diff --git a/rsconcept/frontend/src/backend/api-transport.ts b/rsconcept/frontend/src/backend/api-transport.ts
index ef0add70..8a88c449 100644
--- a/rsconcept/frontend/src/backend/api-transport.ts
+++ b/rsconcept/frontend/src/backend/api-transport.ts
@@ -8,6 +8,7 @@ import { type z, ZodError } from 'zod';
 import { buildConstants } from '@/utils/build-constants';
 import { PARAMETER } from '@/utils/constants';
 import { errorMsg } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 import { extractErrorMessage } from '@/utils/utils';
 
 export { AxiosError } from 'axios';
@@ -58,7 +59,7 @@ export function axiosGet<ResponseData>({ endpoint, options, schema }: IAxiosGetR
     .get<ResponseData>(endpoint, options)
     .then(response => {
       schema?.parse(response.data);
-      return response.data;
+      return response.data as RO<ResponseData>;
     })
     .catch((error: Error | AxiosError) => {
       // Note: Ignore cancellation errors
@@ -81,7 +82,7 @@ export function axiosPost<RequestData, ResponseData = void>({
     .then(response => {
       schema?.parse(response.data);
       notifySuccess(response.data, request?.successMessage);
-      return response.data;
+      return response.data as RO<ResponseData>;
     })
     .catch((error: Error | AxiosError | ZodError) => {
       notifyError(error);
@@ -100,7 +101,7 @@ export function axiosDelete<RequestData, ResponseData = void>({
     .then(response => {
       schema?.parse(response.data);
       notifySuccess(response.data, request?.successMessage);
-      return response.data;
+      return response.data as RO<ResponseData>;
     })
     .catch((error: Error | AxiosError | ZodError) => {
       notifyError(error);
@@ -119,7 +120,7 @@ export function axiosPatch<RequestData, ResponseData = void>({
     .then(response => {
       schema?.parse(response.data);
       notifySuccess(response.data, request?.successMessage);
-      return response.data;
+      return response.data as RO<ResponseData>;
     })
     .catch((error: Error | AxiosError | ZodError) => {
       notifyError(error);
diff --git a/rsconcept/frontend/src/components/input/combo-box.tsx b/rsconcept/frontend/src/components/input/combo-box.tsx
index baeecb38..714ad927 100644
--- a/rsconcept/frontend/src/components/input/combo-box.tsx
+++ b/rsconcept/frontend/src/components/input/combo-box.tsx
@@ -11,7 +11,7 @@ import { cn } from '../utils';
 
 interface ComboBoxProps<Option> extends Styling {
   id?: string;
-  items?: Option[];
+  items?: readonly Option[];
   value: Option | null;
   onChange: (newValue: Option | null) => void;
 
diff --git a/rsconcept/frontend/src/features/library/backend/use-set-access-policy.tsx b/rsconcept/frontend/src/features/library/backend/use-set-access-policy.tsx
index ae6f0dcb..a411349e 100644
--- a/rsconcept/frontend/src/features/library/backend/use-set-access-policy.tsx
+++ b/rsconcept/frontend/src/features/library/backend/use-set-access-policy.tsx
@@ -4,6 +4,7 @@ import { type IOperationSchemaDTO } from '@/features/oss';
 import { type IRSFormDTO } from '@/features/rsform';
 
 import { KEYS } from '@/backend/configuration';
+import { type RO } from '@/utils/meta';
 
 import { libraryApi } from './api';
 import { type AccessPolicy, type ILibraryItem } from './types';
@@ -38,7 +39,7 @@ export const useSetAccessPolicy = () => {
       client.setQueryData(rsKey, (prev: IRSFormDTO | undefined) =>
         !prev ? undefined : { ...prev, access_policy: variables.policy }
       );
-      client.setQueryData(libraryKey, (prev: ILibraryItem[] | undefined) =>
+      client.setQueryData(libraryKey, (prev: RO<ILibraryItem[]> | undefined) =>
         prev?.map(item => (item.id === variables.itemID ? { ...item, access_policy: variables.policy } : item))
       );
     },
diff --git a/rsconcept/frontend/src/features/library/backend/use-set-location.tsx b/rsconcept/frontend/src/features/library/backend/use-set-location.tsx
index 4f2b36f4..323c5f58 100644
--- a/rsconcept/frontend/src/features/library/backend/use-set-location.tsx
+++ b/rsconcept/frontend/src/features/library/backend/use-set-location.tsx
@@ -4,6 +4,7 @@ import { type IOperationSchemaDTO } from '@/features/oss';
 import { type IRSFormDTO } from '@/features/rsform';
 
 import { KEYS } from '@/backend/configuration';
+import { type RO } from '@/utils/meta';
 
 import { libraryApi } from './api';
 import { type ILibraryItem } from './types';
@@ -38,7 +39,7 @@ export const useSetLocation = () => {
       client.setQueryData(rsKey, (prev: IRSFormDTO | undefined) =>
         !prev ? undefined : { ...prev, location: variables.location }
       );
-      client.setQueryData(libraryKey, (prev: ILibraryItem[] | undefined) =>
+      client.setQueryData(libraryKey, (prev: RO<ILibraryItem[]> | undefined) =>
         prev?.map(item => (item.id === variables.itemID ? { ...item, location: variables.location } : item))
       );
     },
diff --git a/rsconcept/frontend/src/features/library/backend/use-set-owner.tsx b/rsconcept/frontend/src/features/library/backend/use-set-owner.tsx
index 1f3faf11..4921f016 100644
--- a/rsconcept/frontend/src/features/library/backend/use-set-owner.tsx
+++ b/rsconcept/frontend/src/features/library/backend/use-set-owner.tsx
@@ -4,6 +4,7 @@ import { type IOperationSchemaDTO } from '@/features/oss';
 import { type IRSFormDTO } from '@/features/rsform';
 
 import { KEYS } from '@/backend/configuration';
+import { type RO } from '@/utils/meta';
 
