fix: 품목기준관리 실시간 동기화 수정

- BOM 항목 추가/수정/삭제 시 섹션탭 즉시 반영
- 섹션 복제 시 UI 즉시 업데이트 (null vs undefined 이슈 해결)
- 항목 수정 기능 추가 (useTemplateManagement)
- 실시간 동기화 문서 추가

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/lib/api/error-handler.ts

@@ -46,6 +46,12 @@ export const handleApiError = async (response: Response): Promise<never> => {
 
   // 422 Unprocessable Entity - Validation 에러
   if (response.status === 422) {
+    // 상세 validation 에러 로그 출력
+    console.error('🔴 [API 422 Validation Error]', {
+      message: data.message,
+      errors: data.errors,
+      fullResponse: data
+    });
     throw new ApiError(
       422,
       data.message || '입력값을 확인해주세요.',

src/lib/api/item-master.ts

@@ -10,11 +10,19 @@ import type {
   ItemSectionRequest,
   ItemSectionResponse,
   SectionReorderRequest,
+  IndependentSectionRequest,
+  SectionUsageResponse,
+  LinkSectionRequest,
   ItemFieldRequest,
   ItemFieldResponse,
   FieldReorderRequest,
+  IndependentFieldRequest,
+  FieldUsageResponse,
+  LinkFieldRequest,
   BomItemRequest,
   BomItemResponse,
+  IndependentBomItemRequest,
+  PageStructureResponse,
   SectionTemplateRequest,
   SectionTemplateResponse,
   MasterFieldRequest,
@@ -25,6 +33,11 @@ import type {
   TabColumnUpdateRequest,
   UnitOptionRequest,
   UnitOptionResponse,
+  // 2025-11-27 추가: 엔티티 관계 타입
+  EntityRelationshipResponse,
+  LinkEntityRequest,
+  LinkBomRequest,
+  ReorderRelationshipsRequest,
 } from '@/types/item-master-api';
 import { getAuthHeaders } from './auth-headers';
 import { handleApiError } from './error-handler';
@@ -216,6 +229,212 @@ export const itemMasterApi = {
         throw error;
       }
     },
+
+    /**
+     * 페이지에 섹션 연결
+     * POST /v1/item-master/pages/{id}/link-section
+     * 2025-11-26 신규 API
+     */
+    linkSection: async (pageId: number, data: LinkSectionRequest): Promise<ApiResponse<ItemSectionResponse>> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/pages/${pageId}/link-section`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/pages/${pageId}/link-section`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemSectionResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/pages/${pageId}/link-section`, response.status, result, startTime);
+
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/pages/${pageId}/link-section`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+
+        apiLogger.logError('POST', `${BASE_URL}/item-master/pages/${pageId}/link-section`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 페이지에서 섹션 연결 해제
+     * DELETE /v1/item-master/pages/{id}/unlink-section/{sectionId}
+     * 2025-11-26 신규 API
+     */
+    unlinkSection: async (pageId: number, sectionId: number): Promise<ApiResponse<void>> => {
+      const startTime = apiLogger.logRequest('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-section/${sectionId}`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/pages/${pageId}/unlink-section/${sectionId}`, {
+          method: 'DELETE',
+          headers,
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<void> = await response.json();
+        apiLogger.logResponse('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-section/${sectionId}`, response.status, result, startTime);
+
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-section/${sectionId}`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+
+        apiLogger.logError('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-section/${sectionId}`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 페이지 전체 구조 조회
+     * GET /v1/item-master/pages/{id}/structure
+     * 2025-11-26 신규 API
+     */
+    getStructure: async (pageId: number): Promise<PageStructureResponse> => {
+      const startTime = apiLogger.logRequest('GET', `${BASE_URL}/item-master/pages/${pageId}/structure`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/pages/${pageId}/structure`, {
+          method: 'GET',
+          headers,
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<PageStructureResponse> = await response.json();
+        apiLogger.logResponse('GET', `${BASE_URL}/item-master/pages/${pageId}/structure`, response.status, result, startTime);
+
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', `${BASE_URL}/item-master/pages/${pageId}/structure`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+
+        apiLogger.logError('GET', `${BASE_URL}/item-master/pages/${pageId}/structure`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 페이지 관계 조회
+     * GET /v1/item-master/pages/{id}/relationships
+     * 2025-11-27 신규 API
+     */
+    getRelationships: async (pageId: number): Promise<EntityRelationshipResponse[]> => {
+      const startTime = apiLogger.logRequest('GET', `${BASE_URL}/item-master/pages/${pageId}/relationships`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/pages/${pageId}/relationships`, {
+          method: 'GET',
+          headers,
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<EntityRelationshipResponse[]> = await response.json();
+        apiLogger.logResponse('GET', `${BASE_URL}/item-master/pages/${pageId}/relationships`, response.status, result, startTime);
+
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', `${BASE_URL}/item-master/pages/${pageId}/relationships`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+
+        apiLogger.logError('GET', `${BASE_URL}/item-master/pages/${pageId}/relationships`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 페이지에 필드 직접 연결
+     * POST /v1/item-master/pages/{id}/link-field
+     * 2025-11-27 신규 API
+     */
+    linkField: async (pageId: number, data: LinkEntityRequest): Promise<ApiResponse<ItemFieldResponse>> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/pages/${pageId}/link-field`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/pages/${pageId}/link-field`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemFieldResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/pages/${pageId}/link-field`, response.status, result, startTime);
+
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/pages/${pageId}/link-field`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+
+        apiLogger.logError('POST', `${BASE_URL}/item-master/pages/${pageId}/link-field`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 페이지에서 필드 연결 해제
+     * DELETE /v1/item-master/pages/{id}/unlink-field/{fieldId}
+     * 2025-11-27 신규 API
+     */
+    unlinkField: async (pageId: number, fieldId: number): Promise<ApiResponse<void>> => {
+      const startTime = apiLogger.logRequest('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-field/${fieldId}`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/pages/${pageId}/unlink-field/${fieldId}`, {
+          method: 'DELETE',
+          headers,
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<void> = await response.json();
+        apiLogger.logResponse('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-field/${fieldId}`, response.status, result, startTime);
+
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-field/${fieldId}`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+
+        apiLogger.logError('DELETE', `${BASE_URL}/item-master/pages/${pageId}/unlink-field/${fieldId}`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
   },
 
