load community list

crates/community/src/lib.rs

@@ -27,6 +27,7 @@ impl Global for GlobalCommunityRegistry {}
 #[derive(Debug, Clone, PartialEq, Eq)]
 enum Signal {
     Event(CommunityId),
+    List,
 }
 
 impl EventEmitter<CommunityEvent> for CommunityRegistry {}
@@ -67,6 +68,7 @@ impl CommunityRegistry {
             if event.signer_changed() {
                 this.reset(cx);
                 this.handle_notifications(cx);
+                this.subscribe_list(cx);
                 this.load(cx);
             }
         }));
@@ -76,6 +78,7 @@ impl CommunityRegistry {
                 .update(cx, |this, cx| {
                     this.handle_notifications(cx);
                     if nostr.read(cx).current_user().is_some() {
+                        this.subscribe_list(cx);
                         this.load(cx);
                     }
                 })
@@ -163,6 +166,25 @@ impl CommunityRegistry {
         cx.notify();
     }
 
+    /// Subscribe to the account's community list.
+    fn subscribe_list(&mut self, cx: &mut Context<Self>) {
+        let nostr = NostrRegistry::global(cx);
+        let signer = nostr.read(cx).signer();
+        let client = nostr.read(cx).client();
+
+        self.tasks.push(cx.spawn(async move |this, cx| {
+            let self_pk = signer.get_public_key_async().await?;
+
+            if let Err(error) = sync::subscribe_list(&client, self_pk).await {
+                this.update(cx, |_this, cx| {
+                    cx.emit(CommunityEvent::Error(error.to_string()));
+                })?;
+            }
+
+            Ok(())
+        }));
+    }
+
     /// Discover the account's communities in the local database.
     fn load(&mut self, cx: &mut Context<Self>) {
         let nostr = NostrRegistry::global(cx);
@@ -298,6 +320,11 @@ impl CommunityRegistry {
                     continue;
                 };
 
+                if sync::is_list_subscription(&subscription_id) {
+                    tx.send_async(Signal::List).await?;
+                    continue;
+                }
+
                 if event.kind != Kind::from(KIND_WRAP) {
                     continue;
                 }
@@ -313,10 +340,12 @@ impl CommunityRegistry {
         }));
 
         self.signal_consumer = Some(cx.spawn(async move |this, cx| {
-            while let Ok(Signal::Event(id)) = rx.recv_async().await {
+            while let Ok(signal) = rx.recv_async().await {
-                this.update(cx, |this, cx| this.refresh(id, cx))?;
+                match signal {
+                    Signal::Event(id) => this.update(cx, |this, cx| this.refresh(id, cx))?,
+                    Signal::List => this.update(cx, |this, cx| this.load(cx))?,
+                }
             }
-
             Ok(())
         }));
     }

crates/community/src/sync.rs

@@ -121,21 +121,135 @@ where
     Ok(state)
 }
 
-/// Discovers the current account's communities from the local database.
+/// The subscription id carrying the account's own Community List.
+pub const LIST_SUBSCRIPTION: &str = "concord/list";
+
+pub fn list_subscription_id() -> SubscriptionId {
+    SubscriptionId::new(LIST_SUBSCRIPTION)
+}
+
+pub fn is_list_subscription(id: &SubscriptionId) -> bool {
+    id.as_str() == LIST_SUBSCRIPTION
+}
+
+/// Subscribes to the account's community list.
+pub async fn subscribe_list(client: &Client, self_pk: PublicKey) -> Result<()> {
+    let id = list_subscription_id();
+    client.unsubscribe(&id).await?;
+
+    let filter = Filter::new()
+        .kind(Kind::Custom(KIND_COMMUNITY_LIST))
+        .author(self_pk);
+
+    let output = client
+        .subscribe(ReqTarget::auto(vec![filter]))
+        .with_id(id)
+        .await?;
+
+    if !output.failed.is_empty() {
+        log::warn!(
+            "community list: {} relay(s) rejected the subscription",
+            output.failed.len()
+        );
+    }
+
+    Ok(())
+}
+
+/// Discovers the current account's communities: every live membership the List
+/// carries, plus any locally-held membership the List does not mention.
+///
+/// A held membership is dropped only when the List carries a tombstone at least
+/// as new as it, because absence from the List is never a fact (§8).
 pub async fn load(
     client: &Client,
     signer: &UniversalSigner,
     self_pk: PublicKey,
 ) -> Result<Vec<CommunityState>> {
-    let mut states = store::load_states(client).await?;
+    let list = match load_list(client, signer, self_pk).await? {
+        Some(list) => list,
+        None => return store::load_states(client).await,
+    };
 
