ReconnectSupervisor swallowed a transport failure reported while Replaying,
so a restarted event stream refused/ended a round trip after the replay
began still let the replay go Healthy over a dead stream (and the next
advise's re-report restarted at attempt 1 with no backoff). A failure
reported during Replaying is now remembered and turns that attempt's
success into a retry with backoff. ReplayAsync's synchronous dead-pump
throw yields to a teardown's cancellation.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
Joseph Doherty
d80bdf6369