diff --git a/apps/admin/src/api/imports.ts b/apps/admin/src/api/imports.ts
index d87800a..635e8c2 100644
--- a/apps/admin/src/api/imports.ts
+++ b/apps/admin/src/api/imports.ts
@@ -31,9 +31,7 @@ export async function createImportRun(
   if (options.mapping && Object.keys(options.mapping).length > 0) {
     form.append('mapping', JSON.stringify(options.mapping));
   }
-  const res = await api.post<ApiEnvelope<ImportRunDetail>>('/imports/runs', form, {
-    headers: { 'Content-Type': 'multipart/form-data' },
-  });
+  const res = await api.post<ApiEnvelope<ImportRunDetail>>('/imports/runs', form);
   return res.data;
 }
 
diff --git a/apps/admin/src/components/AiChat/api.ts b/apps/admin/src/components/AiChat/api.ts
index f336abc..bcbd8c3 100644
--- a/apps/admin/src/components/AiChat/api.ts
+++ b/apps/admin/src/components/AiChat/api.ts
@@ -35,7 +35,6 @@ export const aiChatApi = {
     form.append('file', file);
     return (
       await api.post<AiApiResponse<AiAttachment>>('/ai/chat/attachments', form, {
-        headers: { 'Content-Type': 'multipart/form-data' },
         timeout: 120_000,
       })
     ).data;
diff --git a/apps/admin/src/components/StudentProfileContent/AttachmentsTab.tsx b/apps/admin/src/components/StudentProfileContent/AttachmentsTab.tsx
index 1a0f132..c987f78 100644
--- a/apps/admin/src/components/StudentProfileContent/AttachmentsTab.tsx
+++ b/apps/admin/src/components/StudentProfileContent/AttachmentsTab.tsx
@@ -29,9 +29,7 @@ export const AttachmentsTab: React.FC<TabProps & { data: AttachmentRecord[] }> =
   );
   const uploadAttachmentMutation = useApiMutation(
     async (formData: FormData) =>
-      api.post(`/archive/${studentId}/attachments`, formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post(`/archive/${studentId}/attachments`, formData),
     { invalidate: [['archive', studentId]] },
   );
 
diff --git a/apps/admin/src/pages/ClassroomRentals/index.tsx b/apps/admin/src/pages/ClassroomRentals/index.tsx
index d2d5bc4..bc7bc4b 100644
--- a/apps/admin/src/pages/ClassroomRentals/index.tsx
+++ b/apps/admin/src/pages/ClassroomRentals/index.tsx
@@ -140,9 +140,7 @@ const ClassroomRentalsPage: React.FC = () => {
   );
   const uploadContractMutation = useApiMutation(
     async ({ id, formData }: { id: number; formData: FormData }) =>
-      api.post(`/classroom-rentals/${id}/contract`, formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post(`/classroom-rentals/${id}/contract`, formData),
     { invalidate: [['classroom-rentals']] },
   );
 
diff --git a/apps/admin/src/pages/Classrooms/index.tsx b/apps/admin/src/pages/Classrooms/index.tsx
index 869b901..5526afb 100644
--- a/apps/admin/src/pages/Classrooms/index.tsx
+++ b/apps/admin/src/pages/Classrooms/index.tsx
@@ -110,9 +110,7 @@ const ClassroomsPage: React.FC = () => {
   );
   const importMutation = useApiMutation(
     async (formData: FormData) =>
-      api.post('/classrooms/import', formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post('/classrooms/import', formData),
     { invalidate: [['classrooms']] },
   );
 
