fix: open image in new tab on cloud fetches as blob to avoid GCS auto-download (#9122)

## Summary

Fix "Open Image" on cloud opening a new tab that auto-downloads the
asset instead of displaying it inline.

## Changes

- **What**: Add `openFileInNewTab()` to `downloadUtil.ts` that fetches
cross-origin URLs as blobs before opening in a new tab, avoiding GCS
`Content-Disposition: attachment` redirects. Opens the blank tab
synchronously to preserve user-gesture activation (avoiding popup
blockers), then navigates to a blob URL once the fetch completes. Blob
URLs are revoked after 60s or immediately if the tab was closed. Update
both call sites (`useImageMenuOptions` and `litegraphService`) to use
the new function.

## Review Focus

- The synchronous `window.open('', '_blank')` before the async fetch is
intentional to preserve user-gesture context and avoid popup blockers.
- Blob URL revocation strategy: 60s timeout for successful opens,
immediate revoke if tab was closed, tab closed on fetch failure.
- Shared `fetchAsBlob()` helper is also used by the existing
`downloadViaBlobFetch`.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9122-fix-open-image-in-new-tab-on-cloud-fetches-as-blob-to-avoid-GCS-auto-download-3106d73d365081a3bfa6eb7d77fde99f)
by [Unito](https://www.unito.io)

src/base/common/downloadUtil.test.ts

@@ -2,17 +2,28 @@ import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
 import {
   downloadFile,
-  extractFilenameFromContentDisposition
+  extractFilenameFromContentDisposition,
+  openFileInNewTab
 } from '@/base/common/downloadUtil'
 
-let mockIsCloud = false
+const { mockIsCloud } = vi.hoisted(() => ({
+  mockIsCloud: { value: false }
+}))
 
 vi.mock('@/platform/distribution/types', () => ({
   get isCloud() {
-    return mockIsCloud
+    return mockIsCloud.value
   }
 }))
 
+vi.mock('@/i18n', () => ({
+  t: (key: string) => key
+}))
+
+vi.mock('@/platform/updates/common/toastStore', () => ({
+  useToastStore: vi.fn(() => ({ addAlert: vi.fn() }))
+}))
+
 // Global stubs
 const createObjectURLSpy = vi
   .spyOn(URL, 'createObjectURL')
@@ -26,7 +37,7 @@ describe('downloadUtil', () => {
   let fetchMock: ReturnType<typeof vi.fn>
 
   beforeEach(() => {
-    mockIsCloud = false
+    mockIsCloud.value = false
     fetchMock = vi.fn()
     vi.stubGlobal('fetch', fetchMock)
     createObjectURLSpy.mockClear().mockReturnValue('blob:mock-url')
@@ -154,7 +165,7 @@ describe('downloadUtil', () => {
     })
 
     it('streams downloads via blob when running in cloud', async () => {
-      mockIsCloud = true
+      mockIsCloud.value = true
       const testUrl = 'https://storage.googleapis.com/bucket/file.bin'
       const blob = new Blob(['test'])
       const blobFn = vi.fn().mockResolvedValue(blob)
@@ -173,6 +184,7 @@ describe('downloadUtil', () => {
       expect(fetchMock).toHaveBeenCalledWith(testUrl)
       const fetchPromise = fetchMock.mock.results[0].value as Promise<Response>
       await fetchPromise
+      await Promise.resolve() // let fetchAsBlob return
       const blobPromise = blobFn.mock.results[0].value as Promise<Blob>
       await blobPromise
       await Promise.resolve()
@@ -183,7 +195,7 @@ describe('downloadUtil', () => {
     })
 
