refactor ai_auto_response into xiaoniu group bot

plugins/ai_auto_response/persona_engine.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Dict
+
+
+class PersonaEngine:
+    def __init__(self, plugin_path: str, config: Dict):
+        self.plugin_path = Path(plugin_path)
+        self.config = config or {}
+        self.persona_text = self._load_persona()
+
+    def build_system_prompt(self) -> str:
+        name = self.config.get("name", "小牛")
+        style = self.config.get("style", "")
+        familiarity = self.config.get("familiarity_hint", "")
+        max_sentences = self.config.get("max_reply_sentences", 3)
+        return (
+            f"{self.persona_text}\n\n"
+            f"补充约束：\n"
+            f"- 你当前对外名称固定为{name}\n"
+            f"- 整体风格：{style}\n"
+            f"- 熟悉感边界：{familiarity}\n"
+            f"- 一般最多输出{max_sentences}句\n"
+            f"- 优先根据场景决定是答疑、接话还是不说话\n"
+        )
+
+    def _load_persona(self) -> str:
+        persona_file = self.config.get("persona_file", "persona/xiaoniu.txt")
+        persona_path = self.plugin_path / persona_file
+        if persona_path.exists():
+            return persona_path.read_text(encoding="utf-8").strip()
+        return "你叫小牛，是一个自然、靠谱、会看场合的群聊成员。"