Add configurable data location (portable/system)

Introduce support for choosing and resolving the application's data root (system user dir vs. portable app folder). Adds DataLocationConfig model, DataLocationResolver (load/save/resolve/migrate), a UI prompt (DataLocationPromptWindow) and an OOBE step (DataLocationOobeStep) to let users pick and optionally migrate existing data. Wire the chosen data root into the launcher flow and host launch plan (forwarded via --data-root and LMD_DATA_ROOT), and add AppDataPathProvider to let runtime services read the effective data root (initialized in Program.Main). Update various services (logging, settings, DB, plugin/market, startup registry, etc.) to use the new provider/resolver and register the config type in the JSON context. This enables portable installs, safe migration, and runtime overrides via CLI or environment variable.

LanMountainDesktop.Launcher/AppJsonContext.cs

@@ -34,6 +34,7 @@ namespace LanMountainDesktop.Launcher;
 [JsonSerializable(typeof(PendingUpgrade))]
 [JsonSerializable(typeof(List<PendingUpgrade>))]
 [JsonSerializable(typeof(OobeStateFile))]
+[JsonSerializable(typeof(DataLocationConfig))]
 [JsonSerializable(typeof(GitHubRelease))]
 [JsonSerializable(typeof(GitHubAsset))]
 [JsonSerializable(typeof(List<GitHubRelease>))]

LanMountainDesktop.Launcher/Models/DataLocationModels.cs

@@ -0,0 +1,23 @@
+namespace LanMountainDesktop.Launcher.Models;
+
+internal enum DataLocationMode
+{
+    System,
+    Portable
+}
+
+internal sealed class DataLocationConfig
+{
+    public string DataLocationMode { get; set; } = "System";
+
+    public string? SystemDataPath { get; set; }
+
+    public string? PortableDataPath { get; set; }
+}
+
+internal sealed class DataLocationPromptResult
+{
+    public DataLocationMode SelectedMode { get; init; }
+
+    public bool MigrateExistingData { get; init; }
+}

LanMountainDesktop.Launcher/Services/DataLocationOobeStep.cs

@@ -0,0 +1,67 @@
+using Avalonia.Threading;
+using LanMountainDesktop.Launcher.Models;
+using LanMountainDesktop.Launcher.Views;
+
+namespace LanMountainDesktop.Launcher.Services;
+
+internal sealed class DataLocationOobeStep : IOobeStep
+{
+    private readonly DataLocationResolver _resolver;
+
+    public DataLocationOobeStep(DataLocationResolver resolver)
+    {
+        _resolver = resolver;
+    }
+
+    public async Task RunAsync(CancellationToken cancellationToken)
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+
+        var existingConfig = _resolver.LoadConfig();
+        if (existingConfig is not null)
+        {
+            Logger.Info("DataLocation OOBE step skipped: config already exists.");
+            return;
+        }
+
+        DataLocationPromptWindow? window = null;
+        await Dispatcher.UIThread.InvokeAsync(() =>
+        {
+            window = new DataLocationPromptWindow(_resolver);
+            window.Show();
+        });
+
+        if (window is null)
+        {
+            Logger.Warn("DataLocation OOBE step failed: window could not be created.");
+            return;
+        }
+
+        try
+        {
+            var result = await window.WaitForChoiceAsync().ConfigureAwait(false);
+            if (result is null)
+            {
+                Logger.Info("DataLocation OOBE step: user cancelled or closed window. Using default system location.");
+                _resolver.ApplyLocationChoice(DataLocationMode.System, false);
+            }
+            else
+            {
+                var success = _resolver.ApplyLocationChoice(result.SelectedMode, result.MigrateExistingData);
+                Logger.Info(
+                    $"DataLocation OOBE step: user selected '{result.SelectedMode}'. " +
+                    $"Migrate={result.MigrateExistingData}; Success={success}.");
+            }
+        }
+        finally
+        {
+            await Dispatcher.UIThread.InvokeAsync(() =>
+            {
+                if (window.IsVisible)
+                {
+                    window.Close();
+                }
+            });
+        }
+    }
+}

