fix(update): also defer the missing-binary CUA install on Windows

Follow-up to the salvaged #94296: the two guards covered the repair and
confirmed-update branches, but when cua-driver is enabled yet not
installed at all, control still reached _run_cua_driver_installer() and
an automatic 'hermes update' would launch the interactive install.ps1
anyway. Add the same defer before the installer run, keep POSIX
behavior unchanged, and give the confirmed-update message a natural
fallback when latest_version is unknown.

hermes_cli/tools_config.py

@@ -1190,12 +1190,19 @@ def install_cua_driver(
             return True
         if _state is not None and _state.get("update_available"):
             if is_windows and require_confirmed_update:
-                _latest = _state.get("latest_version") or "a newer version"
-                _print_info(
-                    f"    {driver_cmd} {_latest} is available; keeping the "
-                    "installed version because its Windows installer may "
-                    "require interactive consent."
-                )
+                _latest = _state.get("latest_version")
+                if _latest:
+                    _print_info(
+                        f"    {driver_cmd} {_latest} is available; keeping the "
+                        "installed version because its Windows installer may "
+                        "require interactive consent."
+                    )
+                else:
+                    _print_info(
+                        f"    A newer {driver_cmd} release is available; "
+                        "keeping the installed version because its Windows "
+                        "installer may require interactive consent."
+                    )
                 _print_info(
                     "    Update it from an interactive terminal with: "
                     "hermes computer-use install --upgrade"
@@ -1214,6 +1221,22 @@ def install_cua_driver(
             if _re.fullmatch(r"\d+(\.\d+)*", _latest):
                 confirmed_version = _latest
 
+    if is_windows and require_confirmed_update and not binary:
+        # Missing-binary path (driver enabled in config but never installed,
+        # or wiped by a failed install). Same rule as the repair and
+        # confirmed-update branches above: an automatic Windows update must
+        # never launch install.ps1, which can demand console/UAC consent the
+        # hidden updater cannot provide (#87703).
+        _print_info(
+            "    cua-driver is not installed; automatic Windows updates "
+            "cannot safely run its interactive installer."
+        )
+        _print_info(
+            "    Install it from an interactive terminal with: "
+            "hermes computer-use install --upgrade"
+        )
+        return False
+
     if binary:
         # Show before/after version when we have a baseline. Best-effort.
         try:

tests/hermes_cli/test_install_cua_driver.py

@@ -440,7 +440,8 @@ class TestRequireConfirmedUpdate:
     still reinstall when the check can't answer.
     """
 
-    def _install(self, check_state, require_confirmed, contract_status=None):
+    def _install(self, check_state, require_confirmed, contract_status=None,
+                 binary_missing=False):
         """Drive ``install_cua_driver`` on the host, whatever it is.
 
         The old signature took a ``system`` string and faked
@@ -454,11 +455,15 @@ class TestRequireConfirmedUpdate:
 
         from hermes_cli import tools_config
 
+        _which_names = {"curl", "powershell"}
+        if not binary_missing:
+            _which_names.add("cua-driver")
         with patch.object(tools_config.shutil, "which",
                           side_effect=lambda n: "/x/" + n
-                          if n in {"cua-driver", "curl", "powershell"} else None), \
+                          if n in _which_names else None), \
              patch.object(tools_config, "_resolved_cua_driver_cmd",
-                          return_value="/x/cua-driver"), \
+                          return_value=None if binary_missing
+                          else "/x/cua-driver"), \
              patch.object(tools_config, "_cua_install_target_writable",
                           return_value=True), \
              patch.object(
@@ -546,6 +551,38 @@ class TestRequireConfirmedUpdate:
             for call in info.call_args_list
         )
 
+    @pytest.mark.windows_only
+    def test_windows_missing_binary_defers_interactive_install(self):
+        """Driver enabled but never installed (or wiped by a failed install):
+        the automatic update must not launch install.ps1 either — this path
+        reached the installer before the top-level guard (#94296 review)."""
+        ok, runner, info = self._install(
+            None,
+            require_confirmed=True,
+            binary_missing=True,
+        )
+
+        assert ok is False
+        runner.assert_not_called()
+        assert any(
+            "computer-use install --upgrade" in call.args[0]
+            for call in info.call_args_list
+        )
+
+    @pytest.mark.skipif(
+        sys.platform == "win32",
+        reason="POSIX installers are non-interactive; missing binary installs",
+    )
+    def test_posix_missing_binary_still_installs(self):
+        ok, runner, _ = self._install(
+            None,
+            require_confirmed=True,
+            binary_missing=True,
+        )
+
+        assert ok is True
+        runner.assert_called_once()
+
     def test_up_to_date_short_circuits(self):
         state = {"current_version": "0.6.0", "latest_version": "0.6.0",
                  "update_available": False}