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# Community history and live sync
A community panel currently shows a short, stale slice of a channel: often only
the newest handful of wraps a relay happened to replay, no older history, no
messages for private channels, and nothing at all after a rekey. The reference
client (`soapbox-pub/armada`, `src/concord/lib/channelSync.ts` and friends) pages
history from relays into a local store, keeps a cursor per channel, and keeps the
timeline live. This document is the diagnosis and the plan to get there.
**Revision 2.** Three corrections to the first revision, all of them structural:
1. **`concord` stays a thin protocol layer.** Relay and database operations do
not belong in it. Revision 1 put the whole paged fetch — `fetch_page`,
`Window`, `WrapPage`, `Walk`, the per-page subscriptions — into
`concord/src/store.rs`, next to a local cache layer that writes to the client
database. That is now framed as the mistake it is: `concord` keeps wire
formats, crypto, and the plain community document; `community` keeps every
`Client`.
2. **One notification pump, subscriptions that stay.** `community` already has a
global relay notification handler (`CommunityRegistry::handle_notifications`).
The history path must go through it: subscribe to a filter, read the page back
from the local database, keep the live subscription alive for new data, and
let the pump — not a hand-rolled per-relay wait loop inside the protocol crate
— be the only consumer of relay notifications.
3. **Cold asks for everything, warm asks for what is new.** Opening a community
with nothing cached subscribes wide (`since = None`) and pages down; opening
it again asks only for the region since the cursor. Exhaustion still has to be
earned (§3).
And one correction to a claim in revision 1: an `auth-required` CLOSE is **not** a
failure. The SDK marks that subscription for resubscription and re-issues the REQ
under the same id once the AUTH handshake completes — for auto-closing
subscriptions too, which is what a page REQ is (`nostr-sdk/src/relay/inner.rs`
`handle_relay_message` → `MarkAsClosed`, and the auto-closing handler's
`RelayNotification::Authenticated` arm). Only `AuthenticationFailed` ends a relay's
wait, and it is reported rather than rendered as an empty channel.
Read path today (phase 1 landed the walk, phase 2a moved each layer, phase 2b
swapped the transport and put the pump in charge of settling pages):
```
CommunityPanel::load community_ui/src/lib.rs:192
-> Community::sync_channel community/src/community.rs:220
-> sync_round community/src/community.rs (purge_expired,
Window::opening)
-> history::page community/src/history.rs (one REQ per page
-> ask_page community/src/history.rs over the community's
relays, registered
in the page registry)
-> PageRegistry community/src/history.rs (EOSE / CLOSED arrive
through the pump)
-> client.database().query(filter) (the page)
-> cache::cache_rumor community/src/cache.rs
-> Community::timeline community/src/community.rs:370
-> cache::query_rumors community/src/cache.rs
-> cord03::fold concord/src/cords/cord03.rs
live wire community/src/lib.rs:309 (sync_subscriptions)
-> sync::live_filter community/src/sync.rs (both wrap kinds,
private channels,
Window::opening,
limit LIVE_REPLAY)
-> pump community/src/lib.rs:433 (routes by subscription
id, batches within
PUMP_WINDOW, settles
pages by EOSE/CLOSED)
```
## What is wrong today
| # | Finding | Status | Evidence |
| - | ------- | ------ | -------- |
| 1 | History was fetched at most once per channel, only when the cache was completely empty, so the relay round was almost always skipped. | fixed in phase 1 (`sync_channel` runs per open) | `community/src/community.rs:218` |
| 2 | That one round was one shallow page with no continuation. | fixed in phase 1 (paged walk + cursors) | `community/src/history.rs` |
| 3 | The timeline was a fixed 200-row window with no way to ask for older. | fixed in phase 1 (`timeline` + `has_more` + load-older) | `community_ui/src/lib.rs:263` |
