add nip29 document

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# Using the groups backend
`crates/nip29` is the backend for [NIP-29](https://github.com/nostr-protocol/nips/blob/master/29.md)
relay-based groups. It is a GPUI crate: it owns one registry entity and one entity
per group, subscribes to the relays, caches everything locally and hands the UI
`chat::Message`s. It owns no strings a user reads — the UI layer decides every
rendering. This document is the map from a UI action to the calls it makes.
A group is a `(relay, id)` pair. The relay enforces membership and signs the
group's state; there is no cross-relay identity, no encryption, and no portable
"create". The same `id` on two relays is two groups (a fork), which the backend
models as two entities.
## Modules
| File | Owns |
| --- | --- |
| `src/protocol.rs` | Pure NIP-29 value types and their `impl` blocks: `GroupId`, `GroupKey`, `GroupReference`, `GroupMetadata`, `GroupAdmins`/`GroupMembers`/`GroupRoles`/`GroupParticipants`, `Pin`/`GroupPins`, `LivekitSession`, `GroupList`/`GroupListEntry`, `Membership`, `TimelineWindow`, plus the filter and event builders on `GroupId`. No I/O. |
| `src/group.rs` | The `Group` entity: one group's state, timeline, membership, writes, the envelope cache helpers and the two LiveKit calls. `GroupEvent`. |
| `src/lib.rs` | The `GroupsRegistry` global, `init`, the notification pump, the account's `10009` list, the fork watch and relay browsing. `GroupsEvent`. |
`protocol` is re-exported at the crate root (`pub use protocol::*`), so callers
write `nip29::GroupKey`, `nip29::GroupMetadata`. `group` is re-exported the same
way (`Group`, `GroupEvent`).
The crate's constants are the protocol's: `RENDER_KINDS` (`1`, `9`, `11`, `1111`,
`7`), `STATE_KINDS` (`39000`–`39004` and `39005`), `MEMBERSHIP_KINDS` (`9000`,
`9001`), `PIN_LIST` (`39005`), `UPDATE_PIN_LIST` (`9010`), `TIMELINE_WINDOW`
(50) and the `previous`-tag shape (3 refs, 8 hex chars).
## Turning it on
One line, after the other registries and gated on nothing — the registry does its
own sign-in check:
```rust
nip29::init(cx);
```
It builds the global entity, subscribes to `NostrRegistry`, and on the first
sign-in (or a signer change) resets its state, restarts the pump and loads the
account's `10009`. No groups exist before a sign-in, and everything is torn down
when the signer changes, so the crate never leaks one account's groups into
another.
`nip29::init(cx)` is already called in `desktop/src/main.rs` and `web/src/lib.rs`.
```rust
use nip29::GroupsRegistry;
let groups = GroupsRegistry::global(cx); // Entity<GroupsRegistry>
groups.read(cx).groups(); // &[Entity<Group>]
groups.read(cx).group(&key, cx); // Option<Entity<Group>>
```
`GroupsEvent` is emitted on the registry; read it back on the event. The sidebar
subscribes to `GroupsEvent` and renders `groups()` — pending and refused groups
are in that list alongside members, and their `Group::membership()` says which.
```rust
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum GroupsEvent {
Updated,
Error(String),
}
```
`Updated` fires on any change to `groups()` or to a browse result; `Error` is only
emitted when publishing a `9007` (create) is refused, and carries the relay's
message.
## Value types
```rust
use nip29::{GroupId, GroupKey, GroupReference, GroupMetadata};
let id = GroupId::new("pizza-lovers")?; // trimmed, non-empty
let key = GroupKey::new(relay_url.clone(), id); // the (relay, id) pair
```
A `GroupKey` is the identity of a group *as this backend sees it*: everything
that addresses a group — `group`, `join_key`, `create`, `load_more`, `leave`,
`browse` results — takes one. `Group::key()` returns the one an entity was built
with, and `GroupReference::key()` returns the one a link resolves to.
