The previous handler (commit ce33ccf + its 403 extension) wiped hmac_secret
and reset peer status to 'pending' on any 401/403 from an active peer. This
collapsed three distinct failure modes — transient clock skew, legitimate
split-brain, active MITM attempt — into "silently establish new trust
immediately." The remote's /peer/accept idempotent-200-no-update safeguard
then prevented the re-handshake from actually working, producing a 1-req/sec
loop observed during backlog #16 verification.
New behavior: increment consecutive_auth_failures, apply backoff to outbox
entries. At AUTH_FAILURE_THRESHOLD (5) transition to needs_attention,
preserve hmac_secret, surface delivery-impossible to affected users,
notify admins. Secret is NEVER wiped in response to a network-observed
401/403.
Part of backlog #19.
Jannis Braun
e5afd376d2