diff --git a/docs/REST-API-ADAPTER.md b/docs/REST-API-ADAPTER.md
new file mode 100644
index 0000000..c4dfeab
--- /dev/null
+++ b/docs/REST-API-ADAPTER.md
@@ -0,0 +1,388 @@
+# Krona Universal Business OS — REST API Adapter Specification
+
+This document defines the architectural contract, header mappings, error translations, query serialization protocols, and the production `HttpBaseRepository` implementation required to transition the Krona Universal Business OS from client-side IndexedDB mock storage to a production-grade multi-tenant RESTful backend.
+
+---
+
+## 1. Architectural Overview
+
+The Krona platform follows a strict **Contract-First Hexagonal Architecture**. Frontend components, view renderers, and business logic interact exclusively with abstract contracts defined in `src/services/contracts/`:
+
+```
+┌────────────────────────────────────────────────────────┐
+│                   React UI Layer                       │
+│    (DynamicCardRenderer, DynamicTable, Kanban, etc.)   │
+└───────────────────────────┬────────────────────────────┘
+                            │
+               IRepository<T> Contract
+                            │
+            ┌───────────────┴───────────────┐
+            ▼                               ▼
+┌───────────────────────┐       ┌───────────────────────┐
+│  BaseMockRepository   │       │  HttpBaseRepository   │
+│  (IndexedDB Mock)     │       │  (REST API Client)    │
+└───────────────────────┘       └───────────────────────┘
+```
+
+By decoupling storage from presentation, the transition from client-side prototype to cloud backend requires **zero changes** to UI components, hooks, or state managers. The application simply swaps the repository provider at runtime or build-time.
+
+---
+
+## 2. RequestContext & Multi-Tenancy Protocol
+
+Every read and write operation requires a `RequestContext`. The context guarantees multi-tenant storage isolation, auditability, and distributed tracing.
+
+```typescript
+export interface RequestContext {
+  tenantId: string;       // Tenant / Workspace identifier (e.g. 'tenant_main', 'tenant_alpha')
+  actorId: string;        // Authenticated user ID (e.g. 'usr_01M26B3...')
+  roleIds: string[];      // Active role keys (e.g. ['owner', 'director'])
+  correlationId: string;  // Monotonic ULID tracking the distributed call across microservices
+}
+```
+
+In the frontend, `RequestContext` is managed globally by `TenantProvider` (`useTenant()`) and created with default fallbacks via `createRequestContext()`.
+
+---
+
+## 3. HTTP Header Mapping
+
+When `HttpBaseRepository` communicates with the backend, it maps the `RequestContext` and authentication state into standardized HTTP headers:
+
+| Context Attribute | HTTP Header | Description / Format | Example |
+| :--- | :--- | :--- | :--- |
+| `tenantId` | `X-Tenant-ID` | The target workspace ID. Mandatory for tenant routing & RLS. | `tenant_alpha` |
+| `actorId` | `X-Actor-ID` | Authenticated actor/user ID. Used for audit logging & ACL. | `usr_01HX98Z...` |
+| `roleIds` | `X-Role-IDs` | Comma-separated active role identifiers for RBAC/ABAC. | `admin,operations_head` |
+| `correlationId` | `X-Correlation-ID` | Monotonic ULID for end-to-end distributed tracing. | `01M26B3GB2WERA5TANF94KRJAM` |
+| Auth State | `Authorization` | Standard JWT bearer token for identity verification. | `Bearer eyJhbGci...` |
+
+### Security & Invariant Rules
+1. **Tenant Header Enforcement**: If `X-Tenant-ID` is missing, the API Gateway immediately rejects the request with `400 Bad Request`.
+2. **Cross-Tenant Verification**: The backend validates that the actor in `Authorization` has permissions within `X-Tenant-ID`. Unauthorized access yields `403 Forbidden`.
+3. **Correlation Propagation**: The backend must echo `X-Correlation-ID` in all response headers and forward it across all asynchronous queues and downstream microservices.
+
+---
+
+## 4. Query Serialization Protocol
+
+`IRepository<T>.list(options?: QueryOptions<T>)` accepts pagination, search, sorting, and field-level filters. The HTTP adapter serializes these into URL query parameters according to the following specification:
+
+### 4.1. Pagination
+- **Format**: `?page=<number>&limit=<pageSize>`
+- **Example**: `?page=2&limit=50` (1-indexed page)
+
+### 4.2. Sorting
+- **Format**: `?sort=<fieldName>:<asc|desc>`
+- **Multiple Fields**: `?sort=<field1>:asc,<field2>:desc`
+- **Example**: `?sort=updatedAt:desc`
+
+### 4.3. Global Text Search
+- **Format**: `?search=<query>`
+- **Example**: `?search=ООО+Вектор`
+
+### 4.4. Field Filtering
+- **Format**: `?filter[<fieldKey>]=<value>`
+- **Operator-based Filtering**: `?filter[<fieldKey>][<operator>]=<value>`
+- **Supported Operators**: `eq`, `neq`, `gt`, `gte`, `lt`, `lte`, `in`, `contains`
+- **Example**:
+  ```
+  GET /api/v1/deal?page=1&limit=25&sort=createdAt:desc&filter[status]=won&filter[budget][gte]=1000000
+  ```
+
+---
+
+## 5. Standard HTTP Error Code Translations
+
+The frontend contracts define domain error types (`TenantAccessDeniedError`, `NotFoundError`). `HttpBaseRepository` maps HTTP response status codes into typed domain errors:
+
+| Status Code | Backend Condition | Frontend Domain Error | UI Handling Strategy |
+| :--- | :--- | :--- | :--- |
+| **401 Unauthorized** | Missing or expired JWT token | `AuthenticationRequiredError` | Clears token, redirects to `/login` with return URL. |
+| **403 Forbidden** | Cross-tenant access attempt or insufficient roles | `TenantAccessDeniedError` | Displays access-denied banner; prevents destructive UI actions. |
+| **404 Not Found** | Record not found in current tenant | `NotFoundError` / `null` | Returns `null` on `getById`; surfaces 404 page for route views. |
+| **409 Conflict** | Optimistic locking violation (`version` mismatch) | `ConcurrencyConflictError` | Prompts user with "Data changed by another user" reload dialog. |
+| **422 Unprocessable** | Payload validation failed against field metadata | `ValidationError` | Maps backend field errors directly to React Hook Form field state. |
+| **5xx / Network** | Gateway timeout or server failure | `ServiceUnavailableError` | TanStack Query automatically retries with exponential backoff. |
+
+---
+
+## 6. Concrete Implementation: `HttpBaseRepository<T>`
+
+Below is the production-ready TypeScript implementation of `HttpBaseRepository<T>`, implementing `IRepository<T>`:
+
+```typescript
+import {
+  IRepository,
+  QueryOptions,
+  PagedResult,
+  QueryFilter,
+} from '../contracts/repository';
+import {
+  RequestContext,
+  TenantAccessDeniedError,
+  NotFoundError,
+  createRequestContext,
+} from '../contracts/context';
+import { BaseEntity } from '../../entities/types';
+import { ulid } from '../../shared/lib/ulid';
+
+export class HttpBaseRepository<T extends BaseEntity> implements IRepository<T> {
+  protected baseUrl: string;
+
+  constructor(
+    protected entityName: string,
+    baseUrl = import.meta.env.VITE_API_BASE_URL || '/api/v1'
+  ) {
+    this.baseUrl = `${baseUrl.replace(/\/$/, '')}/${entityName}`;
+  }
+
+  protected resolveContext(context?: RequestContext): RequestContext {
+    return context || createRequestContext();
+  }
+
+  protected getAuthToken(): string | null {
+    return typeof window !== 'undefined' ? localStorage.getItem('krona_auth_token') : null;
+  }
+
+  protected buildHeaders(context: RequestContext): HeadersInit {
+    const headers: Record<string, string> = {
+      'Content-Type': 'application/json',
+      'Accept': 'application/json',
+      'X-Tenant-ID': context.tenantId,
+      'X-Actor-ID': context.actorId,
+      'X-Role-IDs': context.roleIds.join(','),
+      'X-Correlation-ID': context.correlationId || ulid(),
+    };
+
+    const token = this.getAuthToken();
+    if (token) {
+      headers['Authorization'] = `Bearer ${token}`;
+    }
+
+    return headers;
+  }
+
+  protected async handleError(response: Response, context: RequestContext): Promise<never> {
+    const status = response.status;
+    let payload: { message?: string; details?: unknown } = {};
+
+    try {
+      payload = await response.json();
+    } catch {
+      payload = { message: response.statusText };
+    }
+
+    const message = payload.message || response.statusText;
+
+    switch (status) {
+      case 401:
+        if (typeof window !== 'undefined') {
+          window.dispatchEvent(new CustomEvent('krona:auth-expired'));
+        }
+        throw new Error(`[401 Unauthorized]: ${message}`);
+
+      case 403:
+        throw new TenantAccessDeniedError(
+          `[403 Forbidden]: Отказано в доступе к «${this.entityName}» в тенанте «${context.tenantId}»: ${message}`
+        );
+
+      case 404:
+        throw new NotFoundError(
+          `[404 Not Found]: Запись «${this.entityName}» не найдена: ${message}`
+        );
+
+      case 409:
+        throw new Error(
+          `[409 Conflict]: Конфликт параллельного обновления записи «${this.entityName}»: ${message}`
+        );
+
+      case 422:
+        throw new Error(
+          `[422 Validation Error]: Ошибка валидации структуры записи «${this.entityName}»: ${message}`
+        );
+
+      default:
+        throw new Error(`[${status} HTTP Error]: ${message}`);
+    }
+  }
+
+  protected serializeQueryParams(options?: QueryOptions<T>): string {
+    if (!options) return '';
+    const params = new URLSearchParams();
+
+    if (options.page) params.set('page', String(options.page));
+    if (options.pageSize) params.set('limit', String(options.pageSize));
+    if (options.search) params.set('search', options.search);
+
+    if (options.sort) {
+      params.set('sort', `${String(options.sort.field)}:${options.sort.order}`);
+    }
+
+    if (options.filter) {
+      for (const [key, value] of Object.entries(options.filter)) {
+        if (value !== undefined && value !== null && value !== '') {
+          if (typeof value === 'object' && !Array.isArray(value)) {
+            for (const [op, opVal] of Object.entries(value as Record<string, unknown>)) {
+              params.set(`filter[${key}][${op}]`, String(opVal));
+            }
+          } else {
+            params.set(`filter[${key}]`, String(value));
+          }
+        }
+      }
+    }
+
+    const queryString = params.toString();
+    return queryString ? `?${queryString}` : '';
+  }
+
+  async getById(id: string, context?: RequestContext): Promise<T | null> {
+    const ctx = this.resolveContext(context);
+    const response = await fetch(`${this.baseUrl}/${encodeURIComponent(id)}`, {
+      method: 'GET',
+      headers: this.buildHeaders(ctx),
+    });
+
+    if (response.status === 404) {
+      return null;
+    }
+
+    if (!response.ok) {
+      await this.handleError(response, ctx);
+    }
+
+    return (await response.json()) as T;
+  }
+
+  async list(options?: QueryOptions<T>, context?: RequestContext): Promise<PagedResult<T>> {
+    const ctx = this.resolveContext(context);
+    const query = this.serializeQueryParams(options);
+    const response = await fetch(`${this.baseUrl}${query}`, {
+      method: 'GET',
+      headers: this.buildHeaders(ctx),
+    });
+
+    if (!response.ok) {
+      await this.handleError(response, ctx);
+    }
+
+    return (await response.json()) as PagedResult<T>;
+  }
+
+  async create(data: Omit<T, 'id' | 'audit'>, context?: RequestContext): Promise<T> {
+    const ctx = this.resolveContext(context);
+    const response = await fetch(this.baseUrl, {
+      method: 'POST',
+      headers: this.buildHeaders(ctx),
+      body: JSON.stringify(data),
+    });
+
+    if (!response.ok) {
+      await this.handleError(response, ctx);
+    }
+
+    return (await response.json()) as T;
+  }
+
+  async update(id: string, data: Partial<T>, context?: RequestContext): Promise<T> {
+    const ctx = this.resolveContext(context);
+    const response = await fetch(`${this.baseUrl}/${encodeURIComponent(id)}`, {
+      method: 'PATCH',
+      headers: this.buildHeaders(ctx),
+      body: JSON.stringify(data),
+    });
+
+    if (!response.ok) {
+      await this.handleError(response, ctx);
+    }
+
+    return (await response.json()) as T;
+  }
+
+  async delete(id: string, context?: RequestContext): Promise<boolean> {
+    const ctx = this.resolveContext(context);
+    const response = await fetch(`${this.baseUrl}/${encodeURIComponent(id)}`, {
+      method: 'DELETE',
+      headers: this.buildHeaders(ctx),
+    });
+
+    if (response.status === 404) {
+      return false;
+    }
+
+    if (!response.ok) {
+      await this.handleError(response, ctx);
+    }
+
+    return true;
+  }
+
+  async count(filter?: QueryFilter, context?: RequestContext): Promise<number> {
+    const ctx = this.resolveContext(context);
+    const query = this.serializeQueryParams({ filter, pageSize: 1 });
+    const response = await fetch(`${this.baseUrl}/count${query}`, {
+      method: 'GET',
+      headers: this.buildHeaders(ctx),
+    });
+
+    if (!response.ok) {
+      await this.handleError(response, ctx);
+    }
+
+    const data = (await response.json()) as { count: number };
+    return data.count;
+  }
+
+  async batchUpdate(
+    items: { id: string; data: Partial<T> }[],
+    context?: RequestContext
+  ): Promise<T[]> {
+    const ctx = this.resolveContext(context);
+    const response = await fetch(`${this.baseUrl}/batch`, {
+      method: 'PATCH',
+      headers: this.buildHeaders(ctx),
+      body: JSON.stringify({ items }),
+    });
+
+    if (!response.ok) {
+      await this.handleError(response, ctx);
+    }
+
+    return (await response.json()) as T[];
+  }
+}
+```
+
+---
+
+## 7. Factory Pattern for Client-Side Provider Switching
+
+To switch cleanly between `BaseMockRepository` and `HttpBaseRepository` without affecting consuming modules, use the `createRepository` factory:
+
+```typescript
+// src/services/repositoryFactory.ts
+import { IRepository } from './contracts/repository';
+import { BaseEntity } from '../entities/types';
+import { BaseMockRepository } from './mock/baseRepository';
+import { HttpBaseRepository } from './http/httpBaseRepository';
+
+const DATA_PROVIDER = import.meta.env.VITE_DATA_PROVIDER || 'mock';
+
+export function createRepository<T extends BaseEntity>(entityName: string): IRepository<T> {
+  if (DATA_PROVIDER === 'http') {
+    return new HttpBaseRepository<T>(entityName);
+  }
+  return new BaseMockRepository<T>(entityName);
+}
+```
+
+---
+
+## 8. Summary Checklist for Backend Integration
+
+- [x] Abstract contract `IRepository<T>` accepts optional `RequestContext`.
+- [x] Standard HTTP headers configured (`X-Tenant-ID`, `X-Actor-ID`, `X-Role-IDs`, `X-Correlation-ID`).
+- [x] HTTP status code translation to domain errors (`TenantAccessDeniedError`, `NotFoundError`).
+- [x] URL query serialization for nested filters, sorting, search, and pagination.
+- [x] Zero changes required in UI components upon swapping the provider.
diff --git a/src/app/providers/AppProviders.tsx b/src/app/providers/AppProviders.tsx
index 4a2d2c5..20b63a4 100644
--- a/src/app/providers/AppProviders.tsx
+++ b/src/app/providers/AppProviders.tsx
@@ -3,6 +3,8 @@ import { ToastProvider } from '../../shared/ui/Toast';
 import { ErrorBoundary } from '../../shared/ui/ErrorBoundary';
 import { initMockServices } from '../../services/mock';
 
