fix(browser): scope background page mount admission

src/renderer/src/components/browser-pane/assemble-chrome/browser-workspace-pane.tsx

@@ -22,7 +22,10 @@ import { WorkspaceDocPagePane } from '../workspace-doc/workspace-doc-page-pane'
 import { DeferredBrowserContent } from './DeferredBrowserContent'
 import { isBrowserPagePanePaintable } from '../host-guest/browser-page-paintability'
 import { SshRoutedBrowserPageGate } from './ssh-routed-browser-page-gate'
-import { useAnyBrowserPageMountAdmission } from '../host-guest/browser-page-mount-admission'
+import {
+  isBrowserPageMountAdmitted,
+  useAnyBrowserPageMountAdmission
+} from '../host-guest/browser-page-mount-admission'
 
 export default function BrowserPane({
   browserTab,
@@ -168,7 +171,9 @@ export default function BrowserPane({
                   key={page.id}
                   retainMounted={isWorktreeActive}
                   mountEligible={isBrowserPagePanePaintable({
-                    isActive: (isActive && page.id === activeBrowserPageId) || hasAdmittedPage,
+                    isActive:
+                      (isActive && page.id === activeBrowserPageId) ||
+                      (hasAdmittedPage && isBrowserPageMountAdmitted(page.id)),
                     isAutomationVisible: automationVisiblePageIds.has(page.id),
                     isMobileDriven: mobileDrivenPageIds.has(page.id),
                     hasRemoteViewer: remotelyViewedPageIds.has(page.id)

src/renderer/src/components/browser-pane/host-guest/browser-page-mount-admission.ts

@@ -6,6 +6,10 @@ const admittedPageIds = new Set<string>()
 const listeners = new Set<() => void>()
 let version = 0
 
+export function isBrowserPageMountAdmitted(pageId: string): boolean {
+  return admittedPageIds.has(pageId)
+}
+
 function emit(): void {
   version += 1
   for (const listener of listeners) {
@@ -36,11 +40,11 @@ export function useBrowserPageMountAdmission(pageId: string): boolean {
     },
     () => {
       void version
-      return admittedPageIds.has(pageId)
+      return isBrowserPageMountAdmitted(pageId)
     },
     () => false
   )
-  return admittedPageIds.has(pageId)
+  return isBrowserPageMountAdmitted(pageId)
 }
 
 export function useAnyBrowserPageMountAdmission(pageIds: readonly string[]): boolean {
@@ -51,9 +55,9 @@ export function useAnyBrowserPageMountAdmission(pageIds: readonly string[]): boo
     },
     () => {
       void version
-      return pageIds.some((pageId) => admittedPageIds.has(pageId))
+      return pageIds.some(isBrowserPageMountAdmitted)
     },
     () => false
   )
-  return pageIds.some((pageId) => admittedPageIds.has(pageId))
+  return pageIds.some(isBrowserPageMountAdmitted)
 }

src/renderer/src/store/slices/browser/browser-close-actions.ts

@@ -13,6 +13,7 @@ import { closeRemoteBrowserPageInOwningEnvironment } from './browser-remote-clos
 import { releaseDocPreviewGrant } from '@/lib/doc-preview-grants'
 import { destroyWorkspaceWebviews } from '../browser-webview-cleanup'
 import { omitRecordKeys } from '../worktrees/teardown/record-key-omission'
+import { releaseBrowserPageMount } from '@/components/browser-pane/host-guest/browser-page-mount-admission'
 
 export function createBrowserCloseActions(
   set: BrowserSliceSet,
@@ -28,6 +29,7 @@ export function createBrowserCloseActions(
       // grant is the only authority the preview scheme honors — a closed document must stop being
       // readable, and it must stop being readable even if the reducer bails out below.
       let docPageIdsToRelease: string[] = []
+      let closedPagesForMountRelease: string[] = []
       let activeBrowserWorktreeIdToNotify: string | null = null
       set((s) => {
         let owningWorktreeId: string | null = null
@@ -49,6 +51,7 @@ export function createBrowserCloseActions(
         }
 
         const closedPages = s.browserPagesByWorkspace[tabId] ?? []
+        closedPagesForMountRelease = closedPages.map((page) => page.id)
         const nextBrowserPagesByWorkspace = { ...s.browserPagesByWorkspace }
         delete nextBrowserPagesByWorkspace[tabId]
         const nextBrowserAnnotationsByPageId = { ...s.browserAnnotationsByPageId }
@@ -179,6 +182,9 @@ export function createBrowserCloseActions(
       for (const docPageId of docPageIdsToRelease) {
         releaseDocPreviewGrant(docPageId)
       }
+      for (const pageId of closedPagesForMountRelease) {
+        releaseBrowserPageMount(pageId)
+      }
 
       for (const tabs of Object.values(get().unifiedTabsByWorktree)) {
         const workspaceItem = tabs.find(