refactor(app): compose settings and developer tools

src/AcDream.App/Combat/LiveCombatAttackOperations.cs

@@ -33,8 +33,25 @@ internal interface ICombatFeedbackSink
 
 internal sealed class CombatFeedbackSlot : ICombatFeedbackSink
 {
-    public AcDream.UI.Abstractions.Panels.Debug.DebugVM? ViewModel { get; set; }
+    private AcDream.UI.Abstractions.Panels.Debug.DebugVM? _viewModel;
-    public void Show(string message) => ViewModel?.AddToast(message);
+
+    public void Bind(AcDream.UI.Abstractions.Panels.Debug.DebugVM viewModel)
+    {
+        ArgumentNullException.ThrowIfNull(viewModel);
+        if (_viewModel is not null && !ReferenceEquals(_viewModel, viewModel))
+            throw new InvalidOperationException(
+                "Combat feedback is already bound to a developer view model.");
+        _viewModel = viewModel;
+    }
+
+    public void Unbind(AcDream.UI.Abstractions.Panels.Debug.DebugVM viewModel)
+    {
+        ArgumentNullException.ThrowIfNull(viewModel);
+        if (ReferenceEquals(_viewModel, viewModel))
+            _viewModel = null;
+    }
+
+    public void Show(string message) => _viewModel?.AddToast(message);
 }
 
 internal sealed class CombatAttackOperationsSlot : ICombatAttackOperations

src/AcDream.App/Composition/SettingsDevToolsComposition.cs

@@ -0,0 +1,631 @@
+using AcDream.App.Combat;
+using AcDream.App.Diagnostics;
+using AcDream.App.Input;
+using AcDream.App.Rendering;
+using AcDream.App.Settings;
+using AcDream.Core.Chat;
+using AcDream.Core.Combat;
+using AcDream.Core.Player;
+using AcDream.UI.Abstractions.Input;
+using AcDream.UI.Abstractions.Panels.Chat;
+using AcDream.UI.Abstractions.Panels.Debug;
+using AcDream.UI.Abstractions.Panels.Settings;
+using AcDream.UI.Abstractions.Panels.Vitals;
+using AcDream.UI.ImGui;
+using Silk.NET.Input;
+using Silk.NET.OpenGL;
+using Silk.NET.Windowing;
+
+namespace AcDream.App.Composition;
+
+internal sealed record SettingsDevToolsResult(
+    AcDream.UI.Abstractions.Settings.QualitySettings ResolvedQuality,
+    DevToolsCompositionOwner? DevTools);
+
+internal sealed record SettingsDevToolsOptionalDependencies(
+    IDevToolsRuntimeFacts Facts,
+    IRuntimeKeyBindingTarget? KeyBindingTarget,
+    DeferredCanonicalWorldEntityCountSource WorldEntities,
+    DeferredRenderFrameDiagnosticsSource FrameDiagnostics,
+    DeferredDevToolsPlayerModeCommands PlayerModeCommands);
+
+internal sealed record SettingsDevToolsDependencies(
+    IView Window,
+    RuntimeSettingsController Settings,
+    IRuntimeSettingsStartupTarget StartupTarget,
+    HostQuiescenceGate HostQuiescence,
+    ChatLog Chat,
+    CombatState Combat,
+    LocalPlayerState LocalPlayer,
+    SettingsDevToolsOptionalDependencies? DevTools,
+    RuntimeDiagnosticCommandSlot DiagnosticCommands,
+    CombatFeedbackSlot CombatFeedback,
+    KeyBindings KeyBindings,
+    FrameProfiler FrameProfiler,
+    FramebufferResizeController FramebufferResize,
+    Action<string> Log);
+
+internal interface IGameWindowSettingsDevToolsPublication
+{
+    void PublishDevTools(DevToolsCompositionOwner value);
+}
+
+internal interface ISettingsDevToolsCompositionFactory
+{
+    bool IsSupported(IInputContext input);
+
+    IDevToolsInputContext CreateInputContext(
+        IInputContext input,
+        HostQuiescenceGate quiescence);
+
+    IImGuiBootstrapper CreateBootstrap(
+        GL gl,
+        IView window,
+        IInputContext input);
+
+    ImGuiPanelHost CreatePanelHost();
+
+    IDevToolsFrameBackend CreateBackend(
+        IImGuiBootstrapper bootstrap,
+        ImGuiPanelHost panels);
+}
+
+internal sealed class RetailSettingsDevToolsCompositionFactory
+    : ISettingsDevToolsCompositionFactory
+{
+    public bool IsSupported(IInputContext input) =>
+        input.Keyboards.Count > 0
+        && input.Mice.Count > 0
+        && input.Mice[0].ScrollWheels.Count > 0;
+
+    public IDevToolsInputContext CreateInputContext(
+        IInputContext input,
+        HostQuiescenceGate quiescence) =>
+        new QuiescentInputContext(input, quiescence);
+
+    public IImGuiBootstrapper CreateBootstrap(
+        GL gl,
+        IView window,
+        IInputContext input) =>
+        new ImGuiBootstrapper(gl, window, input);
+
+    public ImGuiPanelHost CreatePanelHost() => new();
+
+    public IDevToolsFrameBackend CreateBackend(
+        IImGuiBootstrapper bootstrap,
+        ImGuiPanelHost panels) =>
+        new ImGuiDevToolsFrameBackend(bootstrap, panels);
+}
+
+internal enum SettingsDevToolsCompositionPoint
+{
+    SettingsApplied,
+    InputContextCreated,
+    BootstrapCreated,
+    InputActivated,
+    PanelHostCreated,
+    VitalsRegistered,
+    ChatRegistered,
+    DebugViewModelCreated,
+    DiagnosticActionsBound,
+    CombatFeedbackBound,
+    DebugRegistered,
+    SettingsViewModelBound,
+    SettingsRegistered,
+    BackendCreated,
+    PresenterCreated,
+    FramebufferBound,
+    InitialLayoutApplied,
+    DevToolsPublished,
+}
+
+/// <summary>
+/// Complete optional developer frontend lifetime. Construction rollback and
+/// normal shutdown share the same named, retryable release operations.
+/// </summary>
+internal sealed class DevToolsCompositionOwner : IDisposable
+{
+    private readonly IDevToolsInputContext _input;
+    private readonly IDevToolsFrameBackend _backend;
+    private readonly ChatVM _chat;
+    private readonly DebugVM _debug;
+    private readonly RuntimeSettingsViewModelBinding? _settings;
+    private readonly CombatFeedbackSlot _combatFeedback;
+    private readonly FramebufferDevToolsBinding _framebuffer;
+    private readonly ResourceShutdownTransaction _frontendShutdown;
+    private bool _ownsInput;
+    private bool _ownsBackend;
+    private bool _ownsChat;
+    private bool _ownsDebug;
+    private bool _ownsSettings;
+    private bool _ownsCombatBinding;
+    private bool _ownsFramebuffer;
+
+    public DevToolsCompositionOwner(
+        IDevToolsInputContext input,
+        IDevToolsFrameBackend backend,
+        DevToolsFramePresenter presenter,
+        DevToolsCommandBusSource commandBus,
+        VitalsVM vitals,
+        ChatVM chat,
+        DebugVM debug,
+        SettingsDevToolsOptionalDependencies lateBindings,
+        RuntimeSettingsViewModelBinding? settings,
+        CombatFeedbackSlot combatFeedback,
+        FramebufferDevToolsBinding framebuffer)
+    {
+        _input = input ?? throw new ArgumentNullException(nameof(input));
+        _backend = backend ?? throw new ArgumentNullException(nameof(backend));
+        Presenter = presenter ?? throw new ArgumentNullException(nameof(presenter));
+        CommandBus = commandBus ?? throw new ArgumentNullException(nameof(commandBus));
+        Vitals = vitals ?? throw new ArgumentNullException(nameof(vitals));
+        _chat = chat ?? throw new ArgumentNullException(nameof(chat));
+        _debug = debug ?? throw new ArgumentNullException(nameof(debug));
+        LateBindings = lateBindings
+            ?? throw new ArgumentNullException(nameof(lateBindings));
+        _settings = settings;
+        _combatFeedback = combatFeedback ?? throw new ArgumentNullException(nameof(combatFeedback));
+        _framebuffer = framebuffer ?? throw new ArgumentNullException(nameof(framebuffer));
+
+        _frontendShutdown = new ResourceShutdownTransaction(
+            new ResourceShutdownStage("developer framebuffer binding",
+            [
+                new("framebuffer resize binding", ReleaseFramebuffer),
+            ]),
+            new ResourceShutdownStage("developer backend",
+            [
+                new("ImGui backend", ReleaseBackend),
+            ]),
+            new ResourceShutdownStage("developer view models",
+            [
+                new("settings view model binding", ReleaseSettings),
+                new("combat feedback binding", ReleaseCombatBinding),
+                new("debug combat subscriptions", ReleaseDebug),
+                new("chat transcript subscription", ReleaseChat),
+            ]));
+    }
+
+    public DevToolsFramePresenter Presenter { get; }
+    public DevToolsCommandBusSource CommandBus { get; }
+    public VitalsVM Vitals { get; }
+    public DebugVM Debug => _debug;
+    public SettingsDevToolsOptionalDependencies LateBindings { get; }
+
+    public bool IsDisposalComplete =>
+        _frontendShutdown.IsComplete && !_ownsInput;
+
+    public void AdoptInput() => _ownsInput = true;
+    public void AdoptBackend() => _ownsBackend = true;
+    public void AdoptChat() => _ownsChat = true;
+    public void AdoptDebug() => _ownsDebug = true;
+    public void AdoptSettings() => _ownsSettings = _settings is not null;
+    public void AdoptCombatBinding() => _ownsCombatBinding = true;
+    public void AdoptFramebuffer() => _ownsFramebuffer = true;
+
+    public void CompleteOwnership()
+    {
+        if (!_ownsInput
+            || !_ownsBackend
+            || !_ownsChat
+            || !_ownsDebug
+            || !_ownsCombatBinding
+            || !_ownsFramebuffer
+            || (_settings is not null && !_ownsSettings))
+        {
+            throw new InvalidOperationException(
+                "Developer composition ownership is incomplete.");
+        }
+    }
+
+    public void DeactivateInput()
+    {
+        CommandBus.Deactivate();
+        LateBindings.PlayerModeCommands.Deactivate();
+        LateBindings.FrameDiagnostics.Deactivate();
+        LateBindings.WorldEntities.Deactivate();
+        if (_ownsInput)
+            _input.Deactivate();
+    }
+
+    public void DetachInput()
+    {
+        if (!_ownsInput)
+            return;
+        _input.Dispose();
+        if (!_input.IsDisposalComplete)
+            throw new InvalidOperationException(
+                "Developer input callback cleanup remains incomplete.");
+        _ownsInput = false;
+    }
+
+    public void DisposeFrontend() => _frontendShutdown.CompleteOrThrow();
+
+    public void Dispose()
+    {
+        DeactivateInput();
+        DisposeFrontend();
+        DetachInput();
+    }
+
+    private void ReleaseFramebuffer()
+    {
+        if (!_ownsFramebuffer)
+            return;
+        _framebuffer.Dispose();
+        _ownsFramebuffer = false;
+    }
+
+    private void ReleaseCombatBinding()
+    {
+        if (!_ownsCombatBinding)
+            return;
+        _combatFeedback.Unbind(_debug);
+        _ownsCombatBinding = false;
+    }
+
+    private void ReleaseSettings()
+    {
+        if (!_ownsSettings)
+            return;
+        _settings!.Dispose();
+        _ownsSettings = false;
+    }
+
+    private void ReleaseDebug()
+    {
+        if (!_ownsDebug)
+            return;
+        _debug.Dispose();
+        _ownsDebug = false;
+    }
+
+    private void ReleaseChat()
+    {
+        if (!_ownsChat)
+            return;
+        _chat.Dispose();
+        _ownsChat = false;
+    }
+
+    private void ReleaseBackend()
+    {
+        if (!_ownsBackend)
+            return;
+        _backend.Dispose();
+        _ownsBackend = false;
+    }
+}
+
+internal sealed class CombatFeedbackBinding : IDisposable
+{
+    private readonly CombatFeedbackSlot _owner;
+    private readonly DebugVM _viewModel;
+    private bool _disposed;
+
+    public CombatFeedbackBinding(CombatFeedbackSlot owner, DebugVM viewModel)
+    {
+        _owner = owner ?? throw new ArgumentNullException(nameof(owner));
+        _viewModel = viewModel ?? throw new ArgumentNullException(nameof(viewModel));
+        _owner.Bind(_viewModel);
+    }
+
+    public void Dispose()
+    {
+        if (_disposed)
+            return;
+        _owner.Unbind(_viewModel);
+        _disposed = true;
+    }
+}
+
+/// <summary>
+/// Production Phase 3. Settings are required; the optional developer frontend
+/// may be abandoned only after every locally acquired edge has been removed.
+/// </summary>
+internal sealed class SettingsDevToolsCompositionPhase :
+    ISettingsDevToolsCompositionPhase<
+        GameWindowPlatformResult<GL, IInputContext>,
+        HostInputCameraResult,
+        ContentEffectsAudioResult,
+        SettingsDevToolsResult>
+{
+    private readonly SettingsDevToolsDependencies _dependencies;
+    private readonly IGameWindowSettingsDevToolsPublication _publication;
+    private readonly ISettingsDevToolsCompositionFactory _factory;
+    private readonly Action<SettingsDevToolsCompositionPoint>? _faultInjection;
+
+    public SettingsDevToolsCompositionPhase(
+        SettingsDevToolsDependencies dependencies,
+        IGameWindowSettingsDevToolsPublication publication,
+        ISettingsDevToolsCompositionFactory? factory = null,
+        Action<SettingsDevToolsCompositionPoint>? faultInjection = null)
+    {
+        _dependencies = dependencies ?? throw new ArgumentNullException(nameof(dependencies));
+        _publication = publication ?? throw new ArgumentNullException(nameof(publication));
+        _factory = factory ?? new RetailSettingsDevToolsCompositionFactory();
+        _faultInjection = faultInjection;
+    }
+
+    public SettingsDevToolsResult Compose(
+        GameWindowPlatformResult<GL, IInputContext> platform,
+        HostInputCameraResult host,
+        ContentEffectsAudioResult content)
+    {
+        ArgumentNullException.ThrowIfNull(platform);
+        ArgumentNullException.ThrowIfNull(host);
+        ArgumentNullException.ThrowIfNull(content);
+
+        _dependencies.Settings.ApplyStartup(_dependencies.StartupTarget);
+        Fault(SettingsDevToolsCompositionPoint.SettingsApplied);
+
+        DevToolsCompositionOwner? devTools = _dependencies.DevTools is { } optional
+            ? ComposeOptionalDevTools(platform, host, optional)
+            : null;
+        return new SettingsDevToolsResult(
+            _dependencies.Settings.ResolvedQuality,
+            devTools);
+    }
+
+    private DevToolsCompositionOwner? ComposeOptionalDevTools(
+        GameWindowPlatformResult<GL, IInputContext> platform,
+        HostInputCameraResult host,
+        SettingsDevToolsOptionalDependencies optional)
+    {
+        var scope = new CompositionAcquisitionScope();
+        bool published = false;
+        try
+        {
+            if (!_factory.IsSupported(platform.Input))
+            {
+                _dependencies.Log(
+                    "devtools: keyboard, mouse, or scroll input unavailable — devtools disabled");
+                return null;
+            }
+
+            var inputLease = scope.Acquire(
+                "developer input context",
+                () => _factory.CreateInputContext(
+                    platform.Input,
+                    _dependencies.HostQuiescence),
+                static value => value.Dispose());
+            IDevToolsInputContext input = inputLease.Resource;
+            Fault(SettingsDevToolsCompositionPoint.InputContextCreated);
+
+            var bootstrapLease = scope.Acquire(
+                "ImGui bootstrap",
+                () => _factory.CreateBootstrap(
+                    platform.Graphics,
+                    _dependencies.Window,
+                    input),
+                static value => value.Dispose());
+            IImGuiBootstrapper bootstrap = bootstrapLease.Resource;
+            Fault(SettingsDevToolsCompositionPoint.BootstrapCreated);
+
+            input.Activate();
+            Fault(SettingsDevToolsCompositionPoint.InputActivated);
+
+            ImGuiPanelHost panelHost = _factory.CreatePanelHost();
+            Fault(SettingsDevToolsCompositionPoint.PanelHostCreated);
+
+            var vitals = new VitalsVM(
+                _dependencies.Combat,
+                _dependencies.LocalPlayer);
+            var vitalsPanel = new VitalsPanel(vitals);
+            panelHost.Register(vitalsPanel);
+            Fault(SettingsDevToolsCompositionPoint.VitalsRegistered);
+
+            var chatLease = scope.Acquire(
+                "developer chat view model",
+                () => new ChatVM(_dependencies.Chat)
+                {
+                    FpsProvider = () => optional.Facts.Fps,
+                    PositionProvider = () => optional.Facts.PlayerPosition,
+                },
+                static value => value.Dispose());
+            ChatVM chatVm = chatLease.Resource;
+            var chatPanel = new ChatPanel(chatVm);
+            panelHost.Register(chatPanel);
+            Fault(SettingsDevToolsCompositionPoint.ChatRegistered);
+
+            var debugLease = scope.Acquire(
+                "developer debug view model",
+                () => CreateDebugViewModel(optional.Facts),
+                static value => value.Dispose());
+            DebugVM debugVm = debugLease.Resource;
+            Fault(SettingsDevToolsCompositionPoint.DebugViewModelCreated);
+            debugVm.CycleTimeOfDay = _dependencies.DiagnosticCommands.CycleTimeOfDay;
+            debugVm.CycleWeather = _dependencies.DiagnosticCommands.CycleWeather;
+            debugVm.ToggleCollisionWires =
+                _dependencies.DiagnosticCommands.ToggleCollisionWireframes;
+            debugVm.ToggleFlyMode = optional.PlayerModeCommands.ToggleFlyOrChase;
+            Fault(SettingsDevToolsCompositionPoint.DiagnosticActionsBound);
+
+            var combatBindingLease = scope.Acquire(
+                "combat feedback binding",
+                () => new CombatFeedbackBinding(
+                    _dependencies.CombatFeedback,
+                    debugVm),
+                static value => value.Dispose());
+            Fault(SettingsDevToolsCompositionPoint.CombatFeedbackBound);
+
+            var debugPanel = new DebugPanel(debugVm);
+            panelHost.Register(debugPanel);
+            Fault(SettingsDevToolsCompositionPoint.DebugRegistered);
+
+            RuntimeSettingsViewModelBinding? settingsBinding = null;
+            SettingsPanel? settingsPanel = null;
+            CompositionAcquisitionScope.CompositionAcquisitionLease<RuntimeSettingsViewModelBinding>?
+                settingsLease = null;
+            if (host.InputDispatcher is not null
+                && optional.KeyBindingTarget is not null)
+            {
+                settingsLease = scope.Acquire(
+                    "settings view model binding",
+                    () => _dependencies.Settings.CreateViewModelBinding(
+                        _dependencies.KeyBindings,
+                        host.InputDispatcher,
+                        optional.KeyBindingTarget.Apply),
+                    static value => value.Dispose());
+                settingsBinding = settingsLease.Resource;
+                Fault(SettingsDevToolsCompositionPoint.SettingsViewModelBound);
+                settingsPanel = new SettingsPanel(settingsBinding.ViewModel);
+                panelHost.Register(settingsPanel);
+                Fault(SettingsDevToolsCompositionPoint.SettingsRegistered);
+            }
+
+            var backendLease = scope.Acquire(
+                "developer frame backend",
+                () => _factory.CreateBackend(bootstrap, panelHost),
+                static value => value.Dispose());
+            IDevToolsFrameBackend backend = backendLease.Resource;
+            bootstrapLease.Transfer();
+            Fault(SettingsDevToolsCompositionPoint.BackendCreated);
+
+            var cameraMenu = new DevToolsCameraMenuOperations(
+                host.CameraController,
+                optional.PlayerModeCommands);
+            var commandBus = new DevToolsCommandBusSource();
+            var presenter = new DevToolsFramePresenter(
+                backend,
+                cameraMenu,
+                commandBus,
+                _dependencies.FrameProfiler,
+                new DevToolsPanelSet(
+                    vitalsPanel,
+                    chatPanel,
+                    debugPanel,
+                    debugVm,
+                    settingsPanel));
+            Fault(SettingsDevToolsCompositionPoint.PresenterCreated);
+
+            var framebufferLease = scope.Acquire(
+                "developer framebuffer binding",
+                () => new FramebufferDevToolsBinding(
+                    _dependencies.FramebufferResize,
+                    new DevToolsFramebufferTarget(presenter)),
+                static value => value.Dispose());
+            Fault(SettingsDevToolsCompositionPoint.FramebufferBound);
+
+            presenter.ResetLayout(
+                _dependencies.Window.Size.X,
+                _dependencies.Window.Size.Y,
+                DevToolsPanelLayoutCondition.FirstUseEver);
+            Fault(SettingsDevToolsCompositionPoint.InitialLayoutApplied);
+
+            var ownerLease = scope.Acquire(
+                "developer composition owner",
+                () => new DevToolsCompositionOwner(
+                    input,
+                    backend,
+                    presenter,
+                    commandBus,
+                    vitals,
+                    chatVm,
+                    debugVm,
+                    optional,
+                    settingsBinding,
+                    _dependencies.CombatFeedback,
+                    framebufferLease.Resource),
+                static value => value.Dispose());
+            DevToolsCompositionOwner owner = ownerLease.Resource;
+
+            inputLease.Transfer();
+            owner.AdoptInput();
+            backendLease.Transfer();
+            owner.AdoptBackend();
+            chatLease.Transfer();
+            owner.AdoptChat();
+            debugLease.Transfer();
+            owner.AdoptDebug();
+            combatBindingLease.Transfer();
+            owner.AdoptCombatBinding();
+            if (settingsLease is not null)
+            {
+                settingsLease.Transfer();
+                owner.AdoptSettings();
+            }
+            framebufferLease.Transfer();
+            owner.AdoptFramebuffer();
+            owner.CompleteOwnership();
+
+            owner = ownerLease.Publish(
+                _publication.PublishDevTools);
+            published = true;
+            Fault(SettingsDevToolsCompositionPoint.DevToolsPublished);
+            scope.Complete();
+            _dependencies.Log(
+                "devtools: ImGui panel host ready " +
+                "(VitalsPanel + ChatPanel + DebugPanel + SettingsPanel registered)");
+            return owner;
+        }
+        catch (Exception failure)
+        {
+            if (published)
+                throw;
+            try
+            {
+                scope.RollbackAndThrow(failure);
+            }
+            catch (Exception rolledBack) when (!HasIncompleteCleanup(rolledBack))
+            {
+                _dependencies.Log(
+                    $"devtools: ImGui init failed: {rolledBack.Message} — devtools disabled");
+                return null;
+            }
+
+            throw new System.Diagnostics.UnreachableException();
+        }
+    }
+
+    private DebugVM CreateDebugViewModel(IDevToolsRuntimeFacts facts)
+    {
+        ArgumentNullException.ThrowIfNull(facts);
+        return new DebugVM(
+            () => facts.PlayerPosition,
+            () => facts.PlayerHeadingDegrees,
+            () => facts.PlayerCellId,
+            () => facts.PlayerOnGround,
+            () => facts.InPlayerMode,
+            () => facts.InFlyMode,
+            () => facts.VerticalVelocity,
+            () => facts.EntityCount,
+            () => facts.AnimatedCount,
+            () => facts.VisibleLandblocks,
+            () => facts.TotalLandblocks,
+            () => facts.ShadowObjectCount,
+            () => facts.NearestObjectDistance,
+            () => facts.NearestObjectLabel,
+            () => facts.Colliding,
+            () => facts.CollisionWireframesVisible,
+            () => facts.StreamingRadius,
+            () => facts.MouseSensitivity,
+            () => facts.ChaseDistance,
+            () => facts.RmbOrbitHeld,
+            () => facts.HourName,
+            () => facts.DayFraction,
+            () => facts.Weather,
+            () => facts.ActiveLights,
+            () => facts.RegisteredLights,
+            () => facts.ParticleCount,
+            () => facts.Fps,
+            () => facts.FrameMilliseconds,
+            _dependencies.Combat);
+    }
+
+    private static bool HasIncompleteCleanup(Exception failure)
+    {
+        if (failure is ImGuiBootstrapperConstructionException)
+            return true;
+        if (failure is IRetryableResourceCleanup cleanup
+            && !cleanup.IsCleanupComplete)
+        {
+            return true;
+        }
+        if (failure is AggregateException aggregate)
+            return aggregate.InnerExceptions.Any(HasIncompleteCleanup);
+        return failure.InnerException is { } inner && HasIncompleteCleanup(inner);
+    }
+
+    private void Fault(SettingsDevToolsCompositionPoint point) =>
+        _faultInjection?.Invoke(point);
+}