LanMountainDesktop.Launcher/Services/DataLocationResolver.cs

@@ -0,0 +1,244 @@
+using System.Text.Json;
+using LanMountainDesktop.Launcher.Models;
+
+namespace LanMountainDesktop.Launcher.Services;
+
+internal sealed class DataLocationResolver
+{
+    private const string ConfigFileName = "data-location.config.json";
+    private const string PortableDataFolderName = "AppData";
+
+    private readonly string _appRoot;
+    private readonly string _configPath;
+    private readonly string _defaultSystemDataPath;
+
+    public DataLocationResolver(string appRoot)
+    {
+        _appRoot = Path.GetFullPath(appRoot);
+        _configPath = Path.Combine(_appRoot, ConfigFileName);
+        _defaultSystemDataPath = Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+            "LanMountainDesktop");
+    }
+
+    public string AppRoot => _appRoot;
+
+    public string ConfigPath => _configPath;
+
+    public string DefaultSystemDataPath => _defaultSystemDataPath;
+
+    public string DefaultPortableDataPath => Path.Combine(_appRoot, PortableDataFolderName);
+
+    public bool IsPortableModeAllowed()
+    {
+        try
+        {
+            var testFile = Path.Combine(_appRoot, $".write-test-{Guid.NewGuid():N}.tmp");
+            File.WriteAllText(testFile, string.Empty);
+            File.Delete(testFile);
+            return true;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    public DataLocationConfig? LoadConfig()
+    {
+        try
+        {
+            if (!File.Exists(_configPath))
+            {
+                return null;
+            }
+
+            var json = File.ReadAllText(_configPath);
+            return JsonSerializer.Deserialize(json, AppJsonContext.Default.DataLocationConfig);
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Failed to load data location config from '{_configPath}'. Error='{ex.Message}'.");
+            return null;
+        }
+    }
+
+    public bool SaveConfig(DataLocationConfig config)
+    {
+        try
+        {
+            var json = JsonSerializer.Serialize(config, AppJsonContext.Default.DataLocationConfig);
+            File.WriteAllText(_configPath, json);
+            return true;
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Failed to save data location config to '{_configPath}'. Error='{ex.Message}'.");
+            return false;
+        }
+    }
+
+    public string ResolveDataRoot()
+    {
+        var config = LoadConfig();
+        if (config is null)
+        {
+            return _defaultSystemDataPath;
+        }
+
+        if (string.Equals(config.DataLocationMode, "Portable", StringComparison.OrdinalIgnoreCase))
+        {
+            var portablePath = !string.IsNullOrWhiteSpace(config.PortableDataPath)
+                ? config.PortableDataPath
+                : DefaultPortableDataPath;
+            return Path.GetFullPath(portablePath);
+        }
+
+        return !string.IsNullOrWhiteSpace(config.SystemDataPath)
+            ? Path.GetFullPath(config.SystemDataPath)
+            : _defaultSystemDataPath;
+    }
+
+    public DataLocationMode ResolveMode()
+    {
+        var config = LoadConfig();
+        if (config is null)
+        {
+            return DataLocationMode.System;
+        }
+
+        return string.Equals(config.DataLocationMode, "Portable", StringComparison.OrdinalIgnoreCase)
+            ? DataLocationMode.Portable
+            : DataLocationMode.System;
+    }
+
+    public bool HasExistingSystemData()
+    {
+        var systemPath = _defaultSystemDataPath;
+        if (!Directory.Exists(systemPath))
+        {
+            return false;
+        }
+
+        var markerFiles = new[]
+        {
+            Path.Combine(systemPath, "settings.json"),
+            Path.Combine(systemPath, "launcher-settings.json"),
+            Path.Combine(systemPath, "component-state.db"),
+            Path.Combine(systemPath, "app.db")
+        };
+
+        return markerFiles.Any(File.Exists);
+    }
+
+    public bool ApplyLocationChoice(DataLocationMode mode, bool migrateExistingData)
+    {
+        var config = new DataLocationConfig
+        {
+            DataLocationMode = mode.ToString(),
+            SystemDataPath = _defaultSystemDataPath,
+            PortableDataPath = DefaultPortableDataPath
+        };
+
+        if (!SaveConfig(config))
+        {
+            return false;
+        }
+
+        var targetDataRoot = mode == DataLocationMode.Portable
+            ? DefaultPortableDataPath
+            : _defaultSystemDataPath;
+
+        try
+        {
+            Directory.CreateDirectory(targetDataRoot);
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Failed to create data directory '{targetDataRoot}'. Error='{ex.Message}'.");
+            return false;
+        }
+
+        if (migrateExistingData && mode == DataLocationMode.Portable)
+        {
+            MigrateSystemDataToPortable();
+        }
+
+        return true;
+    }
+
+    private void MigrateSystemDataToPortable()
+    {
+        if (!HasExistingSystemData())
+        {
+            return;
+        }
+
+        var sourcePath = _defaultSystemDataPath;
+        var targetPath = DefaultPortableDataPath;
+
+        try
+        {
+            Directory.CreateDirectory(targetPath);
+
+            var filesToMigrate = Directory.GetFiles(sourcePath, "*", SearchOption.TopDirectoryOnly);
+            foreach (var file in filesToMigrate)
+            {
+                var fileName = Path.GetFileName(file);
+                var destFile = Path.Combine(targetPath, fileName);
+                try
+                {
+                    File.Copy(file, destFile, overwrite: true);
+                }
+                catch (Exception ex)
+                {
+                    Logger.Warn($"Failed to migrate file '{fileName}'. Error='{ex.Message}'.");
+                }
+            }
+
+            var dirsToMigrate = Directory.GetDirectories(sourcePath, "*", SearchOption.TopDirectoryOnly);
+            foreach (var dir in dirsToMigrate)
+            {
+                var dirName = Path.GetFileName(dir);
+                if (string.Equals(dirName, ".launcher", StringComparison.OrdinalIgnoreCase) &&
+                    string.Equals(Path.GetFileName(sourcePath), "LanMountainDesktop", StringComparison.OrdinalIgnoreCase))
+                {
+                    continue;
+                }
+
+                var destDir = Path.Combine(targetPath, dirName);
+                try
+                {
+                    CopyDirectory(dir, destDir);
+                }
+                catch (Exception ex)
+                {
+                    Logger.Warn($"Failed to migrate directory '{dirName}'. Error='{ex.Message}'.");
+                }
+            }
+
+            Logger.Info($"Data migration completed. Source='{sourcePath}'; Target='{targetPath}'.");
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Data migration failed. Source='{sourcePath}'; Target='{targetPath}'. Error='{ex.Message}'.");
+        }
+    }
+
+    private static void CopyDirectory(string sourceDir, string destDir)
+    {
+        Directory.CreateDirectory(destDir);
+
+        foreach (var file in Directory.GetFiles(sourceDir))
+        {
+            var destFile = Path.Combine(destDir, Path.GetFileName(file));
+            File.Copy(file, destFile, overwrite: true);
+        }
+
+        foreach (var subDir in Directory.GetDirectories(sourceDir))
+        {
+            var destSubDir = Path.Combine(destDir, Path.GetFileName(subDir));
+            CopyDirectory(subDir, destSubDir);
+        }
+    }
+}

