diff --git a/MainWindow.xaml b/MainWindow.xaml
index 4c25257..b847181 100644
--- a/MainWindow.xaml
+++ b/MainWindow.xaml
@@ -45,24 +45,10 @@
             </DrawingImage.Drawing>
         </DrawingImage>
 
-        <!-- Eye icon: open when visible, slashed when hidden (source rows) -->
-        <Style x:Key="EyeIconStyle" TargetType="Path">
-            <Setter Property="Data" Value="M12,4.5C7,4.5 2.73,7.61 1,12c1.73,4.39 6,7.5 11,7.5s9.27,-3.11 11,-7.5c-1.73,-4.39 -6,-7.5 -11,-7.5zM12,17c-2.76,0 -5,-2.24 -5,-5s2.24,-5 5,-5 5,2.24 5,5 -2.24,5 -5,5zM12,9c-1.66,0 -3,1.34 -3,3s1.34,3 3,3 3,-1.34 3,-3 -1.34,-3 -3,-3z"/>
-            <Style.Triggers>
-                <DataTrigger Binding="{Binding IsVisible}" Value="False">
-                    <Setter Property="Data" Value="M12,7c2.76,0 5,2.24 5,5 0,0.65 -0.13,1.26 -0.36,1.83l2.92,2.92c1.51,-1.26 2.7,-2.89 3.43,-4.75 -1.73,-4.39 -6,-7.5 -11,-7.5 -1.4,0 -2.74,0.25 -3.98,0.7l2.16,2.16C10.74,7.13 11.35,7 12,7zM2,4.27l2.28,2.28 0.46,0.46C3.08,8.3 1.78,10.02 1,12c1.73,4.39 6,7.5 11,7.5 1.55,0 3.03,-0.3 4.38,-0.84l0.42,0.42L19.73,22 21,20.73 3.27,3 2,4.27zM7.53,9.8l1.55,1.55c-0.05,0.21 -0.08,0.43 -0.08,0.65 0,1.66 1.34,3 3,3 0.22,0 0.44,-0.03 0.65,-0.08l1.55,1.55c-0.67,0.33 -1.41,0.53 -2.2,0.53 -2.76,0 -5,-2.24 -5,-5 0,-0.79 0.2,-1.53 0.53,-2.2zM11.84,9.02l3.15,3.15 0.02,-0.16c0,-1.66 -1.34,-3 -3,-3l-0.17,0.01z"/>
-                </DataTrigger>
-            </Style.Triggers>
-        </Style>
-
-        <Style x:Key="EyeButton" TargetType="Button" BasedOn="{StaticResource IconButton}">
-            <Setter Property="ToolTip" Value="Hide Layer"/>
-            <Style.Triggers>
-                <DataTrigger Binding="{Binding IsVisible}" Value="False">
-                    <Setter Property="ToolTip" Value="Show Layer"/>
-                </DataTrigger>
-            </Style.Triggers>
-        </Style>
+        <!-- EyeButton/EyeIconStyle MOVED to Themes/Controls.xaml (2026-09-01): Controls/
+             LeftPanel.xaml consumes them via StaticResource, and window-scope resources
+             are invisible to a UserControl at parse time — the "known test failure" that
+             was actually an app-crash regression from the LeftPanel extraction. -->
         </ResourceDictionary>
     </Window.Resources>
 
