From b8de469f3711fcc3e30cba901f01dd78f1f3c0fe Mon Sep 17 00:00:00 2001
From: Paul Rastoin <45004772+prastoin@users.noreply.github.com>
Date: Tue, 26 May 2026 17:10:52 +0200
Subject: [PATCH] Refactor and centralize file mimeType integrity check and
 sanitization (#20889)

# Introduction
closes https://github.com/twentyhq/private-issues/issues/484

This PR refactors the writeFile API to never expect to be passed a
mimetype, its extract is done programmatically low level so any callers
will pass through
Same for the file sanitization

## IANA override
Disclaimer for consistency we existing behavior we wanted to always have
`application/typescript`
- should we rather consider fallbacking to octect-steam instead ?
- Any pulbic assets that has .ts will now also fallback to
`application/typescript` instead of the official IANA

## Integration
Added coverage
---
 .../application-development.resolver.ts       |   5 +-
 .../application-install.service.ts            |  11 +-
 .../application-tarball.service.ts            |   1 -
 .../application/application.service.ts        |   2 -
 .../file-storage-exception-filter.spec.ts     |  36 +++
 .../__tests__/file-storage.service.spec.ts    | 137 +++++++++++-
 .../file-storage-exception-filter.ts          |  29 +++
 .../file-storage/file-storage.module.ts       |  11 +-
 .../file-storage/file-storage.service.ts      |  43 ++--
 ...are-file-for-storage-or-throw.util.spec.ts | 207 ++++++++++++++++++
 .../prepare-file-for-storage-or-throw.util.ts |  33 +++
 .../constants/twenty-mime-policy.constant.ts  |  19 ++
 .../services/file-ai-chat.service.ts          |  11 +-
 .../services/file-core-picture.service.ts     |   9 +-
 .../services/file-email-attachment.service.ts |  10 +-
 .../services/file-workflow.service.ts         |  10 +-
 .../services/files-field.service.ts           |  10 +-
 ... extract-file-info-or-throw.utils.spec.ts} |  30 ++-
 ...ts => extract-file-info-or-throw.utils.ts} |  29 ++-
 .../logic-function-resource.service.ts        |   4 -
 .../sdk-client-generation.service.ts          |   1 -
 .../code-interpreter-tool.ts                  |   1 -
 .../data/services/dev-seeder-data.service.ts  |   1 -
 .../prefill-front-component.service.ts        |   2 -
 ...ile-mime-mismatch.integration-spec.ts.snap |  37 ++++
 ...ts-controller-download.integration-spec.ts |   9 +-
 ...ion-file-mime-mismatch.integration-spec.ts | 136 ++++++++++++
 ...ts-controller-download.integration-spec.ts |   4 +-
 ...-file-svg-sanitization.integration-spec.ts | 126 +++++++++++
 ...pload-application-file.integration-spec.ts | 136 ++++++++----
 30 files changed, 958 insertions(+), 142 deletions(-)
 create mode 100644 packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage-exception-filter.spec.ts
 create mode 100644 packages/twenty-server/src/engine/core-modules/file-storage/file-storage-exception-filter.ts
 create mode 100644 packages/twenty-server/src/engine/core-modules/file-storage/utils/__tests__/prepare-file-for-storage-or-throw.util.spec.ts
 create mode 100644 packages/twenty-server/src/engine/core-modules/file-storage/utils/prepare-file-for-storage-or-throw.util.ts
 create mode 100644 packages/twenty-server/src/engine/core-modules/file/constants/twenty-mime-policy.constant.ts
 rename packages/twenty-server/src/engine/core-modules/file/utils/__tests__/{extract-file-info.utils.spec.ts => extract-file-info-or-throw.utils.spec.ts} (73%)
 rename packages/twenty-server/src/engine/core-modules/file/utils/{extract-file-info.utils.ts => extract-file-info-or-throw.utils.ts} (62%)
 create mode 100644 packages/twenty-server/test/integration/metadata/suites/application/__snapshots__/failing-upload-application-file-mime-mismatch.integration-spec.ts.snap
 create mode 100644 packages/twenty-server/test/integration/metadata/suites/application/failing-upload-application-file-mime-mismatch.integration-spec.ts
 create mode 100644 packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file-svg-sanitization.integration-spec.ts

diff --git a/packages/twenty-server/src/engine/core-modules/application/application-development/application-development.resolver.ts b/packages/twenty-server/src/engine/core-modules/application/application-development/application-development.resolver.ts
index 6495b0ae34..8d4110a1e1 100644
--- a/packages/twenty-server/src/engine/core-modules/application/application-development/application-development.resolver.ts
+++ b/packages/twenty-server/src/engine/core-modules/application/application-development/application-development.resolver.ts
@@ -20,7 +20,6 @@ import { DevelopmentApplicationDTO } from 'src/engine/core-modules/application/a
 import { GenerateApplicationTokenInput } from 'src/engine/core-modules/application/application-development/dtos/generate-application-token.input';
 import { UploadApplicationFileInput } from 'src/engine/core-modules/application/application-development/dtos/upload-application-file.input';
 import { WorkspaceMigrationDTO } from 'src/engine/core-modules/application/application-development/dtos/workspace-migration.dto';
-import { validateFilePath } from 'src/engine/core-modules/file-storage/utils/validate-file-path.util';
 import { ApplicationExceptionFilter } from 'src/engine/core-modules/application/application-exception-filter';
 import { ApplicationSyncService } from 'src/engine/core-modules/application/application-manifest/application-sync.service';
 import { resolveManifestAssetUrls } from 'src/engine/core-modules/application/application-marketplace/utils/resolve-manifest-asset-urls.util';
@@ -35,6 +34,7 @@ import {
 import { ApplicationService } from 'src/engine/core-modules/application/application.service';
 import { ApplicationTokenService } from 'src/engine/core-modules/auth/token/services/application-token.service';
 import { FileStorageService } from 'src/engine/core-modules/file-storage/file-storage.service';
+import { validateFilePath } from 'src/engine/core-modules/file-storage/utils/validate-file-path.util';
 import { FileDTO } from 'src/engine/core-modules/file/dtos/file.dto';
 import { ResolverValidationPipe } from 'src/engine/core-modules/graphql/pipes/resolver-validation.pipe';
 import { SdkClientGenerationService } from 'src/engine/core-modules/sdk-client/sdk-client-generation.service';
@@ -192,7 +192,7 @@ export class ApplicationDevelopmentResolver {
   async uploadApplicationFile(
     @AuthWorkspace() { id: workspaceId }: WorkspaceEntity,
     @Args({ name: 'file', type: () => GraphQLUpload })
-    { createReadStream, mimetype }: FileUpload,
+    { createReadStream }: FileUpload,
     @Args()
     {
       applicationUniversalIdentifier,
@@ -250,7 +250,6 @@ export class ApplicationDevelopmentResolver {
 
     return await this.fileStorageService.writeFile({
       sourceFile: buffer,
-      mimeType: mimetype,
       fileFolder,
       applicationUniversalIdentifier,
       workspaceId,
diff --git a/packages/twenty-server/src/engine/core-modules/application/application-install/application-install.service.ts b/packages/twenty-server/src/engine/core-modules/application/application-install/application-install.service.ts
index 3c3d17094c..4117963051 100644
--- a/packages/twenty-server/src/engine/core-modules/application/application-install/application-install.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/application/application-install/application-install.service.ts
@@ -5,8 +5,6 @@ import { promises as fs } from 'fs';
 import { resolve } from 'path';
 
 import semver from 'semver';
-import { extractFileInfo } from 'src/engine/core-modules/file/utils/extract-file-info.utils';
-import { sanitizeFile } from 'src/engine/core-modules/file/utils/sanitize-file.utils';
 import { Manifest } from 'twenty-shared/application';
 import { FileFolder } from 'twenty-shared/types';
 import { isDefined } from 'twenty-shared/utils';
@@ -493,15 +491,8 @@ export class ApplicationInstallService {
         );
       }
 
-      const { mimeType, ext } = await extractFileInfo({
-        file: content,
-        filename: relativePath,
-      });
-      const sanitizedContent = sanitizeFile({ file: content, ext, mimeType });
-
       await this.fileStorageService.writeFile({
-        sourceFile: sanitizedContent,
-        mimeType,
+        sourceFile: content,
         fileFolder,
         applicationUniversalIdentifier,
         workspaceId,
diff --git a/packages/twenty-server/src/engine/core-modules/application/application-registration/application-tarball.service.ts b/packages/twenty-server/src/engine/core-modules/application/application-registration/application-tarball.service.ts
index f2ab940d41..718ba0c583 100644
--- a/packages/twenty-server/src/engine/core-modules/application/application-registration/application-tarball.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/application/application-registration/application-tarball.service.ts
@@ -190,7 +190,6 @@ export class ApplicationTarballService {
       const savedFile = await this.fileStorageService.writeFile({
         sourceFile: params.tarballBuffer,
         resourcePath: `${appRegistration.id}/app.tar.gz`,
-        mimeType: 'application/gzip',
         fileFolder: FileFolder.AppTarball,
         applicationUniversalIdentifier:
           workspaceCustomFlatApplication.universalIdentifier,
diff --git a/packages/twenty-server/src/engine/core-modules/application/application.service.ts b/packages/twenty-server/src/engine/core-modules/application/application.service.ts
index aa0399f24c..335935d2e4 100644
--- a/packages/twenty-server/src/engine/core-modules/application/application.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/application/application.service.ts
@@ -411,7 +411,6 @@ export class ApplicationService {
 
     const packageJsonFile = await this.fileStorageService.writeFile({
       sourceFile: defaultPackageFields.packageJsonContent,
-      mimeType: undefined,
       fileFolder: FileFolder.Dependencies,
       applicationUniversalIdentifier: application.universalIdentifier,
       workspaceId: application.workspaceId,
@@ -422,7 +421,6 @@ export class ApplicationService {
 
