Add zero-hop impulse advert. Closes #83.

frontend/src/api.ts

@@ -15,6 +15,7 @@ import type {
   MessagesAroundResponse,
   MigratePreferencesRequest,
   MigratePreferencesResponse,
+  RadioAdvertMode,
   RadioConfig,
   RadioConfigUpdate,
   RadioDiscoveryResponse,
@@ -95,9 +96,10 @@ export const api = {
       method: 'PUT',
       body: JSON.stringify({ private_key: privateKey }),
     }),
-  sendAdvertisement: () =>
+  sendAdvertisement: (mode: RadioAdvertMode = 'flood') =>
     fetchJson<{ status: string }>('/radio/advertise', {
       method: 'POST',
+      body: JSON.stringify({ mode }),
     }),
   discoverMesh: (target: RadioDiscoveryTarget) =>
     fetchJson<RadioDiscoveryResponse>('/radio/discover', {

frontend/src/components/SettingsModal.tsx

@@ -3,6 +3,7 @@ import type {
   AppSettings,
   AppSettingsUpdate,
   HealthStatus,
+  RadioAdvertMode,
   RadioConfig,
   RadioConfigUpdate,
   RadioDiscoveryResponse,
@@ -35,7 +36,7 @@ interface SettingsModalBaseProps {
   onReboot: () => Promise<void>;
   onDisconnect: () => Promise<void>;
   onReconnect: () => Promise<void>;
-  onAdvertise: () => Promise<void>;
+  onAdvertise: (mode: RadioAdvertMode) => Promise<void>;
   meshDiscovery: RadioDiscoveryResponse | null;
   meshDiscoveryLoadingTarget: RadioDiscoveryTarget | null;
   onDiscoverMesh: (target: RadioDiscoveryTarget) => Promise<void>;

frontend/src/components/settings/SettingsRadioSection.tsx

@@ -11,6 +11,7 @@ import type {
   AppSettings,
   AppSettingsUpdate,
   HealthStatus,
+  RadioAdvertMode,
   RadioConfig,
   RadioConfigUpdate,
   RadioDiscoveryResponse,
@@ -45,7 +46,7 @@ export function SettingsRadioSection({
   onReboot: () => Promise<void>;
   onDisconnect: () => Promise<void>;
   onReconnect: () => Promise<void>;
-  onAdvertise: () => Promise<void>;
+  onAdvertise: (mode: RadioAdvertMode) => Promise<void>;
   meshDiscovery: RadioDiscoveryResponse | null;
   meshDiscoveryLoadingTarget: RadioDiscoveryTarget | null;
   onDiscoverMesh: (target: RadioDiscoveryTarget) => Promise<void>;
@@ -82,7 +83,7 @@ export function SettingsRadioSection({
   const [floodError, setFloodError] = useState<string | null>(null);
 
   // Advertise state
-  const [advertising, setAdvertising] = useState(false);
+  const [advertisingMode, setAdvertisingMode] = useState<RadioAdvertMode | null>(null);
   const [discoverError, setDiscoverError] = useState<string | null>(null);
   const [connectionBusy, setConnectionBusy] = useState(false);
 
@@ -295,12 +296,12 @@ export function SettingsRadioSection({
     }
   };
 
-  const handleAdvertise = async () => {
-    setAdvertising(true);
+  const handleAdvertise = async (mode: RadioAdvertMode) => {
+    setAdvertisingMode(mode);
     try {
-      await onAdvertise();
+      await onAdvertise(mode);
     } finally {
-      setAdvertising(false);
+      setAdvertisingMode(null);
     }
   };
 
@@ -742,15 +743,25 @@ export function SettingsRadioSection({
       <div className="space-y-2">
         <Label>Send Advertisement</Label>
         <p className="text-xs text-muted-foreground">
-          Send a flood advertisement to announce your presence on the mesh network.
+          Flood adverts propagate through repeaters. Zero-hop adverts are local-only and use less
+          airtime.
         </p>
-        <Button
-          onClick={handleAdvertise}
-          disabled={advertising || !health?.radio_connected}
-          className="w-full bg-warning hover:bg-warning/90 text-warning-foreground"
-        >
-          {advertising ? 'Sending...' : 'Send Advertisement'}
-        </Button>
+        <div className="grid grid-cols-1 gap-2 sm:grid-cols-2">
+          <Button
+            onClick={() => handleAdvertise('flood')}
+            disabled={advertisingMode !== null || !health?.radio_connected}
+            className="w-full bg-warning hover:bg-warning/90 text-warning-foreground"
+          >
+            {advertisingMode === 'flood' ? 'Sending...' : 'Send Flood Advertisement'}
+          </Button>
+          <Button
+            onClick={() => handleAdvertise('zero_hop')}
+            disabled={advertisingMode !== null || !health?.radio_connected}
+            className="w-full"
+          >
+            {advertisingMode === 'zero_hop' ? 'Sending...' : 'Send Zero-Hop Advertisement'}
+          </Button>
+        </div>
         {!health?.radio_connected && (
           <p className="text-sm text-destructive">Radio not connected</p>
         )}

frontend/src/hooks/useRadioControl.ts

@@ -4,6 +4,7 @@ import { takePrefetchOrFetch } from '../prefetch';
 import { toast } from '../components/ui/sonner';
 import type {
   HealthStatus,
+  RadioAdvertMode,
   RadioConfig,
   RadioConfigUpdate,
   RadioDiscoveryResponse,
@@ -93,13 +94,14 @@ export function useRadioControl() {
     }
   }, [fetchConfig]);
 
