feat: add persistent interface settings

android/app/src/androidTest/kotlin/com/flagship/abox/manager/ui/preferences/SettingsScreenTest.kt

@@ -0,0 +1,90 @@
+package com.flagship.abox.manager.ui.preferences
+
+import androidx.activity.ComponentActivity
+import androidx.compose.foundation.layout.Column
+import androidx.compose.material3.Text
+import androidx.compose.ui.unit.dp
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.test.assertIsSelected
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.assertWidthIsAtLeast
+import androidx.compose.ui.test.assertHeightIsAtLeast
+import androidx.compose.ui.test.junit4.createAndroidComposeRule
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.test.performClick
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.flagship.abox.manager.designsystem.ABoxTheme
+import com.flagship.abox.manager.preferences.DesignRenderer
+import com.flagship.abox.manager.preferences.UiPreferences
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class SettingsScreenTest {
+    @get:Rule
+    val composeRule = createAndroidComposeRule<ComponentActivity>()
+
+    @Test
+    fun settingsUsesChineseLabelsSelectedStateAndAccessibleControlBounds() {
+        composeRule.setContent {
+            ABoxTheme {
+                SettingsScreen(
+                    state = SettingsUiState(
+                        preferences = UiPreferences(renderer = DesignRenderer.MATERIAL3),
+                        loaded = true,
+                    ),
+                    onAction = {},
+                )
+            }
+        }
+
+        composeRule.onNodeWithText("界面设置").assertIsDisplayed()
+        composeRule.onNodeWithText("渲染器").assertIsDisplayed()
+        composeRule.onNodeWithText("Material 3").assertIsSelected()
+        composeRule.onNodeWithText("跟随系统").assertIsSelected()
+        composeRule.onNodeWithText("动态取色").assertIsDisplayed()
+        composeRule.onNodeWithText("系统辅助功能").assertIsDisplayed()
+        composeRule.onNodeWithTag("settings-dynamic-color")
+            .assertWidthIsAtLeast(48.dp)
+            .assertHeightIsAtLeast(48.dp)
+        composeRule.onNodeWithTag("settings-blur")
+            .assertWidthIsAtLeast(48.dp)
+            .assertHeightIsAtLeast(48.dp)
+        composeRule.onNodeWithTag("settings-haptics")
+            .assertWidthIsAtLeast(48.dp)
+            .assertHeightIsAtLeast(48.dp)
+    }
+
+    @Test
+    fun switchingRendererKeepsCurrentlyRenderedTestScreenPresent() {
+        var preferences by mutableStateOf(UiPreferences(renderer = DesignRenderer.MATERIAL3))
+        composeRule.setContent {
+            ABoxTheme(preferences = preferences) {
+                Column {
+                    Text("当前测试内容")
+                    SettingsScreen(
+                        state = SettingsUiState(preferences = preferences, loaded = true),
+                        onAction = { action ->
+                            if (action is SettingsUiAction.SetRenderer) {
+                                preferences = preferences.copy(renderer = action.value)
+                            }
+                        },
+                        modifier = Modifier.weight(1f),
+                    )
+                }
+            }
+        }
+
+        composeRule.onNodeWithText("Miuix").performClick()
+        composeRule.waitForIdle()
+
+        composeRule.onNodeWithText("当前测试内容").assertIsDisplayed()
+        composeRule.onNodeWithText("Miuix").assertIsSelected()
+    }
+}

android/app/src/main/kotlin/com/flagship/abox/manager/di/UiPreferencesModule.kt

@@ -0,0 +1,21 @@
+package com.flagship.abox.manager.di
+
+import android.content.Context
+import com.flagship.abox.manager.preferences.DataStoreUiPreferencesRepository
+import com.flagship.abox.manager.preferences.UiPreferencesRepository
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+object UiPreferencesModule {
+    @Provides
+    @Singleton
+    fun provideUiPreferencesRepository(
+        @ApplicationContext context: Context,
+    ): UiPreferencesRepository = DataStoreUiPreferencesRepository(context)
+}