     const yarnLockFile = await this.fileStorageService.writeFile({
       sourceFile: defaultPackageFields.yarnLockContent,
-      mimeType: undefined,
       fileFolder: FileFolder.Dependencies,
       applicationUniversalIdentifier: application.universalIdentifier,
       workspaceId: application.workspaceId,
diff --git a/packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage-exception-filter.spec.ts b/packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage-exception-filter.spec.ts
new file mode 100644
index 0000000000..f8d31cee6a
--- /dev/null
+++ b/packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage-exception-filter.spec.ts
@@ -0,0 +1,36 @@
+import { FileStorageExceptionFilter } from 'src/engine/core-modules/file-storage/file-storage-exception-filter';
+import {
+  FileStorageException,
+  FileStorageExceptionCode,
+} from 'src/engine/core-modules/file-storage/interfaces/file-storage-exception';
+import {
+  ForbiddenError,
+  NotFoundError,
+  UserInputError,
+} from 'src/engine/core-modules/graphql/utils/graphql-errors.util';
+
+describe('FileStorageExceptionFilter', () => {
+  const filter = new FileStorageExceptionFilter();
+
+  it.each([
+    {
+      code: FileStorageExceptionCode.INVALID_EXTENSION,
+      expectedError: UserInputError,
+    },
+    {
+      code: FileStorageExceptionCode.ACCESS_DENIED,
+      expectedError: ForbiddenError,
+    },
+    {
+      code: FileStorageExceptionCode.FILE_NOT_FOUND,
+      expectedError: NotFoundError,
+    },
+  ])(
+    'should map $code to the expected GraphQL error',
+    ({ code, expectedError }) => {
+      const exception = new FileStorageException('test message', code);
+
+      expect(() => filter.catch(exception)).toThrow(expectedError);
+    },
+  );
+});
diff --git a/packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage.service.spec.ts b/packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage.service.spec.ts
index 39fcbd04f4..851ecbc90c 100644
--- a/packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage.service.spec.ts
+++ b/packages/twenty-server/src/engine/core-modules/file-storage/__tests__/file-storage.service.spec.ts
@@ -381,7 +381,6 @@ describe('FileStorageService', () => {
               ...validResourceIdentifier,
               resourcePath: context.resourcePath,
               sourceFile: Buffer.from('malicious'),
-              mimeType: 'application/javascript',
               settings: { isTemporaryFile: false, toDelete: false },
             }),
           ).rejects.toMatchObject({
@@ -396,7 +395,6 @@ describe('FileStorageService', () => {
         await service.writeFile({
           ...validResourceIdentifier,
           sourceFile: Buffer.from('valid content'),
-          mimeType: 'application/javascript',
           settings: { isTemporaryFile: false, toDelete: false },
         });
 
@@ -406,6 +404,141 @@ describe('FileStorageService', () => {
           }),
         );
       });
+
+      describe('magic-byte backstop', () => {
+        const pngBuffer = Buffer.from([
+          0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00,
+          0x0d, 0x49, 0x48, 0x44, 0x52,
+        ]);
+        const textBuffer = Buffer.from('Hello, world!', 'utf-8');
+
+        it('should reject buffer whose magic bytes do not match the path extension', async () => {
+          await expect(
+            service.writeFile({
+              workspaceId: 'workspace-123',
+              applicationUniversalIdentifier: 'app-456',
+              fileFolder: FileFolder.PublicAsset,
+              resourcePath: 'assets/fake-image.png',
+              sourceFile: textBuffer,
+              settings: { isTemporaryFile: false, toDelete: false },
+            }),
+          ).rejects.toMatchObject({
+            code: FileStorageExceptionCode.INVALID_EXTENSION,
+          });
+
+          expect(mockDriver.writeFile).not.toHaveBeenCalled();
+        });
+
+        it('should accept buffer whose magic bytes match the path extension and persist the bytes-derived mime', async () => {
+          await service.writeFile({
+            workspaceId: 'workspace-123',
+            applicationUniversalIdentifier: 'app-456',
+            fileFolder: FileFolder.PublicAsset,
+            resourcePath: 'assets/photo.png',
+            sourceFile: pngBuffer,
+            settings: { isTemporaryFile: false, toDelete: false },
+          });
+
+          expect(mockDriver.writeFile).toHaveBeenCalledWith(
+            expect.objectContaining({ mimeType: 'image/png' }),
+          );
+          expect(mockFileRepository.upsert).toHaveBeenCalledWith(
+            expect.objectContaining({ mimeType: 'image/png' }),
+            expect.anything(),
+          );
+        });
+
+        it('should persist application/typescript for a TypeScript source string (TWENTY_MIME_POLICY)', async () => {
+          await service.writeFile({
+            workspaceId: 'workspace-123',
+            applicationUniversalIdentifier: 'app-456',
+            fileFolder: FileFolder.Source,
+            resourcePath: 'src/index.tsx',
+            sourceFile: 'export const App = () => null;',
+            settings: { isTemporaryFile: false, toDelete: false },
+          });
+
+          expect(mockDriver.writeFile).toHaveBeenCalledWith(
+            expect.objectContaining({ mimeType: 'application/typescript' }),
+          );
+        });
+
+        it('should persist application/typescript for a TypeScript source buffer (policy beats mrmime collision)', async () => {
+          await service.writeFile({
+            workspaceId: 'workspace-123',
+            applicationUniversalIdentifier: 'app-456',
+            fileFolder: FileFolder.Source,
+            resourcePath: 'src/handler.ts',
+            sourceFile: Buffer.from(
+              'export const handler = () => null;',
+              'utf-8',
+            ),
+            settings: { isTemporaryFile: false, toDelete: false },
+          });
+
+          expect(mockDriver.writeFile).toHaveBeenCalledWith(
+            expect.objectContaining({ mimeType: 'application/typescript' }),
+          );
+        });
+      });
+
+      describe('SVG sanitization (centralized invariant)', () => {
+        const maliciousSvg =
+          '<svg xmlns="http://www.w3.org/2000/svg" onload="alert(1)"><script>alert(2)</script><circle r="10" /></svg>';
+
+        it('should strip scripts and event handlers from an SVG string upload', async () => {
+          await service.writeFile({
+            workspaceId: 'workspace-123',
+            applicationUniversalIdentifier: 'app-456',
+            fileFolder: FileFolder.PublicAsset,
+            resourcePath: 'assets/icon.svg',
+            sourceFile: maliciousSvg,
+            settings: { isTemporaryFile: false, toDelete: false },
+          });
+
+          const driverCall = mockDriver.writeFile.mock.calls[0][0];
+
+          expect(driverCall.mimeType).toBe('image/svg+xml');
+          expect(typeof driverCall.sourceFile).toBe('string');
+          expect(driverCall.sourceFile).not.toContain('<script>');
+          expect(driverCall.sourceFile).not.toContain('onload');
+          expect(driverCall.sourceFile).toContain('<circle');
+        });
+
+        it('should strip scripts and event handlers from an SVG buffer upload', async () => {
+          await service.writeFile({
+            workspaceId: 'workspace-123',
+            applicationUniversalIdentifier: 'app-456',
+            fileFolder: FileFolder.PublicAsset,
+            resourcePath: 'assets/icon.svg',
+            sourceFile: Buffer.from(maliciousSvg, 'utf-8'),
+            settings: { isTemporaryFile: false, toDelete: false },
+          });
+
+          const driverCall = mockDriver.writeFile.mock.calls[0][0];
+
+          expect(driverCall.mimeType).toBe('image/svg+xml');
+          expect(driverCall.sourceFile).not.toContain('<script>');
+          expect(driverCall.sourceFile).not.toContain('onload');
+        });
+
+        it('should leave non-SVG content untouched (sanitize is no-op)', async () => {
+          const original = '{"foo": "bar"}';
+
+          await service.writeFile({
+            workspaceId: 'workspace-123',
+            applicationUniversalIdentifier: 'app-456',
+            fileFolder: FileFolder.Source,
+            resourcePath: 'package.json',
+            sourceFile: original,
+            settings: { isTemporaryFile: false, toDelete: false },
+          });
+
+          const driverCall = mockDriver.writeFile.mock.calls[0][0];
+
+          expect(driverCall.sourceFile).toBe(original);
+        });
+      });
     });
 
     describe('deleteFile', () => {
diff --git a/packages/twenty-server/src/engine/core-modules/file-storage/file-storage-exception-filter.ts b/packages/twenty-server/src/engine/core-modules/file-storage/file-storage-exception-filter.ts
new file mode 100644
index 0000000000..31095cd551
--- /dev/null
+++ b/packages/twenty-server/src/engine/core-modules/file-storage/file-storage-exception-filter.ts
@@ -0,0 +1,29 @@
+import { Catch, ExceptionFilter } from '@nestjs/common';
+
+import { assertUnreachable } from 'twenty-shared/utils';
+
+import {
+  FileStorageException,
+  FileStorageExceptionCode,
+} from 'src/engine/core-modules/file-storage/interfaces/file-storage-exception';
+import {
+  ForbiddenError,
+  NotFoundError,
+  UserInputError,
+} from 'src/engine/core-modules/graphql/utils/graphql-errors.util';
+
+@Catch(FileStorageException)
+export class FileStorageExceptionFilter implements ExceptionFilter {
+  catch(exception: FileStorageException) {
+    switch (exception.code) {
+      case FileStorageExceptionCode.INVALID_EXTENSION:
+        throw new UserInputError(exception);
+      case FileStorageExceptionCode.ACCESS_DENIED:
+        throw new ForbiddenError(exception);
+      case FileStorageExceptionCode.FILE_NOT_FOUND:
+        throw new NotFoundError(exception);
+      default:
+        assertUnreachable(exception.code);
+    }
+  }
+}
diff --git a/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.module.ts b/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.module.ts
index 1bbf279c0b..8cf4745ead 100644
--- a/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.module.ts
+++ b/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.module.ts
@@ -1,7 +1,9 @@
 import { type DynamicModule, Global } from '@nestjs/common';
+import { APP_FILTER } from '@nestjs/core';
 import { TypeOrmModule } from '@nestjs/typeorm';
 
 import { ApplicationEntity } from 'src/engine/core-modules/application/application.entity';
+import { FileStorageExceptionFilter } from 'src/engine/core-modules/file-storage/file-storage-exception-filter';
 import { FileStorageDriverFactory } from 'src/engine/core-modules/file-storage/file-storage-driver.factory';
 import { FileStorageService } from 'src/engine/core-modules/file-storage/file-storage.service';
 import { FileEntity } from 'src/engine/core-modules/file/entities/file.entity';
@@ -16,7 +18,14 @@ export class FileStorageModule {
         TwentyConfigModule,
         TypeOrmModule.forFeature([FileEntity, ApplicationEntity]),
       ],
-      providers: [FileStorageDriverFactory, FileStorageService],
+      providers: [
+        FileStorageDriverFactory,
+        FileStorageService,
+        {
+          provide: APP_FILTER,
+          useClass: FileStorageExceptionFilter,
+        },
+      ],
       exports: [FileStorageDriverFactory, FileStorageService],
     };
   }
diff --git a/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.service.ts b/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.service.ts
index 85eb6a47a8..f716ed9ecb 100644
--- a/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/file-storage/file-storage.service.ts
@@ -13,6 +13,7 @@ import {
   FileStorageException,
   FileStorageExceptionCode,
 } from 'src/engine/core-modules/file-storage/interfaces/file-storage-exception';
+import { prepareFileForStorageOrThrow } from 'src/engine/core-modules/file-storage/utils/prepare-file-for-storage-or-throw.util';
 import { validateFilePath } from 'src/engine/core-modules/file-storage/utils/validate-file-path.util';
 import { validateFolderPath } from 'src/engine/core-modules/file-storage/utils/validate-folder-path.util';
 import { validateStoragePathIsWithinWorkspaceOrThrow } from 'src/engine/core-modules/file-storage/utils/validate-storage-path-is-within-workspace-or-throw.util';
@@ -66,7 +67,7 @@ export class FileStorageService {
     return { onStoragePath, resourcePath };
   }
 