diff --git a/MyMistakes.md b/MyMistakes.md
index 0d6a81c..5c11844 100644
--- a/MyMistakes.md
+++ b/MyMistakes.md
@@ -89,3 +89,38 @@ paths to `\\wsl.localhost\Debian\…` and throws "not a valid application for th
 OS" when handed a Linux ELF ffmpeg. So never plan to have dotnet exec a Linux
 ffmpeg here; verify the contract with shell/python instead, and leave the
 CLR→real-ffmpeg run to the native Windows suite.
+
+## WPF hit-test truth in tests: `UIElement.InputHitTest`, NOT `VisualTreeHelper.HitTest`
+
+(2026-09-01, the RoundClip "known failure" post-mortem — a failure the map carried as
+"not a regression" for weeks without ever recording WHY.)
+
+**The trap:** `VisualTreeHelper.HitTest(window, pt)` returned the window's
+`WebViewHostPanel` overlay (`IsHitTestVisible="False"`, `Opacity=0`, ZERO children) for
+EVERY point in the window — so a "corner is grabbable" assertion could never pass, and
+it looked like a real interaction bug. The actual input pipeline (`UIElement.InputHitTest`,
+what Mouse routing uses) correctly returned the element's Grid at elem-center/corner-in/
+corner-exact and fell through to CanvasGrid just past the corner. The product was fine;
+the TEST was probing an API that doesn't model input semantics.
+
+**Rule:** any test asserting "where does a click land" uses `window.InputHitTest(pt)` +
+`IsDescendantOf` — never `VisualTreeHelper.HitTest`.
+
+**Diagnosis recipe (how the lie was caught in ~3 probe cycles, no guessing):** add a TEMP
+probe `[Fact]` in the RealApp collection that hit-tests a spread of points
+(elem-center / corner-in / corner-exact / corner-out / bg-center) and `Assert.Fail`s with a
+composed dump: per-point VTH hit + `InputHitTest` hit + ancestor chain (`GetParent` walk
+with `#Name`) + panel properties (`IsHitTestVisible/Opacity/children/actual size`) +
+`TranslatePoint` origins. Run the class alone, read the message, delete the probe.
+
+**Two sibling facts learned the same session (record-once):**
+1. A UserControl owns its own XAML namescope — after extracting a region out of a window,
+   `window.FindName("InnerPart")` returns null; resolve the UserControl by its window-level
+   name, then `pane.FindName("InnerPart")`. And window-scope STYLES are invisible to a
+   UserControl's `StaticResource` at parse time — move such styles to `Themes/Controls.xaml`
+   (the app-scope rule exists for this).
+2. Per-class `dotnet.exe vstest` from WSL DOES execute the RealApp/`MainWindow` tests fine
+   (they passed natively 2026-09-01) — only the FULL suite hangs (WASAPI startup). And the
+   test process shares `%APPDATA%\ytLlive\startup.log` with the real app: lines like
+   `camera 'test-camera' failed` are test noise, not DB state — to check pollution, query
+   the DB directly (`python3 sqlite3`, `SELECT DeviceId FROM Webcam`), not the log.
diff --git a/TASKS.md b/TASKS.md
index a2d8537..9ab2605 100644
--- a/TASKS.md
+++ b/TASKS.md
@@ -1311,8 +1311,16 @@ What landed — core optimization + SceneGraph component, all in one commit:
 
 **Verification:** SceneCompositorTests 4, StretchMathTests 4, BackgroundTests 16, SceneCatalogTests 18,
 LayoutStorePersistenceTests 12, FramePumpTests 9, SceneGraphTests 1 all green. RealAppHost GUI/collection
-tests (SourceNaming, RoundClip, BackgroundHeal, ...) construct a real `MainWindow` and cannot run in a
-headless WSL session (pre-existing limitation, not caused by this change).
+tests (SourceNaming, RoundClip, BackgroundHeal, ...) construct a real `MainWindow` — **CORRECTED
+2026-09-01:** they DO run from WSL when invoked per-class through the Windows `dotnet.exe` vstest host
+(the old "cannot run headless" claim conflated them with the full-suite WASAPI hang). Two first-launch
+crashes this refactor shipped with were caught on the first real native launch and fixed same day:
+ctor-order `SceneGraph` NRE (`null!` field assigned after first ctor use — now field-initialized) and
+window-scope `EyeButton`/`EyeIconStyle` consumed via `StaticResource` from the extracted `LeftPanel`
+(UserControl namescopes can't see window resources — styles moved to `Themes/Controls.xaml`, the
+app-scope rule honored). The RoundClip "known failure" was then root-caused to stale test code
+(`window.FindName` across namescopes + `VisualTreeHelper.HitTest` where `UIElement.InputHitTest`
+models input) — test green 2026-09-01, the sole remaining known failure is the audio one.
 
 ### Design
 
diff --git a/Themes/Controls.xaml b/Themes/Controls.xaml
index 6db611c..6f35c14 100644
--- a/Themes/Controls.xaml
+++ b/Themes/Controls.xaml
@@ -66,6 +66,29 @@
         </Style.Triggers>
     </Style>
 
