diff --git a/backend/src/modules/drawing/drawing-master-data.controller.ts b/backend/src/modules/drawing/drawing-master-data.controller.ts
index b523afb..1869d19 100644
--- a/backend/src/modules/drawing/drawing-master-data.controller.ts
+++ b/backend/src/modules/drawing/drawing-master-data.controller.ts
@@ -9,6 +9,7 @@ import {
   Query,
   UseGuards,
   ParseIntPipe,
+  Logger,
 } from '@nestjs/common';
 import {
   ApiTags,
@@ -27,6 +28,8 @@ import { RequirePermission } from '../../common/decorators/require-permission.de
 @UseGuards(JwtAuthGuard, RbacGuard)
 @Controller('drawings/master-data')
 export class DrawingMasterDataController {
+  private readonly logger = new Logger(DrawingMasterDataController.name);
+
   constructor(private readonly masterDataService: DrawingMasterDataService) {}
 
   // =====================================================
@@ -38,9 +41,12 @@ export class DrawingMasterDataController {
   @ApiQuery({ name: 'projectId', required: true, type: Number })
   @RequirePermission('document.view')
   getVolumes(@Query('projectId', ParseIntPipe) projectId: number) {
+    this.logger.log(`Fetching Contract Volumes for Project ID: ${projectId}`);
     return this.masterDataService.findAllVolumes(projectId);
   }
 
+  // ... (Create/Update/Delete methods remain unchanged) ...
+
   @Post('contract/volumes')
   @ApiOperation({ summary: 'Create Volume' })
   @RequirePermission('master_data.drawing_category.manage')
@@ -89,9 +95,14 @@ export class DrawingMasterDataController {
   @ApiQuery({ name: 'projectId', required: true, type: Number })
   @RequirePermission('document.view')
   getCategories(@Query('projectId', ParseIntPipe) projectId: number) {
+    this.logger.log(
+      `Fetching Contract Categories for Project ID: ${projectId}`
+    );
     return this.masterDataService.findAllCategories(projectId);
   }
 
+  // ... (Create/Update/Delete methods remain unchanged) ...
+
   @Post('contract/categories')
   @ApiOperation({ summary: 'Create Category' })
   @RequirePermission('master_data.drawing_category.manage')
@@ -140,9 +151,14 @@ export class DrawingMasterDataController {
   @ApiQuery({ name: 'projectId', required: true, type: Number })
   @RequirePermission('document.view')
   getContractSubCats(@Query('projectId', ParseIntPipe) projectId: number) {
+    this.logger.log(
+      `Fetching Contract Sub-Categories for Project ID: ${projectId}`
+    );
     return this.masterDataService.findAllContractSubCats(projectId);
   }
 
+  // ... (Create/Update/Delete methods remain unchanged) ...
+
   @Post('contract/sub-categories')
   @ApiOperation({ summary: 'Create Contract Sub-Category' })
   @RequirePermission('master_data.drawing_category.manage')
@@ -228,9 +244,14 @@ export class DrawingMasterDataController {
   @ApiQuery({ name: 'projectId', required: true, type: Number })
   @RequirePermission('document.view')
   getShopMainCats(@Query('projectId', ParseIntPipe) projectId: number) {
+    this.logger.log(
+      `Fetching Shop Main Categories for Project ID: ${projectId}`
+    );
     return this.masterDataService.findAllShopMainCats(projectId);
   }
 