-  private validateAndBuildFileStoragePath(params: ResourceIdentifier): {
+  private validateAndBuildFileStoragePathOrThrow(params: ResourceIdentifier): {
     onStorageFilePath: string;
     filePath: string;
   } {
@@ -91,7 +92,7 @@ export class FileStorageService {
     return { onStorageFilePath: onStoragePath, filePath: resourcePath };
   }
 
-  private validateAndBuildFolderStoragePath(
+  private validateAndBuildFolderStoragePathOrThrow(
     params: Omit<ResourceIdentifier, 'resourcePath'> & { folderPath: string },
   ): { onStorageFolderPath: string; folderPath: string } {
     const validationResult = validateFolderPath({
@@ -119,7 +120,6 @@ export class FileStorageService {
 
   async writeFile({
     sourceFile,
-    mimeType,
     fileFolder,
     applicationUniversalIdentifier,
     workspaceId,
@@ -129,7 +129,6 @@ export class FileStorageService {
     queryRunner,
   }: ResourceIdentifier & {
     sourceFile: string | Buffer | Uint8Array;
-    mimeType: string | undefined;
     fileId?: string;
     settings: FileSettings;
     queryRunner?: QueryRunner;
@@ -151,17 +150,23 @@ export class FileStorageService {
     });
 
     const { onStorageFilePath, filePath } =
-      this.validateAndBuildFileStoragePath({
+      this.validateAndBuildFileStoragePathOrThrow({
         workspaceId,
         applicationUniversalIdentifier,
         fileFolder,
         resourcePath,
       });
 
+    const { sourceFile: persistedSourceFile, mimeType } =
+      await prepareFileForStorageOrThrow({
+        sourceFile,
+        resourcePath,
+      });
+
     await driver.writeFile({
       filePath: onStorageFilePath,
       mimeType,
-      sourceFile,
+      sourceFile: persistedSourceFile,
     });
 
     await fileRepository.upsert(
@@ -172,9 +177,9 @@ export class FileStorageService {
         id: fileId,
         mimeType,
         size:
-          typeof sourceFile === 'string'
-            ? Buffer.byteLength(sourceFile)
-            : sourceFile.length,
+          typeof persistedSourceFile === 'string'
+            ? Buffer.byteLength(persistedSourceFile)
+            : persistedSourceFile.length,
         settings,
       },
       ['path', 'workspaceId', 'applicationId'],
@@ -197,7 +202,8 @@ export class FileStorageService {
     },
   ): Promise<string | null> {
     const driver = this.fileStorageDriverFactory.getCurrentDriver();
-    const { onStorageFilePath } = this.validateAndBuildFileStoragePath(params);
+    const { onStorageFilePath } =
+      this.validateAndBuildFileStoragePathOrThrow(params);
 
     return driver.getPresignedUrl({
       filePath: onStorageFilePath,
@@ -210,7 +216,8 @@ export class FileStorageService {
   readFile(params: ResourceIdentifier): Promise<Readable> {
     const driver = this.fileStorageDriverFactory.getCurrentDriver();
 
-    const { onStorageFilePath } = this.validateAndBuildFileStoragePath(params);
+    const { onStorageFilePath } =
+      this.validateAndBuildFileStoragePathOrThrow(params);
 
     return driver.readFile({ filePath: onStorageFilePath });
   }
@@ -219,7 +226,8 @@ export class FileStorageService {
     params: ResourceIdentifier & { localPath: string },
   ): Promise<void> {
     const driver = this.fileStorageDriverFactory.getCurrentDriver();
-    const { onStorageFilePath } = this.validateAndBuildFileStoragePath(params);
+    const { onStorageFilePath } =
+      this.validateAndBuildFileStoragePathOrThrow(params);
 
     return driver.downloadFile({
       onStoragePath: onStorageFilePath,
@@ -256,7 +264,7 @@ export class FileStorageService {
   async deleteFile(params: ResourceIdentifier): Promise<void> {
     const driver = this.fileStorageDriverFactory.getCurrentDriver();
     const { onStorageFilePath, filePath } =
-      this.validateAndBuildFileStoragePath(params);
+      this.validateAndBuildFileStoragePathOrThrow(params);
 
     await driver.delete({
       folderPath: dirname(onStorageFilePath),
@@ -288,7 +296,7 @@ export class FileStorageService {
     } = params;
 
     const { onStorageFolderPath, folderPath: validatedFolderPath } =
-      this.validateAndBuildFolderStoragePath({
+      this.validateAndBuildFolderStoragePathOrThrow({
         workspaceId,
         applicationUniversalIdentifier,
         fileFolder,
@@ -373,9 +381,9 @@ export class FileStorageService {
     const driver = this.fileStorageDriverFactory.getCurrentDriver();
 
     const { onStorageFilePath: fromPath } =
-      this.validateAndBuildFileStoragePath(from);
+      this.validateAndBuildFileStoragePathOrThrow(from);
     const { onStorageFilePath: toPath } =
-      this.validateAndBuildFileStoragePath(to);
+      this.validateAndBuildFileStoragePathOrThrow(to);
 
     const isFile = await driver.checkFileExists({ filePath: fromPath });
 
@@ -394,7 +402,8 @@ export class FileStorageService {
 
   checkFileExists(params: ResourceIdentifier): Promise<boolean> {
     const driver = this.fileStorageDriverFactory.getCurrentDriver();
-    const { onStorageFilePath } = this.validateAndBuildFileStoragePath(params);
+    const { onStorageFilePath } =
+      this.validateAndBuildFileStoragePathOrThrow(params);
 
