Multi-ack. Closes #81.

AGENTS.md

@@ -307,8 +307,8 @@ All endpoints are prefixed with `/api` (e.g., `/api/health`).
 |--------|----------|-------------|
 | GET | `/api/health` | Connection status, fanout statuses, bots_disabled flag |
 | GET | `/api/debug` | Support snapshot: recent logs, live radio probe, contact/channel drift audit, and running version/git info |
-| GET | `/api/radio/config` | Radio configuration, including `path_hash_mode`, `path_hash_mode_supported`, and whether adverts include current node location |
-| PATCH | `/api/radio/config` | Update name, location, advert-location on/off, radio params, and `path_hash_mode` when supported |
+| GET | `/api/radio/config` | Radio configuration, including `path_hash_mode`, `path_hash_mode_supported`, advert-location on/off, and `multi_acks_enabled` |
+| PATCH | `/api/radio/config` | Update name, location, advert-location on/off, `multi_acks_enabled`, radio params, and `path_hash_mode` when supported |
 | PUT | `/api/radio/private-key` | Import private key to radio |
 | POST | `/api/radio/advertise` | Send advertisement (`mode`: `flood` or `zero_hop`, default `flood`) |
 | POST | `/api/radio/discover` | Run a short mesh discovery sweep for nearby repeaters/sensors |

app/AGENTS.md

@@ -169,8 +169,8 @@ app/
 - `GET /debug` — support snapshot with recent logs, live radio probe, slot/contact audits, and version/git info
 
 ### Radio
-- `GET /radio/config` — includes `path_hash_mode`, `path_hash_mode_supported`, and advert-location on/off
-- `PATCH /radio/config` — may update `path_hash_mode` (`0..2`) when firmware supports it
+- `GET /radio/config` — includes `path_hash_mode`, `path_hash_mode_supported`, advert-location on/off, and `multi_acks_enabled`
+- `PATCH /radio/config` — may update `path_hash_mode` (`0..2`) when firmware supports it, and `multi_acks_enabled`
 - `PUT /radio/private-key`
 - `POST /radio/advertise` — manual advert send; request body may set `mode` to `flood` or `zero_hop` (defaults to `flood`)
 - `POST /radio/discover` — short mesh discovery sweep for nearby repeaters/sensors

app/routers/debug.py

@@ -78,6 +78,7 @@ class DebugChannelAudit(BaseModel):
 class DebugRadioProbe(BaseModel):
     performed: bool
     errors: list[str] = Field(default_factory=list)
+    multi_acks_enabled: bool | None = None
     self_info: dict[str, Any] | None = None
     device_info: dict[str, Any] | None = None
     stats_core: dict[str, Any] | None = None
@@ -234,6 +235,9 @@ async def _probe_radio() -> DebugRadioProbe:
             return DebugRadioProbe(
                 performed=True,
                 errors=errors,
+                multi_acks_enabled=bool(mc.self_info.get("multi_acks", 0))
+                if mc.self_info is not None
+                else None,
                 self_info=dict(mc.self_info or {}),
                 device_info=device_info,
                 stats_core=stats_core,

app/routers/radio.py

@@ -81,6 +81,10 @@ class RadioConfigResponse(BaseModel):
         default="current",
         description="Whether adverts include the node's current location state",
     )
+    multi_acks_enabled: bool = Field(
+        default=False,
+        description="Whether the radio sends an extra direct ACK transmission",
+    )
 
 
 class RadioConfigUpdate(BaseModel):
@@ -99,6 +103,10 @@ class RadioConfigUpdate(BaseModel):
         default=None,
         description="Whether adverts include the node's current location state",
     )
+    multi_acks_enabled: bool | None = Field(
+        default=None,
+        description="Whether the radio sends an extra direct ACK transmission",
+    )
 
 
 class PrivateKeyUpdate(BaseModel):
@@ -222,6 +230,7 @@ async def get_radio_config() -> RadioConfigResponse:
         path_hash_mode=radio_manager.path_hash_mode,
         path_hash_mode_supported=radio_manager.path_hash_mode_supported,
         advert_location_source=advert_location_source,
+        multi_acks_enabled=bool(info.get("multi_acks", 0)),
     )
 