src/AcDream.App/Input/PlayerModeController.cs

@@ -17,7 +17,9 @@ namespace AcDream.App.Input;
 /// chase-camera lifetimes. The window host wires this owner but never mutates
 /// those slots directly.
 /// </summary>
-internal sealed class PlayerModeController : ILocalPlayerTeleportModeOperations
+internal sealed class PlayerModeController :
+    ILocalPlayerTeleportModeOperations,
+    IDevToolsPlayerModeTarget
 {
     private readonly LocalPlayerModeState _mode;
     private readonly LocalPlayerControllerSlot _controllerSlot;

src/AcDream.App/Input/QuiescentInputContext.cs

@@ -4,13 +4,20 @@ using Silk.NET.Input;
 
 namespace AcDream.App.Input;
 
+internal interface IDevToolsInputContext : IInputContext, IDisposable
+{
+    bool IsDisposalComplete { get; }
+    void Activate();
+    void Deactivate();
+}
+
 /// <summary>
 /// Non-owning input-context view for third-party frontends such as Silk's
 /// ImGuiController. It interposes named device relays so frontend callbacks can
 /// be silenced before a long live-session close and physically detached later,
 /// without disposing the canonical Silk input context.
 /// </summary>
-internal sealed class QuiescentInputContext : IInputContext
+internal sealed class QuiescentInputContext : IDevToolsInputContext
 {
     private readonly IInputContext _inner;
     private readonly HostQuiescenceGate _quiescence;

src/AcDream.App/Rendering/DevToolsFramePresenter.cs

@@ -32,7 +32,7 @@ internal interface IDevToolsFrameLifecycle : IRenderFrameFailureRecovery
     void Render(double deltaSeconds, int viewportWidth, int viewportHeight);
 }
 
-internal interface IDevToolsFrameBackend
+internal interface IDevToolsFrameBackend : IDisposable
 {
     void BeginFrame(float deltaSeconds);
 
