fix(desktop): read HERMES_HOME from the Windows registry when env is stale

apps/desktop/electron/main.cjs

@@ -39,6 +39,7 @@ const { waitForDashboardPort } = require('./backend-ready.cjs')
 const { serializeJsonBody, setJsonRequestHeaders } = require('./oauth-net-request.cjs')
 const { fetchMarketplaceThemes, searchMarketplaceThemes } = require('./vscode-marketplace.cjs')
 const { buildDesktopBackendEnv } = require('./backend-env.cjs')
+const { readWindowsUserEnvVar } = require('./windows-user-env.cjs')
 const { readDirForIpc } = require('./fs-read-dir.cjs')
 const { gitRootForIpc } = require('./git-root.cjs')
 const { worktreesForIpc } = require('./git-worktrees.cjs')
@@ -242,6 +243,16 @@ if (INSTALL_STAMP) {
 function resolveHermesHome() {
   if (process.env.HERMES_HOME) return path.resolve(process.env.HERMES_HOME)
   if (USER_DATA_OVERRIDE) return path.join(path.resolve(USER_DATA_OVERRIDE), 'hermes-home')
+  if (IS_WINDOWS) {
+    // A GUI app launched from Explorer inherits the environment block captured
+    // at login, so a HERMES_HOME set via `setx` AFTER login is invisible in
+    // process.env even though the CLI (a fresh shell) sees it. Without this the
+    // backend silently falls back to %LOCALAPPDATA%\hermes and reports "No
+    // inference provider configured" despite a valid configured home (#45471).
+    // Consult the live User-scoped registry value before the default below.
+    const fromRegistry = readWindowsUserEnvVar('HERMES_HOME')
+    if (fromRegistry) return path.resolve(fromRegistry)
+  }
   if (IS_WINDOWS && process.env.LOCALAPPDATA) {
     const localappdata = path.join(process.env.LOCALAPPDATA, 'hermes')
     const legacy = path.join(app.getPath('home'), '.hermes')

apps/desktop/electron/windows-user-env.cjs

@@ -0,0 +1,76 @@
+// windows-user-env.cjs
+//
+// Read a User-scoped environment variable straight from the Windows registry
+// (HKCU\Environment).
+//
+// A GUI app launched from Explorer inherits the environment block captured at
+// login, so a variable set via `setx` AFTER login is invisible in process.env
+// even though a fresh shell — and the Hermes CLI — sees it immediately. The
+// desktop's HERMES_HOME resolution relies on process.env, so that stale-snapshot
+// gap silently sends the backend to the default %LOCALAPPDATA%\hermes. Reading
+// the live registry value closes the gap. See #45471.
+
+const { execFileSync } = require('node:child_process')
+
+// Parse the output of `reg query HKCU\Environment /v <name>`, which looks like:
+//
+//   HKEY_CURRENT_USER\Environment
+//       HERMES_HOME    REG_SZ    F:\Hermes\data
+//
+// Returns the raw value string (spaces inside the value preserved), or null when
+// the requested value line isn't present.
+function parseRegQueryValue(stdout, name) {
+  if (!stdout || !name) return null
+  const typePattern =
+    /^(\S+)\s+(?:REG_SZ|REG_EXPAND_SZ|REG_MULTI_SZ|REG_DWORD|REG_QWORD|REG_BINARY|REG_NONE)\s+(.*)$/
+  for (const rawLine of String(stdout).split(/\r?\n/)) {
+    const line = rawLine.trim()
+    const match = line.match(typePattern)
+    if (match && match[1].toLowerCase() === name.toLowerCase()) {
+      return match[2]
+    }
+  }
+  return null
+}
+
+// Expand %VAR% references against an env map. REG_EXPAND_SZ values store
+// unexpanded references; plain REG_SZ paths have none, so this is a no-op for
+// the common F:\... case. Unknown references are left verbatim.
+function expandWindowsEnvRefs(value, env = process.env) {
+  if (!value) return value
+  return value.replace(/%([^%]+)%/g, (whole, name) => {
+    const key = Object.keys(env).find(k => k.toUpperCase() === String(name).toUpperCase())
+    return key != null && env[key] != null ? env[key] : whole
+  })
+}
+
+// Read a User-scoped env var from HKCU\Environment. Windows-only: returns null
+// off-Windows (without spawning), on any spawn error, when `reg` exits non-zero
+// (the value doesn't exist), or when the value is empty.
+function readWindowsUserEnvVar(
+  name,
+  { platform = process.platform, env = process.env, exec = execFileSync } = {}
+) {
+  if (platform !== 'win32' || !name) return null
+  let stdout
+  try {
+    stdout = exec('reg', ['query', 'HKCU\\Environment', '/v', name], {
+      encoding: 'utf8',
+      windowsHide: true,
+      timeout: 5000
+    })
+  } catch {
+    // `reg` missing, or value absent (reg exits 1) — caller falls back.
+    return null
+  }
+  const raw = parseRegQueryValue(stdout, name)
+  if (raw == null) return null
+  const expanded = expandWindowsEnvRefs(raw, env).trim()
+  return expanded || null
+}
+
+module.exports = {
+  expandWindowsEnvRefs,
+  parseRegQueryValue,
+  readWindowsUserEnvVar
+}

