且已开通（pending 凭据/已停用均不可加）。
+    const target = await this.prisma.users.findUnique({
+      where: { id: dto.userId },
+      select: {
+        account: true,
+        displayName: true,
+        credentialStatus: true,
+        sourceStatus: true,
+      },
+    });
+    if (
+      target === null ||
+      target.credentialStatus !== 'active' ||
+      target.sourceStatus === 'disabled'
+    ) {
+      throw validationFailed('被邀请的用户不存在或不可用（须为已开通账号）');
+    }
+    // owner 不能经本端点被（重）添加：防重复 owner 行与角色歧义。
+    if (dto.userId === ownerId) {
+      throw validationFailed('owner 由创建流程产生，不能经由本端点添加');
+    }
+
+    const role = dto.role ?? 'collaborator';
+    try {
+      await this.prisma.$transaction(async (tx) => {
+        await tx.album_members.create({
+          data: { albumId, userId: dto.userId, role, status: 'active' },
+        });
+        await tx.audit_logs.create({
+          data: {
+            actorId: user.id,
+            action: 'album.member.add',
+            resourceId: albumId,
+            metadata: { userId: dto.userId, role },
+          },
+        });
+      });
+    } catch (err) {
+      // 并发窗口内重复邀请：唯一索引 @@unique([albumId,userId]) 兜底成契约 409。
+      if (isUniqueViolationOn(err, 'albumId_userId')) {
+        throw new ApiException(
+          ErrorCodes.MEMBER_CONFLICT,
+          '该用户已是相册成员',
+          HttpStatus.CONFLICT,
+        );
+      }
+      throw err;
+    }
+    return {
+      userId: dto.userId,
+      account: target.account,
+      displayName: target.displayName,
+      role,
+      status: 'active',
+    };
+  }
+
+  /** 成员列表（契约 listAlbumMembers）：任何成员/admin 可见；(addedAt,id) DESC。 */
+  async list(
+    user: AuthUser,
+    albumId: string,
+    cursor: string | undefined,
+    limit: number,
+  ): Promise<MemberListResponse> {
+    if (!(await this.permissions.canViewAlbum(user, albumId))) {
+      throw albumNotFound();
+    }
+    // admin 对不存在的 id 权限恒真（非 admin 的可见成员行本身蕴含相册存在），
+    // 空相册兜底同码 404——契约「相册不存在，或当前用户不可见」。
+    const albumExists = await this.prisma.albums.findUnique({
+      where: { id: albumId },
+      select: { id: true },
+    });
+    if (albumExists === null) {
+      throw albumNotFound();
+    }
+    let decoded: ReturnType<typeof decodeKeysetCursor> = null;
+    if (cursor !== undefined && cursor !== '') {
+      decoded = decodeKeysetCursor(cursor);
+      if (decoded === null) {
+        throw validationFailed('cursor 不合法');
+      }
+    }
+
+    const where: Prisma.album_membersWhereInput = { albumId };
+    if (decoded !== null) {
+      Object.assign(where, keysetWhereDesc('addedAt', 'id', decoded));
+    }
+    const rows = await this.prisma.album_members.findMany({
+      where,
+      orderBy: [{ addedAt: 'desc' }, { id: 'desc' }],
+      take: limit + 1, // 多取一条探测 hasMore（同相册列表，免 count 查询）
+    });
+    const hasMore = rows.length > limit;
+    const page = hasMore ? rows.slice(0, limit) : rows;
+
+    const users = await this.prisma.users.findMany({
+      where: { id: { in: page.map((m) => m.userId) } },
+      select: { id: true, account: true, displayName: true },
+    });
+    const byId = new Map(users.map((u) => [u.id, u]));
+
+    const items = page.flatMap((row) => {
+      const u = byId.get(row.userId);
+      // 用户行缺失（P1a 无用户删除，仅可能来自手工改库）：跳过而非报错。
+      return u === undefined
+        ? []
+        : [
+            {
+              userId: row.userId,
+              account: u.account,
+              displayName: u.displayName,
+              role: row.role as MemberResponse['role'],
+              status: row.status as MemberResponse['status'],
+            },
+          ];
+    });
+
+    const last = page.at(-1);
+    const nextCursor =