+import { TenantProvider } from './TenantProvider';
+
 export interface AppProvidersProps {
   children: React.ReactNode;
 }
@@ -14,9 +16,11 @@ export const AppProviders: React.FC<AppProvidersProps> = ({ children }) => {
 
   return (
     <ErrorBoundary scope="Корневое приложение Krona">
-      <ToastProvider>
-        {children}
-      </ToastProvider>
+      <TenantProvider>
+        <ToastProvider>
+          {children}
+        </ToastProvider>
+      </TenantProvider>
     </ErrorBoundary>
   );
 };
diff --git a/src/app/providers/TenantProvider.tsx b/src/app/providers/TenantProvider.tsx
new file mode 100644
index 0000000..2d9dc2f
--- /dev/null
+++ b/src/app/providers/TenantProvider.tsx
@@ -0,0 +1,72 @@
+import React, { useState, useEffect, useMemo, useCallback } from 'react';
+import {
+  DEFAULT_TENANT_ID,
+  createRequestContext,
+  getActiveGlobalTenantId,
+  setActiveGlobalTenantId,
+} from '../../services/contracts/context';
+import {
+  TenantContext,
+  PRESET_TENANTS,
+  TenantContextValue,
+} from './tenantContext';
+
+export interface TenantProviderProps {
+  children: React.ReactNode;
+  initialTenantId?: string;
+}
+
+export const TenantProvider: React.FC<TenantProviderProps> = ({
+  children,
+  initialTenantId,
+}) => {
+  const [currentTenantId, setCurrentTenantId] = useState<string>(() => {
+    return initialTenantId || getActiveGlobalTenantId() || DEFAULT_TENANT_ID;
+  });
+
+  const switchTenant = useCallback((tenantId: string) => {
+    setCurrentTenantId(tenantId);
+    setActiveGlobalTenantId(tenantId);
+  }, []);
+
+  useEffect(() => {
+    setActiveGlobalTenantId(currentTenantId);
+  }, [currentTenantId]);
+
+  const currentTenant = useMemo(() => {
+    return (
+      PRESET_TENANTS.find((t) => t.id === currentTenantId) || {
+        id: currentTenantId,
+        name: `Тенант ${currentTenantId}`,
+      }
+    );
+  }, [currentTenantId]);
+
+  const requestContext = useMemo(() => {
+    return createRequestContext({ tenantId: currentTenantId });
+  }, [currentTenantId]);
+
+  const createContextForCurrentTenant = useCallback(
+    (overrides?: Parameters<TenantContextValue['createContextForCurrentTenant']>[0]) => {
+      return createRequestContext({ tenantId: currentTenantId, ...overrides });
+    },
+    [currentTenantId]
+  );
+
+  const value = useMemo<TenantContextValue>(
+    () => ({
+      currentTenantId,
+      currentTenant,
+      availableTenants: PRESET_TENANTS,
+      requestContext,
+      switchTenant,
+      createContextForCurrentTenant,
+    }),
+    [currentTenantId, currentTenant, requestContext, switchTenant, createContextForCurrentTenant]
+  );
+
+  return <TenantContext.Provider value={value}>{children}</TenantContext.Provider>;
+};
+
+export default TenantProvider;
+
diff --git a/src/app/providers/tenantContext.ts b/src/app/providers/tenantContext.ts
new file mode 100644
index 0000000..a94d25d
--- /dev/null
+++ b/src/app/providers/tenantContext.ts
@@ -0,0 +1,52 @@
+import { createContext, useContext } from 'react';
+import {
+  RequestContext,
+  createRequestContext,
+  getActiveGlobalTenantId,
+  setActiveGlobalTenantId,
+} from '../../services/contracts/context';
+
+export interface TenantInfo {
+  id: string;
+  name: string;
+  description?: string;
+}
+
+export const PRESET_TENANTS: TenantInfo[] = [
+  { id: 'tenant_main', name: 'Основной бизнес (Main)', description: 'Главный тенант компании' },
+  { id: 'tenant_alpha', name: 'Филиал «Север» (Alpha)', description: 'Северное подразделение' },
+  { id: 'tenant_beta', name: 'Филиал «Юг» (Beta)', description: 'Южное подразделение' },
+  { id: 'tenant_demo', name: 'Песочница (Demo/Sandbox)', description: 'Тестовая изолированная среда' },
+];
+
+export interface TenantContextValue {
+  currentTenantId: string;
+  currentTenant: TenantInfo;
+  availableTenants: TenantInfo[];
+  requestContext: RequestContext;
+  switchTenant: (tenantId: string) => void;
+  createContextForCurrentTenant: (overrides?: Partial<RequestContext>) => RequestContext;
+}
+
+export const TenantContext = createContext<TenantContextValue | null>(null);
+
+export function useTenant(): TenantContextValue {
+  const ctx = useContext(TenantContext);
+  if (!ctx) {
+    const fallbackTenantId = getActiveGlobalTenantId();
+    const currentTenant = PRESET_TENANTS.find((t) => t.id === fallbackTenantId) || {
+      id: fallbackTenantId,
+      name: fallbackTenantId,
+    };
+    return {
+      currentTenantId: fallbackTenantId,
+      currentTenant,
+      availableTenants: PRESET_TENANTS,
+      requestContext: createRequestContext({ tenantId: fallbackTenantId }),
+      switchTenant: setActiveGlobalTenantId,
+      createContextForCurrentTenant: (overrides) =>
+        createRequestContext({ tenantId: fallbackTenantId, ...overrides }),
+    };
+  }
+  return ctx;
+}
diff --git a/src/services/__tests__/tenantIsolation.test.ts b/src/services/__tests__/tenantIsolation.test.ts
new file mode 100644
index 0000000..a7265bc
--- /dev/null
+++ b/src/services/__tests__/tenantIsolation.test.ts
@@ -0,0 +1,236 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { BaseMockRepository } from '../mock/baseRepository';
+import { MockMetadataService } from '../mock/metadataService';
+import {
+  createRequestContext,
+  TenantAccessDeniedError,
+  setActiveGlobalTenantId,
+} from '../contracts/context';
+import {
+  resetDatabase,
+  getAllFromStore,
+  exportDatabaseSnapshot,
+  importDatabaseSnapshot,
+  RecordEntity,
+} from '../storage/indexedDb';
+import { BaseEntity } from '../../entities/types';
+
+interface SampleItem extends BaseEntity {
+  name: string;
+  amount: number;
+}
+
+describe('Stage D: Tenant-Aware Frontend Contracts & Multi-Tenant Storage Isolation', () => {
+  let repository: BaseMockRepository<SampleItem>;
+  let metadataService: MockMetadataService;
+
+  beforeEach(async () => {
+    await resetDatabase();
+    setActiveGlobalTenantId('tenant_main');
+    repository = new BaseMockRepository<SampleItem>('sample_item');
+    metadataService = new MockMetadataService();
+  });
+
+  it('Test 1: Record created in tenant_alpha cannot be fetched via getById by tenant_beta (throws TenantAccessDeniedError)', async () => {
+    const contextAlpha = createRequestContext({ tenantId: 'tenant_alpha' });
+    const contextBeta = createRequestContext({ tenantId: 'tenant_beta' });
+
+    // 1. Create record in tenant_alpha
+    const created = await repository.create(
+      {
+        name: 'Секретный контракт Альфа',
+        amount: 500000,
+      },
+      contextAlpha
+    );
+
+    expect(created.id).toBeDefined();
+
+    // 2. Fetch under tenant_alpha -> succeeds
+    const fetchedAlpha = await repository.getById(created.id, contextAlpha);
+    expect(fetchedAlpha).not.toBeNull();
+    expect(fetchedAlpha?.name).toBe('Секретный контракт Альфа');
+
+    // 3. Fetch under tenant_beta -> rejected with TenantAccessDeniedError!
+    await expect(repository.getById(created.id, contextBeta)).rejects.toThrow(
+      TenantAccessDeniedError
+    );
+  });
+
+  it('Test 2: Querying list under tenant_beta returns 0 records when all records belong to tenant_alpha', async () => {
+    const contextAlpha = createRequestContext({ tenantId: 'tenant_alpha' });
+    const contextBeta = createRequestContext({ tenantId: 'tenant_beta' });
+
+    // 1. Create 3 records in tenant_alpha
+    await repository.create({ name: 'Альфа запись 1', amount: 100 }, contextAlpha);
+    await repository.create({ name: 'Альфа запись 2', amount: 200 }, contextAlpha);
+    await repository.create({ name: 'Альфа запись 3', amount: 300 }, contextAlpha);
+
+    // 2. List under tenant_alpha returns 3
+    const listAlpha = await repository.list(undefined, contextAlpha);
+    expect(listAlpha.total).toBe(3);
+    expect(listAlpha.items).toHaveLength(3);
+
+    // 3. List under tenant_beta returns 0
+    const listBeta = await repository.list(undefined, contextBeta);
+    expect(listBeta.total).toBe(0);
+    expect(listBeta.items).toHaveLength(0);
+  });
+
+  it('Test 3: Updating a record in tenant_alpha using a tenant_beta context is rejected with permission error', async () => {