     return driver.checkFileExists({ filePath: onStorageFilePath });
   }
diff --git a/packages/twenty-server/src/engine/core-modules/file-storage/utils/__tests__/prepare-file-for-storage-or-throw.util.spec.ts b/packages/twenty-server/src/engine/core-modules/file-storage/utils/__tests__/prepare-file-for-storage-or-throw.util.spec.ts
new file mode 100644
index 0000000000..aa1b720f2f
--- /dev/null
+++ b/packages/twenty-server/src/engine/core-modules/file-storage/utils/__tests__/prepare-file-for-storage-or-throw.util.spec.ts
@@ -0,0 +1,207 @@
+import { FileStorageExceptionCode } from 'src/engine/core-modules/file-storage/interfaces/file-storage-exception';
+import { prepareFileForStorageOrThrow } from 'src/engine/core-modules/file-storage/utils/prepare-file-for-storage-or-throw.util';
+
+const pngBuffer = Buffer.from([
+  0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00, 0x0d, 0x49,
+  0x48, 0x44, 0x52,
+]);
+const pdfBuffer = Buffer.from('%PDF-1.4\n', 'utf-8');
+const zipBuffer = Buffer.from([0x50, 0x4b, 0x03, 0x04]);
+const textBuffer = Buffer.from('Hello, world!', 'utf-8');
+
+const benignSvg =
+  '<svg xmlns="http://www.w3.org/2000/svg"><circle r="10" /></svg>';
+const maliciousSvg = `<svg xmlns="http://www.w3.org/2000/svg" onload="alert(1)"><script>alert(2)</script><circle r="10" /></svg>`;
+
+describe('prepareFileForStorageOrThrow', () => {
+  describe('mime resolution', () => {
+    it.each([
+      {
+        name: 'TypeScript .ts string (policy)',
+        sourceFile: 'export const x = 1;',
+        resourcePath: 'src/index.ts',
+        expectedMime: 'application/typescript',
+      },
+      {
+        name: 'TypeScript .tsx string (policy)',
+        sourceFile: 'export const App = () => null;',
+        resourcePath: 'src/App.tsx',
+        expectedMime: 'application/typescript',
+      },
+      {
+        name: '.mjs string (mrmime)',
+        sourceFile: 'export default 1;',
+        resourcePath: 'src/handler.mjs',
+        expectedMime: 'text/javascript',
+      },
+      {
+        name: 'JSON string (mrmime)',
+        sourceFile: '{"foo": "bar"}',
+        resourcePath: 'package.json',
+        expectedMime: 'application/json',
+      },
+      {
+        name: 'unknown-extension string (octet-stream)',
+        sourceFile: 'lock content',
+        resourcePath: 'yarn.lock',
+        expectedMime: 'application/octet-stream',
+      },
+      {
+        name: 'no-extension string (octet-stream)',
+        sourceFile: 'content',
+        resourcePath: 'somefile',
+        expectedMime: 'application/octet-stream',
+      },
+      {
+        name: 'dot-file string (octet-stream — extname semantics)',
+        sourceFile: 'content',
+        resourcePath: '.gitignore',
+        expectedMime: 'application/octet-stream',
+      },
+    ])(
+      'returns $expectedMime for $name',
+      async ({ sourceFile, resourcePath, expectedMime }) => {
+        const { mimeType } = await prepareFileForStorageOrThrow({
+          sourceFile,
+          resourcePath,
+        });
+
+        expect(mimeType).toBe(expectedMime);
+      },
+    );
+
+    it.each([
+      {
+        name: 'PNG buffer',
+        sourceFile: pngBuffer,
+        resourcePath: 'images/photo.png',
+        expectedMime: 'image/png',
+      },
+      {
+        name: 'PDF buffer',
+        sourceFile: pdfBuffer,
+        resourcePath: 'docs/contract.pdf',
+        expectedMime: 'application/pdf',
+      },
+      {
+        name: 'ZIP buffer',
+        sourceFile: zipBuffer,
+        resourcePath: 'archives/data.zip',
+        expectedMime: 'application/zip',
+      },
+    ])(
+      'returns the bytes-derived mime for $name',
+      async ({ sourceFile, resourcePath, expectedMime }) => {
+        const { mimeType } = await prepareFileForStorageOrThrow({
+          sourceFile,
+          resourcePath,
+        });
+
+        expect(mimeType).toBe(expectedMime);
+      },
+    );
+
+    it('returns the bytes-derived mime for a Uint8Array source', async () => {
+      const { mimeType } = await prepareFileForStorageOrThrow({
+        sourceFile: new Uint8Array(pngBuffer),
+        resourcePath: 'images/photo.png',
+      });
+
+      expect(mimeType).toBe('image/png');
+    });
+  });
+
+  describe('binary-extension backstop', () => {
+    it('throws when a buffer with a binary extension does not match the magic bytes', async () => {
+      await expect(
+        prepareFileForStorageOrThrow({
+          sourceFile: textBuffer,
+          resourcePath: 'fake-image.png',
+        }),
+      ).rejects.toMatchObject({
+        code: FileStorageExceptionCode.INVALID_EXTENSION,
+      });
+    });
+
+    it('throws when a string with a binary extension does not match the magic bytes', async () => {
+      await expect(
+        prepareFileForStorageOrThrow({
+          sourceFile: 'this is not a png',
+          resourcePath: 'fake-image.png',
+        }),
+      ).rejects.toMatchObject({
+        code: FileStorageExceptionCode.INVALID_EXTENSION,
+      });
+    });
+
+    it('throws on Uint8Array byte/extension mismatch', async () => {
+      await expect(
+        prepareFileForStorageOrThrow({
+          sourceFile: new Uint8Array(textBuffer),
+          resourcePath: 'fake-image.pdf',
+        }),
+      ).rejects.toMatchObject({
+        code: FileStorageExceptionCode.INVALID_EXTENSION,
+      });
+    });
+  });
+
+  describe('SVG sanitization', () => {
+    it('sanitizes an SVG string by removing scripts and event handlers', async () => {
+      const { sourceFile, mimeType } = await prepareFileForStorageOrThrow({
+        sourceFile: maliciousSvg,
+        resourcePath: 'assets/icon.svg',
+      });
+
+      expect(mimeType).toBe('image/svg+xml');
+      expect(typeof sourceFile).toBe('string');
+      expect(sourceFile).not.toContain('<script>');
+      expect(sourceFile).not.toContain('onload');
+      expect(sourceFile).toContain('<circle');
+    });
+
+    it('sanitizes an SVG buffer (DOMPurify returns a string)', async () => {
+      const { sourceFile, mimeType } = await prepareFileForStorageOrThrow({
+        sourceFile: Buffer.from(maliciousSvg, 'utf-8'),
+        resourcePath: 'assets/icon.svg',
+      });
+
+      expect(mimeType).toBe('image/svg+xml');
+      expect(typeof sourceFile).toBe('string');
+      expect(sourceFile).not.toContain('<script>');
+      expect(sourceFile).not.toContain('onload');
+    });
+
+    it('preserves a benign SVG (no destructive sanitization)', async () => {
+      const { sourceFile } = await prepareFileForStorageOrThrow({
+        sourceFile: benignSvg,
+        resourcePath: 'assets/icon.svg',
+      });
+
+      expect(sourceFile).toContain('<circle');
+      expect(sourceFile).toContain('xmlns');
+    });
+  });
+
+  describe('non-SVG content is returned unchanged', () => {
+    it('returns the original buffer reference for a non-SVG buffer', async () => {
+      const { sourceFile } = await prepareFileForStorageOrThrow({
+        sourceFile: pngBuffer,
+        resourcePath: 'images/photo.png',
+      });
+
+      expect(sourceFile).toBe(pngBuffer);
+    });
+
+    it('returns the original string for a non-SVG string', async () => {
+      const original = '{"foo": "bar"}';
+
+      const { sourceFile } = await prepareFileForStorageOrThrow({
+        sourceFile: original,
+        resourcePath: 'package.json',
+      });
+
+      expect(sourceFile).toBe(original);
+    });
+  });
+});
diff --git a/packages/twenty-server/src/engine/core-modules/file-storage/utils/prepare-file-for-storage-or-throw.util.ts b/packages/twenty-server/src/engine/core-modules/file-storage/utils/prepare-file-for-storage-or-throw.util.ts
new file mode 100644
index 0000000000..97ade3137d
--- /dev/null
+++ b/packages/twenty-server/src/engine/core-modules/file-storage/utils/prepare-file-for-storage-or-throw.util.ts
@@ -0,0 +1,33 @@
+import { extractFileInfoOrThrow } from 'src/engine/core-modules/file/utils/extract-file-info-or-throw.utils';
+import { sanitizeFile } from 'src/engine/core-modules/file/utils/sanitize-file.utils';
+
+export const prepareFileForStorageOrThrow = async ({
+  sourceFile,
+  resourcePath,
+}: {
+  sourceFile: Buffer | Uint8Array | string;
+  resourcePath: string;
+}): Promise<{
+  sourceFile: Buffer | Uint8Array | string;
+  mimeType: string;
+}> => {
+  const bufferForExtract =
+    typeof sourceFile === 'string'
+      ? Buffer.from(sourceFile, 'utf8')
+      : Buffer.isBuffer(sourceFile)
+        ? sourceFile
+        : Buffer.from(sourceFile);
+
+  const { mimeType, ext } = await extractFileInfoOrThrow({
+    file: bufferForExtract,
+    filename: resourcePath,
+  });
+
+  const sanitizedSourceFile = sanitizeFile({
+    file: sourceFile,
+    ext,
+    mimeType,
+  });
+
+  return { sourceFile: sanitizedSourceFile, mimeType };
+};
diff --git a/packages/twenty-server/src/engine/core-modules/file/constants/twenty-mime-policy.constant.ts b/packages/twenty-server/src/engine/core-modules/file/constants/twenty-mime-policy.constant.ts
new file mode 100644
index 0000000000..ecdd2255da
--- /dev/null
+++ b/packages/twenty-server/src/engine/core-modules/file/constants/twenty-mime-policy.constant.ts
@@ -0,0 +1,19 @@
+// Extensions where Twenty intentionally deviates from the IANA-standard mime
+// mapping returned by mrmime. Twenty's storage layer persists these values
+// instead of mrmime's output (or instead of throwing in the case of `.ts`).
+//
+// Why each entry exists:
+//   - ts/tsx:    IANA registers `.ts` as `video/mp2t` (MPEG-2 Transport Stream),
+//                which predates TypeScript. `.tsx` is unregistered. Twenty uses
+//                the developer-tooling convention `application/typescript`.
+//
+// Only add an entry when (1) mrmime returns the wrong mime (collision) or no
+// mime AND (2) Twenty actually writes that extension via FileStorageService AND
+// (3) there is a clear developer-tooling convention for the right mime. For
+// everything else — media, archives, documents, `.js`, `.mjs`, `.cjs`, etc. —
+// trust mrmime. This policy is reactive: extend it the day we observe a real
+// wrong-mime persisted by an exercised code path, not in anticipation.
+export const TWENTY_MIME_POLICY: Record<string, string> = {
+  ts: 'application/typescript',
+  tsx: 'application/typescript',
+};
diff --git a/packages/twenty-server/src/engine/core-modules/file/file-ai-chat/services/file-ai-chat.service.ts b/packages/twenty-server/src/engine/core-modules/file/file-ai-chat/services/file-ai-chat.service.ts
index f637faa930..73b43a63f8 100644
--- a/packages/twenty-server/src/engine/core-modules/file/file-ai-chat/services/file-ai-chat.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/file/file-ai-chat/services/file-ai-chat.service.ts
@@ -8,8 +8,8 @@ import { ApplicationService } from 'src/engine/core-modules/application/applicat
 import { FileStorageService } from 'src/engine/core-modules/file-storage/file-storage.service';
 import { FileWithSignedUrlDTO } from 'src/engine/core-modules/file/dtos/file-with-sign-url.dto';
 import { FileUrlService } from 'src/engine/core-modules/file/file-url/file-url.service';
-import { extractFileInfo } from 'src/engine/core-modules/file/utils/extract-file-info.utils';
-import { sanitizeFile } from 'src/engine/core-modules/file/utils/sanitize-file.utils';
+import { extractFileInfoOrThrow } from 'src/engine/core-modules/file/utils/extract-file-info-or-throw.utils';
+
 @Injectable()
 export class FileAiChatService {
   constructor(
@@ -27,13 +27,11 @@ export class FileAiChatService {
     filename: string;
     workspaceId: string;
   }): Promise<FileWithSignedUrlDTO> {
-    const { mimeType, ext } = await extractFileInfo({
+    const { ext } = await extractFileInfoOrThrow({
       file,
       filename,
     });
 
-    const sanitizedFile = sanitizeFile({ file, ext, mimeType });
-
     const fileId = v4();
     const name = `${fileId}${isNonEmptyString(ext) ? `.${ext}` : ''}`;
 
@@ -45,9 +43,8 @@ export class FileAiChatService {
       );
 
     const savedFile = await this.fileStorageService.writeFile({
-      sourceFile: sanitizedFile,
+      sourceFile: file,
       resourcePath: name,
-      mimeType,
       fileFolder: FileFolder.AgentChat,
       applicationUniversalIdentifier:
         workspaceCustomFlatApplication.universalIdentifier,
diff --git a/packages/twenty-server/src/engine/core-modules/file/file-core-picture/services/file-core-picture.service.ts b/packages/twenty-server/src/engine/core-modules/file/file-core-picture/services/file-core-picture.service.ts
index 69dab2e231..74e2f7197e 100644
--- a/packages/twenty-server/src/engine/core-modules/file/file-core-picture/services/file-core-picture.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/file/file-core-picture/services/file-core-picture.service.ts
@@ -19,9 +19,8 @@ import { FileStorageService } from 'src/engine/core-modules/file-storage/file-st
 import { FileWithSignedUrlDTO } from 'src/engine/core-modules/file/dtos/file-with-sign-url.dto';
 import { FileEntity } from 'src/engine/core-modules/file/entities/file.entity';
 import { FileUrlService } from 'src/engine/core-modules/file/file-url/file-url.service';
-import { extractFileInfo } from 'src/engine/core-modules/file/utils/extract-file-info.utils';
+import { extractFileInfoOrThrow } from 'src/engine/core-modules/file/utils/extract-file-info-or-throw.utils';
 import { removeFileFolderFromFileEntityPath } from 'src/engine/core-modules/file/utils/remove-file-folder-from-file-entity-path.utils';
-import { sanitizeFile } from 'src/engine/core-modules/file/utils/sanitize-file.utils';
 import { SecureHttpClientService } from 'src/engine/core-modules/secure-http-client/secure-http-client.service';
 import { WorkspaceEntity } from 'src/engine/core-modules/workspace/workspace.entity';
 import { getImageBufferFromUrl } from 'src/utils/image';
@@ -72,8 +71,7 @@ export class FileCorePictureService {
     applicationUniversalIdentifier?: string;
     queryRunner?: QueryRunner;
   }): Promise<FileEntity> {
-    const { mimeType, ext } = await extractFileInfo({ file, filename });
-    const sanitizedFile = sanitizeFile({ file, ext, mimeType });
+    const { ext } = await extractFileInfoOrThrow({ file, filename });
 