+      hasMore && last !== undefined
+        ? encodeKeysetCursor({
+            sort: last.addedAt.toISOString(),
+            id: last.id,
+          })
+        : null;
+    return { items, nextCursor, hasMore: nextCursor !== null };
+  }
+
+  /** 移除成员（契约 removeAlbumMember）：幂等 204；owner 不可移除（403）。 */
+  async remove(
+    user: AuthUser,
+    albumId: string,
+    targetUserId: string,
+  ): Promise<void> {
+    const { ownerId } = await this.assertManageable(user, albumId);
+    if (targetUserId === ownerId) {
+      throw albumForbidden('不能移除相册创建者（owner 转移属管理员操作）');
+    }
+    // Task 14：成员行是唯一权限来源，移除=删行（无软删除状态）。
+    await this.prisma.$transaction(async (tx) => {
+      const removed = await tx.album_members.deleteMany({
+        where: { albumId, userId: targetUserId },
+      });
+      if (removed.count > 0) {
+        // 幂等重删（count=0）不重复落审计。
+        await tx.audit_logs.create({
+          data: {
+            actorId: user.id,
+            action: 'album.member.remove',
+            resourceId: albumId,
+            metadata: { userId: targetUserId },
+          },
+        });
+      }
+    });
+  }
+
+  /** 404/403 顺序映射 + admin 空相册兜底（增删均为管理动作，共用入口）。 */
+  private async assertManageable(
+    user: AuthUser,
+    albumId: string,
+  ): Promise<{ ownerId: string }> {
+    if (!(await this.permissions.canViewAlbum(user, albumId))) {
+      throw albumNotFound();
+    }
+    if (!(await this.permissions.canManageAlbum(user, albumId))) {
+      throw albumForbidden('仅创建者或管理员可管理成员');
+    }
+    const album = await this.prisma.albums.findUnique({
+      where: { id: albumId },
+      select: { ownerId: true },
+    });
+    if (album === null) {
+      // admin 对不存在的 id 权限恒真，由空值兜底同码 404。
+      throw albumNotFound();
+    }
+    return album;
+  }
+}
diff --git a/services/api/src/albums/support.ts b/services/api/src/albums/support.ts
new file mode 100644
index 0000000..04ddf36
--- /dev/null
+++ b/services/api/src/albums/support.ts
@@ -0,0 +1,57 @@
+// services/api/src/albums/support.ts —— 相册域服务共用小工具（Task 15 起自
+// albums.service.ts 抽出，Task 17 起 members/categories 服务同用）。
+import { HttpStatus } from '@nestjs/common';
+import { ErrorCodes } from '@photo/contracts';
+import { ApiException } from '../api-exception';
+
+/** 统一 404：不可见（含不存在）同码防 id 枚举（契约 albums/categories 404 语义）。 */
+export function albumNotFound(): ApiException {
+  return new ApiException(
+    ErrorCodes.ALBUM_NOT_FOUND,
+    '相册不存在或不可见',
+    HttpStatus.NOT_FOUND,
+  );
+}
+
+/** 统一 403：可见但无管理权限（协作者视角）。 */
+export function albumForbidden(message = '仅创建者或管理员可操作'): ApiException {
+  return new ApiException(ErrorCodes.AUTH_FORBIDDEN, message, HttpStatus.FORBIDDEN);
+}
+
+/** 统一 400（契约 VALIDATION_FAILED）。 */
+export function validationFailed(message: string): ApiException {
+  return new ApiException(
+    ErrorCodes.VALIDATION_FAILED,
+    message,
+    HttpStatus.BAD_REQUEST,
+  );
+}
+
+/**
+ * P2002 是否命中指定唯一索引。uniqueName 用 Prisma 唯一选择器名（单列
+ * 'publicToken' / 复合 'albumId_userId'）。meta.target 两种形态都兼容：
+ * 字段数组（部分引擎/版本）或 DB 约束名字符串（MySQL 实测形如
+ * 'albums_publicToken_key' / 'album_members_albumId_userId_key'——
+ * 表名前缀 + 选择器名 + _key 后缀，两种后缀都匹配）。
+ */
+export function isUniqueViolationOn(err: unknown, uniqueName: string): boolean {
+  if (typeof err !== 'object' || err === null) {
+    return false;
+  }
+  const { code, meta } = err as { code?: unknown; meta?: { target?: unknown } };
+  if (code !== 'P2002') {
+    return false;
+  }
+  const target = meta?.target;
+  if (Array.isArray(target)) {
+    return target.map(String).includes(uniqueName);
+  }
+  if (typeof target === 'string') {
+    return (
+      target === uniqueName ||
