The activity write took a Go-side timestamp, which is exactly what
MarkPeerConnectedIfNewerSession documents as the cause of previous ordering
bugs: a value read before the write can land after a connect that stamped
CURRENT_TIMESTAMP, dragging LastSeen backwards.
The write now uses the database clock like the other status writers, so the
column only ever moves forward. The throttle is unaffected; it reads the
peer already in hand and never needed the write's timestamp.