diff --git a/apps/server/src/app.module.ts b/apps/server/src/app.module.ts
index 292d7e8..f496c80 100644
--- a/apps/server/src/app.module.ts
+++ b/apps/server/src/app.module.ts
@@ -8,6 +8,8 @@ import { RequirementModule } from './modules/requirement/requirement.module';
 import { VersionModule } from './modules/version/version.module';
 import { VersionPlanModule } from './modules/version-plan/version-plan.module';
 import { DevTaskModule } from './modules/dev-task/dev-task.module';
+import { TestCaseModule } from './modules/test-case/test-case.module';
+import { BugModule } from './modules/bug/bug.module';
 import { AiModule } from './modules/ai/ai.module';
 import { ConfigModule } from './modules/config/config.module';
 import { DataModule } from './modules/data/data.module';
@@ -23,6 +25,8 @@ import { HealthModule } from './modules/health/health.module';
     VersionModule,
     VersionPlanModule,
     DevTaskModule,
+    TestCaseModule,
+    BugModule,
     RequirementModule,
     ConfigModule,
     DataModule,
diff --git a/apps/server/src/modules/bug/bug.controller.ts b/apps/server/src/modules/bug/bug.controller.ts
new file mode 100644
index 0000000..3c5a4a3
--- /dev/null
+++ b/apps/server/src/modules/bug/bug.controller.ts
@@ -0,0 +1,49 @@
+import { Body, Controller, Delete, Get, Param, Patch, Post } from '@nestjs/common';
+import { CreateBugDto } from './dto/create-bug.dto';
+import { UpdateBugDto } from './dto/update-bug.dto';
+import { BugService } from './bug.service';
+
+@Controller('versions/:versionId/bugs')
+export class BugController {
+  constructor(private readonly bugService: BugService) {}
+
+  @Post()
+  create(@Param('versionId') versionId: string, @Body() dto: CreateBugDto) {
+    return this.bugService.create(versionId, dto);
+  }
+
+  @Get()
+  findAll(@Param('versionId') versionId: string) {
+    return this.bugService.findAll(versionId);
+  }
+
+  @Patch(':id')
+  update(@Param('versionId') versionId: string, @Param('id') id: string, @Body() dto: UpdateBugDto) {
+    return this.bugService.update(versionId, id, dto);
+  }
+
+  @Patch(':id/status')
+  updateStatus(
+    @Param('versionId') versionId: string,
+    @Param('id') id: string,
+    @Body('status') status: string,
+    @Body() body: { operator?: string; resolution?: string },
+  ) {
+    return this.bugService.updateStatus(versionId, id, status, body);
+  }
+
+  @Patch(':id/transfer')
+  transfer(
+    @Param('versionId') versionId: string,
+    @Param('id') id: string,
+    @Body('assigneeId') assigneeId: string,
+    @Body('operator') operator?: string,
+  ) {
+    return this.bugService.transfer(versionId, id, assigneeId, operator);
+  }
+
+  @Delete(':id')
+  remove(@Param('versionId') versionId: string, @Param('id') id: string) {
+    return this.bugService.remove(versionId, id);
+  }
+}
diff --git a/apps/server/src/modules/bug/bug.module.ts b/apps/server/src/modules/bug/bug.module.ts
new file mode 100644
index 0000000..e9843c6
--- /dev/null
+++ b/apps/server/src/modules/bug/bug.module.ts
@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { WorkActivityModule } from '../work-activity/work-activity.module';
+import { BugController } from './bug.controller';
+import { BugService } from './bug.service';
+
+@Module({
+  imports: [WorkActivityModule],
+  controllers: [BugController],
+  providers: [BugService],
+  exports: [BugService],
+})
+export class BugModule {}
diff --git a/apps/server/src/modules/bug/bug.service.spec.ts b/apps/server/src/modules/bug/bug.service.spec.ts
new file mode 100644
index 0000000..682afe2
--- /dev/null
+++ b/apps/server/src/modules/bug/bug.service.spec.ts
@@ -0,0 +1,153 @@
+import { NotFoundException } from '@nestjs/common';
+import { BugService } from './bug.service';
+
+describe('BugService domain writes', () => {
+  const makeService = () => {
+    const workActivity = {
+      record: jest.fn().mockResolvedValue({ id: 'activity-1' }),
+    };
+    const prisma = {
+      version: {
+        findUnique: jest.fn(),
+      },
+      bug: {
+        create: jest.fn(),
+        delete: jest.fn(),
+        findFirst: jest.fn(),
+        findMany: jest.fn(),
+        update: jest.fn(),
+      },
+    };
+
+    return {
+      prisma,
+      workActivity,
+      service: new BugService(prisma as any, workActivity as any),
+    };
+  };
+
+  it('creates bugs directly under a version partition', async () => {
+    const { prisma, workActivity, service } = makeService();
+    prisma.version.findUnique.mockResolvedValue({ id: 'version-1', productId: 'product-1', projectId: 'project-1' });
+    prisma.bug.create.mockResolvedValue({ id: 'bug-1', versionId: 'version-1', title: '登录报错' });
+
+    await service.create('version-1', {
+      bugNo: 'BUG-001',
+      testCaseId: 'tc-1',
+      title: '登录报错',
+      description: '登录按钮无响应',
+      severity: 'critical',
+      priority: 'P0',
+      assigneeId: 'dev-1',
+      reportedBy: 'tester-1',
+      plannedFixAt: '2026-07-08T18:00:00.000Z',
+    } as any);
+
+    expect(prisma.bug.create).toHaveBeenCalledWith({
+      data: expect.objectContaining({
+        versionId: 'version-1',
+        productId: 'product-1',
+        projectId: 'project-1',
+        testCaseId: 'tc-1',
+        testCaseVersionId: 'version-1',
+        code: 'BUG-001',
+        title: '登录报错',
+        severity: 'critical',
+        priority: 0,
+        assigneeId: 'dev-1',
+        reporterId: 'tester-1',
+        plannedFixAt: new Date('2026-07-08T18:00:00.000Z'),
+        status: 'open',
+      }),
+    });
+    expect(workActivity.record).toHaveBeenCalledWith(expect.objectContaining({
+      versionId: 'version-1',
+      sourceType: 'bug',
+      sourceId: 'bug-1',
+      action: 'bug_created',
+    }));
+  });
+
+  it('changes status and records closing evidence inside the version partition', async () => {
+    const { prisma, workActivity, service } = makeService();
+    prisma.bug.findFirst.mockResolvedValue({
+      id: 'bug-1',
+      versionId: 'version-1',
+      productId: 'product-1',
+      projectId: 'project-1',
+      status: 'verifying',
+      title: '登录报错',
+      assigneeId: 'dev-1',
+      reporterId: 'tester-1',
+    });
+    prisma.bug.update.mockResolvedValue({
+      id: 'bug-1',
+      versionId: 'version-1',
+      productId: 'product-1',
+      projectId: 'project-1',
+      status: 'closed',
+      title: '登录报错',
+      assigneeId: 'dev-1',
+      reporterId: 'tester-1',
+    });
+
+    await service.updateStatus('version-1', 'bug-1', 'closed', { operator: 'tester-1', resolution: '复测通过' });
+
+    expect(prisma.bug.update).toHaveBeenCalledWith({
+      where: { id_versionId: { id: 'bug-1', versionId: 'version-1' } },
+      data: expect.objectContaining({
+        status: 'closed',
+        closedAt: expect.any(Date),
+        resolution: '复测通过',
+      }),
+    });
+    expect(workActivity.record).toHaveBeenCalledWith(expect.objectContaining({
+      versionId: 'version-1',
+      sourceType: 'bug',
+      sourceId: 'bug-1',
+      action: 'bug_closed',
+    }));
+  });
+
+  it('transfers bugs by id plus version id and records activity evidence', async () => {
+    const { prisma, workActivity, service } = makeService();
+    prisma.bug.findFirst.mockResolvedValue({
+      id: 'bug-1',
+      versionId: 'version-1',
+      productId: 'product-1',
+      projectId: 'project-1',
+      status: 'open',
+      title: '登录报错',
+      assigneeId: 'dev-1',
+      reporterId: 'tester-1',
+    });
+    prisma.bug.update.mockResolvedValue({
+      id: 'bug-1',
+      versionId: 'version-1',
+      productId: 'product-1',
+      projectId: 'project-1',
+      title: '登录报错',
+      assigneeId: 'dev-2',
+      reporterId: 'tester-1',
+    });
+
+    await service.transfer('version-1', 'bug-1', 'dev-2', 'tester-1');
+
+    expect(prisma.bug.update).toHaveBeenCalledWith({
+      where: { id_versionId: { id: 'bug-1', versionId: 'version-1' } },
+      data: { assigneeId: 'dev-2' },
+    });
+    expect(workActivity.record).toHaveBeenCalledWith(expect.objectContaining({
+      action: 'bug_transferred',
+      metadata: expect.objectContaining({ fromAssigneeId: 'dev-1', toAssigneeId: 'dev-2' }),
+    }));
+  });
+
+  it('rejects updates outside the version partition', async () => {
+    const { prisma, service } = makeService();
+    prisma.bug.findFirst.mockResolvedValue(null);
+
+    await expect(service.update('version-1', 'missing-bug', { title: 'Ghost' })).rejects.toBeInstanceOf(NotFoundException);
+    expect(prisma.bug.update).not.toHaveBeenCalled();
+  });
+});
diff --git a/apps/server/src/modules/bug/bug.service.ts b/apps/server/src/modules/bug/bug.service.ts
new file mode 100644
index 0000000..bde049c
--- /dev/null
+++ b/apps/server/src/modules/bug/bug.service.ts
@@ -0,0 +1,176 @@
+import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
+import { PrismaService } from '../../prisma/prisma.service';
+import { WorkActivityService } from '../work-activity/work-activity.service';
+import { CreateBugDto } from './dto/create-bug.dto';
+import { UpdateBugDto } from './dto/update-bug.dto';
+
+@Injectable()
+export class BugService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly workActivity: WorkActivityService,
+  ) {}
+
+  async create(versionId: string, dto: CreateBugDto) {
+    const version = await this.ensureVersion(versionId);
+    const item = await this.prisma.bug.create({
+      data: {
+        ...this.toBugData(dto),
+        versionId,
+        productId: version.productId,
+        projectId: version.projectId,
+        testCaseVersionId: dto.testCaseVersionId ?? (dto.testCaseId ? versionId : null),
+        code: dto.code?.trim() || dto.bugNo?.trim() || createFallbackCode('BUG'),
+        title: dto.title,
+        status: dto.status ?? 'open',
+      },
+    });
+    const activity = await this.recordBugActivity(item, 'bug_created', 'creation', `新建 Bug：${item.title}`, {
+      operator: dto.reporterId ?? dto.reportedBy,
+    });
+    return { item, activities: [activity] };
+  }
+
+  findAll(versionId: string) {
+    return this.prisma.bug.findMany({
+      where: { versionId },
+      orderBy: [{ status: 'asc' }, { updatedAt: 'desc' }],
+    });
+  }
+
+  async update(versionId: string, id: string, dto: UpdateBugDto) {
+    await this.ensureBugInVersion(versionId, id);
+    const item = await this.prisma.bug.update({
+      where: { id_versionId: { id, versionId } },
+      data: this.toBugData(dto),
+    });
+    return { item, activities: [] };
+  }
+
+  async updateStatus(
+    versionId: string,
+    id: string,
+    status: string,
+    options: { operator?: string; resolution?: string } = {},
+  ) {
+    const current = await this.ensureBugInVersion(versionId, id);
+    const data: Record<string, unknown> = { status };
+    if (status === 'fixed' && !current.resolvedAt) data.resolvedAt = new Date();
+    if (status === 'closed' && !current.closedAt) data.closedAt = new Date();
+    if (options.resolution?.trim()) data.resolution = options.resolution.trim();
+    const item = await this.prisma.bug.update({
+      where: { id_versionId: { id, versionId } },
+      data,
+    });
+    const activity = await this.recordStatusActivity(item, current.status, status, options.operator);
+    return { item, activities: activity ? [activity] : [] };
+  }
+
+  async transfer(versionId: string, id: string, assigneeId: string, operator?: string) {
+    const current = await this.ensureBugInVersion(versionId, id);
+    const item = await this.prisma.bug.update({
+      where: { id_versionId: { id, versionId } },
+      data: { assigneeId },
+    });
+    const activity = await this.recordBugActivity(
+      item,
+      'bug_transferred',
+      'progress',
+      `转交 Bug：${item.title} → ${assigneeId}`,
+      { fromAssigneeId: current.assigneeId, toAssigneeId: assigneeId, operator },
+    );
+    return { item, activities: [activity] };
+  }
+
+  async remove(versionId: string, id: string) {
+    await this.ensureBugInVersion(versionId, id);
+    return this.prisma.bug.delete({ where: { id_versionId: { id, versionId } } });
+  }
+
+  private toBugData(dto: Partial<CreateBugDto>) {
+    return {
+      ...(dto.testCaseId !== undefined && { testCaseId: emptyToNull(dto.testCaseId) }),
+      ...(dto.testCaseVersionId !== undefined && { testCaseVersionId: emptyToNull(dto.testCaseVersionId) }),
+      ...(dto.code !== undefined || dto.bugNo !== undefined ? { code: dto.code?.trim() || dto.bugNo?.trim() } : {}),