+      target.endsWith(`${uniqueName}_key`) ||
+      target.endsWith(`_${uniqueName}_key`)
+    );
+  }
+  return false;
+}
diff --git a/services/api/test/members-categories.e2e-spec.ts b/services/api/test/members-categories.e2e-spec.ts
new file mode 100644
index 0000000..efaf53e
--- /dev/null
+++ b/services/api/test/members-categories.e2e-spec.ts
@@ -0,0 +1,590 @@
+// services/api/test/members-categories.e2e-spec.ts —— Task 17 成员与分类 e2e（先写后实现）。
+// 认证与 Task 15 相同：Prisma 直种 sessions 行换 Bearer 令牌。覆盖：
+//   成员：owner 邀请已开通同事（userId）→ 201 契约 Member 形状 + DB 行 +
+//         audit album.member.add；重复邀请 409 MEMBER_CONFLICT；邀请 owner/
+//         role=owner/未知账号/未开通/已停用 → 400；成员列表（成员视角 200、
+//         外人 404）与游标分页；移除协作者 204 幂等 + 被移除者即刻失去相册
+//         可见性（A02：GET album → 404）+ audit album.member.remove；owner
+//         自移除 403（转移属 P4a 管理员操作）；协作者增删成员 403。
+//   分类：owner 创建 {sortOrder, translations} → 201 契约 Category；相册详情
+//         按 sortOrder 升序带出分类；PATCH 重排/改名（translations 全量替换）；
+//         DELETE 204 且详情不再列出；不存在/越权 404/403 同相册语义
+//         （ALBUM_NOT_FOUND）；audit album.category.add/update/remove。
+import { randomBytes } from 'node:crypto';
+import { type INestApplication } from '@nestjs/common';
+import { Test } from '@nestjs/testing';
+import request from 'supertest';
+import { PrismaClient } from '@photo/db-cn';
+import { ErrorCodes } from '@photo/contracts';
+import { AppCnModule } from '../src/app-cn.module';
+import { hashSessionToken } from '../src/auth/session.guard';
+import { API_PREFIX } from '../src/shared/constants';
+import { resetDb } from './reset';
+
+/** 契约 Member 的字段全集（形状精确断言用）。 */
+const MEMBER_KEYS = ['userId', 'account', 'displayName', 'role', 'status'].sort();
+/** 契约 Category 的字段全集。 */
+const CATEGORY_KEYS = ['id', 'albumId', 'sortOrder', 'translations'].sort();
+
+describe('members & categories (e2e)', () => {
+  let app: INestApplication;
+  let prisma: PrismaClient;
+
+  let ownerId: string;
+  let inviteeId: string;
+  let collabId: string;
+  let outsiderId: string;
+  let ownerToken: string;
+  let inviteeToken: string;
+  let collabToken: string;
+  let outsiderToken: string;
+  let adminToken: string;
+
+  let albumId: string;
+  /** 依次创建的分类 id（cat1=sortOrder 5、cat2=sortOrder 1）。 */
+  let cat1Id: string;
+  let cat2Id: string;
+
+  beforeAll(async () => {
+    await resetDb();
+    const moduleRef = await Test.createTestingModule({
+      imports: [AppCnModule],
+    }).compile();
+    app = moduleRef.createNestApplication();
+    app.setGlobalPrefix(API_PREFIX);
+    await app.init();
+
+    prisma = new PrismaClient();
+
+    const mkUser = (
+      account: string,
+      extra: { role?: string; sourceStatus?: string; credentialStatus?: string } = {},
+    ) =>
+      prisma.users.create({
+        data: {
+          account,
+          role: extra.role ?? 'staff',
+          passwordHash: 'x',
+          displayName: account,
+          sourceStatus: extra.sourceStatus,
+          credentialStatus: extra.credentialStatus,
+        },
+        select: { id: true },
+      });
+    ownerId = (await mkUser('mc-owner')).id;
+    inviteeId = (await mkUser('mc-invitee')).id;
+    collabId = (await mkUser('mc-collab')).id;
+    outsiderId = (await mkUser('mc-outsider')).id;
+    // 未开通 / 已停用账号：邀请应 400。
+    await mkUser('mc-pending', { credentialStatus: 'pending' });
+    await mkUser('mc-disabled', { sourceStatus: 'disabled' });
+    const adminId = (await mkUser('mc-admin', { role: 'admin' })).id;
+
+    const mkToken = async (userId: string): Promise<string> => {
+      const token = randomBytes(32).toString('hex');
+      await prisma.sessions.create({
+        data: {
+          userId,
+          tokenHash: hashSessionToken(token),