A reference is a link, and only a link:
```rust
let reference = GroupReference::parse("naddr1…?invite=CODE")?; // or .parse::<GroupReference>()
```
`GroupReference::parse` (and `FromStr`) accepts only a kind-`39000` `naddr` with a
relay hint. The `?invite=` suffix the NIP defines is split off before bech32
decoding and lives on `reference.invite()`; a missing relay hint is an error,
because there is nowhere to send the join request. `id@relay` is deliberately not
accepted.
`GroupMetadata` is both the read model and the `9002`/`9007` payload, and it is
`Default`:
```rust
let metadata = GroupMetadata {
name: Some("Pizza Lovers".into()),
private: true,
..Default::default()
};
```
`parse(event)` fills it from a relay-signed `39000` (and keeps the event's id and
author privately, which is what `naddr` is built from). `name()`, `supports(kind)`
and the public flag fields (`private`, `restricted`, `hidden`, `closed`,
`livekit`, `parent`, `children`, `supported_kinds`) are what a group header reads.
`supports` distinguishes "tag absent" (all kinds) from "tag present with no
values" (no kinds) — that is the difference between a normal group and an AV-only
one.
## The account's group list
`10009` ("simple groups") is the member's own list of memberships, synced across
devices. The registry keeps it in `list: GroupList` and owns its whole lifecycle:
it is loaded at sign-in, `upsert`ed on join/create, `remove`d on leave, and
re-published to `to_nip65()` after every change. A caller never touches it.
```rust
// `10009` tag shape: ["group", id, relay, name?] plus ["r", relay]
```
Loading is a subscription plus a database read, the same read model as everything
else: subscribe to our own `10009` under `nip29-list`, then read the newest from
`client.database()` and merge it. A newer list arriving from another device is
merged union-only — the backend never diffs, so a removal another client made is
not detected, and the local state is never walked backwards. `GroupList::parse`
requires `["group", id, relay]` and takes the third value as the display name.
## Joining
```rust
GroupsRegistry::global(cx).update(cx, |registry, cx| {
registry.join(reference, cx); // or join_key(key, invite, cx)
});
```
`join` is `join_key(reference.key(), reference.invite().to_owned())`, and
`join_key` is what every other path calls too, because a browse result has a key
and no `naddr`. The sequence is:
1. `ensure` the group: create the entity, register it in `groups()`, subscribe to
its relay (the standing `grp-<hash>` REQ, below) and reload it from the local
cache.
2. Add the entry to `10009` optimistically and publish the list, so the group is
listed the moment the user asks for it.
3. Publish `key.id().join_request(invite, "")` — the `h` tag plus, when the link
had one, a `code` tag. `Group::mark_pending(now)` runs immediately, so
`Group::membership()` is `Pending { since }` while the relay decides.
The relay either emits `9000` (the standing subscription folds it into
`Membership::Member`), or answers the `9021` with `OK false` — the registry
catches that and sets `Membership::Refused { reason }` from the relay's message.
The NIP promises that message explains whether the rejection is final, pending
review or payment-required, so show it verbatim and offer a retry. A join to a
`closed` group is refused the same way, unless the invite code is honoured.
Join needs no `39000` first: nothing is fetched, the `9021` is the whole request.
A hidden group needs no special handling either — the state simply never arrives.
## Reading a group
`Group` is an entity with no protocol state in the view. A panel reads it and
subscribes to `GroupEvent`:
```rust
use nip29::{Group, GroupEvent};
let Some(group) = registry.read(cx).group(&key, cx) else {
return;
};
let messages = group.read(cx).messages(); // &[chat::Message]
```
```rust
cx.subscribe(&group, |this, group, event, cx| match event {
GroupEvent::Incoming(..) | GroupEvent::Updated => cx.notify(),
GroupEvent::Refused(reason) => this.show_error(reason, cx),
GroupEvent::Eose => this.stop_spinner(cx),
GroupEvent::Sent(_) => {}
})
```
`GroupEvent` is the full surface:
| Variant | Means |
| --- | --- |
| `Incoming(Event)` | a fresh renderable message was folded in (use it for system notifications when the window is inactive) |
| `Sent(Event)` | our own event was accepted by the relay; the registry re-reads the group, the panel normally ignores it |
| `Updated` | metadata, state, membership, pins or a finished page changed |
| `Eose` | the standing subscription settled |
| `Refused(String)` | the relay `CLOSED` the standing subscription, with its message |
The reads are all accessors: `key`, `metadata`, `members`, `admins`, `roles`,
`participants`, `pins`, `membership`, `elsewhere`, `messages`, `loading`,
`loading_more`, `oldest`, `refused`.