LanMountainDesktop.Launcher/Services/HostLaunchPlan.cs

@@ -12,10 +12,12 @@ internal sealed record HostLaunchPlan(
 
 internal static class HostLaunchPlanBuilder
 {
+    public const string DataRootOptionName = "data-root";
+
     private static readonly string[] LauncherOnlyOptions =
     [
         "debug", "show-loading-details", "plugins-dir", "source", "result",
-        "app-root",
+        "app-root", DataRootOptionName,
         LauncherIpcConstants.LauncherPidEnvVar,
         LauncherIpcConstants.PackageRootEnvVar,
         LauncherIpcConstants.VersionEnvVar,
@@ -25,7 +27,8 @@ internal static class HostLaunchPlanBuilder
     public static HostLaunchPlan Build(
         CommandContext context,
         DeploymentLocator deploymentLocator,
-        HostResolutionResult resolution)
+        HostResolutionResult resolution,
+        string? dataRoot = null)
     {
         ArgumentNullException.ThrowIfNull(context);
         ArgumentNullException.ThrowIfNull(deploymentLocator);
@@ -39,7 +42,7 @@ internal static class HostLaunchPlanBuilder
         var hostPath = Path.GetFullPath(resolution.ResolvedHostPath);
         var packageRoot = ResolvePackageRoot(hostPath, resolution.AppRoot, resolution.ResolutionSource);
         var versionInfo = deploymentLocator.GetVersionInfo();
-        var arguments = BuildForwardedArguments(context, packageRoot, versionInfo);
+        var arguments = BuildForwardedArguments(context, packageRoot, versionInfo, dataRoot);
         var environment = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
         {
             [LauncherIpcConstants.LauncherPidEnvVar] = Environment.ProcessId.ToString(),
@@ -48,6 +51,11 @@ internal static class HostLaunchPlanBuilder
             [LauncherIpcConstants.CodenameEnvVar] = versionInfo.Codename
         };
 
+        if (!string.IsNullOrWhiteSpace(dataRoot))
+        {
+            environment["LMD_DATA_ROOT"] = dataRoot;
+        }
+
         return new HostLaunchPlan(
             hostPath,
             packageRoot,
@@ -92,7 +100,8 @@ internal static class HostLaunchPlanBuilder
     private static IReadOnlyList<string> BuildForwardedArguments(
         CommandContext context,
         string packageRoot,
-        AppVersionInfo versionInfo)
+        AppVersionInfo versionInfo,
+        string? dataRoot = null)
     {
         var arguments = new List<string>();
 
@@ -144,6 +153,11 @@ internal static class HostLaunchPlanBuilder
         arguments.Add($"--{LauncherIpcConstants.VersionEnvVar}={versionInfo.Version}");
         arguments.Add($"--{LauncherIpcConstants.CodenameEnvVar}={versionInfo.Codename}");
 
+        if (!string.IsNullOrWhiteSpace(dataRoot))
+        {
+            arguments.Add($"--{DataRootOptionName}={dataRoot}");
+        }
+
         return arguments;
     }
 

LanMountainDesktop.Launcher/Services/LauncherDebugSettingsStore.cs

@@ -100,6 +100,16 @@ internal static class LauncherDebugSettingsStore
 
     private static string ResolveConfigBaseDirectory()
     {
+        try
+        {
+            var appRoot = Commands.ResolveAppRoot(CommandContext.FromArgs([]));
+            var resolver = new DataLocationResolver(appRoot);
+            return Path.Combine(resolver.ResolveDataRoot(), ".launcher");
+        }
+        catch
+        {
+        }
+
         try
         {
             var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);

LanMountainDesktop.Launcher/Services/LauncherFlowCoordinator.cs

@@ -23,6 +23,7 @@ internal sealed class LauncherFlowCoordinator
     private readonly PluginInstallerService _pluginInstallerService;
     private readonly StartupAttemptRegistry _startupAttemptRegistry;
     private readonly LauncherCoordinatorIpcServer? _coordinatorIpcServer;
+    private readonly DataLocationResolver _dataLocationResolver;
     private readonly IReadOnlyList<IOobeStep> _oobeSteps;
 
     public LauncherFlowCoordinator(
@@ -41,7 +42,12 @@ internal sealed class LauncherFlowCoordinator
         _pluginInstallerService = pluginInstallerService;
         _startupAttemptRegistry = startupAttemptRegistry ?? new StartupAttemptRegistry();
         _coordinatorIpcServer = coordinatorIpcServer;
-        _oobeSteps = [new WelcomeOobeStep(_oobeStateService, _context)];
+        _dataLocationResolver = new DataLocationResolver(deploymentLocator.GetAppRoot());
+        _oobeSteps =
+        [
+            new WelcomeOobeStep(_oobeStateService, _context),
+            new DataLocationOobeStep(_dataLocationResolver)
+        ];
     }
 
     public static string ResolveSuccessPolicyKey(CommandContext context)
@@ -1025,7 +1031,8 @@ internal sealed class LauncherFlowCoordinator
         bool forceDirectMode,
         string? retryTag)
     {
-        var plan = HostLaunchPlanBuilder.Build(_context, _deploymentLocator, resolution);
+        var dataRoot = _dataLocationResolver.ResolveDataRoot();
+        var plan = HostLaunchPlanBuilder.Build(_context, _deploymentLocator, resolution, dataRoot);
         var hostPath = plan.HostPath;
         if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS())
         {

