fix(windows): probe fnm's real default alias dir for Node fallback (#11359)

* fix(windows): probe fnm's real default alias dir for Node fallback

On Windows, fnm stores the default alias under FNM_DIR, else
%APPDATA%\fnm (legacy ~\.fnm), and node.exe sits directly in
aliases\default with no bin subdir. Probe those dirs and append them to
PATH so fnm's default only backfills a missing Node instead of shadowing
an inherited one.

Fixes #11356

Co-authored-by: niceSprite <16523864+iFwu@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

* test: keep onTestFinished callbacks returning void

---------

Co-authored-by: Neil <neil@stably.ai>
Co-authored-by: Claude <noreply@anthropic.com>

src/cli/handlers/account.ts

@@ -9,6 +9,7 @@ import { stripElectronRunAsNode } from '../runtime/orca-app-executable'
 import { rejectRemoteSelectionFlags } from '../remote-selection-flag-rejection'
 import { buildWslExecArgs, buildWslLoginShellCommand } from '../../shared/wsl-login-shell-command'
 import { quotePosixShell } from '../../shared/shell-argument-quoting'
+import { isWindowsFnmDefaultAliasDir } from '../../shared/fnm-default-alias-dirs'
 import {
   getVersionManagerBinPaths,
   resolveCliCommand,
@@ -55,7 +56,9 @@ function addAgentNodePaths(env: NodeJS.ProcessEnv): NodeJS.ProcessEnv {
   const existing = new Set(currentEntries)
   const missing = getVersionManagerBinPaths().filter((entry) => !existing.has(entry))
   if (missing.length > 0) {
-    env[pathKey] = [...missing, ...currentEntries].join(delimiter)
+    const append = missing.filter(isWindowsFnmDefaultAliasDir)
+    const prepend = missing.filter((entry) => !append.includes(entry))
+    env[pathKey] = [...prepend, ...currentEntries, ...append].join(delimiter)
   }
   return env
 }

src/main/codex-cli/command.test.ts

@@ -1,7 +1,7 @@
 import { chmodSync, mkdtempSync, mkdirSync, rmSync, writeFileSync } from 'node:fs'
 import { tmpdir } from 'node:os'
 import { delimiter, dirname, join } from 'node:path'
-import { afterEach, describe, expect, it, onTestFinished } from 'vitest'
+import { afterEach, describe, expect, it, onTestFinished, vi } from 'vitest'
 import {
   getVersionManagerBinPaths,
   withCliRuntimeOnPath,
@@ -319,6 +319,33 @@ describe('getVersionManagerBinPaths', () => {
     expect(paths).toContain(join(root, '.local', 'bin'))
     expect(paths).toContain(join(root, 'AppData', 'Roaming', 'npm'))
   })
+
+  it('uses the Windows fnm default alias layout, honoring FNM_DIR (stablyai/orca#11356)', () => {
+    const root = makeCommandFixture('orca-vm-paths-')
+    const appDataAlias = join(root, 'AppData', 'Roaming', 'fnm', 'aliases', 'default')
+    vi.stubEnv('FNM_DIR', '')
+    vi.stubEnv('APPDATA', '')
+    onTestFinished(() => {
+      vi.unstubAllEnvs()
+    })
+
+    const paths = getVersionManagerBinPaths({ platform: 'win32', homePath: root })
+    expect(paths).toContain(appDataAlias)
+    expect(paths).not.toContain(join(root, '.fnm', 'aliases', 'default', 'bin'))
+
+    const redirectedAppData = join(root, 'redirected')
+    const redirectedAlias = join(redirectedAppData, 'fnm', 'aliases', 'default')
+    vi.stubEnv('APPDATA', redirectedAppData)
+    expect(getVersionManagerBinPaths({ platform: 'win32', homePath: root })).toContain(
+      redirectedAlias
+    )
+
+    const fnmDir = join(root, 'custom-fnm')
+    vi.stubEnv('FNM_DIR', fnmDir)
+    const overridden = getVersionManagerBinPaths({ platform: 'win32', homePath: root })
+    expect(overridden).toContain(join(fnmDir, 'aliases', 'default'))
+    expect(overridden).not.toContain(redirectedAlias)
+  })
 })
 
 describe('withCliRuntimeOnPath', () => {

src/main/startup/configure-process.test.ts

@@ -1,7 +1,7 @@
 import { existsSync, mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs'
 import { homedir, tmpdir } from 'node:os'
 import { join } from 'node:path'
-import { afterEach, describe, expect, it, vi } from 'vitest'
+import { afterEach, describe, expect, it, onTestFinished, vi } from 'vitest'
 
 vi.mock('electron', () => {
   const paths = new Map<string, string>([['appData', '/tmp/app-data']])
@@ -224,6 +224,10 @@ describe('patchPackagedProcessPath', () => {
 
     setPlatform('win32')
     Object.defineProperty(app, 'isPackaged', { configurable: true, value: true })
+    vi.stubEnv('FNM_DIR', 'C:\\fnm')
+    onTestFinished(() => {
+      vi.unstubAllEnvs()
+    })
     const pathDelimiter = process.platform === 'win32' ? ';' : ':'
     process.env.PATH = `C:\\Windows\\System32${pathDelimiter}C:\\Windows`
 
