feat: add preferences and send empty state

shared/src/commonMain/kotlin/com/vnidrop/app/App.kt

@@ -10,8 +10,13 @@ import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
+import com.vnidrop.app.core.rememberFileSystemService
+import com.vnidrop.app.core.rememberReceiveFolderPicker
 import com.vnidrop.app.core.rememberShareFilePicker
 import com.vnidrop.app.logging.AppLogger
+import com.vnidrop.app.preferences.AppPreferencesDefaults
+import com.vnidrop.app.preferences.AppPreferencesRepository
+import com.vnidrop.app.preferences.createAppPreferencesDataStore
 import com.vnidrop.app.platform.PlatformSystemAppearance
 import com.vnidrop.app.ui.navigation.AppDestination
 import com.vnidrop.app.ui.screens.ReceiveScreen
@@ -19,6 +24,7 @@ import com.vnidrop.app.ui.screens.SendScreen
 import com.vnidrop.app.ui.screens.SettingsScreen
 import com.vnidrop.app.ui.shell.AppShell
 import com.vnidrop.app.ui.state.windowClassFor
+import com.vnidrop.app.ui.theme.ThemeMode
 import com.vnidrop.app.ui.theme.VniDropTheme
 import com.vnidrop.app.ui.theme.rememberResolvedDarkTheme
 
@@ -26,11 +32,23 @@ import com.vnidrop.app.ui.theme.rememberResolvedDarkTheme
 @Preview
 fun App() {
 	val platform = remember { getPlatform() }
+	val fileSystemService = rememberFileSystemService()
+	val preferencesRepository = remember(platform.defaultCoreDataDir) {
+		AppPreferencesRepository(
+			dataStore = createAppPreferencesDataStore(platform.defaultCoreDataDir),
+			defaults = AppPreferencesDefaults(
+				username = platform.deviceInfo.deviceName?.takeIf { it.isNotBlank() } ?: "Receiver",
+				receiveFolder = fileSystemService.defaultReceiveFolder(),
+				themeMode = ThemeMode.System,
+			),
+		)
+	}
 	val viewModel = viewModel {
 		VniDropAppViewModel(
 			appDataDir = platform.defaultCoreDataDir,
-			defaultReceiveDir = platform.defaultReceiveDir,
 			platformName = platform.name,
+			preferencesRepository = preferencesRepository,
+			fileSystemService = fileSystemService,
 		)
 	}
 	val state by viewModel.state.collectAsStateWithLifecycle()
@@ -44,6 +62,14 @@ fun App() {
 			viewModel.onEvent(VniDropAppEvent.ShareFilePickFailed(error))
 		},
 	)
+	val receiveFolderPicker = rememberReceiveFolderPicker(
+		onFolderPicked = { folder ->
+			viewModel.onEvent(VniDropAppEvent.ReceiveFolderPicked(folder))
+		},
+		onError = { error ->
+			viewModel.onEvent(VniDropAppEvent.ReceiveFolderPickFailed(error))
+		},
+	)
 
 	LaunchedEffect(viewModel) {
 		viewModel.effectFlow.collect { effect ->
@@ -52,6 +78,10 @@ fun App() {
 					AppLogger.info("file-picker", "open share file picker")
 					picker.pickFile()
 				}
+				VniDropAppEffect.OpenReceiveFolderPicker -> {
+					AppLogger.info("file-picker", "open receive folder picker")
+					receiveFolderPicker.pickFolder()
+				}
 				is VniDropAppEffect.CopyTicket -> {
 					AppLogger.info("send", "ticket copied")
 					clipboard.setText(AnnotatedString(effect.ticket))
@@ -78,19 +108,22 @@ fun App() {
 					AppDestination.Send -> SendScreen(
 						coreState = coreState,
 						sendState = state.send,
+						windowClass = windowClass,
 						onEvent = viewModel::onEvent,
 					)
 					AppDestination.Receive -> ReceiveScreen(
 						coreState = coreState,
 						receiveState = state.receive,
+						preferencesState = state.preferences,
 						onEvent = viewModel::onEvent,
 					)
 					AppDestination.Settings -> SettingsScreen(
 						deviceInfo = platform.deviceInfo,
 						coreState = coreState,
 						themeMode = state.app.themeMode,
+						preferencesState = state.preferences,
 						windowClass = windowClass,
-						onThemeModeChange = { viewModel.onEvent(VniDropAppEvent.ThemeModeChanged(it)) },
+						onEvent = viewModel::onEvent,
 					)
 				}
 			}

shared/src/commonMain/kotlin/com/vnidrop/app/VniDropAppViewModel.kt

@@ -4,11 +4,18 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.vnidrop.app.core.CoreRepository
 import com.vnidrop.app.core.CoreUiState
+import com.vnidrop.app.core.FileSystemService
+import com.vnidrop.app.core.FolderAccessStatus
 import com.vnidrop.app.core.PickedShareFile
+import com.vnidrop.app.core.ReceiveFolder
+import com.vnidrop.app.core.ReceiveFolderKind
 import com.vnidrop.app.core.sharePickedFile
 import com.vnidrop.app.logging.AppLogger
+import com.vnidrop.app.preferences.AppPreferences
+import com.vnidrop.app.preferences.AppPreferencesRepository
 import com.vnidrop.app.ui.navigation.AppDestination
 import com.vnidrop.app.ui.state.AppUiState
+import com.vnidrop.app.ui.state.PreferencesUiState
 import com.vnidrop.app.ui.state.ReceiveUiState
 import com.vnidrop.app.ui.state.SendUiState
 import com.vnidrop.app.ui.theme.ThemeMode
@@ -21,6 +28,7 @@ import kotlinx.coroutines.launch
 