@@ -93,12 +93,12 @@ internal interface IDevToolsPanelSet
 /// <summary>Concrete ImGui backend for the developer presentation owner.</summary>
 internal sealed class ImGuiDevToolsFrameBackend : IDevToolsFrameBackend, IDisposable
 {
-    private readonly ImGuiBootstrapper _bootstrap;
+    private readonly IImGuiBootstrapper _bootstrap;
     private readonly ImGuiPanelHost _panels;
     private bool _disposed;
 
     public ImGuiDevToolsFrameBackend(
-        ImGuiBootstrapper bootstrap,
+        IImGuiBootstrapper bootstrap,
         ImGuiPanelHost panels)
     {
         _bootstrap = bootstrap ?? throw new ArgumentNullException(nameof(bootstrap));
@@ -157,11 +157,14 @@ internal sealed class ImGuiDevToolsFrameBackend : IDevToolsFrameBackend, IDispos
 internal sealed class DevToolsCameraMenuOperations : IDevToolsCameraMenuOperations
 {
     private readonly CameraController _camera;
-    private PlayerModeController? _playerMode;
+    private readonly IDevToolsPlayerModeCommands _playerMode;
 
-    public DevToolsCameraMenuOperations(CameraController camera)
+    public DevToolsCameraMenuOperations(
+        CameraController camera,
+        IDevToolsPlayerModeCommands playerMode)
     {
         _camera = camera ?? throw new ArgumentNullException(nameof(camera));
+        _playerMode = playerMode ?? throw new ArgumentNullException(nameof(playerMode));
     }
 
     public bool IsFlyMode => _camera.IsFlyMode;
@@ -172,25 +175,41 @@ internal sealed class DevToolsCameraMenuOperations : IDevToolsCameraMenuOperatio
         set => AcDream.Core.Rendering.CameraDiagnostics.CollideCamera = value;
     }
 
-    public void Bind(PlayerModeController playerMode)
+    public void ToggleFlyOrChase() => _playerMode.ToggleFlyOrChase();
-    {
-        _playerMode = playerMode ?? throw new ArgumentNullException(nameof(playerMode));
-    }
-
-    public void ToggleFlyOrChase() => _playerMode?.ToggleFlyOrChase();
 }
 
 /// <summary>Resolves the reconnect-safe command bus at draw time.</summary>
 internal sealed class DevToolsCommandBusSource : IDevToolsCommandBusSource
 {
     private LiveSessionController? _session;
+    private bool _deactivated;
 
     public ICommandBus Current =>
-        _session?.Commands ?? NullCommandBus.Instance;
+        !_deactivated && _session is { } session
+            ? session.Commands
+            : NullCommandBus.Instance;
 
     public void Bind(LiveSessionController session)
     {
-        _session = session ?? throw new ArgumentNullException(nameof(session));
+        ArgumentNullException.ThrowIfNull(session);
+        ObjectDisposedException.ThrowIf(_deactivated, this);
+        if (_session is not null && !ReferenceEquals(_session, session))
+            throw new InvalidOperationException(
+                "Developer command-bus authority is already bound.");
+        _session = session;
+    }
+
+    public void Unbind(LiveSessionController session)
+    {
+        ArgumentNullException.ThrowIfNull(session);
+        if (ReferenceEquals(_session, session))
+            _session = null;
+    }
+
+    public void Deactivate()
+    {
+        _deactivated = true;
+        _session = null;
     }
 }
 

src/AcDream.App/Rendering/DevToolsRuntimeSources.cs

@@ -0,0 +1,289 @@
+using System.Numerics;
+using AcDream.App.Input;
+using AcDream.App.Physics;
+using AcDream.App.Streaming;
+using AcDream.App.World;
+using AcDream.Core.Lighting;
+using AcDream.Core.Physics;
+using AcDream.Core.Vfx;
+
+namespace AcDream.App.Rendering;
+
+internal interface IRenderFrameDiagnosticsSnapshotSource
+{
+    RenderFrameDiagnosticsSnapshot Snapshot { get; }
+}
+
+/// <summary>
+/// Phase-3 view over the Phase-6 diagnostics owner. Before that owner exists,
+/// consumers see the same 60 Hz seed used by the former null-safe closures.
+/// </summary>
+internal sealed class DeferredRenderFrameDiagnosticsSource
+    : IRenderFrameDiagnosticsSnapshotSource
+{
+    private IRenderFrameDiagnosticsSnapshotSource? _target;
+    private bool _deactivated;
+
+    public RenderFrameDiagnosticsSnapshot Snapshot =>
+        !_deactivated && _target is { } target
+            ? target.Snapshot
+            : RenderFrameDiagnosticsSnapshot.Initial;
+
+    public void Bind(IRenderFrameDiagnosticsSnapshotSource target)
+    {
+        ArgumentNullException.ThrowIfNull(target);
+        ObjectDisposedException.ThrowIf(_deactivated, this);
+        if (_target is not null && !ReferenceEquals(_target, target))
+            throw new InvalidOperationException(
+                "Render-frame diagnostics are already bound.");
+        _target = target;
+    }
+
+    public void Unbind(IRenderFrameDiagnosticsSnapshotSource target)
+    {
+        ArgumentNullException.ThrowIfNull(target);
+        if (ReferenceEquals(_target, target))
+            _target = null;
+    }
+
+    public void Deactivate()
+    {
+        _deactivated = true;
+        _target = null;
+    }
+}
+
+internal interface ICanonicalWorldEntityCountSource
+{
+    int EntityCount { get; }
+}
+
+/// <summary>
+/// Prevents early developer UI from retaining the empty bootstrap
+/// <see cref="GpuWorldState"/> that is replaced during Phase 6.
+/// </summary>
+internal sealed class DeferredCanonicalWorldEntityCountSource
+    : ICanonicalWorldEntityCountSource
+{
+    private GpuWorldState? _target;
+    private bool _deactivated;
+
+    public int EntityCount => !_deactivated ? _target?.Entities.Count ?? 0 : 0;
+
+    public void Bind(GpuWorldState target)
+    {
+        ArgumentNullException.ThrowIfNull(target);
+        ObjectDisposedException.ThrowIf(_deactivated, this);
+        if (_target is not null && !ReferenceEquals(_target, target))
+            throw new InvalidOperationException(
+                "The canonical world entity-count source is already bound.");
+        _target = target;
+    }
+
+    public void Unbind(GpuWorldState target)
+    {
+        ArgumentNullException.ThrowIfNull(target);
+        if (ReferenceEquals(_target, target))
+            _target = null;
+    }
+
+    public void Deactivate()
+    {
+        _deactivated = true;
+        _target = null;
+    }
+}
+
+internal interface IDevToolsPlayerModeCommands
+{
+    void ToggleFlyOrChase();
+}
+
+internal interface IDevToolsPlayerModeTarget
+{
+    void ToggleFlyOrChase();
+}
+
+/// <summary>Phase-3 command edge resolved by the Phase-7 player owner.</summary>
+internal sealed class DeferredDevToolsPlayerModeCommands
+    : IDevToolsPlayerModeCommands
+{
+    private IDevToolsPlayerModeTarget? _target;
+    private bool _deactivated;
+
+    public void Bind(IDevToolsPlayerModeTarget target)
+    {
+        ArgumentNullException.ThrowIfNull(target);
+        ObjectDisposedException.ThrowIf(_deactivated, this);
+        if (_target is not null && !ReferenceEquals(_target, target))
+            throw new InvalidOperationException(
+                "Developer player-mode commands are already bound.");
+        _target = target;
+    }
+
+    public void Unbind(IDevToolsPlayerModeTarget target)
+    {
+        ArgumentNullException.ThrowIfNull(target);
+        if (ReferenceEquals(_target, target))
+            _target = null;
+    }
+
+    public void Deactivate()
+    {
+        _deactivated = true;
+        _target = null;
+    }
+
+    public void ToggleFlyOrChase()
+    {
+        if (!_deactivated)
+            _target?.ToggleFlyOrChase();
+    }
+}
+
+internal interface IDevToolsRuntimeFacts
+{
+    Vector3 PlayerPosition { get; }
+    float PlayerHeadingDegrees { get; }
+    uint PlayerCellId { get; }
+    bool PlayerOnGround { get; }
+    bool InPlayerMode { get; }
+    bool InFlyMode { get; }
+    float VerticalVelocity { get; }
+    int EntityCount { get; }
+    int AnimatedCount { get; }
+    int VisibleLandblocks { get; }
+    int TotalLandblocks { get; }
+    int ShadowObjectCount { get; }
+    float NearestObjectDistance { get; }
+    string NearestObjectLabel { get; }
+    bool Colliding { get; }
+    bool CollisionWireframesVisible { get; }
+    int StreamingRadius { get; }
+    float MouseSensitivity { get; }
+    float ChaseDistance { get; }
+    bool RmbOrbitHeld { get; }
+    string HourName { get; }
+    float DayFraction { get; }
+    string Weather { get; }
+    int ActiveLights { get; }
+    int RegisteredLights { get; }
+    int ParticleCount { get; }
+    float Fps { get; }
+    float FrameMilliseconds { get; }
+}
+
+/// <summary>
+/// Read-only developer presentation model assembled from focused canonical
+/// owners. It caches no world, player, frame, or environment values.
+/// </summary>
+internal sealed class DevToolsRuntimeFacts : IDevToolsRuntimeFacts
+{
+    private readonly ILocalPlayerModeSource _mode;
+    private readonly ILocalPlayerControllerSource _player;
+    private readonly CameraController _camera;
+    private readonly ICanonicalWorldEntityCountSource _world;
+    private readonly LiveEntityAnimationRuntimeView<LiveEntityAnimationState> _animations;
+    private readonly IDebugVmRenderFactsSource _renderFacts;
+    private readonly PhysicsEngine _physics;
+    private readonly IWorldSceneDebugStateSource _sceneDebug;
+    private readonly IWorldRenderRangeSource _renderRange;
+    private readonly CameraPointerInputController? _pointer;
+    private readonly WorldEnvironmentController _environment;
+    private readonly LightManager _lights;
+    private readonly ParticleSystem _particles;
+    private readonly IRenderFrameDiagnosticsSnapshotSource _frame;
+
+    public DevToolsRuntimeFacts(
+        ILocalPlayerModeSource mode,
+        ILocalPlayerControllerSource player,
+        CameraController camera,
+        ICanonicalWorldEntityCountSource world,
+        LiveEntityAnimationRuntimeView<LiveEntityAnimationState> animations,
+        IDebugVmRenderFactsSource renderFacts,
+        PhysicsEngine physics,
+        IWorldSceneDebugStateSource sceneDebug,
+        IWorldRenderRangeSource renderRange,
+        CameraPointerInputController? pointer,
+        WorldEnvironmentController environment,
+        LightManager lights,
+        ParticleSystem particles,
+        IRenderFrameDiagnosticsSnapshotSource frame)
+    {
+        _mode = mode ?? throw new ArgumentNullException(nameof(mode));
+        _player = player ?? throw new ArgumentNullException(nameof(player));
+        _camera = camera ?? throw new ArgumentNullException(nameof(camera));
+        _world = world ?? throw new ArgumentNullException(nameof(world));
+        _animations = animations ?? throw new ArgumentNullException(nameof(animations));
+        _renderFacts = renderFacts ?? throw new ArgumentNullException(nameof(renderFacts));
+        _physics = physics ?? throw new ArgumentNullException(nameof(physics));
+        _sceneDebug = sceneDebug ?? throw new ArgumentNullException(nameof(sceneDebug));
+        _renderRange = renderRange ?? throw new ArgumentNullException(nameof(renderRange));
+        _pointer = pointer;
+        _environment = environment ?? throw new ArgumentNullException(nameof(environment));
+        _lights = lights ?? throw new ArgumentNullException(nameof(lights));
+        _particles = particles ?? throw new ArgumentNullException(nameof(particles));
+        _frame = frame ?? throw new ArgumentNullException(nameof(frame));
+    }
+
+    public Vector3 PlayerPosition
+    {
+        get
+        {
+            if (_mode.IsPlayerMode && _player.Controller is { } player)
+                return player.Position;
+            Matrix4x4.Invert(_camera.Active.View, out Matrix4x4 inverse);
+            return new Vector3(inverse.M41, inverse.M42, inverse.M43);
+        }
+    }
+
+    public float PlayerHeadingDegrees
+    {
+        get
+        {
+            float degrees;
+            if (_mode.IsPlayerMode && _player.Controller is { } player)
+            {
+                degrees = player.Yaw * (180f / MathF.PI);
+            }
+            else
+            {
+                Matrix4x4.Invert(_camera.Active.View, out Matrix4x4 inverse);
+                var forward = new Vector3(-inverse.M31, -inverse.M32, -inverse.M33);
+                degrees = MathF.Atan2(forward.Y, forward.X) * (180f / MathF.PI);
+            }
+
+            degrees %= 360f;
+            return degrees < 0f ? degrees + 360f : degrees;
+        }
+    }
+
+    public uint PlayerCellId =>
+        _mode.IsPlayerMode ? _player.Controller?.CellId ?? 0u : 0u;
+    public bool PlayerOnGround =>
+        _mode.IsPlayerMode && _player.Controller is { IsAirborne: false };
+    public bool InPlayerMode => _mode.IsPlayerMode;
+    public bool InFlyMode => _camera.IsFlyMode;
+    public float VerticalVelocity => _player.Controller?.VerticalVelocity ?? 0f;
+    public int EntityCount => _world.EntityCount;
+    public int AnimatedCount => _animations.Count;
+    public int VisibleLandblocks => _renderFacts.DebugVmFacts.VisibleLandblocks;
+    public int TotalLandblocks => _renderFacts.DebugVmFacts.TotalLandblocks;
+    public int ShadowObjectCount => _physics.ShadowObjects.TotalRegistered;
+    public float NearestObjectDistance => _renderFacts.DebugVmFacts.NearestObjectDistance;
+    public string NearestObjectLabel => _renderFacts.DebugVmFacts.NearestObjectLabel;
+    public bool Colliding => _renderFacts.DebugVmFacts.Colliding;
+    public bool CollisionWireframesVisible => _sceneDebug.CollisionWireframesVisible;
+    public int StreamingRadius => _renderRange.NearRadius;
+    public float MouseSensitivity => _pointer?.ActiveSensitivity ?? 1f;
+    public float ChaseDistance => _camera.Chase?.Distance ?? 0f;
+    public bool RmbOrbitHeld => _pointer?.RmbOrbitHeld ?? false;
+    public string HourName => _environment.WorldTime.CurrentCalendar.Hour.ToString();
+    public float DayFraction => (float)_environment.WorldTime.DayFraction;
+    public string Weather => _environment.Weather.Kind.ToString();
+    public int ActiveLights => _lights.ActiveCount;
+    public int RegisteredLights => _lights.RegisteredCount;
+    public int ParticleCount => _particles.ActiveParticleCount;
+    public float Fps => (float)_frame.Snapshot.Fps;
+    public float FrameMilliseconds => (float)_frame.Snapshot.FrameMilliseconds;
+}

src/AcDream.App/Rendering/FramebufferResizeController.cs

@@ -50,6 +50,31 @@ internal sealed class DevToolsFramebufferTarget(DevToolsFramePresenter presenter
             DevToolsPanelLayoutCondition.Always);
 }
 
