Open the connector a ?connector= link names on the mounted page

The Connectors page read ?connector= only when it mounted, so the
Reconnect link in the global toast did nothing while the page was
already open.

frontend/src/settings/Connectors.test.tsx

@@ -2,7 +2,7 @@ import { configureStore } from '@reduxjs/toolkit';
 import { act } from 'react';
 import { createRoot, type Root } from 'react-dom/client';
 import { Provider } from 'react-redux';
-import { MemoryRouter } from 'react-router-dom';
+import { Link, MemoryRouter } from 'react-router-dom';
 
 vi.mock('react-i18next', () => ({
   useTranslation: () => ({
@@ -144,6 +144,10 @@ describe('Connectors page', () => {
       root.render(
         <Provider store={store}>
           <MemoryRouter initialEntries={[path]}>
+            <Link
+              data-testid="reconnect-link"
+              to="/settings/connectors?connector=google_drive"
+            />
             <Connectors />
           </MemoryRouter>
         </Provider>,
@@ -378,6 +382,18 @@ describe('Connectors page', () => {
     );
   });
 
+  it('opens the page a ?connector= link names while already on the list', async () => {
+    await render();
+    expect(document.body.querySelector('[role="dialog"]')).toBeNull();
+    await act(async () =>
+      container
+        .querySelector<HTMLAnchorElement>('[data-testid="reconnect-link"]')!
+        .click(),
+    );
+    const dialog = document.body.querySelector('[role="dialog"]');
+    expect(dialog?.textContent).toContain('Google Drive');
+  });
+
   it('shows a retry when the catalog fails to load', async () => {
     service.getCatalog.mockResolvedValue({ success: false });
     await render();

frontend/src/settings/Connectors.tsx

@@ -82,9 +82,15 @@ export default function Connectors() {
   const [filter, setFilter] = useState<Filter>(
     initialFilter && FILTERS.includes(initialFilter) ? initialFilter : 'all',
   );
-  const [openKey, setOpenKey] = useState<string | null>(
-    searchParams.get('connector'),
-  );
+  const connectorParam = searchParams.get('connector');
+  const [openKey, setOpenKey] = useState<string | null>(connectorParam);
+  // A `?connector=` link followed while this page is already open (the
+  // global Reconnect toast) changes only the search: open what it names.
+  const [seenConnectorParam, setSeenConnectorParam] = useState(connectorParam);
+  if (connectorParam !== seenConnectorParam) {
+    setSeenConnectorParam(connectorParam);
+    if (connectorParam) setOpenKey(connectorParam);
+  }
   const { launch, modals } = useConnectorLauncher();
 
   useEffect(() => {