 data class VniDropAppState(
 	val app: AppUiState = AppUiState(),
+	val preferences: PreferencesUiState = PreferencesUiState(),
 	val send: SendUiState = SendUiState(),
 	val receive: ReceiveUiState = ReceiveUiState(),
 )
@@ -28,6 +36,11 @@ data class VniDropAppState(
 sealed interface VniDropAppEvent {
 	data class DestinationSelected(val destination: AppDestination) : VniDropAppEvent
 	data class ThemeModeChanged(val mode: ThemeMode) : VniDropAppEvent
+	data class UsernameChanged(val value: String) : VniDropAppEvent
+	data object ChooseReceiveFolderClicked : VniDropAppEvent
+	data class ReceiveFolderPicked(val folder: ReceiveFolder) : VniDropAppEvent
+	data class ReceiveFolderPickFailed(val reason: String) : VniDropAppEvent
+	data object ResetReceiveFolderClicked : VniDropAppEvent
 	data object SelectFileClicked : VniDropAppEvent
 	data class ShareFilePicked(val file: PickedShareFile) : VniDropAppEvent
 	data class ShareFilePickFailed(val reason: String) : VniDropAppEvent
@@ -48,16 +61,18 @@ sealed interface VniDropAppEvent {
 
 sealed interface VniDropAppEffect {
 	data object OpenShareFilePicker : VniDropAppEffect
+	data object OpenReceiveFolderPicker : VniDropAppEffect
 	data class CopyTicket(val ticket: String) : VniDropAppEffect
 }
 
 class VniDropAppViewModel(
 	appDataDir: String,
-	defaultReceiveDir: String,
 	platformName: String,
+	private val preferencesRepository: AppPreferencesRepository,
+	private val fileSystemService: FileSystemService,
 	private val repository: CoreRepository = CoreRepository(),
 ) : ViewModel() {
-	private val _state = MutableStateFlow(VniDropAppState(receive = ReceiveUiState(outputDirectory = defaultReceiveDir)))
+	private val _state = MutableStateFlow(VniDropAppState())
 	val state: StateFlow<VniDropAppState> = _state
 	val coreState: StateFlow<CoreUiState> = repository.state
 
@@ -73,12 +88,23 @@ class VniDropAppViewModel(
 		viewModelScope.launch {
 			repository.initialize(appDataDir)
 		}
+		viewModelScope.launch {
+			preferencesRepository.preferences.collect { preferences ->
+				applyPreferences(preferences)
+				validateReceiveFolder(preferences.receiveFolder)
+			}
+		}
 	}
 
 	fun onEvent(event: VniDropAppEvent) {
 		when (event) {
 			is VniDropAppEvent.DestinationSelected -> updateAppState { copy(destination = event.destination) }
 			is VniDropAppEvent.ThemeModeChanged -> setThemeMode(event.mode)
+			is VniDropAppEvent.UsernameChanged -> setUsername(event.value)
+			VniDropAppEvent.ChooseReceiveFolderClicked -> sendEffect(VniDropAppEffect.OpenReceiveFolderPicker)
+			is VniDropAppEvent.ReceiveFolderPicked -> setReceiveFolder(event.folder)
+			is VniDropAppEvent.ReceiveFolderPickFailed -> setFilePickerError(event.reason)
+			VniDropAppEvent.ResetReceiveFolderClicked -> resetReceiveFolder()
 			VniDropAppEvent.SelectFileClicked -> sendEffect(VniDropAppEffect.OpenShareFilePicker)
 			is VniDropAppEvent.ShareFilePicked -> setSelectedFile(event.file)
 			is VniDropAppEvent.ShareFilePickFailed -> setFilePickerError(event.reason)
@@ -101,6 +127,27 @@ class VniDropAppViewModel(
 	private fun setThemeMode(mode: ThemeMode) {
 		AppLogger.info("appearance", "theme mode changed", mapOf("mode" to mode.name))
 		updateAppState { copy(themeMode = mode) }
+		viewModelScope.launch {
+			preferencesRepository.setThemeMode(mode)
+		}
+	}
+
+	private fun setUsername(username: String) {
+		viewModelScope.launch {
+			preferencesRepository.setUsername(username)
+		}
+	}
+
+	private fun setReceiveFolder(folder: ReceiveFolder) {
+		viewModelScope.launch {
+			preferencesRepository.setReceiveFolder(folder)
+		}
+	}
+
+	private fun resetReceiveFolder() {
+		viewModelScope.launch {
+			preferencesRepository.resetReceiveFolder()
+		}
 	}
 
 	private fun setSelectedFile(file: PickedShareFile) {
@@ -179,19 +226,72 @@ class VniDropAppViewModel(
 
 	private fun receive() {
 		val receiveState = state.value.receive
-		if (!receiveState.canReceive(coreState.value.isInitialized)) return
+		val preferences = state.value.preferences
+		if (!receiveState.canReceive(coreState.value.isInitialized) || !preferences.canReceiveIntoFolder) return
 
 		viewModelScope.launch {
 			AppLogger.info("receive", "receive requested")
 			updateReceiveState { copy(isReceiving = true) }
 			try {
-				repository.receive(receiveState.ticket, receiveState.outputDirectory, receiveState.receiverName)
+				receiveIntoFolder(receiveState, preferences.receiveFolder)
 			} finally {
 				updateReceiveState { copy(isReceiving = false) }
 			}
 		}
 	}
 