+/// <summary>Expected-owner lease for the optional Phase-3 resize edge.</summary>
+internal sealed class FramebufferDevToolsBinding : IDisposable
+{
+    private readonly FramebufferResizeController _owner;
+    private readonly IFramebufferDevToolsTarget _target;
+    private bool _disposed;
+
+    public FramebufferDevToolsBinding(
+        FramebufferResizeController owner,
+        IFramebufferDevToolsTarget target)
+    {
+        _owner = owner ?? throw new ArgumentNullException(nameof(owner));
+        _target = target ?? throw new ArgumentNullException(nameof(target));
+        _owner.BindDevTools(_target);
+    }
+
+    public void Dispose()
+    {
+        if (_disposed)
+            return;
+        _owner.UnbindDevTools(_target);
+        _disposed = true;
+    }
+}
+
 /// <summary>
 /// The one framebuffer-size target. Logical gameplay/UI dimensions continue
 /// to come from Window.Size; this owner only applies physical framebuffer

src/AcDream.App/Rendering/GameWindow.cs

@@ -16,7 +16,8 @@ public sealed class GameWindow :
     IDisposable,
     IGameWindowPlatformPublication<GL, IInputContext>,
     IGameWindowHostInputCameraPublication,
-    IGameWindowContentEffectsAudioPublication
+    IGameWindowContentEffectsAudioPublication,
+    IGameWindowSettingsDevToolsPublication
 {
     private static double ClientTimerNow() =>
         System.Diagnostics.Stopwatch.GetTimestamp()
@@ -33,7 +34,6 @@ public sealed class GameWindow :
     private SilkWindowCallbackBinding? _windowCallbacks;
     private GL? _gl;
     private IInputContext? _input;
-    private AcDream.App.Input.QuiescentInputContext? _devToolsInputContext;
     private TerrainModernRenderer? _terrain;
     /// <summary>Phase N.5b: terrain_modern.vert/.frag program. Owned by
     /// <see cref="_terrain"/> at draw time but allocated + disposed here.</summary>
@@ -345,10 +345,9 @@ public sealed class GameWindow :
 
     // Phase D.2a — ImGui devtools UI overlay. Null unless ACDREAM_DEVTOOLS=1.
     // See docs/plans/2026-04-24-ui-framework.md for the staged UI strategy.
-    private AcDream.App.Rendering.ImGuiDevToolsFrameBackend? _devToolsBackend;
     private AcDream.App.Rendering.DevToolsFramePresenter? _devToolsFramePresenter;
-    private AcDream.App.Rendering.DevToolsCameraMenuOperations? _devToolsCameraMenu;
     private AcDream.App.Rendering.DevToolsCommandBusSource? _devToolsCommandBus;
+    private DevToolsCompositionOwner? _devToolsComposition;
     private AcDream.UI.Abstractions.Panels.Vitals.VitalsVM? _vitalsVm;
     private AcDream.UI.Abstractions.Panels.Chat.ChatVM? _retailChatVm;
     // Phase D.2b — retained host + composition runtime. Null unless ACDREAM_RETAIL_UI=1.
@@ -434,7 +433,6 @@ public sealed class GameWindow :
     private readonly AcDream.App.Input.LocalPlayerSkillState _localPlayerSkills = new();
     private readonly AcDream.App.Input.ViewportAspectState _viewportAspect = new();
     private readonly FramebufferResizeController _framebufferResize;
-    private IFramebufferDevToolsTarget? _framebufferDevToolsTarget;
     private AcDream.App.Input.PlayerModeController? _playerModeController;
     private readonly AcDream.App.Interaction.PlayerApproachCompletionState
         _playerApproachCompletions = new();
@@ -784,6 +782,26 @@ public sealed class GameWindow :
         _audioSink = value.HookSink;
     }
 
+    void IGameWindowSettingsDevToolsPublication.PublishDevTools(
+        DevToolsCompositionOwner value)
+    {
+        ArgumentNullException.ThrowIfNull(value);
+        if (_devToolsComposition is not null
+            || _devToolsFramePresenter is not null
+            || _devToolsCommandBus is not null
+            || _debugVm is not null)
+        {
+            throw new InvalidOperationException(
+                "The GameWindow composition shell already owns developer tools.");
+        }
+
+        _devToolsComposition = value;
+        _devToolsFramePresenter = value.Presenter;
+        _devToolsCommandBus = value.CommandBus;
+        _vitalsVm = value.Vitals;
+        _debugVm = value.Debug;
+    }
+
     private static void PublishCompositionOwner<T>(
         ref T? destination,
         T value,
@@ -856,6 +874,64 @@ public sealed class GameWindow :
                     Console.Error.WriteLine),
                 this).Compose(platform, hostInputCamera);
 
+        SettingsDevToolsOptionalDependencies? optionalDevTools = null;
+        if (DevToolsEnabled)
+        {
+            var devToolsWorldEntities =
+                new DeferredCanonicalWorldEntityCountSource();
+            var devToolsFrameDiagnostics =
+                new DeferredRenderFrameDiagnosticsSource();
+            var devToolsPlayerModeCommands =
+                new DeferredDevToolsPlayerModeCommands();
+            var devToolsFacts = new DevToolsRuntimeFacts(
+                _localPlayerMode,
+                _playerControllerSlot,
+                hostInputCamera.CameraController,
+                devToolsWorldEntities,
+                _animatedEntities,
+                _debugVmRenderFacts,
+                _physicsEngine,
+                _worldSceneDebugState,
+                _renderRange,
+                hostInputCamera.CameraPointerInput,
+                _worldEnvironment,
+                Lighting,
+                contentEffectsAudio.ParticleSystem,
+                devToolsFrameDiagnostics);
+            IRuntimeKeyBindingTarget? keyBindingTarget =
+                hostInputCamera.InputDispatcher is { } settingsDispatcher
+                    ? new RuntimeKeyBindingTarget(settingsDispatcher)
+                    : null;
+            optionalDevTools = new SettingsDevToolsOptionalDependencies(
+                devToolsFacts,
+                keyBindingTarget,
+                devToolsWorldEntities,
+                devToolsFrameDiagnostics,
+                devToolsPlayerModeCommands);
+        }
+        SettingsDevToolsResult settingsDevTools =
+            new SettingsDevToolsCompositionPhase(
+                new SettingsDevToolsDependencies(
+                    _window!,
+                    _runtimeSettings,
+                    new RuntimeSettingsStartupTargets(
+                        new SilkRuntimeDisplayWindowTarget(_window!),
+                        _displayFramePacing,
+                        hostInputCamera.CameraController,
+                        contentEffectsAudio.Audio?.Engine),
+                    _hostQuiescence,
+                    Chat,
+                    Combat,
+                    LocalPlayer,
+                    optionalDevTools,
+                    _runtimeDiagnosticCommands,
+                    _combatFeedback,
+                    _keyBindings,
+                    _frameProfiler,
+                    _framebufferResize,
+                    Console.WriteLine),
+                this).Compose(platform, hostInputCamera, contentEffectsAudio);
+
         _gl.ClearColor(0.05f, 0.10f, 0.18f, 1.0f);
         _gl.Enable(EnableCap.DepthTest);
 
@@ -906,222 +982,6 @@ public sealed class GameWindow :
             Console.WriteLine("world-hud font: no system monospace font found");
         }
 
