launcher: add avalonia packages, settings, locale, and progress hook

Adds Avalonia 11 + CommunityToolkit.Mvvm package references (no UI code
yet), a flat-key Loc resource loader with embedded cs.json/en.json, the
LauncherSettings JSON store with dev-mode-gated manifest URL override,
and an optional IProgress<long> bytesProgress hook on BlobDownloader so
the upcoming GUI can drive a progress bar from per-blob byte counts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Metin2Launcher/Config/LauncherSettings.cs

@@ -0,0 +1,93 @@
+using System.IO;
+using System.Text.Json;
+using Metin2Launcher.Logging;
+
+namespace Metin2Launcher.Config;
+
+/// <summary>
+/// User-editable settings persisted to .updates/launcher-settings.json.
+/// Only honored when DevMode == true for the URL override (defense in depth: a
+/// tampered local file alone cannot redirect updates).
+/// </summary>
+public sealed class LauncherSettings
+{
+    public string Locale { get; set; } = "cs";
+    public bool DevMode { get; set; } = false;
+    public string? ManifestUrlOverride { get; set; }
+
+    private static readonly JsonSerializerOptions _opts = new()
+    {
+        WriteIndented = true,
+    };
+
+    public static LauncherSettings Load(string path)
+    {
+        try
+        {
+            if (!File.Exists(path))
+                return new LauncherSettings();
+            var json = File.ReadAllText(path);
+            return JsonSerializer.Deserialize<LauncherSettings>(json) ?? new LauncherSettings();
+        }
+        catch (Exception ex)
+        {
+            Log.Warn("failed to read launcher settings, using defaults: " + ex.Message);
+            return new LauncherSettings();
+        }
+    }
+
+    public void Save(string path)
+    {
+        try
+        {
+            Directory.CreateDirectory(Path.GetDirectoryName(path)!);
+            var json = JsonSerializer.Serialize(this, _opts);
+            File.WriteAllText(path, json);
+        }
+        catch (Exception ex)
+        {
+            Log.Warn("failed to save launcher settings: " + ex.Message);
+        }
+    }
+
+    /// <summary>
+    /// Effective manifest URL respecting dev-mode gating.
+    /// </summary>
+    public string EffectiveManifestUrl()
+    {
+        if (DevMode && !string.IsNullOrWhiteSpace(ManifestUrlOverride))
+            return ManifestUrlOverride!;
+        return LauncherConfig.ManifestUrl;
+    }
+
+    /// <summary>
+    /// Derives signature URL from the (possibly overridden) manifest URL.
+    /// </summary>
+    public string EffectiveSignatureUrl()
+    {
+        var m = EffectiveManifestUrl();
+        if (m == LauncherConfig.ManifestUrl)
+            return LauncherConfig.SignatureUrl;
+        return m + ".sig";
+    }
+
+    /// <summary>
+    /// Derives the blob base URL from the (possibly overridden) manifest URL.
+    /// Same host, sibling /files path.
+    /// </summary>
+    public string EffectiveBlobBaseUrl()
+    {
+        var m = EffectiveManifestUrl();
+        if (m == LauncherConfig.ManifestUrl)
+            return LauncherConfig.BlobBaseUrl;
+        try
+        {
+            var u = new Uri(m);
+            return $"{u.Scheme}://{u.Authority}/files";
+        }
+        catch
+        {
+            return LauncherConfig.BlobBaseUrl;
+        }
+    }
+}

