fix(launcher): harden updater crash recovery

tests/AcDream.Launcher.Tests/LauncherUpdateCompositionTests.cs

@@ -0,0 +1,65 @@
+using System.Text.Json;
+using AcDream.Launcher.Core.Orchestration;
+using AcDream.Launcher.Core.Profiles;
+using AcDream.Launcher.Core.Updates;
+using AcDream.Platform;
+
+namespace AcDream.Launcher.Tests;
+
+public sealed class LauncherUpdateCompositionTests : IDisposable
+{
+    private readonly string _root = Path.Combine(
+        Path.GetTempPath(),
+        "acdream-launcher-composition-tests",
+        Guid.NewGuid().ToString("N"));
+
+    public void Dispose()
+    {
+        if (Directory.Exists(_root))
+        {
+            Directory.Delete(_root, recursive: true);
+        }
+    }
+
+    [Theory]
+    [InlineData("io")]
+    [InlineData("permission")]
+    [InlineData("corrupt")]
+    public async Task StartupStorageFailureComposesUnavailableUpdaterWithoutThrowing(
+        string failure)
+    {
+        Directory.CreateDirectory(_root);
+        var paths = new ApplicationPathSet(
+            Path.Combine(_root, "config"),
+            Path.Combine(_root, "data"),
+            Path.Combine(_root, "cache"),
+            null);
+        Exception exception = failure switch
+        {
+            "io" => new IOException("storage offline"),
+            "permission" => new UnauthorizedAccessException("storage denied"),
+            "corrupt" => new JsonException("pointer corrupt"),
+            _ => throw new InvalidOperationException("Unknown fixture failure."),
+        };
+
+        using LauncherUpdateComposition composition = LauncherUpdateComposition.Create(
+            paths,
+            LauncherRuntimeIdentity.DetectRid(),
+            LauncherVersion.Parse("1.0.0"),
+            _root,
+            () => false,
+            (_, _) => throw exception);
+
+        Assert.Equal(ClientVersionState.Invalid, composition.Updater.CurrentClient.State);
+        Assert.Contains(
+            exception.Message,
+            composition.Updater.CurrentClient.Status,
+            StringComparison.Ordinal);
+        LauncherCapability capability = composition.Executables.GetAvailability(LaunchMode.Gui);
+        Assert.False(capability.IsAvailable);
+        Assert.Contains(exception.Message, capability.Reason, StringComparison.Ordinal);
+        LauncherUpdateException updateError = await Assert.ThrowsAsync<LauncherUpdateException>(
+            () => composition.Updater.CheckAsync());
+        Assert.Contains(exception.Message, updateError.Message, StringComparison.Ordinal);
+    }
+}