fix: keep the pairing QR on screen while the Security tab checks the server

components/settings/__tests__/link-device-section.test.tsx

@@ -453,6 +453,20 @@ describe('AccountSecuritySettings link-device visibility', () => {
     expect(screen.queryByText('email_client.title')).toBeNull();
   });
 
+  it('mounts the linker only once the server probe has a verdict', () => {
+    // A layout guessed before the verdict remounted the linker afterwards and
+    // threw away a QR that was already showing.
+    useAuthStore.setState({ isAuthenticated: true, authMode: 'oauth', client: null });
+    useAccountSecurityStore.setState({ isStalwart: null, isProbing: false });
+    const { rerender } = render(<AccountSecuritySettings />);
+    expect(screen.queryByText('link_device.title')).toBeNull();
+    expect(screen.getByText('detecting')).toBeInTheDocument();
+
+    act(() => useAccountSecurityStore.setState({ isStalwart: false }));
+    rerender(<AccountSecuritySettings />);
+    expect(screen.getByText('link_device.title')).toBeInTheDocument();
+  });
+
   it('hides the linker in Bulwark Lite', () => {
     mocks.lite.value = true;
     useAccountSecurityStore.setState({ isStalwart: false, isProbing: false });

components/settings/account-security-settings.tsx

@@ -1451,7 +1451,10 @@ export function AccountSecuritySettings() {
     }
   }, [isAuthenticated, client, isStalwart, probe, fetchAll, fetchAuthInfo, isOAuth, fetchPublicKeys, fetchCryptoInfo]);
 
-  if (isProbing) {
+  // Until the probe has a verdict, show the spinner instead of guessing a
+  // layout: switching layouts remounts every section below, which threw away
+  // a pairing QR that was already on screen.
+  if (isProbing || (isStalwart === null && isAuthenticated)) {
     return (
       <SettingsSection title={t('title')} description={t('description')}>
         <div className="flex items-center gap-2 py-4">