fix: prevent sidebar toggle icon clipping at display scales

docs/CONNECTION_ARCHITECTURE.md

@@ -193,6 +193,9 @@ A floating-style subtle reopen button reserves a dedicated 56 DIP row at
 the content's top-left below the titlebar, never covering hosted hit targets.
 The pane toggle retains a 40 DIP target and 16 DIP glyph in both states; focus
 moves to the surviving toggle. Pane changes do not remount chat or reset drafts.
+Both Workspace toggle states and the Settings toggle use the native
+`SubtleButtonStyle` with zero padding for icon-only content. The style's default
+text-button padding must not squeeze the glyph inside the fixed 40 DIP target.
 The companion uses a native TitleBar titled OpenClaw Settings with shared claw
 artwork. Search, Back, and Forward live beside the toggle in its stable sidebar
 toolbar. The native pane reserves 56 DIP above its items, including in compact mode.

src/OpenClaw.Tray.WinUI/Windows/HubWindow.xaml

@@ -182,7 +182,7 @@
                 AutomationProperties.AutomationId="SettingsTogglePane"
                 AutomationProperties.Name="Toggle navigation pane"
                 ToolTipService.ToolTip="Toggle navigation pane"
-                Width="40" Height="40" Margin="4,0,0,0"
+                Width="40" Height="40" Padding="0" Margin="4,0,0,0"
                 HorizontalAlignment="Left" VerticalAlignment="Top"
                 Style="{StaticResource SubtleButtonStyle}" Click="OnNavPaneToggleButtonClick">
             <FontIcon Glyph="&#xE90C;" FontSize="16"/>

src/OpenClaw.Tray.WinUI/Windows/WorkspaceWindow.xaml

@@ -200,13 +200,13 @@
         <Button x:Name="CollapsePaneButton" x:Uid="WorkspaceShell_TogglePane" Click="OnTogglePane"
                 AutomationProperties.AutomationId="WorkspaceTogglePane"
                 HorizontalAlignment="Left" VerticalAlignment="Top" Margin="4,8,0,0"
-                Width="40" Height="40" Style="{StaticResource SubtleButtonStyle}">
+                Width="40" Height="40" Padding="0" Style="{StaticResource SubtleButtonStyle}">
             <FontIcon Glyph="&#xE90C;" FontSize="16"/>
         </Button>
         <Button x:Name="ReopenPaneButton" x:Uid="WorkspaceShell_TogglePane" Click="OnTogglePane"
                 AutomationProperties.AutomationId="WorkspaceReopenPane"
                 Visibility="Collapsed" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="4,8,0,0"
-                Width="40" Height="40" Style="{StaticResource SubtleButtonStyle}">
+                Width="40" Height="40" Padding="0" Style="{StaticResource SubtleButtonStyle}">
             <FontIcon Glyph="&#xE90C;" FontSize="16"/>
         </Button>
         </Grid>

tests/OpenClaw.Tray.Tests/Presentation/WorkspaceNavigationTests.cs

@@ -473,6 +473,7 @@ public void PaneToggle_TargetAndGlyphSizesMatchAcrossPaneStates()
             Assert.Equal("{StaticResource SubtleButtonStyle}", (string?)toggle.Attribute("Style"));
             Assert.Equal("40", (string?)toggle.Attribute("Width"));
             Assert.Equal("40", (string?)toggle.Attribute("Height"));
+            Assert.Equal("0", (string?)toggle.Attribute("Padding"));
             var icon = Assert.Single(toggle.Descendants(), element => element.Name.LocalName == "FontIcon");
             Assert.Equal("16", (string?)icon.Attribute("FontSize"));
         }