+	private suspend fun receiveIntoFolder(receiveState: ReceiveUiState, folder: ReceiveFolder) {
+		val outputSink = fileSystemService.createReceiveOutputSink(folder)
+		when {
+			outputSink != null -> repository.receiveWithOutputSink(receiveState.ticket, outputSink, receiveState.receiverName)
+			folder.kind == ReceiveFolderKind.IosSecurityScopedUrl -> {
+				repository.receiveIntoSecurityScopedDirectory(receiveState.ticket, folder.value, receiveState.receiverName)
+			}
+			else -> repository.receive(receiveState.ticket, folder.value, receiveState.receiverName)
+		}
+	}
+
+	private fun applyPreferences(preferences: AppPreferences) {
+		_state.update { current ->
+			val previousUsername = current.preferences.username
+			current.copy(
+				app = current.app.copy(themeMode = preferences.themeMode),
+				preferences = current.preferences.copy(
+					username = preferences.username,
+					receiveFolder = preferences.receiveFolder,
+				),
+				send = current.send.withDefaultName(
+					currentValue = current.send.senderName,
+					previousDefault = previousUsername,
+					nextDefault = preferences.username,
+					update = { copy(senderName = it) },
+				),
+				receive = current.receive
+					.withDefaultName(
+						currentValue = current.receive.receiverName,
+						previousDefault = previousUsername,
+						nextDefault = preferences.username,
+						update = { copy(receiverName = it) },
+					)
+					.copy(outputDirectory = preferences.receiveFolder.value),
+			)
+		}
+	}
+
+	private suspend fun validateReceiveFolder(folder: ReceiveFolder) {
+		updatePreferencesState { copy(isValidatingFolder = true) }
+		val status = fileSystemService.validateReceiveFolder(folder)
+		updatePreferencesState {
+			copy(
+				folderAccessStatus = status,
+				isValidatingFolder = false,
+			)
+		}
+		if (status != FolderAccessStatus.Writable) {
+			repository.setError("Receive folder is not writable.")
+		}
+	}
+
 	private fun sendEffect(effect: VniDropAppEffect) {
 		viewModelScope.launch {
 			effects.send(effect)
@@ -218,8 +318,27 @@ class VniDropAppViewModel(
 			if (next == current.receive) current else current.copy(receive = next)
 		}
 	}
+
+	private fun updatePreferencesState(reducer: PreferencesUiState.() -> PreferencesUiState) {
+		_state.update { current ->
+			val next = current.preferences.reducer()
+			if (next == current.preferences) current else current.copy(preferences = next)
+		}
+	}
 }
 
+private fun <T> T.withDefaultName(
+	currentValue: String,
+	previousDefault: String,
+	nextDefault: String,
+	update: T.(String) -> T,
+): T =
+	if (currentValue.isBlank() || currentValue == previousDefault) {
+		update(nextDefault)
+	} else {
+		this
+	}
+
 private fun SendUiState.withSelectedFile(file: PickedShareFile): SendUiState =
 	copy(
 		selectedSource = file.value,

shared/src/commonMain/kotlin/com/vnidrop/app/core/CoreRepository.kt

@@ -11,6 +11,7 @@ import kotlin.random.Random
 import uniffi.vnidrop.CoreEvent
 import uniffi.vnidrop.CoreEventSink
 import uniffi.vnidrop.ReceiverRequest
+import uniffi.vnidrop.ReceiveOutputSink
 import uniffi.vnidrop.ShareMetadataInput
 import uniffi.vnidrop.ShareResult
 import uniffi.vnidrop.ShareSource
@@ -126,6 +127,12 @@ class CoreRepository(
 		loadTransfers()
 	}
 
+	suspend fun receiveWithOutputSink(ticket: String, outputSink: ReceiveOutputSink, receiverName: String) = runCore {
+		requireCore().receiveWithOutputSink(ticket, outputSink, receiverName.ifBlank { null })
+		refreshStatus()
+		loadTransfers()
+	}
+
 	suspend fun receiveIntoSecurityScopedDirectory(
 		ticket: String,
 		outputDirectoryUrl: String,

shared/src/commonMain/kotlin/com/vnidrop/app/core/FilePicker.kt

@@ -11,12 +11,22 @@ interface ShareFilePicker {
 	fun pickFile()
 }
 
+interface ReceiveFolderPicker {
+	fun pickFolder()
+}
+
 @Composable
 expect fun rememberShareFilePicker(
 	onFilePicked: (PickedShareFile) -> Unit,
 	onError: (String) -> Unit,
 ): ShareFilePicker
 
+@Composable
+expect fun rememberReceiveFolderPicker(
+	onFolderPicked: (ReceiveFolder) -> Unit,
+	onError: (String) -> Unit,
+): ReceiveFolderPicker
+
 expect suspend fun sharePickedFile(
 	repository: CoreRepository,
 	file: PickedShareFile,

shared/src/commonMain/kotlin/com/vnidrop/app/core/FileSystemService.kt

@@ -0,0 +1,34 @@
+package com.vnidrop.app.core
+
+import androidx.compose.runtime.Composable
+import uniffi.vnidrop.ReceiveOutputSink
+
+enum class ReceiveFolderKind {
+	FileSystemPath,
+	AndroidTreeUri,
+	IosSecurityScopedUrl,
+}
+
+data class ReceiveFolder(
+	val kind: ReceiveFolderKind,
+	val value: String,
+	val displayName: String,
+)
+
+enum class FolderAccessStatus {
+	Writable,
+	PermissionRequired,
+	Unavailable,
+}
+
+interface FileSystemService {
+	fun defaultReceiveFolder(): ReceiveFolder
+	suspend fun validateReceiveFolder(folder: ReceiveFolder): FolderAccessStatus
+	fun createReceiveOutputSink(folder: ReceiveFolder): ReceiveOutputSink?
+}
+
+@Composable
+expect fun rememberFileSystemService(): FileSystemService
+
+fun ReceiveFolder.isFileSystemPath(): Boolean =
+	kind == ReceiveFolderKind.FileSystemPath

shared/src/commonMain/kotlin/com/vnidrop/app/preferences/AppPreferencesRepository.kt