-    if let Some(list) = load_list(client, signer, self_pk).await? {
+    let mut held: BTreeMap<CommunityId, CommunityState> = store::load_states(client)
-        states.retain(|state| list.is_live(&state.id));
+        .await?
+        .into_iter()
+        .map(|state| (state.id, state))
+        .collect();
+
+    held.retain(|id, state| !retired(&list, id, state.added_at_ms));
+
+    for entry in &list.entries {
+        if !list.is_live(&entry.community_id) {
+            continue;
         }
 
-    Ok(states)
+        let fresh = match CommunityState::from_join_material(&entry.current, entry.added_at) {
+            Ok(fresh) => fresh,
+            Err(error) => {
+                log::warn!(
+                    "ignoring unreadable community {} from the list: {error}",
+                    entry.community_id.to_hex()
+                );
+                continue;
+            }
+        };
+
+        let state = match held.remove(&entry.community_id) {
+            Some(materialized) => refresh(materialized, fresh),
+            None => fresh,
+        };
+
+        store::save_state(client, &state).await?;
+        held.insert(entry.community_id, state);
     }
 
+    Ok(held.into_values().collect())
+}
+
+fn retired(list: &CommunityList, id: &CommunityId, added_at_ms: u64) -> bool {
+    list.tombstones
+        .iter()
+        .find(|tombstone| tombstone.community_id == *id)
+        .is_some_and(|tombstone| tombstone.removed_at >= added_at_ms)
+}
+
+fn refresh(mut held: CommunityState, fresh: CommunityState) -> CommunityState {
+    held.owner = fresh.owner;
+    held.owner_salt = fresh.owner_salt;
+    held.community_root = fresh.community_root;
+    held.root_epoch = fresh.root_epoch;
+    held.added_at_ms = fresh.added_at_ms;
+
+    if fresh.control_root.is_some() {
+        held.control_root = fresh.control_root;
+    }
+
+    for (epoch, address) in fresh.control_pks {
+        held.control_pks.insert(epoch, address);
+    }
+
+    held.relays = fresh.relays;
+
+    for channel in fresh.channels {
+        match held.channels.iter_mut().find(|held| held.id == channel.id) {
+            Some(held) => {
+                held.name = channel.name;
+                held.epoch = channel.epoch;
+
+                if channel.private {
+                    held.private = true;
+                    held.key = channel.key;
+                }
+            }
+            None => held.channels.push(channel),
+        }
+    }
+
+    held
+}
+
+/// Every fragment of the account's list in the local database, merged.
 async fn load_list(
     client: &Client,
     signer: &UniversalSigner,
@@ -143,14 +257,40 @@ async fn load_list(
 ) -> Result<Option<CommunityList>> {
     let filter = Filter::new()
         .kind(Kind::Custom(KIND_COMMUNITY_LIST))
-        .author(self_pk)
+        .author(self_pk);
-        .limit(1);
 
-    let Some(event) = client.database().query(filter).await?.into_iter().next() else {
+    let mut newest: BTreeMap<u64, Event> = BTreeMap::new();
-        return Ok(None);
+
+    for event in client.database().query(filter).await? {
+        let Ok(index) = cord02::list::fragment_index(&event) else {
+            continue;
         };
 