| 4 | Cursors existed but nothing used them; no "has more" signal. | fixed in phase 1 | `community/src/community.rs:337` |
| 5 | **Private channels are never subscribed and never folded**: `planes()` skips `channel.private`, so a private channel gets no live REQ and no `cache_rumor` from the subscription. | fixed in phase 2b (`planes` derives a private channel's plane from the held key; it is subscribed, paged and folded like a public one) | `community/src/sync.rs` |
| 6 | The standing REQ asks for **kind 1059 only**, and the pump drops anything that is not 1059, so 21059 (ephemeral) wraps can never be routed even though the read path asks for both kinds. | fixed in phase 2b (`live_filter`/`plane_filter` ask for both kinds; the pump routes by subscription id and never inspects the kind) | `community/src/sync.rs`, `community/src/lib.rs` |
| 7 | A **rekey strands history**: `ChannelKeyRef` holds one epoch/key, `channel_secret` returns one plane, `sync::refresh` overwrites a held key in place, and the rekey pseudonyms are never watched. | open (phase 3) | `community/src/sync.rs:331-368`, `community/src/community.rs:199-216` |
| 8 | **"No messages yet" is three different states**: unreadable wraps are dropped silently, a failed round is logged, and the panel renders all of them as an empty room. | open (phase 4; counts already exist in `Progress`) | `community/src/community.rs:38-44`, `community_ui/src/lib.rs:594-602` |
| 9 | A new message **replaced the whole timeline and forced `scroll_to_end()`**. | fixed in phase 1 (`FollowMode::Tail`, in-place merge) | `community_ui/src/lib.rs:121`, `:364-411` |
| 10 | Backfill fetched through `client.fetch_events(..)` with `ReqTarget::auto`, i.e. every relay in the pool. | fixed in phase 1 (relay-scoped, no `fetch_events` anywhere) | `community/src/community.rs:262` |
| 11 | The local cache document is authored by a **process-random key**, so the same rumor cached in two runs is a different event id and the store keeps both copies; `fold` then re-reads all of it on every inbound wrap. | fixed in phase 2a (one fixed cache key) | `community/src/cache.rs` |
| 12 | `cache::purge_expired` is never called, so expired rows only drop at fold time, never from disk. | fixed in phase 2b (`sync_round` sweeps the channel before it starts) | `community/src/community.rs` |
| 13 | **Every relay and database operation lived in `concord`**: `fetch_page` installed its own subscriptions and read the client database, `cache_rumor`/`query_rumors`/`save_state`/`load_states` wrote and read it. Consequences: the pump could not see a page's REQ (so the panel's live view and the history path were two unrelated worlds), each page hand-rolled a per-relay notification loop, and the protocol crate could not be built or tested without a `Client`. | fixed in phase 2a (split into `concord/src/state.rs`, `community/src/cache.rs` and `community/src/history.rs`; the page REQ still waits on its own loop — §2 moves it into the pump) | `concord/src/state.rs`, `community/src/{cache,history}.rs` |
| 14 | **The fold is O(history)**: `sync::fold` re-reads every wrap in the community's planes and NIP-44-opens each one on every inbound wrap, purely to cache channel rumors and observe their authors for the member list. The live REQ replays the plane on every start, so this happens on every app run and every burst of messages. | fixed in phase 2b (channel wraps are opened once, on the way in; `fold` reads already-cached authors and times from `cache::wrapper_index` instead of opening them again) | `community/src/sync.rs`, `community/src/cache.rs` |
Findings 1-4 and 9-10 are the user-visible symptom and were phase 1; 13 is where
that work landed in the wrong crate; 5-7 are why some channels look empty forever;
8 is why a failure looks like an empty room; 11 and 14 are why the store and the
fold get slower the fuller a community is.