 import { libraryApi } from './api';
 import { type ILibraryItem } from './types';
@@ -38,7 +39,7 @@ export const useSetOwner = () => {
       client.setQueryData(rsKey, (prev: IRSFormDTO | undefined) =>
         !prev ? undefined : { ...prev, owner: variables.owner }
       );
-      client.setQueryData(libraryKey, (prev: ILibraryItem[] | undefined) =>
+      client.setQueryData(libraryKey, (prev: RO<ILibraryItem[]> | undefined) =>
         prev?.map(item => (item.id === variables.itemID ? { ...item, owner: variables.owner } : item))
       );
     },
diff --git a/rsconcept/frontend/src/features/library/backend/use-update-item.tsx b/rsconcept/frontend/src/features/library/backend/use-update-item.tsx
index 234ee825..70ba76fe 100644
--- a/rsconcept/frontend/src/features/library/backend/use-update-item.tsx
+++ b/rsconcept/frontend/src/features/library/backend/use-update-item.tsx
@@ -4,6 +4,7 @@ import { type IOperationSchemaDTO } from '@/features/oss';
 import { type IRSFormDTO } from '@/features/rsform';
 
 import { KEYS } from '@/backend/configuration';
+import { type RO } from '@/utils/meta';
 
 import { libraryApi } from './api';
 import { type ILibraryItem, type IUpdateLibraryItemDTO, LibraryItemType } from './types';
@@ -20,7 +21,7 @@ export const useUpdateItem = () => {
         data.item_type === LibraryItemType.RSFORM
           ? KEYS.composite.rsItem({ itemID: data.id })
           : KEYS.composite.ossItem({ itemID: data.id });
-      client.setQueryData(libraryKey, (prev: ILibraryItem[] | undefined) =>
+      client.setQueryData(libraryKey, (prev: RO<ILibraryItem[]> | undefined) =>
         prev?.map(item => (item.id === data.id ? data : item))
       );
       client.setQueryData(itemKey, (prev: IRSFormDTO | IOperationSchemaDTO | undefined) =>
diff --git a/rsconcept/frontend/src/features/library/backend/use-update-timestamp.tsx b/rsconcept/frontend/src/features/library/backend/use-update-timestamp.tsx
index 183d66e1..4269749c 100644
--- a/rsconcept/frontend/src/features/library/backend/use-update-timestamp.tsx
+++ b/rsconcept/frontend/src/features/library/backend/use-update-timestamp.tsx
@@ -1,5 +1,7 @@
 import { useQueryClient } from '@tanstack/react-query';
 
+import { type RO } from '@/utils/meta';
+
 import { type ILibraryItem } from './types';
 import { useLibraryListKey } from './use-library';
 
@@ -10,7 +12,7 @@ export function useUpdateTimestamp() {
     updateTimestamp: (target: number) =>
       client.setQueryData(
         libraryKey, //
-        (prev: ILibraryItem[] | undefined) =>
+        (prev: RO<ILibraryItem[]> | undefined) =>
           prev?.map(item => (item.id === target ? { ...item, time_update: Date() } : item))
       )
   };
diff --git a/rsconcept/frontend/src/features/library/pages/library-page/table-library-items.tsx b/rsconcept/frontend/src/features/library/pages/library-page/table-library-items.tsx
index b78fd48c..18b848a8 100644
--- a/rsconcept/frontend/src/features/library/pages/library-page/table-library-items.tsx
+++ b/rsconcept/frontend/src/features/library/pages/library-page/table-library-items.tsx
@@ -9,6 +9,7 @@ import { DataTable, type IConditionalStyle, type VisibilityState } from '@/compo
 import { useWindowSize } from '@/hooks/use-window-size';
 import { useFitHeight } from '@/stores/app-layout';
 import { usePreferencesStore } from '@/stores/preferences';
+import { type RO } from '@/utils/meta';
 
 import { type ILibraryItem, LibraryItemType } from '../../backend/types';
 import { useLibrarySearchStore } from '../../stores/library-search';
@@ -16,7 +17,7 @@ import { useLibrarySearchStore } from '../../stores/library-search';
 import { useLibraryColumns } from './use-library-columns';
 
 interface TableLibraryItemsProps {
-  items: ILibraryItem[];
+  items: RO<ILibraryItem[]>;
 }
 
 export function TableLibraryItems({ items }: TableLibraryItemsProps) {
@@ -55,7 +56,7 @@ export function TableLibraryItems({ items }: TableLibraryItemsProps) {
     <DataTable
       id='library_data'
       columns={columns}
-      data={items}
+      data={items as ILibraryItem[]}
       headPosition='0'
       className={clsx('cc-scroll-y h-fit text-xs sm:text-sm border-b', folderMode && 'border-l')}
       style={{ maxHeight: tableHeight }}
diff --git a/rsconcept/frontend/src/features/library/pages/library-page/use-library-columns.tsx b/rsconcept/frontend/src/features/library/pages/library-page/use-library-columns.tsx
index 2c283cca..591d906f 100644
--- a/rsconcept/frontend/src/features/library/pages/library-page/use-library-columns.tsx
+++ b/rsconcept/frontend/src/features/library/pages/library-page/use-library-columns.tsx
@@ -6,12 +6,13 @@ import { MiniButton } from '@/components/control';
 import { createColumnHelper } from '@/components/data-table';
 import { IconFolderTree } from '@/components/icons';
 import { useWindowSize } from '@/hooks/use-window-size';
+import { type RO } from '@/utils/meta';
 
 import { type ILibraryItem } from '../../backend/types';
 import { BadgeLocation } from '../../components/badge-location';
 import { useLibrarySearchStore } from '../../stores/library-search';
 