-  const handleAdvertise = useCallback(async () => {
+  const handleAdvertise = useCallback(async (mode: RadioAdvertMode = 'flood') => {
     try {
-      await api.sendAdvertisement();
-      toast.success('Advertisement sent');
+      await api.sendAdvertisement(mode);
+      toast.success(mode === 'zero_hop' ? 'Zero-hop advertisement sent' : 'Advertisement sent');
     } catch (err) {
-      console.error('Failed to send advertisement:', err);
-      toast.error('Failed to send advertisement', {
+      const label = mode === 'zero_hop' ? 'zero-hop advertisement' : 'advertisement';
+      console.error(`Failed to send ${label}:`, err);
+      toast.error(`Failed to send ${label}`, {
         description: err instanceof Error ? err.message : 'Check radio connection',
       });
     }

frontend/src/test/api.test.ts

@@ -305,7 +305,7 @@ describe('fetchJson (via api methods)', () => {
       expect(options.method).toBe('DELETE');
     });
 
-    it('sends POST without body for sendAdvertisement', async () => {
+    it('sends POST with flood mode for sendAdvertisement', async () => {
       installMockFetch();
       mockFetch.mockResolvedValueOnce({
         ok: true,
@@ -317,7 +317,22 @@ describe('fetchJson (via api methods)', () => {
       const [url, options] = mockFetch.mock.calls[0];
       expect(url).toBe('/api/radio/advertise');
       expect(options.method).toBe('POST');
-      expect(options.body).toBeUndefined();
+      expect(options.body).toBe(JSON.stringify({ mode: 'flood' }));
+    });
+
+    it('sends POST with zero-hop mode for sendAdvertisement', async () => {
+      installMockFetch();
+      mockFetch.mockResolvedValueOnce({
+        ok: true,
+        json: () => Promise.resolve({ status: 'ok' }),
+      });
+
+      await api.sendAdvertisement('zero_hop');
+
+      const [url, options] = mockFetch.mock.calls[0];
+      expect(url).toBe('/api/radio/advertise');
+      expect(options.method).toBe('POST');
+      expect(options.body).toBe(JSON.stringify({ mode: 'zero_hop' }));
     });
   });
 

frontend/src/test/settingsModal.test.tsx

@@ -6,6 +6,7 @@ import type {
   AppSettings,
   AppSettingsUpdate,
   HealthStatus,
+  RadioAdvertMode,
   RadioConfig,
   RadioConfigUpdate,
   RadioDiscoveryResponse,
@@ -74,6 +75,7 @@ function renderModal(overrides?: {
   onReboot?: () => Promise<void>;
   onDisconnect?: () => Promise<void>;
   onReconnect?: () => Promise<void>;
+  onAdvertise?: (mode: RadioAdvertMode) => Promise<void>;
   meshDiscovery?: RadioDiscoveryResponse | null;
   meshDiscoveryLoadingTarget?: RadioDiscoveryTarget | null;
   onDiscoverMesh?: (target: RadioDiscoveryTarget) => Promise<void>;
@@ -93,6 +95,7 @@ function renderModal(overrides?: {
   const onReboot = overrides?.onReboot ?? vi.fn(async () => {});
   const onDisconnect = overrides?.onDisconnect ?? vi.fn(async () => {});
   const onReconnect = overrides?.onReconnect ?? vi.fn(async () => {});
+  const onAdvertise = overrides?.onAdvertise ?? vi.fn(async (_mode: RadioAdvertMode) => {});
   const onDiscoverMesh = overrides?.onDiscoverMesh ?? vi.fn(async () => {});
 
   const commonProps = {
@@ -108,7 +111,7 @@ function renderModal(overrides?: {
     onReboot,
     onDisconnect,
     onReconnect,
-    onAdvertise: vi.fn(async () => {}),
+    onAdvertise,
     meshDiscovery: overrides?.meshDiscovery ?? null,
     meshDiscoveryLoadingTarget: overrides?.meshDiscoveryLoadingTarget ?? null,
     onDiscoverMesh,
@@ -135,6 +138,7 @@ function renderModal(overrides?: {
     onReboot,
     onDisconnect,
     onReconnect,
+    onAdvertise,
     onDiscoverMesh,
     view,
   };
@@ -206,6 +210,22 @@ describe('SettingsModal', () => {
     expect(screen.getByText(/Configured radio contact capacity/i)).toBeInTheDocument();
   });
 
+  it('renders flood and zero-hop advert buttons and passes the selected mode', async () => {
+    const onAdvertise = vi.fn(async (_mode: RadioAdvertMode) => {});
+    renderModal({ onAdvertise });
+    openRadioSection();
+
+    fireEvent.click(screen.getByRole('button', { name: 'Send Flood Advertisement' }));
+    await waitFor(() => {
+      expect(onAdvertise).toHaveBeenCalledWith('flood');
+    });
+
+    fireEvent.click(screen.getByRole('button', { name: 'Send Zero-Hop Advertisement' }));
+    await waitFor(() => {
+      expect(onAdvertise).toHaveBeenCalledWith('zero_hop');
+    });
+  });
+
   it('shows radio-unavailable message when config is null', () => {
     renderModal({ config: null });
 

frontend/src/types.ts

@@ -45,6 +45,8 @@ export interface RadioDiscoveryResponse {
   results: RadioDiscoveryResult[];
 }
 
+export type RadioAdvertMode = 'flood' | 'zero_hop';
+
 export interface FanoutStatusEntry {
   name: string;
   type: string;