     const fileId = v4();
     const finalName = `${fileId}${isNonEmptyString(ext) ? `.${ext}` : ''}`;
@@ -83,9 +81,8 @@ export class FileCorePictureService {
       (await this.findCustomApplicationUniversalIdentifier(workspaceId));
 
     const savedFile = await this.fileStorageService.writeFile({
-      sourceFile: sanitizedFile,
+      sourceFile: file,
       resourcePath: finalName,
-      mimeType,
       fileFolder: FileFolder.CorePicture,
       applicationUniversalIdentifier: universalIdentifier,
       workspaceId,
diff --git a/packages/twenty-server/src/engine/core-modules/file/file-email-attachment/services/file-email-attachment.service.ts b/packages/twenty-server/src/engine/core-modules/file/file-email-attachment/services/file-email-attachment.service.ts
index f84bea0516..d5138ec08f 100644
--- a/packages/twenty-server/src/engine/core-modules/file/file-email-attachment/services/file-email-attachment.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/file/file-email-attachment/services/file-email-attachment.service.ts
@@ -8,8 +8,7 @@ import { ApplicationService } from 'src/engine/core-modules/application/applicat
 import { FileStorageService } from 'src/engine/core-modules/file-storage/file-storage.service';
 import { FileWithSignedUrlDTO } from 'src/engine/core-modules/file/dtos/file-with-sign-url.dto';
 import { FileUrlService } from 'src/engine/core-modules/file/file-url/file-url.service';
-import { extractFileInfo } from 'src/engine/core-modules/file/utils/extract-file-info.utils';
-import { sanitizeFile } from 'src/engine/core-modules/file/utils/sanitize-file.utils';
+import { extractFileInfoOrThrow } from 'src/engine/core-modules/file/utils/extract-file-info-or-throw.utils';
 
 @Injectable()
 export class FileEmailAttachmentService {
@@ -30,13 +29,11 @@ export class FileEmailAttachmentService {
     filename: string;
     workspaceId: string;
   }): Promise<FileWithSignedUrlDTO> {
-    const { mimeType, ext } = await extractFileInfo({
+    const { ext } = await extractFileInfoOrThrow({
       file,
       filename,
     });
 
-    const sanitizedFile = sanitizeFile({ file, ext, mimeType });
-
     const fileId = v4();
     const name = `${fileId}${isNonEmptyString(ext) ? `.${ext}` : ''}`;
 
@@ -48,9 +45,8 @@ export class FileEmailAttachmentService {
       );
 
     const savedFile = await this.fileStorageService.writeFile({
-      sourceFile: sanitizedFile,
+      sourceFile: file,
       resourcePath: name,
-      mimeType,
       fileFolder: FileFolder.EmailAttachment,
       applicationUniversalIdentifier:
         workspaceCustomFlatApplication.universalIdentifier,
diff --git a/packages/twenty-server/src/engine/core-modules/file/file-workflow/services/file-workflow.service.ts b/packages/twenty-server/src/engine/core-modules/file/file-workflow/services/file-workflow.service.ts
index 95aa486490..852f5f5ded 100644
--- a/packages/twenty-server/src/engine/core-modules/file/file-workflow/services/file-workflow.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/file/file-workflow/services/file-workflow.service.ts
@@ -8,8 +8,7 @@ import { ApplicationService } from 'src/engine/core-modules/application/applicat
 import { FileStorageService } from 'src/engine/core-modules/file-storage/file-storage.service';
 import { FileWithSignedUrlDTO } from 'src/engine/core-modules/file/dtos/file-with-sign-url.dto';
 import { FileUrlService } from 'src/engine/core-modules/file/file-url/file-url.service';
-import { extractFileInfo } from 'src/engine/core-modules/file/utils/extract-file-info.utils';
-import { sanitizeFile } from 'src/engine/core-modules/file/utils/sanitize-file.utils';
+import { extractFileInfoOrThrow } from 'src/engine/core-modules/file/utils/extract-file-info-or-throw.utils';
 
 @Injectable()
 export class FileWorkflowService {
@@ -28,13 +27,11 @@ export class FileWorkflowService {
     filename: string;
     workspaceId: string;
   }): Promise<FileWithSignedUrlDTO> {
-    const { mimeType, ext } = await extractFileInfo({
+    const { ext } = await extractFileInfoOrThrow({
       file,
       filename,
     });
 
-    const sanitizedFile = sanitizeFile({ file, ext, mimeType });
-
     const fileId = v4();
     const name = `${fileId}${isNonEmptyString(ext) ? `.${ext}` : ''}`;
 
@@ -46,9 +43,8 @@ export class FileWorkflowService {
       );
 
     const savedFile = await this.fileStorageService.writeFile({
-      sourceFile: sanitizedFile,
+      sourceFile: file,
       resourcePath: name,
-      mimeType,
       fileFolder: FileFolder.Workflow,
       applicationUniversalIdentifier:
         workspaceCustomFlatApplication.universalIdentifier,
diff --git a/packages/twenty-server/src/engine/core-modules/file/files-field/services/files-field.service.ts b/packages/twenty-server/src/engine/core-modules/file/files-field/services/files-field.service.ts
index 4f978915df..282f701d06 100644
--- a/packages/twenty-server/src/engine/core-modules/file/files-field/services/files-field.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/file/files-field/services/files-field.service.ts
@@ -15,8 +15,7 @@ import {
   FilesFieldException,
   FilesFieldExceptionCode,
 } from 'src/engine/core-modules/file/files-field/files-field.exception';
-import { extractFileInfo } from 'src/engine/core-modules/file/utils/extract-file-info.utils';
-import { sanitizeFile } from 'src/engine/core-modules/file/utils/sanitize-file.utils';
+import { extractFileInfoOrThrow } from 'src/engine/core-modules/file/utils/extract-file-info-or-throw.utils';
 import { FieldMetadataEntity } from 'src/engine/metadata-modules/field-metadata/field-metadata.entity';
 
 @Injectable()
@@ -53,13 +52,11 @@ export class FilesFieldService {
       );
     }
 
-    const { mimeType, ext } = await extractFileInfo({
+    const { ext } = await extractFileInfoOrThrow({
       file,
       filename,
     });
 
-    const sanitizedFile = sanitizeFile({ file, ext, mimeType });
-
     const fileId = v4();
     const name = `${fileId}${isNonEmptyString(ext) ? `.${ext}` : ''}`;
 
@@ -82,9 +79,8 @@ export class FilesFieldService {
     });
 
     const savedFile = await this.fileStorageService.writeFile({
-      sourceFile: sanitizedFile,
+      sourceFile: file,
       resourcePath: `${fieldMetadata.universalIdentifier}/${name}`,
-      mimeType,
       fileFolder: FileFolder.FilesField,
       applicationUniversalIdentifier: application.universalIdentifier,
       workspaceId,
diff --git a/packages/twenty-server/src/engine/core-modules/file/utils/__tests__/extract-file-info.utils.spec.ts b/packages/twenty-server/src/engine/core-modules/file/utils/__tests__/extract-file-info-or-throw.utils.spec.ts
similarity index 73%
rename from packages/twenty-server/src/engine/core-modules/file/utils/__tests__/extract-file-info.utils.spec.ts
rename to packages/twenty-server/src/engine/core-modules/file/utils/__tests__/extract-file-info-or-throw.utils.spec.ts
index 8aa8fcf539..2132b6e284 100644
--- a/packages/twenty-server/src/engine/core-modules/file/utils/__tests__/extract-file-info.utils.spec.ts
+++ b/packages/twenty-server/src/engine/core-modules/file/utils/__tests__/extract-file-info-or-throw.utils.spec.ts
@@ -1,4 +1,4 @@
-import { extractFileInfo } from '../extract-file-info.utils';
+import { extractFileInfoOrThrow } from '../extract-file-info-or-throw.utils';
 
 const pngBuffer = Buffer.from([
   0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00, 0x0d, 0x49,
@@ -8,7 +8,7 @@ const pdfBuffer = Buffer.from('%PDF-1.4\n', 'utf-8');
 const textBuffer = Buffer.from('Hello, world!', 'utf-8');
 const zipBuffer = Buffer.from([0x50, 0x4b, 0x03, 0x04]);
 
-describe('extractFileInfo', () => {
+describe('extractFileInfoOrThrow', () => {
   it.each([
     {
       name: 'PNG',
@@ -41,7 +41,7 @@ describe('extractFileInfo', () => {
   ])(
     'should detect $name from buffer magic numbers',
     async ({ buffer, filename, ext, mime }) => {
-      const result = await extractFileInfo({ file: buffer, filename });
+      const result = await extractFileInfoOrThrow({ file: buffer, filename });
 
       expect(result).toEqual({ mimeType: mime, ext });
     },
@@ -78,7 +78,10 @@ describe('extractFileInfo', () => {
   ])(
     'should fall back to extension for $name files',
     async ({ filename, ext, mime }) => {
-      const result = await extractFileInfo({ file: textBuffer, filename });
+      const result = await extractFileInfoOrThrow({
+        file: textBuffer,
+        filename,
+      });
 
       expect(result).toEqual({ mimeType: mime, ext });
     },
@@ -95,10 +98,27 @@ describe('extractFileInfo', () => {
     'should throw when $ext extension does not match buffer content',
     async ({ filename, ext, expectedMime }) => {
       await expect(
-        extractFileInfo({ file: textBuffer, filename }),
+        extractFileInfoOrThrow({ file: textBuffer, filename }),
       ).rejects.toThrow(
         `File content does not match its extension. The file has extension '${ext}' (expected mime type: ${expectedMime}), but the file content could not be detected as this type. The file may be corrupted, have the wrong extension, or be a security risk.`,
       );
     },
   );
+
+  describe('TWENTY_MIME_POLICY (Twenty deviates from IANA)', () => {
+    it.each([
+      { filename: 'src/index.ts', expectedMime: 'application/typescript' },
+      { filename: 'src/index.tsx', expectedMime: 'application/typescript' },
+    ])(
+      'should return $expectedMime for $filename without throwing on IANA collision',
+      async ({ filename, expectedMime }) => {
+        const result = await extractFileInfoOrThrow({
+          file: textBuffer,
+          filename,
+        });
+
+        expect(result.mimeType).toBe(expectedMime);
+      },
+    );
+  });
 });
diff --git a/packages/twenty-server/src/engine/core-modules/file/utils/extract-file-info.utils.ts b/packages/twenty-server/src/engine/core-modules/file/utils/extract-file-info-or-throw.utils.ts
similarity index 62%
rename from packages/twenty-server/src/engine/core-modules/file/utils/extract-file-info.utils.ts
rename to packages/twenty-server/src/engine/core-modules/file/utils/extract-file-info-or-throw.utils.ts
index 2f93f9530f..5c5baf56ad 100644
--- a/packages/twenty-server/src/engine/core-modules/file/utils/extract-file-info.utils.ts
+++ b/packages/twenty-server/src/engine/core-modules/file/utils/extract-file-info-or-throw.utils.ts
@@ -10,9 +10,14 @@ import {
 } from 'src/engine/core-modules/file-storage/interfaces/file-storage-exception';
 
 import { detectPdf } from '@file-type/pdf';
+import { TWENTY_MIME_POLICY } from 'src/engine/core-modules/file/constants/twenty-mime-policy.constant';
 import { buildFileInfo } from 'src/engine/core-modules/file/utils/build-file-info.utils';
 
