diff --git a/src/app/browser-bridge.ts b/src/app/browser-bridge.ts
index e4041c676..1b3951e33 100644
--- a/src/app/browser-bridge.ts
+++ b/src/app/browser-bridge.ts
@@ -2,10 +2,17 @@ import type { ChatTransport, UIMessage } from 'ai'
 
 import type { EditorStore } from '@/app/editor/session/create'
 
+export interface OpenPencilTestHooks {
+  writeCount?: () => number
+  mockHandle?: FileSystemFileHandle
+  savedOpen?: Window['open']
+}
+
 export interface OpenPencilWindowAPI {
   store?: EditorStore
   setChatTransport?: (factory: () => ChatTransport<UIMessage>) => void
   openFile?: (path: string) => Promise<void>
+  test?: OpenPencilTestHooks
 }
 
 declare global {
diff --git a/src/global.d.ts b/src/global.d.ts
index a12bf4a75..131983748 100644
--- a/src/global.d.ts
+++ b/src/global.d.ts
@@ -38,9 +38,6 @@ declare global {
         blob(): Promise<Blob>
       }[]
     >
-    __TEST_WRITE_COUNT__?(): number
-    __TEST_MOCK_HANDLE__?: FileSystemFileHandle
-    __savedOpen?: Window['open']
     mockWindowOpen?(url: string): void
   }
 }
diff --git a/tests/e2e/autosave.spec.ts b/tests/e2e/autosave.spec.ts
index 8a5fcfa57..597e42176 100644
--- a/tests/e2e/autosave.spec.ts
+++ b/tests/e2e/autosave.spec.ts
@@ -31,8 +31,8 @@ test('autosave triggers after scene changes with a file handle', async () => {
       createWritable: async () => mockWritable
     } as FileSystemFileHandle
 
-    window.__TEST_WRITE_COUNT__ = () => writes
-    window.__TEST_MOCK_HANDLE__ = mockHandle
+    window.openPencil ??= {}
+    window.openPencil.test = { writeCount: () => writes, mockHandle }
 
     return writes
   })
diff --git a/tests/e2e/chat/panel.spec.ts b/tests/e2e/chat/panel.spec.ts
index 3e5100c42..06f146ca6 100644
--- a/tests/e2e/chat/panel.spec.ts
+++ b/tests/e2e/chat/panel.spec.ts
@@ -244,7 +244,8 @@ test('"Get API key" link opens external URL via window.open', async () => {
   const openedUrls: string[] = []
   await page.exposeFunction('mockWindowOpen', (url: string) => openedUrls.push(url))
   await page.evaluate(() => {
-    window.__savedOpen = window.open
+    window.openPencil ??= {}
+    window.openPencil.test = { ...window.openPencil.test, savedOpen: window.open }
     window.open = (url: string | URL) => {
       window.mockWindowOpen?.(String(url))
       return null
@@ -260,6 +261,7 @@ test('"Get API key" link opens external URL via window.open', async () => {
 
   // Restore
   await page.evaluate(() => {
-    if (window.__savedOpen) window.open = window.__savedOpen
+    const savedOpen = window.openPencil?.test?.savedOpen
+    if (savedOpen) window.open = savedOpen
   })
 })