Make character UI retries transactional

tests/AcDream.App.Tests/UI/Layout/CharacterManagementUiControllerTests.cs

@@ -188,6 +188,66 @@ public sealed class CharacterManagementUiControllerTests
         Assert.Equal(3, resourceAttempts);
     }
 
+    [Fact]
+    public void MountCoordinator_PostAttachFailuresDisposeBeforeRetryAndRecovery()
+    {
+        var host = new UiRoot { Width = 800f, Height = 600f };
+        var runtime = new FakeRuntime();
+        using var dialogs = new RetailDialogFactory(
+            host,
+            RetailDialogFactoryTests.BuildDialogLayout);
+        var screens = new List<ImportedLayout>();
+        int failingAttempts = 2;
+        using var coordinator = new CharacterManagementUiMountCoordinator(
+            host,
+            runtime.Bindings,
+            () => dialogs,
+            () =>
+            {
+                ImportedLayout screen = BuildScreen();
+                screens.Add(screen);
+                bool throwAfterAttach = failingAttempts-- > 0;
+                return new CharacterManagementUiMountResources(
+                    0x21000004u,
+                    screen,
+                    (_, _) => throwAfterAttach
+                        ? throw new InvalidOperationException(
+                            "template failed after root attach")
+                        : BuildRow(),
+                    TestStrings());
+            });
+
+        coordinator.Tick();
+        Assert.Null(coordinator.Controller);
+        Assert.Empty(host.Children);
+        Assert.Single(screens);
+        AssertDetachedAndUnbound(screens[0]);
+
+        coordinator.Tick();
+        Assert.Null(coordinator.Controller);
+        Assert.Empty(host.Children);
+        Assert.Equal(2, screens.Count);
+        Assert.All(screens, AssertDetachedAndUnbound);
+
+        coordinator.Tick();
+        CharacterManagementUiController mounted = Assert.IsType<
+            CharacterManagementUiController>(coordinator.Controller);
+        Assert.Equal(3, screens.Count);
+        Assert.Single(host.Children);
+        Assert.Same(mounted.Root, host.Children[0]);
+        Assert.NotNull(Assert.IsType<UiButton>(screens[2].FindElement(
+            CharacterManagementUiController.EnterElementId)).OnClick);
+
+        coordinator.Tick();
+        Assert.Equal(3, screens.Count);
+        Assert.Single(host.Children);
+
+        coordinator.Dispose();
+        Assert.Empty(host.Children);
+        Assert.Null(coordinator.Controller);
+        Assert.All(screens, AssertDetachedAndUnbound);
+    }
+
     [Fact]
     public void DeleteConfirmation_IsCaseInsensitive_ThenWaitsThroughAckUntilFreshRoster()
     {
@@ -509,6 +569,17 @@ public sealed class CharacterManagementUiControllerTests
             "Please Wait",
             "Entering World");
 
+    private static void AssertDetachedAndUnbound(ImportedLayout screen)
+    {
+        Assert.Null(screen.Root.Parent);
+        Assert.Null(Assert.IsType<UiButton>(screen.FindElement(
+            CharacterManagementUiController.EnterElementId)).OnClick);
+        Assert.Null(Assert.IsType<UiButton>(screen.FindElement(
+            CharacterManagementUiController.DeleteElementId)).OnClick);
+        Assert.Null(Assert.IsType<UiButton>(screen.FindElement(
+            CharacterManagementUiController.RestoreElementId)).OnClick);
+    }
+
     private static ImportedLayout BuildScreen(bool includePreview = false)
     {
         var root = new ElementInfo