Update session.py

session.py

@@ -31,6 +31,13 @@ class Session:
         # history
         self.chat_history: List[Dict[str, str]] = []
 
+        self.created_at: datetime = datetime.now()
+        self.last_activity: datetime = datetime.now()
+
+    def update_activity(self):
+        """Update last activity timestamp"""
+        self.last_activity = datetime.now()
+
     # -------- helper ----------
     def add_turn(self, role: str, content: str):
         self.chat_history.append({"role": role, "content": content})
@@ -66,5 +73,20 @@ class SessionStore:
     def __contains__(self, sid: str) -> bool:
         return self.get_session(sid) is not None
 
+    def cleanup_expired_sessions(self, timeout_minutes: int = 30):
+        """Remove expired sessions"""
+        with self._lock:
+            now = datetime.now()
+            expired = []
+            for sid, session in self._sessions.items():
+                if (now - session.last_activity).total_seconds() > timeout_minutes * 60:
+                    expired.append(sid)
+            
+            for sid in expired:
+                del self._sessions[sid]
+                log(f"🗑️ Expired session removed: {sid[:8]}...")
+            
+            if expired:
+                log(f"📊 Active sessions: {len(self._sessions)}")
 
 session_store = SessionStore()