@@ -0,0 +1,94 @@
+package com.vnidrop.app.preferences
+
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.emptyPreferences
+import androidx.datastore.preferences.core.stringPreferencesKey
+import com.vnidrop.app.core.ReceiveFolder
+import com.vnidrop.app.core.ReceiveFolderKind
+import com.vnidrop.app.ui.theme.ThemeMode
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.map
+import okio.Path.Companion.toPath
+
+data class AppPreferences(
+	val username: String,
+	val receiveFolder: ReceiveFolder,
+	val themeMode: ThemeMode,
+)
+
+class AppPreferencesDefaults(
+	val username: String,
+	val receiveFolder: ReceiveFolder,
+	val themeMode: ThemeMode,
+)
+
+class AppPreferencesRepository(
+	private val dataStore: DataStore<Preferences>,
+	private val defaults: AppPreferencesDefaults,
+) {
+	val preferences: Flow<AppPreferences> = dataStore.data
+		.catch { emit(emptyPreferences()) }
+		.map { prefs ->
+			AppPreferences(
+				username = prefs[PreferenceKeys.Username]?.takeIf { it.isNotBlank() } ?: defaults.username,
+				receiveFolder = ReceiveFolder(
+					kind = prefs[PreferenceKeys.ReceiveFolderKind]?.let { receiveFolderKindOrNull(it) }
+						?: defaults.receiveFolder.kind,
+					value = prefs[PreferenceKeys.ReceiveFolderValue]?.takeIf { it.isNotBlank() }
+						?: defaults.receiveFolder.value,
+					displayName = prefs[PreferenceKeys.ReceiveFolderDisplayName]?.takeIf { it.isNotBlank() }
+						?: defaults.receiveFolder.displayName,
+				),
+				themeMode = prefs[PreferenceKeys.ThemeMode]?.let { themeModeOrNull(it) } ?: defaults.themeMode,
+			)
+		}
+
+	suspend fun setUsername(username: String) {
+		dataStore.edit { prefs ->
+			prefs[PreferenceKeys.Username] = username.trim()
+		}
+	}
+
+	suspend fun setReceiveFolder(folder: ReceiveFolder) {
+		dataStore.edit { prefs ->
+			prefs[PreferenceKeys.ReceiveFolderKind] = folder.kind.name
+			prefs[PreferenceKeys.ReceiveFolderValue] = folder.value
+			prefs[PreferenceKeys.ReceiveFolderDisplayName] = folder.displayName
+		}
+	}
+
+	suspend fun resetReceiveFolder() {
+		setReceiveFolder(defaults.receiveFolder)
+	}
+
+	suspend fun setThemeMode(mode: ThemeMode) {
+		dataStore.edit { prefs ->
+			prefs[PreferenceKeys.ThemeMode] = mode.name
+		}
+	}
+}
+
+fun createAppPreferencesDataStore(appDataDir: String): DataStore<Preferences> =
+	PreferenceDataStoreFactory.createWithPath(
+		produceFile = { "$appDataDir/$AppPreferencesFileName".toPath() },
+	)
+
+private object PreferenceKeys {
+	val Username = stringPreferencesKey("username")
+	val ReceiveFolderKind = stringPreferencesKey("receive_folder_kind")
+	val ReceiveFolderValue = stringPreferencesKey("receive_folder_value")
+	val ReceiveFolderDisplayName = stringPreferencesKey("receive_folder_display_name")
+	val ThemeMode = stringPreferencesKey("theme_mode")
+}
+
+private fun receiveFolderKindOrNull(raw: String): ReceiveFolderKind? =
+	runCatching { ReceiveFolderKind.valueOf(raw) }.getOrNull()
+
+private fun themeModeOrNull(raw: String): ThemeMode? =
+	runCatching { ThemeMode.valueOf(raw) }.getOrNull()
+
+private const val AppPreferencesFileName = "app_preferences.preferences_pb"