src/Metin2Launcher/Localization/Loc.cs

@@ -0,0 +1,70 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using System.Text.Json;
+
+namespace Metin2Launcher.Localization;
+
+/// <summary>
+/// Tiny flat key-value localization loader. Resources are embedded JSON dictionaries.
+/// Lookup falls back: requested locale -> en -> the key itself.
+/// </summary>
+public static class Loc
+{
+    private static readonly Dictionary<string, Dictionary<string, string>> _bundles = new();
+    private static string _current = "cs";
+
+    public static event Action? Changed;
+
+    public static string Current => _current;
+
+    public static IReadOnlyList<string> Available => new[] { "cs", "en" };
+
+    static Loc()
+    {
+        Load("cs");
+        Load("en");
+    }
+
+    private static void Load(string locale)
+    {
+        var asm = typeof(Loc).Assembly;
+        var resName = $"Metin2Launcher.Localization.{locale}.json";
+        using var s = asm.GetManifestResourceStream(resName);
+        if (s is null)
+        {
+            _bundles[locale] = new Dictionary<string, string>();
+            return;
+        }
+        using var sr = new StreamReader(s);
+        var json = sr.ReadToEnd();
+        var dict = JsonSerializer.Deserialize<Dictionary<string, string>>(json)
+                   ?? new Dictionary<string, string>();
+        _bundles[locale] = dict;
+    }
+
+    public static void SetLocale(string locale)
+    {
+        if (!_bundles.ContainsKey(locale))
+            locale = "en";
+        if (_current == locale) return;
+        _current = locale;
+        Changed?.Invoke();
+    }
+
+    public static string Get(string key)
+    {
+        if (_bundles.TryGetValue(_current, out var d) && d.TryGetValue(key, out var v))
+            return v;
+        if (_bundles.TryGetValue("en", out var en) && en.TryGetValue(key, out var ev))
+            return ev;
+        return key;
+    }
+
+    public static string Get(string key, params object?[] args)
+    {
+        var fmt = Get(key);
+        try { return string.Format(fmt, args); }
+        catch { return fmt; }
+    }
+}

src/Metin2Launcher/Localization/cs.json

@@ -0,0 +1,32 @@
+{
+  "window.title": "Metin2 Launcher",
+  "banner.title": "METIN2 LAUNCHER",
+  "banner.version": "v{0}",
+  "button.play": "Hrát",
+  "button.exit": "Konec",
+  "button.settings": "Nastavení",
+  "button.close": "Zavřít",
+  "button.ok": "OK",
+  "button.cancel": "Zrušit",
+  "status.idle": "Připraveno",
+  "status.fetchingManifest": "Kontrola aktualizací…",
+  "status.verifyingSignature": "Ověřování podpisu vydání…",
+  "status.diffing": "Porovnávání lokálních souborů…",
+  "status.downloading": "Stahování aktualizací…",
+  "status.applying": "Instalace aktualizací…",
+  "status.upToDate": "Klient je aktuální",
+  "status.offlineFallback": "Server aktualizací nedostupný, používá se lokální klient",
+  "status.signatureFailed": "Aktualizace odmítnuta: neplatný podpis manifestu",
+  "status.launching": "Spouštění Metin2…",
+  "detail.fileProgress": "{0} ({1} z {2})",
+  "news.title": "Novinky",
+  "news.empty": "Žádné novinky.",
+  "news.previousHeader": "Předchozí verze {0}",
+  "settings.title": "Nastavení",
+  "settings.language": "Jazyk",
+  "settings.language.cs": "Čeština",
+  "settings.language.en": "English",
+  "settings.manifestUrl": "URL manifestu serveru",
+  "settings.devMode": "Vývojářský režim: povolit přepsání",
+  "settings.note": "Přepsání URL je ignorováno bez vývojářského režimu."
+}

src/Metin2Launcher/Localization/en.json

@@ -0,0 +1,32 @@
+{
+  "window.title": "Metin2 Launcher",
+  "banner.title": "METIN2 LAUNCHER",
+  "banner.version": "v{0}",
+  "button.play": "Play",
+  "button.exit": "Exit",
+  "button.settings": "Settings",
+  "button.close": "Close",
+  "button.ok": "OK",
+  "button.cancel": "Cancel",
+  "status.idle": "Idle",
+  "status.fetchingManifest": "Checking for updates…",
+  "status.verifyingSignature": "Verifying release signature…",
+  "status.diffing": "Comparing local files…",
+  "status.downloading": "Downloading updates…",
+  "status.applying": "Installing updates…",
+  "status.upToDate": "Up to date",
+  "status.offlineFallback": "Update server unreachable, using local client",
+  "status.signatureFailed": "Update refused: manifest signature invalid",
+  "status.launching": "Starting Metin2…",
+  "detail.fileProgress": "{0} ({1} of {2})",
+  "news.title": "News",
+  "news.empty": "No news.",
+  "news.previousHeader": "Previous version {0}",
+  "settings.title": "Settings",
+  "settings.language": "Language",
+  "settings.language.cs": "Čeština",
+  "settings.language.en": "English",
+  "settings.manifestUrl": "Server manifest URL",
+  "settings.devMode": "Dev mode: allow override",
+  "settings.note": "Override is ignored unless dev mode is enabled."
+}