LanMountainDesktop.Launcher/Services/Logger.cs

@@ -53,6 +53,16 @@ internal static class Logger
     /// </summary>
     private static string? GetLogDirectory()
     {
+        try
+        {
+            var appRoot = Commands.ResolveAppRoot(CommandContext.FromArgs([]));
+            var resolver = new DataLocationResolver(appRoot);
+            return Path.Combine(resolver.ResolveDataRoot(), ".launcher", "logs");
+        }
+        catch
+        {
+        }
+
         try
         {
             var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);

LanMountainDesktop.Launcher/Services/OobeStateService.cs

@@ -21,7 +21,7 @@ internal sealed class OobeStateService
         _executionSnapshot = executionSnapshot ?? LauncherExecutionContext.Capture();
 
         var stateRoot = string.IsNullOrWhiteSpace(stateRootOverride)
-            ? GetDefaultStateRoot()
+            ? ResolveStateRoot(appRoot)
             : Path.GetFullPath(stateRootOverride);
         _stateDirectory = Path.Combine(stateRoot, ".launcher", "state");
         _statePath = Path.Combine(_stateDirectory, "oobe-state.json");
@@ -208,14 +208,22 @@ internal sealed class OobeStateService
         };
     }
 
-    private static string GetDefaultStateRoot()
+    private static string ResolveStateRoot(string appRoot)
     {
-        var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
-        if (string.IsNullOrWhiteSpace(appData))
+        try
         {
-            throw new InvalidOperationException("LocalApplicationData is unavailable.");
+            var resolver = new DataLocationResolver(appRoot);
+            return resolver.ResolveDataRoot();
         }
+        catch
+        {
+            var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
+            if (string.IsNullOrWhiteSpace(appData))
+            {
+                throw new InvalidOperationException("LocalApplicationData is unavailable.");
+            }
 
-        return Path.Combine(appData, "LanMountainDesktop");
+            return Path.Combine(appData, "LanMountainDesktop");
+        }
     }
 }

LanMountainDesktop.Launcher/Services/PluginInstallerService.cs

@@ -63,13 +63,28 @@ internal sealed class PluginInstallerService
             return null;
         }
 
-        var localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
-        if (string.IsNullOrWhiteSpace(localAppData))
+        string? allowedRoot = null;
+        try
+        {
+            var appRoot = Commands.ResolveAppRoot(CommandContext.FromArgs([]));
+            var resolver = new DataLocationResolver(appRoot);
+            allowedRoot = EnsureTrailingSeparator(resolver.ResolveDataRoot());
+        }
+        catch
         {
-            return null;
         }
 
-        var allowedRoot = EnsureTrailingSeparator(Path.Combine(Path.GetFullPath(localAppData), "LanMountainDesktop"));
+        if (string.IsNullOrWhiteSpace(allowedRoot))
+        {
+            var localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
+            if (string.IsNullOrWhiteSpace(localAppData))
+            {
+                return null;
+            }
+
+            allowedRoot = EnsureTrailingSeparator(Path.Combine(Path.GetFullPath(localAppData), "LanMountainDesktop"));
+        }
+
         var normalizedPluginsDirectory = EnsureTrailingSeparator(Path.GetFullPath(pluginsDirectory));
         if (normalizedPluginsDirectory.StartsWith(allowedRoot, StringComparison.OrdinalIgnoreCase))
         {

LanMountainDesktop.Launcher/Services/StartupAttemptRegistry.cs

@@ -20,15 +20,29 @@ internal sealed class StartupAttemptRegistry
     private string? _ownedAttemptId;
 
     public StartupAttemptRegistry()
-        : this(Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
-            "LanMountainDesktop",
-            ".launcher",
-            "state",
-            "startup-attempt.json"))
+        : this(ResolveDefaultStatePath())
     {
     }
 
+    private static string ResolveDefaultStatePath()
+    {
+        try
+        {
+            var appRoot = Commands.ResolveAppRoot(CommandContext.FromArgs([]));
+            var resolver = new DataLocationResolver(appRoot);
+            return Path.Combine(resolver.ResolveDataRoot(), ".launcher", "state", "startup-attempt.json");
+        }
+        catch
+        {
+            return Path.Combine(
+                Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+                "LanMountainDesktop",
+                ".launcher",
+                "state",
+                "startup-attempt.json");
+        }
+    }
+
     internal StartupAttemptRegistry(string statePath)
     {
         _statePath = statePath;