+    const contextAlpha = createRequestContext({ tenantId: 'tenant_alpha' });
+    const contextBeta = createRequestContext({ tenantId: 'tenant_beta' });
+
+    // 1. Create in tenant_alpha
+    const created = await repository.create(
+      {
+        name: 'Оригинальный контракт',
+        amount: 1000,
+      },
+      contextAlpha
+    );
+
+    // 2. Attempt update from tenant_beta -> rejected
+    await expect(
+      repository.update(
+        created.id,
+        {
+          name: 'Взломанный контракт',
+          amount: 999999,
+        },
+        contextBeta
+      )
+    ).rejects.toThrow(TenantAccessDeniedError);
+
+    // 3. Verify original record was NOT modified
+    const original = await repository.getById(created.id, contextAlpha);
+    expect(original?.name).toBe('Оригинальный контракт');
+    expect(original?.amount).toBe(1000);
+  });
+
+  it('Test 4: Deleting a record in tenant_alpha using a tenant_beta context is rejected with permission error', async () => {
+    const contextAlpha = createRequestContext({ tenantId: 'tenant_alpha' });
+    const contextBeta = createRequestContext({ tenantId: 'tenant_beta' });
+
+    // 1. Create in tenant_alpha
+    const created = await repository.create(
+      {
+        name: 'Неудаляемый контракт',
+        amount: 2500,
+      },
+      contextAlpha
+    );
+
+    // 2. Attempt delete from tenant_beta -> rejected
+    await expect(repository.delete(created.id, contextBeta)).rejects.toThrow(
+      TenantAccessDeniedError
+    );
+
+    // 3. Verify record still exists in tenant_alpha
+    const stillExists = await repository.getById(created.id, contextAlpha);
+    expect(stillExists).not.toBeNull();
+  });
+
+  it('Test 5: Metadata custom fields, entities, and layouts in tenant_alpha do not leak into tenant_beta', async () => {
+    // 1. Create custom entity in tenant_alpha
+    const entityAlpha = await metadataService.createEntity(
+      {
+        code: 'alpha_custom_dossier',
+        name: 'Досье Альфа',
+        pluralName: 'Досье Альфа',
+        category: 'custom',
+        isSystem: false,
+        maturity: 'target_prototype',
+        fields: [],
+      },
+      'tenant_alpha'
+    );
+
+    // 2. Save layout in tenant_alpha
+    await metadataService.saveLayout(
+      {
+        id: 'layout_alpha_01',
+        entityCode: entityAlpha.code,
+        name: 'Форма Альфа',
+        isDefault: true,
+        sections: [],
+      },
+      'tenant_alpha'
+    );
+
+    // 3. List entities in tenant_alpha -> includes alpha_custom_dossier
+    const entitiesAlpha = await metadataService.listEntities('tenant_alpha');
+    expect(entitiesAlpha.some((e) => e.code === 'alpha_custom_dossier')).toBe(true);
+
+    // 4. List entities in tenant_beta -> does NOT include alpha_custom_dossier!
+    const entitiesBeta = await metadataService.listEntities('tenant_beta');
+    expect(entitiesBeta.some((e) => e.code === 'alpha_custom_dossier')).toBe(false);
+
+    // 5. Layouts in tenant_beta do not leak
+    const layoutsBeta = await metadataService.listLayouts(entityAlpha.code, 'tenant_beta');
+    expect(layoutsBeta.some((l) => l.id === 'layout_alpha_01')).toBe(false);
+  });
+
+  it('Test 6: Audit log entries record tenant_id and correlation_id', async () => {
+    const correlationId = 'corr_test_ulid_12345';
+    const context = createRequestContext({
+      tenantId: 'tenant_alpha',
+      actorId: 'usr_director',
+      correlationId,
+    });
+
+    // 1. Create record with custom context
+    const created = await repository.create(
+      {
+        name: 'Аудируемая операция',
+        amount: 777,
+      },
+      context
+    );
+
+    // 2. Check audit log store directly
+    const logs = (await getAllFromStore('audit_log', 'tenant_alpha')) as Record<string, unknown>[];
+    const logEntry = logs.find((l) => l.entityId === created.id);
+
+    expect(logEntry).toBeDefined();
+    expect(logEntry?.tenant_id).toBe('tenant_alpha');
+    expect(logEntry?.correlation_id).toBe(correlationId);
+    expect(logEntry?.userId).toBe('usr_director');
+  });
+
+  it('Test 7: Tenant-scoped Snapshot Export and Import maintains strict isolation', async () => {
+    const contextAlpha = createRequestContext({ tenantId: 'tenant_alpha' });
+    const contextBeta = createRequestContext({ tenantId: 'tenant_beta' });
+
+    // Create data in both tenants
+    await repository.create({ name: 'Alpha Data 1', amount: 10 }, contextAlpha);
+    await repository.create({ name: 'Alpha Data 2', amount: 20 }, contextAlpha);
+    await repository.create({ name: 'Beta Data 1', amount: 99 }, contextBeta);
+
+    // Export ONLY tenant_alpha
+    const snapshotAlpha = await exportDatabaseSnapshot('tenant_alpha');
+    expect(snapshotAlpha.metadata.totalRecords).toBe(2);
+    expect(snapshotAlpha.tenantId).toBe('tenant_alpha');
+    expect(
+      snapshotAlpha.stores.records_data.every(
+        (r) => (r as RecordEntity).tenant_id === 'tenant_alpha'
+      )
+    ).toBe(true);
+
+    // Import into tenant_gamma
+    await importDatabaseSnapshot(snapshotAlpha, 'tenant_gamma');
+
+    // tenant_gamma now has 2 records
+    const contextGamma = createRequestContext({ tenantId: 'tenant_gamma' });
+    const listGamma = await repository.list(undefined, contextGamma);
+    expect(listGamma.total).toBe(2);
+
+    // tenant_alpha still has 2 records
+    const listAlpha = await repository.list(undefined, contextAlpha);
+    expect(listAlpha.total).toBe(2);
+
+    // tenant_beta still has 1 record
+    const listBeta = await repository.list(undefined, contextBeta);
+    expect(listBeta.total).toBe(1);
+  });
+});
diff --git a/src/services/contracts/context.ts b/src/services/contracts/context.ts
new file mode 100644
index 0000000..22f8ed7
--- /dev/null
+++ b/src/services/contracts/context.ts
@@ -0,0 +1,54 @@
+import { ulid } from '../../shared/lib/ulid';
+
+export interface RequestContext {
+  tenantId: string;
+  actorId: string;
+  roleIds: string[];
+  correlationId: string;
+}
+
+export class TenantAccessDeniedError extends Error {
+  constructor(
+    message = 'Отказано в доступе: запись принадлежит другому тенанту или доступ ограничен'
+  ) {
+    super(message);
+    this.name = 'TenantAccessDeniedError';
+  }
+}
+
+export class NotFoundError extends Error {
+  constructor(message = 'Запрашиваемый ресурс не найден') {
+    super(message);
+    this.name = 'NotFoundError';
+  }
+}
+
+export const DEFAULT_TENANT_ID = 'tenant_main';
+export const DEFAULT_ACTOR_ID = 'usr_default';
+export const DEFAULT_ROLE_IDS = ['owner'];
+
+let activeGlobalTenantId = DEFAULT_TENANT_ID;
+
+export function getActiveGlobalTenantId(): string {
+  if (typeof window !== 'undefined') {
+    const stored = localStorage.getItem('krona_tenant_id');
+    if (stored) return stored;
+  }
+  return activeGlobalTenantId;
+}
+
+export function setActiveGlobalTenantId(tenantId: string): void {
+  activeGlobalTenantId = tenantId;
+  if (typeof window !== 'undefined') {
+    localStorage.setItem('krona_tenant_id', tenantId);
+  }
+}
+
+export function createRequestContext(overrides?: Partial<RequestContext>): RequestContext {
+  return {
+    tenantId: overrides?.tenantId || getActiveGlobalTenantId(),
+    actorId: overrides?.actorId || DEFAULT_ACTOR_ID,
+    roleIds: overrides?.roleIds || [...DEFAULT_ROLE_IDS],
+    correlationId: overrides?.correlationId || ulid(),
+  };
+}
diff --git a/src/services/contracts/index.ts b/src/services/contracts/index.ts
index 931dd7f..4c8d402 100644
--- a/src/services/contracts/index.ts
+++ b/src/services/contracts/index.ts
@@ -5,3 +5,4 @@ export * from './commerce';
 export * from './inventory';
 export * from './finance';
 export * from './metadata';
+export * from './context';
diff --git a/src/services/contracts/repository.ts b/src/services/contracts/repository.ts
index 4f14600..db2f073 100644
--- a/src/services/contracts/repository.ts
+++ b/src/services/contracts/repository.ts
@@ -1,3 +1,5 @@
+import { RequestContext } from './context';
+
 export interface QueryFilter {
   [field: string]: unknown;
 }
@@ -24,10 +26,11 @@ export interface PagedResult<T> {
 }
 
