fix: resolve race condition in dashboard counts display

The DashboardViewModel was using non-atomic state updates
(_uiState.value = _uiState.value.copy(...)) which caused a race
condition when two coroutines tried to update state concurrently.

When loading charges and drives counts in parallel:
1. Both coroutines read the state snapshot
2. Both do async work (API calls)
3. Each writes back with .copy() - second write overwrites first

With large datasets, API calls take longer, making this race window
much larger - explaining why users with many drives/charges saw
missing totals on the dashboard.

Fixed by using MutableStateFlow.update{} throughout the ViewModel,
which provides atomic state updates. Also updated tests to match
the current ViewModel API (CarStatusWithUnits, GeocodingRepository).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Software Versions**: Tap the external link icon next to any version to view release notes on NotATeslaApp
 
 ### Fixed
+- **Dashboard**: Fix race condition where drive/charge counts could fail to display for users with large datasets
 - **Software Versions**: Show all software updates instead of only the first 100
 
 ## [0.6.1] - 2025-12-22

app/src/main/java/com/matedroid/ui/screens/dashboard/DashboardViewModel.kt

@@ -15,6 +15,7 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import javax.inject.Inject
@@ -75,24 +76,28 @@ class DashboardViewModel @Inject constructor(
 
     fun loadCars() {
         viewModelScope.launch {
-            _uiState.value = _uiState.value.copy(isLoading = true, error = null)
+            _uiState.update { it.copy(isLoading = true, error = null) }
 
             when (val result = repository.getCars()) {
                 is ApiResult.Success -> {
                     val cars = result.data
                     val selectedCarId = cars.firstOrNull()?.carId
-                    _uiState.value = _uiState.value.copy(
-                        isLoading = false,
-                        cars = cars,
-                        selectedCarId = selectedCarId
-                    )
+                    _uiState.update {
+                        it.copy(
+                            isLoading = false,
+                            cars = cars,
+                            selectedCarId = selectedCarId
+                        )
+                    }
                     selectedCarId?.let { loadCarStatus(it) }
                 }
                 is ApiResult.Error -> {
-                    _uiState.value = _uiState.value.copy(
-                        isLoading = false,
-                        error = result.message
-                    )
+                    _uiState.update {
+                        it.copy(
+                            isLoading = false,
+                            error = result.message
+                        )
+                    }
                 }
             }
         }
@@ -101,40 +106,42 @@ class DashboardViewModel @Inject constructor(
     fun selectCar(carId: Int) {
         // Reset state when switching cars
         lastGeocodedLocation = null
-        _uiState.value = _uiState.value.copy(
-            selectedCarId = carId,
-            carStatus = null,
-            resolvedAddress = null,
-            totalCharges = null,
-            totalDrives = null
-        )
+        _uiState.update {
+            it.copy(
+                selectedCarId = carId,
+                carStatus = null,
+                resolvedAddress = null,
+                totalCharges = null,
+                totalDrives = null
+            )
+        }
         loadCarStatus(carId)
     }
 
     fun refresh() {
         val carId = _uiState.value.selectedCarId ?: return
         viewModelScope.launch {
-            _uiState.value = _uiState.value.copy(isRefreshing = true, error = null)
+            _uiState.update { it.copy(isRefreshing = true, error = null) }
 
             // Fetch car status directly (not via loadCarStatus which launches separate coroutine)
             when (val result = repository.getCarStatus(carId)) {
                 is ApiResult.Success -> {
                     val status = result.data.status
-                    _uiState.value = _uiState.value.copy(
-                        carStatus = status,
-                        units = result.data.units,
-                        error = null
-                    )
+                    _uiState.update {
+                        it.copy(
+                            carStatus = status,
+                            units = result.data.units,
+                            error = null
+                        )
+                    }
                     fetchAddressIfNeeded(status)
                 }
                 is ApiResult.Error -> {
-                    _uiState.value = _uiState.value.copy(
-                        error = result.message
-                    )
+                    _uiState.update { it.copy(error = result.message) }
                 }
             }
 