 

app/services/radio_commands.py

@@ -44,6 +44,13 @@ async def apply_radio_config_update(
                 f"Failed to set advert location policy: {result.payload}"
             )
 
+    if update.multi_acks_enabled is not None:
+        multi_acks = 1 if update.multi_acks_enabled else 0
+        logger.info("Setting multi ACKs to %d", multi_acks)
+        result = await mc.commands.set_multi_acks(multi_acks)
+        if result is not None and result.type == EventType.ERROR:
+            raise RadioCommandRejectedError(f"Failed to set multi ACKs: {result.payload}")
+
     if update.name is not None:
         logger.info("Setting radio name to %s", update.name)
         await mc.commands.set_name(update.name)

frontend/AGENTS.md

@@ -250,6 +250,7 @@ High-level state is delegated to hooks:
 ### Radio settings behavior
 
 - `SettingsRadioSection.tsx` surfaces `path_hash_mode` only when `config.path_hash_mode_supported` is true.
+- `SettingsRadioSection.tsx` also exposes `multi_acks_enabled` as a checkbox for the radio's extra direct-ACK transmission behavior.
 - Advert-location control is intentionally only `off` vs `include node location`. Companion-radio firmware does not reliably distinguish saved coordinates from live GPS in this path.
 - The advert action is mode-aware: the radio settings section exposes both flood and zero-hop manual advert buttons, both routed through the same `onAdvertise(mode)` seam.
 - Mesh discovery in the radio section is limited to node classes that currently answer discovery control-data requests in firmware: repeaters and sensors.

frontend/src/components/settings/SettingsRadioSection.tsx

@@ -5,6 +5,7 @@ import { Label } from '../ui/label';
 import { Button } from '../ui/button';
 import { Separator } from '../ui/separator';
 import { toast } from '../ui/sonner';
+import { Checkbox } from '../ui/checkbox';
 import { RADIO_PRESETS } from '../../utils/radioPresets';
 import { stripRegionScopePrefix } from '../../utils/regionScope';
 import type {
@@ -64,6 +65,7 @@ export function SettingsRadioSection({
   const [cr, setCr] = useState('');
   const [pathHashMode, setPathHashMode] = useState('0');
   const [advertLocationSource, setAdvertLocationSource] = useState<'off' | 'current'>('current');
+  const [multiAcksEnabled, setMultiAcksEnabled] = useState(false);
   const [gettingLocation, setGettingLocation] = useState(false);
   const [busy, setBusy] = useState(false);
   const [rebooting, setRebooting] = useState(false);
@@ -98,6 +100,7 @@ export function SettingsRadioSection({
     setCr(String(config.radio.cr));
     setPathHashMode(String(config.path_hash_mode));
     setAdvertLocationSource(config.advert_location_source ?? 'current');
+    setMultiAcksEnabled(config.multi_acks_enabled ?? false);
   }, [config]);
 
   useEffect(() => {
@@ -190,6 +193,9 @@ export function SettingsRadioSection({
       ...(advertLocationSource !== (config.advert_location_source ?? 'current')
         ? { advert_location_source: advertLocationSource }
         : {}),
+      ...(multiAcksEnabled !== (config.multi_acks_enabled ?? false)
+        ? { multi_acks_enabled: multiAcksEnabled }
+        : {}),
       radio: {
         freq: parsedFreq,
         bw: parsedBw,
@@ -579,6 +585,24 @@ export function SettingsRadioSection({
             library.
           </p>
         </div>
+        <div className="space-y-2">
+          <div className="flex items-start gap-3 rounded-md border border-border/60 p-3">
+            <Checkbox
+              id="multi-acks-enabled"
+              checked={multiAcksEnabled}
+              onCheckedChange={(checked) => setMultiAcksEnabled(checked === true)}
+              className="mt-0.5"
+            />
+            <div className="space-y-1">
+              <Label htmlFor="multi-acks-enabled">Extra Direct ACK Transmission</Label>
+              <p className="text-xs text-muted-foreground">
+                When enabled, the radio sends one extra direct ACK transmission before the normal
+                ACK for received direct messages. This is a firmware-level receive behavior, not a
+                RemoteTerm retry setting.
+              </p>
+            </div>
+          </div>
+        </div>
       </div>
 