 export interface IRepository<T extends { id: string }> {
-  getById(id: string): Promise<T | null>;
-  list(options?: QueryOptions<T>): Promise<PagedResult<T>>;
-  create(data: Omit<T, 'id' | 'audit'>): Promise<T>;
-  update(id: string, data: Partial<T>): Promise<T>;
-  delete(id: string): Promise<boolean>;
-  count(filter?: QueryFilter): Promise<number>;
+  getById(id: string, context?: RequestContext): Promise<T | null>;
+  list(options?: QueryOptions<T>, context?: RequestContext): Promise<PagedResult<T>>;
+  create(data: Omit<T, 'id' | 'audit'>, context?: RequestContext): Promise<T>;
+  update(id: string, data: Partial<T>, context?: RequestContext): Promise<T>;
+  delete(id: string, context?: RequestContext): Promise<boolean>;
+  count(filter?: QueryFilter, context?: RequestContext): Promise<number>;
+  batchUpdate?(items: { id: string; data: Partial<T> }[], context?: RequestContext): Promise<T[]>;
 }
diff --git a/src/services/mock/baseRepository.ts b/src/services/mock/baseRepository.ts
index 7948277..872a144 100644
--- a/src/services/mock/baseRepository.ts
+++ b/src/services/mock/baseRepository.ts
@@ -1,10 +1,15 @@
 import { IRepository, QueryOptions, PagedResult, QueryFilter } from '../contracts/repository';
+import {
+  RequestContext,
+  TenantAccessDeniedError,
+  NotFoundError,
+  createRequestContext,
+} from '../contracts/context';
 import {
   getRecord,
   putRecord,
   deleteRecord,
   getRecordsByEntity,
-  countRecords,
   putStoreItem,
   RecordEntity,
 } from '../storage/indexedDb';
@@ -15,6 +20,10 @@ import { BaseEntity } from '../../entities/types';
 export class BaseMockRepository<T extends BaseEntity> implements IRepository<T> {
   constructor(protected entityName: string) {}
 
