fix: avoid stacking browser download handlers (#2879)

src/main/window/attach-main-window-services.test.ts

@@ -171,7 +171,8 @@ describe('attachMainWindowServices', () => {
       setPermissionRequestHandler: setPermissionRequestHandlerMock,
       setPermissionCheckHandler: setPermissionCheckHandlerMock,
       setDisplayMediaRequestHandler: setDisplayMediaRequestHandlerMock,
-      on: vi.fn()
+      on: vi.fn(),
+      removeListener: vi.fn()
     })
     systemPreferencesAskForMediaAccessMock.mockResolvedValue(true)
     systemPreferencesGetMediaAccessStatusMock.mockReturnValue('granted')
@@ -316,7 +317,8 @@ describe('attachMainWindowServices', () => {
       setPermissionRequestHandler: setPermissionRequestHandlerMock,
       setPermissionCheckHandler: setPermissionCheckHandlerMock,
       setDisplayMediaRequestHandler: setDisplayMediaRequestHandlerMock,
-      on: browserSessionOnMock
+      on: browserSessionOnMock,
+      removeListener: vi.fn()
     })
 
     const mainWindowOnMock = vi.fn()
@@ -378,12 +380,38 @@ describe('attachMainWindowServices', () => {
     })
   })
 
+  it('replaces the persistent browser-session download handler on re-attach', () => {
+    const browserSessionOnMock = vi.fn()
+    const browserSessionRemoveListenerMock = vi.fn()
+    sessionFromPartitionMock.mockReturnValue({
+      setPermissionRequestHandler: setPermissionRequestHandlerMock,
+      setPermissionCheckHandler: setPermissionCheckHandlerMock,
+      setDisplayMediaRequestHandler: setDisplayMediaRequestHandlerMock,
+      on: browserSessionOnMock,
+      removeListener: browserSessionRemoveListenerMock
+    })
+
+    attachMainWindowServices(createMainWindow() as never, createStore(), createRuntime() as never)
+    attachMainWindowServices(createMainWindow() as never, createStore(), createRuntime() as never)
+
+    const downloadOnCalls = browserSessionOnMock.mock.calls.filter(
+      ([eventName]) => eventName === 'will-download'
+    )
+    const downloadRemoveCalls = browserSessionRemoveListenerMock.mock.calls.filter(
+      ([eventName]) => eventName === 'will-download'
+    )
+    expect(downloadOnCalls).toHaveLength(2)
+    expect(downloadRemoveCalls).toHaveLength(2)
+    expect(downloadRemoveCalls[1][1]).toBe(downloadOnCalls[0][1])
+  })
+
   it('clears browser guest registrations when the main window closes', () => {
     sessionFromPartitionMock.mockReturnValue({
       setPermissionRequestHandler: setPermissionRequestHandlerMock,
       setPermissionCheckHandler: setPermissionCheckHandlerMock,
       setDisplayMediaRequestHandler: setDisplayMediaRequestHandlerMock,
-      on: vi.fn()
+      on: vi.fn(),
+      removeListener: vi.fn()
     })
     const mainWindowOnMock = vi.fn()
     const mainWindow = createMainWindow()

src/main/window/attach-main-window-services.ts

@@ -2,7 +2,7 @@
 import { randomUUID } from 'node:crypto'
 
 import { app, ipcMain, session } from 'electron'
-import type { BrowserWindow } from 'electron'
+import type { BrowserWindow, Session } from 'electron'
 import type { Store } from '../persistence'
 import type { CreateWorktreeResult, WorktreeStartupLaunch } from '../../shared/types'
 import { ORCA_BROWSER_PARTITION } from '../../shared/constants'
@@ -196,12 +196,7 @@ export function attachMainWindowServices(
     // signature while still denying the request.
     callback({ video: undefined, audio: undefined })
   })
-  browserSession.on('will-download', (_event, item, webContents) => {
-    // Why: browser-tab downloads need explicit product UX before arbitrary sites
-    // can write files through Orca. Pause the item and route it through
-    // BrowserManager so the user must explicitly accept the save path first.
-    browserManager.handleGuestWillDownload({ guestWebContentsId: webContents.id, item })
-  })
+  registerBrowserDownloadHandler(browserSession)
 
   mainWindow.on('closed', () => {
     // Why: parked browser webviews can outlive the visible tab body until the
@@ -212,6 +207,24 @@ export function attachMainWindowServices(
   })
 }
 
+function handleBrowserWillDownload(
+  _event: Electron.Event,
+  item: Electron.DownloadItem,
+  webContents: Electron.WebContents
+): void {
+  // Why: browser-tab downloads need explicit product UX before arbitrary sites
+  // can write files through Orca. Pause the item and route it through
+  // BrowserManager so the user must explicitly accept the save path first.
+  browserManager.handleGuestWillDownload({ guestWebContentsId: webContents.id, item })
+}
+
+function registerBrowserDownloadHandler(browserSession: Session): void {
+  // Why: browser sessions are process-persistent while main windows can be
+  // recreated; replace the named handler so re-attach does not stack listeners.
+  browserSession.removeListener('will-download', handleBrowserWillDownload)
+  browserSession.on('will-download', handleBrowserWillDownload)
+}
+
 function registerAppReloadHandler(
   mainWindow: BrowserWindow,
   onBeforeRendererReload?: (args: { webContentsId: number; ignoreCache: boolean }) => void