Prune stale FunctionalUI render cache paths

Prevent keyed chat timeline generations from leaving old renderer controls, components, and content flyouts cached after they disappear from the rendered tree. This keeps the #917 row-identity fix from trading stale visual reuse for unbounded detached UI cache growth.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: shanselman

src/OpenClawTray.FunctionalUI/FunctionalUI.cs

@@ -913,10 +913,19 @@ internal sealed class UiRenderer(Action requestRender)
     private readonly Dictionary<string, Component> _components = new();
     private readonly Dictionary<string, Flyout> _contentFlyouts = new();
     private readonly HashSet<string> _mountedPaths = new();
+    private readonly HashSet<string> _visitedControlPaths = new();
+    private readonly HashSet<string> _visitedComponentKeys = new();
+    private readonly HashSet<string> _visitedContentFlyoutPaths = new();
 
     public UIElement Render(Element element, string path, List<Action> effects)
     {
-        return RenderElement(element, path, effects);
+        _visitedControlPaths.Clear();
+        _visitedComponentKeys.Clear();
+        _visitedContentFlyoutPaths.Clear();
+
+        var rendered = RenderElement(element, path, effects);
+        PruneUnvisitedPaths();
+        return rendered;
     }
 
     public void Dispose()
@@ -993,6 +1002,8 @@ private UIElement RenderNavigationHost(INavigationHostElement element, string pa
 
     private T GetOrCreate<T>(string path) where T : UIElement, new()
     {
+        _visitedControlPaths.Add(path);
+
         if (_controls.TryGetValue(path, out var existing) && existing is T typed)
             return typed;
 
@@ -1020,6 +1031,8 @@ private UIElement RenderComponent(ComponentElement element, string path, List<Ac
     {
         var componentKey = GetComponentKey(element.ComponentType);
         var key = path + ":" + componentKey;
+        _visitedComponentKeys.Add(key);
+
         if (!_components.TryGetValue(key, out var component))
         {
             component = (Component)Activator.CreateInstance(element.ComponentType)!;
@@ -1378,6 +1391,8 @@ private FlyoutBase CreateFlyout(FlyoutElement element, string path, List<Action>
 
     private Flyout CreateContentFlyout(ContentFlyoutElement element, string path, List<Action> effects)
     {
+        _visitedContentFlyoutPaths.Add(path);
+
         // Cache the Flyout instance per path so its identity is STABLE across
         // re-renders. ConfigureButton reassigns control.Flyout on every render,
         // and a full-root re-render fires on every state change (including the
@@ -1403,6 +1418,39 @@ private Flyout CreateContentFlyout(ContentFlyoutElement element, string path, Li
         return flyout;
     }
 
+    private void PruneUnvisitedPaths()
+    {
+        foreach (var (key, component) in _components.ToArray())
+        {
+            if (_visitedComponentKeys.Contains(key))
+                continue;
+
+            component.Context.RunEffectCleanups();
+            _components.Remove(key);
+        }
+
+        foreach (var (path, flyout) in _contentFlyouts.ToArray())
+        {
+            if (_visitedContentFlyoutPaths.Contains(path))
+                continue;
+
+            flyout.Hide();
+            flyout.Content = null;
+            _contentFlyouts.Remove(path);
+        }
+
+        foreach (var (path, control) in _controls.ToArray())
+        {
+            if (_visitedControlPaths.Contains(path))
+                continue;
+
+            _mountedPaths.Remove(path);
+            DetachChildren(control);
+            RemoveFromParent(control);
+            _controls.Remove(path);
+        }
+    }
+
     private static MenuFlyout CreateMenuFlyout(MenuFlyoutContentElement element)
     {
         var flyout = new MenuFlyout { Placement = element.Placement };

tests/OpenClaw.Tray.Tests/FunctionalUiModifierResetContractTests.cs

@@ -32,6 +32,23 @@ public void ApplyModifiers_ClearsStaleBorderTextAndControlValues()
         Assert.Contains("c.ClearValue(Control.BorderBrushProperty);", functionalUi);
     }
 
+    [Fact]
+    public void UiRenderer_PrunesUnvisitedCachesAfterRender()
+    {
+        var functionalUi = Read("src", "OpenClawTray.FunctionalUI", "FunctionalUI.cs");
+
+        Assert.Contains("private readonly HashSet<string> _visitedControlPaths = new();", functionalUi);
+        Assert.Contains("private readonly HashSet<string> _visitedComponentKeys = new();", functionalUi);
+        Assert.Contains("private readonly HashSet<string> _visitedContentFlyoutPaths = new();", functionalUi);
+        Assert.Contains("PruneUnvisitedPaths();", functionalUi);
+        Assert.Contains("component.Context.RunEffectCleanups();", functionalUi);
+        Assert.Contains("flyout.Hide();", functionalUi);
+        Assert.Contains("flyout.Content = null;", functionalUi);
+        Assert.Contains("_mountedPaths.Remove(path);", functionalUi);
+        Assert.Contains("DetachChildren(control);", functionalUi);
+        Assert.Contains("_controls.Remove(path);", functionalUi);
+    }
+
     private static string Read(params string[] parts)
         => File.ReadAllText(Path.Combine(new[] { TestRepositoryPaths.GetRepositoryRoot() }.Concat(parts).ToArray()));
 }