shared/src/commonMain/kotlin/com/vnidrop/app/ui/screens/ReceiveScreen.kt

@@ -7,10 +7,13 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.unit.dp
 import com.vnidrop.app.VniDropAppEvent
 import com.vnidrop.app.core.CoreUiState
+import com.vnidrop.app.core.FolderAccessStatus
 import com.vnidrop.app.ui.components.AppCard
 import com.vnidrop.app.ui.components.Field
+import com.vnidrop.app.ui.components.MetadataRow
 import com.vnidrop.app.ui.components.PrimaryButton
 import com.vnidrop.app.ui.components.SecondaryButton
+import com.vnidrop.app.ui.state.PreferencesUiState
 import com.vnidrop.app.ui.state.ReceiveUiState
 import org.jetbrains.compose.resources.stringResource
 import vnidrop.shared.generated.resources.Res
@@ -20,6 +23,11 @@ import vnidrop.shared.generated.resources.button_receiving
 import vnidrop.shared.generated.resources.field_output_directory
 import vnidrop.shared.generated.resources.field_receiver_name
 import vnidrop.shared.generated.resources.field_ticket
+import vnidrop.shared.generated.resources.folder_status_permission_required
+import vnidrop.shared.generated.resources.folder_status_unavailable
+import vnidrop.shared.generated.resources.folder_status_validating
+import vnidrop.shared.generated.resources.folder_status_writable
+import vnidrop.shared.generated.resources.metadata_status
 import vnidrop.shared.generated.resources.receive_subtitle
 import vnidrop.shared.generated.resources.receive_title
 import vnidrop.shared.generated.resources.ticket_card_title
@@ -28,6 +36,7 @@ import vnidrop.shared.generated.resources.ticket_card_title
 fun ReceiveScreen(
 	coreState: CoreUiState,
 	receiveState: ReceiveUiState,
+	preferencesState: PreferencesUiState,
 	onEvent: (VniDropAppEvent) -> Unit,
 ) {
 	Column(verticalArrangement = Arrangement.spacedBy(14.dp)) {
@@ -40,10 +49,13 @@ fun ReceiveScreen(
 				label = stringResource(Res.string.field_ticket),
 				minLines = 4,
 			)
-			Field(
-				value = receiveState.outputDirectory,
-				onValueChange = { onEvent(VniDropAppEvent.OutputDirectoryChanged(it)) },
+			MetadataRow(
 				label = stringResource(Res.string.field_output_directory),
+				value = preferencesState.receiveFolder.displayName.ifBlank { preferencesState.receiveFolder.value },
+			)
+			MetadataRow(
+				label = stringResource(Res.string.metadata_status),
+				value = preferencesState.folderAccessStatus.displayName(preferencesState.isValidatingFolder),
 			)
 			Field(
 				value = receiveState.receiverName,
@@ -59,7 +71,7 @@ fun ReceiveScreen(
 				PrimaryButton(
 					text = if (receiveState.isReceiving) stringResource(Res.string.button_receiving) else stringResource(Res.string.button_receive),
 					onClick = { onEvent(VniDropAppEvent.ReceiveClicked) },
-					enabled = receiveState.canReceive(coreState.isInitialized),
+					enabled = receiveState.canReceive(coreState.isInitialized) && preferencesState.canReceiveIntoFolder,
 				)
 			}
 		}
@@ -67,3 +79,15 @@ fun ReceiveScreen(
 		ProgressSection(coreState)
 	}
 }
+
+@Composable
+private fun FolderAccessStatus.displayName(isValidating: Boolean): String =
+	if (isValidating) {
+		stringResource(Res.string.folder_status_validating)
+	} else {
+		when (this) {
+			FolderAccessStatus.Writable -> stringResource(Res.string.folder_status_writable)
+			FolderAccessStatus.PermissionRequired -> stringResource(Res.string.folder_status_permission_required)
+			FolderAccessStatus.Unavailable -> stringResource(Res.string.folder_status_unavailable)
+		}
+	}

shared/src/commonMain/kotlin/com/vnidrop/app/ui/screens/SendEmptyState.kt

@@ -0,0 +1,77 @@
+package com.vnidrop.app.ui.screens
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.heightIn
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.widthIn
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import com.vnidrop.app.core.CoreUiState
+import com.vnidrop.app.ui.components.PrimaryButton
+import com.vnidrop.app.ui.navigation.VniDropIcons
+import com.vnidrop.app.ui.state.SendUiState
+import com.vnidrop.app.ui.state.WindowClass
+import com.vnidrop.app.ui.state.isActiveTransfer
+import com.vnidrop.app.ui.theme.LocalVniDropColors
+import org.jetbrains.compose.resources.stringResource
+import vnidrop.shared.generated.resources.Res
+import vnidrop.shared.generated.resources.button_create_new_transfer
+import vnidrop.shared.generated.resources.send_empty_body
+import vnidrop.shared.generated.resources.send_empty_title
+
+@Composable
+internal fun SendEmptyState(windowClass: WindowClass) {
+	val colors = LocalVniDropColors.current
+	Column(
+		modifier = Modifier
+			.fillMaxWidth()
+			.heightIn(min = if (windowClass == WindowClass.Phone) 540.dp else 420.dp)
+			.padding(horizontal = 24.dp, vertical = 40.dp),
+		horizontalAlignment = Alignment.CenterHorizontally,
+		verticalArrangement = Arrangement.Center,
+	) {
+		Icon(
+			imageVector = VniDropIcons.Send,
+			contentDescription = null,
+			modifier = Modifier.size(96.dp),
+			tint = colors.brandDefault,
+		)
+		Text(
+			text = stringResource(Res.string.send_empty_title),
+			modifier = Modifier.padding(top = 24.dp),
+			style = MaterialTheme.typography.headlineSmall,
+			fontWeight = FontWeight.Bold,
+			textAlign = TextAlign.Center,
+		)
+		Text(
+			text = stringResource(Res.string.send_empty_body),
+			modifier = Modifier
+				.padding(top = 10.dp)
+				.widthIn(max = 520.dp),
+			color = colors.foregroundLighter,
+			style = MaterialTheme.typography.bodyMedium,
+			textAlign = TextAlign.Center,
+		)
+		PrimaryButton(
+			text = stringResource(Res.string.button_create_new_transfer),
+			onClick = {},
+			modifier = Modifier.padding(top = 24.dp),
+		)
+	}
+}
+
+internal fun SendUiState.shouldShowEmptyState(coreState: CoreUiState): Boolean =
+	!hasSelectedSource &&
+		!isSharing &&
+		coreState.lastShare == null &&
+		coreState.transfers.none { it.direction == "send" && it.isActiveTransfer() }

