Function recv 

pub async fn recv(
    duplex: &mut Duplex,
) -> Result<Option<ReplicationEvent>, FaucetError>

Available on crate features source-postgres-cdc and source-rest only.

Receive the next meaningful replication event from the server.

Returns:

• Ok(Some(event)) — the next ReplicationEvent that the caller should handle. This includes ReplicationEvent::XLogData, ReplicationEvent::Begin, ReplicationEvent::Commit, and ReplicationEvent::Message. Callers (Task 9+) can match on the full event type to observe transaction boundaries.
• Ok(None) — stream ended cleanly (slot stopped, stop LSN reached, or Duplex was shut down).
• Err(_) — network / protocol error.

ReplicationEvent::KeepAlive events are absorbed here. We deliberately do not advance the applied-LSN to the server’s wal_end on a keepalive (the previous behaviour): that position is not yet durable downstream, and advertising it as confirmed_flush_lsn would authorise Postgres to recycle WAL for changes the consumer never persisted — a crash in that window loses data (#78/#1). The applied-LSN is advanced only from the durable bookmark, via send_status_update at the start of each run; the library keeps sending its periodic Standby Status Updates (carrying that durable position) to hold the connection open. ReplicationEvent::StoppedAt is converted to Ok(None).