       {config.path_hash_mode_supported && (

frontend/src/test/settingsModal.test.tsx

@@ -37,6 +37,7 @@ const baseConfig: RadioConfig = {
   path_hash_mode: 0,
   path_hash_mode_supported: false,
   advert_location_source: 'current',
+  multi_acks_enabled: false,
 };
 
 const baseHealth: HealthStatus = {
@@ -332,6 +333,18 @@ describe('SettingsModal', () => {
     });
   });
 
+  it('saves multi-acks through radio config save', async () => {
+    const { onSave } = renderModal();
+    openRadioSection();
+
+    fireEvent.click(screen.getByLabelText('Extra Direct ACK Transmission'));
+    fireEvent.click(screen.getByRole('button', { name: 'Save' }));
+
+    await waitFor(() => {
+      expect(onSave).toHaveBeenCalledWith(expect.objectContaining({ multi_acks_enabled: true }));
+    });
+  });
+
   it('saves changed max contacts value through onSaveAppSettings', async () => {
     const { onSaveAppSettings } = renderModal();
     openRadioSection();

frontend/src/types.ts

@@ -16,6 +16,7 @@ export interface RadioConfig {
   path_hash_mode: number;
   path_hash_mode_supported: boolean;
   advert_location_source?: 'off' | 'current';
+  multi_acks_enabled?: boolean;
 }
 
 export interface RadioConfigUpdate {
@@ -26,6 +27,7 @@ export interface RadioConfigUpdate {
   radio?: RadioSettings;
   path_hash_mode?: number;
   advert_location_source?: 'off' | 'current';
+  multi_acks_enabled?: boolean;
 }
 
 export type RadioDiscoveryTarget = 'repeaters' | 'sensors' | 'all';

tests/test_radio_commands_service.py

@@ -33,6 +33,7 @@ def _mock_meshcore_with_info():
     mc.commands.set_radio = AsyncMock()
     mc.commands.set_path_hash_mode = AsyncMock(return_value=_radio_result())
     mc.commands.set_advert_loc_policy = AsyncMock(return_value=_radio_result())
+    mc.commands.set_multi_acks = AsyncMock(return_value=_radio_result())
     mc.commands.send_appstart = AsyncMock()
     mc.commands.import_private_key = AsyncMock(return_value=_radio_result())
     return mc
@@ -84,6 +85,39 @@ class TestApplyRadioConfigUpdate:
         mc.commands.set_advert_loc_policy.assert_awaited_once_with(1)
         mc.commands.send_appstart.assert_awaited_once()
 
+    @pytest.mark.asyncio
+    async def test_updates_multi_acks_enabled(self):
+        mc = _mock_meshcore_with_info()
+
+        await apply_radio_config_update(
+            mc,
+            RadioConfigUpdate(multi_acks_enabled=True),
+            path_hash_mode_supported=True,
+            set_path_hash_mode=MagicMock(),
+            sync_radio_time_fn=AsyncMock(),
+        )
+
+        mc.commands.set_multi_acks.assert_awaited_once_with(1)
+        mc.commands.send_appstart.assert_awaited_once()
+
+    @pytest.mark.asyncio
+    async def test_raises_when_radio_rejects_multi_acks(self):
+        mc = _mock_meshcore_with_info()
+        mc.commands.set_multi_acks = AsyncMock(
+            return_value=_radio_result(EventType.ERROR, {"error": "nope"})
+        )
+
+        with pytest.raises(RadioCommandRejectedError):
+            await apply_radio_config_update(
+                mc,
+                RadioConfigUpdate(multi_acks_enabled=False),
+                path_hash_mode_supported=True,
+                set_path_hash_mode=MagicMock(),
+                sync_radio_time_fn=AsyncMock(),
+            )
+
+        mc.commands.send_appstart.assert_not_awaited()
+
     @pytest.mark.asyncio
     async def test_raises_when_radio_rejects_advert_location_source(self):
         mc = _mock_meshcore_with_info()