-            _uiState.value = _uiState.value.copy(isRefreshing = false)
+            _uiState.update { it.copy(isRefreshing = false) }
         }
     }
 
@@ -143,18 +150,18 @@ class DashboardViewModel @Inject constructor(
             when (val result = repository.getCarStatus(carId)) {
                 is ApiResult.Success -> {
                     val status = result.data.status
-                    _uiState.value = _uiState.value.copy(
-                        carStatus = status,
-                        units = result.data.units,
-                        error = null
-                    )
+                    _uiState.update {
+                        it.copy(
+                            carStatus = status,
+                            units = result.data.units,
+                            error = null
+                        )
+                    }
                     // Fetch address if no geofence but coordinates are available
                     fetchAddressIfNeeded(status)
                 }
                 is ApiResult.Error -> {
-                    _uiState.value = _uiState.value.copy(
-                        error = result.message
-                    )
+                    _uiState.update { it.copy(error = result.message) }
                 }
             }
         }
@@ -167,7 +174,7 @@ class DashboardViewModel @Inject constructor(
             // Load charges count
             when (val result = repository.getCharges(carId, null, null)) {
                 is ApiResult.Success -> {
-                    _uiState.value = _uiState.value.copy(totalCharges = result.data.size)
+                    _uiState.update { it.copy(totalCharges = result.data.size) }
                 }
                 is ApiResult.Error -> { /* ignore */ }
             }
@@ -176,7 +183,7 @@ class DashboardViewModel @Inject constructor(
             // Load drives count
             when (val result = repository.getDrives(carId, null, null)) {
                 is ApiResult.Success -> {
-                    _uiState.value = _uiState.value.copy(totalDrives = result.data.size)
+                    _uiState.update { it.copy(totalDrives = result.data.size) }
                 }
                 is ApiResult.Error -> { /* ignore */ }
             }
@@ -202,12 +209,12 @@ class DashboardViewModel @Inject constructor(
             viewModelScope.launch {
                 val address = geocodingRepository.reverseGeocode(lat, lon)
                 if (address != null) {
-                    _uiState.value = _uiState.value.copy(resolvedAddress = address)
+                    _uiState.update { it.copy(resolvedAddress = address) }
                 }
             }
         } else if (hasGeofence) {
             // Clear resolved address if geofence is available
-            _uiState.value = _uiState.value.copy(resolvedAddress = null)
+            _uiState.update { it.copy(resolvedAddress = null) }
             lastGeocodedLocation = null
         }
     }
@@ -220,10 +227,12 @@ class DashboardViewModel @Inject constructor(
                 when (val result = repository.getCarStatus(carId)) {
                     is ApiResult.Success -> {
                         val status = result.data.status
-                        _uiState.value = _uiState.value.copy(
-                            carStatus = status,
-                            units = result.data.units
-                        )
+                        _uiState.update {
+                            it.copy(
+                                carStatus = status,
+                                units = result.data.units
+                            )
+                        }
                         // Update address if location changed
                         fetchAddressIfNeeded(status)
                     }
@@ -236,6 +245,6 @@ class DashboardViewModel @Inject constructor(
     }
 
     fun clearError() {
-        _uiState.value = _uiState.value.copy(error = null)
+        _uiState.update { it.copy(error = null) }
     }
 }

app/src/test/java/com/matedroid/ui/screens/dashboard/DashboardViewModelTest.kt

@@ -5,7 +5,10 @@ import com.matedroid.data.api.models.CarData
 import com.matedroid.data.api.models.CarStatus
 import com.matedroid.data.api.models.CarStatusDetails
 import com.matedroid.data.api.models.ChargingDetails
+import com.matedroid.data.api.models.Units
 import com.matedroid.data.repository.ApiResult
+import com.matedroid.data.repository.CarStatusWithUnits
+import com.matedroid.data.repository.GeocodingRepository
 import com.matedroid.data.repository.TeslamateRepository
 import io.mockk.coEvery
 import io.mockk.coVerify
@@ -29,6 +32,7 @@ class DashboardViewModelTest {
 
     private val testDispatcher = StandardTestDispatcher()
     private lateinit var repository: TeslamateRepository
+    private lateinit var geocodingRepository: GeocodingRepository
     private lateinit var viewModel: DashboardViewModel
 
     private val testCar = CarData(
@@ -50,10 +54,16 @@ class DashboardViewModelTest {
         carStatus = CarStatusDetails(locked = true)
     )
 
