Use better behavior on disconnected radio and allow deeplinking into settings. Closes #66.

frontend/src/test/appFavorites.test.tsx

@@ -164,7 +164,10 @@ vi.mock('../components/ui/sonner', () => ({
 
 vi.mock('../utils/urlHash', () => ({
   parseHashConversation: () => null,
+  parseHashSettingsSection: () => null,
   updateUrlHash: vi.fn(),
+  updateSettingsHash: vi.fn(),
+  getSettingsHash: (section: string) => `#settings/${section}`,
   getMapFocusHash: () => '#map',
 }));
 

frontend/src/test/appStartupHash.test.tsx

@@ -90,7 +90,9 @@ vi.mock('../components/NewMessageModal', () => ({
 }));
 
 vi.mock('../components/SettingsModal', () => ({
-  SettingsModal: () => null,
+  SettingsModal: ({ desktopSection }: { desktopSection?: string }) => (
+    <div data-testid="settings-modal-section">{desktopSection ?? 'none'}</div>
+  ),
   SETTINGS_SECTION_ORDER: ['radio', 'local', 'database', 'bot'],
   SETTINGS_SECTION_LABELS: {
     radio: 'Radio',
@@ -293,4 +295,20 @@ describe('App startup hash resolution', () => {
     });
     expect(window.location.hash).toBe('');
   });
+
+  it('opens settings from a settings hash and falls back away from radio when disconnected', async () => {
+    window.location.hash = '#settings/radio';
+    mocks.api.getRadioConfig.mockRejectedValue(new Error('radio offline'));
+
+    render(<App />);
+
+    await waitFor(() => {
+      expect(screen.getByTestId('settings-modal-section')).toHaveTextContent('local');
+    });
+
+    for (const button of screen.getAllByRole('button', { name: 'Radio' })) {
+      expect(button).toBeDisabled();
+    }
+    expect(window.location.hash).toBe('#settings/local');
+  });
 });

frontend/src/test/settingsModal.test.tsx

@@ -63,6 +63,7 @@ const baseSettings: AppSettings = {
 };
 
 function renderModal(overrides?: {
+  config?: RadioConfig | null;
   appSettings?: AppSettings;
   health?: HealthStatus;
   onSaveAppSettings?: (update: AppSettingsUpdate) => Promise<void>;
@@ -97,7 +98,7 @@ function renderModal(overrides?: {
   const commonProps = {
     open: overrides?.open ?? true,
     pageMode: overrides?.pageMode,
-    config: baseConfig,
+    config: overrides?.config === undefined ? baseConfig : overrides.config,
     health: overrides?.health ?? baseHealth,
     appSettings: overrides?.appSettings ?? baseSettings,
     onClose,
@@ -205,6 +206,32 @@ describe('SettingsModal', () => {
     expect(screen.getByText(/Configured radio contact capacity/i)).toBeInTheDocument();
   });
 
+  it('keeps non-radio settings available when radio config is unavailable', () => {
+    renderModal({ config: null });
+
+    const radioToggle = screen.getByRole('button', { name: /Radio/i });
+    expect(radioToggle).toBeDisabled();
+
+    openLocalSection();
+    expect(screen.getByLabelText('Local label text')).toBeInTheDocument();
+
+    openDatabaseSection();
+    expect(screen.getByText('Delete Undecrypted Packets')).toBeInTheDocument();
+  });
+
+  it('shows a radio-unavailable message instead of blocking the whole settings page', () => {
+    renderModal({
+      config: null,
+      externalSidebarNav: true,
+      desktopSection: 'radio',
+    });
+
+    expect(
+      screen.getByText('Radio settings are unavailable until a radio connects.')
+    ).toBeInTheDocument();
+    expect(screen.queryByText('Loading configuration...')).not.toBeInTheDocument();
+  });
+
   it('shows cached radio firmware and capacity info under the connection status', () => {
     renderModal({
       health: {

frontend/src/test/urlHash.test.ts

@@ -8,6 +8,8 @@
 import { describe, it, expect, beforeEach, afterEach } from 'vitest';
 import {
   parseHashConversation,
+  parseHashSettingsSection,
+  getSettingsHash,
   getMapFocusHash,
   resolveChannelFromHashToken,
   resolveContactFromHashToken,
@@ -147,6 +149,34 @@ describe('parseHashConversation', () => {
   });
 });
 
+describe('settings URL hashes', () => {
+  let originalHash: string;
+
+  beforeEach(() => {
+    originalHash = window.location.hash;
+  });
+
+  afterEach(() => {
+    window.location.hash = originalHash;
+  });
+
+  it('parses a valid settings section hash', () => {
+    window.location.hash = '#settings/database';
+
+    expect(parseHashSettingsSection()).toBe('database');
+  });
+
+  it('returns null for an invalid settings section hash', () => {
+    window.location.hash = '#settings/not-a-section';
+
+    expect(parseHashSettingsSection()).toBeNull();
+  });
+
+  it('builds a stable settings hash', () => {
+    expect(getSettingsHash('local')).toBe('#settings/local');
+  });
+});
+
 describe('resolveChannelFromHashToken', () => {
   const channels: Channel[] = [
     {

frontend/src/test/useAppShell.test.ts

@@ -1,9 +1,19 @@
-import { act, renderHook } from '@testing-library/react';
-import { describe, expect, it } from 'vitest';
+import { act, renderHook, waitFor } from '@testing-library/react';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 
 import { useAppShell } from '../hooks/useAppShell';
 
 describe('useAppShell', () => {
+  let originalHash: string;
+
+  beforeEach(() => {
+    originalHash = window.location.hash;
+  });
+
+  afterEach(() => {
+    window.location.hash = originalHash;
+  });
+
   it('opens new-message modal and closes the sidebar', () => {
     const { result } = renderHook(() => useAppShell());
 
@@ -34,6 +44,55 @@ describe('useAppShell', () => {
     expect(result.current.showSettings).toBe(false);
   });
 
+  it('initializes settings mode from the URL hash', () => {
+    window.location.hash = '#settings/database';
+
+    const { result } = renderHook(() => useAppShell());
+
+    expect(result.current.showSettings).toBe(true);
+    expect(result.current.settingsSection).toBe('database');
+  });
+
+  it('syncs the selected settings section into the URL hash', async () => {
+    const { result } = renderHook(() => useAppShell());
+
+    act(() => {
+      result.current.handleToggleSettingsView();
+    });
+
+    await waitFor(() => {
+      expect(window.location.hash).toBe('#settings/radio');
+    });
+
+    act(() => {
+      result.current.setSettingsSection('fanout');
+    });
+
+    await waitFor(() => {
+      expect(window.location.hash).toBe('#settings/fanout');
+    });
+  });
+
+  it('restores the previous hash when settings close', async () => {
+    window.location.hash = '#channel/test/Public';
+
+    const { result } = renderHook(() => useAppShell());
+
+    act(() => {
+      result.current.handleToggleSettingsView();
+    });
+
+    await waitFor(() => {
+      expect(window.location.hash).toBe('#settings/radio');
+    });
+
+    act(() => {
+      result.current.handleCloseSettingsView();
+    });
+
+    expect(window.location.hash).toBe('#channel/test/Public');
+  });
+
   it('toggles the cracker shell without affecting sidebar state', () => {
     const { result } = renderHook(() => useAppShell());