diff --git a/apps/desktop/src/components/assistant-ui/thread/block-direction.test.tsx b/apps/desktop/src/components/assistant-ui/thread/block-direction.test.tsx
index cc63d4fbb..227f9e63b 100644
--- a/apps/desktop/src/components/assistant-ui/thread/block-direction.test.tsx
+++ b/apps/desktop/src/components/assistant-ui/thread/block-direction.test.tsx
@@ -25,6 +25,7 @@ vi.stubGlobal('requestAnimationFrame', (callback: FrameRequestCallback) =>
   window.setTimeout(() => callback(performance.now()), 0)
 )
 vi.stubGlobal('cancelAnimationFrame', (id: number) => window.clearTimeout(id))
+vi.stubGlobal('CSS', { escape: (str: string) => str })
 
 Element.prototype.scrollTo = function scrollTo() {}
 
diff --git a/apps/desktop/src/components/assistant-ui/thread/streaming.test.tsx b/apps/desktop/src/components/assistant-ui/thread/streaming.test.tsx
index 3759f469e..fb844df0d 100644
--- a/apps/desktop/src/components/assistant-ui/thread/streaming.test.tsx
+++ b/apps/desktop/src/components/assistant-ui/thread/streaming.test.tsx
@@ -48,6 +48,7 @@ vi.stubGlobal('requestAnimationFrame', (callback: FrameRequestCallback) =>
   window.setTimeout(() => callback(performance.now()), 0)
 )
 vi.stubGlobal('cancelAnimationFrame', (id: number) => window.clearTimeout(id))
+vi.stubGlobal('CSS', { escape: (str: string) => str })
 
 Element.prototype.scrollTo = function scrollTo() {}
 
diff --git a/apps/desktop/src/components/assistant-ui/thread/user-message-edit.test.tsx b/apps/desktop/src/components/assistant-ui/thread/user-message-edit.test.tsx
index 914fc043b..3d1e7a69b 100644
--- a/apps/desktop/src/components/assistant-ui/thread/user-message-edit.test.tsx
+++ b/apps/desktop/src/components/assistant-ui/thread/user-message-edit.test.tsx
@@ -28,6 +28,7 @@ vi.stubGlobal('requestAnimationFrame', (callback: FrameRequestCallback) =>
   window.setTimeout(() => callback(performance.now()), 0)
 )
 vi.stubGlobal('cancelAnimationFrame', (id: number) => window.clearTimeout(id))
+vi.stubGlobal('CSS', { escape: (str: string) => str })
 
 Element.prototype.scrollTo = function scrollTo() {}