-const columnHelper = createColumnHelper<ILibraryItem>();
+const columnHelper = createColumnHelper<RO<ILibraryItem>>();
 
 export function useLibraryColumns() {
   const { isSmall } = useWindowSize();
diff --git a/rsconcept/frontend/src/features/oss/backend/oss-loader.ts b/rsconcept/frontend/src/features/oss/backend/oss-loader.ts
index d8444a07..5ef5123f 100644
--- a/rsconcept/frontend/src/features/oss/backend/oss-loader.ts
+++ b/rsconcept/frontend/src/features/oss/backend/oss-loader.ts
@@ -5,6 +5,7 @@
 import { type ILibraryItem } from '@/features/library';
 
 import { Graph } from '@/models/graph';
+import { type RO } from '@/utils/meta';
 
 import { type IBlock, type IOperation, type IOperationSchema, type IOperationSchemaStats } from '../models/oss';
 import { BLOCK_NODE_MIN_HEIGHT, BLOCK_NODE_MIN_WIDTH } from '../pages/oss-page/editor-oss-graph/graph/block-node';
@@ -19,9 +20,9 @@ export class OssLoader {
   private operationByID = new Map<number, IOperation>();
   private blockByID = new Map<number, IBlock>();
   private schemaIDs: number[] = [];
-  private items: ILibraryItem[];
+  private items: RO<ILibraryItem[]>;
 
-  constructor(input: IOperationSchemaDTO, items: ILibraryItem[]) {
+  constructor(input: RO<IOperationSchemaDTO>, items: RO<ILibraryItem[]>) {
     this.oss = structuredClone(input) as IOperationSchema;
     this.items = items;
   }
diff --git a/rsconcept/frontend/src/features/oss/backend/use-update-layout.tsx b/rsconcept/frontend/src/features/oss/backend/use-update-layout.tsx
index 724865b9..d1d7b7b3 100644
--- a/rsconcept/frontend/src/features/oss/backend/use-update-layout.tsx
+++ b/rsconcept/frontend/src/features/oss/backend/use-update-layout.tsx
@@ -3,6 +3,7 @@ import { useMutation, useQueryClient } from '@tanstack/react-query';
 import { useUpdateTimestamp } from '@/features/library/backend/use-update-timestamp';
 
 import { KEYS } from '@/backend/configuration';
+import { type RO } from '@/utils/meta';
 
 import { ossApi } from './api';
 import { type IOperationSchemaDTO, type IOssLayout } from './types';
@@ -17,7 +18,7 @@ export const useUpdateLayout = () => {
       updateTimestamp(variables.itemID);
       client.setQueryData(
         ossApi.getOssQueryOptions({ itemID: variables.itemID }).queryKey,
-        (prev: IOperationSchemaDTO | undefined) =>
+        (prev: RO<IOperationSchemaDTO> | undefined) =>
           !prev
             ? prev
             : {
diff --git a/rsconcept/frontend/src/features/oss/components/pick-contents.tsx b/rsconcept/frontend/src/features/oss/components/pick-contents.tsx
index b9b0b56c..ca4103ba 100644
--- a/rsconcept/frontend/src/features/oss/components/pick-contents.tsx
+++ b/rsconcept/frontend/src/features/oss/components/pick-contents.tsx
@@ -9,9 +9,10 @@ import { ComboBox } from '@/components/input/combo-box';
 import { type Styling } from '@/components/props';
 import { cn } from '@/components/utils';
 import { NoData } from '@/components/view';
+import { type RO } from '@/utils/meta';
 
 import { labelOssItem } from '../labels';
-import { type IBlock, type IOperation, type IOperationSchema } from '../models/oss';
+import { type IOperationSchema, type IOssItem } from '../models/oss';
 import { getItemID, isOperation } from '../models/oss-api';
 
 const SELECTION_CLEAR_TIMEOUT = 1000;
@@ -25,7 +26,7 @@ interface PickMultiOperationProps extends Styling {
   disallowBlocks?: boolean;
 }
 
-const columnHelper = createColumnHelper<IOperation | IBlock>();
+const columnHelper = createColumnHelper<RO<IOssItem>>();
 
 export function PickContents({
   rows,
@@ -40,7 +41,7 @@ export function PickContents({
   const selectedItems = value
     .map(itemID => (itemID > 0 ? schema.operationByID.get(itemID) : schema.blockByID.get(-itemID)))
     .filter(item => item !== undefined);
-  const [lastSelected, setLastSelected] = useState<IOperation | IBlock | null>(null);
+  const [lastSelected, setLastSelected] = useState<RO<IOssItem> | null>(null);
   const items = [
     ...(disallowBlocks ? [] : schema.blocks.filter(item => !value.includes(-item.id) && !exclude?.includes(-item.id))),
     ...schema.operations.filter(item => !value.includes(item.id) && !exclude?.includes(item.id))
@@ -50,7 +51,7 @@ export function PickContents({
     onChange(value.filter(item => item !== target));
   }
 
-  function handleSelect(target: IOperation | IBlock | null) {
+  function handleSelect(target: RO<IOssItem> | null) {
     if (target) {
       setLastSelected(target);
       onChange([...value, getItemID(target)]);
diff --git a/rsconcept/frontend/src/features/oss/labels.ts b/rsconcept/frontend/src/features/oss/labels.ts
index 44142007..47ac360c 100644
--- a/rsconcept/frontend/src/features/oss/labels.ts
+++ b/rsconcept/frontend/src/features/oss/labels.ts
@@ -1,3 +1,5 @@
+import { type RO } from '@/utils/meta';
+
 import { OperationType } from './backend/types';
 import {
   type IOperation,
@@ -26,7 +28,7 @@ export function describeOperationType(itemType: OperationType): string {
 }
 
 /** Generates error description for {@link ISubstitutionErrorDescription}. */
-export function describeSubstitutionError(error: ISubstitutionErrorDescription): string {
+export function describeSubstitutionError(error: RO<ISubstitutionErrorDescription>): string {
   switch (error.errorType) {
     case SubstitutionErrorType.invalidIDs:
       return 'Ошибка в идентификаторах схем';
@@ -55,7 +57,7 @@ export function describeSubstitutionError(error: ISubstitutionErrorDescription):
 }
 