-export const extractFileInfo = async ({
+const fileTypeParser = new FileTypeParser({
+  customDetectors: [detectPdf],
+});
+
+export const extractFileInfoOrThrow = async ({
   file,
   filename,
 }: {
@@ -21,12 +26,8 @@ export const extractFileInfo = async ({
 }) => {
   const { ext: declaredExt } = buildFileInfo(filename);
 
-  const fileParser = new FileTypeParser({
-    customDetectors: [detectPdf],
-  });
-
   const { ext: detectedExt, mime: detectedMime } =
-    (await fileParser.fromBuffer(file)) ?? {};
+    (await fileTypeParser.fromBuffer(file)) ?? {};
 
   if (isDefined(detectedExt) && isDefined(detectedMime)) {
     return {
@@ -40,6 +41,22 @@ export const extractFileInfo = async ({
   let mimeType: string = 'application/octet-stream';
 
   if (isNonEmptyString(ext)) {
+    // Twenty policy wins over the ext-based fallback for the (small) set of
+    // extensions where mrmime's IANA mapping collides with a developer-tooling
+    // convention. This branch is only reached when file-type's magic-byte
+    // sniff returned nothing — when the bytes actually match (e.g. a real
+    // MPEG-TS video at foo.ts), we already returned above.
+    //
+    // For .ts/.tsx the policy is also load-bearing for correctness: without
+    // it, lookup('ts') → 'video/mp2t' is in file-type's supportedMimeTypes,
+    // so the check below would throw INVALID_EXTENSION on every TypeScript
+    // source upload.
+    const policyMime = TWENTY_MIME_POLICY[ext];
+
+    if (isDefined(policyMime)) {
+      return { mimeType: policyMime, ext };
+    }
+
     const mimeTypeFromExtension = lookup(ext);
 
     if (
diff --git a/packages/twenty-server/src/engine/core-modules/logic-function/logic-function-resource/logic-function-resource.service.ts b/packages/twenty-server/src/engine/core-modules/logic-function/logic-function-resource/logic-function-resource.service.ts
index 31b03d6a82..47bd0e17a8 100644
--- a/packages/twenty-server/src/engine/core-modules/logic-function/logic-function-resource/logic-function-resource.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/logic-function/logic-function-resource/logic-function-resource.service.ts
@@ -94,7 +94,6 @@ export class LogicFunctionResourceService {
       fileFolder: FileFolder.Source,
       resourcePath: sourceHandlerPath,
       sourceFile: sourceFile.content,
-      mimeType: 'application/typescript',
       settings: {
         isTemporaryFile: false,
         toDelete: false,
@@ -107,7 +106,6 @@ export class LogicFunctionResourceService {
       fileFolder: FileFolder.BuiltLogicFunction,
       resourcePath: builtHandlerPath,
       sourceFile: builtFile.content,
-      mimeType: 'application/javascript',
       settings: {
         isTemporaryFile: false,
         toDelete: false,
@@ -139,7 +137,6 @@ export class LogicFunctionResourceService {
       resourcePath: sourceHandlerPath,
       sourceFile: sourceHandlerCode,
       settings: { isTemporaryFile: false, toDelete: false },
-      mimeType: 'application/typescript',
       queryRunner,
     });
   }
@@ -172,7 +169,6 @@ export class LogicFunctionResourceService {
       fileFolder: FileFolder.BuiltLogicFunction,
       resourcePath: builtHandlerPath,
       sourceFile: builtCode,
-      mimeType: 'application/javascript',
       settings: {
         isTemporaryFile: false,
         toDelete: false,
diff --git a/packages/twenty-server/src/engine/core-modules/sdk-client/sdk-client-generation.service.ts b/packages/twenty-server/src/engine/core-modules/sdk-client/sdk-client-generation.service.ts
index b2e80595c2..2a75b486e8 100644
--- a/packages/twenty-server/src/engine/core-modules/sdk-client/sdk-client-generation.service.ts
+++ b/packages/twenty-server/src/engine/core-modules/sdk-client/sdk-client-generation.service.ts
@@ -157,7 +157,6 @@ export class SdkClientGenerationService {
         fileFolder: FileFolder.GeneratedSdkClient,
         resourcePath: SDK_CLIENT_ARCHIVE_NAME,
         sourceFile: archiveBuffer,
-        mimeType: 'application/zip',
         settings: { isTemporaryFile: false, toDelete: false },
       });
 
diff --git a/packages/twenty-server/src/engine/core-modules/tool/tools/code-interpreter-tool/code-interpreter-tool.ts b/packages/twenty-server/src/engine/core-modules/tool/tools/code-interpreter-tool/code-interpreter-tool.ts
index 79241faa85..1ab91d5b84 100644
--- a/packages/twenty-server/src/engine/core-modules/tool/tools/code-interpreter-tool/code-interpreter-tool.ts
+++ b/packages/twenty-server/src/engine/core-modules/tool/tools/code-interpreter-tool/code-interpreter-tool.ts
@@ -337,7 +337,6 @@ export class CodeInterpreterTool implements Tool {
 
       const savedFile = await this.fileStorageService.writeFile({
         sourceFile: file.content,
-        mimeType: file.mimeType,
         fileFolder: FileFolder.AgentChat,
         applicationUniversalIdentifier:
           workspaceCustomFlatApplication.universalIdentifier,
diff --git a/packages/twenty-server/src/engine/workspace-manager/dev-seeder/data/services/dev-seeder-data.service.ts b/packages/twenty-server/src/engine/workspace-manager/dev-seeder/data/services/dev-seeder-data.service.ts
index 71ef809376..72c4ec298e 100644
--- a/packages/twenty-server/src/engine/workspace-manager/dev-seeder/data/services/dev-seeder-data.service.ts
+++ b/packages/twenty-server/src/engine/workspace-manager/dev-seeder/data/services/dev-seeder-data.service.ts
@@ -465,7 +465,6 @@ export class DevSeederDataService {
 
       await this.fileStorageService.writeFile({
         sourceFile,
-        mimeType: metadata.mimeType,
         fileFolder: FileFolder.FilesField,
         applicationUniversalIdentifier,
         workspaceId,
diff --git a/packages/twenty-server/src/engine/workspace-manager/standard-objects-prefill-data/services/prefill-front-component.service.ts b/packages/twenty-server/src/engine/workspace-manager/standard-objects-prefill-data/services/prefill-front-component.service.ts
index 5890faf8d3..c4f24d7910 100644
--- a/packages/twenty-server/src/engine/workspace-manager/standard-objects-prefill-data/services/prefill-front-component.service.ts
+++ b/packages/twenty-server/src/engine/workspace-manager/standard-objects-prefill-data/services/prefill-front-component.service.ts
@@ -83,7 +83,6 @@ export class PrefillFrontComponentService {
         fileFolder: FileFolder.Source,
         resourcePath: sourceComponentPath,
         sourceFile: sourceFile.content,
-        mimeType: 'application/typescript',
         settings: {
           isTemporaryFile: false,
           toDelete: false,
@@ -97,7 +96,6 @@ export class PrefillFrontComponentService {
         fileFolder: FileFolder.BuiltFrontComponent,
         resourcePath: builtComponentPath,
         sourceFile: builtFile.content,
-        mimeType: 'application/javascript',
         settings: {
           isTemporaryFile: false,
           toDelete: false,
diff --git a/packages/twenty-server/test/integration/metadata/suites/application/__snapshots__/failing-upload-application-file-mime-mismatch.integration-spec.ts.snap b/packages/twenty-server/test/integration/metadata/suites/application/__snapshots__/failing-upload-application-file-mime-mismatch.integration-spec.ts.snap
new file mode 100644
index 0000000000..53554c8e67
--- /dev/null
+++ b/packages/twenty-server/test/integration/metadata/suites/application/__snapshots__/failing-upload-application-file-mime-mismatch.integration-spec.ts.snap
@@ -0,0 +1,37 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Upload application file should fail on mime/magic-byte mismatch when a PublicAsset .pdf path is uploaded with plain text body (magic-byte mismatch) 1`] = `
+{
+  "extensions": {
+    "code": "BAD_USER_INPUT",
+    "subCode": "INVALID_EXTENSION",
+    "userFriendlyMessage": "The file extension doesn't match the file content. Please check that your file is not corrupted and has the correct extension.",
+  },
+  "message": "File content does not match its extension. The file has extension 'pdf' (expected mime type: application/pdf), but the file content could not be detected as this type. The file may be corrupted, have the wrong extension, or be a security risk.",
+  "name": "UserInputError",
+}
+`;
+
+exports[`Upload application file should fail on mime/magic-byte mismatch when a PublicAsset .png path is uploaded with plain text body (magic-byte mismatch) 1`] = `
+{
+  "extensions": {
+    "code": "BAD_USER_INPUT",
+    "subCode": "INVALID_EXTENSION",
+    "userFriendlyMessage": "The file extension doesn't match the file content. Please check that your file is not corrupted and has the correct extension.",
+  },
+  "message": "File content does not match its extension. The file has extension 'png' (expected mime type: image/png), but the file content could not be detected as this type. The file may be corrupted, have the wrong extension, or be a security risk.",
+  "name": "UserInputError",
+}
+`;
+
+exports[`Upload application file should fail on mime/magic-byte mismatch when a PublicAsset .zip path is uploaded with plain text body (magic-byte mismatch) 1`] = `
+{
+  "extensions": {
+    "code": "BAD_USER_INPUT",
+    "subCode": "INVALID_EXTENSION",
+    "userFriendlyMessage": "The file extension doesn't match the file content. Please check that your file is not corrupted and has the correct extension.",
+  },
+  "message": "File content does not match its extension. The file has extension 'zip' (expected mime type: application/zip), but the file content could not be detected as this type. The file may be corrupted, have the wrong extension, or be a security risk.",
+  "name": "UserInputError",
+}
+`;
diff --git a/packages/twenty-server/test/integration/metadata/suites/application/failing-public-assets-controller-download.integration-spec.ts b/packages/twenty-server/test/integration/metadata/suites/application/failing-public-assets-controller-download.integration-spec.ts
index 89f5bf389b..e4b2c3dc60 100644
--- a/packages/twenty-server/test/integration/metadata/suites/application/failing-public-assets-controller-download.integration-spec.ts
+++ b/packages/twenty-server/test/integration/metadata/suites/application/failing-public-assets-controller-download.integration-spec.ts
@@ -16,6 +16,7 @@ const UNKNOWN_APPLICATION_ID = uuidv4();
 
 const PUBLIC_ASSET_PATH = 'assets/logo.svg';
 const PUBLIC_ASSET_CONTENT = '<svg><circle r="10" /></svg>';
+const PERSISTED_PUBLIC_ASSET_CONTENT = '<svg><circle r="10"></circle></svg>';
 const PUBLIC_ASSET_CONTENT_TYPE = 'image/svg+xml';
 
 type FailingCase = {
@@ -81,8 +82,7 @@ describe('Public assets controller download should fail', () => {
     await setupApplicationForSync({
       applicationUniversalIdentifier: TEST_APP_UID,
       name: 'Test Public Assets Download Failure App',
-      description:
-        'App for testing failing public-assets controller downloads',
+      description: 'App for testing failing public-assets controller downloads',
       sourcePath: 'test-public-assets-download-failure',
     });
 