diff --git a/apps/admin/src/pages/Expenses/index.tsx b/apps/admin/src/pages/Expenses/index.tsx
index f1e7763..e8d9dff 100644
--- a/apps/admin/src/pages/Expenses/index.tsx
+++ b/apps/admin/src/pages/Expenses/index.tsx
@@ -137,16 +137,12 @@ const ExpensesPage: React.FC = () => {
     ),
     importUtility: useApiMutation(
       async (formData: FormData) =>
-        api.post('/expenses/utility/import', formData, {
-          headers: { 'Content-Type': 'multipart/form-data' },
-        }),
+        api.post('/expenses/utility/import', formData),
       { invalidate: [['expenses']] },
     ),
     importPersonal: useApiMutation(
       async (formData: FormData) =>
-        api.post('/expenses/personal/import', formData, {
-          headers: { 'Content-Type': 'multipart/form-data' },
-        }),
+        api.post('/expenses/personal/import', formData),
       { invalidate: [['expenses']] },
     ),
     archiveRoom: useApiMutation(
diff --git a/apps/admin/src/pages/Occupancies/useOccupancyMutations.ts b/apps/admin/src/pages/Occupancies/useOccupancyMutations.ts
index 7e90a16..8c26a0d 100644
--- a/apps/admin/src/pages/Occupancies/useOccupancyMutations.ts
+++ b/apps/admin/src/pages/Occupancies/useOccupancyMutations.ts
@@ -44,9 +44,7 @@ export function useOccupancyMutations() {
   );
   const importMutation = useApiMutation(
     async ({ formData, params }: { formData: FormData; params: string }) =>
-      api.post(`/occupancies/import?${params}`, formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post(`/occupancies/import?${params}`, formData),
     { invalidate: invalidateOccupancies },
   );
 
diff --git a/apps/admin/src/pages/Rooms/useRoomMutations.ts b/apps/admin/src/pages/Rooms/useRoomMutations.ts
index 17ec1ac..9195594 100644
--- a/apps/admin/src/pages/Rooms/useRoomMutations.ts
+++ b/apps/admin/src/pages/Rooms/useRoomMutations.ts
@@ -143,9 +143,7 @@ export function useRoomMutations(editing: any) {
   );
   const importMutation = useApiMutation(
     async (formData: FormData) =>
-      api.post<{ message?: string }>('/rooms/import', formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post<{ message?: string }>('/rooms/import', formData),
     { invalidate: [['rooms']] },
   );
 
diff --git a/apps/admin/src/pages/Students/index.tsx b/apps/admin/src/pages/Students/index.tsx
index 1ccdebf..c601801 100644
--- a/apps/admin/src/pages/Students/index.tsx
+++ b/apps/admin/src/pages/Students/index.tsx
@@ -228,16 +228,12 @@ const StudentsPage: React.FC = () => {
   );
   const importMutation = useApiMutation(
     async (formData: FormData) =>
-      api.post('/students/import', formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post('/students/import', formData),
     { invalidate: invalidateStudents },
   );
   const importMatchMutation = useApiMutation(
     async (formData: FormData) =>
-      api.post('/students/import-match', formData, {
-        headers: { 'Content-Type': 'multipart/form-data' },
-      }),
+      api.post('/students/import-match', formData),
     { invalidate: invalidateStudents },
   );
 
diff --git a/apps/server/src/ai-chat/ai-excel-reader.service.ts b/apps/server/src/ai-chat/ai-excel-reader.service.ts
index 67ef99d..83d1d98 100644
--- a/apps/server/src/ai-chat/ai-excel-reader.service.ts
+++ b/apps/server/src/ai-chat/ai-excel-reader.service.ts
@@ -86,7 +86,7 @@ export class AiExcelReaderService {
 
