perf(web): make mileage exports cancellable

vehicle-data-platform/apps/web/src/v2/pages/StatisticsPage.test.tsx

@@ -126,5 +126,54 @@ test('exports the full fleet mileage with one paginated query instead of VIN bat
   expect(exportMileageCall.get('vins')).toBeNull();
   expect(exportMileageCall.get('vehicleScope')).toBe('bound');
   expect(exportMocks.downloadMileageWorkbook.mock.calls[0][0].vehicles).toHaveLength(1);
+  expect(mocks.vehicleCoverage.mock.calls[mocks.vehicleCoverage.mock.calls.length - 1][1]).toBeInstanceOf(AbortSignal);
+  expect(mocks.dailyMileage.mock.calls[mocks.dailyMileage.mock.calls.length - 1][1]).toBeInstanceOf(AbortSignal);
+  expect(exportMocks.downloadMileageWorkbook.mock.calls[0][1]).toBeInstanceOf(AbortSignal);
   expect(screen.getByText(/已导出 1 辆车/)).toBeInTheDocument();
 });
+
+test('shows export progress and lets the user cancel the active request', async () => {
+  prepareData();
+  let exportSignal: AbortSignal | undefined;
+  mocks.vehicleCoverage.mockImplementation((params: URLSearchParams, signal?: AbortSignal) => {
+    if (params.get('limit') !== String(2_000)) {
+      return Promise.resolve({ items: [{ vin: 'LTEST000000000001', plate: '粤A12345' }], total: 1, limit: 20, offset: 0 });
+    }
+    exportSignal = signal;
+    return new Promise((_resolve, reject) => {
+      signal?.addEventListener('abort', () => reject(new DOMException('cancelled', 'AbortError')), { once: true });
+    });
+  });
+  renderPage('/statistics?dateFrom=2026-07-13&dateTo=2026-07-14');
+  await waitFor(() => expect(screen.getByRole('button', { name: '导出 Excel' })).toBeEnabled());
+
+  fireEvent.click(screen.getByRole('button', { name: '导出 Excel' }));
+  expect(await screen.findByRole('progressbar', { name: '正在读取车辆档案' })).toBeInTheDocument();
+  expect(screen.getByRole('button', { name: '取消导出' })).toBeEnabled();
+  fireEvent.click(screen.getByRole('button', { name: '取消导出' }));
+
+  await waitFor(() => expect(exportSignal?.aborted).toBe(true));
+  expect(await screen.findByText(/已取消导出/)).toBeInTheDocument();
+  expect(exportMocks.downloadMileageWorkbook).not.toHaveBeenCalled();
+});
+
+test('aborts an active export when the mileage route unmounts', async () => {
+  prepareData();
+  let exportSignal: AbortSignal | undefined;
+  mocks.vehicleCoverage.mockImplementation((params: URLSearchParams, signal?: AbortSignal) => {
+    if (params.get('limit') !== String(2_000)) {
+      return Promise.resolve({ items: [{ vin: 'LTEST000000000001', plate: '粤A12345' }], total: 1, limit: 20, offset: 0 });
+    }
+    exportSignal = signal;
+    return new Promise(() => undefined);
+  });
+  const view = renderPage('/statistics?dateFrom=2026-07-13&dateTo=2026-07-14');
+  await waitFor(() => expect(screen.getByRole('button', { name: '导出 Excel' })).toBeEnabled());
+  fireEvent.click(screen.getByRole('button', { name: '导出 Excel' }));
+  expect(await screen.findByRole('progressbar', { name: '正在读取车辆档案' })).toBeInTheDocument();
+
+  view.unmount();
+
+  expect(exportSignal?.aborted).toBe(true);
+  expect(exportMocks.downloadMileageWorkbook).not.toHaveBeenCalled();
+});