-    Ok(Some(cord02::list::parse_list_event(signer, &event).await?))
+        match newest.get(&index) {
+            Some(existing) if existing.created_at >= event.created_at => {}
+            _ => {
+                newest.insert(index, event);
+            }
+        }
+    }
+
+    let mut merged: Option<CommunityList> = None;
+
+    for event in newest.into_values() {
+        match cord02::list::parse_list_event(signer, &event).await {
+            Ok(list) => {
+                merged = Some(match merged {
+                    Some(held) => cord02::list::merge(held, list),
+                    None => list,
+                });
+            }
+            Err(error) => {
+                log::warn!("ignoring unreadable community list {}: {error}", event.id);
+            }
+        }
+    }
+
+    Ok(merged)
 }
 
 /// Rebuilds a community from the wraps already in the local database.

docs/concord-community-discovery-plan.md

@@ -76,7 +76,7 @@ Two consequences for coop:
    per-process `LOCAL_KEYS`, and never leave the machine. No equivalent exists
    anywhere in the spec. It is a local cache and must never be treated as the
    discovery source.
-2. **Discovery is: fetch my `33302` from relays → materialize a community from
+2. **Discovery is: subscribe to my `33302` → materialize a community from
    `current` join material → subscribe to its planes → fold.** The fold produces
    the authoritative state; the List only supplies the keys to start.
 
@@ -88,15 +88,15 @@ Two consequences for coop:
 | 2 | one event per fragment, `d` = index, `frags` declared | no `frags`, single event, `d` unused, `load_list` `.limit(1)` |
 | 3 | 32-byte values unpadded base64url at any depth | hex: `JoinMaterial.owner`/`control_root` (`PublicKey`/`String`), `CommunityId` serde, `ChannelGrant.key` |
 | 4 | `seed` omitted when equal to `current`; embedded snapshot omits `community_id`; `seed`'s cosmetic fields rewritten from `current` | both snapshots always serialized verbatim; `community_id` always present |
-| 5 | fetch from relays | local database only |
+| 5 | fetch from relays | local database only — **fixed in Phase C** |
 | 6 | materialize `CommunityState` from join material | no such path; only `CommunityState::from_genesis` |
 | 7 | publish the List on create/join (read-modify-write) | `build_list_event` is referenced only by tests and docs |
 | 8 | private channel keys ride in join material | `ChannelKeyRef` has no key field |
 
 Divergences 1–4 meant that even if the fetch existed, coop could neither read
-what accordion wrote nor write something accordion could read. **Phases A and B
+what accordion wrote nor write something accordion could read. **Phases A, B and
-are done**, so 1–4 and 6 are resolved; 5, 7 and 8 remain (8 only in that private
+C are done**, so 1–6 are resolved; 7 and 8 remain (8 only in that private planes
-planes are still not subscribed).
+are still not subscribed).
 
 ## Plan
 
@@ -181,35 +181,55 @@ a granted key surviving, a public grant staying keyless). In `community`,
 field's type is crate-private, so the materialization and the plane derivation
 are each proved where they live.
 
-### Phase C — fetch the List from relays, then load
+### Phase C — the List drives `load` — DONE
 
-`crates/community/src/sync.rs`
+`crates/community/src/sync.rs`, `crates/community/src/lib.rs`
 