+    private val testStatusWithUnits = CarStatusWithUnits(
+        status = testStatus,
+        units = Units()
+    )
+
     @Before
     fun setup() {
         Dispatchers.setMain(testDispatcher)
         repository = mockk()
+        geocodingRepository = mockk()
     }
 
     @After
@@ -62,13 +72,15 @@ class DashboardViewModelTest {
     }
 
     private fun createViewModel(): DashboardViewModel {
-        return DashboardViewModel(repository)
+        return DashboardViewModel(repository, geocodingRepository)
     }
 
     @Test
     fun `loadCars fetches cars and selects first one`() = runTest {
         coEvery { repository.getCars() } returns ApiResult.Success(listOf(testCar))
-        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(testStatus)
+        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(testStatusWithUnits)
+        coEvery { repository.getCharges(1, null, null) } returns ApiResult.Success(emptyList())
+        coEvery { repository.getDrives(1, null, null) } returns ApiResult.Success(emptyList())
 
         viewModel = createViewModel()
         testDispatcher.scheduler.advanceUntilIdle()
@@ -108,10 +120,13 @@ class DashboardViewModelTest {
         val car1 = CarData(carId = 1, name = "Car 1")
         val car2 = CarData(carId = 2, name = "Car 2")
         val status2 = testStatus.copy(displayName = "Car 2")
+        val status2WithUnits = CarStatusWithUnits(status = status2, units = Units())
 
         coEvery { repository.getCars() } returns ApiResult.Success(listOf(car1, car2))
-        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(testStatus)
-        coEvery { repository.getCarStatus(2) } returns ApiResult.Success(status2)
+        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(testStatusWithUnits)
+        coEvery { repository.getCarStatus(2) } returns ApiResult.Success(status2WithUnits)
+        coEvery { repository.getCharges(any(), null, null) } returns ApiResult.Success(emptyList())
+        coEvery { repository.getDrives(any(), null, null) } returns ApiResult.Success(emptyList())
 
         viewModel = createViewModel()
         testDispatcher.scheduler.advanceUntilIdle()
@@ -128,7 +143,9 @@ class DashboardViewModelTest {
     @Test
     fun `refresh reloads car status`() = runTest {
         coEvery { repository.getCars() } returns ApiResult.Success(listOf(testCar))
-        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(testStatus)
+        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(testStatusWithUnits)
+        coEvery { repository.getCharges(1, null, null) } returns ApiResult.Success(emptyList())
+        coEvery { repository.getDrives(1, null, null) } returns ApiResult.Success(emptyList())
 
         viewModel = createViewModel()
         testDispatcher.scheduler.advanceUntilIdle()
@@ -136,7 +153,8 @@ class DashboardViewModelTest {
         val updatedStatus = testStatus.copy(
             batteryDetails = BatteryDetails(batteryLevel = 80, ratedBatteryRange = 300.0)
         )
-        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(updatedStatus)
+        val updatedStatusWithUnits = CarStatusWithUnits(status = updatedStatus, units = Units())
+        coEvery { repository.getCarStatus(1) } returns ApiResult.Success(updatedStatusWithUnits)
 
         viewModel.refresh()
         testDispatcher.scheduler.advanceUntilIdle()
@@ -178,6 +196,8 @@ class DashboardViewModelTest {
     fun `status error is shown when status fetch fails`() = runTest {
         coEvery { repository.getCars() } returns ApiResult.Success(listOf(testCar))
         coEvery { repository.getCarStatus(1) } returns ApiResult.Error("Status error")
+        coEvery { repository.getCharges(1, null, null) } returns ApiResult.Success(emptyList())
+        coEvery { repository.getDrives(1, null, null) } returns ApiResult.Success(emptyList())
 
         viewModel = createViewModel()
         testDispatcher.scheduler.advanceUntilIdle()