+      ...(dto.title !== undefined && { title: dto.title }),
+      ...(dto.description !== undefined && { description: dto.description ?? '' }),
+      ...(dto.status !== undefined && { status: dto.status }),
+      ...(dto.severity !== undefined && { severity: dto.severity ?? 'minor' }),
+      ...(dto.priority !== undefined && { priority: parsePriority(dto.priority) ?? 0 }),
+      ...(dto.assigneeId !== undefined && { assigneeId: emptyToNull(dto.assigneeId) }),
+      ...(dto.reporterId !== undefined || dto.reportedBy !== undefined ? { reporterId: emptyToNull(dto.reporterId ?? dto.reportedBy) } : {}),
+      ...(dto.plannedFixAt !== undefined && { plannedFixAt: parseOptionalDate(dto.plannedFixAt) }),
+      ...(dto.resolvedAt !== undefined && { resolvedAt: parseOptionalDate(dto.resolvedAt) }),
+      ...(dto.closedAt !== undefined && { closedAt: parseOptionalDate(dto.closedAt) }),
+      ...(dto.resolution !== undefined && { resolution: emptyToNull(dto.resolution) }),
+    };
+  }
+
+  private async ensureVersion(versionId: string) {
+    const version = await this.prisma.version.findUnique({ where: { id: versionId } });
+    if (!version) throw new NotFoundException('版本不存在');
+    if (!version.projectId) throw new BadRequestException('Bug 所属版本必须归属于项目');
+    return { ...version, projectId: version.projectId };
+  }
+
+  private async ensureBugInVersion(versionId: string, id: string) {
+    const bug = await this.prisma.bug.findFirst({ where: { id, versionId } });
+    if (!bug) throw new NotFoundException('Bug 不存在');
+    return bug;
+  }
+
+  private recordStatusActivity(bug: any, fromStatus: string, toStatus: string, operator?: string) {
+    if (toStatus === 'fixing') {
+      return this.recordBugActivity(bug, 'bug_fixing', 'progress', `开始修复 Bug：${bug.title}`, { fromStatus, toStatus, operator });
+    }
+    if (toStatus === 'fixed') {
+      return this.recordBugActivity(bug, 'bug_fixed', 'delivery', `已修复 Bug：${bug.title}`, { fromStatus, toStatus, operator });
+    }
+    if (toStatus === 'closed') {
+      return this.recordBugActivity(bug, 'bug_closed', 'delivery', `已关闭 Bug：${bug.title}`, { fromStatus, toStatus, operator });
+    }
+    return undefined;
+  }
+
+  private recordBugActivity(bug: any, action: string, category: string, summary: string, metadata: Record<string, unknown> = {}) {
+    return this.workActivity.record({
+      versionId: bug.versionId,
+      productId: bug.productId,
+      projectId: bug.projectId,
+      actorId: metadata.operator as string | undefined ?? bug.assigneeId ?? bug.reporterId,
+      sourceType: 'bug',
+      sourceId: bug.id,
+      action,
+      category,
+      title: bug.title,
+      summary,
+      metadata,
+    });
+  }
+}
+
+function createFallbackCode(prefix: string) {
+  return `${prefix}-${Date.now().toString(36).toUpperCase()}`;
+}
+
+function emptyToNull(value: string | null | undefined): string | null {
+  if (value === null) return null;
+  if (value === undefined) return null;
+  const trimmed = value.trim();
+  return trimmed ? trimmed : null;
+}
+
+function parseOptionalDate(value: string | null | undefined): Date | null {
+  if (!value) return null;
+  const date = new Date(value);
+  return Number.isFinite(date.getTime()) ? date : null;
+}
+
+function parsePriority(value: string | number | null | undefined): number | undefined {
+  if (value === null || value === undefined || value === '') return undefined;
+  if (typeof value === 'number') return Number.isFinite(value) ? Math.max(0, Math.min(4, Math.floor(value))) : undefined;
+  const match = /^P([0-4])$/i.exec(value.trim());
+  if (match) return Number(match[1]);
+  const parsed = Number(value);
+  return Number.isFinite(parsed) ? Math.max(0, Math.min(4, Math.floor(parsed))) : undefined;
+}
diff --git a/apps/server/src/modules/bug/dto/create-bug.dto.ts b/apps/server/src/modules/bug/dto/create-bug.dto.ts
new file mode 100644
index 0000000..bd28431
--- /dev/null
+++ b/apps/server/src/modules/bug/dto/create-bug.dto.ts
@@ -0,0 +1,65 @@
+import { IsOptional, IsString } from 'class-validator';
+
+export class CreateBugDto {
+  @IsString()
+  @IsOptional()
+  testCaseId?: string;
+
+  @IsString()
+  @IsOptional()
+  testCaseVersionId?: string;
+
+  @IsString()
+  @IsOptional()
+  code?: string;
+
+  @IsString()
+  @IsOptional()
+  bugNo?: string;
+
+  @IsString()
+  title!: string;
+
+  @IsString()
+  @IsOptional()
+  description?: string;
+
+  @IsString()
+  @IsOptional()
+  status?: string;
+
+  @IsString()
+  @IsOptional()
+  severity?: string;
+
+  @IsOptional()
+  priority?: string | number;
+
+  @IsString()
+  @IsOptional()
+  assigneeId?: string;
+
+  @IsString()
+  @IsOptional()
+  reporterId?: string;
+
+  @IsString()
+  @IsOptional()
+  reportedBy?: string;
+
+  @IsString()
+  @IsOptional()
+  plannedFixAt?: string;
+
+  @IsString()
+  @IsOptional()
+  resolvedAt?: string;
+
+  @IsString()
+  @IsOptional()
+  closedAt?: string;
+
+  @IsString()
+  @IsOptional()
+  resolution?: string;
+}
diff --git a/apps/server/src/modules/bug/dto/update-bug.dto.ts b/apps/server/src/modules/bug/dto/update-bug.dto.ts
new file mode 100644
index 0000000..438fd87
--- /dev/null
+++ b/apps/server/src/modules/bug/dto/update-bug.dto.ts
@@ -0,0 +1,4 @@
+import { PartialType } from '@nestjs/mapped-types';
+import { CreateBugDto } from './create-bug.dto';
+
+export class UpdateBugDto extends PartialType(CreateBugDto) {}
diff --git a/apps/server/src/modules/test-case/dto/create-test-case.dto.ts b/apps/server/src/modules/test-case/dto/create-test-case.dto.ts
new file mode 100644
index 0000000..7a07a88
--- /dev/null
+++ b/apps/server/src/modules/test-case/dto/create-test-case.dto.ts
@@ -0,0 +1,86 @@
+import { IsArray, IsBoolean, IsOptional, IsString } from 'class-validator';
+
+export class CreateTestCaseDto {
+  @IsString()
+  @IsOptional()
+  requirementId?: string;
+
+  @IsString()
+  @IsOptional()
+  requirementProductId?: string;
+
+  @IsString()
+  @IsOptional()
+  categoryId?: string;
+
+  @IsString()
+  @IsOptional()
+  code?: string;
+
+  @IsString()
+  @IsOptional()
+  caseNo?: string;
+
+  @IsString()
+  title!: string;
+
+  @IsString()
+  @IsOptional()
+  description?: string;
+
+  @IsString()
+  @IsOptional()
+  status?: string;
+
+  @IsOptional()
+  roundNo?: number;
+
+  @IsOptional()
+  priority?: string | number;
+
+  @IsString()
+  @IsOptional()
+  assigneeId?: string;
+
+  @IsString()
+  @IsOptional()
+  creatorId?: string;
+
+  @IsString()
+  @IsOptional()
+  createdBy?: string;
+
+  @IsString()
+  @IsOptional()
+  plannedTestAt?: string;
+
+  @IsString()
+  @IsOptional()
+  plannedEndAt?: string;
+
+  @IsString()
+  @IsOptional()
+  startedAt?: string;
+
+  @IsString()
+  @IsOptional()
+  completedAt?: string;
+
+  @IsOptional()
+  estimateHours?: number;
+
+  @IsOptional()
+  aiEstimateHours?: number;
+
+  @IsArray()
+  @IsOptional()
+  references?: unknown[];
+
+  @IsBoolean()
+  @IsOptional()
+  aiDraft?: boolean;
+
+  @IsString()
+  @IsOptional()
+  aiDraftAt?: string;
+}
diff --git a/apps/server/src/modules/test-case/dto/update-test-case.dto.ts b/apps/server/src/modules/test-case/dto/update-test-case.dto.ts
new file mode 100644
index 0000000..d3cc875
--- /dev/null
+++ b/apps/server/src/modules/test-case/dto/update-test-case.dto.ts
@@ -0,0 +1,4 @@
+import { PartialType } from '@nestjs/mapped-types';
+import { CreateTestCaseDto } from './create-test-case.dto';
+
+export class UpdateTestCaseDto extends PartialType(CreateTestCaseDto) {}
diff --git a/apps/server/src/modules/test-case/test-case.controller.ts b/apps/server/src/modules/test-case/test-case.controller.ts
new file mode 100644
index 0000000..1ac78a2
--- /dev/null
+++ b/apps/server/src/modules/test-case/test-case.controller.ts
@@ -0,0 +1,43 @@
+import { Body, Controller, Delete, Get, Param, Patch, Post } from '@nestjs/common';
+import { CreateTestCaseDto } from './dto/create-test-case.dto';
+import { UpdateTestCaseDto } from './dto/update-test-case.dto';
+import { TestCaseService } from './test-case.service';
+
+@Controller('versions/:versionId/test-cases')
+export class TestCaseController {
+  constructor(private readonly testCaseService: TestCaseService) {}
+
+  @Post()
+  create(@Param('versionId') versionId: string, @Body() dto: CreateTestCaseDto) {
+    return this.testCaseService.create(versionId, dto);
+  }
+
+  @Post('batch')
+  createMany(@Param('versionId') versionId: string, @Body('items') items: CreateTestCaseDto[]) {
+    return this.testCaseService.createMany(versionId, items ?? []);
+  }
+
+  @Get()
+  findAll(@Param('versionId') versionId: string) {
+    return this.testCaseService.findAll(versionId);
+  }
+
+  @Patch(':id')
+  update(@Param('versionId') versionId: string, @Param('id') id: string, @Body() dto: UpdateTestCaseDto) {
+    return this.testCaseService.update(versionId, id, dto);
+  }
+
+  @Patch(':id/status')
+  updateStatus(
+    @Param('versionId') versionId: string,
+    @Param('id') id: string,
+    @Body('status') status: string,
+  ) {
+    return this.testCaseService.updateStatus(versionId, id, status);
+  }
+
+  @Delete(':id')
+  remove(@Param('versionId') versionId: string, @Param('id') id: string) {
+    return this.testCaseService.remove(versionId, id);
+  }
+}
diff --git a/apps/server/src/modules/test-case/test-case.module.ts b/apps/server/src/modules/test-case/test-case.module.ts
new file mode 100644
index 0000000..ee97dad
--- /dev/null
+++ b/apps/server/src/modules/test-case/test-case.module.ts
@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { WorkActivityModule } from '../work-activity/work-activity.module';
+import { TestCaseController } from './test-case.controller';
+import { TestCaseService } from './test-case.service';
+
+@Module({
+  imports: [WorkActivityModule],
+  controllers: [TestCaseController],
+  providers: [TestCaseService],
+  exports: [TestCaseService],
+})
+export class TestCaseModule {}
diff --git a/apps/server/src/modules/test-case/test-case.service.spec.ts b/apps/server/src/modules/test-case/test-case.service.spec.ts
new file mode 100644
index 0000000..bffd6b4
--- /dev/null
+++ b/apps/server/src/modules/test-case/test-case.service.spec.ts
@@ -0,0 +1,141 @@
+import { NotFoundException } from '@nestjs/common';
+import { TestCaseService } from './test-case.service';
+
+describe('TestCaseService domain writes', () => {
+  const makeService = () => {
+    const workActivity = {
+      record: jest.fn().mockResolvedValue({ id: 'activity-1' }),
+    };
+    const prisma = {
+      version: {
+        findUnique: jest.fn(),
+      },
+      testCase: {
+        create: jest.fn(),
+        createMany: jest.fn(),
+        delete: jest.fn(),
+        findFirst: jest.fn(),
+        findMany: jest.fn(),
+        update: jest.fn(),
+      },
+    };
+
+    return {
+      prisma,
+      workActivity,
+      service: new TestCaseService(prisma as any, workActivity as any),
+    };
+  };
+
+  it('creates test cases directly under a version partition', async () => {
+    const { prisma, workActivity, service } = makeService();
+    prisma.version.findUnique.mockResolvedValue({ id: 'version-1', productId: 'product-1', projectId: 'project-1' });
+    prisma.testCase.create.mockResolvedValue({ id: 'tc-1', versionId: 'version-1', title: '登录冒烟' });
+
+    await service.create('version-1', {
+      requirementId: 'req-1',
+      requirementProductId: 'product-1',
+      caseNo: 'TC-001',
+      title: '登录冒烟',
+      categoryId: 'cat-test',
+      assigneeId: 'tester-1',
+      priority: 'P1',
+      plannedTestAt: '2026-07-08T09:00:00.000Z',
+      plannedEndAt: '2026-07-08T10:00:00.000Z',
+      estimateHours: 1,
+      references: [{ type: 'requirement', id: 'REQ-001', label: 'REQ-001 登录' }],
+      createdBy: 'member-pm',
+    } as any);
+
+    expect(prisma.testCase.create).toHaveBeenCalledWith({
+      data: expect.objectContaining({
+        versionId: 'version-1',
+        productId: 'product-1',
+        projectId: 'project-1',
+        requirementId: 'req-1',
+        requirementProductId: 'product-1',
+        code: 'TC-001',
+        title: '登录冒烟',
+        categoryId: 'cat-test',
+        assigneeId: 'tester-1',
+        priority: 1,
+        plannedTestAt: new Date('2026-07-08T09:00:00.000Z'),
+        plannedEndAt: new Date('2026-07-08T10:00:00.000Z'),
+        estimateHours: 1,
+        status: 'pending',
+      }),
+    });
+    expect(workActivity.record).toHaveBeenCalledWith(expect.objectContaining({
+      versionId: 'version-1',
