diff --git a/server/src/nest/auth/auth.controller.ts b/server/src/nest/auth/auth.controller.ts
index b692eb235..ca31d5561 100644
--- a/server/src/nest/auth/auth.controller.ts
+++ b/server/src/nest/auth/auth.controller.ts
@@ -17,15 +17,13 @@ import {
 import { FileInterceptor } from '@nestjs/platform-express';
 import { isDemoWriteBlocked, DEMO_WRITE_ERROR } from '../common/demo-write';
 import { RuntimeEnvService } from '../app-config/runtime-env.service';
-import { diskStorage } from 'multer';
+import type { Options } from 'multer';
 import type { Request, Response } from 'express';
 import path from 'path';
-import fs from 'fs';
-import { v4 as uuid } from 'uuid';
 import { AuthService } from './auth.service';
 import { TokenService } from '../tokens/token.service';
 import { UserProfileService } from './user-profile.service';
-import { avatarDir } from './auth.helpers';
+import { StorageService } from '../storage/storage.service';
 import {
   ChangePasswordDto,
   MapsKeyUpdateDto,
@@ -49,21 +47,17 @@ import { ManagedForbidden } from '../common/managed';
 
 const WINDOW = 15 * 60 * 1000;
 const ALLOWED_AVATAR_EXTS = ['.jpg', '.jpeg', '.png', '.gif', '.webp'];
-const AVATAR_UPLOAD = {
-  storage: diskStorage({
-    destination: (_req, _file, cb) => { if (!fs.existsSync(avatarDir)) fs.mkdirSync(avatarDir, { recursive: true }); cb(null, avatarDir); },
-    filename: (_req, file, cb) => cb(null, uuid() + path.extname(file.originalname)),
-  }),
-  limits: { fileSize: 5 * 1024 * 1024 },
-  fileFilter: (_req: unknown, file: Express.Multer.File, cb: (err: Error | null, accept: boolean) => void) => {
-    const ext = path.extname(file.originalname).toLowerCase();
-    if (!file.mimetype.startsWith('image/') || !ALLOWED_AVATAR_EXTS.includes(ext)) {
-      const err: Error & { statusCode?: number } = new Error('Only image files (jpg, png, gif, webp) are allowed');
-      err.statusCode = 400;
-      return cb(err, false);
-    }
-    cb(null, true);
-  },
+export const MAX_AVATAR_SIZE = 5 * 1024 * 1024;
+// Consumed by auth.module.ts's MulterModule factory; the storage engine (spool
+// destination + UUID filename) comes from the storage upload factory.
+export const AVATAR_FILE_FILTER: Options['fileFilter'] = (_req, file, cb) => {
+  const ext = path.extname(file.originalname).toLowerCase();
+  if (!file.mimetype.startsWith('image/') || !ALLOWED_AVATAR_EXTS.includes(ext)) {
+    const err: Error & { statusCode?: number } = new Error('Only image files (jpg, png, gif, webp) are allowed');
+    err.statusCode = 400;
+    return cb(err);
+  }
+  cb(null, true);
 };
 
 /**
@@ -77,7 +71,7 @@ const AVATAR_UPLOAD = {
 @Controller('api/auth')
 @UseGuards(JwtAuthGuard)
 export class AuthController {
-  constructor(private readonly auth: AuthService, private readonly profile: UserProfileService, private readonly tokens: TokenService, private readonly rl: RateLimitService, private readonly audit: AuditService, private readonly env: RuntimeEnvService) {}
+  constructor(private readonly auth: AuthService, private readonly profile: UserProfileService, private readonly tokens: TokenService, private readonly rl: RateLimitService, private readonly audit: AuditService, private readonly env: RuntimeEnvService, private readonly storage: StorageService) {}
 
   private limit(bucket: string, req: Request, max: number): void {
     if (!this.rl.check(bucket, req.ip || 'unknown', max, WINDOW, Date.now())) {
@@ -153,7 +147,7 @@ export class AuthController {
 
   @Post('avatar')
   @HttpCode(200)
-  @UseInterceptors(FileInterceptor('avatar', AVATAR_UPLOAD))
+  @UseInterceptors(FileInterceptor('avatar'))
   async avatar(@CurrentUser() user: User, @UploadedFile() file: Express.Multer.File | undefined) {
     if (isDemoWriteBlocked(this.env, user.email)) {
       throw new HttpException(DEMO_WRITE_ERROR, 403);
@@ -161,6 +155,9 @@ export class AuthController {
     if (!file) {
       throw new HttpException({ error: 'No image uploaded' }, 400);
     }
+    // Commit the spooled upload to its final storage location (atomic
+    // same-volume rename) before the DB row references the final path.
+    await this.storage.put('avatars', file.filename, { tmpPath: file.path });
     return this.profile.saveAvatar(user.id, file.filename);
   }
 
diff --git a/server/src/nest/auth/auth.module.ts b/server/src/nest/auth/auth.module.ts
index 059add436..25344f8d0 100644
--- a/server/src/nest/auth/auth.module.ts
+++ b/server/src/nest/auth/auth.module.ts
@@ -18,6 +18,11 @@ import { MailerModule } from '../notifications/mailer/mailer.module';
 import { PermissionsModule } from '../permissions/permissions.module';
 import { TripMembershipModule } from '../trip-membership/trip-membership.module';
 import { EphemeralTokenModule } from './ephemeral-token.module';
+import { MulterModule } from '@nestjs/platform-express';
+import { StorageModule } from '../storage/storage.module';
+import { StorageService } from '../storage/storage.service';
+import { buildStorageUploadOptions } from '../storage/storage-upload.factory';
+import { AVATAR_FILE_FILTER, MAX_AVATAR_SIZE } from './auth.controller';
 
