首个可运行的版本

backend/app/websocket/manager.py

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+"""WebSocket 连接管理器"""
+
+import json
+from datetime import datetime, timezone
+from typing import Dict, Set
+
+from fastapi import WebSocket
+
+
+class ConnectionManager:
+    """管理所有 WebSocket 连接"""
+
+    def __init__(self):
+        # user_id -> set of WebSocket connections (一个用户可能有多个标签页)
+        self.active_connections: Dict[str, Set[WebSocket]] = {}
+
+    async def connect(self, websocket: WebSocket, user_id: str):
+        """接受新连接"""
+        await websocket.accept()
+        if user_id not in self.active_connections:
+            self.active_connections[user_id] = set()
+        self.active_connections[user_id].add(websocket)
+
+    def disconnect(self, websocket: WebSocket, user_id: str):
+        """断开连接"""
+        if user_id in self.active_connections:
+            self.active_connections[user_id].discard(websocket)
+            if not self.active_connections[user_id]:
+                del self.active_connections[user_id]
+
+    async def send_to_user(self, user_id: str, event_type: str, data: dict):
+        """向指定用户发送事件"""
+        if user_id not in self.active_connections:
+            return
+
+        message = json.dumps({
+            "type": event_type,
+            "data": data,
+            "timestamp": datetime.utcnow().isoformat(),
+        }, ensure_ascii=False, default=str)
+
+        disconnected = set()
+        for ws in self.active_connections[user_id]:
+            try:
+                await ws.send_text(message)
+            except Exception:
+                disconnected.add(ws)
+
+        # 清理断开的连接
+        for ws in disconnected:
+            self.active_connections[user_id].discard(ws)
+
+    async def broadcast_to_conversation(self, user_ids: list[str],
+                                         event_type: str, data: dict,
+                                         exclude_user: str | None = None):
+        """向会话中所有用户广播事件"""
+        for uid in user_ids:
+            if uid != exclude_user:
+                await self.send_to_user(uid, event_type, data)
+
+    async def broadcast(self, event_type: str, data: dict):
+        """向所有在线用户广播"""
+        for user_id in list(self.active_connections.keys()):
+            await self.send_to_user(user_id, event_type, data)
+
+    def is_online(self, user_id: str) -> bool:
+        """检查用户是否在线"""
+        return user_id in self.active_connections and len(self.active_connections[user_id]) > 0
+
+    def get_online_user_ids(self) -> list[str]:
+        """获取所有在线用户 ID"""
+        return list(self.active_connections.keys())
+
+
+# 全局单例
+manager = ConnectionManager()