The consumers applications (which interface with Tank brokers via a Tank client library) are responsible for maintaining the sequence number they are consuming from.

Suppose one such application is consuming every new event that's publishing ("tailing the log"). As soon as another application successfully publishes 1 or more new messages, the consumer will get them immediately. If the application that attempted to publish failed to do so, or didn't get an ACK for success, then you are guaranteed that no new message(s) were published(i.e no partial message content).

I am not sure if that answers your question, if not, can you please elaborate?