## What the reference client does
Observed in Armada (`src/concord/lib/channelSync.ts`, `src/concord/hooks/useChannel.ts`,
`src/wire/spec.ts`, `src/concord/hooks/useRekey.ts`):
| Mechanism | Reference detail |
| --------- | ---------------- |
| Local-first read | the query resolves on an IndexedDB read (`WINDOW_SIZE = 100` rows) and network catch-up runs behind it, so the panel never waits on relays |
| Three-pass round | **newest page** → **bridge** (`since: cursor.newest`, `until: newest.oldest - 1`, healing an offline burst larger than one page) → **older** (`until: cursor.oldest`, resumed on later rounds) |
| Page size | `BACKFILL_PAGE = 50` wraps per relay per page, `BACKFILL_MAX_PAGES = 20` per round, `LOAD_OLDER_MAX_PAGES = 6` per scroll-up |
| Cursors | `{ newest, oldest, exhausted }` per channel, persisted locally, merged monotonically (`newest` forward only, `oldest` back only, `exhausted` sticky), advanced **only** when the region is verifiably complete |
| Failure semantics | a failed relay blocks exhaustion and cursor advancement; an all-empty round is a failure, never exhaustion (otherwise a notification-only room is sealed as "exhausted" and never pulls its history) |
| Page-by-page decode | each page is decrypted and committed as it lands; a deep round paints as it goes |
| Scroll-up paging | local store first (pure re-read), relays only when the store is exhausted |
| Side events | messages and their decorations (edits/deletes/reactions) get **separate budgets** (×4) so reaction floods cannot displace rows and edits outside the row window still fold |
| Live wire | one REQ per relay with the channel's **current** stream addresses; every held epoch stays in the decode set; retired epochs are asked once more, then frozen out of the REQ |
| Rekeys | a watch on `baseRekeyGroupKey(root, id, rootEpoch + 1)` plus `CHANNEL_REKEY_LOOKAHEAD = 8` epochs of channel rekey pseudonyms; adoption clears `exhausted` and re-runs the channel's sync round |
| Polling | a scheduler re-runs a channel round when it is older than 5 minutes, at most once per 30 s |
## The flow we are converging on: subscribe, then read the database
The `Signed` app (`crates/signed_state/src`) is the model, and it maps onto what
`community` already has:
| `Signed` | coop |
| -------- | ---- |
| `Backend` owns the `Client` and runs **one** notification pump that batches relay events into `BackendEvent::NostrUpdate(Vec<Update>)` within `PUMP_DEBOUNCE = 200ms` | `state::NostrRegistry` owns the `Client`; `CommunityRegistry` runs the pump |
| `Backend::subscribe_bootstrap(filters)` / `sync_bootstrap(filter)` install the REQ; the pump delivers what relays send into the database | `CommunityRegistry::sync_subscriptions` installs the live REQ; a round installs a page REQ |
| Stores (`RepoListStore`, `ProfileStore`) subscribe to backend events and re-query **only** `client.database()`, never the network | `Community::refresh` → `community::cache` reads |
| `RefreshGate` (`running`/`dirty`, one coalesced follow-up) | `Community::{refresh_task, dirty}` and `Round{running, queued, waiters}` |
| A store never awaits a relay: it reacts to a batched update and reads the database | a round awaits its own page's EOSE (through the pump) and then reads the database |
Two consequences for this codebase, stated as rules:
- **A relay is only ever asked by a subscription.** No `fetch_events`, no
`ReqTarget::auto`, no per-relay `notifications()` loop outside the pump.
- **Every read is a database read.** Cursors, folds, timelines, member lists and
pages are computed from what the database holds after a subscription put it
there.
## The fix
### 1. `concord` keeps the protocol, `community` keeps the relays and the database
`concord` gets one rule: **no `Client`, no database, no subscription**. Its
remaining job is wire formats, crypto and the community document. Everything
that talks to a relay or the local store moves one crate up:
| Today | Target |
| ----- | ------ |
| `concord/src/store.rs`: `CommunityState`, `ChannelKeyRef`, `ChannelCursor` (+ `merge`), `from_genesis`, `from_join_material`, `apply_fold`, `floors`, `identifier`, `list_entry` | `concord/src/state.rs` — the document and its pure folds, no I/O |
| `cache_rumor`, `purge_expired`, `query_rumors`, `save_state`, `load_state`, `load_states`, `state_identifier`, `LOCAL_KEYS`, the `c`/`t`/`k`/`e` tags, `STATE_PREFIX` | `community/src/cache.rs` — the local cache and the local documents |
| `Window`, `WrapPage`, `fetch_page` (renamed `history::page`), `wrap_filter`, `ingest_page`, `auth_required`, `history_subscription`, `within`, `Walk`, `Walker` | `community/src/history.rs` — the page REQ and the walk |
| `planes`, `subscription_filter`, `subscription_id`, `community_of`, `subscribe_list`, `load`, `fold` | stay `community/src/sync.rs`, extended |
| `Signal`, `handle_notifications`, `sync_subscriptions`, `track`, `reset` | stay `community/src/lib.rs`, extended into the pump (§2) |
| The `Walk`/`serve_page` tests | move to `community/src/history.rs`; the `ChannelCursor::merge` and `from_join_material` tests stay with the document; the `load_states` test moves to `community` (it needs a database) |
Notes:
- The document module is `concord::state`; items are imported by full path
(`use concord::state::{ChannelCursor, CommunityState};`) so the separate
`state` crate keeps `state::…` for itself.