src/Metin2Launcher/Metin2Launcher.csproj

@@ -7,12 +7,23 @@
     <Nullable>enable</Nullable>
     <RootNamespace>Metin2Launcher</RootNamespace>
     <AssemblyName>Metin2Launcher</AssemblyName>
-    <InvariantGlobalization>true</InvariantGlobalization>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
+    <BuiltInComInteropSupport>true</BuiltInComInteropSupport>
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Avalonia" Version="11.2.2" />
+    <PackageReference Include="Avalonia.Desktop" Version="11.2.2" />
+    <PackageReference Include="Avalonia.Themes.Fluent" Version="11.2.2" />
+    <PackageReference Include="Avalonia.Fonts.Inter" Version="11.2.2" />
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.0" />
     <PackageReference Include="NSec.Cryptography" Version="24.4.0" />
     <PackageReference Include="Velopack" Version="0.0.1053" />
   </ItemGroup>
 
+  <ItemGroup>
+    <EmbeddedResource Include="Localization\cs.json" />
+    <EmbeddedResource Include="Localization\en.json" />
+  </ItemGroup>
+
 </Project>

src/Metin2Launcher/Transfer/BlobDownloader.cs

@@ -41,7 +41,8 @@ public sealed class BlobDownloader
         string sha256,
         long expectedSize,
         string destinationPath,
-        CancellationToken ct)
+        CancellationToken ct,
+        IProgress<long>? bytesProgress = null)
     {
         var url = BlobUrl(_baseUrl, sha256);
         Directory.CreateDirectory(Path.GetDirectoryName(destinationPath)!);
@@ -52,7 +53,7 @@ public sealed class BlobDownloader
             ct.ThrowIfCancellationRequested();
             try
             {
-                await DownloadOnceAsync(url, expectedSize, destinationPath, ct).ConfigureAwait(false);
+                await DownloadOnceAsync(url, expectedSize, destinationPath, ct, bytesProgress).ConfigureAwait(false);
                 var actual = FileHasher.HashFileOrNull(destinationPath);
                 if (actual == sha256)
                     return;
@@ -83,7 +84,7 @@ public sealed class BlobDownloader
             $"blob {sha256} failed after {_maxRetries} attempts", lastError);
     }
 
-    private async Task DownloadOnceAsync(string url, long expectedSize, string destinationPath, CancellationToken ct)
+    private async Task DownloadOnceAsync(string url, long expectedSize, string destinationPath, CancellationToken ct, IProgress<long>? bytesProgress)
     {
         long have = File.Exists(destinationPath) ? new FileInfo(destinationPath).Length : 0;
         if (have > expectedSize)
@@ -95,8 +96,11 @@ public sealed class BlobDownloader
         if (have == expectedSize)
         {
             // Full size already on disk — the caller's hash check decides validity.
+            bytesProgress?.Report(expectedSize);
             return;
         }
+        if (have > 0)
+            bytesProgress?.Report(have);
 
         using var req = new HttpRequestMessage(HttpMethod.Get, url);
         if (have > 0)
@@ -119,7 +123,23 @@ public sealed class BlobDownloader
         var mode = have > 0 ? FileMode.Append : FileMode.Create;
         await using var fs = new FileStream(destinationPath, mode, FileAccess.Write, FileShare.None, 1024 * 1024);
         await using var net = await resp.Content.ReadAsStreamAsync(ct).ConfigureAwait(false);
-        await net.CopyToAsync(fs, 1024 * 1024, ct).ConfigureAwait(false);
+
+        if (bytesProgress is null)
+        {
+            await net.CopyToAsync(fs, 1024 * 1024, ct).ConfigureAwait(false);
+        }
+        else
+        {
+            var buf = new byte[1024 * 1024];
+            long total = have;
+            int read;
+            while ((read = await net.ReadAsync(buf, ct).ConfigureAwait(false)) > 0)
+            {
+                await fs.WriteAsync(buf.AsMemory(0, read), ct).ConfigureAwait(false);
+                total += read;
+                bytesProgress.Report(total);
+            }
+        }
     }
 
     private static void TryDelete(string path)

src/Metin2Launcher/app.manifest

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <assemblyIdentity version="0.1.0.0" name="Metin2Launcher.app"/>
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+      <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true</dpiAware>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
+    </windowsSettings>
+  </application>
+</assembly>

