Harden the insecure-link outbox bound; document the second-replay presence gap and the courier metadata tradeoff

Review follow-ups on the canDeliverSecurely gate:

- flushOutbox no longer counts connected-but-insecure flushes toward the
  maxSendAttempts drop: the message was actually transmitted over a live
  link, so a peer whose Noise handshake stalls across reconnect flapping
  must not burn through the cap and lose the store-and-forward copy the
  gate exists to preserve. Retention stays bounded by the 24h outbox TTL
  and the per-peer FIFO cap; acks still clear it. Attempt-counting stays
  for reachable-only (heuristic) sends. Regression test: >8 connected-
  insecure flushes keep the retained copy, drop callback never fires.

- Document the known second-replay presence gap: linkBoundToOtherPeer
  reads the binding before rebindLinkAfterVerifiedDirectAnnounce steals
  the link, so once a first replay has rebound a link to an absent
  victim's ID, a second replay marks the victim connected. Presence
  display only — DMs stay on the retain+courier path via the router
  gate. Not closed at the announce layer because the post-rebind state
  is indistinguishable from a legitimate rotation/reconnect heal (a
  supported, field-verified flow). Covered by a two-announce test.

- Note the accepted courier-spray metadata tradeoff at the connected-
  insecure send: nearby verified peers receive a sealed copy (they learn
  a DM exists, never its content), cleared on ack.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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jack 2026-07-09 15:19:38 +02:00
commit 5017c232f4
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