98f766fcd3
Inviting a member to a group that already had members put nothing whatsoever in
the transcript. Not "put it in late" -- nothing, and nothing ever if the invite
did not complete. So the one failure the user is best placed to notice, an
invite that never reached the person it was made for, was the one the app kept
to itself.
The line existed. It was written by `MarmotOutboundDao.deliveryWelcome`, which
is the wrong place for it, and the reason is the two paths through
`inviteMember` that docs/marmot-membership.md already describes. A group that is
still only its creator has nobody to inform, so its Welcome goes out immediately
and `deliveryWelcome` runs inside the invite. A group that has members must
broadcast a commit first, and its Welcome waits for a relay to acknowledge it --
`DatabaseNostrRepository.broadcastProcessed` picks the stored `MarmotCommitResult`
back up and delivers then. Every invite after a group's first therefore wrote
its transcript line a relay round trip away from the invite, if at all.
**Four separate silences, not one.** Worth listing because only the first is
about the deferral, and fixing that alone would have left the other three:
1. The deferred path wrote nothing until the ack, and nothing ever without one.
2. The write hung off `getMarmotKeyPackageById(...)?.let { getProfileByPublicKey(...)?.let { ... } }`.
Those two lookups were there to *name* the invitee, and a miss on either cost
the whole line rather than just the name.
3. `deliveryWelcome` wraps its body in `catch (e: Throwable) { logger.e(...) }`
and returned Unit, so a Welcome that could not be built reached the log and
no further.
4. `inviteMemberToChatRoom` is `@Transaction`. An invite that threw -- no MLS
state for the room, a credential identity that does not match the peer --
rolled its line back with everything else, which is right, and left no
account of the refusal anywhere durable.
And the line it did write was `messageType = "message"`, `isUserMessage = true`,
so it rendered as a chat bubble: "Invited Bob to chat", attributed to the
inviter as something they said.
**Three membership types, and the line moves to invite time.**
`ChatMessage.MEMBERSHIP_TYPES` -- `memberInvited`, `memberInviteSent`,
`memberInviteFailed` -- rendered by the transcript as system notices through
`RitualNotice`, the way the ceremony, signing and chronicle lines already are.
`memberInvited` is written by `inviteMember` and by `addMembersToChatRoom`'s
batch path, *when the invite is made*, and deliberately **inside** the caller's
transaction. Both halves of that matter and they pull opposite ways: written any
later and an invite waiting on an ack that never comes shows nothing, which is
the bug; written outside the transaction and an invite that does not survive
`addMember` leaves the room claiming one was made.
`memberInviteSent` is written by `DatabaseNostrRepository` alone. It is not
written on the immediate path, and that is not an oversight: there the Welcome
goes out in the same breath as the invite, so one line is the whole truth. It
would also be a line the transcript could not order -- `MantraConverters` stores
`Instant` as `epochSeconds`, the room query is `ORDER BY createdAt DESC`, and two
rows written in the same second tie. Only the deferred path separates the two
events in time, so only it owes a second line.
`memberInviteFailed` carries the reason, because it is the only copy the user
gets. `deliveryWelcome` now returns `Boolean` and files this line from its own
catch before returning false -- its callers had no other way to see a failure it
had already swallowed, and on the deferred path there is no invite screen left
to fail back to. `addMembersToChatRoom` reads that answer instead of a
`runCatching` that could never catch anything.
**The refusal is written from outside the transaction that rolled it back.**
`DatabaseChatRepository.inviteMember` catches, calls `announceInviteFailed`, and
rethrows. The throw is what puts a message on the invite screen now; the line is
what is still there tomorrow. Swallowing it instead would have popped the user
back to the chat as though the invite had gone out, which is the bug the
existing `runCatching` in `AddMemberToChatRoomConfirmationViewModel` was added
to stop.
**No schema change.** `messageType` is a free-form string column with a default,
so new values need no migration -- unlike the chronicle rename, which had to
rewrite the ones already stored. Nothing reindexes these either: they carry no
`marmotGroupEventId`, so `getResolvedMarmotGroupEventIds` cannot see them and
`UNRESOLVED_MARMOT_TYPES` does not name them.
Six new tests. Four on the DAO: the immediate path leaves a line naming the
invitee where the old code left none, the deferred path leaves one *and* claims
no Welcome sent before any ack, everything an invite writes is a membership type
rather than something the transcript would render as a bubble, and a refused
invite leaves no claim that one was made. Two new ones on
`DatabaseChatRepository`, which had no test file: a refused invite is written
into the room, and the caller still gets the throw.