tests/Metin2Launcher.Tests/LauncherSettingsTests.cs

@@ -0,0 +1,70 @@
+using Metin2Launcher.Config;
+using Xunit;
+
+namespace Metin2Launcher.Tests;
+
+public class LauncherSettingsTests : IDisposable
+{
+    private readonly string _tmp;
+
+    public LauncherSettingsTests()
+    {
+        _tmp = Path.Combine(Path.GetTempPath(), "metin-settings-" + Guid.NewGuid());
+        Directory.CreateDirectory(_tmp);
+    }
+
+    public void Dispose()
+    {
+        try { Directory.Delete(_tmp, recursive: true); } catch { }
+    }
+
+    [Fact]
+    public void Defaults_when_file_missing()
+    {
+        var path = Path.Combine(_tmp, "missing.json");
+        var s = LauncherSettings.Load(path);
+        Assert.Equal("cs", s.Locale);
+        Assert.False(s.DevMode);
+        Assert.Null(s.ManifestUrlOverride);
+    }
+
+    [Fact]
+    public void Save_then_load_round_trip()
+    {
+        var path = Path.Combine(_tmp, "s.json");
+        var s = new LauncherSettings { Locale = "en", DevMode = true, ManifestUrlOverride = "https://example.test/m.json" };
+        s.Save(path);
+
+        var loaded = LauncherSettings.Load(path);
+        Assert.Equal("en", loaded.Locale);
+        Assert.True(loaded.DevMode);
+        Assert.Equal("https://example.test/m.json", loaded.ManifestUrlOverride);
+    }
+
+    [Fact]
+    public void Override_ignored_when_devmode_off()
+    {
+        var s = new LauncherSettings { DevMode = false, ManifestUrlOverride = "https://evil.test/m.json" };
+        Assert.Equal(LauncherConfig.ManifestUrl, s.EffectiveManifestUrl());
+        Assert.Equal(LauncherConfig.SignatureUrl, s.EffectiveSignatureUrl());
+        Assert.Equal(LauncherConfig.BlobBaseUrl, s.EffectiveBlobBaseUrl());
+    }
+
+    [Fact]
+    public void Override_used_when_devmode_on()
+    {
+        var s = new LauncherSettings { DevMode = true, ManifestUrlOverride = "https://example.test/m.json" };
+        Assert.Equal("https://example.test/m.json", s.EffectiveManifestUrl());
+        Assert.Equal("https://example.test/m.json.sig", s.EffectiveSignatureUrl());
+        Assert.Equal("https://example.test/files", s.EffectiveBlobBaseUrl());
+    }
+
+    [Fact]
+    public void Corrupt_file_falls_back_to_defaults()
+    {
+        var path = Path.Combine(_tmp, "bad.json");
+        File.WriteAllText(path, "{not json");
+        var s = LauncherSettings.Load(path);
+        Assert.Equal("cs", s.Locale);
+    }
+}

tests/Metin2Launcher.Tests/LocTests.cs

@@ -0,0 +1,42 @@
+using Metin2Launcher.Localization;
+using Xunit;
+
+namespace Metin2Launcher.Tests;
+
+public class LocTests
+{
+    [Fact]
+    public void Returns_value_for_known_key_in_cs()
+    {
+        Loc.SetLocale("cs");
+        Assert.Equal("Hrát", Loc.Get("button.play"));
+    }
+
+    [Fact]
+    public void Returns_value_for_known_key_in_en()
+    {
+        Loc.SetLocale("en");
+        Assert.Equal("Play", Loc.Get("button.play"));
+    }
+
+    [Fact]
+    public void Falls_back_to_key_for_unknown()
+    {
+        Loc.SetLocale("en");
+        Assert.Equal("nope.does.not.exist", Loc.Get("nope.does.not.exist"));
+    }
+
+    [Fact]
+    public void Format_substitutes_args()
+    {
+        Loc.SetLocale("en");
+        Assert.Equal("Previous version 0.1.0", Loc.Get("news.previousHeader", "0.1.0"));
+    }
+
+    [Fact]
+    public void Unknown_locale_falls_back_to_en()
+    {
+        Loc.SetLocale("xx");
+        Assert.Equal("Play", Loc.Get("button.play"));
+    }
+}