refactor(app): compose settings and developer tools

src/AcDream.App/Settings/RuntimeKeyBindingTarget.cs

@@ -0,0 +1,45 @@
+using AcDream.UI.Abstractions.Input;
+
+namespace AcDream.App.Settings;
+
+internal interface IRuntimeKeyBindingTarget
+{
+    void Apply(KeyBindings bindings);
+}
+
+/// <summary>
+/// Applies a settings-panel keymap to the live dispatcher and then persists
+/// that exact map. Persistence failure is reported without rolling back the
+/// already accepted live binding, matching the former startup-root callback.
+/// </summary>
+internal sealed class RuntimeKeyBindingTarget : IRuntimeKeyBindingTarget
+{
+    private readonly InputDispatcher _dispatcher;
+    private readonly string _path;
+    private readonly Action<string> _log;
+
+    public RuntimeKeyBindingTarget(
+        InputDispatcher dispatcher,
+        string? path = null,
+        Action<string>? log = null)
+    {
+        _dispatcher = dispatcher ?? throw new ArgumentNullException(nameof(dispatcher));
+        _path = path ?? KeyBindings.DefaultPath();
+        _log = log ?? Console.WriteLine;
+    }
+
+    public void Apply(KeyBindings bindings)
+    {
+        ArgumentNullException.ThrowIfNull(bindings);
+        _dispatcher.SetBindings(bindings);
+        try
+        {
+            bindings.SaveToFile(_path);
+            _log($"keybinds: saved to {_path}");
+        }
+        catch (Exception failure)
+        {
+            _log($"keybinds: save failed: {failure.Message}");
+        }
+    }
+}

src/AcDream.App/Settings/RuntimeSettingsController.cs

@@ -79,6 +79,34 @@ internal sealed record RuntimeSettingsSnapshot(
     CharacterSettings Character,
     QualitySettings Quality);
 
+/// <summary>
+/// Expected-owner lease for the optional developer settings view model.
+/// Failed optional composition can withdraw only the instance it installed.
+/// </summary>
+internal sealed class RuntimeSettingsViewModelBinding : IDisposable
+{
+    private readonly RuntimeSettingsController _owner;
+    private bool _disposed;
+
+    public RuntimeSettingsViewModelBinding(
+        RuntimeSettingsController owner,
+        SettingsVM viewModel)
+    {
+        _owner = owner ?? throw new ArgumentNullException(nameof(owner));
+        ViewModel = viewModel ?? throw new ArgumentNullException(nameof(viewModel));
+    }
+
+    public SettingsVM ViewModel { get; }
+
+    public void Dispose()
+    {
+        if (_disposed)
+            return;
+        _owner.UnbindViewModel(ViewModel);
+        _disposed = true;
+    }
+}
+
 internal interface IRuntimeSettingsStartupTarget
 {
     void ApplyDisplay(DisplaySettings display);
@@ -248,6 +276,14 @@ internal sealed class RuntimeSettingsController :
         return _viewModel;
     }
 
+    public RuntimeSettingsViewModelBinding CreateViewModelBinding(
+        KeyBindings persistedBindings,
+        InputDispatcher dispatcher,
+        Action<KeyBindings> saveBindings) =>
+        new(
+            this,
+            CreateViewModel(persistedBindings, dispatcher, saveBindings));
+
     public void UnbindViewModel(SettingsVM? expected = null)
     {
         if (expected is null || ReferenceEquals(_viewModel, expected))