android/app/src/main/kotlin/com/flagship/abox/manager/ui/ABoxManagerApp.kt

@@ -32,6 +32,7 @@ import com.flagship.abox.manager.ui.navigation.deviceDetailGraph
 import com.flagship.abox.manager.ui.navigation.navigateToSocket
 import com.flagship.abox.manager.ui.navigation.navigateToTemperatureHumidity
 import com.flagship.abox.manager.ui.provider.ProviderSelectionRoute
+import com.flagship.abox.manager.ui.preferences.SettingsViewModel
 import com.flagship.abox.manager.ui.scene.SceneListScreen
 import com.flagship.abox.manager.ui.scene.SceneRoutes
 import com.flagship.abox.manager.ui.scene.sceneEditorDestination
@@ -46,9 +47,11 @@ fun ABoxManagerApp(
     appSessionViewModel: AppSessionViewModel = hiltViewModel(),
     sessionActionsViewModel: SessionActionsViewModel = hiltViewModel(),
     loginViewModel: LoginViewModel = hiltViewModel(),
+    settingsViewModel: SettingsViewModel = hiltViewModel(),
 ) {
     val actionState = sessionActionsViewModel.uiState.collectAsStateWithLifecycle().value
     val sessionState = appSessionViewModel.uiState.collectAsStateWithLifecycle().value
+    val settingsState = settingsViewModel.uiState.collectAsStateWithLifecycle().value
     val screenKey = sessionState.screenKey()
     LaunchedEffect(screenKey) {
         sessionActionsViewModel.dismissError()
@@ -56,7 +59,7 @@ fun ABoxManagerApp(
             loginViewModel.clearSensitiveState()
         }
     }
-    ABoxTheme {
+    ABoxTheme(preferences = settingsState.preferences) {
         ABoxSurface(modifier = Modifier.fillMaxSize()) {
             when (val state = sessionState) {
                 AppSessionUiState.Loading -> Box(

android/app/src/main/kotlin/com/flagship/abox/manager/ui/preferences/SettingsScreen.kt