shared/src/commonMain/kotlin/com/vnidrop/app/ui/screens/SendScreen.kt

@@ -17,6 +17,7 @@ import com.vnidrop.app.ui.components.PrimaryButton
 import com.vnidrop.app.ui.components.SecondaryButton
 import com.vnidrop.app.ui.components.StatusPill
 import com.vnidrop.app.ui.state.SendUiState
+import com.vnidrop.app.ui.state.WindowClass
 import com.vnidrop.app.ui.state.formatBytes
 import org.jetbrains.compose.resources.stringResource
 import uniffi.vnidrop.ReceiverRequest
@@ -25,8 +26,8 @@ import vnidrop.shared.generated.resources.Res
 import vnidrop.shared.generated.resources.button_approve
 import vnidrop.shared.generated.resources.button_clear
 import vnidrop.shared.generated.resources.button_copy
-import vnidrop.shared.generated.resources.button_create_share_ticket
-import vnidrop.shared.generated.resources.button_creating_ticket
+import vnidrop.shared.generated.resources.button_create_share
+import vnidrop.shared.generated.resources.button_creating_share
 import vnidrop.shared.generated.resources.button_refresh
 import vnidrop.shared.generated.resources.button_refuse
 import vnidrop.shared.generated.resources.button_select_file
@@ -41,7 +42,7 @@ import vnidrop.shared.generated.resources.receiver_requests_title
 import vnidrop.shared.generated.resources.send_source_empty
 import vnidrop.shared.generated.resources.send_subtitle
 import vnidrop.shared.generated.resources.send_title
-import vnidrop.shared.generated.resources.share_ticket_title
+import vnidrop.shared.generated.resources.share_details_title
 import vnidrop.shared.generated.resources.source_title
 import vnidrop.shared.generated.resources.transfer_details_title
 
@@ -49,28 +50,35 @@ import vnidrop.shared.generated.resources.transfer_details_title
 fun SendScreen(
 	coreState: CoreUiState,
 	sendState: SendUiState,
+	windowClass: WindowClass,
 	onEvent: (VniDropAppEvent) -> Unit,
 ) {
 	Column(verticalArrangement = Arrangement.spacedBy(14.dp)) {
-		ScreenHeader(stringResource(Res.string.send_title), stringResource(Res.string.send_subtitle))
+		if (!sendState.shouldShowEmptyState(coreState)) {
+			ScreenHeader(stringResource(Res.string.send_title), stringResource(Res.string.send_subtitle))
+		}
 		ErrorSection(coreState)
-		SendSourceCard(
-			sendState = sendState,
-			onEvent = onEvent,
-		)
-		SendDetailsCard(
-			coreState = coreState,
-			sendState = sendState,
-			onEvent = onEvent,
-		)
-		coreState.lastShare?.let { share ->
-			ShareResultCard(
-				share = share,
-				requests = coreState.receiverRequests,
+		if (sendState.shouldShowEmptyState(coreState)) {
+			SendEmptyState(windowClass = windowClass)
+		} else {
+			SendSourceCard(
+				sendState = sendState,
 				onEvent = onEvent,
 			)
+			SendDetailsCard(
+				coreState = coreState,
+				sendState = sendState,
+				onEvent = onEvent,
+			)
+			coreState.lastShare?.let { share ->
+				ShareResultCard(
+					share = share,
+					requests = coreState.receiverRequests,
+					onEvent = onEvent,
+				)
+			}
+			ProgressSection(coreState)
 		}
-		ProgressSection(coreState)
 	}
 }
 
@@ -118,7 +126,7 @@ private fun SendDetailsCard(
 			label = stringResource(Res.string.field_sender_name),
 		)
 		PrimaryButton(
-			text = if (sendState.isSharing) stringResource(Res.string.button_creating_ticket) else stringResource(Res.string.button_create_share_ticket),
+			text = if (sendState.isSharing) stringResource(Res.string.button_creating_share) else stringResource(Res.string.button_create_share),
 			onClick = { onEvent(VniDropAppEvent.CreateShareClicked) },
 			enabled = sendState.canCreateShare(coreState.isInitialized),
 		)
@@ -131,7 +139,7 @@ private fun ShareResultCard(
 	requests: List<ReceiverRequest>,
 	onEvent: (VniDropAppEvent) -> Unit,
 ) {
-	AppCard(title = stringResource(Res.string.share_ticket_title), trailing = {
+	AppCard(title = stringResource(Res.string.share_details_title), trailing = {
 		StatusPill("${share.fileCount} file${if (share.fileCount == 1UL) "" else "s"}", tone = PillTone.Brand)
 	}) {
 		MetadataRow(stringResource(Res.string.metadata_transfer), share.transferName)

shared/src/commonMain/kotlin/com/vnidrop/app/ui/screens/SettingsScreen.kt

@@ -39,7 +39,13 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import com.vnidrop.app.DeviceInfo
+import com.vnidrop.app.VniDropAppEvent
 import com.vnidrop.app.core.CoreUiState
+import com.vnidrop.app.core.FolderAccessStatus
+import com.vnidrop.app.ui.components.Field
+import com.vnidrop.app.ui.components.PrimaryButton
+import com.vnidrop.app.ui.components.SecondaryButton
+import com.vnidrop.app.ui.state.PreferencesUiState
 import com.vnidrop.app.ui.state.WindowClass
 import com.vnidrop.app.ui.theme.LocalVniDropColors
 import com.vnidrop.app.ui.theme.ThemeMode
@@ -55,9 +61,18 @@ import vnidrop.shared.generated.resources.appearance_mode_title
 import vnidrop.shared.generated.resources.appearance_system_mode
 import vnidrop.shared.generated.resources.appearance_title
 import vnidrop.shared.generated.resources.battery_level_title
+import vnidrop.shared.generated.resources.button_choose_folder
 import vnidrop.shared.generated.resources.core_status_ready
 import vnidrop.shared.generated.resources.device_model_title
 import vnidrop.shared.generated.resources.device_name_title
+import vnidrop.shared.generated.resources.folder_status_permission_required
+import vnidrop.shared.generated.resources.folder_status_unavailable
+import vnidrop.shared.generated.resources.folder_status_validating
+import vnidrop.shared.generated.resources.folder_status_writable
+import vnidrop.shared.generated.resources.preferences_receive_folder_title
+import vnidrop.shared.generated.resources.preferences_title
+import vnidrop.shared.generated.resources.button_reset_default
+import vnidrop.shared.generated.resources.field_username
 import vnidrop.shared.generated.resources.network_title
 import vnidrop.shared.generated.resources.node_title
 import vnidrop.shared.generated.resources.not_initialized
@@ -68,6 +83,7 @@ import vnidrop.shared.generated.resources.version_title
 
