feat(i18n): add language dropdown to settings and persist selection

src/ClaudeDo.Ui/ViewModels/Modals/Settings/GeneralSettingsTabViewModel.cs

@@ -1,10 +1,14 @@
 using ClaudeDo.Data.Models;
+using ClaudeDo.Localization;
 using CommunityToolkit.Mvvm.ComponentModel;
 
 namespace ClaudeDo.Ui.ViewModels.Modals.Settings;
 
 public sealed partial class GeneralSettingsTabViewModel : ViewModelBase
 {
+    private readonly ILocalizer? _localizer;
+    private readonly Action<string>? _persist;
+
     [ObservableProperty] private string _defaultClaudeInstructions = "";
     [ObservableProperty] private string _defaultModel = ModelRegistry.DefaultAlias;
     [ObservableProperty] private int _defaultMaxTurns = 100;
@@ -18,6 +22,27 @@ public sealed partial class GeneralSettingsTabViewModel : ViewModelBase
     public IReadOnlyList<string> Models { get; } = ModelRegistry.Aliases;
     public IReadOnlyList<string> PermissionModes { get; } = PermissionModeRegistry.Modes;
 
+    public GeneralSettingsTabViewModel() { }
+
+    public GeneralSettingsTabViewModel(ILocalizer localizer, Action<string> persist)
+    {
+        _localizer = localizer;
+        _persist = persist;
+        Languages = localizer.AvailableLanguages;
+        _selectedLanguage = Languages.FirstOrDefault(l => l.Code == localizer.CurrentCode);
+    }
+
+    public IReadOnlyList<LanguageOption> Languages { get; } = Array.Empty<LanguageOption>();
+
+    [ObservableProperty] private LanguageOption? _selectedLanguage;
+
+    partial void OnSelectedLanguageChanged(LanguageOption? value)
+    {
+        if (value is null || _localizer is null) return;
+        _localizer.SetLanguage(value.Value.Code);
+        _persist?.Invoke(value.Value.Code);
+    }
+
     public string? Validate()
     {
         if (DefaultMaxTurns < 1 || DefaultMaxTurns > 200)

src/ClaudeDo.Ui/ViewModels/Modals/SettingsModalViewModel.cs

@@ -1,5 +1,6 @@
 using System.Linq;
 using ClaudeDo.Data;
+using ClaudeDo.Localization;
 using ClaudeDo.Ui.Services;
 using ClaudeDo.Ui.ViewModels.Modals.Settings;
 using CommunityToolkit.Mvvm.ComponentModel;
@@ -22,10 +23,15 @@ public sealed partial class SettingsModalViewModel : ViewModelBase
 
     public Action? CloseAction { get; set; }
 
-    public SettingsModalViewModel(WorkerClient worker, PrimeClaudeTabViewModel prime)
+    public SettingsModalViewModel(WorkerClient worker, PrimeClaudeTabViewModel prime,
+                                  ILocalizer localizer, AppSettings appSettings)
     {
         _worker = worker;
-        General = new GeneralSettingsTabViewModel();
+        General = new GeneralSettingsTabViewModel(localizer, code =>
+        {
+            appSettings.Language = code;
+            appSettings.Save();
+        });
         Worktrees = new WorktreesSettingsTabViewModel(worker);
         Files = new FilesSettingsTabViewModel(worker);
         Prime = prime;

src/ClaudeDo.Ui/Views/Modals/SettingsModalView.axaml

@@ -3,6 +3,8 @@
         xmlns:vm="using:ClaudeDo.Ui.ViewModels.Modals"
         xmlns:settings="using:ClaudeDo.Ui.ViewModels.Modals.Settings"
         xmlns:ctl="using:ClaudeDo.Ui.Views.Controls"
+        xmlns:loc="using:ClaudeDo.Ui.Localization"
+        xmlns:locm="using:ClaudeDo.Localization"
         x:Class="ClaudeDo.Ui.Views.Modals.SettingsModalView"
         x:DataType="vm:SettingsModalViewModel"
         Title="Settings"
@@ -45,6 +47,18 @@
         <TabItem Header="General">
           <ScrollViewer>
             <StackPanel Spacing="12" Margin="0,8,0,0">
+              <StackPanel Spacing="4">
+                <TextBlock Classes="field-label" Text="{loc:Tr settings.language}"/>
+                <ComboBox ItemsSource="{Binding General.Languages}"
+                          SelectedItem="{Binding General.SelectedLanguage, Mode=TwoWay}"
+                          HorizontalAlignment="Left" Width="220">
+                  <ComboBox.ItemTemplate>
+                    <DataTemplate x:DataType="locm:LanguageOption">
+                      <TextBlock Text="{Binding Name}"/>
+                    </DataTemplate>
+                  </ComboBox.ItemTemplate>
+                </ComboBox>
+              </StackPanel>
               <StackPanel Spacing="4">
                 <TextBlock Classes="field-label" Text="Default instructions"/>
                 <TextBox AcceptsReturn="True" TextWrapping="Wrap" Height="110"

tests/ClaudeDo.Ui.Tests/LanguageSettingTests.cs

@@ -0,0 +1,35 @@
+using ClaudeDo.Localization;
+using ClaudeDo.Ui;
+using ClaudeDo.Ui.ViewModels.Modals.Settings;
+
+namespace ClaudeDo.Ui.Tests;
+
+public class LanguageSettingTests
+{
+    private static Localizer Make()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "loc_" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        File.WriteAllText(Path.Combine(dir, "en.json"),
+            """{ "metadata": { "code": "en", "name": "English" }, "settings": { "save": "Save" } }""");
+        File.WriteAllText(Path.Combine(dir, "de.json"),
+            """{ "metadata": { "code": "de", "name": "Deutsch" }, "settings": { "save": "Speichern" } }""");
+        return new Localizer(LocaleStore.Load(dir), "en");
+    }
+
+    [Fact]
+    public void Selecting_language_switches_localizer_and_persists()
+    {
+        var loc = Make();
+        var settings = new AppSettings();
+        var saved = false;
+        var vm = new GeneralSettingsTabViewModel(loc, code => { settings.Language = code; saved = true; });
+
+        var de = vm.Languages.First(l => l.Code == "de");
+        vm.SelectedLanguage = de;
+
+        Assert.Equal("de", loc.CurrentCode);
+        Assert.True(saved);
+        Assert.Equal("de", settings.Language);
+    }
+}