feat(M2): Web AI 控制台——工具页新增子分栏：模型/Key/设备前端可配置（app_meta 存储，key 打码回显），指令执行 + 步骤流轮询（含截图缩略）+ 回答展示；Agent 加 on_step 回调、后台线程单实例运行

mcp_agent/agent.py

@@ -39,6 +39,7 @@ class Agent:
         self.tools_schema = []      # OpenAI function schema
         self._tool_exec = {}        # name -> callable
         self.messages = []
+        self.on_step = None         # 可选回调 fn(step_dict)，web 展示进度用
 
     # ---------- MCP 工具桥 ----------
     async def _load_tools(self):
@@ -93,12 +94,22 @@ class Agent:
         except Exception as e:
             return {"ok": False, "error": f"工具执行失败: {e}"}, None
         # de_screenshot：图像分离（作为 image_url 追加给模型看）
+        image_b64 = None
         if name == "de_screenshot" and isinstance(data, dict) and data.get("ok"):
             img = (data.get("data") or {}).get("image") or {}
             if img.get("data"):
                 text_result = {k: v for k, v in (data.get("data") or {}).items()
                                if k != "image"}
-                return text_result, img["data"]
+                image_b64 = img["data"]
+        if self.on_step:
+            try:
+                self.on_step({"tool": name, "args": args,
+                              "result": text_result if image_b64 else data,
+                              "image_b64": image_b64})
+            except Exception:
+                pass
+        if image_b64:
+            return text_result, image_b64
         return data, None
 
     # ---------- 主循环 ----------