fix(desktop): probe venv runtime health before trusting bootstrap marker

A broken/empty Windows launcher venv can see the source tree via PYTHONPATH
but lack PyYAML, so 'import hermes_cli' succeeds while the first real CLI
import dies — the desktop then trusts the bootstrap marker, spawns a dead
backend, and loops on 'gateway offline' (#52378).

- backend-probes.cjs: canImportHermesCli now runs 'import yaml; import
  hermes_cli.config' (extracted as hermesRuntimeImportProbe) and accepts an
  env override, so a dependency regression is caught without a real broken
  venv fixture.
- main.cjs: isBootstrapComplete() routes through new isActiveRuntimeUsable(),
  which requires the venv python to pass the runtime import probe (with
  ACTIVE_HERMES_ROOT on PYTHONPATH) — not just exist on disk.

Salvaged from PR #38179. The PR's install.ps1 reset/clean + autocrlf changes
and their tests are dropped: current main already preserves dirty checkouts
via stash (the data-loss-safe #38542 path) rather than the PR's older
reset-based Repair-ManagedCheckoutBeforeUpdate approach.

apps/desktop/electron/backend-probes.cjs

@@ -37,7 +37,18 @@ const { execFileSync } = require('node:child_process')
 const PROBE_TIMEOUT_MS = 5000
 
 /**
- * Return true iff `python -c "import hermes_cli"` exits 0.
+ * Return the Python snippet used to verify Hermes can import far enough to
+ * launch the CLI. Kept exported for tests so dependency regressions are
+ * caught without needing a real broken venv fixture.
+ *
+ * @returns {string}
+ */
+function hermesRuntimeImportProbe() {
+  return 'import yaml; import hermes_cli.config'
+}
+
+/**
+ * Return true iff the Hermes runtime import probe exits 0.
  *
  * Used to gate the "fallback to system Python with hermes_cli installed"
  * rung of resolveHermesBackend. Without this, a system Python 3.11-3.13
@@ -46,13 +57,20 @@ const PROBE_TIMEOUT_MS = 5000
  * site-packages -- and the resolver returns a backend that immediately
  * dies on spawn.
  *
+ * The probe intentionally imports hermes_cli.config, not just the top-level
+ * package: a broken/empty Windows launcher venv can still see the source tree
+ * through PYTHONPATH but lack PyYAML, then die on the first real CLI import.
+ *
  * @param {string} pythonPath - Absolute path to a python.exe / python.
+ * @param {object} [opts]
+ * @param {object} [opts.env] - Additional environment for the probe.
  * @returns {boolean}
  */
-function canImportHermesCli(pythonPath) {
+function canImportHermesCli(pythonPath, opts = {}) {
   if (!pythonPath) return false
   try {
-    execFileSync(pythonPath, ['-c', 'import hermes_cli'], {
+    execFileSync(pythonPath, ['-c', hermesRuntimeImportProbe()], {
+      env: { ...process.env, ...(opts.env || {}) },
       stdio: 'ignore',
       timeout: PROBE_TIMEOUT_MS,
       windowsHide: true
@@ -101,6 +119,7 @@ function verifyHermesCli(hermesCommand, opts = {}) {
 
 module.exports = {
   canImportHermesCli,
+  hermesRuntimeImportProbe,
   verifyHermesCli,
   PROBE_TIMEOUT_MS
 }

apps/desktop/electron/backend-probes.test.cjs

@@ -11,7 +11,7 @@ const fs = require('node:fs')
 const os = require('node:os')
 const path = require('node:path')
 
-const { canImportHermesCli, verifyHermesCli } = require('./backend-probes.cjs')
+const { canImportHermesCli, hermesRuntimeImportProbe, verifyHermesCli } = require('./backend-probes.cjs')
 
 // Resolve the host's own Node binary -- guaranteed to be on disk and
 // runnable. We use it as both a stand-in for "a python that doesn't
@@ -40,6 +40,12 @@ test('canImportHermesCli returns false when binary does not exist', () => {
   assert.equal(canImportHermesCli(ghost), false)
 })
 
+test('hermes runtime import probe checks config dependencies', () => {
+  const probe = hermesRuntimeImportProbe()
+  assert.match(probe, /\bimport yaml\b/)
+  assert.match(probe, /\bimport hermes_cli\.config\b/)
+})
+
 test('verifyHermesCli returns false when command is falsy', () => {
   assert.equal(verifyHermesCli(''), false)
   assert.equal(verifyHermesCli(null), false)

apps/desktop/electron/main.cjs

@@ -2608,6 +2608,24 @@ function readBootstrapMarker() {
   return readJson(BOOTSTRAP_COMPLETE_MARKER)
 }
 
+// Marker-independent: is the canonical install at ACTIVE_HERMES_ROOT actually
+// runnable right now? A complete CLI install (`install.sh --include-desktop`)
+// or a DMG launch over a prior CLI install satisfies this WITHOUT the desktop
+// ever having written the bootstrap marker -- so we must be able to recognise
+// "already installed" off the filesystem alone, not just the marker.
+function isActiveRuntimeUsable() {
+  const venvPython = getVenvPython(VENV_ROOT)
+  return (
+    isHermesSourceRoot(ACTIVE_HERMES_ROOT) &&
+    fileExists(venvPython) &&
+    canImportHermesCli(venvPython, {
+      env: {
+        PYTHONPATH: [ACTIVE_HERMES_ROOT, process.env.PYTHONPATH].filter(Boolean).join(path.delimiter)
+      }
+    })
+  )
+}
+
 function isBootstrapComplete() {
   const marker = readBootstrapMarker()
   if (!marker || typeof marker !== 'object') return false
@@ -2620,7 +2638,7 @@ function isBootstrapComplete() {
   // a runnable venv: an interrupted or split-home install can leave the marker
   // + checkout without a venv, and trusting that spawns a dead backend
   // ("gateway offline") instead of re-running bootstrap to repair it.
-  return isHermesSourceRoot(ACTIVE_HERMES_ROOT) && fileExists(getVenvPython(VENV_ROOT))
+  return isActiveRuntimeUsable()
 }
 
 function writeBootstrapMarker(payload) {