Still open, and now said plainly in the doc rather than implied: a Participant
row carries no state saying where its invite got to. The transcript narrates it;
the `TODO: Update status of participant Invitation.PENDING -> Invitation.SENT`
is untouched. Nor does an invitee with no published key package reach the room
at all -- that fails in the view model, before there is an invite to write a
line about.
806 tests pass -- 509 jvm, 297 android.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
183 lines
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Markdown
183 lines
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Markdown
# Adding members to a Marmot group
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How members join an MLS group in this app, why the current shape has a silent
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failure mode, and what to do about it.
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This is the part of Marmot most likely to waste a day: everything compiles, the
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invite reports success, and a member simply never appears. The reason is never in
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the invite code.
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## The two paths through `inviteMember`
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`MarmotOutboundDao.inviteMember` branches on `isOneMemberInitialGroupCreation`:
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**`true` — the group is only its creator.**
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The Welcome goes out immediately via `deliveryWelcome`, which builds it and
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inserts a `GiftWrapPayload`. No commit event is broadcast and no
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`MarmotCommitResult` is stored. Correct, because there is nobody else in the group
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who needs to learn anything.
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**`false` — the group already has members.**
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A commit event (kind 445, ephemeral signer, h-tagged with `nostrGroupId`) is
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broadcast so existing members advance their epoch. The Welcome is *not* sent.
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Instead `commitResult.welcomeBytes` is stored on a `MarmotCommitResult`, and
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`DatabaseNostrRepository` picks it back up when the relay acknowledges the commit
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and only then calls `deliveryWelcome`.
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The deferral is deliberate: the invitee must not join an epoch the existing
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members have not reached yet.
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## Which branch is taken, and why nobody chooses it
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`inviteMember` derives it:
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```kotlin
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val isOneMemberInitialGroupCreation = mlsGroup.members().size == 1
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```
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Read before `addMember` advances the tree, and `members()` skips empty leaves so it
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stays right for a group that has had members removed.
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No caller passes it, deliberately. None of them is in a better position to know,
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and both that tried got it wrong: `inviteMemberToChatRoom` hardcoded `false`, so
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**every group's first invite took the deferred path** even though the group was
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still just its creator. That was wrong twice over — the commit had no audience,
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and the Welcome was then gated on a relay acknowledging it. With
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`Relays.DefaultDMRelayList` down to a single relay, that meant the first invitee
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of every group depended on one ack for an event nobody needed.
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## Why this fails silently
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`MarmotInboundManager` refuses anything from a future epoch outright, on both
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wire formats:
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```
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PrivateMessage epoch N is ahead of local epoch M; ignoring
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Commit epoch N is ahead of local epoch M; ignoring
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```
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There is no queue and no replay for either. A commit that arrives before its
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recipient's Welcome is **dropped, not deferred**, and that member never advances.
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`EPOCH_RETENTION_WINDOW` (5) retains *past* epochs so late messages can still be
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decrypted; it does nothing for messages from ahead.
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Under the old hardcoded `false`, inviting two admins back to back went:
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1. invite admin 1 → commit 1 broadcast immediately, Welcome 1 waits for ack 1
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2. invite admin 2 → commit 2 broadcast immediately, Welcome 2 waits for ack 2
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Both commits were on the wire before either Welcome. If commit 2 reached admin 1
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before Welcome 1 did — different transports, no ordering guarantee, one a gift
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wrap and the other a kind:445 — admin 1 dropped it and was stuck an epoch behind,
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while the coordinator saw two successful invites.
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Deriving the flag narrowed this, but did not close it: for n ≥ 3 the window
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between Welcome 1 and commit 2 remained.
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**Batching closes it.** When the membership is known up front, every member goes
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into one commit, so no member ever has to process a commit for an epoch they were
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not yet in — the race has nothing left to lose. See below.
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## The condition holds at any group size
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"The group has nobody to inform" is true exactly once, on the first invite, whether
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the group ends up with 2 members or 30:
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| invite | `members().size` | branch | correct because |
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|---------|------------------|------------------------------|---------------------------|
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| admin 1 | 1 | immediate Welcome, no commit | nobody to inform |
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| admin 2 | 2 | commit + deferred Welcome | admin 1 must advance |
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| admin 3 | 3 | commit + deferred Welcome | admins 1–2 must advance |
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Commit 2 is encrypted with `commitResult.preCommitExporterSecret` — the epoch-1
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secret, which admin 1 received in their Welcome — so they can decrypt it and
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advance.