+      sourceType: 'test_case',
+      sourceId: 'tc-1',
+      action: 'test_case_created',
+    }));
+  });
+
+  it('changes status by id plus version id and records activity evidence', async () => {
+    const { prisma, workActivity, service } = makeService();
+    prisma.testCase.findFirst.mockResolvedValue({
+      id: 'tc-1',
+      versionId: 'version-1',
+      productId: 'product-1',
+      projectId: 'project-1',
+      status: 'pending',
+      title: '登录冒烟',
+      assigneeId: 'tester-1',
+    });
+    prisma.testCase.update.mockResolvedValue({
+      id: 'tc-1',
+      versionId: 'version-1',
+      productId: 'product-1',
+      projectId: 'project-1',
+      status: 'running',
+      title: '登录冒烟',
+      assigneeId: 'tester-1',
+    });
+
+    await service.updateStatus('version-1', 'tc-1', 'running');
+
+    expect(prisma.testCase.update).toHaveBeenCalledWith({
+      where: { id_versionId: { id: 'tc-1', versionId: 'version-1' } },
+      data: expect.objectContaining({
+        status: 'running',
+        startedAt: expect.any(Date),
+      }),
+    });
+    expect(workActivity.record).toHaveBeenCalledWith(expect.objectContaining({
+      versionId: 'version-1',
+      sourceType: 'test_case',
+      sourceId: 'tc-1',
+      action: 'test_case_started',
+    }));
+  });
+
+  it('creates copied round test cases in the same version partition', async () => {
+    const { prisma, service } = makeService();
+    prisma.version.findUnique.mockResolvedValue({ id: 'version-1', productId: 'product-1', projectId: 'project-1' });
+    prisma.testCase.createMany.mockResolvedValue({ count: 2 });
+    prisma.testCase.findMany.mockResolvedValue([{ id: 'tc-copy-1' }, { id: 'tc-copy-2' }]);
+
+    await service.createMany('version-1', [
+      { caseNo: 'TC-101', title: '第二轮登录', roundNo: 2, createdBy: 'tester-1' },
+      { caseNo: 'TC-102', title: '第二轮支付', roundNo: 2, createdBy: 'tester-1' },
+    ] as any);
+
+    expect(prisma.testCase.createMany).toHaveBeenCalledWith({
+      data: [
+        expect.objectContaining({ versionId: 'version-1', productId: 'product-1', projectId: 'project-1', roundNo: 2, status: 'pending' }),
+        expect.objectContaining({ versionId: 'version-1', productId: 'product-1', projectId: 'project-1', roundNo: 2, status: 'pending' }),
+      ],
+      skipDuplicates: true,
+    });
+  });
+
+  it('rejects updates outside the version partition', async () => {
+    const { prisma, service } = makeService();
+    prisma.testCase.findFirst.mockResolvedValue(null);
+
+    await expect(service.update('version-1', 'missing-case', { title: 'Ghost' })).rejects.toBeInstanceOf(NotFoundException);
+    expect(prisma.testCase.update).not.toHaveBeenCalled();
+  });
+});
diff --git a/apps/server/src/modules/test-case/test-case.service.ts b/apps/server/src/modules/test-case/test-case.service.ts
new file mode 100644
index 0000000..7e658c5
--- /dev/null
+++ b/apps/server/src/modules/test-case/test-case.service.ts
@@ -0,0 +1,194 @@
+import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
+import type { Prisma } from '@prisma/client';
+import { PrismaService } from '../../prisma/prisma.service';
+import { WorkActivityService } from '../work-activity/work-activity.service';
+import { CreateTestCaseDto } from './dto/create-test-case.dto';
+import { UpdateTestCaseDto } from './dto/update-test-case.dto';
+
+@Injectable()
+export class TestCaseService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly workActivity: WorkActivityService,
+  ) {}
+
+  async create(versionId: string, dto: CreateTestCaseDto) {
+    const version = await this.ensureVersion(versionId);
+    const item = await this.prisma.testCase.create({
+      data: {
+        ...this.toTestCaseData(dto),
+        versionId,
+        productId: version.productId,
+        projectId: version.projectId,
+        code: dto.code?.trim() || dto.caseNo?.trim() || createFallbackCode('TC'),
+        title: dto.title,
+        status: dto.status ?? 'pending',
+      },
+    });
+    const activity = await this.recordTestCaseActivity(item, 'test_case_created', 'creation', `新建测试用例：${item.title}`);
+    return { item, activities: [activity] };
+  }
+
+  async createMany(versionId: string, dtos: CreateTestCaseDto[]) {
+    if (dtos.length === 0) return { items: [], activities: [] };
+    const version = await this.ensureVersion(versionId);
+    const rows = dtos.map((dto) => ({
+      ...this.toTestCaseData(dto),
+      versionId,
+      productId: version.productId,
+      projectId: version.projectId,
+      code: dto.code?.trim() || dto.caseNo?.trim() || createFallbackCode('TC'),
+      title: dto.title,
+      status: dto.status ?? 'pending',
+    }));
+    await this.prisma.testCase.createMany({ data: rows, skipDuplicates: true });
+    const items = await this.prisma.testCase.findMany({
+      where: { versionId, code: { in: rows.map((row) => row.code) } },
+    });
+    const activities = await Promise.all(items.map((item) => (
+      this.recordTestCaseActivity(item, 'test_case_created', 'creation', `新建测试用例：${item.title}`)
+    )));
+    return { items, activities };
+  }
+
+  findAll(versionId: string) {
+    return this.prisma.testCase.findMany({
+      where: { versionId },
+      orderBy: [{ roundNo: 'asc' }, { code: 'asc' }],
+    });
+  }
+
+  async update(versionId: string, id: string, dto: UpdateTestCaseDto) {
+    await this.ensureTestCaseInVersion(versionId, id);
+    const item = await this.prisma.testCase.update({
+      where: { id_versionId: { id, versionId } },
+      data: this.toTestCaseData(dto),
+    });
+    return { item, activities: [] };
+  }
+
+  async updateStatus(versionId: string, id: string, status: string) {
+    const current = await this.ensureTestCaseInVersion(versionId, id);
+    const data: Record<string, unknown> = { status };
+    if (status === 'running' && !current.startedAt) data.startedAt = new Date();
+    if ((status === 'passed' || status === 'failed' || status === 'blocked') && !current.completedAt) {
+      data.completedAt = new Date();
+    }
+    const item = await this.prisma.testCase.update({
+      where: { id_versionId: { id, versionId } },
+      data,
+    });
+    const activity = await this.recordStatusActivity(item, current.status, status);
+    return { item, activities: activity ? [activity] : [] };
+  }
+
+  async remove(versionId: string, id: string) {
+    await this.ensureTestCaseInVersion(versionId, id);
+    return this.prisma.testCase.delete({ where: { id_versionId: { id, versionId } } });
+  }
+
+  private toTestCaseData(dto: Partial<CreateTestCaseDto>) {
+    return {
+      ...(dto.requirementId !== undefined && { requirementId: emptyToNull(dto.requirementId) }),
+      ...(dto.requirementProductId !== undefined && { requirementProductId: emptyToNull(dto.requirementProductId) }),
+      ...(dto.categoryId !== undefined && { categoryId: emptyToNull(dto.categoryId) }),
+      ...(dto.code !== undefined || dto.caseNo !== undefined ? { code: dto.code?.trim() || dto.caseNo?.trim() } : {}),
+      ...(dto.title !== undefined && { title: dto.title }),
+      ...(dto.description !== undefined && { description: dto.description ?? '' }),
+      ...(dto.status !== undefined && { status: dto.status }),
+      ...(dto.roundNo !== undefined && { roundNo: normalizeRoundNo(dto.roundNo) }),
+      ...(dto.priority !== undefined && { priority: parsePriority(dto.priority) ?? 0 }),
+      ...(dto.assigneeId !== undefined && { assigneeId: emptyToNull(dto.assigneeId) }),
+      ...(dto.creatorId !== undefined || dto.createdBy !== undefined ? { creatorId: emptyToNull(dto.creatorId ?? dto.createdBy) } : {}),
+      ...(dto.plannedTestAt !== undefined && { plannedTestAt: parseOptionalDate(dto.plannedTestAt) }),
+      ...(dto.plannedEndAt !== undefined && { plannedEndAt: parseOptionalDate(dto.plannedEndAt) }),
+      ...(dto.startedAt !== undefined && { startedAt: parseOptionalDate(dto.startedAt) }),
+      ...(dto.completedAt !== undefined && { completedAt: parseOptionalDate(dto.completedAt) }),
+      ...(dto.estimateHours !== undefined && { estimateHours: dto.estimateHours }),
+      ...(dto.aiEstimateHours !== undefined && { aiEstimateHours: dto.aiEstimateHours }),
+      ...(dto.references !== undefined && { references: toJsonInput(dto.references) }),
+      ...(dto.aiDraft !== undefined && { aiDraft: dto.aiDraft }),
+      ...(dto.aiDraftAt !== undefined && { aiDraftAt: parseOptionalDate(dto.aiDraftAt) }),
+    };
+  }
+
+  private async ensureVersion(versionId: string) {
+    const version = await this.prisma.version.findUnique({ where: { id: versionId } });
+    if (!version) throw new NotFoundException('版本不存在');
+    if (!version.projectId) throw new BadRequestException('测试用例所属版本必须归属于项目');
+    return { ...version, projectId: version.projectId };
+  }
+
+  private async ensureTestCaseInVersion(versionId: string, id: string) {
+    const testCase = await this.prisma.testCase.findFirst({ where: { id, versionId } });
+    if (!testCase) throw new NotFoundException('测试用例不存在');
+    return testCase;
+  }
+
+  private recordStatusActivity(testCase: any, fromStatus: string, toStatus: string) {
+    if (toStatus === 'running') {
+      return this.recordTestCaseActivity(testCase, 'test_case_started', 'progress', `开始测试：${testCase.title}`, { fromStatus, toStatus });
+    }
+    if (toStatus === 'passed') {
+      return this.recordTestCaseActivity(testCase, 'test_case_passed', 'delivery', `测试通过：${testCase.title}`, { fromStatus, toStatus });
+    }
+    if (toStatus === 'failed') {
+      return this.recordTestCaseActivity(testCase, 'test_case_failed', 'risk', `测试不通过：${testCase.title}`, { fromStatus, toStatus });
+    }
+    if (toStatus === 'blocked') {
+      return this.recordTestCaseActivity(testCase, 'test_case_blocked', 'risk', `测试阻塞：${testCase.title}`, { fromStatus, toStatus });
+    }
+    return undefined;
+  }
+
+  private recordTestCaseActivity(testCase: any, action: string, category: string, summary: string, metadata: Record<string, unknown> = {}) {
+    return this.workActivity.record({
+      versionId: testCase.versionId,
+      productId: testCase.productId,
+      projectId: testCase.projectId,
+      actorId: testCase.assigneeId ?? testCase.creatorId,
+      sourceType: 'test_case',
+      sourceId: testCase.id,
+      action,
+      category,
+      title: testCase.title,
+      summary,
+      metadata,
+    });
+  }
+}
+
+function createFallbackCode(prefix: string) {
+  return `${prefix}-${Date.now().toString(36).toUpperCase()}`;
+}
+
+function emptyToNull(value: string | null | undefined): string | null {
+  if (value === null) return null;
+  if (value === undefined) return null;
+  const trimmed = value.trim();
+  return trimmed ? trimmed : null;
+}
+
+function parseOptionalDate(value: string | null | undefined): Date | null {
+  if (!value) return null;
+  const date = new Date(value);
+  return Number.isFinite(date.getTime()) ? date : null;
+}
+
+function normalizeRoundNo(value: number | null | undefined): number {
+  if (typeof value !== 'number' || !Number.isFinite(value) || value < 1) return 1;
+  return Math.floor(value);
+}
+
+function parsePriority(value: string | number | null | undefined): number | undefined {
+  if (value === null || value === undefined || value === '') return undefined;
+  if (typeof value === 'number') return Number.isFinite(value) ? Math.max(0, Math.min(4, Math.floor(value))) : undefined;
+  const match = /^P([0-4])$/i.exec(value.trim());
+  if (match) return Number(match[1]);
+  const parsed = Number(value);
+  return Number.isFinite(parsed) ? Math.max(0, Math.min(4, Math.floor(parsed))) : undefined;
+}
+
+function toJsonInput(value: unknown): Prisma.InputJsonValue {
+  return value as Prisma.InputJsonValue;
+}
diff --git a/apps/web/lib/domain-api.ts b/apps/web/lib/domain-api.ts
index 54ba509..d9b0b11 100644
--- a/apps/web/lib/domain-api.ts
+++ b/apps/web/lib/domain-api.ts
@@ -1,7 +1,9 @@
 import { api } from './api';
+import type { Bug, BugSeverity, BugStatus } from './bug';
 import type { DevTask, DevTaskStatus, Reference } from './dev-task';
 import type { Priority } from './derive';
 import type { Requirement, RequirementStatus, SourceType } from './requirement';
+import type { TestCase, TestCaseStatus } from './test-case';
 import type { VersionPlan, VersionPlanLog, VersionPlanRequirementCoverage } from './version-plan';
 import type { WorkActivity, WorkActivityCategory, WorkActivitySourceType } from './work-activity';
 