 /** Retrieves label for {@link IOssItem}. */
-export function labelOssItem(item: IOssItem): string {
+export function labelOssItem(item: RO<IOssItem>): string {
   if (isOperation(item)) {
     return `${(item as IOperation).alias}: ${item.title}`;
   } else {
diff --git a/rsconcept/frontend/src/features/oss/models/oss-api.ts b/rsconcept/frontend/src/features/oss/models/oss-api.ts
index 0f0fac89..80ac64bb 100644
--- a/rsconcept/frontend/src/features/oss/models/oss-api.ts
+++ b/rsconcept/frontend/src/features/oss/models/oss-api.ts
@@ -20,6 +20,7 @@ import {
 } from '@/features/rsform/models/rslang-api';
 
 import { infoMsg } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 
 import { Graph } from '../../../models/graph';
 import { describeSubstitutionError } from '../labels';
@@ -29,17 +30,17 @@ import { type IOperationSchema, type IOssItem, SubstitutionErrorType } from './o
 const STARTING_SUB_INDEX = 900; // max semantic index for starting substitution
 
 /** Checks if element is {@link IOperation} or {@link IBlock}. */
-export function isOperation(item: IOssItem | null): boolean {
+export function isOperation(item: RO<IOssItem> | null): boolean {
   return !!item && 'arguments' in item;
 }
 
 /** Extract contiguous ID of {@link IOperation} or {@link IBlock}. */
-export function getItemID(item: IOssItem): number {
+export function getItemID(item: RO<IOssItem>): number {
   return isOperation(item) ? item.id : -item.id;
 }
 
 /** Sorts library items relevant for the specified {@link IOperationSchema}. */
-export function sortItemsForOSS(oss: IOperationSchema, items: ILibraryItem[]): ILibraryItem[] {
+export function sortItemsForOSS(oss: IOperationSchema, items: readonly ILibraryItem[]): ILibraryItem[] {
   const result = items.filter(item => item.location === oss.location);
   for (const item of items) {
     if (item.visible && item.owner === oss.owner && !result.includes(item)) {
diff --git a/rsconcept/frontend/src/features/rsform/backend/rsform-loader.ts b/rsconcept/frontend/src/features/rsform/backend/rsform-loader.ts
index d0d25c42..4aa22dab 100644
--- a/rsconcept/frontend/src/features/rsform/backend/rsform-loader.ts
+++ b/rsconcept/frontend/src/features/rsform/backend/rsform-loader.ts
@@ -3,6 +3,7 @@
  */
 
 import { Graph } from '@/models/graph';
+import { type RO } from '@/utils/meta';
 
 import { type IConstituenta, type IRSForm, type IRSFormStats } from '../models/rsform';
 import { inferClass, inferStatus, inferTemplate, isBaseSet, isFunctional } from '../models/rsform-api';
@@ -23,7 +24,7 @@ export class RSFormLoader {
   private cstByAlias = new Map<string, IConstituenta>();
   private cstByID = new Map<number, IConstituenta>();
 
-  constructor(input: IRSFormDTO) {
+  constructor(input: RO<IRSFormDTO>) {
     this.schema = structuredClone(input) as IRSForm;
     this.schema.version = input.version ?? 'latest';
   }
diff --git a/rsconcept/frontend/src/features/rsform/dialogs/dlg-create-cst/dlg-create-cst.tsx b/rsconcept/frontend/src/features/rsform/dialogs/dlg-create-cst/dlg-create-cst.tsx
index 2debf6db..3f10c527 100644
--- a/rsconcept/frontend/src/features/rsform/dialogs/dlg-create-cst/dlg-create-cst.tsx
+++ b/rsconcept/frontend/src/features/rsform/dialogs/dlg-create-cst/dlg-create-cst.tsx
@@ -6,6 +6,7 @@ import { zodResolver } from '@hookform/resolvers/zod';
 import { ModalForm } from '@/components/modal';
 import { useDialogsStore } from '@/stores/dialogs';
 import { errorMsg } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 
 import {
   type IConstituentaBasicsDTO,
@@ -21,7 +22,7 @@ import { FormCreateCst } from './form-create-cst';
 export interface DlgCreateCstProps {
   initial: ICreateConstituentaDTO;
   schema: IRSForm;
-  onCreate: (data: IConstituentaBasicsDTO) => void;
+  onCreate: (data: RO<IConstituentaBasicsDTO>) => void;
 }
 
 export function DlgCreateCst() {
diff --git a/rsconcept/frontend/src/features/rsform/dialogs/dlg-cst-template/dlg-cst-template.tsx b/rsconcept/frontend/src/features/rsform/dialogs/dlg-cst-template/dlg-cst-template.tsx
index e77558f3..215f2eed 100644
--- a/rsconcept/frontend/src/features/rsform/dialogs/dlg-cst-template/dlg-cst-template.tsx
+++ b/rsconcept/frontend/src/features/rsform/dialogs/dlg-cst-template/dlg-cst-template.tsx
@@ -10,6 +10,7 @@ import { Loader } from '@/components/loader';
 import { ModalForm } from '@/components/modal';
 import { TabLabel, TabList, TabPanel, Tabs } from '@/components/tabs';
 import { useDialogsStore } from '@/stores/dialogs';
+import { type RO } from '@/utils/meta';
 
 import {
   CstType,
@@ -28,7 +29,7 @@ import { TemplateState } from './template-state';
 
 export interface DlgCstTemplateProps {
   schema: IRSForm;
-  onCreate: (data: IConstituentaBasicsDTO) => void;
+  onCreate: (data: RO<IConstituentaBasicsDTO>) => void;
   insertAfter?: number;
 }
 
diff --git a/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/ast-flow.tsx b/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/ast-flow.tsx
index 903048bb..3de5798a 100644
--- a/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/ast-flow.tsx
+++ b/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/ast-flow.tsx
@@ -4,6 +4,7 @@ import { useEffect } from 'react';
 import { type Edge, MarkerType, type Node, useEdgesState, useNodesState } from 'reactflow';
 
 import { DiagramFlow } from '@/components/flow/diagram-flow';
+import { type RO } from '@/utils/meta';
 
 import { type SyntaxTree } from '../../models/rslang';
 