-        // Settings are runtime state, not devtools state. Apply the immutable
-        // pre-window snapshot once after camera/audio exist and before any
-        // optional frontend or world/render factory consumes it.
-        _runtimeSettings.ApplyStartup(
-            new RuntimeSettingsStartupTargets(
-                new SilkRuntimeDisplayWindowTarget(_window!),
-                _displayFramePacing,
-                _cameraController!,
-                _audioEngine));
-
-        // Phase D.2a — ImGui devtools overlay. Zero cost when the env var
-        // isn't set: no context creation, no per-frame branches hit.
-        // See docs/plans/2026-04-24-ui-framework.md + memory/project_ui_architecture.md.
-        if (DevToolsEnabled)
-        {
-            AcDream.UI.ImGui.ImGuiBootstrapper? imguiBootstrap = null;
-            AcDream.UI.Abstractions.Panels.Settings.SettingsVM? settingsVm = null;
-            try
-            {
-                _devToolsInputContext = new AcDream.App.Input.QuiescentInputContext(
-                    _input!,
-                    _hostQuiescence);
-                imguiBootstrap =
-                    new AcDream.UI.ImGui.ImGuiBootstrapper(
-                        _gl!,
-                        _window!,
-                        _devToolsInputContext);
-                _devToolsInputContext.Activate();
-                var panelHost = new AcDream.UI.ImGui.ImGuiPanelHost();
-
-                // VitalsVM: GUID=0 at construction; set later at EnterWorld
-                // (see the _playerServerGuid assignment path). Pre-login the
-                // HP bar just reads 1.0 (safe default) — harmless. Stam/Mana
-                // bars surface only after the first PlayerDescription has
-                // populated LocalPlayer (Issue #5).
-                _vitalsVm = new AcDream.UI.Abstractions.Panels.Vitals.VitalsVM(Combat, LocalPlayer);
-                var vitalsPanel =
-                    new AcDream.UI.Abstractions.Panels.Vitals.VitalsPanel(_vitalsVm);
-                panelHost.Register(vitalsPanel);
-
-                // ChatPanel: reads the tail of the shared ChatLog. No GUID
-                // dependency — works pre-login (empty) and post-login (live
-                // tail of received speech/tells/channels/system msgs).
-                // FpsProvider + PositionProvider plumb the runtime state
-                // the client-side /framerate and /loc commands need; the
-                // panel asks the VM, the VM asks GameWindow via these
-                // delegates, no panel-vs-renderer-vs-state coupling.
-                var chatVm = new AcDream.UI.Abstractions.Panels.Chat.ChatVM(Chat)
-                {
-                    FpsProvider = () =>
-                        (float)(_renderFrameDiagnostics?.Snapshot.Fps ?? 60.0),
-                    PositionProvider = () => GetDebugPlayerPosition(),
-                };
-                var chatPanel = new AcDream.UI.Abstractions.Panels.Chat.ChatPanel(chatVm);
-                panelHost.Register(chatPanel);
-
-                // Phase I.2: DebugPanel — replaces the deleted custom
-                // DebugOverlay (six floating panels + hint bar + toast).
-                // The VM closes over every data source the old snapshot
-                // record exposed; reads are live (no per-frame snapshot
-                // build). Action hooks tie the panel's cycle/toggle
-                // buttons back to the same routines the F2/F7/F10
-                // keybinds use.
-                _debugVm = new AcDream.UI.Abstractions.Panels.Debug.DebugVM(
-                    getPlayerPosition: () => GetDebugPlayerPosition(),
-                    getPlayerHeadingDeg: () => GetDebugPlayerHeadingDeg(),
-                    getPlayerCellId: () => GetDebugPlayerCellId(),
-                    getPlayerOnGround: () => GetDebugPlayerOnGround(),
-                    getInPlayerMode: () => _playerMode,
-                    getInFlyMode: () => _cameraController?.IsFlyMode ?? false,
-                    getVerticalVelocity: () => _playerController?.VerticalVelocity ?? 0f,
-                    getEntityCount: () => _worldState.Entities.Count,
-                    getAnimatedCount: () => _animatedEntities.Count,
-                    getLandblocksVisible: () =>
-                        _debugVmRenderFacts.DebugVmFacts.VisibleLandblocks,
-                    getLandblocksTotal: () =>
-                        _debugVmRenderFacts.DebugVmFacts.TotalLandblocks,
-                    getShadowObjectCount: () => _physicsEngine.ShadowObjects.TotalRegistered,
-                    getNearestObjDist: () =>
-                        _debugVmRenderFacts.DebugVmFacts.NearestObjectDistance,
-                    getNearestObjLabel: () =>
-                        _debugVmRenderFacts.DebugVmFacts.NearestObjectLabel,
-                    getColliding: () =>
-                        _debugVmRenderFacts.DebugVmFacts.Colliding,
-                    getDebugWireframes: () =>
-                        _worldSceneDebugState.CollisionWireframesVisible,
-                    getStreamingRadius: () => _nearRadius,   // A.5 T16 follow-up: was _streamingRadius (legacy single-tier); show near tier
-
-                    getMouseSensitivity: () =>
-                        _cameraPointerInput?.ActiveSensitivity ?? 1f,
-                    getChaseDistance: () => _chaseCamera?.Distance ?? 0f,
-                    getRmbOrbit: () =>
-                        _cameraPointerInput?.RmbOrbitHeld ?? false,
-                    getHourName: () => WorldTime.CurrentCalendar.Hour.ToString(),
-                    getDayFraction: () => (float)WorldTime.DayFraction,
-                    getWeather: () => Weather.Kind.ToString(),
-                    getActiveLights: () => Lighting.ActiveCount,
-                    getRegisteredLights: () => Lighting.RegisteredCount,
-                    getParticleCount: () => _particleSystem?.ActiveParticleCount ?? 0,
-                    getFps: () =>
-                        (float)(_renderFrameDiagnostics?.Snapshot.Fps ?? 60.0),
-                    getFrameMs: () =>
-                        (float)(_renderFrameDiagnostics?.Snapshot.FrameMilliseconds ?? 16.7),
-                    combat: Combat);
-                _debugVm.CycleTimeOfDay =
-                    _runtimeDiagnosticCommands.CycleTimeOfDay;
-                _debugVm.CycleWeather =
-                    _runtimeDiagnosticCommands.CycleWeather;
-                _debugVm.ToggleCollisionWires =
-                    _runtimeDiagnosticCommands.ToggleCollisionWireframes;
-                // Phase K.2: free-fly toggle button — same routine the
-                // legacy F-key alias hits. Cancels the one-shot
-                // auto-entry if the user opts out of player mode before
-                // it fires, so the chase camera doesn't snap on top of
-                // the fly camera mid-inspection.
-                _debugVm.ToggleFlyMode = () =>
-                    _playerModeController?.ToggleFlyOrChase();
-                _combatFeedback.ViewModel = _debugVm;
-                var debugPanel =
-                    new AcDream.UI.Abstractions.Panels.Debug.DebugPanel(_debugVm);
-                panelHost.Register(debugPanel);
-
-                // Phase K.3 — Settings panel. SettingsVM owns a draft
-                // copy of the active KeyBindings. Save replaces the
-                // dispatcher's live table + writes JSON; Cancel reverts
-                // the draft. Construction is null-safe vs. the
-                // dispatcher because the dispatcher is built earlier in
-                // the same OnLoad path (see _inputDispatcher field).
-                AcDream.UI.Abstractions.Panels.Settings.SettingsPanel? settingsPanel = null;
-                if (_inputDispatcher is not null)
-                {
-                    settingsVm = _runtimeSettings.CreateViewModel(
-                        _keyBindings,
-                        _inputDispatcher,
-                        bindings =>
-                        {
-                            _inputDispatcher.SetBindings(bindings);
-                            try
-                            {
-                                bindings.SaveToFile(
-                                    AcDream.UI.Abstractions.Input.KeyBindings.DefaultPath());
-                                Console.WriteLine(
-                                    "keybinds: saved to "
-                                    + AcDream.UI.Abstractions.Input.KeyBindings.DefaultPath());
-                            }
-                            catch (Exception ex)
-                            {
-                                Console.WriteLine($"keybinds: save failed: {ex.Message}");
-                            }
-                        });
-                    settingsPanel =
-                        new AcDream.UI.Abstractions.Panels.Settings.SettingsPanel(settingsVm);
-                    panelHost.Register(settingsPanel);
-                }
-
-                Console.WriteLine("devtools: ImGui panel host ready (VitalsPanel + ChatPanel + DebugPanel + SettingsPanel registered)");
-
-                // L.0 Display tab: seed sensible default positions for
-                // every registered panel. cond=FirstUseEver means imgui.ini
-                // takes precedence on subsequent launches — the user's
-                // dragged positions persist. Without this, the first-run
-                // experience stacks every panel at (0,0) which looks
-                // broken.
-                _devToolsBackend = new AcDream.App.Rendering.ImGuiDevToolsFrameBackend(
-                    imguiBootstrap,
-                    panelHost);
-                _devToolsCameraMenu =
-                    new AcDream.App.Rendering.DevToolsCameraMenuOperations(
-                        _cameraController!);
-                _devToolsCommandBus =
-                    new AcDream.App.Rendering.DevToolsCommandBusSource();
-                _devToolsFramePresenter =
-                    new AcDream.App.Rendering.DevToolsFramePresenter(
-                        _devToolsBackend,
-                        _devToolsCameraMenu,
-                        _devToolsCommandBus,
-                        _frameProfiler,
-                        new AcDream.App.Rendering.DevToolsPanelSet(
-                            vitalsPanel,
-                            chatPanel,
-                            debugPanel,
-                            _debugVm,
-                            settingsPanel));
-                _framebufferDevToolsTarget = new DevToolsFramebufferTarget(
-                    _devToolsFramePresenter);
-                _framebufferResize.BindDevTools(_framebufferDevToolsTarget);
-                _devToolsFramePresenter.ResetLayout(
-                    _window!.Size.X,
-                    _window.Size.Y,
-                    AcDream.App.Rendering.DevToolsPanelLayoutCondition.FirstUseEver);
-            }
-            catch (Exception ex)
-            {
-                Console.WriteLine($"devtools: ImGui init failed: {ex.Message} — devtools disabled");
-                // The focused backend borrows the bootstrap during normal
-                // operation. Construction failure still owns this local and
-                // must release it before abandoning the optional frontend.
-                imguiBootstrap?.Dispose();
-                if (_framebufferDevToolsTarget is { } framebufferTarget)
-                {
-                    _framebufferResize.UnbindDevTools(framebufferTarget);
-                    _framebufferDevToolsTarget = null;
-                }
-                _devToolsInputContext?.Dispose();
-                _devToolsInputContext = null;
-                _devToolsBackend = null;
-                _devToolsFramePresenter = null;
-                _devToolsCameraMenu = null;
-                _devToolsCommandBus = null;
-                _vitalsVm = null;
-                _combatFeedback.ViewModel = null;
-                _debugVm = null;
-                _runtimeSettings.UnbindViewModel(settingsVm);
-            }
-        }
-
         uint centerLandblockId = 0xA9B4FFFFu;
         Console.WriteLine($"loading world view centered on 0x{centerLandblockId:X8}");
 
@@ -1755,6 +1615,7 @@ public sealed class GameWindow :
                 wbSpawnAdapter,
                 onLandblockUnloaded: _classificationCache.InvalidateLandblock,
                 entityScriptActivator: entityScriptActivator);
+            _devToolsComposition?.LateBindings.WorldEntities.Bind(_worldState);
             _liveEntities = new AcDream.App.World.LiveEntityRuntime(
                 _worldState,
                 new AcDream.App.World.CompositeLiveEntityResourceLifecycle(
@@ -2117,6 +1978,8 @@ public sealed class GameWindow :
                 _renderDiagnosticLog,
                 _options.UiProbeDump,
                 resourceDiagnostics);
+        _devToolsComposition?.LateBindings.FrameDiagnostics.Bind(
+            _renderFrameDiagnostics);
 
         // Apply radii from the same immutable quality snapshot used for the
         // window's MSAA, terrain anisotropy, and dispatcher A2C setup.
@@ -2498,7 +2361,8 @@ public sealed class GameWindow :
             _movementTruthDiagnostics,
             _localPlayerSkills,
             _viewportAspect);
-        _devToolsCameraMenu?.Bind(_playerModeController);
+        _devToolsComposition?.LateBindings.PlayerModeCommands.Bind(
+            _playerModeController);
         _devToolsCommandBus?.Bind(_liveSessionController);
         _playerModeAutoEntry = new AcDream.App.Input.PlayerModeAutoEntry(
             new AcDream.App.Input.LivePlayerModeAutoEntryContext(
@@ -3216,59 +3080,6 @@ public sealed class GameWindow :
     // EXPECTED-DIFF: local sidestep pacing now matches how remotes have
     // always played (w6-cutover-map.md R3).
 
-    // ── Phase I.2 — DebugPanel helpers ────────────────────────────────
-    //
-    // The ImGui DebugPanel reads through DebugVM closures that ask
-    // GameWindow for live state on every frame. The helper methods below
-    // are the *named* targets of those closures (and of the F-key
-    // shortcuts that share the same actions). Keeping them as methods
-    // (vs ad-hoc lambdas where the VM is constructed) means both the
-    // panel button and the keybind run the *same* code, so behavior
-    // can't drift between the two surfaces.
-
-    /// <summary>Player-mode-aware position source for the DebugPanel.</summary>
-    private System.Numerics.Vector3 GetDebugPlayerPosition()
-    {
-        if (_playerMode && _playerController is not null)
-            return _playerController.Position;
-        if (_cameraController?.Active is { } cam)
-        {
-            // Camera world position from inverse of view matrix — same
-            // computation used by the scene-lighting UBO each frame.
-            System.Numerics.Matrix4x4.Invert(cam.View, out var inv);
-            return new System.Numerics.Vector3(inv.M41, inv.M42, inv.M43);
-        }
-        return System.Numerics.Vector3.Zero;
-    }
-
-    /// <summary>Heading in degrees, [0..360). Player yaw in player mode, camera-forward heading otherwise.</summary>
-    private float GetDebugPlayerHeadingDeg()
-    {
-        float deg;
-        if (_playerMode && _playerController is not null)
-        {
-            deg = _playerController.Yaw * (180f / MathF.PI);
-        }
-        else if (_cameraController?.Active is { } cam)
-        {
-            // Camera-relative heading from view matrix forward vector. Use
-            // the same -invView.Mxx convention the snapshot block used.
-            System.Numerics.Matrix4x4.Invert(cam.View, out var inv);
-            var fwd = new System.Numerics.Vector3(-inv.M31, -inv.M32, -inv.M33);
-            deg = MathF.Atan2(fwd.Y, fwd.X) * (180f / MathF.PI);
-        }
-        else
-        {
-            return 0f;
-        }
-        deg %= 360f;
-        if (deg < 0f) deg += 360f;
-        return deg;
-    }
-
-    private uint GetDebugPlayerCellId() =>
-        _playerMode && _playerController is not null ? _playerController.CellId : 0u;
-
     private bool GetDebugPlayerOnGround() =>
         _playerMode && _playerController is not null && !_playerController.IsAirborne;
 
@@ -3419,7 +3230,7 @@ public sealed class GameWindow :
             new("mouse source", () => _mouseSource?.Deactivate()),
             new("keyboard source", () => _kbSource?.Deactivate()),
             new("retained UI input", _retailUiLease.QuiesceInput),
-            new("developer tools input", () => _devToolsInputContext?.Deactivate()),
+            new("developer tools input", () => _devToolsComposition?.DeactivateInput()),
         ]),
         // Live-session reset retires the complete streaming window. Every
         // reset callback owner, especially LandblockStreamer, must remain live
@@ -3473,7 +3284,7 @@ public sealed class GameWindow :
                 _gameplayInputActions = null;
             }),
             new("retained UI input", _retailUiLease.DeactivateInput),
-            new("developer tools input", () => _devToolsInputContext?.Dispose()),
+            new("developer tools input", () => _devToolsComposition?.DetachInput()),
             new("camera pointer", () =>
             {
                 AcDream.App.Input.CameraPointerInputController? pointer =
@@ -3650,17 +3461,17 @@ public sealed class GameWindow :
         [
             new("developer tools", () =>
             {
-                if (_framebufferDevToolsTarget is { } framebufferTarget)
+                DevToolsCompositionOwner? owner = _devToolsComposition;
-                {
+                if (owner is null)
-                    _framebufferResize.UnbindDevTools(framebufferTarget);
+                    return;
-                    _framebufferDevToolsTarget = null;
+                owner.DisposeFrontend();
-                }
+                if (!owner.IsDisposalComplete)
+                    throw new InvalidOperationException(
+                        "Developer-tools cleanup remains incomplete.");
+                _devToolsComposition = null;
                 _devToolsFramePresenter = null;
-                _devToolsCameraMenu = null;
                 _devToolsCommandBus = null;
-                _devToolsBackend?.Dispose();
+                _debugVm = null;
-                _devToolsBackend = null;
-                _devToolsInputContext = null;
             }),
             new("portal tunnel", () =>
             {

src/AcDream.App/Rendering/RenderFrameDiagnosticsController.cs

@@ -137,7 +137,9 @@ internal readonly record struct RenderFrameResourceDiagnosticsSnapshot(
 /// Publishes post-presentation frame statistics. The caller invokes this only after
 /// screenshot capture, preserving the accepted screenshot-before-title/resource order.
 /// </summary>
-internal sealed class RenderFrameDiagnosticsController : IRenderFrameDiagnosticsPhase
+internal sealed class RenderFrameDiagnosticsController :
+    IRenderFrameDiagnosticsPhase,
+    IRenderFrameDiagnosticsSnapshotSource
 {
     internal const double PublicationIntervalSeconds = 0.5;
 

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))

src/AcDream.UI.Abstractions/Panels/Chat/ChatVM.cs

@@ -21,13 +21,14 @@ namespace AcDream.UI.Abstractions.Panels.Chat;
 /// unchanged transcript does not require a queue snapshot each frame.
 /// </para>
 /// </summary>
-public sealed class ChatVM
+public sealed class ChatVM : IDisposable
 {
     /// <summary>Default number of tail entries rendered.</summary>
     public const int DefaultDisplayLimit = 20;
 
     private readonly ChatLog _log;
     private readonly int _displayLimit;
+    private bool _disposed;
 
     /// <summary>
     /// Sender name of the most recent INCOMING Tell. Drives the
@@ -104,6 +105,14 @@ public sealed class ChatVM
             LastOutgoingTellTarget = entry.Sender;
     }
 