+    <!-- Eye icon: open when visible, slashed when hidden (source rows). App scope for
+         the same LeftPanel reason as EyeButton below. -->
+    <Style x:Key="EyeIconStyle" TargetType="Path">
+        <Setter Property="Data" Value="M12,4.5C7,4.5 2.73,7.61 1,12c1.73,4.39 6,7.5 11,7.5s9.27,-3.11 11,-7.5c-1.73,-4.39 -6,-7.5 -11,-7.5zM12,17c-2.76,0 -5,-2.24 -5,-5s2.24,-5 5,-5 5,2.24 5,5 -2.24,5 -5,5zM12,9c-1.66,0 -3,1.34 -3,3s1.34,3 3,3 3,-1.34 3,-3 -1.34,-3 -3,-3z"/>
+        <Style.Triggers>
+            <DataTrigger Binding="{Binding IsVisible}" Value="False">
+                <Setter Property="Data" Value="M12,7c2.76,0 5,2.24 5,5 0,0.65 -0.13,1.26 -0.36,1.83l2.92,2.92c1.51,-1.26 2.7,-2.89 3.43,-4.75 -1.73,-4.39 -6,-7.5 -11,-7.5 -1.4,0 -2.74,0.25 -3.98,0.7l2.16,2.16C10.74,7.13 11.35,7 12,7zM2,4.27l2.28,2.28 0.46,0.46C3.08,8.3 1.78,10.02 1,12c1.73,4.39 6,7.5 11,7.5 1.55,0 3.03,-0.3 4.38,-0.84l0.42,0.42L19.73,22 21,20.73 3.27,3 2,4.27zM7.53,9.8l1.55,1.55c-0.05,0.21 -0.08,0.43 -0.08,0.65 0,1.66 1.34,3 3,3 0.22,0 0.44,-0.03 0.65,-0.08l1.55,1.55c-0.67,0.33 -1.41,0.53 -2.2,0.53 -2.76,0 -5,-2.24 -5,-5 0,-0.79 0.2,-1.53 0.53,-2.2zM11.84,9.02l3.15,3.15 0.02,-0.16c0,-1.66 -1.34,-3 -3,-3l-0.17,0.01z"/>
+            </DataTrigger>
+        </Style.Triggers>
+    </Style>
+
+    <!-- Lives here (app scope), NOT in a window: Controls/LeftPanel.xaml references it
+         via StaticResource, and a UserControl cannot see window resources at parse
+         time (startup crash caught 2026-09-01). -->
+    <Style x:Key="EyeButton" TargetType="Button" BasedOn="{StaticResource IconButton}">
+        <Setter Property="ToolTip" Value="Hide Layer"/>
+        <Style.Triggers>
+            <DataTrigger Binding="{Binding IsVisible}" Value="False">
+                <Setter Property="ToolTip" Value="Show Layer"/>
+            </DataTrigger>
+        </Style.Triggers>
+    </Style>
+
     <Style x:Key="YtTextBox" TargetType="TextBox">
         <Setter Property="Background" Value="#0f3460"/>
         <Setter Property="Foreground" Value="#e0e0e0"/>
diff --git a/ViewModels/MainViewModel.cs b/ViewModels/MainViewModel.cs
index 4a3af03..f1ed14f 100644
--- a/ViewModels/MainViewModel.cs
+++ b/ViewModels/MainViewModel.cs
@@ -41,7 +41,11 @@ public partial class MainViewModel : ViewModelBase
     // Scene graph (TASK 31): owns the scene collection + element inventory and the
     // baked-crust compositor cache. The ViewModel exposes Scenes/StagedScene/LiveScene
     // on top of it; the scene collection itself lives here.
-    private SceneGraph _sceneGraph = null!;
+    // Field-initialized, NOT ctor-assigned: the ctor touches Scenes (CollectionChanged
+    // wiring) before its later statements run — first-ctor-line NRE if the graph isn't
+    // born yet (startup crash regression from TASK 31, 2026-09-01; headless RealApp
+    // tests never ran it, so it waited for the first native launch).
+    private SceneGraph _sceneGraph = new();
     private readonly TransitionService _transition = new();
 
     private WebView2Manager? _webView2Manager;
@@ -294,7 +298,6 @@ public partial class MainViewModel : ViewModelBase
 
         _chatLayer = new ChatOverlayLayer(new ChatBoxRenderer());
 
