feat: 新增核心服务模块

- mqtt_service: MQTT 订阅服务，对接 ai_edge 告警和心跳
- notification_service: WebSocket 实时推送服务
- device_service: 边缘设备心跳管理和离线检测

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/services/notification_service.py

@@ -0,0 +1,145 @@
+"""
+通知服务
+支持 WebSocket 实时推送
+"""
+import asyncio
+import json
+from datetime import datetime
+from typing import Dict, Any, List, Set
+from fastapi import WebSocket
+
+from app.utils.logger import logger
+
+
+class ConnectionManager:
+    """WebSocket 连接管理器"""
+
+    def __init__(self):
+        # 活跃连接
+        self._active_connections: Set[WebSocket] = set()
+
+    async def connect(self, websocket: WebSocket):
+        """接受新连接"""
+        await websocket.accept()
+        self._active_connections.add(websocket)
+        logger.info(f"WebSocket 客户端已连接, 当前连接数: {len(self._active_connections)}")
+
+    def disconnect(self, websocket: WebSocket):
+        """断开连接"""
+        self._active_connections.discard(websocket)
+        logger.info(f"WebSocket 客户端已断开, 当前连接数: {len(self._active_connections)}")
+
+    async def broadcast(self, message: Dict[str, Any]):
+        """广播消息到所有客户端"""
+        if not self._active_connections:
+            return
+
+        message_json = json.dumps(message, ensure_ascii=False, default=str)
+        disconnected = set()
+
+        for connection in self._active_connections:
+            try:
+                await connection.send_text(message_json)
+            except Exception as e:
+                logger.warning(f"WebSocket 发送失败: {e}")
+                disconnected.add(connection)
+
+        # 移除断开的连接
+        self._active_connections -= disconnected
+
+    async def send_personal(self, websocket: WebSocket, message: Dict[str, Any]):
+        """发送消息到指定客户端"""
+        try:
+            message_json = json.dumps(message, ensure_ascii=False, default=str)
+            await websocket.send_text(message_json)
+        except Exception as e:
+            logger.warning(f"WebSocket 发送失败: {e}")
+
+    @property
+    def connection_count(self) -> int:
+        return len(self._active_connections)
+
+
+class NotificationService:
+    """通知服务"""
+
+    def __init__(self):
+        self._manager = ConnectionManager()
+        self._loop: asyncio.AbstractEventLoop = None
+
+    @property
+    def manager(self) -> ConnectionManager:
+        return self._manager
+
+    def set_event_loop(self, loop: asyncio.AbstractEventLoop):
+        """设置事件循环（用于从同步代码调用异步方法）"""
+        self._loop = loop
+
+    async def notify_new_alert(self, alert_data: Dict[str, Any]):
+        """通知新告警"""
+        message = {
+            "event": "new_alert",
+            "data": alert_data,
+            "timestamp": datetime.utcnow().isoformat(),
+        }
+        await self._manager.broadcast(message)
+        logger.debug(f"已广播新告警通知: {alert_data.get('alert_no', 'N/A')}")
+
+    async def notify_alert_updated(self, alert_data: Dict[str, Any]):
+        """通知告警更新"""
+        message = {
+            "event": "alert_updated",
+            "data": alert_data,
+            "timestamp": datetime.utcnow().isoformat(),
+        }
+        await self._manager.broadcast(message)
+
+    async def notify_device_status(self, device_data: Dict[str, Any]):
+        """通知设备状态变更"""
+        message = {
+            "event": "device_status",
+            "data": device_data,
+            "timestamp": datetime.utcnow().isoformat(),
+        }
+        await self._manager.broadcast(message)
+
+    async def notify_work_order(self, order_data: Dict[str, Any], event_type: str = "new"):
+        """通知工单事件"""
+        message = {
+            "event": f"work_order_{event_type}",
+            "data": order_data,
+            "timestamp": datetime.utcnow().isoformat(),
+        }
+        await self._manager.broadcast(message)
+
+    def notify_sync(self, event: str, data: Dict[str, Any]):
+        """同步方式通知（用于从 MQTT 回调等同步代码调用）"""
+        if self._loop is None:
+            logger.warning("事件循环未设置，无法发送通知")
+            return
+
+        message = {
+            "event": event,
+            "data": data,
+            "timestamp": datetime.utcnow().isoformat(),
+        }
+
+        async def _broadcast():
+            await self._manager.broadcast(message)
+
+        try:
+            asyncio.run_coroutine_threadsafe(_broadcast(), self._loop)
+        except Exception as e:
+            logger.error(f"同步通知失败: {e}")
+
+
+# 全局单例
+_notification_service = None
+
+
+def get_notification_service() -> NotificationService:
+    """获取通知服务单例"""
+    global _notification_service
+    if _notification_service is None:
+        _notification_service = NotificationService()
+    return _notification_service