+    public void Dispose()
+    {
+        if (_disposed)
+            return;
+        _log.EntryAppended -= OnEntryAppended;
+        _disposed = true;
+    }
+
     /// <summary>
     /// Append a client-side system line to the chat log. Used by
     /// client-handled commands (/help, /clear, future) to surface

src/AcDream.UI.Abstractions/Panels/Debug/DebugVM.cs

@@ -67,7 +67,7 @@ public readonly record struct ToastMessage(
 /// debug panels appear.
 /// </para>
 /// </summary>
-public sealed class DebugVM
+public sealed class DebugVM : IDisposable
 {
     /// <summary>Maximum number of combat-event lines kept in the ring.</summary>
     public const int MaxCombatEvents = 25;
@@ -103,6 +103,8 @@ public sealed class DebugVM
     private readonly Func<int>     _getParticleCount;
     private readonly Func<float>   _getFps;
     private readonly Func<float>   _getFrameMs;
+    private readonly CombatState _combat;
+    private bool _disposed;
 
     private readonly Queue<CombatEventLine> _combatEvents = new();
     private readonly Queue<ToastMessage>    _toasts       = new();
@@ -144,7 +146,7 @@ public sealed class DebugVM
         Func<float>   getFrameMs,
         CombatState   combat)
     {
-        if (combat is null) throw new ArgumentNullException(nameof(combat));
+        _combat = combat ?? throw new ArgumentNullException(nameof(combat));
         _getPlayerPosition    = getPlayerPosition    ?? throw new ArgumentNullException(nameof(getPlayerPosition));
         _getPlayerHeadingDeg  = getPlayerHeadingDeg  ?? throw new ArgumentNullException(nameof(getPlayerHeadingDeg));
         _getPlayerCellId      = getPlayerCellId      ?? throw new ArgumentNullException(nameof(getPlayerCellId));
@@ -177,21 +179,12 @@ public sealed class DebugVM
         // Self-subscribe to combat events. Each one becomes a typed entry
         // in the ring; the panel renders them in TextColored. Replaces
         // the old DebugOverlay.BindCombat side-channel.
-        combat.DamageTaken += d => Push(CombatEventKind.Error,
+        _combat.DamageTaken += OnDamageTaken;
-            $"<< {d.AttackerName} hit you for {d.Damage}{(d.Critical ? " CRIT!" : "")}");
+        _combat.DamageDealtAccepted += OnDamageDealt;
-        combat.DamageDealtAccepted += d => Push(CombatEventKind.Info,
+        _combat.EvadedIncoming += OnEvadedIncoming;
-            $">> you hit {d.DefenderName} for {d.Damage}");
+        _combat.MissedOutgoing += OnMissedOutgoing;
-        combat.EvadedIncoming += attacker => Push(CombatEventKind.Warn,
+        _combat.AttackDone += OnAttackDone;
-            $"<< {attacker}'s attack missed you");
+        _combat.KillLanded += OnKillLanded;
-        combat.MissedOutgoing += defender => Push(CombatEventKind.Info,
-            $">> your attack missed {defender}");
-        combat.AttackDone += (_, weenieError) =>
-        {
-            if (weenieError != 0)
-                Push(CombatEventKind.Error, $"!! attack failed (error 0x{weenieError:X})");
-        };
-        combat.KillLanded += (victim, _) =>
-            Push(CombatEventKind.Info, $"** you killed {victim}");
     }
 
     // ── Read-through value surfaces ───────────────────────────────────
@@ -510,4 +503,46 @@ public sealed class DebugVM
         while (_combatEvents.Count > MaxCombatEvents)
             _combatEvents.Dequeue();
     }
+
+    public void Dispose()
+    {
+        if (_disposed)
+            return;
+
+        _combat.DamageTaken -= OnDamageTaken;
+        _combat.DamageDealtAccepted -= OnDamageDealt;
+        _combat.EvadedIncoming -= OnEvadedIncoming;
+        _combat.MissedOutgoing -= OnMissedOutgoing;
+        _combat.AttackDone -= OnAttackDone;
+        _combat.KillLanded -= OnKillLanded;
+        _disposed = true;
+    }
+
+    private void OnDamageTaken(CombatState.DamageIncoming damage) =>
+        Push(
+            CombatEventKind.Error,
+            $"<< {damage.AttackerName} hit you for {damage.Damage}" +
+            (damage.Critical ? " CRIT!" : string.Empty));
+
+    private void OnDamageDealt(CombatState.DamageDealt damage) =>
+        Push(
+            CombatEventKind.Info,
+            $">> you hit {damage.DefenderName} for {damage.Damage}");
+
+    private void OnEvadedIncoming(string attacker) =>
+        Push(CombatEventKind.Warn, $"<< {attacker}'s attack missed you");
+
+    private void OnMissedOutgoing(string defender) =>
+        Push(CombatEventKind.Info, $">> your attack missed {defender}");
+
+    private void OnAttackDone(uint _, uint weenieError)
+    {
+        if (weenieError != 0)
+            Push(
+                CombatEventKind.Error,
+                $"!! attack failed (error 0x{weenieError:X})");
+    }
+
+    private void OnKillLanded(string victim, uint _) =>
+        Push(CombatEventKind.Info, $"** you killed {victim}");
 }

src/AcDream.UI.ImGui/ImGuiBootstrapper.cs

@@ -28,7 +28,31 @@ namespace AcDream.UI.ImGui;
 /// one of those present. Pivoted to the official Silk.NET extension on 2026-04-25.
 /// </para>
 /// </summary>
-public sealed class ImGuiBootstrapper : IDisposable
+public interface IImGuiBootstrapper : IDisposable
+{
+    void BeginFrame(float deltaSeconds);
+    void Render();
+    void AbortFrame();
+}
+
+/// <summary>
+/// The upstream Silk controller does not expose a partially constructed
+/// instance. A constructor failure therefore requires teardown of the owning
+/// GL/window host instead of being treated as a recoverable optional-frontend
+/// failure.
+/// </summary>
+public sealed class ImGuiBootstrapperConstructionException : Exception
+{
+    internal ImGuiBootstrapperConstructionException(Exception innerException)
+        : base(
+            "Silk ImGui construction did not publish a cleanup owner; " +
+            "the graphics host must be torn down.",
+            innerException)
+    {
+    }
+}
+
+public sealed class ImGuiBootstrapper : IImGuiBootstrapper
 {
     private readonly ImGuiController _controller;
 
@@ -42,7 +66,21 @@ public sealed class ImGuiBootstrapper : IDisposable
         //   - ImGuiOpenGL3 shader + vertex-buffer init (via Silk.NET GL)
         //   - Keyboard + mouse event subscription (bound to Silk.NET IInputContext)
         //   - Default style = dark
-        _controller = new ImGuiController(gl, window, input);
+        nint priorContext = ImGuiNET.ImGui.GetCurrentContext();
+        try
+        {
+            _controller = new ImGuiController(gl, window, input);
+        }
+        catch (Exception failure)
+        {
+            nint partialContext = ImGuiNET.ImGui.GetCurrentContext();
+            if (partialContext != 0 && partialContext != priorContext)
+            {
+                ImGuiNET.ImGui.DestroyContext(partialContext);
+                ImGuiNET.ImGui.SetCurrentContext(priorContext);
+            }
+            throw new ImGuiBootstrapperConstructionException(failure);
+        }
     }
 
     /// <summary>

tests/AcDream.App.Tests/Combat/CombatFeedbackSlotTests.cs

@@ -0,0 +1,59 @@
+using System.Numerics;
+using AcDream.App.Combat;
+using AcDream.Core.Combat;
+using AcDream.UI.Abstractions.Panels.Debug;
+
+namespace AcDream.App.Tests.Combat;
+
+public sealed class CombatFeedbackSlotTests
+{
+    [Fact]
+    public void ExpectedOwnerUnbindCannotClearReplacement()
+    {
+        var slot = new CombatFeedbackSlot();
+        using DebugVM first = CreateViewModel();
+        using DebugVM second = CreateViewModel();
+
+        slot.Bind(first);
+        slot.Unbind(second);
+        slot.Show("first");
+        Assert.Single(first.RecentToasts);
+        Assert.Empty(second.RecentToasts);
+
+        slot.Unbind(first);
+        slot.Bind(second);
+        slot.Show("second");
+        Assert.Single(second.RecentToasts);
+    }
+
+    private static DebugVM CreateViewModel() => new(
+        static () => Vector3.Zero,
+        static () => 0,
+        static () => 0,
+        static () => false,
+        static () => false,
+        static () => false,
+        static () => 0,
+        static () => 0,
+        static () => 0,
+        static () => 0,
+        static () => 0,
+        static () => 0,
+        static () => float.PositiveInfinity,
+        static () => "-",
+        static () => false,
+        static () => false,
+        static () => 0,
+        static () => 1,
+        static () => 0,
+        static () => false,
+        static () => "0",
+        static () => 0,
+        static () => "Clear",
+        static () => 0,
+        static () => 0,
+        static () => 0,
+        static () => 60,
+        static () => 16.7f,
+        new CombatState());
+}