+          expiresAt: new Date(Date.now() + 3_600_000),
+        },
+      });
+      return token;
+    };
+    ownerToken = await mkToken(ownerId);
+    inviteeToken = await mkToken(inviteeId);
+    collabToken = await mkToken(collabId);
+    outsiderToken = await mkToken(outsiderId);
+    adminToken = await mkToken(adminId);
+
+    const res = await request(app.getHttpServer())
+      .post(`/${API_PREFIX}/albums`)
+      .set('Authorization', `Bearer ${ownerToken}`)
+      .send({
+        translations: [
+          { locale: 'zh-CN', title: '成员与分类相册' },
+          { locale: 'en', title: 'Members and Categories' },
+        ],
+        defaultLocale: 'zh-CN',
+        startAt: '2026-12-01T02:00:00.000Z',
+      });
+    expect(res.status).toBe(201);
+    albumId = res.body.id as string;
+  });
+
+  afterAll(async () => {
+    await app.close();
+    await prisma.$disconnect();
+  });
+
+  // ── 成员 ──
+
+  const postMember = (token: string, body: object) =>
+    request(app.getHttpServer())
+      .post(`/${API_PREFIX}/albums/${albumId}/members`)
+      .set('Authorization', `Bearer ${token}`)
+      .send(body);
+
+  const listMembers = (
+    token: string,
+    query?: Record<string, string | number>,
+  ) =>
+    request(app.getHttpServer())
+      .get(`/${API_PREFIX}/albums/${albumId}/members`)
+      .set('Authorization', `Bearer ${token}`)
+      .query(query ?? {});
+
+  const deleteMember = (token: string, userId: string) =>
+    request(app.getHttpServer())
+      .delete(`/${API_PREFIX}/albums/${albumId}/members/${userId}`)
+      .set('Authorization', `Bearer ${token}`);
+
+  it('owner 邀请已开通同事 → 201 Member；DB 成员行；audit album.member.add', async () => {
+    const res = await postMember(ownerToken, { userId: inviteeId });
+    expect(res.status).toBe(201);
+    expect(Object.keys(res.body).sort()).toEqual(MEMBER_KEYS);
+    expect(res.body).toMatchObject({
+      userId: inviteeId,
+      account: 'mc-invitee',
+      displayName: 'mc-invitee',
+      role: 'collaborator',
+      status: 'active',
+    });
+
+    const row = await prisma.album_members.findUnique({
+      where: { albumId_userId: { albumId, userId: inviteeId } },
+    });
+    expect(row).toMatchObject({ role: 'collaborator', status: 'active' });
+
+    const audit = await prisma.audit_logs.findFirst({
+      where: {
+        action: 'album.member.add',
+        actorId: ownerId,
+        resourceId: albumId,
+      },
+    });
+    expect(audit).not.toBeNull();
+    expect((audit?.metadata as { userId?: string })?.userId).toBe(inviteeId);
+  });
+
+  it('重复邀请 → 409 MEMBER_CONFLICT', async () => {
+    const res = await postMember(ownerToken, { userId: inviteeId });
+    expect(res.status).toBe(409);
+    expect(res.body.code).toBe(ErrorCodes.MEMBER_CONFLICT);
+  });
+
+  it('owner 邀请自己 / role=owner / 未知账号 / 未开通 / 已停用 → 400', async () => {
+    const self = await postMember(ownerToken, { userId: ownerId });
+    expect(self.status).toBe(400);
+    expect(self.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+
+    // 本端点仅可添加 collaborator（owner 转移属 P4a 管理员操作）。
+    const asOwner = await postMember(ownerToken, {
+      userId: collabId,
+      role: 'owner',
+    });
+    expect(asOwner.status).toBe(400);
+    expect(asOwner.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+
+    const unknown = await postMember(ownerToken, { userId: 'no-such-user' });
+    expect(unknown.status).toBe(400);
+    expect(unknown.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+    expect(typeof unknown.body.message).toBe('string');
+
+    // 凭据未开通（credentialStatus=pending）与已停用（sourceStatus=disabled）。
+    const pendingUser = await prisma.users.findUnique({
