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A member added after the work was done sees none of it, and nothing in the app will ever show it to them. Two independent reasons, and the second is the one that surprises people. MLS gives no history: a Welcome carries the ratchet tree at the current epoch, not the transcript, and `MarmotInboundManager` drops anything from an epoch it holds no keys for. That is forward secrecy working rather than a gap to close. But group-signed events never travel at all. `FrostSigningManager.complete` says so in as many words -- a signed event authored by the threshold key cannot go out as an inner event, because the outbound pipeline would re-author it as its sender and strip the group's signature off -- so every device *derives* the finished event from its own `FrostSigningItem` rows. A member who was not in the session has no items, and no later message carries the event. So the second problem does not follow from the first and is not fixed by fixing it: even a member who could decrypt the whole back-transcript would still hold nothing an artifact, chapter or chunk could be built from. Which makes an archive not a convenience but the only path, and fixes the line the design has to hold: **it carries what the group signed, never the chat.** Restoring the chat would undo forward secrecy on purpose, and a signed event is the only thing a new member can check for themselves. **The property the whole plan rests on is already true.** A room's id *is* the group's threshold key derived at the room's path -- `GroupKeyState.verifies` and `FrostSigningManager.signingPath` hold that invariant from their own ends -- so `isSignedByGroup`'s three checks collapse to `event.pubKey == chatRoomId`, an id check and a signature verify. No key state row, no threshold key, no path, no lookup. A member who can name the room can verify its signatures, which is exactly the position a new member is in, and it means the sender of an archive does not have to be trusted at all. **Two guards the plan makes non-negotiable.** Nothing on the inbound nip30303 path verifies a signature today, and that is currently correct: rumors carry an empty sig and are authenticated by the MLS frame, so nothing on the wire has ever claimed group authorship. An archive is the first thing that does, so the verify is the feature's entire security rather than hardening on top of it. And verification turns "group-signed" into an admission ticket for the apply path, which is a wider door than it looks: a `GroupKeyStateEvent` is group-signed and would pass perfectly, so an archive could replay a genuine old one and re-point what the room signs with. The archive therefore carries an allowlist of document kinds, checked outbound and independently inbound -- the same shape, and the same reasoning, as the cap on `k` in frost-batch-signing.md. **Push and pull, in that order of appearance and the reverse order of importance.** Pushing an archive after the Welcome is what the question asked for, and on its own it fails the way marmot-membership.md describes: it is an application message in the epoch the add created, so one that beats the Welcome there is dropped rather than deferred, silently, while the inviter sees a success. So the joiner asks instead -- a request is proof it has processed its Welcome, and it covers the reinstall and the second device, which no invite-time push can. The push stays as a latency optimisation, deliberately phased after the thing that makes it safe. Nine phases: the verifier, the events, assembling an archive, applying one and the sweep that lets pages arrive out of order, the request, the push, UI, the cross-device tests, and rollout. The sweep needs no new table -- the inbound path already stores every inner event it decrypts, so it is the shape `FrostSigningManager.replayStoredMessages` already has. Also written down, because it is the first thing this will be reported as a bug for: an archive lets a new member *read* everything and does not let them sign anything. `proposeSigningBatch` wants a secret share and a place in the ceremony, and a group that re-runs its ceremony derives a different room rather than re-keying this one. Closing that needs share resharing, which is a great deal more work than this and is the thing to build after it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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2.9 KiB
mantra docs
Notes on the parts of this app whose behaviour is not recoverable by reading the code alone — where the reasoning lives in a protocol, a failure mode that is silent, or a decision that looked arbitrary and was not.
| document | covers |
|---|---|
| shared-key-ceremony.md | ChillDKG over NIP-17: the rounds, the approval gates, the chat transcript, participant ordering |
| shared-key-derivation.md | deriving further keys from the group's threshold key with FROST tweaks — why not BIP32, why no chain code, and the one rule that must not be broken |
| frost-batch-signing.md | signing several events in one ceremony — why one nonce can never cover two messages, and the phased schema, wire and UI work that follows from it |
| marmot-membership.md | how members join an MLS group, and the epoch race that makes a missing member look like a successful invite |
| member-archive.md | handing a member added after the work was done the group's signed record — why the events are not on the wire at all, and why the room's id is enough to verify them |
| marmot-direct-messages.md | a one-to-one message inside a group as a stock NIP-59 gift wrap — what its MIP-03 carve-out costs, why the sender cannot read their own, and the one query that would broadcast it |
| mls-skipped-keys.md | why a group event that arrives a moment late is dropped for good, which flows trigger it, the quartz fix, and the partial mitigation in this app |
| long-running-sync.md | the chat subscriptions that stay open instead of pulling once per screen — why the request queue could not simply hold one, and how the group filter follows the room list |
| dead-code.md | code in the sync and relay stack that nothing calls, why each piece is still there, and which of it is a bug rather than a leftover |
| jvm-target.md | what desktop support cost, phased — why the native chain was already done, why an empty source set in our phoenix fork was the real blocker, and why DAO tests need none of it |
Start with the ceremony if you are new to this area; the Marmot notes all assume it. Read the skipped-keys note before debugging any "the other device never got it" report — it is silent, and it looks like every other kind of delivery failure. The sync note stands alone, and the dead-code inventory reads as a follow-up to it. The batch-signing note is a phased plan that has been built: read it after the derivation note, whose one rule is the same one it is built around. The member archive note is a phased plan that has not been built, and reads as the membership note's unanswered half: what a member who joins late can be given, and the one thing they cannot. The jvm-target note is unrelated to all of them: it is a build and packaging story.