test: cover tab drag root cleanup wiring

Co-authored-by: Orca <help@stably.ai>

src/renderer/src/components/tab-group/TabGroupSplitLayout.test.ts

@@ -104,6 +104,19 @@ describe('TabGroupSplitLayout', () => {
     )
   })
 
+  it('wires the split layout root to drag cleanup ownership', () => {
+    const element = TabGroupSplitLayout({
+      layout: { type: 'leaf', groupId: 'group-1' },
+      worktreeId: 'wt-1',
+      focusedGroupId: 'group-1',
+      isWorktreeActive: true
+    })
+
+    const layoutWrapper = element.props.children[0]
+
+    expect(layoutWrapper.props.ref).toBe(setDragRootNodeMock)
+  })
+
   it('only reserves top-right header space for the floating explorer toggle', () => {
     const element = TabGroupSplitLayout({
       layout: {