+  protected resolveContext(context?: RequestContext): RequestContext {
+    return context || createRequestContext();
+  }
+
   public async applySimulation(): Promise<void> {
     const { simulateLatency, latencyMs, simulateErrors, errorType } = useDemoStore.getState();
 
@@ -37,17 +46,28 @@ export class BaseMockRepository<T extends BaseEntity> implements IRepository<T>
     }
   }
 
-  async getById(id: string): Promise<T | null> {
+  async getById(id: string, context?: RequestContext): Promise<T | null> {
     await this.applySimulation();
-    const res = await getRecord<T & RecordEntity>(id);
+    const ctx = this.resolveContext(context);
+    const res = await getRecord<T & RecordEntity>(id, ctx.tenantId);
     if (!res || res.entityType !== this.entityName) {
       return null;
     }
+
+    // Tenant check: strictly prevent data leakage across tenants
+    const recordTenant = res.tenant_id || 'tenant_main';
+    if (recordTenant !== ctx.tenantId) {
+      throw new TenantAccessDeniedError(
+        `Отказано в доступе: запись «${this.entityName}» с ID ${id} принадлежит тенанту «${recordTenant}» (запрос от «${ctx.tenantId}»).`
+      );
+    }
+
     return res;
   }
 
-  async list(options?: QueryOptions<T>): Promise<PagedResult<T>> {
+  async list(options?: QueryOptions<T>, context?: RequestContext): Promise<PagedResult<T>> {
     await this.applySimulation();
+    const ctx = this.resolveContext(context);
 
     const sortOption = options?.sort
       ? { field: String(options.sort.field), order: options.sort.order }
@@ -59,6 +79,7 @@ export class BaseMockRepository<T extends BaseEntity> implements IRepository<T>
       sort: sortOption,
       page: options?.page,
       pageSize: options?.pageSize,
+      tenantId: ctx.tenantId,
     });
 
     return {
@@ -70,16 +91,18 @@ export class BaseMockRepository<T extends BaseEntity> implements IRepository<T>
     };
   }
 
-  async create(data: Omit<T, 'id' | 'audit'>): Promise<T> {
+  async create(data: Omit<T, 'id' | 'audit'>, context?: RequestContext): Promise<T> {
     await this.applySimulation();
+    const ctx = this.resolveContext(context);
     const now = useDemoStore.getState().demoDate || new Date().toISOString();
-    const userId = useDemoStore.getState().currentRoleId || 'demo_user';
+    const userId = ctx.actorId || useDemoStore.getState().currentRoleId || 'demo_user';
 
     const id = ulid();
     const entity = {
       ...data,
       id,
       entityType: this.entityName,
+      tenant_id: ctx.tenantId,
       updatedAt: now,
       audit: {
         createdAt: now,
@@ -87,100 +110,134 @@ export class BaseMockRepository<T extends BaseEntity> implements IRepository<T>
         updatedAt: now,
         updatedById: userId,
         version: 1,
+        tenantId: ctx.tenantId,
+        correlationId: ctx.correlationId,
       },
     } as unknown as T & RecordEntity;
 
-    await putRecord(entity);
+    await putRecord(entity, ctx.tenantId);
 
-    // Write audit log
-    await putStoreItem('audit_log', {
-      id: ulid(),
-      entityType: this.entityName,
-      entityId: id,
-      action: 'create',
-      userId,
-      userName: `Роль: ${userId}`,
-      timestamp: now,
-      summary: `Создана запись «${this.entityName}» (${id.slice(0, 8)}...)`,
-    });
+    // Write audit log with tenant & correlation tracing
+    await putStoreItem(
+      'audit_log',
+      {
+        id: ulid(),
+        entityType: this.entityName,
+        entityId: id,
+        tenant_id: ctx.tenantId,
+        correlation_id: ctx.correlationId,
+        action: 'create',
+        userId,
+        userName: `Роль: ${userId}`,
+        timestamp: now,
+        summary: `Создана запись «${this.entityName}» (${id.slice(0, 8)}...)`,
+      },
+      ctx.tenantId
+    );
 
     return entity as T;
   }
 
-  async update(id: string, data: Partial<T>): Promise<T> {
+  async update(id: string, data: Partial<T>, context?: RequestContext): Promise<T> {
     await this.applySimulation();
-    const existing = await this.getById(id);
+    const ctx = this.resolveContext(context);
+    const existing = await this.getById(id, ctx);
     if (!existing) {
-      throw new Error(`Запись «${this.entityName}» с ID ${id} не найдена.`);
+      throw new NotFoundError(`Запись «${this.entityName}» с ID ${id} не найдена.`);
     }
 
     const now = useDemoStore.getState().demoDate || new Date().toISOString();
-    const userId = useDemoStore.getState().currentRoleId || 'demo_user';
+    const userId = ctx.actorId || useDemoStore.getState().currentRoleId || 'demo_user';
 
     const updated = {
       ...existing,
       ...data,
       id,
       entityType: this.entityName,
+      tenant_id: ctx.tenantId,
       updatedAt: now,
       audit: {
         ...existing.audit,
         updatedAt: now,
         updatedById: userId,
         version: (existing.audit?.version || 1) + 1,
+        tenantId: ctx.tenantId,
+        correlationId: ctx.correlationId,
       },
     } as unknown as T & RecordEntity;
 
-    await putRecord(updated);
+    await putRecord(updated, ctx.tenantId);
 
-    // Write audit log
-    await putStoreItem('audit_log', {
-      id: ulid(),
-      entityType: this.entityName,
-      entityId: id,
-      action: 'update',
-      userId,
-      userName: `Роль: ${userId}`,
-      timestamp: now,
-      summary: `Обновлена запись «${this.entityName}» (${id.slice(0, 8)}...)`,
-    });
+    // Write audit log with tenant & correlation tracing
+    await putStoreItem(
+      'audit_log',
+      {
+        id: ulid(),
+        entityType: this.entityName,
+        entityId: id,
+        tenant_id: ctx.tenantId,
+        correlation_id: ctx.correlationId,
+        action: 'update',
+        userId,
+        userName: `Роль: ${userId}`,
+        timestamp: now,
+        summary: `Обновлена запись «${this.entityName}» (${id.slice(0, 8)}...)`,
+      },
+      ctx.tenantId
+    );
 
     return updated as T;
   }
 
-  async delete(id: string): Promise<boolean> {
+  async delete(id: string, context?: RequestContext): Promise<boolean> {
     await this.applySimulation();
-    const existing = await this.getById(id);
+    const ctx = this.resolveContext(context);
+    const existing = await this.getById(id, ctx);
     if (!existing) {
       return false;
     }
 
-    await deleteRecord(id, this.entityName);
+    await deleteRecord(id, this.entityName, ctx.tenantId);
 
     const now = useDemoStore.getState().demoDate || new Date().toISOString();
-    const userId = useDemoStore.getState().currentRoleId || 'demo_user';
+    const userId = ctx.actorId || useDemoStore.getState().currentRoleId || 'demo_user';
 