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## Batching every add into one commit
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`MarmotOutboundDao.addMembersToChatRoom` stages every member with `proposeAdd` and
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issues a single `commit()`. `MlsGroup.addMember` is just those two in one call, and
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`pendingProposals` is a list, so nothing in MLS objected.
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One commit produces **one** Welcome: `buildWelcome` emits an `EncryptedGroupSecrets`
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per added member, and each joiner finds its own entry by key package reference. The
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blob is shared; delivery is still per peer, because each Welcome event is tagged
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with that peer's key package.
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Both callers that know their membership up front now use it —
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`SelectChatRoomTypeViewModel.inviteMembers` at room creation, and
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`DkgRitualViewModel.inviteAdmins` for the `#admins` room.
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### Why this needed no schema change
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Batching at creation time means the single commit happens while the group is still
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only its creator. That takes the immediate-Welcome branch: no commit is broadcast,
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and `MarmotCommitResult` is never written. The bookkeeping that assumes one peer per
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commit is simply not on the path.
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So `addMembersToChatRoom` batches **only** when `members().size == 1`, and falls
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back to inviting sequentially otherwise. Batching into a group that already has
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members would take the deferred branch, where `MarmotCommitResult.peerKeyPackageEventId`
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is singular and `DatabaseNostrRepository`'s ack-triggered delivery expects one
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Welcome. Making that work means holding a list of peers there and fanning out on
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acknowledgement — still outstanding, and only needed for adding several members to
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an established group, which nothing currently does.
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### Ordering within the batch
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The group state is persisted after `commit()` and before any Welcome is delivered,
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so a crash between the two leaves the group at the epoch the Welcomes describe
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rather than one behind it.
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## What the room is told
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An invite writes three kinds of line into the room's transcript, none of which
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travels — see `ChatMessage.MEMBERSHIP_TYPES`. They exist because the deferral
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above is invisible from anywhere else: the screen that asks for an invite closes
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the moment the commit is made, and everything that can still go wrong goes wrong
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after that.
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| line | written by | says |
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|-----------------------------|-----------------------------------------|---------------------------------------|
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| `TYPE_MEMBER_INVITED` | `inviteMember`, `addMembersToChatRoom` | the membership change was made |
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| `TYPE_MEMBER_INVITE_SENT` | `DatabaseNostrRepository` | the deferred Welcome went on the wire |
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| `TYPE_MEMBER_INVITE_FAILED` | `deliveryWelcome`, `DatabaseChatRepository` | it did not, and why |
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The invite line is written **when the invite is made**, inside the caller's
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transaction. Both halves of that matter: written any later and an invite waiting
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on an ack that never comes leaves the room showing nothing, which is what this
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looked like before; written outside the transaction and an invite that does not
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survive `addMember` leaves the room claiming one was made.
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Only the immediate branch's Welcome goes out in the same breath as the invite, so
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only the deferred branch owes a second line. Where the two are one event, one line
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is the whole truth — and `createdAt` is stored to the second, so a second line
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would be one the transcript could not reliably order after the first anyway.
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A refusal is the awkward case, because rolling the transaction back is right and
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takes the account of it with it. `DatabaseChatRepository.inviteMember` catches,
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writes the failed line from outside the transaction, and rethrows — the throw is
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what puts a message on the invite screen now, the line is what is still there
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tomorrow.
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## Other things that bite
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**Sequential invites each advance the epoch.** Where they still happen — the
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fallback in `addMembersToChatRoom` for a group that already has members, and any
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direct `inviteMember` call — the room must be re-read from the database between
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them. A snapshot taken before the previous invite builds its commit on state the
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group has already left, and the symptom is a conflicting commit rather than an
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error.
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**A member with no published key package cannot be added.** A Marmot invite needs
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the invitee's `MarmotKeyPackage`. Both call sites look it up with a timeout and
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collect the ones that failed. That is still only a log and a returned list —
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nothing puts it in the room, because it happens before there is an invite to write
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a line about. The `TODO: Update status of participant Invitation.PENDING ->
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Invitation.SENT` at the Welcome delivery site is the same gap seen from the other
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end: the transcript lines above say what happened, but a Participant row still
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carries no state saying where its invite got to.
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**`deliveryWelcome` uses `Relays.DefaultDMRelayList`, not the room's relays.**
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There is a `TODO: Get localChatRoom relays...` on the ack-triggered call site.
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