fix: graceful ctrl+c shutdown and await session-end memory writes

src/gateway/server.ts

@@ -564,11 +564,14 @@ export class GatewayServer {
       }
     }
 
-    // Close all WebSocket connections first
+    // Close all WebSocket connections first.
+    // Await disconnects so end-of-session summary/memory writes complete before process exit.
+    const disconnects: Array<Promise<void>> = [];
     for (const [ws, connectionId] of this.connectionMap) {
-      this.sessionBridge.disconnect(connectionId);
+      disconnects.push(this.sessionBridge.disconnect(connectionId));
       ws.close(1001, 'Server shutting down');
     }
+    await Promise.allSettled(disconnects);
     this.connectionMap.clear();
     this.connectionStateMap.clear();
 
@@ -628,7 +631,9 @@ export class GatewayServer {
     });
 
     ws.on('close', () => {
-      this.sessionBridge.disconnect(connectionId);
+      void this.sessionBridge.disconnect(connectionId).catch((error) => {
+        console.warn('Session disconnect failed:', error);
+      });
       this.connectionMap.delete(ws);
       this.connectionRateMap.delete(connectionId);
       this.connectionStateMap.delete(connectionId);