-        _sceneGraph = new SceneGraph();
         _rtmpUrlProvider = () => _reusableStreamUrl; // TASK 5: the reusable stream's ingest URL
         _framePump = new FramePump(
             sceneProvider: () => StagedScene,
diff --git a/ai.md b/ai.md
index e5209ef..707757f 100644
--- a/ai.md
+++ b/ai.md
@@ -126,9 +126,14 @@ the Socials fediverse-heal roundtrip, AboutHubTests, NotificationAreaIntegration
 GlobalHotkeyTests + HotkeyConfigTests (TASK 20), WebcamMenuGateTests (TASK 26), ChatLayerGateTests
 (TASK 27), BroadcastPullOutTests (TASK 29), DefaultRecordFolder fallback (TASK 30), WebView2ManagerTests
 (TASK 17), RecordingFileTests + OnAirSignTests (TASK 18) —
-**247 total (245 pass — the 2 pre-existing known failures
-`AudioPipelineTests.Mix_HonorsProviderGains…` + `RoundClipInteractionTests.Round_Clip_Corner_Is_Grabbable…`
-are NOT regressions; see HANDOFF.md. Run test classes individually — the full-suite vstest run hangs.)**
+**247 total (246 pass — the ONE remaining known failure is
+`AudioPipelineTests.Mix_HonorsProviderGains…` (the creator-declared known, suspected WASAPI
+channel declaration/init). The former "known" `RoundClipInteractionTests.Round_Clip_Corner_Is_Grabbable…`
+was root-caused and FIXED 2026-09-01: two stale-test layers from the component refactor (namescoped
+`FindName` + `VisualTreeHelper.HitTest` used where `UIElement.InputHitTest` models input — see
+MyMistakes recipe), no product bug. Full-suite vstest still hangs headless — but per-class runs
+THROUGH THE WINDOWS dotnet.exe HOST DO EXECUTE the real-`MainWindow`/RealApp tests fine (verified
+same day; the old "GUI suites can't run from here" was an overstatement.)**
 
 Reward-event capture (monetization awareness, see the Monetization section) will add its integration
 tests here when it ships: one real chat-poll payload containing all seven reward event types →
diff --git a/ytLive.Tests/RoundClipInteractionTests.cs b/ytLive.Tests/RoundClipInteractionTests.cs
index 3e0384f..9027829 100644
--- a/ytLive.Tests/RoundClipInteractionTests.cs
+++ b/ytLive.Tests/RoundClipInteractionTests.cs
@@ -34,6 +34,7 @@ public sealed class RoundClipInteractionTests
         _app.Run(Run);
     }
 
+
     private void Run()
     {
         // Never let the real MainWindow read/write the user's actual layout DB —
@@ -62,8 +63,12 @@ public sealed class RoundClipInteractionTests
             vm.SelectedElement = webcam;
             window.UpdateLayout();
 
-            var previewGrid = (Grid)window.FindName("PreviewGrid")!;
-            var canvasGrid = (Grid)window.FindName("CanvasGrid")!;
+            // PreviewGrid/CanvasGrid moved into Controls/PreviewPane.xaml during the
+            // component refactor — a UserControl owns its own namescope, so window.FindName
+            // returns null for them. Resolve through the pane (found by its window-level name).
+            var pane = (System.Windows.Controls.UserControl)window.FindName("PreviewPane")!;
+            var previewGrid = (Grid)pane.FindName("PreviewGrid")!;
+            var canvasGrid = (Grid)pane.FindName("CanvasGrid")!;
             var toWindow = canvasGrid.TransformToVisual(window);
 
             var corner = new Point(webcam.X + webcam.Width, webcam.Y + webcam.Height);
@@ -78,11 +83,16 @@ public sealed class RoundClipInteractionTests
                 // A click on the corner must land inside the preview (descendant
                 // of PreviewGrid); otherwise Window_PreviewMouseLeftButtonDown
                 // deselects the source and the handle can never be grabbed.
-                var hit = VisualTreeHelper.HitTest(window, cornerInWindow);
-                var grabbable = hit != null && IsDescendantOf(hit.VisualHit, previewGrid);
+                // UIElement.InputHitTest IS the input pipeline — what Mouse uses.
+                // Do NOT use VisualTreeHelper.HitTest here: it returned the window's
+                // non-hit-testable WebViewHostPanel overlay for EVERY point (it does
+                // not model IsHitTestVisible input semantics) — the bug this test
+                // "found" for months was this wrong API (root-caused 2026-09-01).
+                var hit = window.InputHitTest(cornerInWindow) as DependencyObject;
+                var grabbable = hit != null && IsDescendantOf(hit, previewGrid);
 
                 Assert.True(grabbable,
-                    $"{shape}: corner click fell through to '{hit?.VisualHit.GetType().Name ?? "null"}' " +
+                    $"{shape}: corner click fell through to '{hit?.GetType().Name ?? "null"}' " +
                     "so the source gets deselected before the resize handler runs");
             }