feat(settings): add sync UI with server configuration and push/pull actions

Closes #45

SettingsScreen:
- Server-URL and API-Key input fields (API-Key masked as password)
- Push (upload) and Pull (download) sync buttons
- Sync status indicator (running/success/error)
- Last sync timestamp display (persisted via Room settings)

SettingsViewModel:
- Inject SyncService for server communication
- pushSync(): exports local inventory to InventoryDto, uploads via SyncService
- pullSync(): downloads InventoryDto from server, imports into local DB
- Persists server_url, api_key, sync_last_timestamp in Room settings table

ImportExportRepository:
- New methods exportToInventoryDto() and importFromInventoryDto()
- Refactored to eliminate code duplication via buildInventoryDto() and
  applyInventoryDto() helper methods

Tests:
- 8 new ViewModel tests covering sync settings loading, push/pull success,
  push/pull error scenarios, and sync status dismissal
- FakeSyncService and extended FakeImportExportRepository for testing

app/src/main/java/de/krisenvorrat/app/data/export/ImportExportRepositoryImpl.kt

@@ -37,12 +37,21 @@ internal class ImportExportRepositoryImpl @Inject constructor(
     }
 
     override suspend fun exportToJson(): String = withContext(Dispatchers.IO) {
+        val exportData = buildInventoryDto()
+        jsonSerializer.encodeToString(InventoryDto.serializer(), exportData)
+    }
+
+    override suspend fun exportToInventoryDto(): InventoryDto = withContext(Dispatchers.IO) {
+        buildInventoryDto()
+    }
+
+    private suspend fun buildInventoryDto(): InventoryDto {
         val categories = categoryDao.getAll().first()
         val locations = locationDao.getAll().first()
         val items = itemDao.getAll().first()
         val settings = settingsDao.getAll().first()
 
-        val exportData = InventoryDto(
+        return InventoryDto(
             categories = categories.map { CategoryDto(id = it.id, name = it.name) },
             locations = locations.map { LocationDto(id = it.id, name = it.name) },
             items = items.map { item ->
@@ -63,34 +72,43 @@ internal class ImportExportRepositoryImpl @Inject constructor(
             },
             settings = settings.map { SettingDto(key = it.key, value = it.value) }
         )
-        jsonSerializer.encodeToString(InventoryDto.serializer(), exportData)
     }
 
     override suspend fun importFromJson(json: String): Result<Unit> = withContext(Dispatchers.IO) {
         runCatching {
             val exportData = jsonSerializer.decodeFromString<InventoryDto>(json)
             check(exportData.version == 1) { "Unsupported export format version: ${exportData.version}" }
-            transaction.execute {
-                categoryDao.upsertAll(exportData.categories.map { CategoryEntity(id = it.id, name = it.name) })
-                locationDao.upsertAll(exportData.locations.map { LocationEntity(id = it.id, name = it.name) })
-                itemDao.upsertAll(exportData.items.map { item ->
-                    ItemEntity(
-                        id = item.id,
-                        name = item.name,
-                        categoryId = item.categoryId,
-                        quantity = item.quantity,
-                        unit = item.unit,
-                        unitPrice = item.unitPrice,
-                        kcalPer100g = item.kcalPer100g,
-                        expiryDate = item.expiryDate?.let { LocalDate.parse(it) },
-                        locationId = item.locationId,
-                        minStock = item.minStock,
-                        notes = item.notes,
-                        lastUpdated = item.lastUpdated
-                    )
-                })
-                settingsDao.upsertAll(exportData.settings.map { SettingsEntity(key = it.key, value = it.value) })
-            }
+            applyInventoryDto(exportData)
+        }
+    }
+
+    override suspend fun importFromInventoryDto(dto: InventoryDto): Result<Unit> = withContext(Dispatchers.IO) {
+        runCatching {
+            applyInventoryDto(dto)
+        }
+    }
+
+    private suspend fun applyInventoryDto(dto: InventoryDto) {
+        transaction.execute {
+            categoryDao.upsertAll(dto.categories.map { CategoryEntity(id = it.id, name = it.name) })
+            locationDao.upsertAll(dto.locations.map { LocationEntity(id = it.id, name = it.name) })
+            itemDao.upsertAll(dto.items.map { item ->
+                ItemEntity(
+                    id = item.id,
+                    name = item.name,
+                    categoryId = item.categoryId,
+                    quantity = item.quantity,
+                    unit = item.unit,
+                    unitPrice = item.unitPrice,
+                    kcalPer100g = item.kcalPer100g,
+                    expiryDate = item.expiryDate?.let { LocalDate.parse(it) },
+                    locationId = item.locationId,
+                    minStock = item.minStock,
+                    notes = item.notes,
+                    lastUpdated = item.lastUpdated
+                )
+            })
+            settingsDao.upsertAll(dto.settings.map { SettingsEntity(key = it.key, value = it.value) })
         }
     }
 

app/src/main/java/de/krisenvorrat/app/domain/repository/ImportExportRepository.kt

