diff --git a/frontend/e2e/workflows/5-offline-sync.spec.ts b/frontend/e2e/workflows/5-offline-sync.spec.ts
new file mode 100644
index 00000000..09181e45
--- /dev/null
+++ b/frontend/e2e/workflows/5-offline-sync.spec.ts
@@ -0,0 +1,353 @@
+import { test, expect } from '@playwright/test';
+import * as auth from '../fixtures/auth';
+import * as assertions from '../utils/assertions';
+import * as helpers from '../utils/helpers';
+import { LOCAL_USERS, TEST_ITEMS, OFFLINE_SYNC_SCENARIOS } from '../fixtures/test-data';
+
+test.describe('Offline Sync Workflow', () => {
+  const BASE_URL = process.env.BASE_URL || 'http://localhost:3000';
+
+  test.beforeEach(async ({ page }) => {
+    // Navigate to app and login
+    await page.goto(BASE_URL);
+    await auth.loginWithLocalUser(page, LOCAL_USERS.admin, BASE_URL);
+    await assertions.assertUserAuthenticated(page, BASE_URL);
+
+    // Navigate to scanner (offline operations page)
+    await page.goto(`${BASE_URL}/scanner`);
+  });
+
+  test('should detect offline mode when network is unavailable', async ({ page, context }) => {
+    // Enable offline mode
+    await context.setOffline(true);
+
+    // Wait for offline indicator to appear
+    const offlineIndicator = page.locator('[data-testid="offline-indicator"]');
+    await expect(offlineIndicator).toBeVisible({ timeout: 5000 });
+
+    // Disable offline mode
+    await context.setOffline(false);
+  });
+
+  test('should show offline sync indicator when operations are queued', async ({ page, context }) => {
+    // Perform a scan operation while offline
+    await context.setOffline(true);
+
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    // Complete adjustment
+    const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('5');
+
+    const submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Offline sync indicator should appear
+    const syncIndicator = page.locator('[data-testid="offline-sync-indicator"]');
+    await expect(syncIndicator).toBeVisible({ timeout: 5000 });
+
+    // Pending badge should show
+    const pendingBadge = page.locator('[data-testid="sync-pending-badge"]');
+    await expect(pendingBadge).toBeVisible();
+
+    await context.setOffline(false);
+  });
+
+  test('should queue operations when offline', async ({ page, context }) => {
+    // Go offline
+    await context.setOffline(true);
+
+    // Perform multiple operations
+    for (let i = 0; i < 2; i++) {
+      const scanInput = page.locator('[data-testid="scan-input"]');
+      await scanInput.fill(TEST_ITEMS[i].barcode);
+      await scanInput.press('Enter');
+
+      const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+      await quantityInput.fill('5');
+
+      const submitButton = page.locator('[data-testid="adjustment-submit"]');
+      await submitButton.click();
+
+      // Wait for form to close
+      const form = page.locator('[data-testid="stock-adjustment-form"]');
+      await expect(form).not.toBeVisible({ timeout: 5000 });
+    }
+
+    // Go back online
+    await context.setOffline(false);
+
+    // Sync should start automatically
+    const syncIndicator = page.locator('[data-testid="offline-sync-indicator"]');
+    if (await syncIndicator.isVisible()) {
+      // Wait for sync to complete
+      await expect(syncIndicator).not.toBeVisible({ timeout: 15000 });
+    }
+  });
+
+  test('should sync pending operations when connection is restored', async ({ page, context }) => {
+    // Perform operation offline
+    await context.setOffline(true);
+
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('5');
+
+    const submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Verify pending indicator
+    const pendingBadge = page.locator('[data-testid="sync-pending-badge"]');
+    await expect(pendingBadge).toBeVisible();
+
+    // Go online
+    await context.setOffline(false);
+
+    // Sync should start automatically
+    const successToast = page.locator('[data-testid="toast-success"]');
+    await expect(successToast).toBeVisible({ timeout: 15000 });
+
+    // Pending badge should disappear
+    await expect(pendingBadge).not.toBeVisible({ timeout: 5000 });
+  });
+
+  test('should show sync progress during offline sync', async ({ page, context }) => {
+    // Queue multiple operations
+    await context.setOffline(true);
+
+    for (let i = 0; i < 3; i++) {
+      const scanInput = page.locator('[data-testid="scan-input"]');
+      await scanInput.fill(TEST_ITEMS[i].barcode);
+      await scanInput.press('Enter');
+
+      const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+      await quantityInput.fill('5');
+
+      const submitButton = page.locator('[data-testid="adjustment-submit"]');
+      await submitButton.click();
+
+      const form = page.locator('[data-testid="stock-adjustment-form"]');
+      await expect(form).not.toBeVisible({ timeout: 5000 });
+    }
+
+    // Go online
+    await context.setOffline(false);
+
+    // Sync progress should be shown
+    const syncProgress = page.locator('[data-testid="sync-progress"]');
+    if (await syncProgress.isVisible({ timeout: 1000 }).catch(() => false)) {
+      const progressText = await syncProgress.textContent();
+      expect(progressText).toMatch(/\d+\/\d+|in progress|syncing/i);
+    }
+  });
+
+  test('should prevent duplicate operations during sync', async ({ page, context }) => {
+    // Perform operation offline
+    await context.setOffline(true);
+
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('5');
+
+    const submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Go online - sync starts
+    await context.setOffline(false);
+
+    // Should sync once without duplication