LanMountainDesktop.Launcher/Views/DataLocationPromptWindow.axaml

@@ -0,0 +1,153 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:views="clr-namespace:LanMountainDesktop.Launcher.Views"
+        xmlns:ui="using:FluentAvalonia.UI.Controls"
+        mc:Ignorable="d"
+        d:DesignWidth="520"
+        d:DesignHeight="480"
+        x:Class="LanMountainDesktop.Launcher.Views.DataLocationPromptWindow"
+        x:DataType="views:DataLocationPromptWindow"
+        Title="选择数据保存位置"
+        Width="520"
+        Height="480"
+        CanResize="False"
+        WindowStartupLocation="CenterScreen"
+        Background="{DynamicResource SolidBackgroundFillColorBaseBrush}"
+        TransparencyLevelHint="None"
+        Icon="/Assets/logo.ico">
+  <Grid x:Name="ContentGrid"
+        Opacity="0">
+    <Grid.RenderTransform>
+      <TranslateTransform Y="24" />
+    </Grid.RenderTransform>
+    <Grid Margin="36" RowDefinitions="Auto,*,Auto">
+      <StackPanel Grid.Row="0" Spacing="8" Margin="0,0,0,20">
+        <TextBlock Text="选择数据保存位置"
+                   FontSize="22"
+                   FontWeight="SemiBold"
+                   Foreground="{DynamicResource TextFillColorPrimaryBrush}" />
+        <TextBlock Text="决定将应用数据保存在哪里，可随时在设置中更改"
+                   FontSize="13"
+                   Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+      </StackPanel>
+
+      <StackPanel Grid.Row="1" Spacing="12">
+        <Border x:Name="AdminWarningBanner"
+                Background="{DynamicResource SystemFillColorCriticalBackgroundBrush}"
+                CornerRadius="{DynamicResource DesignCornerRadiusMd}"
+                Padding="12,10"
+                IsVisible="False">
+          <StackPanel Spacing="4">
+            <StackPanel Orientation="Horizontal" Spacing="6">
+              <ui:SymbolIcon Symbol="Important"
+                             FontSize="16"
+                             Foreground="{DynamicResource SystemFillColorCriticalBrush}" />
+              <TextBlock Text="无法保存到应用目录"
+                         FontWeight="SemiBold"
+                         FontSize="13"
+                         Foreground="{DynamicResource SystemFillColorCriticalBrush}" />
+            </StackPanel>
+            <TextBlock Text="当前安装目录需要管理员权限才能写入，数据将自动保存到系统用户目录。"
+                       FontSize="12"
+                       TextWrapping="Wrap"
+                       Foreground="{DynamicResource SystemFillColorCriticalBrush}" />
+          </StackPanel>
+        </Border>
+
+        <Border x:Name="SystemOptionBorder"
+                Background="{DynamicResource CardBackgroundFillColorDefaultBrush}"
+                CornerRadius="{DynamicResource DesignCornerRadiusMd}"
+                BorderThickness="2"
+                BorderBrush="{DynamicResource AccentFillColorDefaultBrush}"
+                Padding="16,14">
+          <Grid ColumnDefinitions="Auto,*">
+            <RadioButton x:Name="SystemRadio"
+                         Grid.Column="0"
+                         VerticalAlignment="Top"
+                         Margin="0,2,12,0"
+                         GroupName="DataLocation"
+                         IsChecked="True" />
+            <StackPanel Grid.Column="1" Spacing="4">
+              <TextBlock Text="保存在系统用户目录（推荐）"
+                         FontSize="14"
+                         FontWeight="SemiBold"
+                         Foreground="{DynamicResource TextFillColorPrimaryBrush}" />
+              <TextBlock Text="数据与当前 Windows 用户绑定，重装应用或更新后数据不会丢失"
+                         FontSize="12"
+                         TextWrapping="Wrap"
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+              <TextBlock x:Name="SystemPathText"
+                         FontSize="11"
+                         TextWrapping="Wrap"
+                         Foreground="{DynamicResource TextFillColorTertiaryBrush}"
+                         Margin="0,4,0,0" />
+            </StackPanel>
+          </Grid>
+        </Border>
+
+        <Border x:Name="PortableOptionBorder"
+                Background="{DynamicResource CardBackgroundFillColorDefaultBrush}"
+                CornerRadius="{DynamicResource DesignCornerRadiusMd}"
+                BorderThickness="1"
+                BorderBrush="{DynamicResource CardStrokeColorDefaultBrush}"
+                Padding="16,14">
+          <Grid ColumnDefinitions="Auto,*">
+            <RadioButton x:Name="PortableRadio"
+                         Grid.Column="0"
+                         VerticalAlignment="Top"
+                         Margin="0,2,12,0"
+                         GroupName="DataLocation"
+                         IsEnabled="False" />
+            <StackPanel Grid.Column="1" Spacing="4">
+              <TextBlock Text="保存在应用安装目录"
+                         FontSize="14"
+                         FontWeight="SemiBold"
+                         Foreground="{DynamicResource TextFillColorPrimaryBrush}" />
+              <TextBlock Text="便于携带，可随应用文件夹整体移动到其他电脑"
+                         FontSize="12"
+                         TextWrapping="Wrap"
+                         Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
+              <TextBlock x:Name="PortablePathText"
+                         FontSize="11"
+                         TextWrapping="Wrap"
+                         Foreground="{DynamicResource TextFillColorTertiaryBrush}"
+                         Margin="0,4,0,0" />
+            </StackPanel>
+          </Grid>
+        </Border>
+
+        <Border x:Name="MigrationInfoBorder"
+                Background="{DynamicResource SystemFillColorSuccessBackgroundBrush}"
+                CornerRadius="{DynamicResource DesignCornerRadiusMd}"
+                Padding="12,10"
+                IsVisible="False">
+          <StackPanel Orientation="Horizontal" Spacing="6">
+            <ui:SymbolIcon Symbol="Message"
+                           FontSize="16"
+                           Foreground="{DynamicResource SystemFillColorSuccessBrush}" />
+            <TextBlock x:Name="MigrationInfoText"
+                       FontSize="12"
+                       TextWrapping="Wrap"
+                       Foreground="{DynamicResource SystemFillColorSuccessBrush}" />
+          </StackPanel>
+        </Border>
+      </StackPanel>
+
+      <StackPanel Grid.Row="2"
+                  Orientation="Horizontal"
+                  HorizontalAlignment="Right"
+                  Spacing="10"
+                  Margin="0,20,0,0">
+        <Button x:Name="CancelButton"
+                Content="取消"
+                Theme="{DynamicResource ButtonTheme}"
+                IsVisible="False" />
+        <Button x:Name="ConfirmButton"
+                Content="确认"
+                Theme="{DynamicResource AccentButtonTheme}" />
+      </StackPanel>
+    </Grid>
+  </Grid>
+</Window>