@@ -22,7 +23,7 @@ const flowOptions = {
 } as const;
 
 interface ASTFlowProps {
-  data: SyntaxTree;
+  data: RO<SyntaxTree>;
   onNodeEnter: (node: Node) => void;
   onNodeLeave: (node: Node) => void;
   onChangeDragging: (value: boolean) => void;
diff --git a/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/dlg-show-ast.tsx b/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/dlg-show-ast.tsx
index d38d6ea1..3a8ea2be 100644
--- a/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/dlg-show-ast.tsx
+++ b/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-ast/dlg-show-ast.tsx
@@ -9,6 +9,7 @@ import { HelpTopic } from '@/features/help';
 
 import { ModalView } from '@/components/modal';
 import { useDialogsStore } from '@/stores/dialogs';
+import { type RO } from '@/utils/meta';
 
 import { type SyntaxTree } from '../../models/rslang';
 
@@ -17,7 +18,7 @@ import { ASTFlow } from './ast-flow';
 const NODE_POPUP_DELAY = 100;
 
 export interface DlgShowASTProps {
-  syntaxTree: SyntaxTree;
+  syntaxTree: RO<SyntaxTree>;
   expression: string;
 }
 
diff --git a/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-type-graph/dlg-show-type-graph.tsx b/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-type-graph/dlg-show-type-graph.tsx
index 1e133863..cf24ae1e 100644
--- a/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-type-graph/dlg-show-type-graph.tsx
+++ b/rsconcept/frontend/src/features/rsform/dialogs/dlg-show-type-graph/dlg-show-type-graph.tsx
@@ -8,6 +8,7 @@ import { HelpTopic } from '@/features/help';
 import { ModalView } from '@/components/modal';
 import { useDialogsStore } from '@/stores/dialogs';
 import { errorMsg } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 
 import { type ITypeInfo } from '../../models/rslang';
 import { TypificationGraph } from '../../models/typification-graph';
@@ -15,7 +16,7 @@ import { TypificationGraph } from '../../models/typification-graph';
 import { MGraphFlow } from './mgraph-flow';
 
 export interface DlgShowTypeGraphProps {
-  items: ITypeInfo[];
+  items: RO<ITypeInfo[]>;
 }
 
 export function DlgShowTypeGraph() {
diff --git a/rsconcept/frontend/src/features/rsform/labels.ts b/rsconcept/frontend/src/features/rsform/labels.ts
index 0cf05db2..1efee02f 100644
--- a/rsconcept/frontend/src/features/rsform/labels.ts
+++ b/rsconcept/frontend/src/features/rsform/labels.ts
@@ -3,6 +3,7 @@
  */
 
 import { PARAMETER } from '@/utils/constants';
+import { type RO } from '@/utils/meta';
 import { prepareTooltip } from '@/utils/utils';
 
 import { type IVersionInfo } from '../library/backend/types';
@@ -18,7 +19,7 @@ import { type GraphColoring } from './stores/term-graph';
 /**
  * Generates description for {@link IConstituenta}.
  */
-export function describeConstituenta(cst: IConstituenta): string {
+export function describeConstituenta(cst: RO<IConstituenta>): string {
   if (cst.cst_type === CstType.STRUCTURED) {
     return (
       cst.term_resolved ||
@@ -43,7 +44,7 @@ export function describeConstituenta(cst: IConstituenta): string {
 /**
  * Generates description for term of a given {@link IConstituenta}.
  */
-export function describeConstituentaTerm(cst: IConstituenta | null): string {
+export function describeConstituentaTerm(cst: RO<IConstituenta> | null): string {
   if (!cst) {
     return '!Конституента отсутствует!';
   }
@@ -57,14 +58,14 @@ export function describeConstituentaTerm(cst: IConstituenta | null): string {
 /**
  * Generates label for {@link IConstituenta}.
  */
-export function labelConstituenta(cst: IConstituenta) {
+export function labelConstituenta(cst: RO<IConstituenta>) {
   return `${cst.alias}: ${describeConstituenta(cst)}`;
 }
 
 /**
  * Generates label for {@link IVersionInfo} of {@link IRSForm}.
  */
-export function labelVersion(value: CurrentVersion, items: IVersionInfo[]) {
+export function labelVersion(value: CurrentVersion, items: RO<IVersionInfo[]>) {
   const version = items.find(ver => ver.id === value);
   return version ? version.version : 'актуальная';
 }
@@ -345,7 +346,7 @@ export function labelTypification({
 }: {
   isValid: boolean;
   resultType: string;
-  args: IArgumentInfo[];
+  args: RO<IArgumentInfo[]>;
 }): string {
   if (!isValid) {
     return 'N/A';
@@ -363,7 +364,7 @@ export function labelTypification({
 /**
  * Generates label for {@link IConstituenta} typification.
  */
-export function labelCstTypification(cst: IConstituenta): string {
+export function labelCstTypification(cst: RO<IConstituenta>): string {
   return labelTypification({
     isValid: cst.parse.status === ParsingStatus.VERIFIED,
     resultType: cst.parse.typification,
@@ -374,7 +375,7 @@ export function labelCstTypification(cst: IConstituenta): string {
 /**
  * Generates label for {@link ISyntaxTreeNode}.
  */
-export function labelSyntaxTree(node: ISyntaxTreeNode): string {
+export function labelSyntaxTree(node: RO<ISyntaxTreeNode>): string {
   // prettier-ignore
   switch (node.typeID) {
     case TokenID.ID_LOCAL:
@@ -531,7 +532,7 @@ export function labelGrammeme(gram: Grammeme): string {
 /**
  * Generates error description for {@link IRSErrorDescription}.
  */
-export function describeRSError(error: IRSErrorDescription): string {
+export function describeRSError(error: RO<IRSErrorDescription>): string {
   // prettier-ignore
   switch (error.errorType) {
     case RSErrorType.unknownSymbol:
diff --git a/rsconcept/frontend/src/features/rsform/models/rsform-api.ts b/rsconcept/frontend/src/features/rsform/models/rsform-api.ts
index c1593b96..7f272988 100644
--- a/rsconcept/frontend/src/features/rsform/models/rsform-api.ts
+++ b/rsconcept/frontend/src/features/rsform/models/rsform-api.ts
@@ -4,6 +4,7 @@
 
 import { BASIC_SCHEMAS, type ILibraryItem } from '@/features/library';
 