@@ -93,9 +93,6 @@ describe('Public assets controller download should fail', () => {
 
     applicationId = id;
 
-    // A real public asset must exist so the "no content leak" guard below is
-    // meaningful — without it, `not.toContain(PUBLIC_ASSET_CONTENT)` would
-    // pass trivially regardless of the controller's behavior.
     jest.useRealTimers();
 
     await uploadApplicationFile({
@@ -129,7 +126,7 @@ describe('Public assets controller download should fail', () => {
       jest.useFakeTimers();
 
       // The legitimate asset content must never leak through a failure path.
-      expect(response.text).not.toContain(PUBLIC_ASSET_CONTENT);
+      expect(response.text).not.toContain(PERSISTED_PUBLIC_ASSET_CONTENT);
 
       expectOneNotInternalServerErrorHttpResponseSnapshot({
         status: response.status,
diff --git a/packages/twenty-server/test/integration/metadata/suites/application/failing-upload-application-file-mime-mismatch.integration-spec.ts b/packages/twenty-server/test/integration/metadata/suites/application/failing-upload-application-file-mime-mismatch.integration-spec.ts
new file mode 100644
index 0000000000..b622a64b00
--- /dev/null
+++ b/packages/twenty-server/test/integration/metadata/suites/application/failing-upload-application-file-mime-mismatch.integration-spec.ts
@@ -0,0 +1,136 @@
+import { expectOneNotInternalServerErrorSnapshot } from 'test/integration/graphql/utils/expect-one-not-internal-server-error-snapshot.util';
+import { cleanupApplicationAndAppRegistration } from 'test/integration/metadata/suites/application/utils/cleanup-application-and-app-registration.util';
+import { setupApplicationForSync } from 'test/integration/metadata/suites/application/utils/setup-application-for-sync.util';
+import { uploadApplicationFile } from 'test/integration/metadata/suites/application/utils/upload-application-file.util';
+import {
+  type EachTestingContext,
+  eachTestingContextFilter,
+} from 'twenty-shared/testing';
+import { v4 as uuidv4 } from 'uuid';
+
+const TEST_APP_ID = uuidv4();
+
+const PNG_BUFFER = Buffer.from([
+  0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00, 0x0d, 0x49,
+  0x48, 0x44, 0x52,
+]);
+const TEXT_BUFFER = Buffer.from('not actually binary content', 'utf-8');
+
+type TestContext = {
+  applicationUniversalIdentifier: string;
+  fileFolder: string;
+  filePath: string;
+  fileBuffer: Buffer;
+  filename: string;
+  contentType: string;
+};
+
+const FAILING_TEST_CASES: EachTestingContext<TestContext>[] = [
+  {
+    title:
+      'when a PublicAsset .png path is uploaded with plain text body (magic-byte mismatch)',
+    context: {
+      applicationUniversalIdentifier: TEST_APP_ID,
+      fileFolder: 'PublicAsset',
+      filePath: 'assets/fake-image.png',
+      fileBuffer: TEXT_BUFFER,
+      filename: 'fake-image.png',
+      contentType: 'image/png',
+    },
+  },
+  {
+    title:
+      'when a PublicAsset .pdf path is uploaded with plain text body (magic-byte mismatch)',
+    context: {
+      applicationUniversalIdentifier: TEST_APP_ID,
+      fileFolder: 'PublicAsset',
+      filePath: 'docs/fake.pdf',
+      fileBuffer: TEXT_BUFFER,
+      filename: 'fake.pdf',
+      contentType: 'application/pdf',
+    },
+  },
+  {
+    title:
+      'when a PublicAsset .zip path is uploaded with plain text body (magic-byte mismatch)',
+    context: {
+      applicationUniversalIdentifier: TEST_APP_ID,
+      fileFolder: 'PublicAsset',
+      filePath: 'archives/fake.zip',
+      fileBuffer: TEXT_BUFFER,
+      filename: 'fake.zip',
+      contentType: 'application/zip',
+    },
+  },
+];
+
+describe('Upload application file should fail on mime/magic-byte mismatch', () => {
+  beforeAll(async () => {
+    await setupApplicationForSync({
+      applicationUniversalIdentifier: TEST_APP_ID,
+      name: 'Test Upload Mime Mismatch App',
+      description: 'App for testing magic-byte vs extension validation',
+      sourcePath: 'test-upload-mime-mismatch',
+    });
+  }, 60000);
+
+  afterAll(async () => {
+    await cleanupApplicationAndAppRegistration({
+      applicationUniversalIdentifier: TEST_APP_ID,
+    });
+  });
+
+  it.each(eachTestingContextFilter(FAILING_TEST_CASES))(
+    '$title',
+    async ({ context }) => {
+      jest.useRealTimers();
+
+      const { errors } = await uploadApplicationFile({
+        applicationUniversalIdentifier: context.applicationUniversalIdentifier,
+        fileFolder: context.fileFolder,
+        filePath: context.filePath,
+        fileBuffer: context.fileBuffer,
+        filename: context.filename,
+        contentType: context.contentType,
+        expectToFail: true,
+      });
+
+      jest.useFakeTimers();
+
+      expectOneNotInternalServerErrorSnapshot({ errors });
+    },
+    60000,
+  );
+
+  it('should succeed but persist server-derived mime when uploader-controlled mime is misleading', async () => {
+    jest.useRealTimers();
+
+    const filePath = 'assets/legit-image.png';
+
+    const { data, errors } = await uploadApplicationFile({
+      applicationUniversalIdentifier: TEST_APP_ID,
+      fileFolder: 'PublicAsset',
+      filePath,
+      fileBuffer: PNG_BUFFER,
+      filename: 'legit-image.png',
+      // Misleading multipart mime — server should ignore it and persist image/png.
+      contentType: 'text/html',
+      expectToFail: false,
+    });
+
+    jest.useFakeTimers();
+
+    expect(errors).toBeUndefined();
+    expect(data.uploadApplicationFile).toEqual({
+      id: expect.any(String),
+      path: `public-asset/${filePath}`,
+    });
+
+    const [row] = await globalThis.testDataSource.query(
+      `SELECT "mimeType" FROM core."file" WHERE id = $1`,
+      [data.uploadApplicationFile.id],
+    );
+
+    expect(row.mimeType).toBe('image/png');
+  }, 60000);
+});
diff --git a/packages/twenty-server/test/integration/metadata/suites/application/successful-public-assets-controller-download.integration-spec.ts b/packages/twenty-server/test/integration/metadata/suites/application/successful-public-assets-controller-download.integration-spec.ts
index 53a56e8826..6e4b621a81 100644
--- a/packages/twenty-server/test/integration/metadata/suites/application/successful-public-assets-controller-download.integration-spec.ts
+++ b/packages/twenty-server/test/integration/metadata/suites/application/successful-public-assets-controller-download.integration-spec.ts
@@ -9,6 +9,8 @@ const TEST_WORKSPACE_ID = '20202020-1c25-4d02-bf25-6aeccf7ea419';
 
 const PUBLIC_ASSET_PATH = 'assets/logo.svg';
 const PUBLIC_ASSET_CONTENT = '<svg><circle r="10" /></svg>';
+const EXPECTED_SANITIZED_PUBLIC_ASSET_CONTENT =
+  '<svg><circle r="10"></circle></svg>';
 const PUBLIC_ASSET_CONTENT_TYPE = 'image/svg+xml';
 
