diff --git a/frontend/testing/unit/pages/Scans.failures.test.tsx b/frontend/testing/unit/pages/Scans.failures.test.tsx
new file mode 100644
index 000000000..5d4e5cc37
--- /dev/null
+++ b/frontend/testing/unit/pages/Scans.failures.test.tsx
@@ -0,0 +1,194 @@
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MemoryRouter } from 'react-router-dom';
+import { vi, describe, it, expect, beforeEach, afterEach } from 'vitest';
+import Scans from '../../../src/pages/Scans';
+import { ToastProvider } from '../../../src/components/ToastContext';
+
+vi.mock('../../../src/api', () => ({
+  API_BASE: 'http://localhost',
+  deleteTask: vi.fn(),
+  clearAllTasks: vi.fn(),
+  bulkDeleteTasks: vi.fn(),
+}));
+
+vi.mock('react-router-dom', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('react-router-dom')>();
+  return { ...actual, useNavigate: () => vi.fn() };
+});
+
+const COMPLETED_TASK = {
+  task_id: 'task-abc-123',
+  plugin_id: 'nmap',
+  tool: 'Nmap Scanner',
+  target: 'example.com',
+  status: 'completed' as const,
+  created_at: '2026-05-29T10:00:00Z',
+};
+
+const ONE_TASK_RESPONSE = {
+  tasks: [COMPLETED_TASK],
+  pagination: { total_items: 1 },
+};
+
+const TWO_TASK_RESPONSE = {
+  tasks: [
+    COMPLETED_TASK,
+    { ...COMPLETED_TASK, task_id: 'task-def-456', tool: 'Second Scanner' },
+  ],
+  pagination: { total_items: 2 },
+};
+
+function renderScans() {
+  return render(
+    <MemoryRouter>
+      <ToastProvider>
+        <Scans />
+      </ToastProvider>
+    </MemoryRouter>,
+  );
+}
+
+async function waitForTasks(toolName: string) {
+  await screen.findByText(toolName, {}, { timeout: 3000 });
+}
+
+async function expandTask(toolName: string) {
+  const card = await screen.findByText(toolName);
+  fireEvent.click(card);
+  await screen.findByRole('button', { name: /delete_record/i });
+}
+
+async function clickConfirm() {
+  const confirmBtn = await screen.findByRole('button', { name: /^confirm$/i });
+  fireEvent.click(confirmBtn);
+}
+
+beforeEach(() => {
+  vi.useRealTimers();
+  Object.defineProperty(document, 'visibilityState', {
+    configurable: true,
+    get: () => 'visible',
+  });
+});
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+describe('Scans — destructive-action failure feedback', () => {
+  describe('handleTaskDelete failure', () => {
+    beforeEach(() => {
+      vi.stubGlobal('fetch', vi.fn().mockResolvedValue({
+        ok: true,
+        json: () => Promise.resolve(ONE_TASK_RESPONSE),
+      }));
+    });
+
+    it('shows an error toast when deleteTask rejects', async () => {
+      const { deleteTask } = await import('../../../src/api');
+      vi.mocked(deleteTask).mockRejectedValueOnce(new Error('backend crash'));
+
+      renderScans();
+      await waitForTasks('Nmap Scanner');
+      await expandTask('Nmap Scanner');
+
+      fireEvent.click(screen.getByRole('button', { name: /delete_record/i }));
+      await clickConfirm();
+
+      await waitFor(() => {
+        expect(screen.getByRole('alert')).toBeInTheDocument();
+      });
+      expect(screen.getByText(/failed to delete task/i)).toBeInTheDocument();
+    });
+
+    it('does not remove the task from the list when deleteTask rejects', async () => {
+      const { deleteTask } = await import('../../../src/api');
+      vi.mocked(deleteTask).mockRejectedValueOnce(new Error('network error'));
+
+      renderScans();
+      await waitForTasks('Nmap Scanner');
+      await expandTask('Nmap Scanner');
+
+      fireEvent.click(screen.getByRole('button', { name: /delete_record/i }));
+      await clickConfirm();
+
+      await waitFor(() => {
+        expect(screen.getByRole('alert')).toBeInTheDocument();
+      });
+      expect(screen.getByText('Nmap Scanner')).toBeInTheDocument();
+    });
+  });
+
+  describe('handleBulkDelete failure', () => {
+    beforeEach(() => {
+      vi.stubGlobal('fetch', vi.fn().mockResolvedValue({
+        ok: true,
+        json: () => Promise.resolve(TWO_TASK_RESPONSE),
+      }));
+    });
+
+    it('shows an error toast when bulkDeleteTasks rejects', async () => {
+      const { bulkDeleteTasks } = await import('../../../src/api');
+      vi.mocked(bulkDeleteTasks).mockRejectedValueOnce(new Error('bulk delete failed'));
+
+      renderScans();
+      await waitForTasks('Nmap Scanner');
+
+      fireEvent.click(screen.getByRole('button', { name: /select_all/i }));
+
+      const bulkBtn = await screen.findByRole('button', { name: /prune_selected_records/i });
+      fireEvent.click(bulkBtn);
+      await clickConfirm();
+
+      await waitFor(() => {
+        expect(screen.getByRole('alert')).toBeInTheDocument();
+      });
+      expect(screen.getByText(/failed to delete some tasks/i)).toBeInTheDocument();
+    });
+
+    it('keeps tasks in the list when bulkDeleteTasks rejects', async () => {
+      const { bulkDeleteTasks } = await import('../../../src/api');
+      vi.mocked(bulkDeleteTasks).mockRejectedValueOnce(new Error('bulk delete failed'));
+
+      renderScans();
+      await waitForTasks('Nmap Scanner');
+
+      fireEvent.click(screen.getByRole('button', { name: /select_all/i }));
+
+      const bulkBtn = await screen.findByRole('button', { name: /prune_selected_records/i });
+      fireEvent.click(bulkBtn);
+      await clickConfirm();
+
+      await waitFor(() => {
+        expect(screen.getByRole('alert')).toBeInTheDocument();
+      });
+      expect(screen.getByText('Nmap Scanner')).toBeInTheDocument();
+      expect(screen.getByText('Second Scanner')).toBeInTheDocument();
+    });
+  });
+
+  describe('handleClearAll failure', () => {
+    beforeEach(() => {
+      vi.stubGlobal('fetch', vi.fn().mockResolvedValue({
+        ok: true,
+        json: () => Promise.resolve(ONE_TASK_RESPONSE),
+      }));
+    });
+
+    it('shows an error toast when clearAllTasks rejects', async () => {
+      const { clearAllTasks } = await import('../../../src/api');
+      vi.mocked(clearAllTasks).mockRejectedValueOnce(new Error('tasks still running'));
+
+      renderScans();
+      await waitForTasks('Nmap Scanner');
+
+      fireEvent.click(screen.getByRole('button', { name: /purge_all_records/i }));
+      await clickConfirm();
+
+      await waitFor(() => {
+        expect(screen.getByRole('alert')).toBeInTheDocument();
+      });
+      expect(screen.getByText(/failed to clear history/i)).toBeInTheDocument();
+    });
+  });
+});
\ No newline at end of file
diff --git a/frontend/testing/unit/pages/Scans.polling.test.tsx b/frontend/testing/unit/pages/Scans.polling.test.tsx
index 84480880c..b63e59892 100644
--- a/frontend/testing/unit/pages/Scans.polling.test.tsx
+++ b/frontend/testing/unit/pages/Scans.polling.test.tsx
@@ -6,6 +6,11 @@ import { ToastProvider } from '../../../src/components/ToastContext'
 