+import { type RO } from '@/utils/meta';
 import { TextMatcher } from '@/utils/utils';
 
 import { CstType, ParsingStatus, ValueClass } from '../backend/types';
@@ -18,7 +19,7 @@ import { CATEGORY_CST_TYPE, CstClass, ExpressionStatus, type IConstituenta, type
  * @param query - The query string used for matching.
  * @param mode - The matching mode to determine which properties to include in the matching process.
  */
-export function matchConstituenta(target: IConstituenta, query: string, mode: CstMatchMode): boolean {
+export function matchConstituenta(target: RO<IConstituenta>, query: string, mode: CstMatchMode): boolean {
   const matcher = new TextMatcher(query);
   if ((mode === CstMatchMode.ALL || mode === CstMatchMode.NAME) && matcher.test(target.alias)) {
     return true;
@@ -214,7 +215,7 @@ export function isFunctional(type: CstType): boolean {
 /**
  * Evaluate if {@link IConstituenta} can be used produce structure.
  */
-export function canProduceStructure(cst: IConstituenta): boolean {
+export function canProduceStructure(cst: RO<IConstituenta>): boolean {
   return !!cst.parse.typification && cst.cst_type !== CstType.BASE && cst.cst_type !== CstType.CONSTANT;
 }
 
@@ -271,7 +272,7 @@ export function generateAlias(type: CstType, schema: IRSForm, takenAliases: stri
 /**
  * Sorts library items relevant for InlineSynthesis with specified {@link IRSForm}.
  */
-export function sortItemsForInlineSynthesis(receiver: IRSForm, items: ILibraryItem[]): ILibraryItem[] {
+export function sortItemsForInlineSynthesis(receiver: IRSForm, items: readonly ILibraryItem[]): ILibraryItem[] {
   const result = items.filter(item => item.location === receiver.location);
   for (const item of items) {
     if (item.visible && item.owner === item.owner && !result.includes(item)) {
diff --git a/rsconcept/frontend/src/features/rsform/models/rslang-api.ts b/rsconcept/frontend/src/features/rsform/models/rslang-api.ts
index 00926d75..1e1053f7 100644
--- a/rsconcept/frontend/src/features/rsform/models/rslang-api.ts
+++ b/rsconcept/frontend/src/features/rsform/models/rslang-api.ts
@@ -6,6 +6,7 @@ import { type Tree } from '@lezer/common';
 
 import { cursorNode } from '@/utils/codemirror';
 import { PARAMETER } from '@/utils/constants';
+import { type RO } from '@/utils/meta';
 
 import { CstType, type IRSErrorDescription, type RSErrorType } from '../backend/types';
 import { labelCstTypification } from '../labels';
@@ -36,7 +37,7 @@ export function isSetTypification(text: string): boolean {
 }
 
 /** Infers type of constituent for a given template and arguments. */
-export function inferTemplatedType(templateType: CstType, args: IArgumentValue[]): CstType {
+export function inferTemplatedType(templateType: CstType, args: RO<IArgumentValue[]>): CstType {
   if (args.length === 0 || args.some(arg => !arg.value)) {
     return templateType;
   } else if (templateType === CstType.PREDICATE) {
@@ -92,7 +93,7 @@ export function splitTemplateDefinition(target: string) {
  * It replaces template argument placeholders in the expression with their corresponding values
  * from the provided arguments.
  */
-export function substituteTemplateArgs(expression: string, args: IArgumentValue[]): string {
+export function substituteTemplateArgs(expression: string, args: RO<IArgumentValue[]>): string {
   if (args.every(arg => !arg.value)) {
     return expression;
   }
@@ -121,7 +122,7 @@ export function substituteTemplateArgs(expression: string, args: IArgumentValue[
 /**
  * Generate ErrorID label.
  */
-export function getRSErrorPrefix(error: IRSErrorDescription): string {
+export function getRSErrorPrefix(error: RO<IRSErrorDescription>): string {
   const id = error.errorType.toString(16);
   // prettier-ignore
   switch(inferErrorClass(error.errorType)) {
@@ -133,12 +134,12 @@ export function getRSErrorPrefix(error: IRSErrorDescription): string {
 }
 
 /** Apply alias mapping. */
-export function applyAliasMapping(target: string, mapping: AliasMapping): string {
+export function applyAliasMapping(target: string, mapping: RO<AliasMapping>): string {
   return applyPattern(target, mapping, GLOBALS_REGEXP);
 }
 
 /** Apply alias typification mapping. */
-export function applyTypificationMapping(target: string, mapping: AliasMapping): string {
+export function applyTypificationMapping(target: string, mapping: RO<AliasMapping>): string {
   const modified = applyAliasMapping(target, mapping);
   if (modified === target) {
     return target;
diff --git a/rsconcept/frontend/src/features/rsform/models/typification-graph.ts b/rsconcept/frontend/src/features/rsform/models/typification-graph.ts
index 70c3e0e5..a611efd0 100644
--- a/rsconcept/frontend/src/features/rsform/models/typification-graph.ts
+++ b/rsconcept/frontend/src/features/rsform/models/typification-graph.ts
@@ -3,6 +3,7 @@
  */
 
 import { PARAMETER } from '@/utils/constants';
+import { type RO } from '@/utils/meta';
 
 import { type IArgumentInfo } from './rslang';
 