   // ============================================
@@ -223,7 +442,296 @@ export const itemMasterApi = {
   // ============================================
   sections: {
     /**
-     * 섹션 생성
+     * 독립 섹션 목록 조회
+     * GET /v1/item-master/sections
+     * 2025-11-26 신규 API
+     * @param params.is_template - true: 템플릿만, false: 일반 섹션만, undefined: 전체
+     */
+    list: async (params?: { is_template?: boolean }): Promise<ItemSectionResponse[]> => {
+      const queryParams = new URLSearchParams();
+      if (params?.is_template !== undefined) {
+        queryParams.set('is_template', String(params.is_template));
+      }
+      const queryString = queryParams.toString();
+      const url = `${BASE_URL}/item-master/sections${queryString ? `?${queryString}` : ''}`;
+      const startTime = apiLogger.logRequest('GET', url);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(url, { method: 'GET', headers });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemSectionResponse[]> = await response.json();
+        apiLogger.logResponse('GET', url, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', url, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('GET', url, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 독립 섹션 생성 (페이지에 연결되지 않은 섹션)
+     * POST /v1/item-master/sections
+     * 2025-11-26 신규 API
+     */
+    createIndependent: async (data: IndependentSectionRequest): Promise<ItemSectionResponse> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/sections`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemSectionResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/sections`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/sections`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('POST', `${BASE_URL}/item-master/sections`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션 복제
+     * POST /v1/item-master/sections/{id}/clone
+     * 2025-11-26 신규 API
+     */
+    clone: async (id: number): Promise<ItemSectionResponse> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/sections/${id}/clone`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections/${id}/clone`, { method: 'POST', headers });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemSectionResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/sections/${id}/clone`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/sections/${id}/clone`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('POST', `${BASE_URL}/item-master/sections/${id}/clone`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션 사용처 조회
+     * GET /v1/item-master/sections/{id}/usage
+     * 2025-11-26 신규 API
+     */
+    getUsage: async (id: number): Promise<SectionUsageResponse> => {
+      const startTime = apiLogger.logRequest('GET', `${BASE_URL}/item-master/sections/${id}/usage`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections/${id}/usage`, { method: 'GET', headers });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<SectionUsageResponse> = await response.json();
+        apiLogger.logResponse('GET', `${BASE_URL}/item-master/sections/${id}/usage`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', `${BASE_URL}/item-master/sections/${id}/usage`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('GET', `${BASE_URL}/item-master/sections/${id}/usage`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션에 필드 연결
+     * POST /v1/item-master/sections/{id}/link-field
+     * 2025-11-26 신규 API
+     */
+    linkField: async (sectionId: number, data: LinkFieldRequest): Promise<ApiResponse<ItemFieldResponse>> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-field`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections/${sectionId}/link-field`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemFieldResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-field`, response.status, result, startTime);
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-field`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-field`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션에서 필드 연결 해제
+     * DELETE /v1/item-master/sections/{id}/unlink-field/{fieldId}
+     * 2025-11-26 신규 API
+     */
+    unlinkField: async (sectionId: number, fieldId: number): Promise<ApiResponse<void>> => {
+      const startTime = apiLogger.logRequest('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-field/${fieldId}`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections/${sectionId}/unlink-field/${fieldId}`, {
+          method: 'DELETE',
+          headers,
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<void> = await response.json();
+        apiLogger.logResponse('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-field/${fieldId}`, response.status, result, startTime);
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-field/${fieldId}`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-field/${fieldId}`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션에 BOM 연결
+     * POST /v1/item-master/sections/{id}/link-bom
+     * 2025-11-27 신규 API
+     */
+    linkBom: async (sectionId: number, data: LinkBomRequest): Promise<ApiResponse<BomItemResponse>> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-bom`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections/${sectionId}/link-bom`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<BomItemResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-bom`, response.status, result, startTime);
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-bom`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('POST', `${BASE_URL}/item-master/sections/${sectionId}/link-bom`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션에서 BOM 연결 해제
+     * DELETE /v1/item-master/sections/{id}/unlink-bom/{bomId}
+     * 2025-11-27 신규 API
+     */
+    unlinkBom: async (sectionId: number, bomId: number): Promise<ApiResponse<void>> => {
+      const startTime = apiLogger.logRequest('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-bom/${bomId}`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections/${sectionId}/unlink-bom/${bomId}`, {
+          method: 'DELETE',
+          headers,
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<void> = await response.json();
+        apiLogger.logResponse('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-bom/${bomId}`, response.status, result, startTime);