- `concord`'s dependency list shrinks: `futures` and `smol` are used only by the
relay code that moves out (`smol` stays, as a dev-dependency, for the cord
tests).
- `ChannelCursor` stays a plain data type inside `CommunityState` (it is
persisted, and its `merge` is pure). What moves out is *when* to advance it —
that is `community`'s judgement, not the protocol's.
- Two deviations from the table, both to keep the layers honest.
`STATE_PREFIX`, `state_identifier` and `CommunityState::identifier` stay in
`concord::state`: they name the document's own local key, and the document
cannot reach up into `community` to borrow them. And `community`'s `cache` and
`history` are `pub mod`, so the surface that used to be `concord::store` is
still reachable (a private module turns `purge_expired` and `load_state` into
dead code).
- `docs/concord-usage.md` documented `store::fetch_page`; it was updated in the
same change.
### 2. One notification pump, and subscriptions that stay
#### Subscription ids and their routes
| Subscription | Id | Owner | Lifetime |
| ------------ | -- | ----- | -------- |
| Community List | `concord/list` (existing) | registry | signer lifetime |
| Live planes | `<community hex>` (existing `sync::subscription_id`) | community | until the signer or the plane set changes; **kept alive** |
| History page | `concord-history-<n>` (opaque, unique) | the round | one page; auto-closes on EOSE |
| Rekey watch (phase 3) | `concord-rekey/<community hex>/<n>` | community | kept alive while the community is tracked |
`route_of(&SubscriptionId) -> Option<Route>` parses the two **standing** ids into
`Route::{List, Community(CommunityId)}`, so the pump routes an event by
subscription id and never has to guess from the event itself (which is what keeps
another crate's subscription out of a community's fold).
A page id cannot be parsed this way, and that is deliberate: a NIP-01 subscription
id is capped at 64 characters, which a community hex alone fills, so an id cannot
carry both a community and a channel. A page's id is therefore an opaque
`concord-history-<n>` and the pump resolves it through the **page registry**
instead — `PageRegistry`, a `HashMap<SubscriptionId, flume::Sender<PageReport>>`
shared between the registry and the rounds. `PageReport { relay, outcome }`
carries facts; the walk decides what they mean. A report for an id nobody is
waiting on is dropped at `debug`, which is the ordinary case when a round is
cancelled. Phase 3 can add a `Rekey` route the same way, by id.
#### The pump
`CommunityRegistry::handle_notifications` becomes the only consumer of
`client.notifications()`, and it handles the message variants it drops today
(`route` and the window loop live in `community/src/lib.rs`):
```rust
fn route(notification, pages, batch) -> Flow {
match notification {
ClientNotification::Event { subscription_id, .. } => match route_of(&subscription_id) {
Some(Route::List) => batch.list = true,
// Only the database is told; the fold reads it when the window closes.
Some(Route::Community(id)) => { batch.communities.insert(id); }
// A page's event needs no routing at all: the subscription already put
// it in the database, and the round reads it back from there.
None => {}
},
ClientNotification::Message { relay_url, message } => match *message {
RelayMessage::EndOfStoredEvents(id) => pages.deliver(&id, relay_url, Settled::Replayed),
RelayMessage::Closed { subscription_id, message }
if !auth_required(&message) =>
{
pages.deliver(&subscription_id, relay_url, Settled::Refused(message.into_owned()));
}
// auth-required: the SDK re-issues this REQ under the same id after
// AUTH, so the page keeps waiting for the resubscribed answer.
_ => {}
},
ClientNotification::Shutdown => return Flow::Stop,
}
Flow::Continue
}
```
- **Kind 1059 and 21059 both route** (finding 6); the previous revision's
"drops every non-1059" check goes away entirely.