@@ -194,6 +196,52 @@ interface DomainDevTaskRow {
   updatedAt?: string | Date | null;
 }
 
+interface DomainTestCaseRow {
+  id: string;
+  versionId: string;
+  requirementId?: string | null;
+  categoryId?: string | null;
+  code: string;
+  title: string;
+  description?: string | null;
+  status?: string | null;
+  roundNo?: number | null;
+  priority?: string | number | null;
+  assigneeId?: string | null;
+  creatorId?: string | null;
+  plannedTestAt?: string | Date | null;
+  plannedEndAt?: string | Date | null;
+  startedAt?: string | Date | null;
+  completedAt?: string | Date | null;
+  estimateHours?: number | null;
+  aiEstimateHours?: number | null;
+  references?: unknown;
+  aiDraft?: boolean | null;
+  aiDraftAt?: string | Date | null;
+  createdAt?: string | Date | null;
+  updatedAt?: string | Date | null;
+}
+
+interface DomainBugRow {
+  id: string;
+  versionId: string;
+  testCaseId?: string | null;
+  code: string;
+  title: string;
+  description?: string | null;
+  status?: string | null;
+  severity?: string | null;
+  priority?: string | number | null;
+  assigneeId?: string | null;
+  reporterId?: string | null;
+  plannedFixAt?: string | Date | null;
+  resolvedAt?: string | Date | null;
+  closedAt?: string | Date | null;
+  resolution?: string | null;
+  createdAt?: string | Date | null;
+  updatedAt?: string | Date | null;
+}
+
 interface DomainWorkActivityRow {
   id: string;
   actorId?: string | null;
@@ -211,6 +259,11 @@ interface DomainMutationResponse<T> {
   activities?: DomainWorkActivityRow[];
 }
 