LanMountainDesktop.Launcher/Views/DataLocationPromptWindow.axaml.cs

@@ -0,0 +1,307 @@
+using Avalonia;
+using Avalonia.Animation;
+using Avalonia.Animation.Easings;
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Markup.Xaml;
+using Avalonia.Media;
+using Avalonia.Styling;
+using LanMountainDesktop.Launcher.Models;
+using LanMountainDesktop.Launcher.Services;
+
+namespace LanMountainDesktop.Launcher.Views;
+
+internal partial class DataLocationPromptWindow : Window
+{
+    private readonly TaskCompletionSource<DataLocationPromptResult?> _completionSource = new();
+    private readonly DataLocationResolver _resolver;
+    private bool _isTransitioning;
+
+    public DataLocationPromptWindow()
+    {
+        AvaloniaXamlLoader.Load(this);
+        Loaded += OnWindowLoaded;
+        Opened += OnWindowOpened;
+        _resolver = new DataLocationResolver(AppContext.BaseDirectory);
+    }
+
+    internal DataLocationPromptWindow(DataLocationResolver resolver)
+    {
+        AvaloniaXamlLoader.Load(this);
+        Loaded += OnWindowLoaded;
+        Opened += OnWindowOpened;
+        _resolver = resolver;
+    }
+
+    private void OnWindowLoaded(object? sender, RoutedEventArgs e)
+    {
+        BindControls();
+        UpdateUiState();
+    }
+
+    private void BindControls()
+    {
+        var systemRadio = this.FindControl<RadioButton>("SystemRadio");
+        var portableRadio = this.FindControl<RadioButton>("PortableRadio");
+        var confirmButton = this.FindControl<Button>("ConfirmButton");
+        var cancelButton = this.FindControl<Button>("CancelButton");
+
+        if (systemRadio is not null)
+        {
+            systemRadio.Checked += OnSelectionChanged;
+            systemRadio.Unchecked += OnSelectionChanged;
+        }
+
+        if (portableRadio is not null)
+        {
+            portableRadio.Checked += OnSelectionChanged;
+            portableRadio.Unchecked += OnSelectionChanged;
+        }
+
+        if (confirmButton is not null)
+        {
+            confirmButton.Click += OnConfirmClick;
+        }
+
+        if (cancelButton is not null)
+        {
+            cancelButton.Click += OnCancelClick;
+        }
+    }
+
+    private void UpdateUiState()
+    {
+        var systemPathText = this.FindControl<TextBlock>("SystemPathText");
+        var portablePathText = this.FindControl<TextBlock>("PortablePathText");
+        var adminWarningBanner = this.FindControl<Border>("AdminWarningBanner");
+        var portableRadio = this.FindControl<RadioButton>("PortableRadio");
+        var migrationInfoBorder = this.FindControl<Border>("MigrationInfoBorder");
+        var migrationInfoText = this.FindControl<TextBlock>("MigrationInfoText");
+
+        if (systemPathText is not null)
+        {
+            systemPathText.Text = _resolver.DefaultSystemDataPath;
+        }
+
+        if (portablePathText is not null)
+        {
+            portablePathText.Text = _resolver.DefaultPortableDataPath;
+        }
+
+        var portableAllowed = _resolver.IsPortableModeAllowed();
+
+        if (adminWarningBanner is not null)
+        {
+            adminWarningBanner.IsVisible = !portableAllowed;
+        }
+
+        if (portableRadio is not null)
+        {
+            portableRadio.IsEnabled = portableAllowed;
+        }
+
+        var hasExistingData = _resolver.HasExistingSystemData();
+        if (migrationInfoBorder is not null)
+        {
+            migrationInfoBorder.IsVisible = hasExistingData;
+        }
+
+        if (migrationInfoText is not null && hasExistingData)
+        {
+            migrationInfoText.Text = "检测到系统用户目录已有应用数据。如果选择保存在应用安装目录，将自动迁移现有数据。";
+        }
+    }
+
+    private void OnSelectionChanged(object? sender, RoutedEventArgs e)
+    {
+        var systemRadio = this.FindControl<RadioButton>("SystemRadio");
+        var portableRadio = this.FindControl<RadioButton>("PortableRadio");
+        var systemBorder = this.FindControl<Border>("SystemOptionBorder");
+        var portableBorder = this.FindControl<Border>("PortableOptionBorder");
+
+        var isSystem = systemRadio?.IsChecked == true;
+        var isPortable = portableRadio?.IsChecked == true;
+
+        if (systemBorder is not null)
+        {
+            systemBorder.BorderBrush = isSystem
+                ? Application.Current?.FindResource("AccentFillColorDefaultBrush") as IBrush
+                : Application.Current?.FindResource("CardStrokeColorDefaultBrush") as IBrush;
+            systemBorder.BorderThickness = isSystem ? new Thickness(2) : new Thickness(1);
+        }
+
+        if (portableBorder is not null)
+        {
+            portableBorder.BorderBrush = isPortable
+                ? Application.Current?.FindResource("AccentFillColorDefaultBrush") as IBrush
+                : Application.Current?.FindResource("CardStrokeColorDefaultBrush") as IBrush;
+            portableBorder.BorderThickness = isPortable ? new Thickness(2) : new Thickness(1);
+        }
+    }
+
+    private async void OnConfirmClick(object? sender, RoutedEventArgs e)
+    {
+        if (_isTransitioning)
+        {
+            return;
+        }