@@ -35,7 +36,7 @@ export class TypificationGraph {
    * @param result - typification of the formal definition.
    * @param args - arguments for term or predicate function.
    */
-  addConstituenta(alias: string, result: string, args: IArgumentInfo[]): void {
+  addConstituenta(alias: string, result: string, args: RO<IArgumentInfo[]>): void {
     const argsNode = this.processArguments(args);
     const resultNode = this.processResult(result);
     const combinedNode = this.combineResults(resultNode, argsNode);
@@ -122,7 +123,7 @@ export class TypificationGraph {
     this.nodeByAlias.set(alias, nodeToAnnotate);
   }
 
-  private processArguments(args: IArgumentInfo[]): TypificationGraphNode | null {
+  private processArguments(args: RO<IArgumentInfo[]>): TypificationGraphNode | null {
     if (args.length === 0) {
       return null;
     }
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-constituenta/form-constituenta.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-constituenta/form-constituenta.tsx
index a7fc4a47..52704d9b 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-constituenta/form-constituenta.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-constituenta/form-constituenta.tsx
@@ -13,6 +13,7 @@ import { Indicator } from '@/components/view';
 import { useDialogsStore } from '@/stores/dialogs';
 import { useModificationStore } from '@/stores/modification';
 import { errorMsg, tooltipText } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 import { promptUnsaved } from '@/utils/utils';
 
 import {
@@ -68,7 +69,7 @@ export function FormConstituenta({ disabled, id, toggleReset, schema, activeCst,
     }
   });
   const [forceComment, setForceComment] = useState(false);
-  const [localParse, setLocalParse] = useState<IExpressionParseDTO | null>(null);
+  const [localParse, setLocalParse] = useState<RO<IExpressionParseDTO> | null>(null);
 
   const typification = useMemo(
     () =>
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/editor-rsexpression.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/editor-rsexpression.tsx
index 9b267eaf..3b2acaf7 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/editor-rsexpression.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/editor-rsexpression.tsx
@@ -8,6 +8,7 @@ import { useResetOnChange } from '@/hooks/use-reset-on-change';
 import { useDialogsStore } from '@/stores/dialogs';
 import { usePreferencesStore } from '@/stores/preferences';
 import { errorMsg } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 
 import {
   type ICheckConstituentaDTO,
@@ -42,7 +43,7 @@ interface EditorRSExpressionProps {
   disabled?: boolean;
   toggleReset?: boolean;
 
-  onChangeLocalParse: (typification: IExpressionParseDTO) => void;
+  onChangeLocalParse: (typification: RO<IExpressionParseDTO>) => void;
   onOpenEdit: (cstID: number) => void;
   onShowTypeGraph: (event: React.MouseEvent<Element>) => void;
 }
@@ -62,7 +63,7 @@ export function EditorRSExpression({
 
   const [isModified, setIsModified] = useState(false);
   const rsInput = useRef<ReactCodeMirrorRef>(null);
-  const [parseData, setParseData] = useState<IExpressionParseDTO | null>(null);
+  const [parseData, setParseData] = useState<RO<IExpressionParseDTO> | null>(null);
 
   const isProcessing = useMutatingRSForm();
   const showControls = usePreferencesStore(state => state.showExpressionControls);
@@ -78,7 +79,7 @@ export function EditorRSExpression({
   function checkConstituenta(
     expression: string,
     activeCst: IConstituenta,
-    onSuccess?: (data: IExpressionParseDTO) => void
+    onSuccess?: (data: RO<IExpressionParseDTO>) => void
   ) {
     const data: ICheckConstituentaDTO = {
       definition_formal: expression,
@@ -96,7 +97,7 @@ export function EditorRSExpression({
     setIsModified(newValue !== activeCst.definition_formal);
   }
 
-  function handleCheckExpression(callback?: (parse: IExpressionParseDTO) => void) {
+  function handleCheckExpression(callback?: (parse: RO<IExpressionParseDTO>) => void) {
     checkConstituenta(value, activeCst, parse => {
       onChangeLocalParse(parse);
       if (parse.errors.length > 0) {
@@ -109,7 +110,7 @@ export function EditorRSExpression({
     });
   }
 
-  function onShowError(error: IRSErrorDescription, prefixLen: number) {
+  function onShowError(error: RO<IRSErrorDescription>, prefixLen: number) {
     if (!rsInput.current) {
       return;
     }
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/parsing-result.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/parsing-result.tsx
index fae76f79..cbc061e4 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/parsing-result.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/parsing-result.tsx
@@ -1,14 +1,16 @@
 import clsx from 'clsx';
 
+import { type RO } from '@/utils/meta';
+
 import { type IExpressionParseDTO, type IRSErrorDescription } from '../../../backend/types';
 import { describeRSError } from '../../../labels';
 import { getRSErrorPrefix } from '../../../models/rslang-api';
 
 interface ParsingResultProps {
-  data: IExpressionParseDTO | null;
+  data: RO<IExpressionParseDTO> | null;
   disabled?: boolean;
   isOpen: boolean;
-  onShowError: (error: IRSErrorDescription) => void;
+  onShowError: (error: RO<IRSErrorDescription>) => void;
 }
 
 export function ParsingResult({ isOpen, data, disabled, onShowError }: ParsingResultProps) {
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/status-bar.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/status-bar.tsx
index 51bf981c..1fcd99c7 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/status-bar.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-rsexpression/status-bar.tsx
@@ -8,6 +8,7 @@ import { BadgeHelp } from '@/features/help/components';
 import { Loader } from '@/components/loader';
 import { APP_COLORS } from '@/styling/colors';
 import { globalIDs } from '@/utils/constants';
+import { type RO } from '@/utils/meta';
 import { prepareTooltip } from '@/utils/utils';
 