### The read model
There is **no `fetch_events` anywhere** in the crate. A group is read by
subscribing, then querying the local database — the same model as `crates/chat`
and `crates/community`:
```
subscribe grp-<hash> the global pump observes every REQ on the client
│ (timeline + state + membership filters, one relay)
▼
save_envelope 30078, d = event id, r = "<relay>|<id>", k = kind
│ content = the raw event JSON, signed by crate-local keys
▼
load_envelopes query by the r tag, parse, sort by created_at
│
▼
Group::hydrate the only place entity state changes
```
The standing REQ carries three filters under one id: the timeline
(`GroupId::timeline_filter(100)`), the relay state (`state_filter`) and our own
membership (`membership_filter(me)`). Its id is `grp-` plus 8 hex of a hash of the
key — NIP-01 caps ids at 64 characters, and the pump needs a prefix to recognise
its own subscriptions, so the real key is held in the registry's `routes`, not
encoded in the id.
The envelope cache is what makes the timeline fork-safe and restart-safe without
teaching the nostr database about relays (a stored event carries no origin): the
`r` tag *is* the relay scoping. It is also why every event is re-read instead of
consumed off the wire — the pipeline dedups, sorts and survives a restart, and a
page, a live tail and a local send all take the same path.
`hydrate` partitions an envelope run:
- `STATE_KINDS` → `metadata`, `admins`, `members`, `roles`, `participants`,
`pins` (relay-signed, read-only, addressable by `d`).
- `MEMBERSHIP_KINDS` → our membership only (see below).
- `RENDER_KINDS` → a `chat::Message`, inserted in `created_at` order.
- everything else is kept only for the `previous` window.
Every `h`-tagged event feeds the window regardless of kind. The window is the
NIP's timeline reference: the last 50 events seen on that relay, excluding our
own, first 8 hex characters of their ids, up to 3 per send. The write path
attaches it automatically via `Group::previous_tag(me)`, so callers never build
`previous` themselves.
`Group::loading()` is true until EOSE; `Group::refused()` carries the relay's
`CLOSED` message when it never settles. A relay may answer a restricted or
private group with `restricted:` / `auth-required:` — the state stays, the group
just reads empty, and that is not an error toast.
### Older messages
```rust
GroupsRegistry::global(cx).update(cx, |registry, cx| {
registry.load_more(&key, cx);
});
```
It is a no-op while a page is in flight (`Group::loading_more()`) or before
anything is cached. Otherwise it sends a `pg-<hash>` REQ (`timeline_page(50,
until)`) alongside the standing one — paging must not replace the live tail — and
the pump caches each page event and reloads the group exactly like a live event.
The cursor is `Group::oldest()`, the oldest `h`-tagged event ever hydrated; `until`
is inclusive, so a page repeats its first event, which the dedup absorbs for free.
EOSE, a page `CLOSED` or the 10s auto-close all clear the spinner.
One relay behaviour is worth a spinner that can be cancelled: a relay that accepts
the REQ but never EOSEs leaves `loading_more` true, because the auto-close closes
the subscription locally with no notification at all.
## Sending
Every write goes through one path — `Group::dispatch` builds the event with
`key.id()` and the current `previous` tag, `Group::publish` adds and connects the
relay, signs with the app signer and sends to that one relay:
```rust
let sent = group.update(cx, |group, cx| group.send_message(&text, replies, cx));
cx.spawn(async move |_, _| {
if let Err(error) = sent.await {
// the relay's OK-false message, verbatim: "invalid: ...", "restricted: ...", "duplicate: ..."
