fix: fix agent config path handling in generated deployment script

The generated agent deployment script now uses os.path.join and os.path.dirname(__file__) to construct the path to root_agent.yaml. This prevents issues where backslashes in Windows paths could be misinterpreted as Python escape sequences within the f-string, leading to syntax error

Close #4223

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 860236820

tests/unittests/cli/utils/test_cli_deploy.py

@@ -226,6 +226,19 @@ def test_get_service_option_by_adk_version(
   assert actual.rstrip() == expected.rstrip()
 
 
+def test_agent_engine_app_template_compiles_with_windows_paths() -> None:
+  """It should not emit invalid Python when paths contain `\\u` segments."""
+  rendered = cli_deploy._AGENT_ENGINE_APP_TEMPLATE.format(
+      is_config_agent=True,
+      agent_folder=r".\user_agent_tmp20260101_000000",
+      adk_app_object="root_agent",
+      adk_app_type="agent",
+      trace_to_cloud_option=False,
+      express_mode=False,
+  )
+  compile(rendered, "<agent_engine_app.py>", "exec")
+
+
 @pytest.mark.parametrize("include_requirements", [True, False])
 def test_to_agent_engine_happy_path(
     monkeypatch: pytest.MonkeyPatch,