- The window is a **fixed** `PUMP_WINDOW` (200 ms, the reference app's value) from
the first notification of a burst, not a debounce that a steady stream can keep
extending. What it produces is one `Signal::Event(id)` per community that saw an
event plus one `Signal::List` — so a burst of fifty messages costs **one** fold,
not fifty. `Community::refresh` keeps its own `dirty` follow-up.
- Page verdicts (`Message`) are delivered immediately, inside the window, so an
EOSE is never held up by a burst on another subscription.
#### The live REQ stays
`CommunityRegistry::sync_subscriptions` keeps installing one REQ per community
over `state.relays` (`ReqTarget::manual`, never `auto`), and it keeps that
subscription alive: a long-lived subscription is re-sent by the SDK after a
reconnect and after a successful AUTH, which is exactly the "resync on socket
reopen" behaviour the reference client implements by hand.
What changes is the filter: it now asks for both wrap kinds, includes private
channels (§5), and carries a **window** and a bound:
```rust
/// What a community with no history in the database asks for: everything a relay
/// stores, bounded per relay so a cold start is not a whole plane.
const LIVE_REPLAY: usize = 500;
impl Window {
/// The window a channel is opened with.
///
/// Nothing held: ask wide, the round pages down from there.
/// Something held: ask only for what is new, plus an overlap for the seam.
pub fn opening(cursor: ChannelCursor) -> Self {
match cursor.newest_ms {
Some(newest_ms) => Window {
since_ms: Some(newest_ms.saturating_sub(CURSOR_OVERLAP_MS)),
until_ms: None,
},
None => Window::default(),
}
}
}
/// The window a community's standing subscription opens with.
///
/// One REQ covers every channel, so the floor is the **oldest** held cursor:
/// starting any newer would skip a channel's new region. A channel with no
/// cursor is left to its own round. `since = None` only when nothing is held.
pub fn live_window(state: &CommunityState) -> Window {
let floor = state
.channels
.iter()
.filter_map(|channel| state.cursors.get(&channel.id)?.newest_ms)
.min();
match floor {
Some(floor) => Window {
since_ms: Some(floor.saturating_sub(CURSOR_OVERLAP_MS)),
until_ms: None,
},
None => Window::default(),
}
}
```
The floor is computed **when the REQ is installed** (on open, on a plane change,
on a signer change) and is not recomputed as cursors advance: a live REQ that is
re-subscribed on every cursor merge would replay the seam on every message, and
the region it did not cover is the round's job, not the live REQ's. Note that a
`since` bounds only the *stored replay*; live events arrive whatever it is, so a
channel with no cursor still receives new messages and gets its history from its
own round.
### 3. A channel round over page subscriptions
`Community::sync_channel(&self, channel, intent, cx)` keeps its shape and its
coalescing (`Round { running, queued, waiters }`, one round per channel, a
request that arrives mid-round re-runs it once), and the panel keeps its two
intents:
```rust
pub enum Intent {
/// Opening a channel: newest data, the bridge, then a bounded older walk.
CatchUp,
/// Scrolling up: continue older history, at most `pages` pages.
Older { pages: usize },
}
```
What changes is the transport. A page is now:
1. the round registers a `flume::Sender<PageReport>` in the page registry under
the page's id, before the REQ goes out;
2. it installs **one REQ per page** over the community's relays
(`client.subscribe(ReqTarget::manual(..)).with_id(page_id).close_on(ExitOnEOSE + PAGE_TIMEOUT)`),
after checking each relay is in the pool (the pool refuses a target it does not
hold, and would fail the whole REQ);
3. the pump delivers one report per relay that settles (EOSE, or a non-auth
CLOSED); the round waits until every relay it asked has settled or
`PAGE_TIMEOUT` passes, then unregisters;
4. it reads the page **from the database** with the same filter the REQ used.
A relay the pool does not hold is settled as refused up front rather than failing
the page: its region was never read, so it blocks exhaustion like any other dead
relay.
Rules carried over from phase 1, none of which are negotiable:
- **A page boundary is exclusive.** `until = oldest_seen_ms - 1`, so consecutive
pages never share an event and the walk terminates.
- **`exhausted` is earned.** Only `raw > 0` plus a bottomed-out page on every
relay that answered may set it. An all-empty page sets `failed`, so the next
round re-asks the same region instead of sealing the channel at "no more
history".