+      where: { account: 'mc-pending' },
+      select: { id: true },
+    });
+    const pending = await postMember(ownerToken, {
+      userId: pendingUser?.id,
+    });
+    expect(pending.status).toBe(400);
+
+    const disabledUser = await prisma.users.findUnique({
+      where: { account: 'mc-disabled' },
+      select: { id: true },
+    });
+    const disabled = await postMember(ownerToken, {
+      userId: disabledUser?.id,
+    });
+    expect(disabled.status).toBe(400);
+    expect(disabled.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+  });
+
+  it('成员列表：成员/管理员视角 200（owner+协作者）；外人员工 404；admin 200', async () => {
+    const ownerList = await listMembers(ownerToken);
+    expect(ownerList.status).toBe(200);
+    expect(ownerList.body.items).toHaveLength(2);
+    const ids = ownerList.body.items.map((m: { userId: string }) => m.userId);
+    expect(ids.sort()).toEqual([inviteeId, ownerId].sort());
+    expect(Object.keys(ownerList.body.items[0]).sort()).toEqual(MEMBER_KEYS);
+    // owner 行的 account/displayName 来自 users 表（扁平外键应用层组装）。
+    const ownerRow = ownerList.body.items.find(
+      (m: { userId: string }) => m.userId === ownerId,
+    );
+    expect(ownerRow).toMatchObject({
+      account: 'mc-owner',
+      displayName: 'mc-owner',
+      role: 'owner',
+      status: 'active',
+    });
+
+    // 被邀请的协作者本人也是成员 → 可见。
+    const memberList = await listMembers(inviteeToken);
+    expect(memberList.status).toBe(200);
+    expect(memberList.body.items).toHaveLength(2);
+
+    const outsiderList = await listMembers(outsiderToken);
+    expect(outsiderList.status).toBe(404);
+    expect(outsiderList.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    const adminList = await listMembers(adminToken);
+    expect(adminList.status).toBe(200);
+    expect(adminList.body.items).toHaveLength(2);
+  });
+
+  it('成员列表游标分页：addedAt DESC 稳定序，hasMore/nextCursor 成对', async () => {
+    // 显式回写互不相同的 addedAt：排序断言与真实写入时序解耦。
+    await prisma.album_members.updateMany({
+      where: { albumId, userId: ownerId },
+      data: { addedAt: new Date('2026-09-10T08:00:00.000Z') },
+    });
+    await prisma.album_members.updateMany({
+      where: { albumId, userId: inviteeId },
+      data: { addedAt: new Date('2026-09-10T10:00:00.000Z') },
+    });
+
+    const page1 = await listMembers(ownerToken, { limit: 1 });
+    expect(page1.status).toBe(200);
+    expect(page1.body.items.map((m: { userId: string }) => m.userId)).toEqual([
+      inviteeId,
+    ]);
+    expect(page1.body.hasMore).toBe(true);
+    expect(typeof page1.body.nextCursor).toBe('string');
+
+    const page2 = await listMembers(ownerToken, {
+      limit: 1,
+      cursor: page1.body.nextCursor,
+    });
+    expect(page2.status).toBe(200);
+    expect(page2.body.items.map((m: { userId: string }) => m.userId)).toEqual([
+      ownerId,
+    ]);
+    expect(page2.body.hasMore).toBe(false);
+    expect(page2.body.nextCursor).toBeNull();
+
+    const badCursor = await listMembers(ownerToken, { cursor: 'garbage' });
+    expect(badCursor.status).toBe(400);
+    expect(badCursor.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+  });
+
+  it('owner 移除协作者 → 204；被移除者即刻失去相册可见性（A02）；重复移除幂等 204；audit album.member.remove', async () => {
+    const res = await deleteMember(ownerToken, inviteeId);
+    expect(res.status).toBe(204);
+
+    // A02 链路：成员行是唯一权限来源，删除行后下一次请求即刻 404。
+    const albumRes = await request(app.getHttpServer())
+      .get(`/${API_PREFIX}/albums/${albumId}`)
+      .set('Authorization', `Bearer ${inviteeToken}`);
+    expect(albumRes.status).toBe(404);
+    expect(albumRes.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    // 成员列表回到仅 owner。
