diff --git a/src/new/services/placeholder_service.py b/src/new/services/placeholder_service.py
new file mode 100644
index 0000000..7c54872
--- /dev/null
+++ b/src/new/services/placeholder_service.py
@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+"""
+PlaceholderService —— 通用占位后端（用于尚未迁移的步骤）
+
+返回 ``{"status": "not_implemented", ...}``，main_router 据此在日志区
+输出友好提示；不抛异常、不阻塞 UI 线程。
+"""
+
+from __future__ import annotations
+
+from typing import Any, Dict
+
+
+def execute_placeholder(config: Dict[str, Any]) -> Dict[str, Any]:
+    """通用占位执行函数
+
+    Args:
+        config: 由 view.get_config() 序列化、再经 main_router 注入 work_dir 的字典
+
+    Returns:
+        标准结果字典 ``{status, output_path, message}``，其中 status="not_implemented"
+    """
+    step_id = config.get("step_id") or config.get("_step_id") or "unknown"
+    return {
+        "status": "not_implemented",
+        "output_path": None,
+        "message": f"not_implemented: [{step_id}] 端到端模块化尚未迁移此步骤；后续将按 step1 模式补全 view/service。",
+    }
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