feat: 增加 screen_id 参数以支持针对特定屏幕的工具执行，优化大屏控制逻辑

backend/app/tools.py

@@ -60,15 +60,15 @@ def _query_companies(args):
     }, ensure_ascii=False)
 
 
-def _control_display(args):
-    """大屏显示控制：切页 / 弹通知 / 媒体播放暂停（经 MQTT 广播到大屏）"""
+def _control_display(args, screen_id=""):
+    """大屏显示控制：切页 / 弹通知 / 媒体播放暂停（经 MQTT 按发起屏幕下发）"""
     from .mqtt import hub
     action = (args.get("action") or "").strip()
     target = (args.get("target") or "").strip()
     if action not in ("switch_page", "alert", "media_play", "media_pause"):
         return json.dumps({"error": f"不支持的 action: {action}"}, ensure_ascii=False)
     params = {"target": target} if target else {}
-    ok = hub.publish_command(action, params).get("published", False)
+    ok = hub.publish_command(action, params, screen_id=screen_id).get("published", False)
     return json.dumps({"ok": ok, "action": action, "target": target}, ensure_ascii=False)
 
 
@@ -125,15 +125,19 @@ def tool_schemas():
     ]
 
 
-def exec_tool(name: str, args: dict):
-    """执行工具 → 返回给 LLM 的字符串结果（JSON）"""
+def exec_tool(name: str, args: dict, screen_id: str = ""):
+    """执行工具 → 返回给 LLM 的字符串结果（JSON）。
+       控制类工具（control_display）按发起屏幕 screen_id 只下发到该屏。"""
     t = TOOLS.get(name)
     if not t:
         log.warning("tools: 未知工具 %s", name)
         return json.dumps({"error": f"未知工具: {name}"}, ensure_ascii=False)
     try:
-        result = t["fn"](args or {})
-        log.info("tools: 执行工具 %s args=%s", name, json.dumps(args, ensure_ascii=False))
+        if name == "control_display":
+            result = _control_display(args or {}, screen_id)
+        else:
+            result = t["fn"](args or {})
+        log.info("tools: 执行工具 %s args=%s screen=%s", name, json.dumps(args, ensure_ascii=False), screen_id or "all")
         log.info("tools:   结果 -> %s", _trunc(result, 1000))
         return result
     except Exception as e:  # noqa: BLE001