- **A relay that never answered** (deadline) or **refused** (any CLOSED that is
not `auth-required`) is out of the walk and blocks `exhausted`; it is counted
in `Progress.errors`.
- **`auth-required` is not a failure.** The relay stays in the walk and the page
waits for the re-issued REQ's EOSE. Only `AuthenticationFailed` settles a relay
as refused, and it is surfaced.
- **One cursor, one filter per page.** The database is not per relay, so per-relay
cursors do not exist; a relay is a source that fills the database.
- **`newest_ms` advances only on a complete round** (`!newest.failed && bridge.exhausted`),
`oldest_ms` only walks down on a complete page, and `exhausted` is cleared by a
rekey.
The cold/warm distinction is now the *window rule* rather than a special case:
| State of the channel | Window |
| -------------------- | ------ |
| no cursor, nothing cached (cold open) | `Window::opening` → `since = None`: subscribe for everything the relays have, then page down |
| cursor with `newest_ms` (warm open) | `Window::opening` → `since = newest - CURSOR_OVERLAP`: new data only |
| cursor with `oldest_ms` | `Window::older_than(oldest_ms)`: older data, on demand |
| a hole between `saved.newest_ms` and the newest seen | `Window::between(..)`: the bridge |
So an open does two things, and they follow the same rule: it makes sure the live
REQ is installed — wide when nothing is held, which is where "subscribe to get all
data" comes from — and it runs a round whose newest pass asks only for the region
the live REQ did not already cover (a warm open therefore replays nothing: the
REQ is already streaming).
And the passes fall out of that rule:
- **Newest pass** (`CatchUp`): one page at `Window::opening(saved)`. Cold, this is
"get all data"; warm, this is "get only new data".
- **Bridge**: while the previous page was *full* and still above
`saved.newest_ms`, keep walking down with `until = oldest - 1`, bounded by
`CATCH_UP_PAGES`. A short page ends it, which is what lets `newest_ms` advance.
- **Older pass**: resume at `saved.oldest_ms.or(oldest_seen)` and walk down,
bounded by `CATCH_UP_PAGES` on a catch-up and `LOAD_OLDER_PAGES` on a scroll-up.
Sizes stay the reference numbers: `PAGE_WRAPS = 50`, `CATCH_UP_PAGES = 20`,
`LOAD_OLDER_PAGES = 6`, `CURSOR_OVERLAP = 60s`.
Known limitation, unchanged and deliberately deferred: the bridge is bounded by
`CATCH_UP_PAGES`, so an offline burst larger than `CATCH_UP_PAGES * PAGE_WRAPS`
(1,000 wraps) is not repaired by one round and does not heal later (the bridge
restarts from the same point). Fixing it needs a fourth cursor field recording how
far a partial repair walked. One cheap improvement belongs in phase 2b: skip the
older pass entirely when `saved.exhausted` is already set.
### 4. The read path
Unchanged from phase 1, moved intact:
```rust
pub struct Timeline {
/// Oldest first, ready for a bottom-aligned list.
pub messages: Vec<ChatMessage>,
pub has_more: bool,
}
pub fn timeline(&self, channel: &ChannelId, before_ms: Option<u64>, limit: usize, cx: &App)
-> Task<Result<Timeline>>;
```
- Reads `limit + 1` rows to compute `has_more`, plus the side-event budget over
the same span (`SIDE_EVENT_FACTOR = 4`), folds with `cord03::fold` (unchanged —
it already resolves edits, deletes and reactions), reverses, returns.
- `TIMELINE_PAGE = 100` is the first paint; older history stays on disk and comes
back when the user scrolls up.
- The panel's only read is `timeline`.
### 5. Live completeness
- **Private channels get a plane.** `sync::planes` derives it from the held key
(`channel_secret` already knows the rule); a private channel is subscribed and
folded exactly like a public one (finding 5).
- **Both wrap kinds.** The filter asks for `KIND_WRAP` and `KIND_WRAP_EPHEMERAL`
in the live REQ and in every page REQ, and the pump routes both (finding 6).
- **Community relays only.** The live REQ and every page REQ use
`ReqTarget::manual` over `state.relays`; a relay outside the community is never
asked (finding 10).
- **Expired rows are swept** on the open and round cadence with
`cache::purge_expired` (finding 12).
