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Closes the privilege escalation: any BAN holder could ban the authorities above
them — including the owner — because the Banlist gate checked only the BAN bit.
Once banned, a member loses all authority (`hasPermission` is `!isBanned && ..`)
and honest clients drop their events, so a single edition from the most junior
moderator permanently silenced every admin above them.
CORD-04 §3 requires the rank half: "One hard rule binds every action: the actor
must hold the required bit and strictly outrank its target — equal cannot act on
equal (an admin cannot ban a peer admin)", restated as §5 step 3. Only §4, which
defines the Banlist, states the bit half alone — which is why both this client
and Armada shipped the same rank-blind gate.
§3 is stated per TARGET while the Banlist is one whole-list document, so it is
enforced as a DELTA rule: an edition may only add or remove npubs its signer
strictly outranks, judged against the roster settled behind it; the owner is
never a valid target (position 0 is "supreme and unremovable"); and entries the
signer may not act on are IGNORED rather than rejecting the edition, so one bad
entry cannot discard the bulk-ban §4 recommends as the collision remedy, and a
rogue cannot grief the list by forcing rejections.
ConcordModeration.currentBanned now reads the honored banlist through the
resolver instead of decoding the raw head. Besides picking up the fork healing
it was missing, this closes a laundering path: our own next ban/unban would
otherwise re-publish an entry our fold refuses, under our signature.
BREAKING (consensus): Armada has not shipped this rule, so banlists can differ
between clients until it does — we now ignore a ban Armada honors whenever the
signer did not outrank the target. Shipping the spec-conformant behaviour was
judged better than continuing to honor an escalation. Write-up to send upstream
is docs/concord-banlist-rank-conformance.md.
The three tests added in 0ae6bc6698 as @Ignore-d documentation now pass and are
un-ignored; two companions (a moderator still bans a plain member, the owner
still bans anyone) passed throughout and pin what the fix had to preserve.
Full :quartz:jvmTest and :commons:jvmTest suites green.
Still open and documented, not addressed here: a banned BAN holder can lift
their own ban (a fixpoint-ordering question that needs a spec ruling), and a
forked ban survives an unban that does not chain onto it.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>