     it('logs an error when cloud fetch fails', async () => {
-      mockIsCloud = true
+      mockIsCloud.value = true
       const testUrl = 'https://storage.googleapis.com/bucket/missing.bin'
       const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
       fetchMock.mockResolvedValue({
@@ -197,14 +209,15 @@ describe('downloadUtil', () => {
       expect(fetchMock).toHaveBeenCalledWith(testUrl)
       const fetchPromise = fetchMock.mock.results[0].value as Promise<Response>
       await fetchPromise
-      await Promise.resolve()
+      await Promise.resolve() // let fetchAsBlob throw
+      await Promise.resolve() // let .catch handler run
       expect(consoleSpy).toHaveBeenCalled()
       expect(createObjectURLSpy).not.toHaveBeenCalled()
       consoleSpy.mockRestore()
     })
 
     it('uses filename from Content-Disposition header in cloud mode', async () => {
-      mockIsCloud = true
+      mockIsCloud.value = true
       const testUrl = 'https://storage.googleapis.com/bucket/abc123.png'
       const blob = new Blob(['test'])
       const blobFn = vi.fn().mockResolvedValue(blob)
@@ -223,6 +236,7 @@ describe('downloadUtil', () => {
       expect(fetchMock).toHaveBeenCalledWith(testUrl)
       const fetchPromise = fetchMock.mock.results[0].value as Promise<Response>
       await fetchPromise
+      await Promise.resolve() // let fetchAsBlob return
       const blobPromise = blobFn.mock.results[0].value as Promise<Blob>
       await blobPromise
       await Promise.resolve()
@@ -231,7 +245,7 @@ describe('downloadUtil', () => {
     })
 
     it('uses RFC 5987 filename from Content-Disposition header', async () => {
-      mockIsCloud = true
+      mockIsCloud.value = true
       const testUrl = 'https://storage.googleapis.com/bucket/abc123.png'
       const blob = new Blob(['test'])
       const blobFn = vi.fn().mockResolvedValue(blob)
@@ -253,6 +267,7 @@ describe('downloadUtil', () => {
 
       const fetchPromise = fetchMock.mock.results[0].value as Promise<Response>
       await fetchPromise
+      await Promise.resolve() // let fetchAsBlob return
       const blobPromise = blobFn.mock.results[0].value as Promise<Blob>
       await blobPromise
       await Promise.resolve()
@@ -260,7 +275,7 @@ describe('downloadUtil', () => {
     })
 
     it('falls back to provided filename when Content-Disposition is missing', async () => {
-      mockIsCloud = true
+      mockIsCloud.value = true
       const testUrl = 'https://storage.googleapis.com/bucket/abc123.png'
       const blob = new Blob(['test'])
       const blobFn = vi.fn().mockResolvedValue(blob)
@@ -278,6 +293,7 @@ describe('downloadUtil', () => {
 
       const fetchPromise = fetchMock.mock.results[0].value as Promise<Response>
       await fetchPromise
+      await Promise.resolve() // let fetchAsBlob return
       const blobPromise = blobFn.mock.results[0].value as Promise<Blob>
       await blobPromise
       await Promise.resolve()
@@ -285,6 +301,99 @@ describe('downloadUtil', () => {
     })
   })
 