 import { type IExpressionParseDTO, ParsingStatus } from '../../../backend/types';
@@ -21,7 +22,7 @@ interface StatusBarProps {
   className?: string;
   processing: boolean;
   isModified: boolean;
-  parseData: IExpressionParseDTO | null;
+  parseData: RO<IExpressionParseDTO> | null;
   activeCst: IConstituenta;
   onAnalyze: () => void;
 }
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-edit-schema.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-edit-schema.tsx
index 85c564ca..d251f65d 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-edit-schema.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-edit-schema.tsx
@@ -81,7 +81,7 @@ export function MenuEditSchema() {
       cstID: targetCst.id
     }).then(cstList => {
       if (cstList.length !== 0) {
-        setSelected(cstList);
+        setSelected([...cstList]);
       }
     });
   }
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-main.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-main.tsx
index 94bc99be..4565ef49 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-main.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/menu-main.tsx
@@ -26,6 +26,7 @@ import { useDialogsStore } from '@/stores/dialogs';
 import { useModificationStore } from '@/stores/modification';
 import { EXTEOR_TRS_FILE } from '@/utils/constants';
 import { infoMsg, tooltipText } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 import { generatePageQR, promptUnsaved, sharePage } from '@/utils/utils';
 
 import { useDownloadRSForm } from '../../backend/use-download-rsform';
@@ -78,9 +79,9 @@ export function MenuMain() {
     void download({
       itemID: schema.id,
       version: schema.version === 'latest' ? undefined : schema.version
-    }).then((data: Blob) => {
+    }).then((data: RO<Blob>) => {
       try {
-        fileDownload(data, fileName);
+        fileDownload(data as Blob, fileName);
       } catch (error) {
         console.error(error);
       }
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/rsedit-state.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/rsedit-state.tsx
index c79adabb..96bc954d 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/rsedit-state.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/rsedit-state.tsx
@@ -14,6 +14,7 @@ import { useModificationStore } from '@/stores/modification';
 import { usePreferencesStore } from '@/stores/preferences';
 import { PARAMETER, prefixes } from '@/utils/constants';
 import { promptText } from '@/utils/labels';
+import { type RO } from '@/utils/meta';
 import { promptUnsaved } from '@/utils/utils';
 
 import { CstType, type IConstituentaBasicsDTO, type ICreateConstituentaDTO } from '../../backend/types';
@@ -136,7 +137,7 @@ export const RSEditState = ({
     });
   }
 
-  function onCreateCst(newCst: IConstituentaBasicsDTO) {
+  function onCreateCst(newCst: RO<IConstituentaBasicsDTO>) {
     setSelected([newCst.id]);
     navigateRSForm({ tab: activeTab, activeID: newCst.id });
     if (activeTab === RSTabID.CST_LIST) {
diff --git a/rsconcept/frontend/src/utils/meta.ts b/rsconcept/frontend/src/utils/meta.ts
new file mode 100644
index 00000000..50439a10
--- /dev/null
+++ b/rsconcept/frontend/src/utils/meta.ts
@@ -0,0 +1,83 @@
+/**
+ * Module: Generic high order utility functions.
+ */
+
+// List of disallowed object types (non-plain)
+// ALLOW: Date | RegExp | ArrayBuffer | DataView
+type DisallowedObjects =
+  | Map<unknown, unknown>
+  | Set<unknown>
+  | WeakMap<object, unknown>
+  | WeakSet<object>
+  | Promise<unknown>;
+
+// Detects any disallowed object type directly
+type IsDisallowedObject<T> = T extends DisallowedObjects ? true : false;
+
+// Detects if any property in T is a function
+type HasFunctionProps<T> = {
+  [K in keyof T]: T[K] extends (...args: unknown[]) => unknown ? true : false;
+}[keyof T] extends true
+  ? true
+  : false;
+
+// Detects if any property in T is a disallowed object
+type HasDisallowedProps<T> = {
+  [K in keyof T]: IsDisallowedObject<T[K]>;
+}[keyof T] extends true
+  ? true
+  : false;
+
+// Detects if T is a class instance (has constructor)
+type IsClassInstance<T> = T extends object
+  ? T extends { constructor: new (...args: unknown[]) => unknown }
+    ? true
+    : false
+  : false;
+
+// The final check — should the object be rejected?
+type IsInvalid<T> = T extends object
+  ? HasFunctionProps<T> extends true
+    ? true
+    : HasDisallowedProps<T> extends true
+    ? true
+    : IsClassInstance<T> extends true
+    ? true
+    : false
+  : false;
+
+/**
+ * Apply readonly modifier to all properties of a SIMPLE object recursively.
+ * only works for arrays, dictionaries and primitives.
+ */
+export type RO<T> = IsInvalid<T> extends true
+  ? never
+  : T extends readonly unknown[]
+  ? readonly RO<T[number]>[]
+  : T extends object
+  ? { readonly [K in keyof T]: RO<T[K]> }
+  : T;
+
+/**
+ * Freeze an object.
+ */
+export function deepFreeze<T>(obj: T): RO<T> {
+  // Ensure the input object is not null or undefined
+  if (obj === null || obj === undefined) {
+    throw new Error('Cannot freeze null or undefined');
+  }
+
+  // Freeze the current object
+  Object.freeze(obj);
+
+  // Freeze properties recursively
+  Object.getOwnPropertyNames(obj).forEach(prop => {
+    const value = (obj as Record<string, unknown>)[prop];
+    if (value !== null && typeof value === 'object' && !Object.isFrozen(value)) {
+      deepFreeze(value);
+    }
+  });
+
+  // Return the frozen object
+  return obj as RO<T>;
+}
diff --git a/rsconcept/frontend/src/utils/utils.ts b/rsconcept/frontend/src/utils/utils.ts
index f73da02c..e0271407 100644
--- a/rsconcept/frontend/src/utils/utils.ts
+++ b/rsconcept/frontend/src/utils/utils.ts
@@ -128,7 +128,7 @@ export function extractErrorMessage(error: Error | AxiosError): string {
 /**
  * Convert array of objects to CSV Blob.
  */
-export function convertToCSV(targetObj: object[]): Blob {
+export function convertToCSV(targetObj: readonly object[]): Blob {
   if (!targetObj || targetObj.length === 0) {
     return new Blob([], { type: 'text/csv;charset=utf-8;' });
   }