tests/AcDream.App.Tests/Composition/SettingsDevToolsCompositionTests.cs

@@ -0,0 +1,520 @@
+using System.Numerics;
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using AcDream.App.Combat;
+using AcDream.App.Composition;
+using AcDream.App.Diagnostics;
+using AcDream.App.Input;
+using AcDream.App.Rendering;
+using AcDream.App.Settings;
+using AcDream.Core.Chat;
+using AcDream.Core.Combat;
+using AcDream.Core.Player;
+using AcDream.Core.Spells;
+using AcDream.UI.Abstractions.Input;
+using AcDream.UI.Abstractions.Panels.Settings;
+using AcDream.UI.Abstractions.Settings;
+using AcDream.UI.ImGui;
+using Silk.NET.Input;
+using Silk.NET.Maths;
+using Silk.NET.OpenGL;
+using Silk.NET.Windowing;
+
+namespace AcDream.App.Tests.Composition;
+
+public sealed class SettingsDevToolsCompositionTests
+{
+    [Fact]
+    public void DisabledFrontendAppliesSettingsAndAcquiresNothingOptional()
+    {
+        using var fixture = new Fixture(enabled: false);
+
+        SettingsDevToolsResult result = fixture.Compose();
+
+        Assert.Null(result.DevTools);
+        Assert.Equal(1, fixture.Startup.DisplayCalls);
+        Assert.Equal(1, fixture.Startup.AudioCalls);
+        Assert.Equal(0, fixture.Factory.Calls);
+        Assert.Equal(
+            [SettingsDevToolsCompositionPoint.SettingsApplied],
+            fixture.Points);
+    }
+
+    [Fact]
+    public void UnsupportedInputDisablesBeforeAcquiringFrontendResources()
+    {
+        using var fixture = new Fixture(inputSupported: false);
+
+        SettingsDevToolsResult result = fixture.Compose();
+
+        Assert.Null(result.DevTools);
+        Assert.Null(fixture.Factory.Input);
+        Assert.Null(fixture.Factory.Bootstrap);
+        Assert.Equal(1, fixture.Factory.Calls);
+    }
+
+    [Fact]
+    public void EnabledFrontendPublishesOneCompleteOwnerAfterEveryEdge()
+    {
+        using var fixture = new Fixture();
+
+        SettingsDevToolsResult result = fixture.Compose();
+
+        Assert.Same(fixture.Publication.Owner, result.DevTools);
+        Assert.Equal(
+            Enum.GetValues<SettingsDevToolsCompositionPoint>(),
+            fixture.Points);
+        Assert.True(fixture.Factory.Input!.Activated);
+        Assert.Equal(4, fixture.Factory.Backend!.LayoutCalls);
+        Assert.Equal(1, fixture.Publication.PublishCalls);
+    }
+
+    [Theory]
+    [MemberData(nameof(OptionalFailurePoints))]
+    public void OptionalPrefixFailureDisablesOnlyAfterCompleteReverseCleanup(
+        int pointValue)
+    {
+        var point = (SettingsDevToolsCompositionPoint)pointValue;
+        using var fixture = new Fixture(failurePoint: point);
+
+        SettingsDevToolsResult result = fixture.Compose();
+
+        Assert.Null(result.DevTools);
+        Assert.Null(fixture.Publication.Owner);
+        Assert.Equal(
+            Enum.GetValues<SettingsDevToolsCompositionPoint>()
+                .TakeWhile(candidate => candidate <= point),
+            fixture.Points);
+        if (fixture.Factory.Input is { } input)
+            Assert.True(input.IsDisposalComplete);
+        if (fixture.Factory.Bootstrap is { } bootstrap)
+            Assert.Equal(1, bootstrap.DisposeCalls);
+        if (fixture.Factory.Backend is { } backend)
+            Assert.Equal(1, backend.DisposeCalls);
+    }
+
+    public static TheoryData<int> OptionalFailurePoints()
+    {
+        var data = new TheoryData<int>();
+        foreach (SettingsDevToolsCompositionPoint point in
+                 Enum.GetValues<SettingsDevToolsCompositionPoint>())
+        {
+            if (point is SettingsDevToolsCompositionPoint.SettingsApplied
+                or SettingsDevToolsCompositionPoint.DevToolsPublished)
+            {
+                continue;
+            }
+            data.Add((int)point);
+        }
+        return data;
+    }
+
+    [Fact]
+    public void FailureAfterPublicationPropagatesToLifetimeOwner()
+    {
+        using var fixture = new Fixture(
+            failurePoint: SettingsDevToolsCompositionPoint.DevToolsPublished);
+
+        Assert.Throws<InvalidOperationException>(fixture.Compose);
+
+        Assert.NotNull(fixture.Publication.Owner);
+        Assert.False(fixture.Publication.Owner!.IsDisposalComplete);
+    }
+
+    [Fact]
+    public void CleanupFailurePropagatesAndRetrySkipsCompletedOperations()
+    {
+        using var fixture = new Fixture(
+            failurePoint: SettingsDevToolsCompositionPoint.InitialLayoutApplied,
+            backendDisposeFailures: 1);
+
+        var failure = Assert.Throws<CompositionAcquisitionException>(fixture.Compose);
+        Assert.False(failure.IsCleanupComplete);
+        Assert.Equal(1, fixture.Factory.Backend!.DisposeCalls);
+        Assert.True(fixture.Factory.Input!.IsDisposalComplete);
+
+        failure.RetryCleanup();
+
+        Assert.True(failure.IsCleanupComplete);
+        Assert.Equal(2, fixture.Factory.Backend.DisposeCalls);
+        Assert.Equal(1, fixture.Factory.Input.DisposeCalls);
+    }
+
+    [Fact]
+    public void BootstrapConstructionWithoutCleanupOwnerAbortsHostStartup()
+    {
+        var bootstrapFailure = (ImGuiBootstrapperConstructionException)
+            Activator.CreateInstance(
+                typeof(ImGuiBootstrapperConstructionException),
+                BindingFlags.Instance | BindingFlags.NonPublic,
+                binder: null,
+                args: [new InvalidOperationException("partial Silk construction")],
+                culture: null)!;
+        using var fixture = new Fixture(bootstrapFailure: bootstrapFailure);
+
+        Assert.Throws<ImGuiBootstrapperConstructionException>(fixture.Compose);
+
+        Assert.True(fixture.Factory.Input!.IsDisposalComplete);
+        Assert.Null(fixture.Publication.Owner);
+        Assert.DoesNotContain(
+            fixture.Logs,
+            message => message.Contains("devtools disabled", StringComparison.Ordinal));
+    }
+
+    [Fact]
+    public void GameWindowUsesProductionPhaseAndDoesNotRetainHostClosures()
+    {
+        string source = File.ReadAllText(Path.Combine(
+            FindRepoRoot(),
+            "src",
+            "AcDream.App",
+            "Rendering",
+            "GameWindow.cs"));
+
+        Assert.Contains("new SettingsDevToolsCompositionPhase(", source,
+            StringComparison.Ordinal);
+        Assert.DoesNotContain("new AcDream.UI.ImGui.ImGuiBootstrapper(", source,
+            StringComparison.Ordinal);
+        Assert.DoesNotContain("getPlayerPosition: () => GetDebugPlayerPosition()", source,
+            StringComparison.Ordinal);
+        Assert.DoesNotContain("_runtimeSettings.ApplyStartup(", source,
+            StringComparison.Ordinal);
+    }
+
+    private sealed class Fixture : IDisposable
+    {
+        private readonly SettingsDevToolsCompositionPoint? _failurePoint;
+        private readonly InputDispatcher _dispatcher;
+        private readonly FrameProfiler _profiler = new();
+
+        public Fixture(
+            bool enabled = true,
+            SettingsDevToolsCompositionPoint? failurePoint = null,
+            int backendDisposeFailures = 0,
+            bool inputSupported = true,
+            Exception? bootstrapFailure = null)
+        {
+            _failurePoint = failurePoint;
+            Factory = new Factory(
+                backendDisposeFailures,
+                inputSupported,
+                bootstrapFailure);
+            Publication = new Publication();
+            Startup = new StartupTarget();
+            Settings = new RuntimeSettingsController(
+                new Storage(),
+                QualitySettings.From,
+                static _ => { });
+            _dispatcher = InputDispatcher.CreateDetached(
+                new KeyboardSource(),
+                new MouseSource(),
+                new KeyBindings());
+            _dispatcher.Attach();
+            var camera = new CameraController(new OrbitCamera(), new FlyCamera());
+            Host = new HostInputCameraResult(
+                null!,
+                null!,
+                null,
+                null,
+                null,
+                _dispatcher,
+                camera,
+                null);
+            Platform = new GameWindowPlatformResult<GL, IInputContext>(null!, null!);
+            Content = (ContentEffectsAudioResult)RuntimeHelpers.GetUninitializedObject(
+                typeof(ContentEffectsAudioResult));
+            Dependencies = new SettingsDevToolsDependencies(
+                DispatchProxy.Create<IView, ViewProxy>(),
+                Settings,
+                Startup,
+                new HostQuiescenceGate(),
+                new ChatLog(),
+                new CombatState(),
+                new LocalPlayerState(new Spellbook()),
+                enabled
+                    ? new SettingsDevToolsOptionalDependencies(
+                        new Facts(),
+                        new KeyBindingTarget(),
+                        new DeferredCanonicalWorldEntityCountSource(),
+                        new DeferredRenderFrameDiagnosticsSource(),
+                        new DeferredDevToolsPlayerModeCommands())
+                    : null,
+                new RuntimeDiagnosticCommandSlot(),
+                new CombatFeedbackSlot(),
+                new KeyBindings(),
+                _profiler,
+                new FramebufferResizeController(new ViewportAspectState()),
+                Logs.Add);
+        }
+
+        public List<SettingsDevToolsCompositionPoint> Points { get; } = [];
+        public List<string> Logs { get; } = [];
+        public Factory Factory { get; }
+        public Publication Publication { get; }
+        public StartupTarget Startup { get; }
+        public RuntimeSettingsController Settings { get; }
+        public SettingsDevToolsDependencies Dependencies { get; }
+        public HostInputCameraResult Host { get; }
+        public GameWindowPlatformResult<GL, IInputContext> Platform { get; }
+        public ContentEffectsAudioResult Content { get; }
+
+        public SettingsDevToolsResult Compose() =>
+            new SettingsDevToolsCompositionPhase(
+                Dependencies,
+                Publication,
+                Factory,
+                point =>
+                {
+                    Points.Add(point);
+                    if (point == _failurePoint)
+                        throw new InvalidOperationException($"fault at {point}");
+                }).Compose(Platform, Host, Content);
+
+        public void Dispose()
+        {
+            Publication.Owner?.Dispose();
+            _dispatcher.Dispose();
+            _profiler.Dispose();
+        }
+    }
+
+    private sealed class Publication : IGameWindowSettingsDevToolsPublication
+    {
+        public DevToolsCompositionOwner? Owner { get; private set; }
+        public int PublishCalls { get; private set; }
+
+        public void PublishDevTools(DevToolsCompositionOwner value)
+        {
+            if (Owner is not null)
+                throw new InvalidOperationException("duplicate publication");
+            Owner = value;
+            PublishCalls++;
+        }
+    }
+
+    private sealed class Factory(
+        int backendDisposeFailures,
+        bool inputSupported,
+        Exception? bootstrapFailure)
+        : ISettingsDevToolsCompositionFactory
+    {
+        public int Calls { get; private set; }
+        public InputContext? Input { get; private set; }
+        public Bootstrap? Bootstrap { get; private set; }
+        public Backend? Backend { get; private set; }
+
+        public bool IsSupported(IInputContext input)
+        {
+            Calls++;
+            return inputSupported;
+        }
+
+        public IDevToolsInputContext CreateInputContext(
+            IInputContext input,
+            HostQuiescenceGate quiescence)
+        {
+            Calls++;
+            return Input = new InputContext();
+        }
+
+        public IImGuiBootstrapper CreateBootstrap(
+            GL gl,
+            IView window,
+            IInputContext input)
+        {
+            Calls++;
+            if (bootstrapFailure is not null)
+                throw bootstrapFailure;
+            return Bootstrap = new Bootstrap();
+        }
+
+        public ImGuiPanelHost CreatePanelHost()
+        {
+            Calls++;
+            return new ImGuiPanelHost();
+        }
+
+        public IDevToolsFrameBackend CreateBackend(
+            IImGuiBootstrapper bootstrap,
+            ImGuiPanelHost panels)
+        {
+            Calls++;
+            return Backend = new Backend(
+                (Bootstrap)bootstrap,
+                backendDisposeFailures);
+        }
+    }
+
+    private sealed class InputContext : IDevToolsInputContext
+    {
+        public bool Activated { get; private set; }
+        public int DisposeCalls { get; private set; }
+        public bool IsDisposalComplete { get; private set; }
+        public nint Handle => 0;
+        public IReadOnlyList<IGamepad> Gamepads { get; } = [];
+        public IReadOnlyList<IJoystick> Joysticks { get; } = [];
+        public IReadOnlyList<IKeyboard> Keyboards { get; } = [];
+        public IReadOnlyList<IMouse> Mice { get; } = [];
+        public IReadOnlyList<IInputDevice> OtherDevices { get; } = [];
+#pragma warning disable CS0067
+        public event Action<IInputDevice, bool>? ConnectionChanged;
+#pragma warning restore CS0067
+        public void Activate() => Activated = true;
+        public void Deactivate() => Activated = false;
+        public void Dispose()
+        {
+            DisposeCalls++;
+            Activated = false;
+            IsDisposalComplete = true;
+        }
+    }
+
+    private sealed class Bootstrap : IImGuiBootstrapper
+    {
+        public int DisposeCalls { get; private set; }
+        public void BeginFrame(float deltaSeconds) { }
+        public void Render() { }
+        public void AbortFrame() { }
+        public void Dispose() => DisposeCalls++;
+    }
+
+    private sealed class Backend(
+        Bootstrap bootstrap,
+        int remainingDisposeFailures) : IDevToolsFrameBackend
+    {
+        private int _remainingDisposeFailures = remainingDisposeFailures;
+        public int DisposeCalls { get; private set; }
+        public int LayoutCalls { get; private set; }
+        public void BeginFrame(float deltaSeconds) { }
+        public void AbortFrame() { }
+        public bool BeginMainMenuBar() => false;
+        public void EndMainMenuBar() { }
+        public bool BeginMenu(string label) => false;
+        public void EndMenu() { }
+        public bool MenuItem(string label, string? shortcut = null, bool selected = false) => false;
+        public void Separator() { }
+        public void RenderPanels(AcDream.UI.Abstractions.PanelContext context) { }
+        public void RenderDrawData() { }
+        public void SetWindowLayout(
+            string title,
+            Vector2 position,
+            Vector2 size,
+            DevToolsPanelLayoutCondition condition) => LayoutCalls++;
+        public void Dispose()
+        {
+            DisposeCalls++;
+            if (_remainingDisposeFailures-- > 0)
+                throw new InvalidOperationException("backend cleanup failed");
+            bootstrap.Dispose();
+        }
+    }
+
+    private sealed class StartupTarget : IRuntimeSettingsStartupTarget
+    {
+        public int DisplayCalls { get; private set; }
+        public int AudioCalls { get; private set; }
+        public void ApplyDisplay(DisplaySettings display) => DisplayCalls++;
+        public void ApplyAudio(AudioSettings audio) => AudioCalls++;
+    }
+
+    private sealed class Storage : IRuntimeSettingsStorage
+    {
+        public SettingsStore? LayoutStore => null;
+        public string Location => "memory://settings";
+        public DisplaySettings LoadDisplay() => DisplaySettings.Default;
+        public AudioSettings LoadAudio() => AudioSettings.Default;
+        public GameplaySettings LoadGameplay() => GameplaySettings.Default;
+        public ChatSettings LoadChat() => ChatSettings.Default;
+        public CharacterSettings LoadCharacter(string toonKey) => CharacterSettings.Default;
+        public void SaveDisplay(DisplaySettings display) { }
+        public void SaveAudio(AudioSettings audio) { }
+        public void SaveGameplay(GameplaySettings gameplay) { }
+        public void SaveChat(ChatSettings chat) { }
+        public void SaveCharacter(string toonKey, CharacterSettings character) { }
+    }
+
+    private sealed class KeyBindingTarget : IRuntimeKeyBindingTarget
+    {
+        public void Apply(KeyBindings bindings) { }
+    }
+
+    private sealed class Facts : IDevToolsRuntimeFacts
+    {
+        public Vector3 PlayerPosition => default;
+        public float PlayerHeadingDegrees => 0;
+        public uint PlayerCellId => 0;
+        public bool PlayerOnGround => false;
+        public bool InPlayerMode => false;
+        public bool InFlyMode => false;
+        public float VerticalVelocity => 0;
+        public int EntityCount => 0;
+        public int AnimatedCount => 0;
+        public int VisibleLandblocks => 0;
+        public int TotalLandblocks => 0;
+        public int ShadowObjectCount => 0;
+        public float NearestObjectDistance => float.PositiveInfinity;
+        public string NearestObjectLabel => "-";
+        public bool Colliding => false;
+        public bool CollisionWireframesVisible => false;
+        public int StreamingRadius => 0;
+        public float MouseSensitivity => 1;
+        public float ChaseDistance => 0;
+        public bool RmbOrbitHeld => false;
+        public string HourName => "0";
+        public float DayFraction => 0;
+        public string Weather => "Clear";
+        public int ActiveLights => 0;
+        public int RegisteredLights => 0;
+        public int ParticleCount => 0;
+        public float Fps => 60;
+        public float FrameMilliseconds => 16.7f;
+    }
+
+    private sealed class KeyboardSource : IKeyboardSource
+    {
+#pragma warning disable CS0067
+        public event Action<Key, ModifierMask>? KeyDown;
+        public event Action<Key, ModifierMask>? KeyUp;
+#pragma warning restore CS0067
+        public bool IsHeld(Key key) => false;
+        public ModifierMask CurrentModifiers => ModifierMask.None;
+    }
+
+    private sealed class MouseSource : IMouseSource
+    {
+#pragma warning disable CS0067
+        public event Action<MouseButton, ModifierMask>? MouseDown;
+        public event Action<MouseButton, ModifierMask>? MouseUp;
+        public event Action<float, float>? MouseMove;
+        public event Action<float>? Scroll;
+#pragma warning restore CS0067
+        public bool IsHeld(MouseButton button) => false;
+        public bool WantCaptureMouse => false;
+        public bool WantCaptureKeyboard => false;
+    }
+
+    public class ViewProxy : DispatchProxy
+    {
+        protected override object? Invoke(MethodInfo? targetMethod, object?[]? args)
+        {
+            if (targetMethod?.Name == "get_Size")
+                return new Vector2D<int>(1280, 720);
+            Type type = targetMethod?.ReturnType ?? typeof(void);
+            if (type == typeof(void))
+                return null;
+            return type.IsValueType ? Activator.CreateInstance(type) : null;
+        }
+    }
+
+    private static string FindRepoRoot()
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory is not null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "AcDream.slnx")))
+                return directory.FullName;
+            directory = directory.Parent;
+        }
+        throw new DirectoryNotFoundException("Could not find AcDream.slnx.");
+    }
+}