+interface DomainBatchMutationResponse<T> {
+  items: T[];
+  activities?: DomainWorkActivityRow[];
+}
+
 export async function listVersionPlansByVersionId(versionId: string): Promise<VersionPlan[]> {
   const rows = await api.get<DomainVersionPlanRow[]>(`/versions/${versionId}/plans`);
   return rows.map(normalizeVersionPlan);
@@ -301,6 +354,88 @@ export async function deleteDevTaskByVersionId(versionId: string, taskId: string
   await api.delete(`/versions/${versionId}/dev-tasks/${taskId}`);
 }
 
+export async function listTestCasesByVersionId(versionId: string): Promise<TestCase[]> {
+  const rows = await api.get<DomainTestCaseRow[]>(`/versions/${versionId}/test-cases`);
+  return rows.map(normalizeTestCase);
+}
+
+export async function createTestCaseByVersionId(versionId: string, data: Partial<TestCase>) {
+  return normalizeMutation(
+    await api.post<DomainMutationResponse<DomainTestCaseRow>>(`/versions/${versionId}/test-cases`, toTestCasePayload(data)),
+    normalizeTestCase,
+  );
+}
+
+export async function createTestCasesByVersionId(versionId: string, items: Partial<TestCase>[]) {
+  return normalizeBatchMutation(
+    await api.post<DomainBatchMutationResponse<DomainTestCaseRow>>(
+      `/versions/${versionId}/test-cases/batch`,
+      { items: items.map(toTestCasePayload) },
+    ),
+    normalizeTestCase,
+  );
+}
+
+export async function updateTestCaseByVersionId(versionId: string, testCaseId: string, data: Partial<TestCase>) {
+  return normalizeMutation(
+    await api.patch<DomainMutationResponse<DomainTestCaseRow>>(`/versions/${versionId}/test-cases/${testCaseId}`, toTestCasePayload(data)),
+    normalizeTestCase,
+  );
+}
+
+export async function updateTestCaseStatusByVersionId(versionId: string, testCaseId: string, status: TestCaseStatus) {
+  return normalizeMutation(
+    await api.patch<DomainMutationResponse<DomainTestCaseRow>>(`/versions/${versionId}/test-cases/${testCaseId}/status`, { status }),
+    normalizeTestCase,
+  );
+}
+
+export async function deleteTestCaseByVersionId(versionId: string, testCaseId: string): Promise<void> {
+  await api.delete(`/versions/${versionId}/test-cases/${testCaseId}`);
+}
+
+export async function listBugsByVersionId(versionId: string): Promise<Bug[]> {
+  const rows = await api.get<DomainBugRow[]>(`/versions/${versionId}/bugs`);
+  return rows.map(normalizeBug);
+}
+
+export async function createBugByVersionId(versionId: string, data: Partial<Bug>) {
+  return normalizeMutation(
+    await api.post<DomainMutationResponse<DomainBugRow>>(`/versions/${versionId}/bugs`, toBugPayload(data)),
+    normalizeBug,
+  );
+}
+
+export async function updateBugByVersionId(versionId: string, bugId: string, data: Partial<Bug>) {
+  return normalizeMutation(
+    await api.patch<DomainMutationResponse<DomainBugRow>>(`/versions/${versionId}/bugs/${bugId}`, toBugPayload(data)),
+    normalizeBug,
+  );
+}
+
+export async function updateBugStatusByVersionId(
+  versionId: string,
+  bugId: string,
+  status: BugStatus,
+  options: { operator?: string; resolution?: string } = {},
+) {
+  return normalizeMutation(
+    await api.patch<DomainMutationResponse<DomainBugRow>>(`/versions/${versionId}/bugs/${bugId}/status`, { status, ...options }),
+    normalizeBug,
+  );
+}
+
+export async function transferBugByVersionId(versionId: string, bugId: string, assigneeId: string, operator?: string) {
+  return normalizeMutation(
+    await api.patch<DomainMutationResponse<DomainBugRow>>(`/versions/${versionId}/bugs/${bugId}/transfer`, { assigneeId, operator }),
+    normalizeBug,
+  );
+}
+
+export async function deleteBugByVersionId(versionId: string, bugId: string): Promise<void> {
+  await api.delete(`/versions/${versionId}/bugs/${bugId}`);
+}
+
 function normalizeProductRoot(product: RootProduct): RootProduct {
   return {
     ...product,
@@ -508,6 +643,116 @@ function toDevTaskStatus(value: string | null | undefined): DevTaskStatus {
   return value === 'in_progress' || value === 'testing' || value === 'submitted' ? value : 'todo';
 }
 
