diff --git a/src/main/ipc/filesystem-auth-external-grant-native-realpath.test.ts b/src/main/ipc/filesystem-auth-external-grant-native-realpath.test.ts
new file mode 100644
index 000000000000..3aa4b2b527bd
--- /dev/null
+++ b/src/main/ipc/filesystem-auth-external-grant-native-realpath.test.ts
@@ -0,0 +1,90 @@
+import type * as NodeFs from 'node:fs'
+import type * as NodeFsPromises from 'node:fs/promises'
+import { join, relative, resolve } from 'node:path'
+import { describe, expect, it, vi } from 'vitest'
+import type { Store } from '../persistence'
+import type { FolderWorkspace } from '../../shared/folder-workspace-types'
+import type { ProjectGroup } from '../../shared/project-group-types'
+import type { Repo } from '../../shared/repo-types'
+import {
+  PATH_ACCESS_DENIED_MESSAGE,
+  authorizeExternalPath,
+  resolveAuthorizedPath
+} from './filesystem-auth'
+import { isDescendantOrEqual } from './filesystem-path-containment'
+
+const fsMocks = vi.hoisted(() => ({
+  jsRealpath: vi.fn((path: string) => path),
+  nativeRealpath: vi.fn((path: string) => path)
+}))
+
+vi.mock('node:fs', async (importOriginal) => {
+  const actual = await importOriginal<typeof NodeFs>()
+  return {
+    ...actual,
+    realpathSync: Object.assign(fsMocks.jsRealpath, { native: fsMocks.nativeRealpath })
+  }
+})
+vi.mock('node:fs/promises', async (importOriginal) => {
+  const actual = await importOriginal<typeof NodeFsPromises>()
+  return { ...actual, realpath: async (path: string) => fsMocks.nativeRealpath(path) }
+})
+vi.mock('../repo-worktrees', () => ({ listRepoWorktreeGraph: vi.fn(), isRepoRoot: vi.fn() }))
+
+// Why: a mapped (`net use`) or subst drive — the JS realpath keeps `X:\…`, the native one returns
+// the share or target path. Modelled with plain roots so the case runs on every platform.
+const mappedDrive = resolve('/mapped-drive')
+const shareRoot = resolve('/nas-share')
+
+function toShare(path: string): string {
+  return isDescendantOrEqual(path, mappedDrive)
+    ? join(shareRoot, relative(mappedDrive, path))
+    : path
+}
+fsMocks.nativeRealpath.mockImplementation(toShare)
+
+// oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: Authorization reads only these catalog and settings methods; an empty catalog leaves session grants as the only way in.
+const emptyStore = {
+  getRepos: (): Repo[] => [],
+  getProjectGroups: (): ProjectGroup[] => [],
+  getFolderWorkspaces: (): FolderWorkspace[] => [],
+  getSettings: (): { workspaceDir?: string } => ({})
+} as Store
+
+describe('external path grants on a drive the native realpath resolves elsewhere', () => {
+  it('lets a granted file on a mapped drive pass the read check', async () => {
+    const file = join(mappedDrive, 'docs', 'page-1.png')
+    authorizeExternalPath(file)
+
+    await expect(resolveAuthorizedPath(file, emptyStore)).resolves.toBe(
+      join(shareRoot, 'docs', 'page-1.png')
+    )
+  })
+
+  it('lets files under a granted mapped-drive folder pass the read check', async () => {
+    authorizeExternalPath(join(mappedDrive, 'notes'))
+
+    await expect(
+      resolveAuthorizedPath(join(mappedDrive, 'notes', 'todo.md'), emptyStore)
+    ).resolves.toBe(join(shareRoot, 'notes', 'todo.md'))
+  })
+
+  it('does not wait on the native realpath once the JS one has failed', () => {
+    fsMocks.jsRealpath.mockImplementationOnce(() => {
+      throw new Error('network path not found')
+    })
+    fsMocks.nativeRealpath.mockClear()
+
+    authorizeExternalPath(join(mappedDrive, 'offline', 'report.pdf'))
+
+    expect(fsMocks.nativeRealpath).not.toHaveBeenCalled()
+  })
+
+  it('does not extend a file grant to its siblings', async () => {
+    authorizeExternalPath(join(mappedDrive, 'private', 'shared.png'))
+
+    await expect(
+      resolveAuthorizedPath(join(mappedDrive, 'private', 'secret.txt'), emptyStore)
+    ).rejects.toThrow(PATH_ACCESS_DENIED_MESSAGE)
+  })
+})
diff --git a/src/main/ipc/filesystem-auth.ts b/src/main/ipc/filesystem-auth.ts
index 620baa9b5950..bf1989f4c1f8 100644
--- a/src/main/ipc/filesystem-auth.ts
+++ b/src/main/ipc/filesystem-auth.ts
@@ -41,6 +41,8 @@ export function authorizeExternalPath(targetPath: string): void {
   try {
     // Why: macOS canonicalizes /tmp to /private/tmp during read authorization.
     rememberAuthorizedExternalPath(realpathSync(resolvedTarget))
+    // Why: reads re-check the native realpath, which resolves a Windows mapped or subst drive that the JS one leaves as its letter. Same try, so an unreachable share is not waited on twice.
+    rememberAuthorizedExternalPath(resolve(realpathSync.native(resolvedTarget)))
   } catch {}
 }