-1. `load` becomes:
+1. `subscribe_list(client, self_pk)` subscribes to `Kind::Custom(33302)`
-   - resolve where to ask: the account's NIP-65 write relays (kind `10002`) plus
+   `author(self_pk)` under a dedicated `concord/list` subscription id, using
-     the pool's connected relays. If only the app's bootstrap relays are queried,
+   `ReqTarget::auto`. With gossip enabled, `auto` breaks the filter down by
-     a List published by another client (e.g. accordion on `relay.damus.io` /
+   author, so it queries the account's NIP-65 write relays and adds/connects
-     `nos.lol`) will simply not be found.
+   them itself — bootstrap relays alone would miss a List published elsewhere.
-   - `client.fetch_events(Filter::new().kind(33302).author(self_pk))` — one
+2. `CommunityRegistry` calls `subscribe_list` once per signer (signer change and
-     filter returns every fragment. Fetched events are persisted by the client
+   the initial defer). It is deliberately **not** called from `load`:
-     (`nostr-sdk/src/relay/inner.rs:1291`), so the database read stays valid.
+   re-subscribing on every List event would re-deliver the List and loop. `reset`
-   - merge fragments → `CommunityList`.
+   does not unsubscribe it either — `subscribe_list` replaces the subscription
-   - for each entry whose `is_live(&id)`: if a state document exists, keep its
+   itself, and a `reset`-issued unsubscribe could race the replacement and cancel
-     `heads` (the fold's authority) and refresh relays/keys from `current`;
+   discovery.
-     otherwise `from_join_material(..)`.
+3. The notification listener routes a `concord/list` event to a new `Signal::List`,
-   - `store::save_state` each result so the next `load` is warm.
+   whose consumer re-runs `load`. Community planes keep using `Signal::Event(id)`.
-2. `load_list` keeps reading `client.database()` — after the fetch it is
+4. `load_list` reads every `33302` event by `self_pk` from the database, keeps the
-   populated. It must stop using `.limit(1)`.
+   newest event per fragment index, decrypts and `merge`s them. `.limit(1)` is gone.
-3. Drop the `states.retain(..)` shape: the List is now the *source* of states,
+   An incomplete List is read normally — a missing fragment is news not yet heard.
-   not just a filter over local ones. A local state whose membership is
+5. `load` unions two sources: every live List entry (materialized with
-   tombstoned is still dropped, but a List entry with no local state now
+   `from_join_material`, or refreshed if a state document already exists) and every
-   produces one.
+   held local state the List does not mention. A held membership is dropped only
+   when a tombstone outranks its `added_at_ms`; absence from the List is never a
+   fact. Each list-derived state is `save_state`d, so the next `load` is warm.
+6. `refresh(held, fresh)` keeps the fold's authority (`heads`, `banned`,
+   `dissolved`) and the control planes it learned, and takes the List's identity,
+   relays, and channel keys. Channels are merged by id rather than replaced, so a
+   public channel the fold discovered is not shed by a List snapshot that predates
+   it.
 
-Tests (no network, `nostr-memory`): a `33302` fragment written by the account is
+**As built, deviating from the sketch above.** The plan called for
-discovered with **no** state document present; a tombstoned id is dropped; a
+`client.fetch_events(..)`; the SDK's own recommendation is to keep the request
-missing fragment leaves the rest usable. A `nostr_sdk::local_relay::LocalRelay`
+path on a subscription and read the database. This is safer than it sounds: a
-(in-process relay, public in this pinned revision) can drive the real
+relay's event is persisted at `nostr-sdk/src/relay/inner.rs:1291` **before** the
-fetch/subscribe path end to end.
+notification is emitted, so a subscription plus a database read loses nothing and
+needs no explicit save. The subscription is set up with `ReqTarget::auto` rather
+than a hand-built NIP-65 relay map, because gossip already resolves the author's
+write relays and connects them on demand.
+
+Tests (no network): a fragment in the database with **no** state document
+materializes a community and writes one; a tombstone at `u64::MAX` drops a held
+membership; a two-fragment List with only fragment 0 delivered still yields its
+membership; a held membership the List never mentions is kept alongside the
+discovered one; `refresh` keeps `heads`/`banned`/`dissolved` and both control
+planes while taking the List's keys; and the `concord/list` id is not read as a
+community subscription. Fragment events are built with `build_list_event` from a
+§8 JSON payload, so the test exercises the real decrypt-and-merge path without a
+relay.
 