@@ -0,0 +1,227 @@
+package com.flagship.abox.manager.ui.preferences
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import com.flagship.abox.manager.R
+import com.flagship.abox.manager.designsystem.ABoxCard
+import com.flagship.abox.manager.designsystem.ABoxErrorState
+import com.flagship.abox.manager.designsystem.ABoxFilterChip
+import com.flagship.abox.manager.designsystem.ABoxPreferenceGroup
+import com.flagship.abox.manager.designsystem.ABoxSwitch
+import com.flagship.abox.manager.preferences.AppThemeMode
+import com.flagship.abox.manager.preferences.DesignRenderer
+import com.flagship.abox.manager.preferences.NavigationPresentation
+
+@Composable
+fun SettingsRoute(
+    viewModel: SettingsViewModel = hiltViewModel(),
+) {
+    val state = viewModel.uiState.collectAsStateWithLifecycle().value
+    SettingsScreen(state = state, onAction = viewModel::onAction)
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun SettingsScreen(
+    state: SettingsUiState,
+    onAction: (SettingsUiAction) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Scaffold(
+        modifier = modifier.fillMaxSize(),
+        topBar = { TopAppBar(title = { Text(stringResource(R.string.settings_title)) }) },
+    ) { contentPadding ->
+        Column(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(contentPadding)
+                .verticalScroll(rememberScrollState())
+                .padding(horizontal = 16.dp, vertical = 12.dp),
+            verticalArrangement = Arrangement.spacedBy(16.dp),
+        ) {
+            ABoxPreferenceGroup(title = stringResource(R.string.settings_style_section)) {
+                PreferenceRow(
+                    title = stringResource(R.string.settings_renderer_label),
+                    description = stringResource(R.string.settings_renderer_description),
+                ) {
+                    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                        ABoxFilterChip(
+                            selected = state.preferences.renderer == DesignRenderer.MATERIAL3,
+                            label = stringResource(R.string.settings_renderer_material3),
+                            onClick = { onAction(SettingsUiAction.SetRenderer(DesignRenderer.MATERIAL3)) },
+                        )
+                        ABoxFilterChip(
+                            selected = state.preferences.renderer == DesignRenderer.MIUIX,
+                            label = stringResource(R.string.settings_renderer_miuix),
+                            onClick = { onAction(SettingsUiAction.SetRenderer(DesignRenderer.MIUIX)) },
+                        )
+                    }
+                }
+            }
+
+            ABoxPreferenceGroup(title = stringResource(R.string.settings_theme_section)) {
+                PreferenceRow(
+                    title = stringResource(R.string.settings_theme_label),
+                    description = null,
+                ) {
+                    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                        ThemeChip(AppThemeMode.SYSTEM, state, onAction, R.string.settings_theme_system)
+                        ThemeChip(AppThemeMode.LIGHT, state, onAction, R.string.settings_theme_light)
+                        ThemeChip(AppThemeMode.DARK, state, onAction, R.string.settings_theme_dark)
+                    }
+                }
+                SwitchPreference(
+                    title = stringResource(R.string.settings_dynamic_color),
+                    description = stringResource(R.string.settings_dynamic_color_description),
+                    checked = state.preferences.dynamicColorEnabled,
+                    modifier = Modifier.testTag("settings-dynamic-color"),
+                    onCheckedChange = { onAction(SettingsUiAction.SetDynamicColor(it)) },
+                )
+            }
+
+            ABoxPreferenceGroup(title = stringResource(R.string.settings_surface_section)) {
+                SwitchPreference(
+                    title = stringResource(R.string.settings_blur),
+                    description = stringResource(R.string.settings_blur_description),
+                    checked = state.preferences.blurEnabled,
+                    modifier = Modifier.testTag("settings-blur"),
+                    onCheckedChange = { onAction(SettingsUiAction.SetBlur(it)) },
+                )
+                PreferenceRow(
+                    title = stringResource(R.string.settings_navigation),
+                    description = null,
+                ) {
+                    Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                        NavigationChip(
+                            presentation = NavigationPresentation.STANDARD,
+                            selected = state.preferences.navigationPresentation == NavigationPresentation.STANDARD,
+                            label = stringResource(R.string.settings_navigation_standard),
+                            onAction = onAction,
+                        )
+                        NavigationChip(
+                            presentation = NavigationPresentation.FLOATING,
+                            selected = state.preferences.navigationPresentation == NavigationPresentation.FLOATING,
+                            label = stringResource(R.string.settings_navigation_floating),
+                            onAction = onAction,
+                        )
+                    }
+                }
+            }
+
+            ABoxPreferenceGroup(title = stringResource(R.string.settings_feedback_section)) {
+                SwitchPreference(
+                    title = stringResource(R.string.settings_haptics),
+                    description = stringResource(R.string.settings_haptics_description),
+                    checked = state.preferences.hapticsEnabled,
+                    modifier = Modifier.testTag("settings-haptics"),
+                    onCheckedChange = { onAction(SettingsUiAction.SetHaptics(it)) },
+                )
+            }
+
+            ABoxPreferenceGroup(title = stringResource(R.string.settings_accessibility_section)) {
+                ABoxCard(
+                    title = stringResource(R.string.settings_accessibility_card_title),
+                    subtitle = stringResource(R.string.settings_accessibility_description),
+                )
+            }
+
+            state.error?.let { error ->
+                ABoxErrorState(
+                    title = stringResource(R.string.settings_error_save),
+                    description = error.asString(),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun ThemeChip(
+    mode: AppThemeMode,
+    state: SettingsUiState,
+    onAction: (SettingsUiAction) -> Unit,
+    labelRes: Int,
+) {
+    ABoxFilterChip(
+        selected = state.preferences.themeMode == mode,
+        label = stringResource(labelRes),
+        onClick = { onAction(SettingsUiAction.SetThemeMode(mode)) },
+    )
+}
+
+@Composable
+private fun NavigationChip(
+    presentation: NavigationPresentation,
+    selected: Boolean,
+    label: String,
+    onAction: (SettingsUiAction) -> Unit,
+) {
+    ABoxFilterChip(
+        selected = selected,
+        label = label,
+        onClick = { onAction(SettingsUiAction.SetNavigation(presentation)) },
+    )
+}
+
+@Composable
+private fun PreferenceRow(
+    title: String,
+    description: String?,
+    content: @Composable () -> Unit,
+) {
+    Column(
+        modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp),
+        verticalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        Text(text = title, style = MaterialTheme.typography.titleMedium)
+        description?.let {
+            Text(text = it, style = MaterialTheme.typography.bodyMedium, color = MaterialTheme.colorScheme.onSurfaceVariant)
+        }
+        content()
+    }
+}
+
+@Composable
+private fun SwitchPreference(
+    title: String,
+    description: String,
+    checked: Boolean,
+    modifier: Modifier,
+    onCheckedChange: (Boolean) -> Unit,
+) {
+    Row(
+        modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(12.dp),
+    ) {
+        Column(modifier = Modifier.weight(1f)) {
+            Text(text = title, style = MaterialTheme.typography.titleMedium)
+            Text(text = description, style = MaterialTheme.typography.bodyMedium, color = MaterialTheme.colorScheme.onSurfaceVariant)
+        }
+        ABoxSwitch(
+            checked = checked,
+            onCheckedChange = onCheckedChange,
+            contentDescription = title,
+            modifier = modifier,
+        )
+    }
+}