- **A stable cache key.** One local signing key persisted in the config dir
replaces `LazyLock::new(Keys::generate)` (finding 11); the same rumor cached
twice then has one addressable coordinate, so `save_event` replaces its
predecessor instead of adding a copy per app run.
### 6. Held epochs and rekey adoption (phase 3)
The client has to be able to read the epochs it is supposed to read, and learn
the next ones:
- `ChannelKeyRef` gains
`#[serde(default, skip_serializing_if = "Vec::is_empty")] priors: Vec<HeldKey>`
where `HeldKey { epoch: Epoch, key: [u8; 32], retired_at: Option<u64> }`, and
`CommunityState` gains the same shape for roots (`HeldRoot { epoch, key,
`control_pk, retired_at }`). `channel_secret` returns every held epoch,
`history::page` already takes `&[(Epoch, [u8; 32])]`, and `sync::refresh` stops
overwriting a held key in place and pushes the old one onto `priors`.
- **`retired_at` is a read cutoff.** The reference retires the key a rotation
steps off **at the rotation's own publish time**: nothing sealed under that key
after it is read again. The read side needs the same floor: a wrap at epoch *e*
whose `created_at` is past `priors[e].retired_at` is refused, at both the page
and the fold.
- **The rekey watch is a subscription too**: one long-lived REQ per community over
its relays for `authors(rekey pseudonyms)`, `kinds([KIND_WRAP])`, where the
authors are `cord06::rekey_group(RekeyScope::Base, held_root, id, epoch + 1)`
and — for every private channel and **every held root** (a Refounding seals
channel rekeys under the prior root) —
`cord06::rekey_group(RekeyScope::Channel(channel), held_root, channel, epoch)`
for `epoch in held_epoch + 1 ..= held_epoch + REKEY_LOOKAHEAD` (`8`).
- Adopt strictly, one epoch at a time, off the key actually held:
`cord01::open_wrap` → `cord06::parse_rekey_chunk` → `cord06::collect_rotations`
→ `is_complete` → `rotation.continuity(held_epoch, held_key)` must be `Extends`
(`Gap` is fetched, never waived; `Fork` resolves with `cord06::fork_winner`'s
lowest-key rule) → `cord06::find_my_blobs` + `open_blob` → `KeyDelivery`.
- Persist per delivery, then **re-install the subscription** (the plane set
changed), clear that channel's `exhausted`, and run a `CatchUp` round for it.
- Two terminal states, both persisted and both shown, never rendered as an empty
timeline: **removed** (`cord06::am_i_removed` on a complete rotation at/after
my join whose rotator outranks me — `added_at_ms` and `rekey_authorized`
already carry the comparison) and **stranded** (a complete rotation ahead of my
epoch that predates my join and carries no blob for me, which says the invite
link is out of date).
### 7. Honest states (phase 4)
- `Progress` already carries `fetched`, `opened`, `exhausted`, `failed`, `errors`;
the fold reports what it could not open; `Snapshot` carries those counts.
- `CommunityEvent` gains "history exists that we cannot read" and "the last round
failed", and the panel renders "N messages here can't be read yet — the channel's
key for epoch 3 is missing" or "Couldn't reach the community's relays" with a
retry, instead of "No messages yet" (finding 8).
### 8. `community_ui`: reach the older rows
Landed in phase 1, unchanged by the re-layering: per-channel `rows`, `has_more`,
`loading`, `FollowMode::Tail` instead of `scroll_to_end()`, load-older from the
scroll handler plus an always-index-0 "Load earlier messages" row, prepend via
`splice(1..1, n)`, append via `splice(at..at, n)`, and in-place merging unless the
newest window no longer reaches the rows on screen.
Two rules survive, both about GPUI rather than about history:
- **Never `set_follow_mode` or force a scroll position inside a scroll-handler
callback** — the list holds its state borrowed while it invokes the handler, so
touching `ListState` there panics. `load_older` is written to avoid it.
- The panel's `Intent::{CatchUp, Older}` calls do not change: the round they
trigger is now subscription-driven, which is invisible to the list.
Still deferred: per-channel timeline state (switching back re-reads), and the
`MAX_TIMELINE_ROWS` trim (trimming the oldest rows fights `load_older`, which
prepends at the same end — the reader would oscillate).