 /**
  * Auth module — public flows (login/register/reset/mfa-verify/logout) and the
@@ -43,7 +48,19 @@ import { EphemeralTokenModule } from './ephemeral-token.module';
  * through auth.bridge.ts.
  */
 @Module({
-  imports: [EphemeralTokenModule, RateLimitModule, AuditModule, PermissionsModule, TripMembershipModule, MailerModule, AppConfigModule, TokensModule, BudgetModule],
+  imports: [
+    MulterModule.registerAsync({
+      imports: [StorageModule],
+      inject: [StorageService],
+      useFactory: (storage: StorageService) =>
+        buildStorageUploadOptions(storage, {
+          category: 'avatars',
+          maxSize: MAX_AVATAR_SIZE,
+          fileFilter: AVATAR_FILE_FILTER,
+        }),
+    }),
+    StorageModule,
+    EphemeralTokenModule, RateLimitModule, AuditModule, PermissionsModule, TripMembershipModule, MailerModule, AppConfigModule, TokensModule, BudgetModule],
   controllers: [AuthPublicController, AuthController, PasskeyController],
   providers: [AuthService, UserProfileService, RegistrationInvitesService, PasskeyService, UserCleanupService, WebauthnConfigService, AuthMcp],
   exports: [AuthService, RegistrationInvitesService, PasskeyService, UserCleanupService],
diff --git a/server/tests/integration/profile.test.ts b/server/tests/integration/profile.test.ts
index 4a71a82c0..4b79ab541 100644
--- a/server/tests/integration/profile.test.ts
+++ b/server/tests/integration/profile.test.ts
@@ -108,6 +108,32 @@ describe('Avatar', () => {
     expect(typeof res.body.avatar_url).toBe('string');
   });
 
+  it('PROFILE-P01 — avatar bytes land at uploads/avatars under a bare uuid name', async () => {
+    const fsMod = require('fs') as typeof import('fs');
+    const pathMod = require('path') as typeof import('path');
+    const avatarsDir = pathMod.join(__dirname, '../../uploads/avatars');
+    const { user } = createUser(testDb);
+
+    const res = await request(app)
+      .post('/api/auth/avatar')
+      .set('Cookie', authCookie(user.id))
+      .attach('avatar', FIXTURE_JPEG);
+    expect(res.status).toBe(200);
+    const first = pathMod.basename(res.body.avatar_url);
+    expect(first).toMatch(/^[0-9a-f-]{36}\.jpg$/);
+    expect(fsMod.existsSync(pathMod.join(avatarsDir, first))).toBe(true);
+
+    // Re-upload removes the previous file (saveAvatar's cleanup branch).
+    const second = await request(app)
+      .post('/api/auth/avatar')
+      .set('Cookie', authCookie(user.id))
+      .attach('avatar', FIXTURE_JPEG);
+    expect(second.status).toBe(200);
+    const secondName = pathMod.basename(second.body.avatar_url);
+    expect(fsMod.existsSync(pathMod.join(avatarsDir, secondName))).toBe(true);
+    expect(fsMod.existsSync(pathMod.join(avatarsDir, first))).toBe(false);
+  });
+
   it('PROFILE-003 — uploading non-image (PDF) is rejected', async () => {
     const { user } = createUser(testDb);
     const res = await request(app)
diff --git a/server/tests/unit/nest/auth.controller.test.ts b/server/tests/unit/nest/auth.controller.test.ts
index 23a26b742..6f8578e26 100644
--- a/server/tests/unit/nest/auth.controller.test.ts
+++ b/server/tests/unit/nest/auth.controller.test.ts
@@ -35,8 +35,9 @@ const audit = { writeAudit } as unknown as AuditService;
 const apc = (a: AuthService, limiter: RateLimitService) => new AuthPublicController(a, limiter, audit);
 // Tokens moved to TokenService; the controller takes it second. Stubbed via a
 // third, optional argument so every non-token call site stays as it was.
+const storageStub = { put: vi.fn().mockResolvedValue(undefined) } as unknown as import('../../../src/nest/storage/storage.service').StorageService;
 const ac = (a: AuthService, limiter: RateLimitService, t: Partial<TokenService> = {}, pr: Partial<UserProfileService> = {}) =>
-  new AuthController(a, pr as UserProfileService, t as TokenService, limiter, audit, new RuntimeEnvService());
+  new AuthController(a, pr as UserProfileService, t as TokenService, limiter, audit, new RuntimeEnvService(), storageStub);
 
 function thrown(fn: () => unknown): { status: number; body: unknown } {
   try { fn(); } catch (err) {