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-bom/${bomId}`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('DELETE', `${BASE_URL}/item-master/sections/${sectionId}/unlink-bom/${bomId}`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션 관계 조회
+     * GET /v1/item-master/sections/{id}/relationships
+     * 2025-11-27 신규 API
+     */
+    getRelationships: async (sectionId: number): Promise<EntityRelationshipResponse[]> => {
+      const startTime = apiLogger.logRequest('GET', `${BASE_URL}/item-master/sections/${sectionId}/relationships`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/sections/${sectionId}/relationships`, {
+          method: 'GET',
+          headers,
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<EntityRelationshipResponse[]> = await response.json();
+        apiLogger.logResponse('GET', `${BASE_URL}/item-master/sections/${sectionId}/relationships`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', `${BASE_URL}/item-master/sections/${sectionId}/relationships`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('GET', `${BASE_URL}/item-master/sections/${sectionId}/relationships`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 섹션 생성 (페이지 하위)
      * POST /v1/item-master/pages/{pageId}/sections
      */
     create: async (pageId: number, data: ItemSectionRequest): Promise<ApiResponse<ItemSectionResponse>> => {
@@ -363,7 +871,127 @@ export const itemMasterApi = {
   // ============================================
   fields: {
     /**
-     * 필드 생성
+     * 독립 필드 목록 조회
+     * GET /v1/item-master/fields
+     * 2025-11-26 신규 API
+     */
+    list: async (): Promise<ItemFieldResponse[]> => {
+      const startTime = apiLogger.logRequest('GET', `${BASE_URL}/item-master/fields`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/fields`, { method: 'GET', headers });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemFieldResponse[]> = await response.json();
+        apiLogger.logResponse('GET', `${BASE_URL}/item-master/fields`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', `${BASE_URL}/item-master/fields`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('GET', `${BASE_URL}/item-master/fields`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 독립 필드 생성
+     * POST /v1/item-master/fields
+     * 2025-11-26 신규 API
+     */
+    createIndependent: async (data: IndependentFieldRequest): Promise<ItemFieldResponse> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/fields`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/fields`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemFieldResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/fields`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/fields`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('POST', `${BASE_URL}/item-master/fields`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 필드 복제
+     * POST /v1/item-master/fields/{id}/clone
+     * 2025-11-26 신규 API
+     */
+    clone: async (id: number): Promise<ItemFieldResponse> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/fields/${id}/clone`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/fields/${id}/clone`, { method: 'POST', headers });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<ItemFieldResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/fields/${id}/clone`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/fields/${id}/clone`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('POST', `${BASE_URL}/item-master/fields/${id}/clone`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 필드 사용처 조회
+     * GET /v1/item-master/fields/{id}/usage
+     * 2025-11-26 신규 API
+     */
+    getUsage: async (id: number): Promise<FieldUsageResponse> => {
+      const startTime = apiLogger.logRequest('GET', `${BASE_URL}/item-master/fields/${id}/usage`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/fields/${id}/usage`, { method: 'GET', headers });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<FieldUsageResponse> = await response.json();
+        apiLogger.logResponse('GET', `${BASE_URL}/item-master/fields/${id}/usage`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', `${BASE_URL}/item-master/fields/${id}/usage`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('GET', `${BASE_URL}/item-master/fields/${id}/usage`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 필드 생성 (섹션 하위)
      * POST /v1/item-master/sections/{sectionId}/fields
      */
     create: async (sectionId: number, data: ItemFieldRequest): Promise<ApiResponse<ItemFieldResponse>> => {
@@ -503,7 +1131,69 @@ export const itemMasterApi = {
   // ============================================
   bomItems: {
     /**
-     * BOM 항목 생성
+     * 독립 BOM 목록 조회
+     * GET /v1/item-master/bom-items
+     * 2025-11-26 신규 API
+     */
+    list: async (): Promise<BomItemResponse[]> => {
+      const startTime = apiLogger.logRequest('GET', `${BASE_URL}/item-master/bom-items`);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/bom-items`, { method: 'GET', headers });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<BomItemResponse[]> = await response.json();
+        apiLogger.logResponse('GET', `${BASE_URL}/item-master/bom-items`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('GET', `${BASE_URL}/item-master/bom-items`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('GET', `${BASE_URL}/item-master/bom-items`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * 독립 BOM 항목 생성
+     * POST /v1/item-master/bom-items
+     * 2025-11-26 신규 API
+     */
+    createIndependent: async (data: IndependentBomItemRequest): Promise<BomItemResponse> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/bom-items`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/bom-items`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<BomItemResponse> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/bom-items`, response.status, result, startTime);
+        return result.data;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/bom-items`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+        apiLogger.logError('POST', `${BASE_URL}/item-master/bom-items`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+
+    /**
+     * BOM 항목 생성 (섹션 하위)
      * POST /v1/item-master/sections/{sectionId}/bom-items
      */
     create: async (sectionId: number, data: BomItemRequest): Promise<ApiResponse<BomItemResponse>> => {
@@ -745,11 +1435,56 @@ export const itemMasterApi = {
   },
 