}
});
```
| Call | Wire |
| --- | --- |
| `send_message(content, replies: Vec<EventId>, cx)` | kind `9` + `h` + `e` per reply |
| `send_reaction(target: EventId, emoji: String, cx)` | kind `7` + `h` + `e` |
| `put_user(public_key, roles, cx)` | `9000` |
| `remove_user(public_key, cx)` | `9001` |
| `edit_metadata(&GroupMetadata, cx)` | `9002` |
| `delete_event(EventId, cx)` | `9005` |
| `create_invite(code, cx)` | `9009` |
| `update_pins(Vec<Pin>, cx)` | `9010` |
Each returns `Task<Result<()>>` and each resolves only once the relay has
answered: `OK true` emits `GroupEvent::Sent` and the registry reloads the event
through the normal cache path, so the timeline shows a send without waiting for
the live tail; `OK false` is an `Err` carrying the relay's message. There is no
offline queue — NIP-29 relays reject late publication, so a send either goes now
or fails visibly.
Kind 9 is the default message kind. When `metadata().supports(Kind::ChatMessage)`
is false — an AV-only group, or one whose `supported_kinds` omits it — disable the
composer instead of sending a kind the relay does not take.
`replies` are plain `EventId`s; they become `e` tags. There is no thread model in
the backend beyond that: `chat::Message::replies_to` already reads them back.
## Membership
Membership is derived from the relay's own events, never guessed:
```rust
pub enum Membership {
Unknown,
Pending { since: Timestamp },
Member,
Refused { reason: Option<String> },
Removed,
}
```
`Membership::from_events(&[...], me)` takes the newest `9000`/`9001` whose `p`
tags name us — on an exact timestamp tie it prefers `9001` — and `Unknown` when
there is none, which the NIP says means "not a member". The `Group` keeps only
the membership events that mention us, so `refresh_membership` costs nothing.
`Pending` and `Refused` are the two local states, because the relay does not fold
them into an event: the join path sets them from the `9021` send result. A
`Member` is never overwritten by `mark_pending` or `mark_refused`, so a stale
refusal cannot demote a member.
Count a member who is `Unknown`, `Pending` or `Refused` as "not in the room" for
writes, but keep the row visible: pending and refused groups stay in `groups()`
with their state on the row.
## Moderation
The `9000`–`9010` writes are on `Group` and share `dispatch`, so they are the
same shape as sending a message. The backend does not enforce authority — the
relay owns roles and its own policy — it only surfaces the refusal. Gate the UI
on the caller appearing in `Group::admins()` (each entry is a pubkey plus its role
labels), read the relay's supported roles from `Group::roles()`, and let the relay
reject anything it does not want.
`edit_metadata` takes a `GroupMetadata`, so a form can start from
`Group::metadata().cloned().unwrap_or_default()`, mutate, and send. `children`
must carry every child tag, because a `9002` that drops one is rejected by the
relay; the builder re-emits them from the struct.
`delete_event` is a **relay** instruction only. The relay stops serving the event,
but the local timeline keeps it: the backend does not evict the envelope or the
message, so a deletion the relay accepted is still visible locally until the UI
phase drops it. That is the one moderation write left incomplete (see below).
## Pins
```rust
use nip29::Pin;
let pins: Vec<Pin> = vec![Pin::Event(event_id), Pin::Address(coordinate)];
group.update(cx, |group, cx| group.update_pins(pins, cx));
```
`9010` carries the whole list, so pinning, unpinning, reordering and clearing are
all one call. The relay mirrors it into `39005`, which is in `STATE_KINDS` — so
`Group::pins()` reflects the accepted list on the next reload.
## Subgroups
`GroupMetadata` carries `parent: Option<GroupId>` and `children: Vec<GroupId>`,
and the metadata builder re-emits both, so a create or edit can declare the link.
There is no tree helper: the tree is scoped to one relay, so assemble it from
`Group::metadata()` across `groups()` where all the children have the same relay.
Membership and admin roles do **not** cascade across the link — each group's
`9000`/`9001` and `39001` are authoritative for its own scope — so never infer
access from a parent.
## LiveKit
Two calls, both off the foreground thread and both `&App`:
```rust
if group.read(cx).metadata().is_some_and(|m| m.livekit) {
let available = group.read(cx).livekit_supported(cx).await?; // GET /.well-known/nip29/livekit
let session = group.read(cx).livekit_session(cx).await?; // LivekitSession { token, server_url }
}
```
`livekit_supported` is an unauthenticated GET that answers `true` only for `204`.