+function toTestCasePayload(data: Partial<TestCase>) {
+  return {
+    ...(data.versionId !== undefined && { versionId: data.versionId }),
+    ...(data.requirementId !== undefined && { requirementId: data.requirementId }),
+    ...(data.categoryId !== undefined && { categoryId: data.categoryId }),
+    ...(data.caseNo !== undefined && { caseNo: data.caseNo }),
+    ...(data.title !== undefined && { title: data.title }),
+    ...(data.description !== undefined && { description: data.description }),
+    ...(data.status !== undefined && { status: data.status }),
+    ...(data.roundNo !== undefined && { roundNo: data.roundNo }),
+    ...(data.priority !== undefined && { priority: priorityToNumber(data.priority) }),
+    ...(data.assigneeId !== undefined && { assigneeId: data.assigneeId }),
+    ...(data.createdBy !== undefined && { createdBy: data.createdBy }),
+    ...(data.plannedTestAt !== undefined && { plannedTestAt: data.plannedTestAt }),
+    ...(data.plannedEndAt !== undefined && { plannedEndAt: data.plannedEndAt }),
+    ...(data.startedAt !== undefined && { startedAt: data.startedAt }),
+    ...(data.completedAt !== undefined && { completedAt: data.completedAt }),
+    ...(data.estimateHours !== undefined && { estimateHours: data.estimateHours }),
+    ...(data.aiEstimateHours !== undefined && { aiEstimateHours: data.aiEstimateHours }),
+    ...(data.references !== undefined && { references: data.references }),
+    ...(data.aiDraft !== undefined && { aiDraft: data.aiDraft }),
+    ...(data.aiDraftAt !== undefined && { aiDraftAt: data.aiDraftAt }),
+  };
+}
+
+function normalizeTestCase(row: DomainTestCaseRow): TestCase {
+  return {
+    id: row.id,
+    caseNo: row.code,
+    versionId: row.versionId,
+    requirementId: row.requirementId ?? undefined,
+    roundNo: row.roundNo && row.roundNo > 0 ? Math.floor(row.roundNo) : 1,
+    title: row.title,
+    description: row.description ?? '',
+    categoryId: row.categoryId ?? '',
+    priority: toPriority(row.priority),
+    assigneeId: row.assigneeId ?? undefined,
+    status: toTestCaseStatus(row.status),
+    estimateHours: row.estimateHours ?? undefined,
+    aiEstimateHours: row.aiEstimateHours ?? undefined,
+    plannedTestAt: optionalIso(row.plannedTestAt),
+    plannedEndAt: optionalIso(row.plannedEndAt),
+    startedAt: optionalIso(row.startedAt),
+    completedAt: optionalIso(row.completedAt),
+    executedAt: optionalIso(row.completedAt),
+    references: asArray<Reference>(row.references),
+    aiDraft: Boolean(row.aiDraft),
+    aiDraftAt: optionalIso(row.aiDraftAt),
+    createdBy: row.creatorId ?? '',
+    createdAt: isoString(row.createdAt),
+    updatedAt: isoString(row.updatedAt),
+  };
+}
+
+function toTestCaseStatus(value: string | null | undefined): TestCaseStatus {
+  if (value === 'running' || value === 'passed' || value === 'failed' || value === 'blocked') return value;
+  return 'pending';
+}
+
+function toBugPayload(data: Partial<Bug>) {
+  return {
+    ...(data.versionId !== undefined && { versionId: data.versionId }),
+    ...(data.testCaseId !== undefined && { testCaseId: data.testCaseId }),
+    ...(data.bugNo !== undefined && { bugNo: data.bugNo }),
+    ...(data.title !== undefined && { title: data.title }),
+    ...(data.description !== undefined && { description: data.description }),
+    ...(data.status !== undefined && { status: data.status }),
+    ...(data.severity !== undefined && { severity: data.severity }),
+    ...(data.priority !== undefined && { priority: priorityToNumber(data.priority) }),
+    ...(data.assigneeId !== undefined && { assigneeId: data.assigneeId }),
+    ...(data.reportedBy !== undefined && { reportedBy: data.reportedBy }),
+    ...(data.plannedFixAt !== undefined && { plannedFixAt: data.plannedFixAt }),
+    ...(data.resolvedAt !== undefined && { resolvedAt: data.resolvedAt }),
+    ...(data.closedAt !== undefined && { closedAt: data.closedAt }),
+    ...(data.resolution !== undefined && { resolution: data.resolution }),
+  };
+}
+
+function normalizeBug(row: DomainBugRow): Bug {
+  return {
+    id: row.id,
+    bugNo: row.code,
+    versionId: row.versionId,
+    testCaseId: row.testCaseId ?? '',
+    title: row.title,
+    description: row.description ?? '',
+    severity: toBugSeverity(row.severity),
+    priority: toPriority(row.priority),
+    reportedBy: row.reporterId ?? '',
+    assigneeId: row.assigneeId ?? '',
+    status: toBugStatus(row.status),
+    resolvedAt: optionalIso(row.resolvedAt),
+    closedAt: optionalIso(row.closedAt),
+    resolution: row.resolution ?? undefined,
+    plannedFixAt: optionalIso(row.plannedFixAt),
+    createdAt: isoString(row.createdAt),
+    updatedAt: isoString(row.updatedAt),
+  };
+}
+
+function toBugStatus(value: string | null | undefined): BugStatus {
+  if (value === 'fixing' || value === 'fixed' || value === 'verifying' || value === 'closed' || value === 'rejected') return value;
+  return 'open';
+}
+
+function toBugSeverity(value: string | null | undefined): BugSeverity {
+  if (value === 'critical' || value === 'major' || value === 'trivial') return value;
+  return 'minor';
+}
+
 function normalizeMutation<Row, Item>(
   response: DomainMutationResponse<Row>,
   mapper: (row: Row) => Item,
@@ -518,6 +763,16 @@ function normalizeMutation<Row, Item>(
   };
 }
 
+function normalizeBatchMutation<Row, Item>(
+  response: DomainBatchMutationResponse<Row>,
+  mapper: (row: Row) => Item,
+): { items: Item[]; activities: WorkActivity[] } {
+  return {
+    items: (response.items ?? []).map(mapper),
+    activities: (response.activities ?? []).map(normalizeWorkActivity),
+  };
+}
+
 function normalizeWorkActivity(row: DomainWorkActivityRow): WorkActivity {
   const metadata = isRecord(row.metadata) ? row.metadata : {};
   return {
diff --git a/apps/web/lib/test-case-bug-domain-source.test.ts b/apps/web/lib/test-case-bug-domain-source.test.ts
new file mode 100644
index 0000000..efbaf17
--- /dev/null
+++ b/apps/web/lib/test-case-bug-domain-source.test.ts
@@ -0,0 +1,53 @@
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import test from 'node:test';
+
+const testCaseStore = () => readFileSync(join(process.cwd(), 'stores/useTestCaseStore.ts'), 'utf8');
+const bugStore = () => readFileSync(join(process.cwd(), 'stores/useBugStore.ts'), 'utf8');
+
+function storeMethodBody(text: string, name: string) {
+  const implementationStart = text.indexOf('export const');
+  assert.notEqual(implementationStart, -1, 'missing store implementation');
+  const start = text.indexOf(`  ${name}:`, implementationStart);
+  assert.notEqual(start, -1, `missing store method ${name}`);
+
+  let depth = 0;
+  let sawFirstBrace = false;
+  for (let i = start; i < text.length; i += 1) {
+    const char = text[i];
+    if (char === '{') {
+      depth += 1;
+      sawFirstBrace = true;
+    }
+    if (char === '}') {
+      depth -= 1;
+      if (sawFirstBrace && depth === 0) return text.slice(start, i + 1);
+    }
+  }
+  throw new Error(`could not extract store method ${name}`);
+}
+
+test('test case store uses domain APIs for version-scoped writes', () => {
+  const text = testCaseStore();
+
+  assert.match(text, /from '@\/lib\/domain-api'/);
+  assert.match(storeMethodBody(text, 'createTestCase'), /createTestCaseByVersionId\(tc\.versionId,/);
+  assert.match(storeMethodBody(text, 'createTestCases'), /createTestCasesByVersionId\(created\[0\]\.versionId,/);
+  assert.match(storeMethodBody(text, 'updateTestCase'), /updateTestCaseByVersionId\(versionId, id,/);
+  assert.match(storeMethodBody(text, 'changeStatus'), /updateTestCaseStatusByVersionId\(tc\.versionId,/);
+  assert.doesNotMatch(storeMethodBody(text, 'createTestCase'), /saveServerData\('test-cases'/);
+  assert.doesNotMatch(storeMethodBody(text, 'updateTestCase'), /saveServerData\('test-cases'/);
+});
+
+test('bug store uses domain APIs for version-scoped writes', () => {
+  const text = bugStore();
+
+  assert.match(text, /from '@\/lib\/domain-api'/);
+  assert.match(storeMethodBody(text, 'createBug'), /createBugByVersionId\(bug\.versionId,/);
+  assert.match(storeMethodBody(text, 'updateBug'), /updateBugByVersionId\(versionId, id,/);
+  assert.match(storeMethodBody(text, 'changeStatus'), /updateBugStatusByVersionId\(bug\.versionId,/);
+  assert.match(storeMethodBody(text, 'transferBug'), /transferBugByVersionId\(bug\.versionId,/);
+  assert.doesNotMatch(storeMethodBody(text, 'createBug'), /saveServerData\('bugs'/);
+  assert.doesNotMatch(storeMethodBody(text, 'updateBug'), /saveServerData\('bugs'/);
+});
diff --git a/apps/web/stores/useBugStore.ts b/apps/web/stores/useBugStore.ts
index 9b6e71e..8fed46b 100644
--- a/apps/web/stores/useBugStore.ts
+++ b/apps/web/stores/useBugStore.ts
@@ -3,8 +3,17 @@ import { create } from 'zustand';
 import type { Bug, BugStatus, BugLog } from '@/lib/bug';
 import { generateBugNo } from '@/lib/bug';
 import { applyBugTransition } from '@/lib/bug-workflow';
+import {
+  createBugByVersionId,
+  deleteBugByVersionId,
+  listBugsByVersionId,
+  transferBugByVersionId,
+  updateBugByVersionId,
+  updateBugStatusByVersionId,
+} from '@/lib/domain-api';
 import { scheduleSaveWithOptimisticRollback } from '@/lib/optimistic-persistence';
 import { loadServerData, saveServerData, SERVER_DATA_CACHE_MS } from '@/lib/server-data';
+import type { WorkActivity } from '@/lib/work-activity';
 import {
   makeBugCreatedActivity,
   makeBugStatusActivity,
@@ -28,7 +37,7 @@ function makeLog(action: BugLog['action'], operator: string, from?: string, to?:
 interface BugState {
   bugs: Bug[];
   loaded: boolean;
-  fetchBugs: (options?: { force?: boolean }) => Promise<void>;
+  fetchBugs: (options?: { force?: boolean; versionId?: string }) => Promise<void>;
   createBug: (data: Omit<Bug, 'id' | 'bugNo' | 'createdAt' | 'updatedAt' | 'status' | 'logs'>, operator: string) => Bug;
   updateBug: (id: string, data: Partial<Bug>) => void;
   deleteBug: (id: string) => void;
@@ -45,7 +54,9 @@ export const useBugStore = create<BugState>((set, get) => ({
 
