테스트/린트 안정화: 버튼 쿼리 모호성 제거, 훅 deps 보강, vi.spyOn 모킹, 멀티선택 Moveable 간섭 방지 재확인, 스냅 우선순위 회귀 그린

components/wysiwyg/WysiwygBuilder.layers.acceptance.test.tsx

@@ -6,8 +6,8 @@ describe('WYSIWYG Builder - Layers acceptance', () => {
   it('visible toggle reflects on layer button state', async () => {
     render(<WysiwygBuilderPage />)
     // add two texts
-    fireEvent.click(screen.getByRole('button', { name: /Add Text/i }))
-    fireEvent.click(screen.getByRole('button', { name: /Add Text/i }))
+    fireEvent.click(screen.getByRole('button', { name: /^Add Text$/i }))
+    fireEvent.click(screen.getByRole('button', { name: /^Add Text$/i }))
 
     // 레이어 패널에서 visible 토글 버튼 상태만 검증
     const hideBtn = screen.getByTestId('layer-hide-base')
@@ -18,4 +18,30 @@ describe('WYSIWYG Builder - Layers acceptance', () => {
     fireEvent.click(hideBtn)
     expect(hideBtn).toHaveAttribute('aria-pressed', 'false')
   })
+
+  it('layer order changes reflect in Canvas DOM stacking order', async () => {
+    render(<WysiwygBuilderPage />)
+    // Add two layers, each with one text object labeled L1, L2
+    fireEvent.click(screen.getByRole('button', { name: /Add Layer/i }))
+    fireEvent.click(screen.getByRole('button', { name: /Add Layer/i }))
+
+    const t1 = await screen.findByText('L1')
+    const t2 = await screen.findByText('L2')
+
+    // Initially, later layer (L2) should be on top, thus follow L1 in DOM order
+    const pos1 = t1.compareDocumentPosition(t2)
+    expect(pos1 & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy()
+
+    // Move L2 up (towards front doesn't change since it's already last), then move L2 down to go below L1
+    const up2 = screen.getByTestId('layer-up-layer-2')
+    const down2 = screen.getByTestId('layer-down-layer-2')
+    // up no-op when at top boundary (safe click)
+    fireEvent.click(up2)
+    // now move it down once (below)
+    fireEvent.click(down2)
+
+    // After moving L2 down, L1 should now come after L2 in DOM order (L1 on top)
+    const pos2 = t2.compareDocumentPosition(t1)
+    expect(pos2 & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy()
+  })
 })