+
+        _isTransitioning = true;
+
+        var portableRadio = this.FindControl<RadioButton>("PortableRadio");
+        var selectedMode = portableRadio?.IsChecked == true
+            ? DataLocationMode.Portable
+            : DataLocationMode.System;
+
+        var migrateExistingData = selectedMode == DataLocationMode.Portable && _resolver.HasExistingSystemData();
+
+        try
+        {
+            await PlayExitAnimationAsync();
+            _completionSource.TrySetResult(new DataLocationPromptResult
+            {
+                SelectedMode = selectedMode,
+                MigrateExistingData = migrateExistingData
+            });
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Error during data location prompt exit animation: {ex.Message}");
+            _completionSource.TrySetResult(new DataLocationPromptResult
+            {
+                SelectedMode = selectedMode,
+                MigrateExistingData = migrateExistingData
+            });
+        }
+    }
+
+    private async void OnCancelClick(object? sender, RoutedEventArgs e)
+    {
+        if (_isTransitioning)
+        {
+            return;
+        }
+
+        _isTransitioning = true;
+
+        try
+        {
+            await PlayExitAnimationAsync();
+            _completionSource.TrySetResult(null);
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Error during data location prompt cancel: {ex.Message}");
+            _completionSource.TrySetResult(null);
+        }
+    }
+
+    private async void OnWindowOpened(object? sender, EventArgs e)
+    {
+        await PlayEntranceAnimationAsync();
+    }
+
+    private async Task PlayEntranceAnimationAsync()
+    {
+        try
+        {
+            var contentGrid = this.FindControl<Grid>("ContentGrid");
+            if (contentGrid is null)
+            {
+                return;
+            }
+
+            var translateTransform = contentGrid.RenderTransform as TranslateTransform ?? new TranslateTransform();
+            contentGrid.RenderTransform = translateTransform;
+
+            contentGrid.Opacity = 0;
+            translateTransform.Y = 24;
+
+            var fadeInAnimation = new Animation
+            {
+                Duration = TimeSpan.FromMilliseconds(500),
+                Easing = new CubicEaseOut(),
+                Children =
+                {
+                    new KeyFrame
+                    {
+                        Setters = { new Setter(OpacityProperty, 0.0) },
+                        KeyTime = TimeSpan.FromMilliseconds(0)
+                    },
+                    new KeyFrame
+                    {
+                        Setters = { new Setter(OpacityProperty, 1.0) },
+                        KeyTime = TimeSpan.FromMilliseconds(500)
+                    }
+                }
+            };
+
+            var slideUpAnimation = new Animation
+            {
+                Duration = TimeSpan.FromMilliseconds(500),
+                Easing = new CubicEaseOut(),
+                Children =
+                {
+                    new KeyFrame
+                    {
+                        Setters = { new Setter(TranslateTransform.YProperty, 24.0) },
+                        KeyTime = TimeSpan.FromMilliseconds(0)
+                    },
+                    new KeyFrame
+                    {
+                        Setters = { new Setter(TranslateTransform.YProperty, 0.0) },
+                        KeyTime = TimeSpan.FromMilliseconds(500)
+                    }
+                }
+            };
+
+            await Task.WhenAll(
+                fadeInAnimation.RunAsync(contentGrid),
+                slideUpAnimation.RunAsync(translateTransform));
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Error playing data location prompt entrance animation: {ex.Message}");
+        }
+    }
+
+    private async Task PlayExitAnimationAsync()
+    {
+        try
+        {
+            var contentGrid = this.FindControl<Grid>("ContentGrid");
+            if (contentGrid is null)
+            {
+                await Task.Delay(150);
+                return;
+            }
+
+            var fadeOutAnimation = new Animation
+            {
+                Duration = TimeSpan.FromMilliseconds(200),
+                Easing = new CubicEaseIn(),
+                Children =
+                {
+                    new KeyFrame
+                    {
+                        Setters = { new Setter(OpacityProperty, 1.0) },
+                        KeyTime = TimeSpan.FromMilliseconds(0)
+                    },
+                    new KeyFrame
+                    {
+                        Setters = { new Setter(OpacityProperty, 0.0) },
+                        KeyTime = TimeSpan.FromMilliseconds(200)
+                    }
+                }
+            };
+
+            await fadeOutAnimation.RunAsync(contentGrid);
+        }
+        catch (Exception ex)
+        {
+            Logger.Warn($"Error playing data location prompt exit animation: {ex.Message}");
+        }
+    }
+
+    internal Task<DataLocationPromptResult?> WaitForChoiceAsync() => _completionSource.Task;
+}