+    const ownerList = await listMembers(ownerToken);
+    expect(ownerList.body.items).toHaveLength(1);
+
+    // 幂等：再次移除同一用户仍 204（目标成员行已不存在）。
+    const again = await deleteMember(ownerToken, inviteeId);
+    expect(again.status).toBe(204);
+
+    // 移除成功的那次落审计（幂等重删不重复落）。
+    const audits = await prisma.audit_logs.findMany({
+      where: {
+        action: 'album.member.remove',
+        actorId: ownerId,
+        resourceId: albumId,
+      },
+    });
+    expect(audits).toHaveLength(1);
+    expect((audits[0]?.metadata as { userId?: string })?.userId).toBe(inviteeId);
+  });
+
+  it('owner 自移除 → 403 AUTH_FORBIDDEN（owner 转移属 P4a 管理员操作）', async () => {
+    const res = await deleteMember(ownerToken, ownerId);
+    expect(res.status).toBe(403);
+    expect(res.body.code).toBe(ErrorCodes.AUTH_FORBIDDEN);
+    // owner 成员行仍在。
+    const row = await prisma.album_members.findUnique({
+      where: { albumId_userId: { albumId, userId: ownerId } },
+    });
+    expect(row).not.toBeNull();
+  });
+
+  it('协作者增删成员 → 403；外人增删 → 404；未认证 → 401', async () => {
+    // 先把 standing collaborator 加进来（owner 操作，复用前述成功路径）。
+    const invite = await postMember(ownerToken, { userId: collabId });
+    expect(invite.status).toBe(201);
+
+    const collabAdd = await postMember(collabToken, { userId: outsiderId });
+    expect(collabAdd.status).toBe(403);
+    expect(collabAdd.body.code).toBe(ErrorCodes.AUTH_FORBIDDEN);
+
+    const collabRemove = await deleteMember(collabToken, ownerId);
+    expect(collabRemove.status).toBe(403);
+    expect(collabRemove.body.code).toBe(ErrorCodes.AUTH_FORBIDDEN);
+
+    const outsiderAdd = await postMember(outsiderToken, { userId: collabId });
+    expect(outsiderAdd.status).toBe(404);
+    expect(outsiderAdd.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    const outsiderRemove = await deleteMember(outsiderToken, collabId);
+    expect(outsiderRemove.status).toBe(404);
+    expect(outsiderRemove.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    const anon = await request(app.getHttpServer())
+      .post(`/${API_PREFIX}/albums/${albumId}/members`)
+      .send({ userId: collabId });
+    expect(anon.status).toBe(401);
+    expect(anon.body.code).toBe(ErrorCodes.AUTH_TOKEN_EXPIRED);
+  });
+
+  it('不存在的相册：邀请/列表/移除 → 404 ALBUM_NOT_FOUND', async () => {
+    const invite = await request(app.getHttpServer())
+      .post(`/${API_PREFIX}/albums/no-such-album/members`)
+      .set('Authorization', `Bearer ${ownerToken}`)
+      .send({ userId: collabId });
+    expect(invite.status).toBe(404);
+    expect(invite.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    const list = await request(app.getHttpServer())
+      .get(`/${API_PREFIX}/albums/no-such-album/members`)
+      .set('Authorization', `Bearer ${ownerToken}`);
+    expect(list.status).toBe(404);
+
+    const remove = await request(app.getHttpServer())
+      .delete(`/${API_PREFIX}/albums/no-such-album/members/${collabId}`)
+      .set('Authorization', `Bearer ${ownerToken}`);
+    expect(remove.status).toBe(404);
+
+    // admin 对不存在的 id 权限恒真：同样兜底 404（而非空列表 200）。
+    const adminList = await request(app.getHttpServer())
+      .get(`/${API_PREFIX}/albums/no-such-album/members`)
+      .set('Authorization', `Bearer ${adminToken}`);
+    expect(adminList.status).toBe(404);
+    expect(adminList.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+  });
+
+  // ── 分类 ──
+
+  const postCategory = (token: string, body: object) =>
+    request(app.getHttpServer())
+      .post(`/${API_PREFIX}/albums/${albumId}/categories`)
+      .set('Authorization', `Bearer ${token}`)
+      .send(body);
+