+  // ... (Create/Update/Delete methods remain unchanged) ...
+
   @Post('shop/main-categories')
   @ApiOperation({ summary: 'Create Shop Main Category' })
   @RequirePermission('master_data.drawing_category.manage')
@@ -285,6 +306,9 @@ export class DrawingMasterDataController {
     @Query('projectId', ParseIntPipe) projectId: number,
     @Query('mainCategoryId') mainCategoryId?: number
   ) {
+    this.logger.log(
+      `Fetching Shop Sub-Categories for Project ID: ${projectId}, MainCategory: ${mainCategoryId}`
+    );
     return this.masterDataService.findAllShopSubCats(
       projectId,
       mainCategoryId ? Number(mainCategoryId) : undefined
diff --git a/frontend/app/(admin)/admin/doc-control/drawings/contract/categories/page.tsx b/frontend/app/(admin)/admin/doc-control/drawings/contract/categories/page.tsx
index deb83db..2334a54 100644
--- a/frontend/app/(admin)/admin/doc-control/drawings/contract/categories/page.tsx
+++ b/frontend/app/(admin)/admin/doc-control/drawings/contract/categories/page.tsx
@@ -232,10 +232,10 @@ function ManageMappings({ projectId }: { projectId: number }) {
                   <SelectValue placeholder="Select Sub-Category to add..." />
                 </SelectTrigger>
                 <SelectContent>
-                  {subCategories
+                  {(subCategories || [])
                     .filter(
                       (s: ContractSubCategory) =>
-                        !mappings.find((m: { subCategory: { id: number } }) => m.subCategory.id === s.id)
+                        !(mappings || []).find((m: { subCategory: { id: number } }) => m.subCategory?.id === s.id)
                     )
                     .map((s: ContractSubCategory) => (
                       <SelectItem key={s.id} value={String(s.id)}>
diff --git a/frontend/app/(admin)/admin/doc-control/drawings/shop/sub-categories/page.tsx b/frontend/app/(admin)/admin/doc-control/drawings/shop/sub-categories/page.tsx
index 9f4b1d6..95a0e02 100644
--- a/frontend/app/(admin)/admin/doc-control/drawings/shop/sub-categories/page.tsx
+++ b/frontend/app/(admin)/admin/doc-control/drawings/shop/sub-categories/page.tsx
@@ -1,19 +1,13 @@
-"use client";
+'use client';
 
-import { useState } from "react";
-import { GenericCrudTable } from "@/components/admin/reference/generic-crud-table";
-import { ColumnDef } from "@tanstack/react-table";
-import {
-  Select,
-  SelectContent,
-  SelectItem,
-  SelectTrigger,
-  SelectValue,
-} from "@/components/ui/select";
-import { Loader2, CheckCircle, XCircle } from "lucide-react";
-import { useProjects } from "@/hooks/use-master-data";
-import { drawingMasterDataService } from "@/lib/services/drawing-master-data.service";
-import { Badge } from "@/components/ui/badge";
+import { useState } from 'react';
+import { GenericCrudTable } from '@/components/admin/reference/generic-crud-table';
+import { ColumnDef } from '@tanstack/react-table';
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select';
+import { Loader2, CheckCircle, XCircle } from 'lucide-react';
+import { useProjects } from '@/hooks/use-master-data';
+import { drawingMasterDataService } from '@/lib/services/drawing-master-data.service';
+import { Badge } from '@/components/ui/badge';
 
 interface SubCategory {
   id: number;
@@ -28,46 +22,41 @@ export default function ShopSubCategoriesPage() {
   const [selectedProjectId, setSelectedProjectId] = useState<number | undefined>(undefined);
   const { data: projects = [], isLoading: isLoadingProjects } = useProjects();
 
+  console.log('Projects Data:', projects);
+
   const columns: ColumnDef<SubCategory>[] = [
     {
-      accessorKey: "subCategoryCode",
-      header: "Code",
+      accessorKey: 'subCategoryCode',
+      header: 'Code',
       cell: ({ row }) => (
         <Badge variant="outline" className="font-mono">
-          {row.getValue("subCategoryCode")}
+          {row.getValue('subCategoryCode')}
         </Badge>
       ),
     },
     {
-      accessorKey: "subCategoryName",
-      header: "Sub-category Name",
+      accessorKey: 'subCategoryName',
+      header: 'Sub-category Name',
     },
     {
-      accessorKey: "description",
-      header: "Description",
-      cell: ({ row }) => (
-        <span className="text-muted-foreground text-sm">
-          {row.getValue("description") || "-"}
-        </span>
-      ),
+      accessorKey: 'description',
+      header: 'Description',
+      cell: ({ row }) => <span className="text-muted-foreground text-sm">{row.getValue('description') || '-'}</span>,
     },
     {
-      accessorKey: "isActive",
-      header: "Active",
-      cell: ({ row }) => (
-        row.getValue("isActive") ? (
+      accessorKey: 'isActive',
+      header: 'Active',
+      cell: ({ row }) =>
+        row.getValue('isActive') ? (
           <CheckCircle className="h-4 w-4 text-green-600" />
         ) : (
           <XCircle className="h-4 w-4 text-red-600" />
-        )
-      ),
+        ),
     },
     {
-      accessorKey: "sortOrder",
-      header: "Order",
-      cell: ({ row }) => (
-        <span className="font-mono">{row.getValue("sortOrder")}</span>
-      ),
+      accessorKey: 'sortOrder',
+      header: 'Order',
+      cell: ({ row }) => <span className="font-mono">{row.getValue('sortOrder')}</span>,
     },
   ];
 