LanMountainDesktop/Program.cs

@@ -22,6 +22,7 @@ public sealed class Program
     public static void Main(string[] args)
     {
         AppLogger.Initialize();
+        AppDataPathProvider.Initialize(args);
         DevPluginOptions.Parse(args);
         RegisterGlobalExceptionLogging();
         var restartParentProcessId = LauncherRuntimeMetadata.GetRestartParentProcessId(args);

LanMountainDesktop/Services/AppDataPathProvider.cs

@@ -0,0 +1,66 @@
+namespace LanMountainDesktop.Services;
+
+public static class AppDataPathProvider
+{
+    private static string? _overriddenDataRoot;
+
+    public static void Initialize(string[] args)
+    {
+        var dataRoot = ResolveDataRootFromArgs(args);
+        if (!string.IsNullOrWhiteSpace(dataRoot))
+        {
+            _overriddenDataRoot = Path.GetFullPath(dataRoot);
+            AppLogger.Info("AppDataPath", $"Data root overridden by launcher: '{_overriddenDataRoot}'.");
+        }
+        else
+        {
+            var envDataRoot = Environment.GetEnvironmentVariable("LMD_DATA_ROOT");
+            if (!string.IsNullOrWhiteSpace(envDataRoot))
+            {
+                _overriddenDataRoot = Path.GetFullPath(envDataRoot);
+                AppLogger.Info("AppDataPath", $"Data root overridden by environment variable: '{_overriddenDataRoot}'.");
+            }
+        }
+    }
+
+    public static string GetDataRoot()
+    {
+        if (!string.IsNullOrWhiteSpace(_overriddenDataRoot))
+        {
+            return _overriddenDataRoot;
+        }
+
+        return Path.Combine(
+            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+            "LanMountainDesktop");
+    }
+
+    public static string GetSettingsDirectory()
+    {
+        return GetDataRoot();
+    }
+
+    public static string GetPluginMarketDirectory()
+    {
+        return Path.Combine(GetDataRoot(), "PluginMarket");
+    }
+
+    public static string GetWallpapersDirectory()
+    {
+        return Path.Combine(GetDataRoot(), "Wallpapers");
+    }
+
+    private static string? ResolveDataRootFromArgs(string[] args)
+    {
+        const string prefix = "--data-root=";
+        foreach (var arg in args)
+        {
+            if (arg.StartsWith(prefix, StringComparison.OrdinalIgnoreCase))
+            {
+                return arg[prefix.Length..];
+            }
+        }
+
+        return null;
+    }
+}

LanMountainDesktop/Services/AppDatabaseService.cs

@@ -24,8 +24,7 @@ public sealed class AppDatabaseService
 
     public AppDatabaseService()
     {
-        var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
-        var dataDirectory = Path.Combine(appData, "LanMountainDesktop");
+        var dataDirectory = AppDataPathProvider.GetDataRoot();
         _databasePath = Path.Combine(dataDirectory, "app.db");
     }
 

LanMountainDesktop/Services/AppSettingsService.cs

@@ -27,8 +27,7 @@ public sealed class AppSettingsService
 
     public AppSettingsService()
     {
-        var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
-        var settingsDirectory = Path.Combine(appData, "LanMountainDesktop");
+        var settingsDirectory = AppDataPathProvider.GetSettingsDirectory();
         _settingsPath = Path.Combine(settingsDirectory, "settings.json");
     }
 

LanMountainDesktop/Services/LauncherSettingsService.cs

@@ -30,8 +30,7 @@ public sealed class LauncherSettingsService
 
     public LauncherSettingsService()
     {
-        var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
-        var settingsDirectory = Path.Combine(appData, "LanMountainDesktop");
+        var settingsDirectory = AppDataPathProvider.GetSettingsDirectory();
         _settingsPath = Path.Combine(settingsDirectory, "launcher-settings.json");
         _legacyAppSettingsPath = Path.Combine(settingsDirectory, "settings.json");
     }

LanMountainDesktop/Services/Settings/ComponentDomainStorage.cs

@@ -76,9 +76,7 @@ internal sealed class SqliteComponentDomainStorage :
     public SqliteComponentDomainStorage(string? settingsRoot = null)
     {
         _settingsRoot = string.IsNullOrWhiteSpace(settingsRoot)
-            ? Path.Combine(
-                Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
-                "LanMountainDesktop")
+            ? AppDataPathProvider.GetDataRoot()
             : settingsRoot.Trim();
         _dbPath = Path.Combine(_settingsRoot, "component-state.db");
         _layoutJsonPath = Path.Combine(_settingsRoot, "desktop-layout-settings.json");

LanMountainDesktop/Services/Settings/SettingsDomainServices.cs

@@ -167,10 +167,7 @@ internal sealed class WallpaperMediaService : IWallpaperMediaService
 
     public WallpaperMediaService()
     {
-        var appDataRoot = Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
-            "LanMountainDesktop");
-        _wallpapersDirectory = Path.Combine(appDataRoot, "Wallpapers");
+        _wallpapersDirectory = AppDataPathProvider.GetWallpapersDirectory();
     }
 
     public WallpaperMediaType DetectMediaType(string? path)
@@ -1026,10 +1023,7 @@ internal sealed class PluginCatalogSettingsService : IPluginCatalogSettingsServi
     {
         _pluginRuntimeService = pluginRuntimeService;
 
-        var dataRoot = Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
-            "LanMountainDesktop",
-            "PluginMarket");
+        var dataRoot = AppDataPathProvider.GetPluginMarketDirectory();
         var cacheService = new AirAppMarketCacheService(dataRoot);
         _indexService = new AirAppMarketIndexService(cacheService);
         if (_pluginRuntimeService is not null)
@@ -1049,10 +1043,7 @@ internal sealed class PluginCatalogSettingsService : IPluginCatalogSettingsServi
             return;
         }
 
-        var dataRoot = Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
-            "LanMountainDesktop",
-            "PluginMarket");
+        var dataRoot = AppDataPathProvider.GetPluginMarketDirectory();
         _installService = new AirAppMarketInstallService(_pluginRuntimeService, dataRoot);
     }
 

LanMountainDesktop/Services/Settings/SettingsService.cs

@@ -26,9 +26,7 @@ internal sealed class SettingsService : ISettingsService
 
     public SettingsService()
     {
-        var root = Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
-            "LanMountainDesktop");
+        var root = AppDataPathProvider.GetDataRoot();
         _pluginSettingsPath = Path.Combine(root, "plugin-settings.json");
     }