 // ── Mocks ────────────────────────────────────────────────────────────────────
 
+vi.mock('../../../src/components/ToastContext', () => ({
+  useToast: () => ({ addToast: vi.fn(), removeToast: vi.fn() }),
+  ToastProvider: ({ children }: any) => children,
+}));
+
 vi.mock('../../../src/api', () => ({
   API_BASE: 'http://localhost',
   deleteTask: vi.fn(),
diff --git a/frontend/testing/unit/pages/ScansPhases.test.tsx b/frontend/testing/unit/pages/ScansPhases.test.tsx
index 1c1046ec5..8bf970e00 100644
--- a/frontend/testing/unit/pages/ScansPhases.test.tsx
+++ b/frontend/testing/unit/pages/ScansPhases.test.tsx
@@ -4,6 +4,11 @@ import { vi, describe, it, expect, beforeEach, afterEach } from 'vitest';
 import Scans from '../../../src/pages/Scans';
 import { ToastProvider } from '../../../src/components/ToastContext'
 
+vi.mock('../../../src/components/ToastContext', () => ({
+  useToast: () => ({ addToast: vi.fn(), removeToast: vi.fn() }),
+  ToastProvider: ({ children }: any) => children,
+}))
+
 vi.mock('../../../src/api', () => ({
   API_BASE: 'http://localhost',
   deleteTask: vi.fn(),