+  const patchCategory = (token: string, categoryId: string, body: object) =>
+    request(app.getHttpServer())
+      .patch(`/${API_PREFIX}/categories/${categoryId}`)
+      .set('Authorization', `Bearer ${token}`)
+      .send(body);
+
+  const deleteCategory = (token: string, categoryId: string) =>
+    request(app.getHttpServer())
+      .delete(`/${API_PREFIX}/categories/${categoryId}`)
+      .set('Authorization', `Bearer ${token}`);
+
+  const getAlbumCategories = async (): Promise<
+    Array<{ id: string; sortOrder: number; translations: Array<{ locale: string; name: string }> }>
+  > => {
+    const res = await request(app.getHttpServer())
+      .get(`/${API_PREFIX}/albums/${albumId}`)
+      .set('Authorization', `Bearer ${ownerToken}`);
+    expect(res.status).toBe(200);
+    return res.body.categories;
+  };
+
+  it('owner 创建分类 → 201 Category；DB 行；audit album.category.add', async () => {
+    const res = await postCategory(ownerToken, {
+      sortOrder: 5,
+      translations: [
+        { locale: 'zh-CN', name: '外场' },
+        { locale: 'en', name: 'Outdoor' },
+      ],
+    });
+    expect(res.status).toBe(201);
+    expect(Object.keys(res.body).sort()).toEqual(CATEGORY_KEYS);
+    expect(res.body.albumId).toBe(albumId);
+    expect(res.body.sortOrder).toBe(5);
+    // 翻译按 locale 升序（确定性输出）。
+    expect(res.body.translations).toEqual([
+      { locale: 'en', name: 'Outdoor' },
+      { locale: 'zh-CN', name: '外场' },
+    ]);
+    cat1Id = res.body.id as string;
+
+    const rows = await prisma.category_translations.findMany({
+      where: { categoryId: cat1Id },
+    });
+    expect(rows.map((r) => r.locale).sort()).toEqual(['en', 'zh-CN']);
+
+    const audit = await prisma.audit_logs.findFirst({
+      where: {
+        action: 'album.category.add',
+        actorId: ownerId,
+        resourceId: albumId,
+      },
+    });
+    expect(audit).not.toBeNull();
+    expect((audit?.metadata as { categoryId?: string })?.categoryId).toBe(
+      cat1Id,
+    );
+
+    // 第二个分类 sortOrder=1：相册详情按 sortOrder 升序带出。
+    const res2 = await postCategory(ownerToken, {
+      sortOrder: 1,
+      translations: [{ locale: 'zh-CN', name: '签到台' }],
+    });
+    expect(res2.status).toBe(201);
+    cat2Id = res2.body.id as string;
+
+    const categories = await getAlbumCategories();
+    expect(categories.map((c) => c.id)).toEqual([cat2Id, cat1Id]);
+    expect(categories[0]).toMatchObject({ sortOrder: 1 });
+    expect(categories[0].translations).toEqual([
+      { locale: 'zh-CN', name: '签到台' },
+    ]);
+  });
+
+  it('分类校验：重复 locale / 空 translations / 空更新体 → 400', async () => {
+    const dup = await postCategory(ownerToken, {
+      translations: [
+        { locale: 'zh-CN', name: '重复' },
+        { locale: 'zh-CN', name: '重复2' },
+      ],
+    });
+    expect(dup.status).toBe(400);
+    expect(dup.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+
+    const empty = await postCategory(ownerToken, { translations: [] });
+    expect(empty.status).toBe(400);
+    expect(empty.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+
+    const emptyPatch = await patchCategory(ownerToken, cat1Id, {});
+    expect(emptyPatch.status).toBe(400);
+    expect(emptyPatch.body.code).toBe(ErrorCodes.VALIDATION_FAILED);
+  });
+
+  it('owner PATCH 分类：重排 + 改名（translations 全量替换）→ 200；详情次序更新；audit album.category.update', async () => {
+    const res = await patchCategory(ownerToken, cat1Id, {
+      sortOrder: 0,
+      translations: [{ locale: 'zh-CN', name: '主会场' }],
+    });
+    expect(res.status).toBe(200);
+    expect(res.body.sortOrder).toBe(0);
+    // 全量替换：en 名称不复存在。
+    expect(res.body.translations).toEqual([{ locale: 'zh-CN', name: '主会场' }]);