   // ============================================
-  // 마스터 필드
+  // 엔티티 관계 (Entity Relationships)
+  // 2025-11-27 신규: 링크 테이블 기반 순서 변경
+  // ============================================
+  relationships: {
+    /**
+     * 관계 순서 변경
+     * POST /v1/item-master/relationships/reorder
+     * 2025-11-27 신규 API
+     */
+    reorder: async (data: ReorderRelationshipsRequest): Promise<ApiResponse<EntityRelationshipResponse[]>> => {
+      const startTime = apiLogger.logRequest('POST', `${BASE_URL}/item-master/relationships/reorder`, data);
+
+      try {
+        const headers = getAuthHeaders();
+        const response = await fetch(`${BASE_URL}/item-master/relationships/reorder`, {
+          method: 'POST',
+          headers,
+          body: JSON.stringify(data),
+        });
+
+        if (!response.ok) {
+          await handleApiError(response);
+        }
+
+        const result: ApiResponse<EntityRelationshipResponse[]> = await response.json();
+        apiLogger.logResponse('POST', `${BASE_URL}/item-master/relationships/reorder`, response.status, result, startTime);
+
+        return result;
+      } catch (error) {
+        if (error instanceof TypeError) {
+          apiLogger.logError('POST', `${BASE_URL}/item-master/relationships/reorder`, error, undefined, startTime);
+          throw new Error('네트워크 연결을 확인해주세요. 서버에 연결할 수 없습니다.');
+        }
+
+        apiLogger.logError('POST', `${BASE_URL}/item-master/relationships/reorder`, error as Error, undefined, startTime);
+        throw error;
+      }
+    },
+  },
+
+  // ============================================
+  // 마스터 필드 (DEPRECATED)
+  // 2025-11-27: item_master_fields가 item_fields로 통합됨
+  // 독립 필드 = item_fields WHERE section_id IS NULL
+  // fields API 사용 권장 (fields.list, fields.createIndependent 등)
   // ============================================
   masterFields: {
     /**
      * 마스터 필드 목록 조회
+     * @deprecated 2025-11-27: fields.list() 사용 권장
      * GET /v1/item-master/master-fields
      * Note: init API에 포함되므로 일반적으로 직접 호출 불필요
      */
@@ -784,6 +1519,7 @@ export const itemMasterApi = {
 