 describe('Public assets controller download should succeed', () => {
@@ -76,7 +78,7 @@ describe('Public assets controller download should succeed', () => {
     );
     expect(response.headers['x-content-type-options']).toBe('nosniff');
     expect((response.body as Buffer).toString('utf-8')).toBe(
-      PUBLIC_ASSET_CONTENT,
+      EXPECTED_SANITIZED_PUBLIC_ASSET_CONTENT,
     );
   }, 30000);
 });
diff --git a/packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file-svg-sanitization.integration-spec.ts b/packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file-svg-sanitization.integration-spec.ts
new file mode 100644
index 0000000000..5ca4449cc4
--- /dev/null
+++ b/packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file-svg-sanitization.integration-spec.ts
@@ -0,0 +1,126 @@
+import { readFileSync } from 'fs';
+import { join } from 'path';
+
+import { cleanupApplicationAndAppRegistration } from 'test/integration/metadata/suites/application/utils/cleanup-application-and-app-registration.util';
+import { setupApplicationForSync } from 'test/integration/metadata/suites/application/utils/setup-application-for-sync.util';
+import { uploadApplicationFile } from 'test/integration/metadata/suites/application/utils/upload-application-file.util';
+import { v4 as uuidv4 } from 'uuid';
+
+const TEST_APP_ID = uuidv4();
+const TEST_WORKSPACE_ID = '20202020-1c25-4d02-bf25-6aeccf7ea419';
+const STORAGE_LOCAL_PATH = join(process.cwd(), '.local-storage');
+
+const MALICIOUS_SVG = `<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" onload="alert(1)">
+  <script>alert('xss')</script>
+  <a xlink:href="javascript:alert('xss-link')">
+    <circle cx="50" cy="50" r="40" />
+  </a>
+</svg>`;
+
+// Deterministic DOMPurify output for MALICIOUS_SVG. Shape:
+//   - <script>...</script> stripped (the two leading spaces on that line are
+//     preserved — DOMPurify removes the element, not surrounding whitespace).
+//   - onload="..." attribute stripped from <svg>.
+//   - xlink:href="javascript:..." stripped from <a> (anchor element kept).
+//   - <circle .../> self-closing form normalized to <circle ...></circle>.
+// Encoded as a single-line literal so whitespace is unambiguous.
+const EXPECTED_SANITIZED_MALICIOUS_SVG =
+  '<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">\n  \n  <a>\n    <circle cx="50" cy="50" r="40"></circle>\n  </a>\n</svg>';
+
+const BENIGN_SVG =
+  '<svg xmlns="http://www.w3.org/2000/svg" width="50" height="50"><rect width="50" height="50" fill="red" /></svg>';
+
+const EXPECTED_SANITIZED_BENIGN_SVG =
+  '<svg xmlns="http://www.w3.org/2000/svg" width="50" height="50"><rect width="50" height="50" fill="red"></rect></svg>';
+
+describe('Upload application file — SVG sanitization (end-to-end)', () => {
+  beforeAll(async () => {
+    await setupApplicationForSync({
+      applicationUniversalIdentifier: TEST_APP_ID,
+      name: 'Test SVG Sanitization App',
+      description: 'App for verifying SVG sanitization end-to-end',
+      sourcePath: 'test-svg-sanitization',
+    });
+  }, 60000);
+
+  afterAll(async () => {
+    await cleanupApplicationAndAppRegistration({
+      applicationUniversalIdentifier: TEST_APP_ID,
+    });
+  });
+
+  it('strips scripts, event handlers, and javascript: URIs from an uploaded SVG, persisting the exact sanitized content with image/svg+xml mime', async () => {
+    jest.useRealTimers();
+
+    const filePath = 'assets/malicious.svg';
+
+    const { data, errors } = await uploadApplicationFile({
+      applicationUniversalIdentifier: TEST_APP_ID,
+      fileFolder: 'PublicAsset',
+      filePath,
+      fileBuffer: Buffer.from(MALICIOUS_SVG, 'utf-8'),
+      filename: 'malicious.svg',
+      contentType: 'image/svg+xml',
+      expectToFail: false,
+    });
+
+    jest.useFakeTimers();
+
+    expect(errors).toBeUndefined();
+    expect(data.uploadApplicationFile).toEqual({
+      id: expect.any(String),
+      path: `public-asset/${filePath}`,
+    });
+
+    const [row] = await globalThis.testDataSource.query(
+      `SELECT "mimeType" FROM core."file" WHERE id = $1`,
+      [data.uploadApplicationFile.id],
+    );
+
+    expect(row.mimeType).toBe('image/svg+xml');
+
+    const onDiskPath = join(
+      STORAGE_LOCAL_PATH,
+      TEST_WORKSPACE_ID,
+      TEST_APP_ID,
+      'public-asset',
+      filePath,
+    );
+
+    const storedContent = readFileSync(onDiskPath, 'utf-8');
+
+    expect(storedContent).toBe(EXPECTED_SANITIZED_MALICIOUS_SVG);
+  }, 60000);
+
+  it('preserves a benign SVG with only DOMPurify structural normalization', async () => {
+    jest.useRealTimers();
+
+    const filePath = 'assets/benign.svg';
+
+    const { errors } = await uploadApplicationFile({
+      applicationUniversalIdentifier: TEST_APP_ID,
+      fileFolder: 'PublicAsset',
+      filePath,
+      fileBuffer: Buffer.from(BENIGN_SVG, 'utf-8'),
+      filename: 'benign.svg',
+      contentType: 'image/svg+xml',
+      expectToFail: false,
+    });
+
+    jest.useFakeTimers();
+
+    expect(errors).toBeUndefined();
+
+    const onDiskPath = join(
+      STORAGE_LOCAL_PATH,
+      TEST_WORKSPACE_ID,
+      TEST_APP_ID,
+      'public-asset',
+      filePath,
+    );
+
+    const storedContent = readFileSync(onDiskPath, 'utf-8');
+
+    expect(storedContent).toBe(EXPECTED_SANITIZED_BENIGN_SVG);
+  }, 60000);
+});
diff --git a/packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file.integration-spec.ts b/packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file.integration-spec.ts
index 0bf650239c..a550242fd5 100644
--- a/packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file.integration-spec.ts
+++ b/packages/twenty-server/test/integration/metadata/suites/application/successful-upload-application-file.integration-spec.ts
@@ -10,80 +10,119 @@ import { v4 as uuidv4 } from 'uuid';
 
 const TEST_APP_ID = uuidv4();
 
-type TestContext = {
+type UploadInput = {
   fileFolder: string;
-  fileFolderValue: FileFolder;
   filePath: string;
   filename: string;
   contentType: string;
   fileContent: string;
 };
 
+type UploadExpected = {
+  fileFolderValue: FileFolder;
+  persistedMimeType: string;
+};
+
+type TestContext = {
+  input: UploadInput;
+  expected: UploadExpected;
+};
+
 const SUCCESSFUL_TEST_CASES: EachTestingContext<TestContext>[] = [
   {
     title: 'when uploading a built front component',
     context: {
-      fileFolder: 'BuiltFrontComponent',
-      fileFolderValue: FileFolder.BuiltFrontComponent,
-      filePath: 'src/components/my-component.mjs',
-      filename: 'my-component.mjs',
-      contentType: 'application/javascript',
-      fileContent: 'export default function MyComponent() {}',
+      input: {
+        fileFolder: 'BuiltFrontComponent',
+        filePath: 'src/components/my-component.mjs',
+        filename: 'my-component.mjs',
+        contentType: 'application/javascript',
+        fileContent: 'export default function MyComponent() {}',
+      },
+      expected: {
+        fileFolderValue: FileFolder.BuiltFrontComponent,
+        persistedMimeType: 'text/javascript',
+      },
     },
   },
   {
     title: 'when uploading a built logic function',
     context: {
-      fileFolder: 'BuiltLogicFunction',
-      fileFolderValue: FileFolder.BuiltLogicFunction,
-      filePath: 'src/handlers/my-handler.mjs',
-      filename: 'my-handler.mjs',
-      contentType: 'application/javascript',
-      fileContent: 'export default async function handler() {}',
+      input: {
+        fileFolder: 'BuiltLogicFunction',
+        filePath: 'src/handlers/my-handler.mjs',
+        filename: 'my-handler.mjs',
+        contentType: 'application/javascript',
+        fileContent: 'export default async function handler() {}',
+      },
+      expected: {
+        fileFolderValue: FileFolder.BuiltLogicFunction,
+        persistedMimeType: 'text/javascript',
+      },
     },
   },
   {
     title: 'when uploading a source file',
     context: {
-      fileFolder: 'Source',
-      fileFolderValue: FileFolder.Source,
-      filePath: 'src/index.tsx',
-      filename: 'index.tsx',
-      contentType: 'text/plain',
-      fileContent: 'export const App = () => <div>Hello</div>;',
+      input: {
+        fileFolder: 'Source',
+        filePath: 'src/index.tsx',
+        filename: 'index.tsx',
+        contentType: 'text/plain',
+        fileContent: 'export const App = () => <div>Hello</div>;',
+      },
+      expected: {
+        fileFolderValue: FileFolder.Source,
+        persistedMimeType: 'application/typescript',
+      },
     },
   },
   {
     title: 'when uploading a public asset',
     context: {
-      fileFolder: 'PublicAsset',
-      fileFolderValue: FileFolder.PublicAsset,
-      filePath: 'assets/logo.svg',
-      filename: 'logo.svg',
-      contentType: 'image/svg+xml',
-      fileContent: '<svg></svg>',
+      input: {
+        fileFolder: 'PublicAsset',
+        filePath: 'assets/logo.svg',
+        filename: 'logo.svg',
+        contentType: 'image/svg+xml',
+        fileContent: '<svg></svg>',
+      },
+      expected: {
+        fileFolderValue: FileFolder.PublicAsset,
+        persistedMimeType: 'image/svg+xml',
+      },
     },
   },
   {
     title: 'when uploading a dependencies file',
     context: {
-      fileFolder: 'Dependencies',
-      fileFolderValue: FileFolder.Dependencies,
-      filePath: 'yarn.lock',
-      filename: 'yarn.lock',
-      contentType: 'text/plain',
-      fileContent: '# yarn lockfile v1',
+      input: {
+        fileFolder: 'Dependencies',
+        filePath: 'yarn.lock',
+        filename: 'yarn.lock',
+        contentType: 'text/plain',
+        fileContent: '# yarn lockfile v1',
+      },
+      expected: {
+        fileFolderValue: FileFolder.Dependencies,
+        persistedMimeType: 'application/octet-stream',
+      },
     },
   },
   {
     title: 'when uploading a file in a nested directory path',
     context: {
-      fileFolder: 'Source',
-      fileFolderValue: FileFolder.Source,
-      filePath: 'src/modules/auth/login/login.component.tsx',
-      filename: 'login.component.tsx',
-      contentType: 'text/plain',
-      fileContent: 'export const Login = () => null;',
+      input: {
+        fileFolder: 'Source',
+        filePath: 'src/modules/auth/login/login.component.tsx',
+        filename: 'login.component.tsx',
+        contentType: 'text/plain',
+        fileContent: 'export const Login = () => null;',
+      },
+      expected: {
+        fileFolderValue: FileFolder.Source,
+        persistedMimeType: 'application/typescript',
+      },
     },
   },
 ];
@@ -106,16 +145,16 @@ describe('Upload application file should succeed', () => {
 
   it.each(eachTestingContextFilter(SUCCESSFUL_TEST_CASES))(
     '$title',
-    async ({ context }) => {
+    async ({ context: { input, expected } }) => {
       jest.useRealTimers();
 
       const { data, errors } = await uploadApplicationFile({
         applicationUniversalIdentifier: TEST_APP_ID,
-        fileFolder: context.fileFolder,
-        filePath: context.filePath,
-        fileBuffer: Buffer.from(context.fileContent),
-        filename: context.filename,
-        contentType: context.contentType,
+        fileFolder: input.fileFolder,
+        filePath: input.filePath,
+        fileBuffer: Buffer.from(input.fileContent),
+        filename: input.filename,
+        contentType: input.contentType,
         expectToFail: false,
       });
 
@@ -124,8 +163,15 @@ describe('Upload application file should succeed', () => {
       expect(errors).toBeUndefined();
       expect(data.uploadApplicationFile).toEqual({
         id: expect.any(String),
-        path: `${context.fileFolderValue}/${context.filePath}`,
+        path: `${expected.fileFolderValue}/${input.filePath}`,
       });
+
+      const [row] = await globalThis.testDataSource.query(
+        `SELECT "mimeType" FROM core."file" WHERE id = $1`,
+        [data.uploadApplicationFile.id],
+      );
+
+      expect(row.mimeType).toBe(expected.persistedMimeType);
     },
     60000,
   );