+    const successToast = page.locator('[data-testid="toast-success"]');
+    await expect(successToast).toBeVisible({ timeout: 15000 });
+
+    // UUID tracking should prevent duplicates (verified through API)
+    // Item quantity should only be incremented by 5, not 10
+  });
+
+  test('should handle sync failures gracefully', async ({ page, context }) => {
+    // Queue operation
+    await context.setOffline(true);
+
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('5');
+
+    const submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Go online but mock API to fail
+    await context.setOffline(false);
+    await page.route('**/api/bulk_sync', (route) => {
+      route.abort('failed');
+    });
+
+    // Trigger sync
+    const syncButton = page.locator('[data-testid="manual-sync-button"]');
+    if (await syncButton.isVisible()) {
+      await syncButton.click();
+    } else {
+      await page.reload();
+    }
+
+    // Should show error but keep operations queued
+    const errorToast = page.locator('[data-testid="toast-error"]');
+    await expect(errorToast).toBeVisible({ timeout: 10000 });
+
+    const pendingBadge = page.locator('[data-testid="sync-pending-badge"]');
+    await expect(pendingBadge).toBeVisible();
+  });
+
+  test('should allow manual sync trigger', async ({ page }) => {
+    const syncButton = page.locator('[data-testid="manual-sync-button"]');
+    if (await syncButton.isVisible()) {
+      await syncButton.click();
+
+      // Sync should complete (no pending operations)
+      const syncIndicator = page.locator('[data-testid="offline-sync-indicator"]');
+      await expect(syncIndicator).not.toBeVisible({ timeout: 10000 });
+    }
+  });
+
+  test('should display sync queue status', async ({ page, context }) => {
+    // Go offline and queue operations
+    await context.setOffline(true);
+
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('5');
+
+    const submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Queue status should be shown
+    const queueStatus = page.locator('[data-testid="queue-status"]');
+    if (await queueStatus.isVisible()) {
+      const statusText = await queueStatus.textContent();
+      expect(statusText).toMatch(/\d+.*queued|pending|offline/i);
+    }
+
+    await context.setOffline(false);
+  });
+
+  test('should persist queue to IndexedDB', async ({ page, context }) => {
+    // Queue operation offline
+    await context.setOffline(true);
+
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('5');
+
+    const submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Go online and verify queue is still there
+    await context.setOffline(false);
+
+    const pendingBadge = page.locator('[data-testid="sync-pending-badge"]');
+    await expect(pendingBadge).toBeVisible();
+
+    // Reload page - queue should persist
+    await page.reload();
+    await auth.waitForAuth(page);
+
+    // Badge should still show pending operations
+    await expect(pendingBadge).toBeVisible({ timeout: 5000 });
+  });
+
+  test('should show sync history', async ({ page }) => {
+    const syncHistory = page.locator('[data-testid="sync-history"]');
+    if (await syncHistory.isVisible()) {
+      const historyItems = page.locator('[data-testid="sync-history-item"]');
+      const count = await historyItems.count();
+
+      if (count > 0) {
+        // Verify history item shows timestamp and status
+        const firstItem = historyItems.first();
+        const itemText = await firstItem.textContent();
+        expect(itemText).toBeTruthy();
+      }
+    }
+  });
+
+  test('should handle mixed online/offline operations', async ({ page, context }) => {
+    // Start online - perform operation
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    let quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('3');
+
+    let submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Verify success
+    let successToast = page.locator('[data-testid="toast-success"]');
+    await expect(successToast).toBeVisible({ timeout: 5000 });
+
+    // Go offline
+    await context.setOffline(true);
+
+    // Perform offline operation
+    await scanInput.fill(TEST_ITEMS[1].barcode);
+    await scanInput.press('Enter');
+
+    quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('2');
+
+    submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Pending indicator should appear
+    const pendingBadge = page.locator('[data-testid="sync-pending-badge"]');
+    await expect(pendingBadge).toBeVisible();
+
+    // Go back online
+    await context.setOffline(false);
+
+    // Only offline operation should be synced
+    const syncIndicator = page.locator('[data-testid="offline-sync-indicator"]');
+    if (await syncIndicator.isVisible({ timeout: 1000 }).catch(() => false)) {
+      await expect(syncIndicator).not.toBeVisible({ timeout: 10000 });
+    }
+  });
+
+  test('should warn user before losing offline data', async ({ page, context }) => {
+    // Queue operation offline
+    await context.setOffline(true);
+
+    const scanInput = page.locator('[data-testid="scan-input"]');
+    await scanInput.fill(TEST_ITEMS[0].barcode);
+    await scanInput.press('Enter');
+
+    const quantityInput = page.locator('[data-testid="adjustment-quantity-input"]');
+    await quantityInput.fill('5');
+
+    const submitButton = page.locator('[data-testid="adjustment-submit"]');
+    await submitButton.click();
+
+    // Try to close tab or navigate away
+    const closeWarning = page.on('beforeunload', (dialog) => {
+      dialog.accept(); // Accept the warning
+    });
+
+    // Navigate away
+    await page.goto(`${BASE_URL}/inventory`);
+  });
+});