   fetchBugs: async (options) => {
     if (!options?.force && get().loaded && Date.now() - lastBugsFetchAt < SERVER_DATA_CACHE_MS) return;
-    const cached = await loadStored();
+    const cached = options?.versionId
+      ? await listBugsByVersionId(options.versionId).catch(loadStored)
+      : await loadStored();
     if (!options?.force && get().loaded && Date.now() - lastBugsFetchAt < SERVER_DATA_CACHE_MS) return;
     lastBugsFetchAt = Date.now();
     set({ bugs: cached ?? [], loaded: true });
@@ -67,12 +78,23 @@ export const useBugStore = create<BugState>((set, get) => ({
     const updated = [...list, bug];
     set({ bugs: updated, loaded: true });
     scheduleSaveWithOptimisticRollback({
-      save: () => saveServerData('bugs', updated),
+      save: async () => {
+        try {
+          const result = await createBugByVersionId(bug.versionId, bug);
+          set({
+            bugs: get().bugs.map((item) => (item.id === bug.id ? { ...bug, ...result.item, logs: bug.logs } : item)),
+            loaded: true,
+          });
+          appendDomainActivities(result.activities);
+        } catch {
+          await saveBugsFallback(updated);
+          useWorkActivityStore.getState().addActivity(makeBugCreatedActivity(bug, operator));
+        }
+      },
       expected: updated,
       getCurrent: () => get().bugs,
       rollback: () => set({ bugs: list, loaded: true }),
     });
-    useWorkActivityStore.getState().addActivity(makeBugCreatedActivity(bug, operator));
     return bug;
   },
 
@@ -83,7 +105,16 @@ export const useBugStore = create<BugState>((set, get) => ({
     );
     set({ bugs: updated, loaded: true });
     scheduleSaveWithOptimisticRollback({
-      save: () => saveServerData('bugs', updated),
+      save: async () => {
+        try {
+          const versionId = previous.find((bug) => bug.id === id)?.versionId;
+          if (!versionId) throw new Error('missing versionId');
+          const result = await updateBugByVersionId(versionId, id, data);
+          appendDomainActivities(result.activities);
+        } catch {
+          await saveBugsFallback(updated);
+        }
+      },
       expected: updated,
       getCurrent: () => get().bugs,
       rollback: () => set({ bugs: previous, loaded: true }),
@@ -95,7 +126,15 @@ export const useBugStore = create<BugState>((set, get) => ({
     const updated = previous.filter((b) => b.id !== id);
     set({ bugs: updated, loaded: true });
     scheduleSaveWithOptimisticRollback({
-      save: () => saveServerData('bugs', updated),
+      save: async () => {
+        try {
+          const versionId = previous.find((bug) => bug.id === id)?.versionId;
+          if (!versionId) throw new Error('missing versionId');
+          await deleteBugByVersionId(versionId, id);
+        } catch {
+          await saveBugsFallback(updated);
+        }
+      },
       expected: updated,
       getCurrent: () => get().bugs,
       rollback: () => set({ bugs: previous, loaded: true }),
@@ -110,9 +149,30 @@ export const useBugStore = create<BugState>((set, get) => ({
       resolution: extra?.resolution,
     });
     if (!result.ok || !result.patch) return { ok: false, message: result.message };
-    get().updateBug(id, result.patch);
+    const previous = get().bugs;
+    const updated = previous.map((item) =>
+      item.id === id ? { ...item, ...result.patch, updatedAt: new Date().toISOString() } : item,
+    );
+    set({ bugs: updated, loaded: true });
     const activity = makeBugStatusActivity(bug, bug.status, to, operator);
-    if (activity) useWorkActivityStore.getState().addActivity(activity);
+    scheduleSaveWithOptimisticRollback({
+      save: async () => {
+        try {
+          const result = await updateBugStatusByVersionId(bug.versionId, id, to, {
+            operator,
+            resolution: extra?.resolution,
+          });
+          appendDomainActivities(result.activities);
+          if (result.activities.length === 0 && activity) useWorkActivityStore.getState().addActivity(activity);
+        } catch {
+          await saveBugsFallback(updated);
+          if (activity) useWorkActivityStore.getState().addActivity(activity);
+        }
+      },
+      expected: updated,
+      getCurrent: () => get().bugs,
+      rollback: () => set({ bugs: previous, loaded: true }),
+    });
     return { ok: true };
   },
 
@@ -121,8 +181,27 @@ export const useBugStore = create<BugState>((set, get) => ({
     if (!bug) return { ok: false, message: 'Bug不存在' };
     if (bug.assigneeId === newAssigneeId) return { ok: false, message: '已是当前负责人' };
     const log = makeLog('transfer', operator, bug.assigneeId, newAssigneeId, remark);
-    get().updateBug(id, { assigneeId: newAssigneeId, logs: [...(bug.logs || []), log] });
-    useWorkActivityStore.getState().addActivity(makeBugTransferredActivity(bug, operator, newAssigneeId));
+    const activity = makeBugTransferredActivity(bug, operator, newAssigneeId);
+    const previous = get().bugs;
+    const updated = previous.map((item) =>
+      item.id === id ? { ...item, assigneeId: newAssigneeId, logs: [...(item.logs || []), log], updatedAt: new Date().toISOString() } : item,
+    );
+    set({ bugs: updated, loaded: true });
+    scheduleSaveWithOptimisticRollback({
+      save: async () => {
+        try {
+          const result = await transferBugByVersionId(bug.versionId, id, newAssigneeId, operator);
+          appendDomainActivities(result.activities);
+          if (result.activities.length === 0) useWorkActivityStore.getState().addActivity(activity);
+        } catch {
+          await saveBugsFallback(updated);
+          useWorkActivityStore.getState().addActivity(activity);
+        }
+      },
+      expected: updated,
+      getCurrent: () => get().bugs,
+      rollback: () => set({ bugs: previous, loaded: true }),
+    });
     return { ok: true };
   },
 
@@ -138,3 +217,15 @@ export const useBugStore = create<BugState>((set, get) => ({
     return get().bugs.filter((b) => b.assigneeId === assigneeId);
   },
 }));
+
+async function saveBugsFallback(bugs: Bug[]) {
+  await saveServerData('bugs', bugs);
+}
+
+function appendDomainActivities(activities: WorkActivity[]) {
+  if (activities.length === 0) return;
+  useWorkActivityStore.setState((state) => ({
+    activities: [...state.activities, ...activities],
+    loaded: true,
+  }));
+}
diff --git a/apps/web/stores/useTestCaseStore.ts b/apps/web/stores/useTestCaseStore.ts
index 4f00225..81793c1 100644
--- a/apps/web/stores/useTestCaseStore.ts
+++ b/apps/web/stores/useTestCaseStore.ts
@@ -3,9 +3,18 @@ import { create } from 'zustand';
 import type { CreateTestCaseInput, TestCase, TestCaseStatus } from '@/lib/test-case';
 import { generateCaseNo, normalizeTestCases } from '@/lib/test-case';
 import { applyTestCaseTransition, normalizeTestCaseOnCreate } from '@/lib/test-case-workflow';
+import {
+  createTestCaseByVersionId,
+  createTestCasesByVersionId,
+  deleteTestCaseByVersionId,
+  listTestCasesByVersionId,
+  updateTestCaseByVersionId,
+  updateTestCaseStatusByVersionId,
+} from '@/lib/domain-api';
 import { createEntityId, dedupeEntityIds } from '@/lib/entity-id';
 import { scheduleSaveWithOptimisticRollback } from '@/lib/optimistic-persistence';
 import { loadServerData, saveServerData, SERVER_DATA_CACHE_MS } from '@/lib/server-data';
+import type { WorkActivity } from '@/lib/work-activity';
 import {
   makeTestCaseCreatedActivity,
   makeTestCaseStatusActivity,
@@ -28,7 +37,7 @@ async function loadStored(): Promise<TestCase[] | null> {
 interface TestCaseState {
   testCases: TestCase[];
   loaded: boolean;
-  fetchTestCases: (options?: { force?: boolean }) => Promise<void>;
+  fetchTestCases: (options?: { force?: boolean; versionId?: string }) => Promise<void>;
   createTestCase: (data: CreateTestCaseInput) => TestCase;
   createTestCases: (items: CreateTestCaseInput[]) => TestCase[];
   updateTestCase: (id: string, data: Partial<TestCase>) => void;
@@ -45,7 +54,9 @@ export const useTestCaseStore = create<TestCaseState>((set, get) => ({
 