 ### Phase D — publish
 
@@ -234,7 +254,9 @@ rows in the sidebar. This is the first time the path can be exercised at all.
 - `cargo test -p concord` (A, B), `cargo test -p community` (B, C, D).
 - `cargo clippy --workspace --all-targets`, `cargo fmt --all -- --check`.
 - A is provable against the spec's worked example, so it needs no relay.
-- C is provable with `nostr-memory` + `LocalRelay`, so it needs no network.
+- C is provable with `nostr-memory`: fragments are built with `build_list_event`
+  and saved as the subscription would have, then `load` reads them. No relay,
+  no `LocalRelay`.
 - E is the only step that needs real relays.
 
 ## Risks and open decisions
@@ -248,8 +270,11 @@ rows in the sidebar. This is the first time the path can be exercised at all.
   NIP-44 plaintext, which understates that by roughly a third, so the count cap is
   kept as a conservative stopgap until Phase D measures the built event and
   fragments on write.
-- **Relay selection for the fetch is the difference between finding the account's
+- **Relay selection is the difference between finding the account's List and
-  List and not.** NIP-65 write relays + pool, or a user-visible relay setting?
+  not.** Resolved in Phase C by `ReqTarget::auto`, whose gossip path resolves the
+  filter's author to their NIP-65 write relays and connects them. A List
+  published only to relays with no NIP-65 entry is still unreachable; that is a
+  user-visible relay setting if it ever bites.
 - **Private channels stay unsubscribed until `planes()` derives their address
   from the granted key** (Phase B gave `ChannelKeyRef` a home for it, but the
   discovery fix does not need it). Public discovery works regardless.

docs/concord-usage.md

@@ -455,6 +455,14 @@ single-event design — §8 has **no membership limit**, its only bound is the
 65,536-byte encoded event, and the real fix is to start a new fragment on write
 (see `docs/concord-community-discovery-plan.md`, Phase D).
 
+Discovery is a **subscription, not a fetch**: subscribe with
+`Filter::new().kind(Kind::Custom(KIND_COMMUNITY_LIST)).author(my_pk)` and read the
+fragments back out of `client.database()`. The client persists a relay's event
+before it notifies, so a subscription plus a database read loses nothing and
+needs no explicit save. Parse each event with `parse_list_event`, keep the newest
+per `fragment_index`, and `merge` them — reading an incomplete List is safe, since
+a missing fragment is only news not yet heard.
+
 ## GPUI integration
 
 `crates/concord` stays GPUI-free; the registry and sync engine live in
@@ -575,10 +583,13 @@ client.subscribe(filter).with_id(sub_id).await?;
   `CommunityEvent::Error` through `log::error!`, and its "New community" row opens
   a name prompt that calls `CommunityRegistry::create`. `create` still persists
   the genesis locally without publishing it to the metadata's relays. Discovery
-  is local-only: `load` reads the state documents already in
+  subscribes to the account's CORD-02 Community List (`33302`) under the
-  `client.database()` and never fetches the account's CORD-02 Community List
+  `concord/list` subscription id and reads the fragments back out of
-  (`33302`) from relays, so a fresh install — or one signing in as an account
+  `client.database()` — the SDK persists a relay's event before notifying, so the
-  that joined elsewhere — finds nothing and never subscribes. See
+  read is always current. A `concord/list` notification re-runs `load`, which
+  materializes a community from each live List entry (`from_join_material`) and
+  keeps any state document the List does not mention, so a fresh install — or one
+  signing in as an account that joined elsewhere — finds its communities. See
   `docs/concord-community-discovery-plan.md`.
 - **Account-key writers take any signer, not `&Keys`.** `genesis`,
   `ControlWriter`, the guestbook and chat `seal_rumor`s, the `list` builders, and