@@ -1,7 +1,11 @@
 package de.krisenvorrat.app.domain.repository
 
+import de.krisenvorrat.shared.model.InventoryDto
+
 internal interface ImportExportRepository {
     suspend fun exportToJson(): String
     suspend fun importFromJson(json: String): Result<Unit>
     suspend fun exportToMarkdown(): String
+    suspend fun exportToInventoryDto(): InventoryDto
+    suspend fun importFromInventoryDto(dto: InventoryDto): Result<Unit>
 }

app/src/main/java/de/krisenvorrat/app/ui/settings/SettingsScreen.kt

@@ -4,12 +4,16 @@ import android.content.Intent
 import android.widget.Toast
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.foundation.verticalScroll
@@ -27,9 +31,11 @@ import androidx.compose.material3.TopAppBar
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.text.input.PasswordVisualTransformation
 import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
@@ -184,6 +190,109 @@ internal fun SettingsScreen(
                         modifier = Modifier.padding(8.dp)
                     )
                 }
+
+                Spacer(modifier = Modifier.height(32.dp))
+
+                HorizontalDivider()
+
+                Spacer(modifier = Modifier.height(16.dp))
+
+                Text(
+                    text = "Server-Synchronisierung",
+                    style = MaterialTheme.typography.titleMedium
+                )
+
+                Spacer(modifier = Modifier.height(12.dp))
+
+                OutlinedTextField(
+                    value = uiState.serverUrl,
+                    onValueChange = viewModel::onServerUrlChanged,
+                    label = { Text("Server-URL") },
+                    placeholder = { Text("https://example.com") },
+                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Uri),
+                    singleLine = true,
+                    modifier = Modifier.fillMaxWidth()
+                )
+
+                Spacer(modifier = Modifier.height(12.dp))
+
+                OutlinedTextField(
+                    value = uiState.apiKey,
+                    onValueChange = viewModel::onApiKeyChanged,
+                    label = { Text("API-Key") },
+                    visualTransformation = PasswordVisualTransformation(),
+                    singleLine = true,
+                    modifier = Modifier.fillMaxWidth()
+                )
+
+                Spacer(modifier = Modifier.height(16.dp))
+
+                val isSyncEnabled = uiState.serverUrl.isNotBlank() &&
+                    uiState.apiKey.isNotBlank() &&
+                    uiState.syncStatus !is SyncStatus.Running
+
+                Row(
+                    modifier = Modifier.fillMaxWidth(),
+                    horizontalArrangement = Arrangement.spacedBy(8.dp)
+                ) {
+                    OutlinedButton(
+                        onClick = viewModel::pushSync,
+                        enabled = isSyncEnabled,
+                        modifier = Modifier.weight(1f)
+                    ) {
+                        Text("Push (Hochladen)")
+                    }
+
+                    OutlinedButton(
+                        onClick = viewModel::pullSync,
+                        enabled = isSyncEnabled,
+                        modifier = Modifier.weight(1f)
+                    ) {
+                        Text("Pull (Herunterladen)")
+                    }
+                }
+
+                when (val syncStatus = uiState.syncStatus) {
+                    is SyncStatus.Running -> {
+                        Spacer(modifier = Modifier.height(12.dp))
+                        Row(
+                            verticalAlignment = Alignment.CenterVertically
+                        ) {
+                            CircularProgressIndicator(modifier = Modifier.size(20.dp))
+                            Spacer(modifier = Modifier.width(8.dp))
+                            Text(
+                                text = "Synchronisierung läuft…",
+                                style = MaterialTheme.typography.bodySmall
+                            )
+                        }
+                    }
+                    is SyncStatus.Success -> {
+                        Spacer(modifier = Modifier.height(12.dp))
+                        Text(
+                            text = "Synchronisierung erfolgreich",
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.primary
+                        )
+                    }
+                    is SyncStatus.Error -> {
+                        Spacer(modifier = Modifier.height(12.dp))
+                        Text(
+                            text = syncStatus.message,
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.error
+                        )
+                    }
+                    is SyncStatus.Idle -> { /* no indicator */ }
+                }
+
+                if (uiState.lastSyncTime != null) {
+                    Spacer(modifier = Modifier.height(8.dp))
+                    Text(
+                        text = "Letzte Synchronisierung: ${uiState.lastSyncTime}",
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant
+                    )
+                }
             }
         }
     }