-    // Write audit log
-    await putStoreItem('audit_log', {
-      id: ulid(),
-      entityType: this.entityName,
-      entityId: id,
-      action: 'delete',
-      userId,
-      userName: `Роль: ${userId}`,
-      timestamp: now,
-      summary: `Удалена запись «${this.entityName}» (${id.slice(0, 8)}...)`,
-    });
+    // Write audit log with tenant & correlation tracing
+    await putStoreItem(
+      'audit_log',
+      {
+        id: ulid(),
+        entityType: this.entityName,
+        entityId: id,
+        tenant_id: ctx.tenantId,
+        correlation_id: ctx.correlationId,
+        action: 'delete',
+        userId,
+        userName: `Роль: ${userId}`,
+        timestamp: now,
+        summary: `Удалена запись «${this.entityName}» (${id.slice(0, 8)}...)`,
+      },
+      ctx.tenantId
+    );
 
     return true;
   }
 
-  async count(filter?: QueryFilter): Promise<number> {
-    await this.applySimulation();
-    if (!filter || Object.keys(filter).length === 0) {
-      return countRecords(this.entityName);
+  async batchUpdate(
+    items: { id: string; data: Partial<T> }[],
+    context?: RequestContext
+  ): Promise<T[]> {
+    const updated: T[] = [];
+    for (const item of items) {
+      const res = await this.update(item.id, item.data, context);
+      updated.push(res);
     }
-    const result = await this.list({ filter });
+    return updated;
+  }
+
+  async count(filter?: QueryFilter, context?: RequestContext): Promise<number> {
+    await this.applySimulation();
+    const result = await this.list({ filter }, context);
     return result.total;
   }
 }
diff --git a/src/services/mock/metadataService.ts b/src/services/mock/metadataService.ts
index b4bf3b0..c1f6260 100644
--- a/src/services/mock/metadataService.ts
+++ b/src/services/mock/metadataService.ts
@@ -13,29 +13,33 @@ import {
 } from '../storage/indexedDb';
 import { ulid } from '../../shared/lib/ulid';
 import { SYSTEM_ENTITY_METADATA } from '../../entities/metadata/registry';
+import { getActiveGlobalTenantId } from '../contracts/context';
 
 export class MockMetadataService implements IMetadataService {
-  async listEntities(): Promise<EntityMetadata[]> {
-    const fromDb = await getAllFromStore<EntityMetadata>('entities_meta');
+  async listEntities(tenantId?: string): Promise<EntityMetadata[]> {
+    const effectiveTenant = tenantId || getActiveGlobalTenantId();
+    const fromDb = await getAllFromStore<EntityMetadata & { tenant_id?: string }>('entities_meta', effectiveTenant);
     if (fromDb.length > 0) {
       return fromDb;
     }
     return Object.values(SYSTEM_ENTITY_METADATA);
   }
 
-  async getEntity(code: string): Promise<EntityMetadata | null> {
-    const list = await this.listEntities();
+  async getEntity(code: string, tenantId?: string): Promise<EntityMetadata | null> {
+    const list = await this.listEntities(tenantId);
     const cleanCode = code.trim().toLowerCase();
     return list.find((e) => e.code.trim().toLowerCase() === cleanCode) || null;
   }
 
-  async createEntity(metadata: Omit<EntityMetadata, 'id'>): Promise<EntityMetadata> {
+  async createEntity(metadata: Omit<EntityMetadata, 'id'>, tenantId?: string): Promise<EntityMetadata> {
     const id = ulid();
-    const entity: EntityMetadata = {
+    const effectiveTenant = tenantId || getActiveGlobalTenantId();
+    const entity: EntityMetadata & { tenant_id?: string } = {
       ...metadata,
       id,
+      tenant_id: ((metadata as Record<string, unknown>).tenant_id as string) || effectiveTenant,
     };
-    await putStoreItem('entities_meta', entity);
+    await putStoreItem('entities_meta', entity, effectiveTenant);
     return entity;
   }
 
@@ -104,10 +108,12 @@ export class MockMetadataService implements IMetadataService {
 
   async deleteField(entityCode: string, fieldId: string): Promise<boolean> {
     const entity = await this.getEntity(entityCode);
-    if (!entity) return false;
-    const targetField = entity.fields.find((f) => f.id === fieldId);
-    if (targetField?.system) {
-      throw new Error('Нельзя удалить системное поле сущности.');
+    if (!entity) {
+      throw new Error(`Сущность с кодом «${entityCode}» не найдена.`);
+    }
+    const field = entity.fields.find((f) => f.id === fieldId);
+    if (field?.system || (field as unknown as { isSystem?: boolean })?.isSystem) {
+      throw new Error('Нельзя удалить системное поле');
     }
     entity.fields = entity.fields.filter((f) => f.id !== fieldId);
     await putStoreItem('entities_meta', entity);
@@ -116,15 +122,18 @@ export class MockMetadataService implements IMetadataService {
   }
 
   // Layouts
-  async listLayouts(entityCode: string): Promise<LayoutDefinition[]> {
+  async listLayouts(entityCode: string, tenantId?: string): Promise<LayoutDefinition[]> {
+    const effectiveTenant = tenantId || getActiveGlobalTenantId();
     const db = await getDb();
     const tx = db.transaction('layouts_meta', 'readonly');
     const index = tx.store.index('by_entity');
-    const items = (await index.getAll(entityCode)) as LayoutDefinition[];
-    if (items.length > 0) return items;
+    const items = (await index.getAll(entityCode)) as (LayoutDefinition & { tenant_id?: string })[];
+    const filtered = items.filter(
+      (l) => !l.tenant_id || l.tenant_id === 'system' || l.tenant_id === effectiveTenant
+    );
+    if (filtered.length > 0) return filtered;
 
-    // Return a default fallback layout
-    const entity = await this.getEntity(entityCode);
+    const entity = await this.getEntity(entityCode, effectiveTenant);
     return [
       {
         id: `layout_def_${entityCode}`,
@@ -147,8 +156,13 @@ export class MockMetadataService implements IMetadataService {
     return getStoreItem<LayoutDefinition>('layouts_meta', id);
   }
 
-  async saveLayout(layout: LayoutDefinition): Promise<LayoutDefinition> {
-    await putStoreItem('layouts_meta', layout);
+  async saveLayout(layout: LayoutDefinition, tenantId?: string): Promise<LayoutDefinition> {
+    const effectiveTenant = tenantId || getActiveGlobalTenantId();
+    const withTenant = {
+      ...layout,
+      tenant_id: (layout as unknown as Record<string, unknown>).tenant_id || effectiveTenant,
+    };
+    await putStoreItem('layouts_meta', withTenant, effectiveTenant);
     return layout;
   }
 
@@ -158,14 +172,18 @@ export class MockMetadataService implements IMetadataService {
   }
 
   // Views
-  async listViews(entityCode: string): Promise<ViewDefinition[]> {
+  async listViews(entityCode: string, tenantId?: string): Promise<ViewDefinition[]> {
+    const effectiveTenant = tenantId || getActiveGlobalTenantId();
     const db = await getDb();
     const tx = db.transaction('views_meta', 'readonly');
     const index = tx.store.index('by_entity');
-    const items = (await index.getAll(entityCode)) as ViewDefinition[];
-    if (items.length > 0) return items;
+    const items = (await index.getAll(entityCode)) as (ViewDefinition & { tenant_id?: string })[];
+    const filtered = items.filter(
+      (v) => !v.tenant_id || v.tenant_id === 'system' || v.tenant_id === effectiveTenant
+    );
+    if (filtered.length > 0) return filtered;
 
-    const entity = await this.getEntity(entityCode);
+    const entity = await this.getEntity(entityCode, effectiveTenant);
     return [
       {
         id: `view_def_${entityCode}`,
@@ -183,8 +201,13 @@ export class MockMetadataService implements IMetadataService {
     return getStoreItem<ViewDefinition>('views_meta', id);
   }
 