tests/test_radio_router.py

@@ -75,6 +75,7 @@ def _mock_meshcore_with_info():
         "radio_sf": 7,
         "radio_cr": 5,
         "adv_loc_policy": 2,
+        "multi_acks": 0,
     }
     mc.commands = MagicMock()
     mc.commands.set_name = AsyncMock()
@@ -82,6 +83,7 @@ def _mock_meshcore_with_info():
     mc.commands.set_tx_power = AsyncMock()
     mc.commands.set_radio = AsyncMock()
     mc.commands.set_advert_loc_policy = AsyncMock(return_value=_radio_result())
+    mc.commands.set_multi_acks = AsyncMock(return_value=_radio_result())
     mc.commands.send_appstart = AsyncMock()
     mc.commands.import_private_key = AsyncMock(return_value=_radio_result())
     mc.commands.send_node_discover_req = AsyncMock(return_value=_radio_result())
@@ -104,6 +106,17 @@ class TestGetRadioConfig:
         assert response.radio.freq == 910.525
         assert response.radio.cr == 5
         assert response.advert_location_source == "current"
+        assert response.multi_acks_enabled is False
+
+    @pytest.mark.asyncio
+    async def test_maps_multi_acks_to_response(self):
+        mc = _mock_meshcore_with_info()
+        mc.self_info["multi_acks"] = 1
+
+        with patch("app.routers.radio.require_connected", return_value=mc):
+            response = await get_radio_config()
+
+        assert response.multi_acks_enabled is True
 
     @pytest.mark.asyncio
     async def test_maps_any_nonzero_advert_location_policy_to_current(self):
@@ -172,6 +185,7 @@ class TestUpdateRadioConfig:
             path_hash_mode=0,
             path_hash_mode_supported=False,
             advert_location_source="current",
+            multi_acks_enabled=False,
         )
 
         with (
@@ -187,6 +201,36 @@ class TestUpdateRadioConfig:
         mc.commands.set_advert_loc_policy.assert_awaited_once_with(1)
         assert result == expected
 
+    @pytest.mark.asyncio
+    async def test_updates_multi_acks_enabled(self):
+        mc = _mock_meshcore_with_info()
+        expected = RadioConfigResponse(
+            public_key="aa" * 32,
+            name="NodeA",
+            lat=10.0,
+            lon=20.0,
+            tx_power=17,
+            max_tx_power=22,
+            radio=RadioSettings(freq=910.525, bw=62.5, sf=7, cr=5),
+            path_hash_mode=0,
+            path_hash_mode_supported=False,
+            advert_location_source="current",
+            multi_acks_enabled=True,
+        )
+
+        with (
+            patch("app.routers.radio.require_connected", return_value=mc),
+            patch.object(radio_manager, "_meshcore", mc),
+            patch("app.routers.radio.sync_radio_time", new_callable=AsyncMock),
+            patch(
+                "app.routers.radio.get_radio_config", new_callable=AsyncMock, return_value=expected
+            ),
+        ):
+            result = await update_radio_config(RadioConfigUpdate(multi_acks_enabled=True))
+
+        mc.commands.set_multi_acks.assert_awaited_once_with(1)
+        assert result == expected
+
     def test_model_rejects_negative_path_hash_mode(self):
         with pytest.raises(ValidationError):
             RadioConfigUpdate(path_hash_mode=-1)