     /**
      * 마스터 필드 생성
+     * @deprecated 2025-11-27: fields.createIndependent() 사용 권장
      * POST /v1/item-master/master-fields
      */
     create: async (data: MasterFieldRequest): Promise<ApiResponse<MasterFieldResponse>> => {
@@ -818,6 +1554,7 @@ export const itemMasterApi = {
 
     /**
      * 마스터 필드 수정
+     * @deprecated 2025-11-27: fields.update() 사용 권장
      * PUT /v1/item-master/master-fields/{id}
      */
     update: async (id: number, data: Partial<MasterFieldRequest>): Promise<ApiResponse<MasterFieldResponse>> => {
@@ -852,6 +1589,7 @@ export const itemMasterApi = {
 
     /**
      * 마스터 필드 삭제
+     * @deprecated 2025-11-27: fields.delete() 사용 권장
      * DELETE /v1/item-master/master-fields/{id}
      */
     delete: async (id: number): Promise<ApiResponse<void>> => {

src/lib/api/transformers.ts

@@ -44,36 +44,16 @@ const SECTION_TYPE_REVERSE_MAP: Record<string, 'fields' | 'bom'> = {
   CUSTOM: 'fields', // CUSTOM은 fields로 매핑
 };
 
-/**
- * API field_type → Frontend field_type 변환
- * API: 'textbox' | 'number' | 'dropdown' | 'checkbox' | 'date' | 'textarea'
- * Frontend: 'TEXT' | 'NUMBER' | 'DATE' | 'SELECT' | 'TEXTAREA' | 'CHECKBOX'
- */
-const FIELD_TYPE_MAP: Record<
-  string,
-  'TEXT' | 'NUMBER' | 'DATE' | 'SELECT' | 'TEXTAREA' | 'CHECKBOX'
-> = {
-  textbox: 'TEXT',
-  number: 'NUMBER',
-  dropdown: 'SELECT',
-  checkbox: 'CHECKBOX',
-  date: 'DATE',
-  textarea: 'TEXTAREA',
-};
+// 2025-11-26: field_type은 API와 Frontend가 동일한 값을 사용하므로 변환 불필요
+// API & Frontend: 'textbox' | 'number' | 'dropdown' | 'checkbox' | 'date' | 'textarea'
+type FieldType = 'textbox' | 'number' | 'dropdown' | 'checkbox' | 'date' | 'textarea';
 