 private enum class SettingsPane {
 	Overview,
+	Preferences,
 	Appearance,
 	About,
 }
@@ -77,8 +93,9 @@ fun SettingsScreen(
 	deviceInfo: DeviceInfo,
 	coreState: CoreUiState,
 	themeMode: ThemeMode,
+	preferencesState: PreferencesUiState,
 	windowClass: WindowClass,
-	onThemeModeChange: (ThemeMode) -> Unit,
+	onEvent: (VniDropAppEvent) -> Unit,
 ) {
 	var pane by remember { mutableStateOf(SettingsPane.Overview) }
 
@@ -89,7 +106,8 @@ fun SettingsScreen(
 			deviceInfo = deviceInfo,
 			coreState = coreState,
 			themeMode = themeMode,
-			onThemeModeChange = onThemeModeChange,
+			preferencesState = preferencesState,
+			onEvent = onEvent,
 		)
 		else -> MobileSettings(
 			pane = pane,
@@ -97,7 +115,8 @@ fun SettingsScreen(
 			deviceInfo = deviceInfo,
 			coreState = coreState,
 			themeMode = themeMode,
-			onThemeModeChange = onThemeModeChange,
+			preferencesState = preferencesState,
+			onEvent = onEvent,
 		)
 	}
 }
@@ -109,7 +128,8 @@ private fun MobileSettings(
 	deviceInfo: DeviceInfo,
 	coreState: CoreUiState,
 	themeMode: ThemeMode,
-	onThemeModeChange: (ThemeMode) -> Unit,
+	preferencesState: PreferencesUiState,
+	onEvent: (VniDropAppEvent) -> Unit,
 ) {
 	Column(verticalArrangement = Arrangement.spacedBy(16.dp)) {
 		ErrorSection(coreState)
@@ -117,13 +137,21 @@ private fun MobileSettings(
 			SettingsPane.Overview -> SettingsOverview(
 				coreState = coreState,
 				themeMode = themeMode,
+				preferencesState = preferencesState,
+				onOpenPreferences = { onPaneSelected(SettingsPane.Preferences) },
 				onOpenAppearance = { onPaneSelected(SettingsPane.Appearance) },
 				onOpenAbout = { onPaneSelected(SettingsPane.About) },
 				largeTitle = true,
 			)
+			SettingsPane.Preferences -> PreferencesSettings(
+				preferencesState = preferencesState,
+				onEvent = onEvent,
+				onBack = { onPaneSelected(SettingsPane.Overview) },
+				showBack = true,
+			)
 			SettingsPane.Appearance -> AppearanceSettings(
 				themeMode = themeMode,
-				onThemeModeChange = onThemeModeChange,
+				onThemeModeChange = { onEvent(VniDropAppEvent.ThemeModeChanged(it)) },
 				onBack = { onPaneSelected(SettingsPane.Overview) },
 				showBack = true,
 			)
@@ -144,7 +172,8 @@ private fun DesktopSettings(
 	deviceInfo: DeviceInfo,
 	coreState: CoreUiState,
 	themeMode: ThemeMode,
-	onThemeModeChange: (ThemeMode) -> Unit,
+	preferencesState: PreferencesUiState,
+	onEvent: (VniDropAppEvent) -> Unit,
 ) {
 	Row(
 		modifier = Modifier.fillMaxWidth(),
@@ -158,6 +187,8 @@ private fun DesktopSettings(
 			SettingsOverview(
 				coreState = coreState,
 				themeMode = themeMode,
+				preferencesState = preferencesState,
+				onOpenPreferences = { onPaneSelected(SettingsPane.Preferences) },
 				onOpenAppearance = { onPaneSelected(SettingsPane.Appearance) },
 				onOpenAbout = { onPaneSelected(SettingsPane.About) },
 				largeTitle = false,
@@ -170,9 +201,15 @@ private fun DesktopSettings(
 		) {
 			when (selectedPane) {
 				SettingsPane.Overview,
+				SettingsPane.Preferences -> PreferencesSettings(
+					preferencesState = preferencesState,
+					onEvent = onEvent,
+					onBack = {},
+					showBack = false,
+				)
 				SettingsPane.Appearance -> AppearanceSettings(
 					themeMode = themeMode,
-					onThemeModeChange = onThemeModeChange,
+					onThemeModeChange = { onEvent(VniDropAppEvent.ThemeModeChanged(it)) },
 					onBack = {},
 					showBack = false,
 				)
@@ -191,6 +228,8 @@ private fun DesktopSettings(
 private fun SettingsOverview(
 	coreState: CoreUiState,
 	themeMode: ThemeMode,
+	preferencesState: PreferencesUiState,
+	onOpenPreferences: () -> Unit,
 	onOpenAppearance: () -> Unit,
 	onOpenAbout: () -> Unit,
 	largeTitle: Boolean,
@@ -203,6 +242,13 @@ private fun SettingsOverview(
 			Text(stringResource(Res.string.settings_title), style = MaterialTheme.typography.headlineMedium, fontWeight = FontWeight.Bold)
 		}
 		SettingsGroup {
+			SettingsRow(
+				icon = SettingsIcons.Device,
+				title = stringResource(Res.string.preferences_title),
+				value = preferencesState.username,
+				selected = selectedPane == SettingsPane.Preferences,
+				onClick = onOpenPreferences,
+			)
 			SettingsRow(
 				icon = SettingsIcons.Sun,
 				title = stringResource(Res.string.appearance_title),
@@ -228,6 +274,46 @@ private fun SettingsOverview(
 	}
 }
 
