Unauthenticated /peer/accept must not overwrite hmac_secret for peers in needs_attention, same as active. needs_attention means 'auth trust broke and we don't know why' — letting an unauthenticated request flip it back would reintroduce a path for silent HMAC rotation via the outbox-401 loop the rest of #19 closes. Legitimate recovery is the admin 'Reset peering' action (next task).