app/src/main/java/de/krisenvorrat/app/ui/settings/SettingsUiState.kt

@@ -12,9 +12,20 @@ internal data class SettingsUiState(
     val exportError: String? = null,
     val isImporting: Boolean = false,
     val importResult: ImportResult? = null,
-    val pendingImportUri: Uri? = null
+    val pendingImportUri: Uri? = null,
+    val serverUrl: String = "",
+    val apiKey: String = "",
+    val syncStatus: SyncStatus = SyncStatus.Idle,
+    val lastSyncTime: String? = null
 )
 
+internal sealed interface SyncStatus {
+    data object Idle : SyncStatus
+    data object Running : SyncStatus
+    data object Success : SyncStatus
+    data class Error(val message: String) : SyncStatus
+}
+
 internal sealed interface ImportResult {
     data object Success : ImportResult
     data class Error(val message: String) : ImportResult

app/src/main/java/de/krisenvorrat/app/ui/settings/SettingsViewModel.kt

@@ -9,6 +9,7 @@ import dagger.hilt.android.lifecycle.HiltViewModel
 import dagger.hilt.android.qualifiers.ApplicationContext
 import de.krisenvorrat.app.domain.repository.ImportExportRepository
 import de.krisenvorrat.app.domain.repository.SettingsRepository
+import de.krisenvorrat.app.domain.repository.SyncService
 import de.krisenvorrat.app.domain.usecase.CalculateSupplyRangeUseCase
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -16,12 +17,17 @@ import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import java.io.File
+import java.time.Instant
+import java.time.ZoneId
+import java.time.format.DateTimeFormatter
+import java.util.Locale
 import javax.inject.Inject
 
 @HiltViewModel
 internal class SettingsViewModel @Inject constructor(
     private val settingsRepository: SettingsRepository,
     private val importExportRepository: ImportExportRepository,
+    private val syncService: SyncService,
     @ApplicationContext private val context: Context
 ) : ViewModel() {
 
@@ -39,11 +45,17 @@ internal class SettingsViewModel @Inject constructor(
                     ?: CalculateSupplyRangeUseCase.DEFAULT_HOUSEHOLD_SIZE.toString()
                 val dailyKcal = settingsRepository.getValue(KEY_DAILY_KCAL_PER_PERSON)
                     ?: CalculateSupplyRangeUseCase.DEFAULT_DAILY_KCAL_PER_PERSON.toString()
+                val serverUrl = settingsRepository.getValue(KEY_SERVER_URL) ?: ""
+                val apiKey = settingsRepository.getValue(KEY_API_KEY) ?: ""
+                val lastSyncTimestamp = settingsRepository.getValue(KEY_SYNC_LAST_TIMESTAMP)
 
                 _uiState.update {
                     it.copy(
                         householdSize = householdSize,
                         dailyKcalPerPerson = dailyKcal,
+                        serverUrl = serverUrl,
+                        apiKey = apiKey,
+                        lastSyncTime = lastSyncTimestamp?.let { ts -> formatTimestamp(ts) },
                         isLoading = false
                     )
                 }
@@ -67,6 +79,14 @@ internal class SettingsViewModel @Inject constructor(
         _uiState.update { it.copy(dailyKcalPerPerson = value, isSaved = false) }
     }
 
+    fun onServerUrlChanged(value: String) {
+        _uiState.update { it.copy(serverUrl = value, isSaved = false) }
+    }
+
+    fun onApiKeyChanged(value: String) {
+        _uiState.update { it.copy(apiKey = value, isSaved = false) }
+    }
+
     fun saveSettings() {
         viewModelScope.launch {
             try {
@@ -80,6 +100,9 @@ internal class SettingsViewModel @Inject constructor(
                     settingsRepository.setValue(KEY_DAILY_KCAL_PER_PERSON, dailyKcal)
                 }
 
+                settingsRepository.setValue(KEY_SERVER_URL, _uiState.value.serverUrl)
+                settingsRepository.setValue(KEY_API_KEY, _uiState.value.apiKey)
+
                 _uiState.update { it.copy(isSaved = true) }
             } catch (e: Exception) {
                 // Fehler beim Speichern – UI zeigt keinen Saved-Status
@@ -166,8 +189,93 @@ internal class SettingsViewModel @Inject constructor(
         _uiState.update { it.copy(importResult = null) }
     }
 