tests/OpenClaw.Tray.UITests/WorkspaceSessionLayoutTests.cs

@@ -1,5 +1,7 @@
+using System.Xml.Linq;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Markup;
 using OpenClawTray.Presentation;
 using OpenClawTray.Windows;
 using Windows.Foundation;
@@ -9,6 +11,71 @@ namespace OpenClaw.Tray.UITests;
 [Collection(UICollection.Name)]
 public sealed class WorkspaceSessionLayoutTests(UIThreadFixture ui)
 {
+    [Theory]
+    [InlineData("WorkspaceWindow.xaml", "CollapsePaneButton")]
+    [InlineData("WorkspaceWindow.xaml", "ReopenPaneButton")]
+    [InlineData("HubWindow.xaml", "NavPaneToggleButton")]
+    public async Task PaneToggle_LeavesRoundingRoomAroundUnconstrainedGlyph(string file, string name)
+    {
+        var root = Environment.GetEnvironmentVariable("OPENCLAW_REPO_ROOT")
+            ?? throw new InvalidOperationException("OPENCLAW_REPO_ROOT is required for production markup proof.");
+        var document = XDocument.Load(Path.Combine(root, "src", "OpenClaw.Tray.WinUI", "Windows", file));
+        XNamespace x = "http://schemas.microsoft.com/winfx/2006/xaml";
+        var markup = new XElement(document.Descendants().Single(element => (string?)element.Attribute(x + "Name") == name));
+        // Mount the production control without its window event handler or localized tooltip.
+        markup.Attribute("Click")!.Remove();
+        markup.Attribute(x + "Uid")!.Remove();
+        markup.SetAttributeValue("Visibility", "Visible");
+        markup.SetAttributeValue(XNamespace.Xmlns + "x", x.NamespaceName);
+
+        await ui.RunOnUIAsync(async () =>
+        {
+            var button = Assert.IsType<Button>(XamlReader.Load(markup.ToString()));
+            var icon = Assert.IsType<FontIcon>(button.Content);
+            var reference = new FontIcon
+            {
+                Glyph = icon.Glyph,
+                FontFamily = icon.FontFamily,
+                FontSize = icon.FontSize,
+                IsTextScaleFactorEnabled = icon.IsTextScaleFactorEnabled
+            };
+            ui.Container.Children.Add(button);
+            ui.Container.Children.Add(reference);
+            try
+            {
+                await ui.YieldToRenderAsync();
+                foreach (var theme in new[] { ElementTheme.Light, ElementTheme.Dark })
+                {
+                    button.RequestedTheme = theme;
+                    button.UpdateLayout();
+                    reference.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
+                    var size = reference.DesiredSize;
+                    Assert.True(size.Width > 0 && size.Height > 0);
+                    Assert.InRange(button.ActualWidth, 39, 41);
+                    Assert.InRange(button.ActualHeight, 39, 41);
+                    var contentWidth = button.ActualWidth - button.Padding.Left - button.Padding.Right
+                        - button.BorderThickness.Left - button.BorderThickness.Right;
+                    // Leave a physical pixel on each side for fractional-DPI layout rounding.
+                    var roundingRoom = 2 / button.XamlRoot.RasterizationScale;
+                    Assert.True(contentWidth >= size.Width + roundingRoom,
+                        $"Glyph width {size.Width} has no rounding room in content width {contentWidth} at raster scale {button.XamlRoot.RasterizationScale}.");
+                    Assert.True(icon.ActualWidth >= size.Width,
+                        $"Glyph width {size.Width} was clipped to {icon.ActualWidth} at raster scale {button.XamlRoot.RasterizationScale}.");
+                    Assert.True(icon.ActualHeight >= size.Height,
+                        $"Glyph height {size.Height} was clipped to {icon.ActualHeight}.");
+                    var bounds = icon.TransformToVisual(button).TransformBounds(new Rect(0, 0, size.Width, size.Height));
+                    Assert.True(bounds.Left >= 0 && bounds.Top >= 0 &&
+                        bounds.Right <= button.ActualWidth && bounds.Bottom <= button.ActualHeight);
+                }
+            }
+            finally
+            {
+                ui.Container.Children.Remove(button);
+                ui.Container.Children.Remove(reference);
+            }
+        });
+    }
+
     [Theory]
     [InlineData(false, false)]
     [InlineData(false, true)]