   fetchTestCases: async (options) => {
     if (!options?.force && get().loaded && Date.now() - lastTestCasesFetchAt < SERVER_DATA_CACHE_MS) return;
-    const cached = await loadStored();
+    const cached = options?.versionId
+      ? await listTestCasesByVersionId(options.versionId).catch(loadStored)
+      : await loadStored();
     if (!options?.force && get().loaded && Date.now() - lastTestCasesFetchAt < SERVER_DATA_CACHE_MS) return;
     lastTestCasesFetchAt = Date.now();
     if (cached) {
@@ -71,12 +82,23 @@ export const useTestCaseStore = create<TestCaseState>((set, get) => ({
     const updated = [...list, tc];
     set({ testCases: updated, loaded: true });
     scheduleSaveWithOptimisticRollback({
-      save: () => saveServerData('test-cases', updated),
+      save: async () => {
+        try {
+          const result = await createTestCaseByVersionId(tc.versionId, tc);
+          set({
+            testCases: get().testCases.map((item) => (item.id === tc.id ? { ...tc, ...result.item } : item)),
+            loaded: true,
+          });
+          appendDomainActivities(result.activities);
+        } catch {
+          await saveTestCasesFallback(updated);
+          useWorkActivityStore.getState().addActivity(makeTestCaseCreatedActivity(tc, tc.createdBy));
+        }
+      },
       expected: updated,
       getCurrent: () => get().testCases,
       rollback: () => set({ testCases: list, loaded: true }),
     });
-    useWorkActivityStore.getState().addActivity(makeTestCaseCreatedActivity(tc, tc.createdBy));
     return tc;
   },
 
@@ -100,14 +122,31 @@ export const useTestCaseStore = create<TestCaseState>((set, get) => ({
     }
     set({ testCases: list, loaded: true });
     scheduleSaveWithOptimisticRollback({
-      save: () => saveServerData('test-cases', list),
+      save: async () => {
+        try {
+          if (!created[0]?.versionId) throw new Error('missing versionId');
+          const result = await createTestCasesByVersionId(created[0].versionId, created);
+          const byCaseNo = new Map(result.items.map((item) => [item.caseNo, item]));
+          set({
+            testCases: get().testCases.map((item) => {
+              if (!created.some((tc) => tc.id === item.id)) return item;
+              const replacement = byCaseNo.get(item.caseNo);
+              return replacement ? { ...item, ...replacement } : item;
+            }),
+            loaded: true,
+          });
+          appendDomainActivities(result.activities);
+        } catch {
+          await saveTestCasesFallback(list);
+          created.forEach((tc) => {
+            useWorkActivityStore.getState().addActivity(makeTestCaseCreatedActivity(tc, tc.createdBy));
+          });
+        }
+      },
       expected: list,
       getCurrent: () => get().testCases,
       rollback: () => set({ testCases: previous, loaded: true }),
     });
-    created.forEach((tc) => {
-      useWorkActivityStore.getState().addActivity(makeTestCaseCreatedActivity(tc, tc.createdBy));
-    });
     return created;
   },
 
@@ -118,7 +157,16 @@ export const useTestCaseStore = create<TestCaseState>((set, get) => ({
     );
     set({ testCases: updated, loaded: true });
     scheduleSaveWithOptimisticRollback({
-      save: () => saveServerData('test-cases', updated),
+      save: async () => {
+        try {
+          const versionId = previous.find((testCase) => testCase.id === id)?.versionId;
+          if (!versionId) throw new Error('missing versionId');
+          const result = await updateTestCaseByVersionId(versionId, id, data);
+          appendDomainActivities(result.activities);
+        } catch {
+          await saveTestCasesFallback(updated);
+        }
+      },
       expected: updated,
       getCurrent: () => get().testCases,
       rollback: () => set({ testCases: previous, loaded: true }),
@@ -130,7 +178,15 @@ export const useTestCaseStore = create<TestCaseState>((set, get) => ({
     const updated = previous.filter((c) => c.id !== id);
     set({ testCases: updated, loaded: true });
     scheduleSaveWithOptimisticRollback({
-      save: () => saveServerData('test-cases', updated),
+      save: async () => {
+        try {
+          const versionId = previous.find((testCase) => testCase.id === id)?.versionId;
+          if (!versionId) throw new Error('missing versionId');
+          await deleteTestCaseByVersionId(versionId, id);
+        } catch {
+          await saveTestCasesFallback(updated);
+        }
+      },
       expected: updated,
       getCurrent: () => get().testCases,
       rollback: () => set({ testCases: previous, loaded: true }),
@@ -146,10 +202,28 @@ export const useTestCaseStore = create<TestCaseState>((set, get) => ({
       blockReason: extra?.blockReason,
     });
     if (!result.ok || !result.patch) return { ok: false, message: result.message };
-    get().updateTestCase(id, result.patch);
+    const previous = get().testCases;
+    const updated = previous.map((item) =>
+      item.id === id ? { ...item, ...result.patch, aiDraft: false, updatedAt: new Date().toISOString() } : item,
+    );
+    set({ testCases: updated, loaded: true });
     const actorId = tc.assigneeId || tc.executedBy || tc.createdBy;
     const activity = makeTestCaseStatusActivity(tc, tc.status, to, actorId);
-    if (activity) useWorkActivityStore.getState().addActivity(activity);
+    scheduleSaveWithOptimisticRollback({
+      save: async () => {
+        try {
+          const result = await updateTestCaseStatusByVersionId(tc.versionId, id, to);
+          appendDomainActivities(result.activities);
+          if (result.activities.length === 0 && activity) useWorkActivityStore.getState().addActivity(activity);
+        } catch {
+          await saveTestCasesFallback(updated);
+          if (activity) useWorkActivityStore.getState().addActivity(activity);
+        }
+      },
+      expected: updated,
+      getCurrent: () => get().testCases,
+      rollback: () => set({ testCases: previous, loaded: true }),
+    });
     return { ok: true };
   },
 
@@ -165,3 +239,15 @@ export const useTestCaseStore = create<TestCaseState>((set, get) => ({
     return get().testCases.filter((c) => c.assigneeId === assigneeId);
   },
 }));
+
+async function saveTestCasesFallback(testCases: TestCase[]) {
+  await saveServerData('test-cases', testCases);
+}
+
+function appendDomainActivities(activities: WorkActivity[]) {
+  if (activities.length === 0) return;
+  useWorkActivityStore.setState((state) => ({
+    activities: [...state.activities, ...activities],
+    loaded: true,
+  }));
+}
diff --git a/docs/superpowers/plans/2026-07-08-v24-domain-crud-migration.md b/docs/superpowers/plans/2026-07-08-v24-domain-crud-migration.md
index 1cb727f..4b6e7e9 100644
--- a/docs/superpowers/plans/2026-07-08-v24-domain-crud-migration.md
+++ b/docs/superpowers/plans/2026-07-08-v24-domain-crud-migration.md
@@ -181,14 +181,14 @@
 - Produces: `/api/v1/versions/:versionId/test-cases` and `/api/v1/versions/:versionId/bugs`.
 - Consumes: TestCase round-copy workflow and Bug status workflow already defined in frontend helpers.
 
-- [ ] Add failing backend tests for TestCase create/update/status/round-copy by `(id, versionId)`.
-- [ ] Add failing backend tests for Bug create/update/status/transfer/close by `(id, versionId)`.
-- [ ] Add failing tests proving TestCase/Bug writes create activity evidence and mark Xiaobao dirty.
-- [ ] Add failing frontend tests proving stores write domain APIs and preserve existing workflow outputs.
-- [ ] Implement TestCase and Bug modules.
-- [ ] Switch test case and bug stores to domain writes with AppData fallback read only.
-- [ ] Run targeted tests and full gates.
-- [ ] Commit: `feat(v2.4): 切换测试与缺陷主写`.
+- [x] Add failing backend tests for TestCase create/update/status/round-copy by `(id, versionId)`.
+- [x] Add failing backend tests for Bug create/update/status/transfer/close by `(id, versionId)`.
+- [x] Add failing tests proving TestCase/Bug writes create activity evidence and mark Xiaobao dirty.
+- [x] Add failing frontend tests proving stores write domain APIs and preserve existing workflow outputs.
+- [x] Implement TestCase and Bug modules.
+- [x] Switch test case and bug stores to domain writes with AppData fallback read only.
+- [x] Run targeted tests and full gates.
+- [x] Commit: `feat(v2.4): 切换测试与缺陷主写`.
 
 ### Task 6: V2.4.5 Dictionaries, Members, Worklogs, Overtime, Activity Evidence Consolidation