apps/desktop/electron/windows-user-env.test.cjs

@@ -0,0 +1,90 @@
+const assert = require('node:assert/strict')
+const { test } = require('node:test')
+
+const {
+  expandWindowsEnvRefs,
+  parseRegQueryValue,
+  readWindowsUserEnvVar
+} = require('./windows-user-env.cjs')
+
+// ── parseRegQueryValue ─────────────────────────────────────────────────────
+
+test('parseRegQueryValue extracts a REG_SZ value', () => {
+  const out = [
+    '',
+    'HKEY_CURRENT_USER\\Environment',
+    '    HERMES_HOME    REG_SZ    F:\\Hermes\\data',
+    ''
+  ].join('\r\n')
+  assert.equal(parseRegQueryValue(out, 'HERMES_HOME'), 'F:\\Hermes\\data')
+})
+
+test('parseRegQueryValue matches the name case-insensitively', () => {
+  const out = 'HKEY_CURRENT_USER\\Environment\r\n    Hermes_Home    REG_EXPAND_SZ    %USERPROFILE%\\h\r\n'
+  assert.equal(parseRegQueryValue(out, 'HERMES_HOME'), '%USERPROFILE%\\h')
+})
+
+test('parseRegQueryValue preserves spaces inside the value', () => {
+  const out = '    HERMES_HOME    REG_SZ    C:\\Program Files\\Hermes\r\n'
+  assert.equal(parseRegQueryValue(out, 'HERMES_HOME'), 'C:\\Program Files\\Hermes')
+})
+
+test('parseRegQueryValue returns null when the value line is absent', () => {
+  const out = 'HKEY_CURRENT_USER\\Environment\r\n    Path    REG_SZ    C:\\x\r\n'
+  assert.equal(parseRegQueryValue(out, 'HERMES_HOME'), null)
+  assert.equal(parseRegQueryValue('', 'HERMES_HOME'), null)
+  assert.equal(parseRegQueryValue('garbage', 'HERMES_HOME'), null)
+})
+
+// ── expandWindowsEnvRefs ───────────────────────────────────────────────────
+
+test('expandWindowsEnvRefs expands %VAR% case-insensitively', () => {
+  assert.equal(
+    expandWindowsEnvRefs('%UserProfile%\\h', { USERPROFILE: 'C:\\Users\\jeff' }),
+    'C:\\Users\\jeff\\h'
+  )
+})
+
+test('expandWindowsEnvRefs leaves literal paths and unknown refs intact', () => {
+  assert.equal(expandWindowsEnvRefs('F:\\Hermes\\data', {}), 'F:\\Hermes\\data')
+  assert.equal(expandWindowsEnvRefs('%NOPE%\\x', {}), '%NOPE%\\x')
+})
+
+// ── readWindowsUserEnvVar ──────────────────────────────────────────────────
+
+test('readWindowsUserEnvVar returns null off Windows without spawning', () => {
+  let spawned = false
+  const exec = () => {
+    spawned = true
+    return ''
+  }
+  assert.equal(readWindowsUserEnvVar('HERMES_HOME', { platform: 'linux', exec }), null)
+  assert.equal(spawned, false)
+})
+
+test('readWindowsUserEnvVar queries HKCU\\Environment and expands the value', () => {
+  const calls = []
+  const exec = (cmd, args) => {
+    calls.push([cmd, args])
+    return 'HKEY_CURRENT_USER\\Environment\r\n    HERMES_HOME    REG_EXPAND_SZ    %DRIVE%\\Hermes\r\n'
+  }
+  const value = readWindowsUserEnvVar('HERMES_HOME', {
+    platform: 'win32',
+    env: { DRIVE: 'F:' },
+    exec
+  })
+  assert.equal(value, 'F:\\Hermes')
+  assert.deepEqual(calls, [['reg', ['query', 'HKCU\\Environment', '/v', 'HERMES_HOME']]])
+})
+
+test('readWindowsUserEnvVar returns null when reg exits non-zero (value missing)', () => {
+  const exec = () => {
+    throw new Error('reg exited 1')
+  }
+  assert.equal(readWindowsUserEnvVar('HERMES_HOME', { platform: 'win32', exec }), null)
+})
+
+test('readWindowsUserEnvVar returns null for an empty value', () => {
+  const exec = () => '    HERMES_HOME    REG_SZ    \r\n'
+  assert.equal(readWindowsUserEnvVar('HERMES_HOME', { platform: 'win32', exec }), null)
+})

apps/desktop/package.json

@@ -36,7 +36,7 @@
     "test:desktop:nsis": "node scripts/test-desktop.mjs nsis",
     "test:desktop:existing": "node scripts/test-desktop.mjs existing",
     "test:desktop:fresh": "node scripts/test-desktop.mjs fresh",
-    "test:desktop:platforms": "node --test electron/bootstrap-platform.test.cjs electron/hardening.test.cjs electron/backend-env.test.cjs electron/backend-probes.test.cjs electron/bootstrap-runner.test.cjs electron/connection-config.test.cjs electron/dashboard-token.test.cjs electron/gateway-ws-probe.test.cjs electron/oauth-net-request.test.cjs electron/desktop-uninstall.test.cjs electron/session-windows.test.cjs electron/workspace-cwd.test.cjs electron/fs-read-dir.test.cjs electron/git-root.test.cjs electron/windows-child-process.test.cjs electron/update-remote.test.cjs",
+    "test:desktop:platforms": "node --test electron/bootstrap-platform.test.cjs electron/hardening.test.cjs electron/backend-env.test.cjs electron/backend-probes.test.cjs electron/bootstrap-runner.test.cjs electron/connection-config.test.cjs electron/dashboard-token.test.cjs electron/gateway-ws-probe.test.cjs electron/oauth-net-request.test.cjs electron/desktop-uninstall.test.cjs electron/session-windows.test.cjs electron/workspace-cwd.test.cjs electron/fs-read-dir.test.cjs electron/git-root.test.cjs electron/windows-child-process.test.cjs electron/update-remote.test.cjs electron/windows-user-env.test.cjs",
     "typecheck": "tsc -p . --noEmit",
     "lint": "eslint src/ electron/",
     "lint:fix": "eslint src/ electron/ --fix",