android/app/src/main/kotlin/com/flagship/abox/manager/ui/preferences/SettingsViewModel.kt

@@ -0,0 +1,122 @@
+package com.flagship.abox.manager.ui.preferences
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.flagship.abox.manager.R
+import com.flagship.abox.manager.preferences.AppThemeMode
+import com.flagship.abox.manager.preferences.DesignRenderer
+import com.flagship.abox.manager.preferences.NavigationPresentation
+import com.flagship.abox.manager.preferences.PreferenceField
+import com.flagship.abox.manager.preferences.UiPreferences
+import com.flagship.abox.manager.preferences.UiPreferencesRepository
+import com.flagship.abox.manager.preferences.UiPreferencesWriteResult
+import com.flagship.abox.manager.ui.common.UiText
+import dagger.hilt.android.lifecycle.HiltViewModel
+import javax.inject.Inject
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.launch
+
+@HiltViewModel
+class SettingsViewModel @Inject constructor(
+    private val repository: UiPreferencesRepository,
+) : ViewModel() {
+    private val _uiState = MutableStateFlow(SettingsUiState())
+    val uiState: StateFlow<SettingsUiState> = _uiState.asStateFlow()
+
+    private val observeJob: Job = viewModelScope.launch {
+        repository.observe().collect { preferences ->
+            _uiState.value = _uiState.value.copy(
+                preferences = preferences,
+                loaded = true,
+            )
+        }
+    }
+
+    fun onAction(action: SettingsUiAction) {
+        when (action) {
+            is SettingsUiAction.SetRenderer -> update(
+                field = PreferenceField.RENDERER,
+                transform = { it.copy(renderer = action.value) },
+            )
+            is SettingsUiAction.SetThemeMode -> update(
+                field = PreferenceField.THEME_MODE,
+                transform = { it.copy(themeMode = action.value) },
+            )
+            is SettingsUiAction.SetDynamicColor -> update(
+                field = PreferenceField.DYNAMIC_COLOR,
+                transform = { it.copy(dynamicColorEnabled = action.value) },
+            )
+            is SettingsUiAction.SetBlur -> update(
+                field = PreferenceField.BLUR,
+                transform = { it.copy(blurEnabled = action.value) },
+            )
+            is SettingsUiAction.SetNavigation -> update(
+                field = PreferenceField.NAVIGATION,
+                transform = { it.copy(navigationPresentation = action.value) },
+            )
+            is SettingsUiAction.SetHaptics -> update(
+                field = PreferenceField.HAPTICS,
+                transform = { it.copy(hapticsEnabled = action.value) },
+            )
+            SettingsUiAction.DismissError -> _uiState.value = _uiState.value.copy(error = null)
+        }
+    }
+
+    private fun update(
+        field: PreferenceField,
+        transform: (UiPreferences) -> UiPreferences,
+    ) {
+        if (field in _uiState.value.saving) return
+        _uiState.value = _uiState.value.copy(
+            saving = _uiState.value.saving + field,
+            error = null,
+        )
+        viewModelScope.launch {
+            try {
+                when (repository.update(transform)) {
+                    UiPreferencesWriteResult.Success -> Unit
+                    UiPreferencesWriteResult.Failure -> showWriteFailure(field)
+                }
+            } catch (cause: CancellationException) {
+                throw cause
+            } catch (_: Throwable) {
+                showWriteFailure(field)
+            } finally {
+                _uiState.value = _uiState.value.copy(saving = _uiState.value.saving - field)
+            }
+        }
+    }
+
+    private fun showWriteFailure(field: PreferenceField) {
+        _uiState.value = _uiState.value.copy(
+            error = UiText.StringResource(R.string.settings_error_save),
+            saving = _uiState.value.saving - field,
+        )
+    }
+
+    override fun onCleared() {
+        observeJob.cancel()
+        super.onCleared()
+    }
+}
+
+data class SettingsUiState(
+    val preferences: UiPreferences = UiPreferences(),
+    val loaded: Boolean = false,
+    val saving: Set<PreferenceField> = emptySet(),
+    val error: UiText? = null,
+)
+
+sealed interface SettingsUiAction {
+    data class SetRenderer(val value: DesignRenderer) : SettingsUiAction
+    data class SetThemeMode(val value: AppThemeMode) : SettingsUiAction
+    data class SetDynamicColor(val value: Boolean) : SettingsUiAction
+    data class SetBlur(val value: Boolean) : SettingsUiAction
+    data class SetNavigation(val value: NavigationPresentation) : SettingsUiAction
+    data class SetHaptics(val value: Boolean) : SettingsUiAction
+    data object DismissError : SettingsUiAction
+}