 /**
- * Frontend field_type → API field_type 변환
+ * field_type 기본값 반환 (알 수 없는 값일 경우)
  */
-const FIELD_TYPE_REVERSE_MAP: Record<
-  string,
-  'textbox' | 'number' | 'dropdown' | 'checkbox' | 'date' | 'textarea'
-> = {
-  TEXT: 'textbox',
-  NUMBER: 'number',
-  SELECT: 'dropdown',
-  CHECKBOX: 'checkbox',
-  DATE: 'date',
-  TEXTAREA: 'textarea',
+const getFieldType = (type: string): FieldType => {
+  const validTypes: FieldType[] = ['textbox', 'number', 'dropdown', 'checkbox', 'date', 'textarea'];
+  return validTypes.includes(type as FieldType) ? (type as FieldType) : 'textbox';
 };
 
 // ============================================
@@ -91,8 +71,10 @@ export const transformPageResponse = (
     tenant_id: response.tenant_id,
     page_name: response.page_name,
     item_type: response.item_type as 'FG' | 'PT' | 'SM' | 'RM' | 'CS',
-    absolute_path: response.absolute_path,
+    description: response.description ?? null, // 2025-11-26 추가
+    absolute_path: response.absolute_path || '', // null일 경우 빈 문자열
     is_active: response.is_active,
+    order_no: response.order_no ?? 0, // 2025-11-26 추가
     sections: response.sections?.map(transformSectionResponse) || [],
     created_by: response.created_by,
     updated_by: response.updated_by,
@@ -104,6 +86,7 @@ export const transformPageResponse = (
 /**
  * ItemSectionResponse → ItemSection 변환
  * 주요 변환: type → section_type, 값 변환 (fields → BASIC, bom → BOM)
+ * 2025-11-26: group_id, is_template, is_default, description 추가 (section_templates 통합)
  */
 export const transformSectionResponse = (
   response: ItemSectionResponse
@@ -111,12 +94,17 @@ export const transformSectionResponse = (
   return {
     id: response.id,
     tenant_id: response.tenant_id,
-    page_id: response.page_id,
+    group_id: response.group_id, // 2025-11-26 추가: 독립 섹션 그룹화용
+    page_id: response.page_id, // null이면 독립 섹션
     title: response.title,
     section_type: SECTION_TYPE_MAP[response.type] || 'BASIC', // 타입 값 변환
+    description: response.description, // 2025-11-26 추가
     order_no: response.order_no,
+    is_template: response.is_template, // 2025-11-26 추가: 템플릿 여부 (section_templates 통합)
+    is_default: response.is_default, // 2025-11-26 추가: 기본 템플릿 여부
     fields: response.fields?.map(transformFieldResponse) || [],
-    bom_items: response.bomItems?.map(transformBomItemResponse) || [],
+    // 2025-11-27: 백엔드가 bom_items (snake_case)로 반환하므로 둘 다 체크
+    bom_items: (response.bom_items || response.bomItems)?.map(transformBomItemResponse) || [],
     created_by: response.created_by,
     updated_by: response.updated_by,
     created_at: response.created_at,
@@ -126,7 +114,7 @@ export const transformSectionResponse = (
 
 /**
  * ItemFieldResponse → ItemField 변환
- * 주요 변환: field_type 값 변환 (textbox → TEXT, dropdown → SELECT 등)
+ * 2025-11-26: field_type은 API와 동일한 값 사용 (변환 불필요)
  */
 export const transformFieldResponse = (
   response: ItemFieldResponse
@@ -136,7 +124,7 @@ export const transformFieldResponse = (
     tenant_id: response.tenant_id,
     section_id: response.section_id,
     field_name: response.field_name,
-    field_type: FIELD_TYPE_MAP[response.field_type] || 'TEXT', // 타입 값 변환
+    field_type: getFieldType(response.field_type), // API와 동일한 타입
     order_no: response.order_no,
     is_required: response.is_required,
     placeholder: response.placeholder,
@@ -200,7 +188,7 @@ export const transformSectionTemplateResponse = (
 