+    fun pushSync() {
+        viewModelScope.launch {
+            _uiState.update { it.copy(syncStatus = SyncStatus.Running) }
+            try {
+                val inventoryDto = importExportRepository.exportToInventoryDto()
+                val result = syncService.uploadInventory(inventoryDto)
+                result.fold(
+                    onSuccess = {
+                        val now = Instant.now().toEpochMilli().toString()
+                        settingsRepository.setValue(KEY_SYNC_LAST_TIMESTAMP, now)
+                        _uiState.update {
+                            it.copy(
+                                syncStatus = SyncStatus.Success,
+                                lastSyncTime = formatTimestamp(now)
+                            )
+                        }
+                    },
+                    onFailure = { e ->
+                        _uiState.update {
+                            it.copy(syncStatus = SyncStatus.Error(e.message ?: "Push fehlgeschlagen"))
+                        }
+                    }
+                )
+            } catch (e: Exception) {
+                _uiState.update {
+                    it.copy(syncStatus = SyncStatus.Error(e.message ?: "Push fehlgeschlagen"))
+                }
+            }
+        }
+    }
+
+    fun pullSync() {
+        viewModelScope.launch {
+            _uiState.update { it.copy(syncStatus = SyncStatus.Running) }
+            try {
+                val result = syncService.downloadInventory()
+                result.fold(
+                    onSuccess = { inventoryDto ->
+                        importExportRepository.importFromInventoryDto(inventoryDto).fold(
+                            onSuccess = {
+                                val now = Instant.now().toEpochMilli().toString()
+                                settingsRepository.setValue(KEY_SYNC_LAST_TIMESTAMP, now)
+                                loadSettings()
+                                _uiState.update {
+                                    it.copy(
+                                        syncStatus = SyncStatus.Success,
+                                        lastSyncTime = formatTimestamp(now)
+                                    )
+                                }
+                            },
+                            onFailure = { e ->
+                                _uiState.update {
+                                    it.copy(syncStatus = SyncStatus.Error(e.message ?: "Import fehlgeschlagen"))
+                                }
+                            }
+                        )
+                    },
+                    onFailure = { e ->
+                        _uiState.update {
+                            it.copy(syncStatus = SyncStatus.Error(e.message ?: "Pull fehlgeschlagen"))
+                        }
+                    }
+                )
+            } catch (e: Exception) {
+                _uiState.update {
+                    it.copy(syncStatus = SyncStatus.Error(e.message ?: "Pull fehlgeschlagen"))
+                }
+            }
+        }
+    }
+
+    fun onSyncStatusDismissed() {
+        _uiState.update { it.copy(syncStatus = SyncStatus.Idle) }
+    }
+
+    private fun formatTimestamp(epochMillisStr: String): String? {
+        val millis = epochMillisStr.toLongOrNull() ?: return null
+        val instant = Instant.ofEpochMilli(millis)
+        val formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm", Locale.GERMAN)
+        return formatter.format(instant.atZone(ZoneId.systemDefault()))
+    }
+
     companion object {
         const val KEY_HOUSEHOLD_SIZE = "household_size"
         const val KEY_DAILY_KCAL_PER_PERSON = "daily_kcal_per_person"
+        const val KEY_SERVER_URL = "server_url"
+        const val KEY_API_KEY = "api_key"
+        const val KEY_SYNC_LAST_TIMESTAMP = "sync_last_timestamp"
     }
 }