+  describe('openFileInNewTab', () => {
+    let windowOpenSpy: ReturnType<typeof vi.spyOn>
+
+    beforeEach(() => {
+      vi.useFakeTimers()
+      windowOpenSpy = vi.spyOn(window, 'open').mockImplementation(() => null)
+    })
+
+    afterEach(() => {
+      vi.useRealTimers()
+    })
+
+    it('opens URL directly when not in cloud mode', async () => {
+      mockIsCloud.value = false
+      const testUrl = 'https://example.com/image.png'
+
+      await openFileInNewTab(testUrl)
+
+      expect(windowOpenSpy).toHaveBeenCalledWith(testUrl, '_blank')
+      expect(fetchMock).not.toHaveBeenCalled()
+    })
+
+    it('opens blank tab synchronously then navigates to blob URL in cloud mode', async () => {
+      mockIsCloud.value = true
+      const testUrl = 'https://storage.googleapis.com/bucket/image.png'
+      const blob = new Blob(['test'], { type: 'image/png' })
+      const mockTab = { location: { href: '' }, closed: false, close: vi.fn() }
+      windowOpenSpy.mockReturnValue(mockTab as unknown as Window)
+      fetchMock.mockResolvedValue({
+        ok: true,
+        blob: vi.fn().mockResolvedValue(blob)
+      } as unknown as Response)
+
+      await openFileInNewTab(testUrl)
+
+      expect(windowOpenSpy).toHaveBeenCalledWith('', '_blank')
+      expect(fetchMock).toHaveBeenCalledWith(testUrl)
+      expect(createObjectURLSpy).toHaveBeenCalledWith(blob)
+      expect(mockTab.location.href).toBe('blob:mock-url')
+    })
+
+    it('revokes blob URL after timeout in cloud mode', async () => {
+      mockIsCloud.value = true
+      const blob = new Blob(['test'], { type: 'image/png' })
+      const mockTab = { location: { href: '' }, closed: false, close: vi.fn() }
+      windowOpenSpy.mockReturnValue(mockTab as unknown as Window)
+      fetchMock.mockResolvedValue({
+        ok: true,
+        blob: vi.fn().mockResolvedValue(blob)
+      } as unknown as Response)
+
+      await openFileInNewTab('https://example.com/image.png')
+
+      expect(revokeObjectURLSpy).not.toHaveBeenCalled()
+      vi.advanceTimersByTime(60_000)
+      expect(revokeObjectURLSpy).toHaveBeenCalledWith('blob:mock-url')
+    })
+
+    it('closes blank tab and logs error when cloud fetch fails', async () => {
+      mockIsCloud.value = true
+      const testUrl = 'https://storage.googleapis.com/bucket/missing.png'
+      const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+      const mockTab = { location: { href: '' }, closed: false, close: vi.fn() }
+      windowOpenSpy.mockReturnValue(mockTab as unknown as Window)
+      fetchMock.mockResolvedValue({
+        ok: false,
+        status: 404
+      } as unknown as Response)
+
+      await openFileInNewTab(testUrl)
+
+      expect(mockTab.close).toHaveBeenCalled()
+      expect(consoleSpy).toHaveBeenCalled()
+      consoleSpy.mockRestore()
+    })
+
+    it('revokes blob URL immediately if tab was closed by user', async () => {
+      mockIsCloud.value = true
+      const blob = new Blob(['test'], { type: 'image/png' })
+      const mockTab = { location: { href: '' }, closed: true, close: vi.fn() }
+      windowOpenSpy.mockReturnValue(mockTab as unknown as Window)
+      fetchMock.mockResolvedValue({
+        ok: true,
+        blob: vi.fn().mockResolvedValue(blob)
+      } as unknown as Response)
+
+      await openFileInNewTab('https://example.com/image.png')
+
+      expect(revokeObjectURLSpy).toHaveBeenCalledWith('blob:mock-url')
+      expect(mockTab.location.href).toBe('')
+    })
+  })
+
   describe('extractFilenameFromContentDisposition', () => {
     it('returns null for null header', () => {
       expect(extractFilenameFromContentDisposition(null)).toBeNull()

src/base/common/downloadUtil.ts

@@ -1,7 +1,9 @@
 /**
  * Utility functions for downloading files
  */
+import { t } from '@/i18n'
 import { isCloud } from '@/platform/distribution/types'
+import { useToastStore } from '@/platform/updates/common/toastStore'
 
 // Constants
 const DEFAULT_DOWNLOAD_FILENAME = 'download.png'
@@ -112,14 +114,23 @@ export function extractFilenameFromContentDisposition(
   return null
 }
 
-const downloadViaBlobFetch = async (
+/**
+ * Fetch a URL and return its body as a Blob.
+ * Shared by download and open-in-new-tab cloud paths.
+ */
+async function fetchAsBlob(url: string): Promise<Response> {
+  const response = await fetch(url)
+  if (!response.ok) {
+    throw new Error(`Failed to fetch ${url}: ${response.status}`)
+  }
+  return response
+}
+
+async function downloadViaBlobFetch(
   href: string,
   fallbackFilename: string
-): Promise<void> => {
-  const response = await fetch(href)
-  if (!response.ok) {
-    throw new Error(`Failed to fetch ${href}: ${response.status}`)
-  }
+): Promise<void> {
+  const response = await fetchAsBlob(href)
 