 /**
  * MasterFieldResponse → ItemMasterField 변환
- * 주요 변환: field_type 값 변환 (textbox → TEXT, dropdown → SELECT 등)
+ * 2025-11-26: field_type은 API와 동일한 값 사용, 속성명도 API와 통일
  */
 export const transformMasterFieldResponse = (
   response: MasterFieldResponse
@@ -209,11 +197,14 @@ export const transformMasterFieldResponse = (
     id: response.id,
     tenant_id: response.tenant_id,
     field_name: response.field_name,
-    field_type: FIELD_TYPE_MAP[response.field_type] || 'TEXT', // 타입 값 변환
+    field_type: getFieldType(response.field_type), // API와 동일한 타입
     category: response.category,
     description: response.description,
-    default_validation: response.validation_rules, // 필드명 매핑
-    default_properties: response.properties, // 필드명 매핑
+    is_common: response.is_common ?? false, // 공통 필드 여부
+    default_value: response.default_value ?? null, // 기본값
+    options: response.options ?? null, // dropdown 옵션
+    validation_rules: response.validation_rules ?? null, // 검증 규칙
+    properties: response.properties ?? null, // 추가 속성
     created_by: response.created_by,
     updated_by: response.updated_by,
     created_at: response.created_at,
@@ -242,14 +233,12 @@ export const transformSectionToRequest = (
 
 /**
  * ItemField → ItemFieldRequest 변환
- * 주요 변환: field_type 값 역변환 (TEXT → textbox, SELECT → dropdown 등)
+ * 2025-11-26: field_type은 API와 동일한 값 사용 (변환 불필요)
  */
 export const transformFieldToRequest = (field: Partial<ItemField>) => {
   return {
     field_name: field.field_name || '',
-    field_type: field.field_type
-      ? FIELD_TYPE_REVERSE_MAP[field.field_type] || 'textbox'
-      : 'textbox',
+    field_type: field.field_type || 'textbox', // API와 동일한 타입
     is_required: field.is_required ?? false,
     placeholder: field.placeholder || null,
     default_value: field.default_value || null,
@@ -295,23 +284,21 @@ export const transformSectionTemplateToRequest = (
 
 /**
  * ItemMasterField → MasterFieldRequest 변환
- * 주요 변환: field_type 값 역변환, default_validation/properties 필드명 변환
+ * 2025-11-26: field_type과 속성명 모두 API와 동일하게 통일
  */
 export const transformMasterFieldToRequest = (
   field: Partial<ItemMasterField>
 ) => {
   return {
     field_name: field.field_name || '',
-    field_type: field.field_type
-      ? FIELD_TYPE_REVERSE_MAP[field.field_type] || 'textbox'
-      : 'textbox',
+    field_type: field.field_type || 'textbox', // API와 동일한 타입
     category: field.category || undefined,
     description: field.description || undefined,
-    is_common: false, // 기본값
-    default_value: undefined,
-    options: undefined,
-    validation_rules: field.default_validation || undefined, // 필드명 역변환
-    properties: field.default_properties || undefined, // 필드명 역변환
+    is_common: field.is_common ?? false,
+    default_value: field.default_value || undefined,
+    options: field.options || undefined,
+    validation_rules: field.validation_rules || undefined, // API와 동일
+    properties: field.properties || undefined, // API와 동일
   };
 };
 
@@ -323,8 +310,9 @@ export const transformMasterFieldToRequest = (
  * 여러 페이지 응답을 한번에 변환
  */
 export const transformPagesResponse = (
-  responses: ItemPageResponse[]
+  responses: ItemPageResponse[] | undefined | null
 ): ItemPage[] => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformPageResponse);
 };
 