tests/AcDream.App.Tests/Rendering/DevToolsFramePresenterTests.cs

@@ -283,6 +283,7 @@ public sealed class DevToolsFramePresenterTests
 
     private sealed class RecordingBackend(List<string> calls) : IDevToolsFrameBackend
     {
+        public void Dispose() { }
         public HashSet<string> OpenMenus { get; } = [];
         public HashSet<string> ClickedItems { get; } = [];
         public List<(string Label, string? Shortcut, bool Selected)> MenuItems { get; } = [];

tests/AcDream.App.Tests/Rendering/DevToolsRuntimeSourcesTests.cs

@@ -0,0 +1,98 @@
+using AcDream.App.Rendering;
+using AcDream.App.Streaming;
+
+namespace AcDream.App.Tests.Rendering;
+
+public sealed class DevToolsRuntimeSourcesTests
+{
+    [Fact]
+    public void FrameDiagnosticsLateBindingPreservesSeedAndExpectedOwnerRelease()
+    {
+        var source = new DeferredRenderFrameDiagnosticsSource();
+        var first = new FrameSource(144, 6.9);
+        var other = new FrameSource(30, 33.3);
+
+        Assert.Equal(RenderFrameDiagnosticsSnapshot.Initial, source.Snapshot);
+        source.Bind(first);
+        Assert.Equal(144, source.Snapshot.Fps);
+        source.Unbind(other);
+        Assert.Equal(144, source.Snapshot.Fps);
+        source.Unbind(first);
+        Assert.Equal(RenderFrameDiagnosticsSnapshot.Initial, source.Snapshot);
+
+        source.Bind(other);
+        source.Deactivate();
+        Assert.Equal(RenderFrameDiagnosticsSnapshot.Initial, source.Snapshot);
+        Assert.Throws<ObjectDisposedException>(() => source.Bind(first));
+    }
+
+    [Fact]
+    public void FrameDiagnosticsRejectsACompetingCanonicalOwner()
+    {
+        var source = new DeferredRenderFrameDiagnosticsSource();
+        source.Bind(new FrameSource(60, 16.7));
+
+        Assert.Throws<InvalidOperationException>(() =>
+            source.Bind(new FrameSource(120, 8.3)));
+    }
+
+    [Fact]
+    public void PlayerModeCommandSlotUsesLiveTargetAndRejectsStaleRelease()
+    {
+        var source = new DeferredDevToolsPlayerModeCommands();
+        var first = new PlayerModeTarget();
+        var other = new PlayerModeTarget();
+
+        source.ToggleFlyOrChase();
+        source.Bind(first);
+        source.ToggleFlyOrChase();
+        source.Unbind(other);
+        source.ToggleFlyOrChase();
+        source.Unbind(first);
+        source.ToggleFlyOrChase();
+
+        Assert.Equal(2, first.ToggleCalls);
+        Assert.Equal(0, other.ToggleCalls);
+
+        source.Bind(other);
+        source.Deactivate();
+        source.ToggleFlyOrChase();
+        Assert.Equal(0, other.ToggleCalls);
+        Assert.Throws<ObjectDisposedException>(() => source.Bind(first));
+    }
+
+    [Fact]
+    public void WorldCountSlotCannotFreezeOrReleaseTheWrongWorld()
+    {
+        var source = new DeferredCanonicalWorldEntityCountSource();
+        var first = new GpuWorldState();
+        var other = new GpuWorldState();
+
+        source.Bind(first);
+        source.Unbind(other);
+        Assert.Throws<InvalidOperationException>(() => source.Bind(other));
+        source.Unbind(first);
+        source.Bind(other);
+        source.Deactivate();
+
+        Assert.Equal(0, source.EntityCount);
+        Assert.Throws<ObjectDisposedException>(() => source.Bind(first));
+    }
+
+    private sealed class FrameSource(double fps, double milliseconds)
+        : IRenderFrameDiagnosticsSnapshotSource
+    {
+        public RenderFrameDiagnosticsSnapshot Snapshot { get; } =
+            RenderFrameDiagnosticsSnapshot.Initial with
+            {
+                Fps = fps,
+                FrameMilliseconds = milliseconds,
+            };
+    }
+
+    private sealed class PlayerModeTarget : IDevToolsPlayerModeTarget
+    {
+        public int ToggleCalls { get; private set; }
+        public void ToggleFlyOrChase() => ToggleCalls++;
+    }
+}

tests/AcDream.App.Tests/Rendering/FramebufferResizeControllerTests.cs

@@ -57,6 +57,22 @@ public sealed class FramebufferResizeControllerTests
         Assert.Equal(["viewport:800x600", "camera:1.333", "devtools:800x600"], calls);
     }
 
+    [Fact]
+    public void DevToolsBindingReleasesExpectedTargetWithoutReplayingResize()
+    {
+        var calls = new List<string>();
+        var owner = new FramebufferResizeController(new ViewportAspectState());
+        var target = new DevTools(calls);
+        using var binding = new FramebufferDevToolsBinding(owner, target);
+
+        owner.Resize(900, 700);
+        binding.Dispose();
+        binding.Dispose();
+        owner.Resize(1000, 800);
+
+        Assert.Equal(["devtools:900x700"], calls);
+    }
+
     private sealed class Viewport(List<string> calls) : IFramebufferViewportTarget
     {
         public void ResizeViewport(int width, int height) =>

tests/AcDream.App.Tests/Rendering/GameWindowRenderLeafCompositionTests.cs

@@ -94,7 +94,13 @@ public sealed class GameWindowRenderLeafCompositionTests
             Assert.DoesNotContain(identifier, source, StringComparison.Ordinal);
 
         Assert.Contains("new AcDream.App.Rendering.PaperdollFramePresenter(", source);
-        Assert.Contains("new AcDream.App.Rendering.DevToolsFramePresenter(", source);
+        string settingsComposition = File.ReadAllText(Path.Combine(
+            FindRepoRoot(),
+            "src",
+            "AcDream.App",
+            "Composition",
+            "SettingsDevToolsComposition.cs"));
+        Assert.Contains("new DevToolsFramePresenter(", settingsComposition);
         Assert.Contains("new AcDream.App.Rendering.RenderFrameResourceController(", source);
         Assert.Contains("new AcDream.App.Rendering.RenderWeatherFrameController(", source);
         Assert.Contains("new AcDream.App.Rendering.PrivatePresentationRenderer(", source);
@@ -119,7 +125,7 @@ public sealed class GameWindowRenderLeafCompositionTests
             "new ResourceShutdownStage(\"submitted GPU work\"",
             "new ResourceShutdownStage(\"render frontends\"",
             "new(\"developer tools\"",
-            "_devToolsBackend?.Dispose()",
+            "owner.DisposeFrontend()",
             "new(\"portal tunnel\"",
             "new(\"paperdoll viewport\"",
             "new ResourceShutdownStage(\"OpenGL context\"");
@@ -135,7 +141,7 @@ public sealed class GameWindowRenderLeafCompositionTests
         AssertAppearsInOrder(
             source,
             "_frameGraphs.Withdraw();",
-            "_devToolsBackend?.Dispose()",
+            "owner.DisposeFrontend()",
             "new ResourceShutdownStage(\"input\"",
             "_input?.Dispose();",
             "new ResourceShutdownStage(\"OpenGL context\"");

tests/AcDream.App.Tests/Rendering/GameWindowSlice8BoundaryTests.cs

@@ -56,8 +56,8 @@ public sealed class GameWindowSlice8BoundaryTests
             "this).Compose(platform);",
             "new ContentEffectsAudioCompositionPhase(",
             "this).Compose(platform, hostInputCamera);",
-            "_runtimeSettings.ApplyStartup(",
+            "new SettingsDevToolsCompositionPhase(",
-            "new RuntimeSettingsStartupTargets(",
+            "this).Compose(platform, hostInputCamera, contentEffectsAudio);",
             "_uiHost = _retailUiLease.AcquireHost(",
             "_uiHost.WireMouse(m)",
             "_uiHost.WireKeyboard(kb)",
@@ -138,10 +138,19 @@ public sealed class GameWindowSlice8BoundaryTests
 
         Assert.DoesNotContain("private void CycleTimeOfDay()", source, StringComparison.Ordinal);
         Assert.DoesNotContain("private void CycleWeather()", source, StringComparison.Ordinal);
+        string settingsPhase = File.ReadAllText(Path.Combine(
+            FindRepoRoot(),
+            "src",
+            "AcDream.App",
+            "Composition",
+            "SettingsDevToolsComposition.cs"));
+        AssertAppearsInOrder(
+            settingsPhase,
+            "debugVm.CycleTimeOfDay = _dependencies.DiagnosticCommands.CycleTimeOfDay;",
+            "debugVm.CycleWeather = _dependencies.DiagnosticCommands.CycleWeather;",
+            "debugVm.ToggleCollisionWires =");
         AssertAppearsInOrder(
             load,
-            "_debugVm.CycleTimeOfDay =",
-            "_runtimeDiagnosticCommands.CycleTimeOfDay;",
             "new AcDream.App.Diagnostics.RuntimeDiagnosticCommandController(",
             "_runtimeDiagnosticCommands.Bind(runtimeDiagnostics);");
     }
@@ -267,11 +276,21 @@ public sealed class GameWindowSlice8BoundaryTests
             "Window.Create(options)");
         AssertAppearsInOrder(
             load,
-            "_runtimeSettings.ApplyStartup(",
+            "new SettingsDevToolsCompositionPhase(",
-            "if (DevToolsEnabled)",
+            "this).Compose(platform, hostInputCamera, contentEffectsAudio);",
             "TerrainAtlas.Build(",
             "_runtimeSettings.BindRuntimeTargets(",
             "_liveSessionHost.Start(_options)");
+        string settingsPhase = File.ReadAllText(Path.Combine(
+            FindRepoRoot(),
+            "src",
+            "AcDream.App",
+            "Composition",
+            "SettingsDevToolsComposition.cs"));
+        AssertAppearsInOrder(
+            settingsPhase,
+            "_dependencies.Settings.ApplyStartup(_dependencies.StartupTarget);",
+            "_dependencies.DevTools is { } optional");
         AssertAppearsInOrder(
             shutdown,
             "_runtimeSettings.UnbindViewModel()",

tests/AcDream.App.Tests/Settings/RuntimeSettingsControllerTests.cs

@@ -81,6 +81,31 @@ public sealed class RuntimeSettingsControllerTests
             controller.BindRuntimeTargets(new FakeRuntimeTargets(events)));
     }
 
+    [Fact]
+    public void ViewModelBindingReleasesOnlyItsExpectedInstance()
+    {
+        var controller = CreateController();
+        using InputDispatcher dispatcher = CreateDispatcher();
+        RuntimeSettingsViewModelBinding first = controller.CreateViewModelBinding(
+            new KeyBindings(),
+            dispatcher,
+            static _ => { });
+
+        first.Dispose();
+        RuntimeSettingsViewModelBinding second = controller.CreateViewModelBinding(
+            new KeyBindings(),
+            dispatcher,
+            static _ => { });
+        first.Dispose();
+
+        Assert.Throws<InvalidOperationException>(() =>
+            controller.CreateViewModelBinding(
+                new KeyBindings(),
+                dispatcher,
+                static _ => { }));
+        second.Dispose();
+    }
+
     [Fact]
     public void StartupRetryResumesAfterLastSuccessfulStage()
     {

tests/AcDream.UI.Abstractions.Tests/Panels/Chat/ChatVMLastTellSenderTests.cs

@@ -12,6 +12,20 @@ namespace AcDream.UI.Abstractions.Tests.Panels.Chat;
 /// </summary>
 public sealed class ChatVMLastTellSenderTests
 {
+    [Fact]
+    public void DisposeDetachesTranscriptSubscriptionExactlyOnce()
+    {
+        var log = new ChatLog();
+        var vm = new ChatVM(log);
+        log.OnTellReceived("Before", "ping", 0x5000_0001u);
+
+        vm.Dispose();
+        vm.Dispose();
+        log.OnTellReceived("After", "pong", 0x5000_0002u);
+
+        Assert.Equal("Before", vm.LastIncomingTellSender);
+    }
+
     [Fact]
     public void LastIncomingTellSender_StartsNull()
     {

tests/AcDream.UI.Abstractions.Tests/Panels/Debug/DebugVMTests.cs

@@ -14,6 +14,22 @@ namespace AcDream.UI.Abstractions.Tests.Panels.Debug;
 /// </summary>
 public sealed class DebugVMTests
 {
+    [Fact]
+    public void DisposeDetachesEveryCombatSubscriptionExactlyOnce()
+    {
+        var combat = new CombatState();
+        DebugVM vm = NewVm(combat);
+        combat.OnKillerNotification("first", 1);
+        Assert.Single(vm.CombatEvents);
+
+        vm.Dispose();
+        vm.Dispose();
+        combat.OnKillerNotification("second", 2);
+        combat.OnAttackDone(3, 4);
+
+        Assert.Single(vm.CombatEvents);
+    }
+
     /// <summary>
     /// Build a minimal <see cref="DebugVM"/> with safe defaults for every
     /// constructor source. Tests that don't care about a particular source