Fix removal of stale Tailscale devices (#161084)

Co-authored-by: Stan Cope <976785+scopey@users.noreply.github.com>
Co-authored-by: Abílio Costa <abmantis@users.noreply.github.com>

homeassistant/components/tailscale/coordinator.py

@@ -8,6 +8,7 @@ from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import CONF_API_KEY
 from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import ConfigEntryAuthFailed
+from homeassistant.helpers import device_registry as dr
 from homeassistant.helpers.aiohttp_client import async_get_clientsession
 from homeassistant.helpers.update_coordinator import DataUpdateCoordinator
 
@@ -27,6 +28,7 @@ class TailscaleDataUpdateCoordinator(DataUpdateCoordinator[dict[str, Device]]):
             api_key=config_entry.data[CONF_API_KEY],
             tailnet=config_entry.data[CONF_TAILNET],
         )
+        self.previous_devices: set[str] = set()
 
         super().__init__(
             hass,
@@ -37,8 +39,32 @@ class TailscaleDataUpdateCoordinator(DataUpdateCoordinator[dict[str, Device]]):
         )
 
     async def _async_update_data(self) -> dict[str, Device]:
-        """Fetch devices from Tailscale."""
+        """Fetch devices from Tailscale and remove stale devices from HA."""
         try:
-            return await self.tailscale.devices()
+            devices = await self.tailscale.devices()
         except TailscaleAuthenticationError as err:
             raise ConfigEntryAuthFailed from err
+
+        # Get current device IDs
+        current_device_ids = set(devices.keys())
+
+        # Find devices that were removed from Tailscale
+        if self.previous_devices:
+            stale_device_ids = self.previous_devices - current_device_ids
+            if stale_device_ids:
+                await self._remove_stale_devices(stale_device_ids)
+
+        # Update previous devices set for next comparison
+        self.previous_devices = current_device_ids
+
+        return devices
+
+    async def _remove_stale_devices(self, stale_device_ids: set[str]) -> None:
+        """Remove devices that no longer exist in Tailscale."""
+        device_registry = dr.async_get(self.hass)
+
+        for device_id in stale_device_ids:
+            device = device_registry.async_get_device(identifiers={(DOMAIN, device_id)})
+            if device:
+                LOGGER.debug("Removing stale device: %s", device_id)
+                device_registry.async_remove_device(device.id)

tests/components/tailscale/test_coordinator.py

@@ -0,0 +1,76 @@
+"""Tests for the Tailscale coordinator."""
+
+from datetime import timedelta
+from unittest.mock import MagicMock
+
+from freezegun.api import FrozenDateTimeFactory
+
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers import device_registry as dr
+
+from tests.common import MockConfigEntry
+
+
+async def test_remove_stale_devices(
+    hass: HomeAssistant,
+    init_integration: MockConfigEntry,
+    mock_tailscale: MagicMock,
+    device_registry: dr.DeviceRegistry,
+    freezer: FrozenDateTimeFactory,
+) -> None:
+    """Test that devices removed from Tailscale are removed from device registry."""
+    # Verify initial devices exist (should be 3 from fixture)
+    devices = dr.async_entries_for_config_entry(
+        device_registry, init_integration.entry_id
+    )
+    assert len(devices) == 3
+
+    # Store device IDs for later verification
+    device_ids = [list(device.identifiers)[0][1] for device in devices]
+    assert "123456" in device_ids
+    assert "123457" in device_ids
+    assert "123458" in device_ids
+
+    # Simulate device removal in Tailscale (only device 123456 remains)
+    # Get the original device data from the mock
+    original_devices = mock_tailscale.devices.return_value
+    mock_tailscale.devices.return_value = {"123456": original_devices["123456"]}
+
+    # Trigger natural refresh by advancing time
+    freezer.tick(timedelta(seconds=60))
+    await hass.async_block_till_done()
+
+    # Verify devices 123457 and 123458 were removed
+    remaining_devices = dr.async_entries_for_config_entry(
+        device_registry, init_integration.entry_id
+    )
+    assert len(remaining_devices) == 1
+
+    remaining_device = remaining_devices[0]
+    remaining_id = list(remaining_device.identifiers)[0][1]
+    assert remaining_id == "123456"
+    assert remaining_device.name == "frencks-iphone"
+
+
+async def test_no_devices_removed_when_all_present(
+    hass: HomeAssistant,
+    init_integration: MockConfigEntry,
+    device_registry: dr.DeviceRegistry,
+    freezer: FrozenDateTimeFactory,
+) -> None:
+    """Test that no devices are removed when all Tailscale devices still exist."""
+    # Verify initial devices exist (should be 3 from fixture)
+    initial_devices = dr.async_entries_for_config_entry(
+        device_registry, init_integration.entry_id
+    )
+    assert len(initial_devices) == 3
+
+    # Trigger natural refresh (devices unchanged)
+    freezer.tick(timedelta(seconds=60))
+    await hass.async_block_till_done()
+
+    # Verify no devices were removed
+    final_devices = dr.async_entries_for_config_entry(
+        device_registry, init_integration.entry_id
+    )
+    assert len(final_devices) == 3