@@ -332,8 +320,9 @@ export const transformPagesResponse = (
  * 여러 섹션 응답을 한번에 변환
  */
 export const transformSectionsResponse = (
-  responses: ItemSectionResponse[]
+  responses: ItemSectionResponse[] | undefined | null
 ): ItemSection[] => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformSectionResponse);
 };
 
@@ -341,8 +330,9 @@ export const transformSectionsResponse = (
  * 여러 필드 응답을 한번에 변환
  */
 export const transformFieldsResponse = (
-  responses: ItemFieldResponse[]
+  responses: ItemFieldResponse[] | undefined | null
 ): ItemField[] => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformFieldResponse);
 };
 
@@ -350,8 +340,9 @@ export const transformFieldsResponse = (
  * 여러 BOM 아이템 응답을 한번에 변환
  */
 export const transformBomItemsResponse = (
-  responses: BomItemResponse[]
+  responses: BomItemResponse[] | undefined | null
 ): BOMItem[] => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformBomItemResponse);
 };
 
@@ -359,8 +350,9 @@ export const transformBomItemsResponse = (
  * 여러 섹션 템플릿 응답을 한번에 변환
  */
 export const transformSectionTemplatesResponse = (
-  responses: SectionTemplateResponse[]
+  responses: SectionTemplateResponse[] | undefined | null
 ): SectionTemplate[] => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformSectionTemplateResponse);
 };
 
@@ -368,8 +360,9 @@ export const transformSectionTemplatesResponse = (
  * 여러 마스터 필드 응답을 한번에 변환
  */
 export const transformMasterFieldsResponse = (
-  responses: MasterFieldResponse[]
+  responses: MasterFieldResponse[] | undefined | null
 ): ItemMasterField[] => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformMasterFieldResponse);
 };
 
@@ -406,8 +399,9 @@ export const transformCustomTabResponse = (
  * 여러 단위 옵션 응답을 한번에 변환
  */
 export const transformUnitOptionsResponse = (
-  responses: UnitOptionResponse[]
+  responses: UnitOptionResponse[] | undefined | null
 ) => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformUnitOptionResponse);
 };
 
@@ -415,7 +409,43 @@ export const transformUnitOptionsResponse = (
  * 여러 커스텀 탭 응답을 한번에 변환
  */
 export const transformCustomTabsResponse = (
-  responses: CustomTabResponse[]
+  responses: CustomTabResponse[] | undefined | null
 ) => {
+  if (!responses || !Array.isArray(responses)) return [];
   return responses.map(transformCustomTabResponse);
+};
+
+/**
+ * ItemSectionResponse → SectionTemplate 변환
+ * 2025-11-26: 백엔드가 sectionTemplates 대신 sections를 반환하는 경우 사용
+ * is_template=true인 섹션을 SectionTemplate 형식으로 변환
+ */
+export const transformSectionTemplateFromSection = (
+  response: ItemSectionResponse
+): SectionTemplate => {
+  return {
+    id: response.id,
+    tenant_id: response.tenant_id,
+    template_name: response.title, // title → template_name
+    section_type: SECTION_TYPE_MAP[response.type] || 'BASIC', // type → section_type
+    description: response.description,
+    default_fields: null, // API 응답에 없으므로 null
+    // 필드 변환은 별도 처리 필요 (fields가 있으면 TemplateField로 변환)
+    fields: response.fields?.map(field => ({
+      id: field.id.toString(),
+      name: field.field_name,
+      fieldKey: field.field_name.toLowerCase().replace(/\s+/g, '_'),
+      property: {
+        inputType: getFieldType(field.field_type),
+        required: field.is_required,
+        options: field.options?.map((opt: { label: string; value: string }) => opt.label || opt.value),
+      },
+      description: field.placeholder || undefined,
+    })),
+    bomItems: response.bomItems?.map(transformBomItemResponse),
+    created_by: response.created_by,
+    updated_by: response.updated_by,
+    created_at: response.created_at,
+    updated_at: response.updated_at,
+  };
 };