A frame at or before the seeded watermark is a duplicate of an earlier generation and is acknowledged, never delivered again (serial compare within the receive window). A Connect that precedes the current generation's within the window is a stale copy of an earlier attempt: it is answered like a repeat (Accept owed or Ack), changes no state and does not refresh liveness. A Connect unanswered for 3 s is replaced by a fresh Connect with a newly drawn sequence and the same payload. In server mode a Connect from another endpoint is always a new generation. The initial sequence is unset by default and each session draws its own; the public random helper is removed.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>