   // Try to get filename from Content-Disposition header (set by backend)
   const contentDisposition = response.headers.get('Content-Disposition')
@@ -129,3 +140,44 @@ const downloadViaBlobFetch = async (
   const blob = await response.blob()
   downloadBlob(headerFilename ?? fallbackFilename, blob)
 }
+
+/**
+ * Open a file URL in a new browser tab.
+ * On cloud, fetches the resource as a blob first to avoid GCS redirects
+ * that would trigger an auto-download instead of displaying the file.
+ *
+ * Opens the tab synchronously to preserve the user-gesture context
+ * (browsers block window.open after an await), then navigates it to
+ * the blob URL once the fetch completes.
+ */
+export async function openFileInNewTab(url: string): Promise<void> {
+  if (!isCloud) {
+    window.open(url, '_blank')
+    return
+  }
+
+  // Open immediately to preserve user-gesture activation.
+  const tab = window.open('', '_blank')
+
+  try {
+    const response = await fetchAsBlob(url)
+    const blob = await response.blob()
+    const blobUrl = URL.createObjectURL(blob)
+
+    if (tab && !tab.closed) {
+      tab.location.href = blobUrl
+      // Revoke after the tab has had time to load the blob.
+      setTimeout(() => URL.revokeObjectURL(blobUrl), 60_000)
+    } else {
+      URL.revokeObjectURL(blobUrl)
+    }
+  } catch (error) {
+    tab?.close()
+    console.error('Failed to open image:', error)
+    useToastStore().addAlert(
+      t('toastMessages.errorOpenImage', {
+        error: error instanceof Error ? error.message : String(error)
+      })
+    )
+  }
+}

src/composables/graph/useImageMenuOptions.ts

@@ -1,6 +1,6 @@
 import { useI18n } from 'vue-i18n'
 
-import { downloadFile } from '@/base/common/downloadUtil'
+import { downloadFile, openFileInNewTab } from '@/base/common/downloadUtil'
 import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import { useCommandStore } from '@/stores/commandStore'
 
@@ -23,7 +23,7 @@ export function useImageMenuOptions() {
     if (!img) return
     const url = new URL(img.src)
     url.searchParams.delete('preview')
-    window.open(url.toString(), '_blank')
+    void openFileInNewTab(url.toString())
   }
 
   const copyImage = async (node: LGraphNode) => {

src/locales/en/main.json

@@ -1910,6 +1910,7 @@
     "nodeDefinitionsUpdated": "Node definitions updated",
     "errorSaveSetting": "Error saving setting {id}: {err}",
     "errorCopyImage": "Error copying image: {error}",
+    "errorOpenImage": "Error opening image: {error}",
     "noTemplatesToExport": "No templates to export",
     "failedToFetchLogs": "Failed to fetch server logs",
     "migrateToLitegraphReroute": "Reroute nodes will be removed in future versions. Click to migrate to litegraph-native reroute.",

src/services/litegraphService.ts

@@ -1,6 +1,6 @@
 import _ from 'es-toolkit/compat'
 
-import { downloadFile } from '@/base/common/downloadUtil'
+import { downloadFile, openFileInNewTab } from '@/base/common/downloadUtil'
 import { useSelectedLiteGraphItems } from '@/composables/canvas/useSelectedLiteGraphItems'
 import { useSubgraphOperations } from '@/composables/graph/useSubgraphOperations'
 import { useNodeAnimatedImage } from '@/composables/node/useNodeAnimatedImage'
@@ -686,7 +686,7 @@ export const useLitegraphService = () => {
               callback: () => {
                 const url = new URL(img.src)
                 url.searchParams.delete('preview')
-                window.open(url, '_blank')
+                void openFileInNewTab(url.toString())
               }
             },
             ...getCopyImageOption(img),