+
+    // DB：旧 en 翻译行已删。
+    const rows = await prisma.category_translations.findMany({
+      where: { categoryId: cat1Id },
+    });
+    expect(rows).toHaveLength(1);
+    expect(rows[0]).toMatchObject({ locale: 'zh-CN', name: '主会场' });
+
+    // 相册详情：cat1(0) 现在排在 cat2(1) 之前。
+    const categories = await getAlbumCategories();
+    expect(categories.map((c) => c.id)).toEqual([cat1Id, cat2Id]);
+
+    const audit = await prisma.audit_logs.findFirst({
+      where: {
+        action: 'album.category.update',
+        actorId: ownerId,
+        resourceId: albumId,
+      },
+    });
+    expect(audit).not.toBeNull();
+    expect(
+      (audit?.metadata as { categoryId?: string })?.categoryId,
+    ).toBe(cat1Id);
+  });
+
+  it('owner DELETE 分类 → 204；详情不再列出；再删 → 404；audit album.category.remove', async () => {
+    const res = await deleteCategory(ownerToken, cat2Id);
+    expect(res.status).toBe(204);
+
+    const categories = await getAlbumCategories();
+    expect(categories.map((c) => c.id)).toEqual([cat1Id]);
+
+    const again = await deleteCategory(ownerToken, cat2Id);
+    expect(again.status).toBe(404);
+    expect(again.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    // DB：分类与翻译行俱删。
+    const categoryRow = await prisma.categories.findUnique({
+      where: { id: cat2Id },
+    });
+    expect(categoryRow).toBeNull();
+    const translationRows = await prisma.category_translations.findMany({
+      where: { categoryId: cat2Id },
+    });
+    expect(translationRows).toHaveLength(0);
+
+    const audit = await prisma.audit_logs.findFirst({
+      where: {
+        action: 'album.category.remove',
+        actorId: ownerId,
+        resourceId: albumId,
+      },
+    });
+    expect(audit).not.toBeNull();
+  });
+
+  it('不存在的分类 id：PATCH/DELETE → 404 ALBUM_NOT_FOUND（契约分类 404 语义）', async () => {
+    const patch = await patchCategory(ownerToken, 'no-such-category', {
+      sortOrder: 2,
+    });
+    expect(patch.status).toBe(404);
+    expect(patch.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    const del = await deleteCategory(ownerToken, 'no-such-category');
+    expect(del.status).toBe(404);
+    expect(del.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+  });
+
+  it('协作者分类增删改 → 403；外人员工 → 404；admin 创建 → 201', async () => {
+    const collabCreate = await postCategory(collabToken, {
+      translations: [{ locale: 'zh-CN', name: '协作者的分类' }],
+    });
+    expect(collabCreate.status).toBe(403);
+    expect(collabCreate.body.code).toBe(ErrorCodes.AUTH_FORBIDDEN);
+
+    const collabPatch = await patchCategory(collabToken, cat1Id, {
+      sortOrder: 9,
+    });
+    expect(collabPatch.status).toBe(403);
+    expect(collabPatch.body.code).toBe(ErrorCodes.AUTH_FORBIDDEN);
+
+    const collabDelete = await deleteCategory(collabToken, cat1Id);
+    expect(collabDelete.status).toBe(403);
+    expect(collabDelete.body.code).toBe(ErrorCodes.AUTH_FORBIDDEN);
+
+    const outsiderCreate = await postCategory(outsiderToken, {
+      translations: [{ locale: 'zh-CN', name: '外人的分类' }],
+    });
+    expect(outsiderCreate.status).toBe(404);
+    expect(outsiderCreate.body.code).toBe(ErrorCodes.ALBUM_NOT_FOUND);
+
+    const adminCreate = await postCategory(adminToken, {
+      sortOrder: 2,
+      translations: [{ locale: 'en', name: 'Admin Corner' }],
+    });
+    expect(adminCreate.status).toBe(201);
+
+    const anon = await request(app.getHttpServer())
+      .post(`/${API_PREFIX}/albums/${albumId}/categories`)
+      .send({ translations: [{ locale: 'zh-CN', name: '匿名分类' }] });
+    expect(anon.status).toBe(401);
+    expect(anon.body.code).toBe(ErrorCodes.AUTH_TOKEN_EXPIRED);
+  });
+});