`livekit_session` signs a NIP-98 `Authorization` header (`27235`, with the `u` and
`method` tags the SDK's verifier demands) and returns the JWT and server URL; the
token is a per-join artifact, returned not stored. Both requests carry an explicit
`RedirectPolicy::NoFollow` and a 10s timeout, because the header is signed for
exactly one URL and GPUI applies no timeout unless asked. The backend stops at the
JWT — no LiveKit client library is involved — so the AV room itself is UI work.
Check `metadata().livekit` before offering the button, and read
`Group::participants()` (kind `39004`, `participant` tags, relay-published) for
who is live. Absent and empty are the same value there: nobody is in the room.
## Forks and migration
A `10009` on the *admins'* relays says where each of them thinks the group is. The
registry keeps one standing `nip29-forks` subscription over
`{authors: every admin of every group, kinds: [10009]}` on `ReqTarget::auto` —
which is why it still works when the group's own relay is down — folds each event
into a per-author list, and recomputes every group's `elsewhere`.
```rust
if let Some(moved) = group.read(cx).elsewhere() {
// the group may have moved or been forked; offer:
registry.update(cx, |registry, cx| registry.join_key(moved.clone(), None, cx));
}
```
`elsewhere()` is `Some(key)` when an admin of the group lists the same group id at
a different relay. The data cannot distinguish a move from a fork, hence the
neutral name; nothing is auto-joined, because the NIP asks the client to *offer*.
Evaluation is incremental on each event rather than batched on EOSE, since
`ReqTarget::auto` fans out and an early EOSE would evaluate against one relay's
partial view. A 15-minute background tick re-subscribes regardless, which is the
recovery path for a subscription that died or a client that was offline.
`Monitor` is not adopted: it is only reachable through `ClientBuilder::monitor`,
so nothing can read per-relay status without changing `crates/state`. The fork
check does not need it — the admin pubkeys come from the cached `39001`, so the
check runs with the relay gone, just at the next tick.
## Browsing a relay
```rust
use nip29::Browse;
registry.update(cx, |registry, cx| registry.browse(relay_url.clone(), cx));
let browse: Option<&Browse> = registry.read(cx).browsed(&relay_url);
```
`Browse` is `{ relay, loading, groups: Vec<GroupCandidate> }`, where a candidate
is a `GroupKey` plus its parsed `GroupMetadata`. `browse` connects the relay,
sends one auto-closing `39000` REQ (limit 500, EOSE or 10s) and returns
immediately; the pump folds each relay-signed metadata event into the result. Read
it back in a `GroupsEvent::Updated` handler, which also fires when the browse
settles (`loading` flips false on EOSE or a refusal). Join a result with
`join_key(candidate.key, None, cx)`.
One caveat: `Browse::loading` can stick if the relay accepts the REQ and never
EOSEs, because the auto-close timeout closes the subscription locally with no
notification. Treat it as "still trying", not as an error.
## Creating a group
```rust
let metadata = GroupMetadata { name: Some(name), ..Default::default() };
registry.update(cx, |registry, cx| registry.create(key, metadata, cx));
```
Creation mirrors join: `ensure` the entity, add it to `10009` and publish optimistically,
then send the `9007`. There is no NIP-11 check to lean on, so "where the relay
supports it" is enforced by the relay refusing the event — on refusal the registry
forgets the group and emits `GroupsEvent::Error(reason)`. On success the relay
republishes `39000`, which the standing subscription picks up like any other state.
## Leaving
```rust
registry.update(cx, |registry, cx| registry.leave(&key, cx));
```
`leave` sends `9022`; once the relay accepts, the registry forgets the group:
unsubscribe both REQs, drop the entity and its observer, remove the `10009` entry,
delete every cached envelope for that group's `r` tag, and publish the shortened
list. A failed leave leaves everything untouched, so the group stays. There is no
separate local removal — a group someone else removed us from stays listed until
we leave it ourselves.
## GPUI integration
`init` builds the global; the registry and its groups are the only entities, and
`protocol.rs` has no GPUI dependency at all.