@@ -233,6 +237,9 @@ describe('patchPackagedProcessPath', () => {
     const userLocalBin = join(homedir(), '.local', 'bin')
     expect(segments).toContain(userLocalBin)
     expect(segments.indexOf(userLocalBin)).toBeLessThan(segments.indexOf('C:\\Windows\\System32'))
+    // #11356: fnm's default Node only backfills; it must not shadow an inherited system Node.
+    const fnmAlias = join('C:\\fnm', 'aliases', 'default')
+    expect(segments.indexOf(fnmAlias)).toBeGreaterThan(segments.indexOf('C:\\Windows'))
   })
 })
 

src/main/startup/configure-process.ts

@@ -4,6 +4,7 @@ import { mkdirSync } from 'node:fs'
 import { homedir } from 'node:os'
 import { join, resolve } from 'node:path'
 import { getVersionManagerBinPaths } from '../codex-cli/command'
+import { isWindowsFnmDefaultAliasDir } from '../../shared/fnm-default-alias-dirs'
 import { getMainE2EConfig } from '../e2e-config'
 import { DISABLED_CHROMIUM_FEATURES } from './disabled-chromium-features'
 import { readHttp1CompatibilityMarker } from './http1-compatibility-marker'
@@ -158,7 +159,13 @@ export function patchPackagedProcessPath(): void {
   }
 
   // env-node shebangs require runtime shims; exclude generic user bins so arbitrary wrappers cannot shadow system tools.
-  prependPaths.push(...getVersionManagerBinPaths().filter((path) => !isGenericUserBinDir(path)))
+  for (const path of getVersionManagerBinPaths()) {
+    if (isWindowsFnmDefaultAliasDir(path)) {
+      appendPaths.push(path)
+    } else if (!isGenericUserBinDir(path)) {
+      prependPaths.push(path)
+    }
+  }
 
   const pathKey = process.platform === 'win32' && process.env.Path !== undefined ? 'Path' : 'PATH'
   const currentPath = process.env[pathKey] ?? ''

src/shared/fnm-default-alias-dirs.ts

@@ -0,0 +1,24 @@
+import { homedir } from 'node:os'
+import { join } from 'node:path'
+
+/** fnm's `default` alias dir. Windows: FNM_DIR, else %APPDATA%\fnm, else legacy ~\.fnm; node.exe has no bin subdir (#11356). */
+export function getFnmDefaultAliasDirectories(
+  platform: NodeJS.Platform,
+  homePath: string
+): string[] {
+  if (platform !== 'win32') {
+    return [join(homePath, '.fnm', 'aliases', 'default', 'bin')]
+  }
+  const fnmDir = process.env.FNM_DIR
+  const appData = process.env.APPDATA || join(homePath, 'AppData', 'Roaming')
+  const baseDirs = fnmDir ? [fnmDir] : [join(appData, 'fnm'), join(homePath, '.fnm')]
+  return baseDirs.map((baseDir) => join(baseDir, 'aliases', 'default'))
+}
+
+/** Windows fnm default only backfills a missing node; leading PATH would shadow an inherited system/nvm-windows/`fnm use` Node. */
+export function isWindowsFnmDefaultAliasDir(path: string): boolean {
+  return (
+    process.platform === 'win32' &&
+    getFnmDefaultAliasDirectories(process.platform, homedir()).includes(path)
+  )
+}

src/shared/node-cli-command-resolution.ts

@@ -2,6 +2,7 @@ import { accessSync, constants, existsSync, readFileSync, readdirSync, statSync
 import { homedir } from 'node:os'
 import { delimiter, dirname, isAbsolute, join } from 'node:path'
 import { firstWindowsPathEnvKey, isNativeExecutable } from './cli-runtime-pairing-inputs'
+import { getFnmDefaultAliasDirectories } from './fnm-default-alias-dirs'
 import { getSystemCliInstallDirectories } from './system-cli-install-dirs'
 
 type ResolveCommandOptions = {
@@ -93,7 +94,7 @@ function getBaseVersionManagerDirectories(platform: NodeJS.Platform, homePath: s
   const directories = [
     join(homePath, '.volta', 'bin'),
     join(homePath, '.asdf', 'shims'),
-    join(homePath, '.fnm', 'aliases', 'default', 'bin'),
+    ...getFnmDefaultAliasDirectories(platform, homePath),
     join(homePath, '.local', 'share', 'mise', 'shims')
   ]