-  async saveView(view: ViewDefinition): Promise<ViewDefinition> {
-    await putStoreItem('views_meta', view);
+  async saveView(view: ViewDefinition, tenantId?: string): Promise<ViewDefinition> {
+    const effectiveTenant = tenantId || getActiveGlobalTenantId();
+    const withTenant = {
+      ...view,
+      tenant_id: (view as unknown as Record<string, unknown>).tenant_id || effectiveTenant,
+    };
+    await putStoreItem('views_meta', withTenant, effectiveTenant);
     return view;
   }
 
diff --git a/src/services/storage/indexedDb.ts b/src/services/storage/indexedDb.ts
index 65ff94d..47a3811 100644
--- a/src/services/storage/indexedDb.ts
+++ b/src/services/storage/indexedDb.ts
@@ -1,5 +1,11 @@
 import { openDB, IDBPDatabase } from 'idb';
 import { storageEventBus } from './eventBus';
+import {
+  TenantAccessDeniedError,
+  DEFAULT_TENANT_ID,
+  getActiveGlobalTenantId,
+} from '../contracts/context';
+import { ulid } from '../../shared/lib/ulid';
 
 export const DB_NAME = 'krona_business_os_db';
 export const DB_VERSION = 2;
@@ -19,6 +25,7 @@ export type DbStoreName = (typeof DB_OBJECT_STORES)[number];
 export interface RecordEntity {
   id: string;
   entityType: string;
+  tenant_id?: string;
   updatedAt?: string;
   audit?: {
     createdAt: string;
@@ -26,6 +33,8 @@ export interface RecordEntity {
     updatedAt: string;
     updatedById: string;
     version: number;
+    tenantId?: string;
+    correlationId?: string;
   };
   [key: string]: unknown;
 }
@@ -35,6 +44,7 @@ export interface DatabaseSnapshot {
   schemaVersion: number;
   exportedAt: string;
   system: string;
+  tenantId?: string;
   stores: {
     entities_meta: unknown[];
     fields_meta: unknown[];
@@ -98,7 +108,7 @@ export function getDb(): Promise<IDBPDatabase> {
           s.createIndex('by_entity', 'entityCode', { unique: false });
         }
 
-        // 5. records_data (with indexes on entityType, id, updatedAt)
+        // 5. records_data (with indexes on entityType, id, updatedAt, tenant_id)
         if (!db.objectStoreNames.contains('records_data')) {
           const s = db.createObjectStore('records_data', { keyPath: 'id' });
           s.createIndex('by_entity_type', 'entityType', { unique: false });
@@ -124,19 +134,31 @@ export function getDb(): Promise<IDBPDatabase> {
 }
 
 // ----------------------------------------------------
-// CRUD on records_data
+// CRUD on records_data with Tenant Isolation
 // ----------------------------------------------------
 
-export async function getRecord<T = RecordEntity>(id: string): Promise<T | null> {
+export async function getRecord<T = RecordEntity>(id: string, tenantId?: string): Promise<T | null> {
   const db = await getDb();
   const res = await db.get('records_data', id);
-  return (res as T) || null;
+  if (!res) return null;
+
+  const rec = res as RecordEntity;
+  const effectiveTenantId = tenantId || getActiveGlobalTenantId();
+  if (effectiveTenantId && rec.tenant_id && rec.tenant_id !== effectiveTenantId) {
+    throw new TenantAccessDeniedError(
+      `Отказано в доступе: запись «${id}» принадлежит тенанту «${rec.tenant_id}», текущий: «${effectiveTenantId}»`
+    );
+  }
+
+  return res as T;
 }
 
-export async function putRecord<T extends RecordEntity>(record: T): Promise<T> {
+export async function putRecord<T extends RecordEntity>(record: T, tenantId?: string): Promise<T> {
   const db = await getDb();
+  const effectiveTenantId = record.tenant_id || tenantId || getActiveGlobalTenantId() || DEFAULT_TENANT_ID;
   const clean = {
     ...record,
+    tenant_id: effectiveTenantId,
     updatedAt: record.updatedAt || new Date().toISOString(),
   };
   await db.put('records_data', clean);
@@ -150,11 +172,19 @@ export async function putRecord<T extends RecordEntity>(record: T): Promise<T> {
   return clean as T;
 }
 
-export async function deleteRecord(id: string, entityType?: string): Promise<boolean> {
+export async function deleteRecord(id: string, entityType?: string, tenantId?: string): Promise<boolean> {
   const db = await getDb();
   const existing = await db.get('records_data', id);
   if (!existing) return false;
 
+  const rec = existing as RecordEntity;
+  const effectiveTenantId = tenantId || getActiveGlobalTenantId();
+  if (effectiveTenantId && rec.tenant_id && rec.tenant_id !== effectiveTenantId) {
+    throw new TenantAccessDeniedError(
+      `Отказано в доступе: запись «${id}» принадлежит тенанту «${rec.tenant_id}», текущий: «${effectiveTenantId}»`
+    );
+  }
+
   await db.delete('records_data', id);
   storageEventBus.emit('records:changed', {
     storeName: 'records_data',
@@ -173,12 +203,22 @@ export async function getRecordsByEntity<T = RecordEntity>(
     sort?: { field: string; order: 'asc' | 'desc' };
     page?: number;
     pageSize?: number;
+    tenantId?: string;
   }
 ): Promise<{ items: T[]; total: number; page: number; pageSize: number; totalPages: number }> {
   const db = await getDb();
   const tx = db.transaction('records_data', 'readonly');
   const index = tx.store.index('by_entity_type');
-  let all = (await index.getAll(entityType)) as T[];
+  let all = (await index.getAll(entityType)) as (T & RecordEntity)[];
+
+  // 0. Tenant isolation filter
+  const targetTenantId = options?.tenantId !== undefined ? options.tenantId : getActiveGlobalTenantId();
+  if (targetTenantId) {
+    all = all.filter((item) => {
+      const itemTenant = item.tenant_id || DEFAULT_TENANT_ID;
+      return itemTenant === targetTenantId;
+    });
+  }
 
   // 1. Filter
   if (options?.filter) {
@@ -235,18 +275,22 @@ export async function getRecordsByEntity<T = RecordEntity>(
   return { items, total, page, pageSize, totalPages };
 }
 
-export async function countRecords(entityType?: string): Promise<number> {
+export async function countRecords(entityType?: string, tenantId?: string): Promise<number> {
+  const effectiveTenantId = tenantId !== undefined ? tenantId : getActiveGlobalTenantId();
+  if (entityType) {
+    const res = await getRecordsByEntity(entityType, { tenantId: effectiveTenantId });
+    return res.total;
+  }
   const db = await getDb();
-  if (!entityType) {
+  if (!effectiveTenantId) {
     return db.count('records_data');
   }
-  const tx = db.transaction('records_data', 'readonly');
-  const index = tx.store.index('by_entity_type');
-  return index.count(entityType);
+  const all = (await db.getAll('records_data')) as RecordEntity[];
+  return all.filter((r) => (r.tenant_id || DEFAULT_TENANT_ID) === effectiveTenantId).length;
 }
 
 // ----------------------------------------------------
-// Generic Store Helpers
+// Generic Store Helpers with Optional Tenant Tagging
 // ----------------------------------------------------
 
 export async function getStoreItem<T>(storeName: DbStoreName, key: string): Promise<T | null> {
@@ -255,12 +299,18 @@ export async function getStoreItem<T>(storeName: DbStoreName, key: string): Prom
   return (res as T) || null;
 }
 
-export async function putStoreItem<T>(storeName: DbStoreName, item: T): Promise<void> {
+export async function putStoreItem<T>(storeName: DbStoreName, item: T, tenantId?: string): Promise<void> {
   const db = await getDb();
-  await db.put(storeName, item);
+  const effectiveTenant = tenantId || getActiveGlobalTenantId() || DEFAULT_TENANT_ID;
+  const cleanItem =
+    typeof item === 'object' && item !== null
+      ? { ...item, tenant_id: (item as Record<string, unknown>).tenant_id || effectiveTenant }
+      : item;
+
+  await db.put(storeName, cleanItem);
   storageEventBus.emit('entity:changed', {
     storeName,
-    data: item,
+    data: cleanItem,
     action: 'update',
   });
 }
@@ -275,9 +325,26 @@ export async function deleteStoreItem(storeName: DbStoreName, key: string): Prom
   });
 }
 
-export async function getAllFromStore<T>(storeName: DbStoreName): Promise<T[]> {
+export async function getAllFromStore<T>(storeName: DbStoreName, tenantId?: string): Promise<T[]> {
   const db = await getDb();
-  return db.getAll(storeName);
+  const all = (await db.getAll(storeName)) as (T & Record<string, unknown>)[];
+
+  if (!tenantId) {
+    return all as T[];
+  }
+
+  // Filter items by tenant
+  if (storeName === 'entities_meta' || storeName === 'layouts_meta' || storeName === 'views_meta') {
+    return all.filter(
+      (item) => !item.tenant_id || item.tenant_id === 'system' || item.tenant_id === tenantId
+    ) as T[];
+  }
+
+  if (storeName === 'audit_log' || storeName === 'records_data') {
+    return all.filter((item) => (item.tenant_id || DEFAULT_TENANT_ID) === tenantId) as T[];
+  }
+
+  return all as T[];
 }
 
 export async function countStore(storeName: DbStoreName): Promise<number> {
@@ -291,25 +358,41 @@ export async function clearStore(storeName: DbStoreName): Promise<void> {
 }
 