app/src/test/java/de/krisenvorrat/app/ui/settings/SettingsViewModelTest.kt

@@ -5,9 +5,12 @@ import androidx.core.content.FileProvider
 import android.content.ContentResolver
 import android.net.Uri
 import de.krisenvorrat.app.data.db.entity.SettingsEntity
+import de.krisenvorrat.app.domain.model.SyncError
 import de.krisenvorrat.app.domain.repository.ImportExportRepository
 import de.krisenvorrat.app.domain.repository.SettingsRepository
+import de.krisenvorrat.app.domain.repository.SyncService
 import de.krisenvorrat.app.domain.usecase.CalculateSupplyRangeUseCase
+import de.krisenvorrat.shared.model.InventoryDto
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
@@ -38,6 +41,7 @@ class SettingsViewModelTest {
     private val testDispatcher = StandardTestDispatcher()
     private lateinit var fakeSettingsRepository: FakeSettingsRepository
     private lateinit var fakeImportExportRepository: FakeImportExportRepository
+    private lateinit var fakeSyncService: FakeSyncService
     private lateinit var mockContext: Context
     private lateinit var tempDir: File
     private lateinit var viewModel: SettingsViewModel
@@ -47,6 +51,7 @@ class SettingsViewModelTest {
         Dispatchers.setMain(testDispatcher)
         fakeSettingsRepository = FakeSettingsRepository()
         fakeImportExportRepository = FakeImportExportRepository()
+        fakeSyncService = FakeSyncService()
         tempDir = File(System.getProperty("java.io.tmpdir"), "test_exports")
         tempDir.mkdirs()
         mockContext = mockk(relaxed = true) {
@@ -64,6 +69,7 @@ class SettingsViewModelTest {
     private fun createViewModel() = SettingsViewModel(
         settingsRepository = fakeSettingsRepository,
         importExportRepository = fakeImportExportRepository,
+        syncService = fakeSyncService,
         context = mockContext
     )
 
@@ -446,6 +452,159 @@ class SettingsViewModelTest {
         // Then
         assertNull(viewModel.uiState.value.importResult)
     }
+
+    // --- Sync Tests ---
+
+    @Test
+    fun test_init_withStoredSyncSettings_loadsSyncFields() = runTest(testDispatcher) {
+        // Given
+        fakeSettingsRepository.store[SettingsViewModel.KEY_SERVER_URL] = "https://example.com"
+        fakeSettingsRepository.store[SettingsViewModel.KEY_API_KEY] = "my-secret-key"
+        fakeSettingsRepository.store[SettingsViewModel.KEY_SYNC_LAST_TIMESTAMP] = "1715700000000"
+
+        viewModel = createViewModel()
+
+        // When
+        advanceUntilIdle()
+
+        // Then
+        val state = viewModel.uiState.value
+        assertEquals("https://example.com", state.serverUrl)
+        assertEquals("my-secret-key", state.apiKey)
+        assertNotNull(state.lastSyncTime)
+    }
+
+    @Test
+    fun test_onServerUrlChanged_updatesState() = runTest(testDispatcher) {
+        // Given
+        viewModel = createViewModel()
+        advanceUntilIdle()
+
+        // When
+        viewModel.onServerUrlChanged("https://new-server.com")
+
+        // Then
+        assertEquals("https://new-server.com", viewModel.uiState.value.serverUrl)
+        assertFalse(viewModel.uiState.value.isSaved)
+    }
+
+    @Test
+    fun test_onApiKeyChanged_updatesState() = runTest(testDispatcher) {
+        // Given
+        viewModel = createViewModel()
+        advanceUntilIdle()
+
+        // When
+        viewModel.onApiKeyChanged("new-api-key")
+
+        // Then
+        assertEquals("new-api-key", viewModel.uiState.value.apiKey)
+        assertFalse(viewModel.uiState.value.isSaved)
+    }
+
+    @Test
+    fun test_saveSettings_persistsServerUrlAndApiKey() = runTest(testDispatcher) {
+        // Given
+        viewModel = createViewModel()
+        advanceUntilIdle()
+        viewModel.onHouseholdSizeChanged("2")
+        viewModel.onServerUrlChanged("https://myserver.com")
+        viewModel.onApiKeyChanged("secret-key-123")
+
+        // When
+        viewModel.saveSettings()
+        advanceUntilIdle()
+
+        // Then
+        assertTrue(viewModel.uiState.value.isSaved)
+        assertEquals("https://myserver.com", fakeSettingsRepository.store[SettingsViewModel.KEY_SERVER_URL])
+        assertEquals("secret-key-123", fakeSettingsRepository.store[SettingsViewModel.KEY_API_KEY])
+    }
+
+    @Test
+    fun test_pushSync_success_updatesSyncStatusAndTimestamp() = runTest(testDispatcher) {
+        // Given
+        viewModel = createViewModel()
+        advanceUntilIdle()
+
+        // When
+        viewModel.pushSync()
+        advanceUntilIdle()
+
+        // Then
+        val state = viewModel.uiState.value
+        assertTrue(state.syncStatus is SyncStatus.Success)
+        assertNotNull(state.lastSyncTime)
+        assertNotNull(fakeSettingsRepository.store[SettingsViewModel.KEY_SYNC_LAST_TIMESTAMP])
+    }
+
+    @Test
+    fun test_pushSync_failure_setsSyncStatusError() = runTest(testDispatcher) {
+        // Given
+        fakeSyncService.uploadShouldFail = true
+        fakeSyncService.uploadError = SyncError.ConnectionError()
+        viewModel = createViewModel()
+        advanceUntilIdle()
+
+        // When
+        viewModel.pushSync()
+        advanceUntilIdle()
+
+        // Then
+        val state = viewModel.uiState.value
+        assertTrue(state.syncStatus is SyncStatus.Error)
+        assertTrue((state.syncStatus as SyncStatus.Error).message.contains("Server nicht erreichbar"))
+    }
+
+    @Test
+    fun test_pullSync_success_updatesSyncStatusAndTimestamp() = runTest(testDispatcher) {
+        // Given
+        viewModel = createViewModel()
+        advanceUntilIdle()
+
+        // When
+        viewModel.pullSync()
+        advanceUntilIdle()
+
+        // Then
+        val state = viewModel.uiState.value
+        assertTrue(state.syncStatus is SyncStatus.Success)
+        assertNotNull(state.lastSyncTime)
+        assertNotNull(fakeSettingsRepository.store[SettingsViewModel.KEY_SYNC_LAST_TIMESTAMP])
+    }
+
+    @Test
+    fun test_pullSync_authError_setsSyncStatusError() = runTest(testDispatcher) {
+        // Given
+        fakeSyncService.downloadShouldFail = true
+        fakeSyncService.downloadError = SyncError.AuthError()
+        viewModel = createViewModel()
+        advanceUntilIdle()
+
+        // When
+        viewModel.pullSync()
+        advanceUntilIdle()
+
+        // Then
+        val state = viewModel.uiState.value
+        assertTrue(state.syncStatus is SyncStatus.Error)
+        assertTrue((state.syncStatus as SyncStatus.Error).message.contains("Authentifizierung"))
+    }
+
+    @Test
+    fun test_onSyncStatusDismissed_resetsSyncStatus() = runTest(testDispatcher) {
+        // Given
+        viewModel = createViewModel()
+        advanceUntilIdle()
+        viewModel.pushSync()
+        advanceUntilIdle()
+
+        // When
+        viewModel.onSyncStatusDismissed()
+
+        // Then
+        assertTrue(viewModel.uiState.value.syncStatus is SyncStatus.Idle)
+    }
 }
 