   private async loadWithExcelJs(buffer: Buffer): Promise<ExcelSheetRows[]> {
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(buffer as unknown as ArrayBuffer);
     const sheets: ExcelSheetRows[] = [];
     workbook.eachSheet((sheet) => {
       const rows: string[][] = [];
diff --git a/apps/server/src/classrooms/classrooms.controller.ts b/apps/server/src/classrooms/classrooms.controller.ts
index 92b9662..1cd7e6d 100644
--- a/apps/server/src/classrooms/classrooms.controller.ts
+++ b/apps/server/src/classrooms/classrooms.controller.ts
@@ -158,7 +158,7 @@ export class ClassroomsController {
   async importExcel(@UploadedFile() file: Express.Multer.File, @Request() req: any) {
     const { ipAddress, userAgent } = extractRequestInfo(req);
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(file.buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(file.buffer as unknown as ArrayBuffer);
     const ws = workbook.worksheets[0];
     const rows: any[] = [];
     ws.eachRow((row, idx) => {
diff --git a/apps/server/src/expenses/expenses.controller.ts b/apps/server/src/expenses/expenses.controller.ts
index 011a93b..76aa6ad 100644
--- a/apps/server/src/expenses/expenses.controller.ts
+++ b/apps/server/src/expenses/expenses.controller.ts
@@ -316,7 +316,7 @@ export class ExpensesController {
   @UseInterceptors(FileInterceptor('file'))
   async importUtilityExpenses(@UploadedFile() file: Express.Multer.File, @Request() req: any) {
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(file.buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(file.buffer as unknown as ArrayBuffer);
     const ws = workbook.worksheets[0];
     const rows: any[] = [];
     ws.eachRow((row, idx) => {
@@ -381,7 +381,7 @@ export class ExpensesController {
   @UseInterceptors(FileInterceptor('file'))
   async importPersonalExpenses(@UploadedFile() file: Express.Multer.File, @Request() req: any) {
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(file.buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(file.buffer as unknown as ArrayBuffer);
     const ws = workbook.worksheets[0];
     const rows: any[] = [];
     ws.eachRow((row, idx) => {
diff --git a/apps/server/src/imports/imports.workbook.ts b/apps/server/src/imports/imports.workbook.ts
index dcfeaa5..e4f248e 100644
--- a/apps/server/src/imports/imports.workbook.ts
+++ b/apps/server/src/imports/imports.workbook.ts
@@ -84,7 +84,7 @@ export async function parseSheets(
     if (kind === 'csv') {
       await workbook.csv.read(Readable.from(Buffer.from(buffer)));
     } else {
-      await workbook.xlsx.load(buffer.buffer as ArrayBuffer);
+      await workbook.xlsx.load(buffer as unknown as ArrayBuffer);
     }
     const sheets = extractSheets(workbook, headerRow);
     if (sheets.length === 0) {
diff --git a/apps/server/src/occupancies/occupancies.controller.ts b/apps/server/src/occupancies/occupancies.controller.ts
index ee49fa3..9ee2277 100644
--- a/apps/server/src/occupancies/occupancies.controller.ts
+++ b/apps/server/src/occupancies/occupancies.controller.ts
@@ -264,7 +264,7 @@ export class OccupanciesController {
     const { ipAddress, userAgent } = extractRequestInfo(req);
     if (!file?.buffer) throw new BadRequestException('请上传入住名单 Excel 文件');
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(file.buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(file.buffer as unknown as ArrayBuffer);
     const ws = workbook.worksheets[0];
     const rows = parseOccupancyImportWorksheet(ws);
     const result = await this.service.batchImportCheckIn(rows, {
diff --git a/apps/server/src/rooms/rooms.controller.ts b/apps/server/src/rooms/rooms.controller.ts
index dda7648..a7db9a8 100644
--- a/apps/server/src/rooms/rooms.controller.ts
+++ b/apps/server/src/rooms/rooms.controller.ts
@@ -343,7 +343,7 @@ export class RoomsController {
   async importExcel(@UploadedFile() file: Express.Multer.File, @Request() req: any) {
     const { ipAddress, userAgent } = extractRequestInfo(req);
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(file.buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(file.buffer as unknown as ArrayBuffer);
     const ws = workbook.worksheets[0];
     const rows: {
       roomNumber: string;
diff --git a/apps/server/src/students/students.controller.ts b/apps/server/src/students/students.controller.ts
index 2e85695..0920f64 100644
--- a/apps/server/src/students/students.controller.ts
+++ b/apps/server/src/students/students.controller.ts
@@ -255,7 +255,7 @@ export class StudentsController {
   @UseInterceptors(FileInterceptor('file'))
   async importExcel(@UploadedFile() file: Express.Multer.File, @Request() req: any) {
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(file.buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(file.buffer as unknown as ArrayBuffer);
     const importData = parseStudentImportWorkbook(workbook);
     // Resolve organization names to IDs
     for (const row of importData.students) {
@@ -280,7 +280,7 @@ export class StudentsController {
   @UseInterceptors(FileInterceptor('file'))
   async matchImport(@UploadedFile() file: Express.Multer.File, @Request() req: any) {
     const workbook = new ExcelJS.Workbook();
-    await workbook.xlsx.load(file.buffer.buffer as ArrayBuffer);
+    await workbook.xlsx.load(file.buffer as unknown as ArrayBuffer);
     const importData = parseStudentImportWorkbook(workbook);
     // Resolve organization names to IDs
     for (const row of importData.students) {