diff --git a/src/modules/files/files.controller.ts b/src/modules/files/files.controller.ts
index b6d4ef1..0ee4ec2 100644
--- a/src/modules/files/files.controller.ts
+++ b/src/modules/files/files.controller.ts
@@ -1,61 +1,64 @@
-import {
-  Controller,
-  Get,
-  Post,
-  Delete,
-  Body,
-  Param,
-} from '@nestjs/common';
+import { Controller, Get, Post, Delete, Body, Param, BadRequestException } from '@nestjs/common';
 import { ApiTags, ApiOperation, ApiBearerAuth, ApiResponse } from '@nestjs/swagger';
 import { FilesService } from './files.service';
 import { CreateUploadUrlDto, CompleteUploadDto } from './dto';
 import { CurrentUser } from '../../common/decorators/current-user.decorator';
 import { FileUploadRateLimit } from '../../common/decorators/rate-limit.decorator';
+import { QuotaGuardService } from '../membership/quota-guard.service';
 import type { UserPayload } from '../../common/types';
 
 @ApiTags('files')
 @Controller('files')
 @ApiBearerAuth()
 export class FilesController {
-  constructor(private readonly filesService: FilesService) {}
+  constructor(
+    private readonly filesService: FilesService,
+    private readonly quotaGuard: QuotaGuardService,
+  ) {}
 
   @Post('upload-url')
   @FileUploadRateLimit()
   @ApiOperation({ summary: '获取预签名上传 URL' })
-  @ApiResponse({ status: 201, description: '返回预签名 URL，客户端直接 PUT 文件到 COS' })
-  async createUploadUrl(
-    @CurrentUser() user: UserPayload,
-    @Body() dto: CreateUploadUrlDto,
-  ) {
-    return this.filesService.requestUploadUrl(user.id, dto);
+  async createUploadUrl(@CurrentUser() user: UserPayload, @Body() dto: CreateUploadUrlDto) {
+    const userId = user.id;
+    const opId = `upload:${userId}:${dto.filename}:${Date.now()}`;
+    // M-MEMBER-01-CLOSE-04B: file_size first check
+    const sizeCheck = await this.quotaGuard.check(userId, 'file_size_bytes', `${opId}:size`);
+    const declSize = (dto as any).sizeBytes ?? 0;
+    if (sizeCheck.limit > 0 && declSize > sizeCheck.limit) {
+      throw new BadRequestException({ errorCode: 'FILE_SIZE_LIMIT_EXCEEDED', message: 'File too large', quotaType: 'file_size_bytes', limit: sizeCheck.limit, used: 0, remaining: 0, resetAt: null, upgradeAvailable: true });
+    }
+    // Reserve storage bytes
+    const storageCheck = await this.quotaGuard.check(userId, 'storage_bytes', `${opId}:storage`, declSize);
+    if (!storageCheck.allowed) throw new BadRequestException(this.quotaGuard.buildError(storageCheck));
+
+    try {
+      const result = await this.filesService.requestUploadUrl(userId, dto);
+      return { ...result, _quotaOp: opId };
+    } catch { this.quotaGuard.cancel(`${opId}:storage`).catch(() => {}); throw new BadRequestException('Upload init failed'); }
   }
 
   @Post('complete')
   @FileUploadRateLimit()
   @ApiOperation({ summary: '确认上传完成' })
-  @ApiResponse({ status: 201, description: '验证 COS 中文件存在并创建数据库记录' })
-  async completeUpload(
-    @CurrentUser() user: UserPayload,
-    @Body() dto: CompleteUploadDto,
-  ) {
-    return this.filesService.confirmUpload(user.id, dto);
+  async completeUpload(@CurrentUser() user: UserPayload, @Body() dto: CompleteUploadDto) {
+    const result = await this.filesService.confirmUpload(user.id, dto);
+    return result;
   }
 
   @Get(':id')
   @ApiOperation({ summary: '获取文件信息及下载 URL' })
-  async getFile(
-    @CurrentUser() user: UserPayload,
-    @Param('id') id: string,
-  ) {
+  async getFile(@CurrentUser() user: UserPayload, @Param('id') id: string) {
     return this.filesService.getFile(user.id, id);
   }
 
   @Delete(':id')
   @ApiOperation({ summary: '删除文件（COS + 数据库）' })
-  async deleteFile(
-    @CurrentUser() user: UserPayload,
-    @Param('id') id: string,
-  ) {
-    return this.filesService.deleteFile(user.id, id);
+  async deleteFile(@CurrentUser() user: UserPayload, @Param('id') id: string) {
+    const file = await this.filesService.getFile(user.id, id);
+    const result = await this.filesService.deleteFile(user.id, id);
+    // M-MEMBER-01-CLOSE-04B: release storage on delete
+    if (file?.sizeBytes) this.quotaGuard.cancel(`upload:${user.id}:delete:${id}`).catch(() => {});
+    return result;
   }
 }
diff --git a/src/modules/files/files.module.ts b/src/modules/files/files.module.ts
index 1dc84a5..1610163 100644
--- a/src/modules/files/files.module.ts
+++ b/src/modules/files/files.module.ts
@@ -4,9 +4,10 @@ import { AdminFilesController } from './admin-files.controller';
 import { FilesService } from './files.service';
 import { FilesRepository } from './files.repository';
 import { ContentSafetyModule } from '../content-safety/content-safety.module';
+import { MembershipModule } from '../membership/membership.module';
 
 @Module({
-  imports: [ContentSafetyModule],
+  imports: [ContentSafetyModule, MembershipModule],
   controllers: [FilesController, AdminFilesController],
   providers: [FilesService, FilesRepository],
   exports: [FilesService],