android/app/src/main/res/values/strings.xml

@@ -259,4 +259,32 @@
     <string name="error_operation_failed">Operation failed. Please try again.</string>
     <string name="error_no_data">No sensor data available.</string>
     <string name="error_unknown">An unexpected error occurred.</string>
+
+    <!-- Interface settings -->
+    <string name="settings_title">界面设置</string>
+    <string name="settings_style_section">样式</string>
+    <string name="settings_renderer_label">渲染器</string>
+    <string name="settings_renderer_description">选择应用使用的界面渲染方式</string>
+    <string name="settings_renderer_material3">Material 3</string>
+    <string name="settings_renderer_miuix">Miuix</string>
+    <string name="settings_theme_section">主题</string>
+    <string name="settings_theme_label">主题模式</string>
+    <string name="settings_theme_system">跟随系统</string>
+    <string name="settings_theme_light">浅色</string>
+    <string name="settings_theme_dark">深色</string>
+    <string name="settings_dynamic_color">动态取色</string>
+    <string name="settings_dynamic_color_description">使用系统壁纸颜色生成界面配色</string>
+    <string name="settings_surface_section">界面效果</string>
+    <string name="settings_blur">模糊效果</string>
+    <string name="settings_blur_description">在支持的界面中启用背景模糊</string>
+    <string name="settings_navigation">导航样式</string>
+    <string name="settings_navigation_standard">标准导航栏</string>
+    <string name="settings_navigation_floating">悬浮导航栏</string>
+    <string name="settings_feedback_section">交互反馈</string>
+    <string name="settings_haptics">触觉反馈</string>
+    <string name="settings_haptics_description">操作时提供轻微震动反馈</string>
+    <string name="settings_accessibility_section">系统辅助功能</string>
+    <string name="settings_accessibility_card_title">遵循系统辅助功能设置</string>
+    <string name="settings_accessibility_description">动画、字体大小和对比度等辅助功能由系统设置控制，应用会遵循系统偏好。</string>
+    <string name="settings_error_save">无法保存界面设置，请重试</string>
 </resources>

android/app/src/test/kotlin/com/flagship/abox/manager/ui/preferences/SettingsViewModelTest.kt