+@Composable
+private fun PreferencesSettings(
+	preferencesState: PreferencesUiState,
+	onEvent: (VniDropAppEvent) -> Unit,
+	onBack: () -> Unit,
+	showBack: Boolean,
+) {
+	Column(verticalArrangement = Arrangement.spacedBy(16.dp)) {
+		SettingsTopBar(title = stringResource(Res.string.preferences_title), onBack = onBack, showBack = showBack)
+		Field(
+			value = preferencesState.username,
+			onValueChange = { onEvent(VniDropAppEvent.UsernameChanged(it)) },
+			label = stringResource(Res.string.field_username),
+		)
+		SettingsGroup {
+			SettingsRow(
+				icon = SettingsIcons.Folder,
+				title = stringResource(Res.string.preferences_receive_folder_title),
+				value = preferencesState.receiveFolder.displayName.ifBlank { preferencesState.receiveFolder.value },
+				iconTone = IconTone.Neutral,
+			)
+			SettingsRow(
+				icon = SettingsIcons.Check,
+				title = preferencesState.folderAccessStatus.displayName(isValidating = preferencesState.isValidatingFolder),
+				iconTone = IconTone.Neutral,
+			)
+		}
+		Row(horizontalArrangement = Arrangement.spacedBy(10.dp)) {
+			PrimaryButton(
+				text = stringResource(Res.string.button_choose_folder),
+				onClick = { onEvent(VniDropAppEvent.ChooseReceiveFolderClicked) },
+			)
+			SecondaryButton(
+				text = stringResource(Res.string.button_reset_default),
+				onClick = { onEvent(VniDropAppEvent.ResetReceiveFolderClicked) },
+			)
+		}
+	}
+}
+
 @Composable
 private fun AppearanceSettings(
 	themeMode: ThemeMode,
@@ -479,6 +565,18 @@ private fun ThemeMode.displayName(): String =
 		ThemeMode.Dark -> stringResource(Res.string.appearance_dark_mode)
 	}
 
+@Composable
+private fun FolderAccessStatus.displayName(isValidating: Boolean): String =
+	if (isValidating) {
+		stringResource(Res.string.folder_status_validating)
+	} else {
+		when (this) {
+			FolderAccessStatus.Writable -> stringResource(Res.string.folder_status_writable)
+			FolderAccessStatus.PermissionRequired -> stringResource(Res.string.folder_status_permission_required)
+			FolderAccessStatus.Unavailable -> stringResource(Res.string.folder_status_unavailable)
+		}
+	}
+
 private enum class IconTone {
 	Brand,
 	Neutral,
@@ -533,6 +631,15 @@ private object SettingsIcons {
 		moveTo(11f, 18f)
 		lineTo(13f, 18f)
 	}
+	val Folder = lineIcon("Folder") {
+		moveTo(3f, 7f)
+		lineTo(9f, 7f)
+		lineTo(11f, 9f)
+		lineTo(21f, 9f)
+		lineTo(21f, 19f)
+		lineTo(3f, 19f)
+		close()
+	}
 	val Info = lineIcon("Info") {
 		moveTo(12f, 16f)
 		lineTo(12f, 12f)

shared/src/commonMain/kotlin/com/vnidrop/app/ui/state/AppUiModels.kt

@@ -2,6 +2,9 @@ package com.vnidrop.app.ui.state
 
 import com.vnidrop.app.ui.theme.ThemeMode
 import com.vnidrop.app.ui.navigation.AppDestination
+import com.vnidrop.app.core.FolderAccessStatus
+import com.vnidrop.app.core.ReceiveFolder
+import com.vnidrop.app.core.ReceiveFolderKind
 import uniffi.vnidrop.CoreEvent
 import uniffi.vnidrop.StoredTransfer
 import kotlin.math.roundToInt
@@ -27,6 +30,20 @@ data class AppUiState(
 	val themeMode: ThemeMode = ThemeMode.System,
 )
 
+data class PreferencesUiState(
+	val username: String = "",
+	val receiveFolder: ReceiveFolder = ReceiveFolder(
+		kind = ReceiveFolderKind.FileSystemPath,
+		value = "",
+		displayName = "",
+	),
+	val folderAccessStatus: FolderAccessStatus = FolderAccessStatus.Unavailable,
+	val isValidatingFolder: Boolean = false,
+) {
+	val canReceiveIntoFolder: Boolean
+		get() = folderAccessStatus == FolderAccessStatus.Writable
+}
+
 data class SendUiState(
 	val selectedSource: String = "",
 	val selectedDisplayName: String = "",
@@ -72,6 +89,9 @@ fun displayNameForStatus(status: String): String =
 		else -> status.replaceFirstChar { it.uppercase() }
 	}
 
+fun StoredTransfer.isActiveTransfer(): Boolean =
+	status.lowercase() in activeTransferStatuses
+
 fun summarizeProgress(events: List<CoreEvent>): List<TransferProgress> =
 	events
 		.filter { event -> event.transferId != null && event.phase in progressPhases }
@@ -123,6 +143,7 @@ fun friendlyCoreError(raw: String?): String? {
 }
 
 private val progressPhases = setOf("import", "ticket", "access", "transfer", "download", "export", "lifecycle")
+private val activeTransferStatuses = setOf("sharing", "receiving")
 
 private fun eventLabel(event: CoreEvent): String {
 	val direction = event.direction?.replaceFirstChar { it.uppercase() }