diff --git a/hermes_cli/main.py b/hermes_cli/main.py
index 034438255daf..dbabf547f26d 100644
--- a/hermes_cli/main.py
+++ b/hermes_cli/main.py
@@ -5733,7 +5733,14 @@ def cmd_gui(args: argparse.Namespace):
             print(f"✓ Desktop {build_label} is up to date (content stamp matches)")
         else:
             print("→ Installing desktop workspace dependencies...")
-            nixos_env = _nixos_build_env()
+            # Put the Hermes-managed Node on PATH so npm's child scripts (which
+            # shell out to bare `node`, e.g. electron-winstaller's
+            # select-7z-arch.js) resolve it even when the parent PATH is
+            # stripped — the desktop updater chain (Desktop → hermes-setup →
+            # hermes update) loses shell PATH customizations. Wrapping the
+            # NixOS build env keeps its PYTHON hint while restoring managed Node
+            # ahead of a bare PATH (same idiom as the `hermes update` path).
+            nixos_env = with_hermes_node_path(_nixos_build_env())
             install_result = _run_npm_install_deterministic(npm, PROJECT_ROOT, capture_output=False, env=nixos_env)
             if install_result.returncode != 0:
                 if not _electron_pkg_staged_missing_dist(PROJECT_ROOT):
@@ -10283,9 +10290,18 @@ def _cmd_update_impl(args, gateway_mode: bool):
             # covers a still-settling rebuild window the first wait didn't fully
             # catch — then surface the captured tail so the failure is
             # debuggable.
-            build_result = _run_logged_subprocess(_desktop_build_cmd, cwd=PROJECT_ROOT)
+            #
+            # Start the build subprocess with the Hermes-managed Node on PATH:
+            # when `hermes update` runs inside the desktop updater chain
+            # (Desktop → hermes-setup → hermes update), the shell PATH
+            # customizations are lost, so a bare-PATH child would fail with
+            # `node: not found` before cmd_gui can self-heal.
+            from hermes_constants import with_hermes_node_path
+
+            _build_env = with_hermes_node_path()
+            build_result = _run_logged_subprocess(_desktop_build_cmd, cwd=PROJECT_ROOT, env=_build_env)
             if build_result.returncode != 0:
-                build_result = _run_logged_subprocess(_desktop_build_cmd, cwd=PROJECT_ROOT)
+                build_result = _run_logged_subprocess(_desktop_build_cmd, cwd=PROJECT_ROOT, env=_build_env)
             if build_result.returncode != 0:
                 print("  ⚠ Desktop build failed (non-fatal; run `hermes desktop` to retry)")
                 tail = "\n".join((build_result.stdout or "").strip().splitlines()[-15:])
diff --git a/tests/hermes_cli/test_gui_command.py b/tests/hermes_cli/test_gui_command.py
index 6fcddcb9974b..b5fd1ab8d327 100644
--- a/tests/hermes_cli/test_gui_command.py
+++ b/tests/hermes_cli/test_gui_command.py
@@ -70,13 +70,59 @@ def test_gui_installs_packages_and_launches_desktop_app(tmp_path, monkeypatch):
         cli_main.cmd_gui(_ns())
 
     assert exc.value.code == 0
-    mock_install.assert_called_once_with("/usr/bin/npm", root, capture_output=False, env=None)
+    # The install now runs with a resolved env (managed-Node PATH), never a bare
+    # ``env=None`` that would leave npm's child scripts unable to find ``node``.
+    mock_install.assert_called_once()
+    assert mock_install.call_args.args == ("/usr/bin/npm", root)
+    assert mock_install.call_args.kwargs["capture_output"] is False
+    install_env = mock_install.call_args.kwargs["env"]
+    assert install_env is not None and "PATH" in install_env
     assert mock_run.call_args_list[0].args[0] == ["/usr/bin/npm", "run", "pack"]
     assert mock_run.call_args_list[0].kwargs["cwd"] == desktop_dir
     assert mock_run.call_args_list[1].args[0] == [str(packaged_exe)]
     assert mock_run.call_args_list[1].kwargs["cwd"] == desktop_dir
 
 
+def test_gui_install_env_prepends_managed_node_on_bare_path(tmp_path, monkeypatch):
+    """Regression: npm's child scripts (electron-winstaller's select-7z-arch.js)
+    shell out to bare ``node``. When Desktop is launched from the updater chain
+    the parent PATH is stripped, so the install env MUST carry the Hermes-managed
+    Node ahead of that bare PATH or the install dies with ``node: not found``.
+    """
+    import os
+
+    from hermes_constants import iter_hermes_node_dirs
+
+    root = _make_desktop_tree(tmp_path)
+    monkeypatch.setattr(cli_main, "PROJECT_ROOT", root)
+    _make_packaged_executable(root, monkeypatch, platform="win32")
+
+    # A managed Node tree on disk so with_hermes_node_path() actually prepends it.
+    home = tmp_path / "hermes-home"
+    (home / "node" / "bin").mkdir(parents=True)
+    monkeypatch.setenv("HERMES_HOME", str(home))
+    # Simulate the stripped PATH the desktop updater chain hands us.
+    monkeypatch.setenv("PATH", os.pathsep.join(["/usr/bin", "/bin"]))
+
+    install_ok = subprocess.CompletedProcess(["npm", "ci"], 0)
+    launch_ok = subprocess.CompletedProcess(["hermes"], 0)
+
+    with patch("hermes_cli.main._resolve_node_runtime_npm", return_value="/usr/bin/npm"), \
+         patch("hermes_cli.main._run_npm_install_deterministic", return_value=install_ok) as mock_install, \
+         patch("hermes_cli.main._desktop_build_needed", return_value=True), \
+         patch("hermes_cli.main._write_desktop_build_stamp"), \
+         patch("hermes_cli.main.subprocess.run", side_effect=[subprocess.CompletedProcess([], 0), launch_ok]), \
+         pytest.raises(SystemExit):
+        cli_main.cmd_gui(_ns(skip_build=False))
+
+    managed_dirs = [str(p) for p in iter_hermes_node_dirs() if p.is_dir()]
+    assert managed_dirs, "managed node tree not discovered"
+    install_env = mock_install.call_args.kwargs["env"]
+    path_parts = install_env["PATH"].split(os.pathsep)
+    assert path_parts[: len(managed_dirs)] == managed_dirs
+    assert "/usr/bin" in path_parts  # the bare updater PATH is preserved, just after managed Node
+
+
 def test_gui_forwards_desktop_environment_overrides(tmp_path, monkeypatch):
     root = _make_desktop_tree(tmp_path)
     hermes_root = tmp_path / "custom-hermes"