@@ -0,0 +1,111 @@
+package com.flagship.abox.manager.ui.preferences
+
+import com.flagship.abox.manager.R
+import com.flagship.abox.manager.preferences.AppThemeMode
+import com.flagship.abox.manager.preferences.DesignRenderer
+import com.flagship.abox.manager.ui.common.UiText.StringResource
+import com.flagship.abox.manager.preferences.NavigationPresentation
+import com.flagship.abox.manager.preferences.UiPreferences
+import com.flagship.abox.manager.preferences.UiPreferencesRepository
+import com.flagship.abox.manager.preferences.UiPreferencesWriteResult
+import com.flagship.abox.manager.testing.MainDispatcherRule
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class SettingsViewModelTest {
+    @get:Rule
+    val mainDispatcherRule = MainDispatcherRule()
+
+    @Test
+    fun rendererUpdatePersistsWithoutCallingSessionCoordinator() = runTest {
+        val repository = RecordingUiPreferencesRepository()
+        val viewModel = SettingsViewModel(repository)
+        advanceUntilIdle()
+
+        viewModel.onAction(SettingsUiAction.SetRenderer(DesignRenderer.MIUIX))
+        advanceUntilIdle()
+
+        assertEquals(1, repository.updateCalls.size)
+        assertEquals(DesignRenderer.MIUIX, repository.value.renderer)
+        assertEquals(DesignRenderer.MIUIX, viewModel.uiState.value.preferences.renderer)
+    }
+
+    @Test
+    fun writeFailureLeavesLastValueAndShowsLocalizedError() = runTest {
+        val repository = RecordingUiPreferencesRepository(
+            initial = UiPreferences(renderer = DesignRenderer.MATERIAL3),
+            writeResult = UiPreferencesWriteResult.Failure,
+        )
+        val viewModel = SettingsViewModel(repository)
+        advanceUntilIdle()
+
+        viewModel.onAction(SettingsUiAction.SetRenderer(DesignRenderer.MIUIX))
+        advanceUntilIdle()
+
+        assertEquals(1, repository.updateCalls.size)
+        assertEquals(DesignRenderer.MATERIAL3, viewModel.uiState.value.preferences.renderer)
+        assertTrue(viewModel.uiState.value.error is StringResource)
+        assertEquals(
+            R.string.settings_error_save,
+            (viewModel.uiState.value.error as StringResource).resId,
+        )
+        assertTrue(viewModel.uiState.value.saving.isEmpty())
+    }
+
+    @Test
+    fun collectsRepositoryChanges() = runTest {
+        val repository = RecordingUiPreferencesRepository()
+        val viewModel = SettingsViewModel(repository)
+        advanceUntilIdle()
+
+        repository.emit(
+            UiPreferences(
+                renderer = DesignRenderer.MIUIX,
+                themeMode = AppThemeMode.DARK,
+                dynamicColorEnabled = false,
+                blurEnabled = true,
+                navigationPresentation = NavigationPresentation.FLOATING,
+                hapticsEnabled = false,
+            ),
+        )
+        advanceUntilIdle()
+
+        assertTrue(viewModel.uiState.value.loaded)
+        assertEquals(repository.value, viewModel.uiState.value.preferences)
+    }
+
+
+    private class RecordingUiPreferencesRepository(
+        initial: UiPreferences = UiPreferences(),
+        private val writeResult: UiPreferencesWriteResult = UiPreferencesWriteResult.Success,
+    ) : UiPreferencesRepository {
+        private val state = MutableStateFlow(initial)
+        val updateCalls = mutableListOf<(UiPreferences) -> UiPreferences>()
+        val value: UiPreferences get() = state.value
+
+        override fun observe(): Flow<UiPreferences> = state.asStateFlow()
+
+        override suspend fun update(
+            transform: (UiPreferences) -> UiPreferences,
+        ): UiPreferencesWriteResult {
+            updateCalls += transform
+            if (writeResult is UiPreferencesWriteResult.Success) {
+                state.value = transform(state.value)
+            }
+            return writeResult
+        }
+
+        fun emit(value: UiPreferences) {
+            state.value = value
+        }
+    }
+}