 // ----------------------------------------------------
-// Snapshot Export / Import / Reset
+// Snapshot Export / Import / Reset with Tenant Support
 // ----------------------------------------------------
 
-export async function exportDatabaseSnapshot(): Promise<DatabaseSnapshot> {
+export async function exportDatabaseSnapshot(tenantId?: string): Promise<DatabaseSnapshot> {
   const db = await getDb();
 
-  const entities_meta = await db.getAll('entities_meta');
-  const fields_meta = await db.getAll('fields_meta');
-  const layouts_meta = await db.getAll('layouts_meta');
-  const views_meta = await db.getAll('views_meta');
-  const records_data = await db.getAll('records_data');
-  const audit_log = await db.getAll('audit_log');
-  const settings = await db.getAll('settings');
+  let entities_meta = (await db.getAll('entities_meta')) as Record<string, unknown>[];
+  let fields_meta = (await db.getAll('fields_meta')) as Record<string, unknown>[];
+  let layouts_meta = (await db.getAll('layouts_meta')) as Record<string, unknown>[];
+  let views_meta = (await db.getAll('views_meta')) as Record<string, unknown>[];
+  let records_data = (await db.getAll('records_data')) as RecordEntity[];
+  let audit_log = (await db.getAll('audit_log')) as Record<string, unknown>[];
+  let settings = (await db.getAll('settings')) as Record<string, unknown>[];
+
+  if (tenantId) {
+    records_data = records_data.filter((r) => (r.tenant_id || DEFAULT_TENANT_ID) === tenantId);
+    audit_log = audit_log.filter((a) => (a.tenant_id || DEFAULT_TENANT_ID) === tenantId);
+    entities_meta = entities_meta.filter(
+      (e) => !e.tenant_id || e.tenant_id === 'system' || e.tenant_id === tenantId
+    );
+    layouts_meta = layouts_meta.filter(
+      (l) => !l.tenant_id || l.tenant_id === 'system' || l.tenant_id === tenantId
+    );
+    views_meta = views_meta.filter(
+      (v) => !v.tenant_id || v.tenant_id === 'system' || v.tenant_id === tenantId
+    );
+    settings = settings.filter((s) => !s.tenant_id || s.tenant_id === tenantId);
+  }
 
   return {
     version: 1,
     schemaVersion: DB_VERSION,
     exportedAt: new Date().toISOString(),
     system: 'Krona Universal Business OS',
+    tenantId: tenantId || 'all',
     stores: {
       entities_meta,
       fields_meta,
@@ -327,7 +410,10 @@ export async function exportDatabaseSnapshot(): Promise<DatabaseSnapshot> {
   };
 }
 
-export async function importDatabaseSnapshot(snapshot: DatabaseSnapshot): Promise<void> {
+export async function importDatabaseSnapshot(
+  snapshot: DatabaseSnapshot,
+  targetTenantId?: string
+): Promise<void> {
   if (!snapshot || typeof snapshot !== 'object') {
     throw new Error('Некорректный формат снимка базы данных (snapshot).');
   }
@@ -338,12 +424,77 @@ export async function importDatabaseSnapshot(snapshot: DatabaseSnapshot): Promis
   const db = await getDb();
   const tx = db.transaction(DB_OBJECT_STORES as unknown as string[], 'readwrite');
 
-  for (const store of DB_OBJECT_STORES) {
-    const storeObj = tx.objectStore(store);
-    await storeObj.clear();
-    const items = snapshot.stores[store] || [];
-    for (const item of items) {
-      await storeObj.put(item);
+  if (!targetTenantId) {
+    // Global wipe & restore
+    for (const store of DB_OBJECT_STORES) {
+      const storeObj = tx.objectStore(store);
+      await storeObj.clear();
+      const items = snapshot.stores[store] || [];
+      for (const item of items) {
+        await storeObj.put(item);
+      }
+    }
+  } else {
+    // Isolated tenant import: delete only target tenant records, keep other tenants safe
+    const recordsStore = tx.objectStore('records_data');
+    const existingRecords = (await recordsStore.getAll()) as RecordEntity[];
+    for (const r of existingRecords) {
+      if ((r.tenant_id || DEFAULT_TENANT_ID) === targetTenantId) {
+        await recordsStore.delete(r.id);
+      }
+    }
+    const newRecords = (snapshot.stores.records_data || []) as RecordEntity[];
+    const idMap = new Map<string, string>();
+    for (const r of newRecords) {
+      const isCrossTenantClone = Boolean(
+        targetTenantId && snapshot.tenantId && targetTenantId !== snapshot.tenantId
+      );
+      const idConflict = existingRecords.some(
+        (er) => er.id === r.id && (er.tenant_id || DEFAULT_TENANT_ID) !== targetTenantId
+      );
+      const newId = isCrossTenantClone || idConflict ? ulid() : r.id;
+      idMap.set(r.id, newId);
+      await recordsStore.put({ ...r, id: newId, tenant_id: targetTenantId });
+    }
+
+    // Audit log
+    const auditStore = tx.objectStore('audit_log');
+    const existingAudit = (await auditStore.getAll()) as Record<string, unknown>[];
+    for (const a of existingAudit) {
+      if ((a.tenant_id || DEFAULT_TENANT_ID) === targetTenantId) {
+        await auditStore.delete(String(a.id));
+      }
+    }
+    const newAudit = (snapshot.stores.audit_log || []) as Record<string, unknown>[];
+    for (const a of newAudit) {
+      const mappedEntityId = a.entityId ? (idMap.get(String(a.entityId)) || a.entityId) : a.entityId;
+      const isCrossTenantClone = Boolean(
+        targetTenantId && snapshot.tenantId && targetTenantId !== snapshot.tenantId
+      );
+      const newId = isCrossTenantClone ? ulid() : (a.id as string);
+      await auditStore.put({
+        ...a,
+        id: newId,
+        entityId: mappedEntityId,
+        tenant_id: targetTenantId,
+      });
+    }
+
+    // Metadata: entities, fields, layouts, views
+    for (const store of ['entities_meta', 'fields_meta', 'layouts_meta', 'views_meta', 'settings'] as const) {
+      const s = tx.objectStore(store);
+      const items = (snapshot.stores[store] || []) as Record<string, unknown>[];
+      for (const item of items) {
+        if (!item.tenant_id || item.tenant_id === 'system') {
+          await s.put(item);
+        } else {
+          const isCrossTenantClone = Boolean(
+            targetTenantId && snapshot.tenantId && targetTenantId !== snapshot.tenantId
+          );
+          const newId = isCrossTenantClone && item.id ? ulid() : item.id;
+          await s.put({ ...item, id: newId, tenant_id: targetTenantId });
+        }
+      }
     }
   }
 
@@ -355,13 +506,34 @@ export async function importDatabaseSnapshot(snapshot: DatabaseSnapshot): Promis
   });
 }
 
-export async function resetDatabase(): Promise<void> {
+export async function resetDatabase(tenantId?: string): Promise<void> {
   const db = await getDb();
-  const tx = db.transaction(DB_OBJECT_STORES as unknown as string[], 'readwrite');
-  for (const store of DB_OBJECT_STORES) {
-    await tx.objectStore(store).clear();
+
+  if (!tenantId) {
+    const tx = db.transaction(DB_OBJECT_STORES as unknown as string[], 'readwrite');
+    for (const store of DB_OBJECT_STORES) {
+      await tx.objectStore(store).clear();
+    }
+    await tx.done;
+  } else {
+    // Only wipe data belonging to the specified tenant
+    const tx = db.transaction(['records_data', 'audit_log'] as const, 'readwrite');
+    const recordsStore = tx.objectStore('records_data');
+    const allRecords = (await recordsStore.getAll()) as RecordEntity[];
+    for (const r of allRecords) {
+      if ((r.tenant_id || DEFAULT_TENANT_ID) === tenantId) {
+        await recordsStore.delete(r.id);
+      }
+    }
+    const auditStore = tx.objectStore('audit_log');
+    const allAudit = (await auditStore.getAll()) as Record<string, unknown>[];
+    for (const a of allAudit) {
+      if ((a.tenant_id || DEFAULT_TENANT_ID) === tenantId) {
+        await auditStore.delete(String(a.id));
+      }
+    }
+    await tx.done;
   }
-  await tx.done;
 
   storageEventBus.emit('storage:reset', {
     action: 'reset',