@@ -75,7 +64,7 @@ export default function ShopSubCategoriesPage() {
     <div className="flex items-center gap-4">
       <span className="text-sm font-medium">Project:</span>
       <Select
-        value={selectedProjectId?.toString() ?? ""}
+        value={selectedProjectId?.toString() ?? ''}
         onValueChange={(v) => setSelectedProjectId(v ? parseInt(v) : undefined)}
       >
         <SelectTrigger className="w-[300px]">
@@ -101,9 +90,7 @@ export default function ShopSubCategoriesPage() {
       <div className="p-6 space-y-6">
         <div>
           <h1 className="text-2xl font-bold">Shop Drawing Sub-categories</h1>
-          <p className="text-muted-foreground mt-1">
-            Manage sub-categories (หมวดหมู่ย่อย) for shop drawings
-          </p>
+          <p className="text-muted-foreground mt-1">Manage sub-categories (หมวดหมู่ย่อย) for shop drawings</p>
         </div>
         {projectFilter}
         <div className="text-center py-12 text-muted-foreground border rounded-lg border-dashed">
@@ -119,25 +106,29 @@ export default function ShopSubCategoriesPage() {
         entityName="Sub-category"
         title="Shop Drawing Sub-categories"
         description="Manage sub-categories (หมวดหมู่ย่อย) for shop drawings"
-        queryKey={["shop-drawing-sub-categories", String(selectedProjectId)]}
+        queryKey={['shop-drawing-sub-categories', String(selectedProjectId)]}
         fetchFn={() => drawingMasterDataService.getShopSubCategories(selectedProjectId)}
-        createFn={(data) => drawingMasterDataService.createShopSubCategory({
-          ...data,
-          projectId: selectedProjectId,
-          isActive: data.isActive === "true" || data.isActive === true
-        })}
-        updateFn={(id, data) => drawingMasterDataService.updateShopSubCategory(id, {
-          ...data,
-          isActive: data.isActive === "true" || data.isActive === true
-        })}
+        createFn={(data) =>
+          drawingMasterDataService.createShopSubCategory({
+            ...data,
+            projectId: selectedProjectId,
+            isActive: data.isActive === 'true' || data.isActive === true,
+          })
+        }
+        updateFn={(id, data) =>
+          drawingMasterDataService.updateShopSubCategory(id, {
+            ...data,
+            isActive: data.isActive === 'true' || data.isActive === true,
+          })
+        }
         deleteFn={(id) => drawingMasterDataService.deleteShopSubCategory(id)}
         columns={columns}
         fields={[
-          { name: "subCategoryCode", label: "Sub-category Code", type: "text", required: true },
-          { name: "subCategoryName", label: "Sub-category Name", type: "text", required: true },
-          { name: "description", label: "Description", type: "textarea" },
-          { name: "isActive", label: "Active", type: "checkbox" },
-          { name: "sortOrder", label: "Sort Order", type: "text", required: true },
+          { name: 'subCategoryCode', label: 'Sub-category Code', type: 'text', required: true },
+          { name: 'subCategoryName', label: 'Sub-category Name', type: 'text', required: true },
+          { name: 'description', label: 'Description', type: 'textarea' },
+          { name: 'isActive', label: 'Active', type: 'checkbox' },
+          { name: 'sortOrder', label: 'Sort Order', type: 'text', required: true },
         ]}
         filters={projectFilter}
       />