```rust
pub fn init(cx: &mut App) {
GroupsRegistry::set_global(cx.new(GroupsRegistry::new), cx);
}
impl GroupsRegistry {
pub fn global(cx: &App) -> Entity<Self> {
cx.global::<GlobalGroupsRegistry>().0.clone()
}
}
```
- `GroupsRegistry` holds `groups: Vec<Entity<Group>>`, the `10009` `list`, the
live `browse` results, `routes` (subscription id → `GroupKey`), one
`Subscription` per group, the fork state, and its tasks.
- `Group` owns everything the panel draws: metadata, admins/members/roles,
participants, pins, membership, the `Vec<Message>` timeline, the `previous`
window, `loading`/`loading_more`/`refused`.
- Views render `Entity<Group>` and re-read on `GroupEvent`; no protocol state
lives in a view.
### Foreground and background
One background task drains `client.notifications()` and never touches an entity;
it sends signals through an unbounded `flume` channel that one foreground
`cx.spawn` consumes, which is the only place entities change:
```
notifications() ──sig──► flume ──recv──► this.update(cx, …) ──► handle_event → reload → hydrate
```
- `handle_notifications` runs on `cx.background_spawn`; it matches
`ClientNotification::Message` and routes the message by subscription id.
- The consumer runs on `cx.spawn`; every arm is one `this.update(cx, ..)`.
- The listener and the consumer are replaced (`= None` first) on a signer change,
because a dropped `Task` cancels; that is what makes the reset clean.
- Both `save_envelope` and `load_envelopes` are `cx.background_spawn` work that
clones the `Client` in, so no database call ever runs on the foreground thread.
- NIP-46 signing is async, so all signing happens inside the background task.
### Subscriptions and routing
One `Client` and one notification stream are shared with `chat` and `community`,
so every subscription the crate owns is identified by a prefix and nothing else:
| Id | Meaning |
| --- | --- |
| `nip29-list` | the account's `10009` |
| `nip29-forks` | the admins' `10009` |
| `grp-<hash>` | a group's standing REQ (timeline + state + membership) |
| `pg-<hash>` | a "load more" page |
| `brw-<hash>` | a relay browse |
Inbound events are routed by `subscription_id` from `RelayMessage::Event`, never
by kind. That matters because `crates/chat` treats every kind-1059 event as a
NIP-59 gift wrap — anything a new subscription adds must be recognisable by id, and
the pump drops ids it did not mint. Duplicate event ids are filtered in the pump
before they reach the consumer, so a replay cannot double-hydrate.
## Not wired up yet
- **No screen consumes this crate yet.** The only references outside
`crates/nip29` are the two `nip29::init(cx)` calls, so the sidebar section, the
group panel and the join dialog are still to be built. The panel needs
`chat::Message` rendering lifted (or copied) out of `ChatPanel`: the data type
is already shared, only the row rendering is not. `crates/workspace/src/panels/browse.rs`
is the stub for browsing.
- **`9005` delete does not touch local state.** The relay stops serving the
event, but the envelope and the row stay until a reload. Dropping it needs a
filter on the target's `d` tag plus the group's `r` cache tag, and an eviction
from `messages` and the id index; nothing does that today.
- **The LiveKit response shape is a guess.** The NIP names no fields, so
`LivekitSession::parse` reads `token` (or `jwt`) and `url` (or `server_url`) and
fails loudly on anything else. Re-check it against the relay actually targeted
before building the AV UI, or the join button fails silently.
- **A relay that never EOSEs sticks a spinner.** `Browse::loading` and
`Group::loading_more` both rely on EOSE or CLOSED, and the auto-close timeout
closes the subscription with no notification at all. Bind "load more" to
`Group::loading_more()` and give the user a way out.
- **Subgroups are parsed, not assembled.** `parent`/`children` are on
`GroupMetadata` and the writes carry them; there is no tree builder, because
the tree is scoped to a relay and that is a view concern.
- **`GroupMetadata::naddr` needs a parsed metadata.** It builds from the `id` and
author the `39000` left on the struct, so a hand-built `Default` value errors
rather than minting a link that points nowhere. A group whose relay publishes
no `39000` cannot be referenced or joined at all.