AppSync subscriptions: waiting for start_ack can still result in missing events

It seems like that when AppSync returns a start_ack message in response to a subscription start it won't necessarily mean that all future events will be delivered. Subscriptions are the mechanism to deliver real-time events from AppSync. It is based on WebSockets and its protocol is documented here . In the protocol, a client needs to send a start message with the GraphQL query to start receiving…