refactor: unify host agent runtime access

tests/test_architecture_dependencies.py

@@ -1156,6 +1156,27 @@ def test_agent_application_facade_does_not_import_agent_implementation():
     } == set()
 
 
+def test_host_consumers_get_agent_manager_through_application_facade():
+    """宿主消费者不得绕过 Application 门面直接定位 Agent manager。"""
+    forbidden = {"get_agent_manager", "get_running_agent_manager"}
+    violations: dict[str, set[str]] = {}
+    for module_name, path in _discover_modules().items():
+        if module_name.startswith(("app.agent", "app.startup")):
+            continue
+        tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
+        imported = {
+            alias.name
+            for node in ast.walk(tree)
+            if isinstance(node, ast.ImportFrom)
+            and node.module == "app.agent.runtime_loader"
+            for alias in node.names
+            if alias.name in forbidden
+        }
+        if imported:
+            violations[module_name] = imported
+    assert violations == {}
+
+
 def test_agent_tools_do_not_import_entrypoint_internals():
     """Agent 工具不得穿透导入 HTTP 端点、调度器与命令注册表内部实现。