 // region Test Helpers
@@ -472,6 +631,12 @@ private class FakeImportExportRepository : ImportExportRepository {
     var markdownResult = "# Krisenvorrat Inventar\n"
     var shouldThrow = false
     var importShouldFail = false
+    var inventoryDto = InventoryDto(
+        categories = emptyList(),
+        locations = emptyList(),
+        items = emptyList(),
+        settings = emptyList()
+    )
 
     override suspend fun exportToJson(): String {
         if (shouldThrow) throw RuntimeException("Test error")
@@ -487,6 +652,45 @@ private class FakeImportExportRepository : ImportExportRepository {
         if (shouldThrow) throw RuntimeException("Test error")
         return markdownResult
     }
+
+    override suspend fun exportToInventoryDto(): InventoryDto {
+        if (shouldThrow) throw RuntimeException("Test error")
+        return inventoryDto
+    }
+
+    override suspend fun importFromInventoryDto(dto: InventoryDto): Result<Unit> {
+        if (shouldThrow || importShouldFail) return Result.failure(RuntimeException("Test error"))
+        return Result.success(Unit)
+    }
+}
+
+private class FakeSyncService : SyncService {
+    var uploadShouldFail = false
+    var downloadShouldFail = false
+    var uploadError: Exception = RuntimeException("Upload failed")
+    var downloadError: Exception = RuntimeException("Download failed")
+    var downloadResult = InventoryDto(
+        categories = emptyList(),
+        locations = emptyList(),
+        items = emptyList(),
+        settings = emptyList()
+    )
+    var uploadResult = InventoryDto(
+        categories = emptyList(),
+        locations = emptyList(),
+        items = emptyList(),
+        settings = emptyList()
+    )
+
+    override suspend fun downloadInventory(): Result<InventoryDto> {
+        if (downloadShouldFail) return Result.failure(downloadError)
+        return Result.success(downloadResult)
+    }
+
+    override suspend fun uploadInventory(inventory: InventoryDto): Result<InventoryDto> {
+        if (uploadShouldFail) return Result.failure(uploadError)
+        return Result.success(uploadResult)
+    }
 }
 
 // endregion