### 9. The fold stops being O(history) (phase 2b) — **landed**
`sync::fold` used to open every wrap in the community's planes on every inbound
wrap: channel wraps were re-opened only to `cache_rumor` them again and to observe
their authors, which the database already holds as decoded rows (the cached row
carries the author in a `p` tag, the message time in `created_at`, and the wrap it
came from in an `e` tag). Finding 14.
What landed is smaller than the first sketch and needs no new queue:
- `cache::wrapper_index(client, channel)` reads the cached rows back as
`EventId -> Observed { author, at_ms }`, keyed by the wrap they were opened from.
- `fold` opens a channel wrap only when its id is **not** in that index; an
already-cached wrap is observed from the row instead. A wrap is therefore opened
**once, on the way in** — by a round for a page, by the first fold after it
arrives for the live wire — and never again.
- The control and guestbook planes are still read from wraps (they are small, and
`cord02::fold_control` is a fold over all editions by construction).
The fold still *reads* every wrap from the database (`plane_filter`, which is now
its own unbounded filter separate from the live one); what it no longer does is
NIP-44-open them all. The plan's per-channel work queue in the pump turned out to
be unnecessary for that: the first fold after a live wrap already opens exactly
the uncached wraps.
## Order of work
### Phase 2a — move the code (no behaviour change) — **landed**
1. `concord/src/store.rs` split into `concord/src/state.rs`, `community/src/cache.rs`
and `community/src/history.rs` per the table in §1; call sites updated
(`community/src/sync.rs`, `community/src/community.rs`, `community/src/lib.rs`,
and the `cord02` test's `crate::store::CommunityState`). `fetch_page` is now
`history::page`.
2. The local cache key is stable (`cache::LOCAL_KEYS` is one fixed secret, not a
per-process `Keys::generate`), so caching a rumor twice leaves one row.
`cache.rs` carries the new `caching_the_same_rumor_twice_leaves_one_row` test.
3. `docs/concord-usage.md` updated; `concord` dropped `futures` and `nostr-memory`
and demoted `smol` to a dev-dependency; `community` gained `futures` and `smol`.
4. Gate, all green with the phase-1 transport still in place: `cargo test -p
concord -p community` (50 + 14), `cargo clippy -p concord -p community -p
community_ui --all-targets`, `cargo +nightly fmt --all --check` (no diff in the
touched files), `cargo check -p workspace --all-targets`. No behaviour changed
beyond item 2.
### Phase 2b — subscribe, then read the database — **landed**
1. The pump (§2): route by subscription id for events, EOSE and CLOSED; batch
within `PUMP_WINDOW`; both wrap kinds; `auth-required` never a failure.
2. Page REQs (§3): the round registers a `PageReport` channel, installs one REQ
per page over the community's relays, awaits the pump's reports with
`PAGE_TIMEOUT`, reads the page from the database, and keeps the walk's rules
(`exhausted` earned, all-empty is `failed`, `newest_ms` only on a complete
round, skip the older pass when `saved.exhausted`).
3. The live REQ (§2, §5): both kinds, private channels, the window rule with
`LIVE_REPLAY = 500`, kept alive across reconnects.
4. `cache::purge_expired` on the round cadence (every round is an open).
5. The fold issue (§9).
6. Gate: `cargo test -p concord -p community` (50 + 23),
`cargo clippy -p concord -p community -p community_ui --all-targets`,
`cargo +nightly fmt --all --check`, `cargo check -p workspace --all-targets`;
plus the phase-1 manual bar and a dev-relay check that a warm open sends one REQ
per relay carrying a `since`, and a cold open sends one with no `since` and pages
down.
Three deviations from the revision-2 sketch, each forced by a constraint it did
not account for:
- **A page id is opaque and resolved through a registry, not parsed.** A NIP-01 id
is capped at 64 characters and a community hex fills it, so
`concord-history/<community>/<channel>/<n>` could never be sent. `route_of`
therefore only parses the two standing ids, and `PageRegistry` maps a page id
back to the round waiting on it.
- **The live window is per community and aggregates cursors.** There is one REQ
per community, so `Window::opening(cursor)` applies to a channel's newest pass
while `sync::live_window(state)` derives the community floor as the *oldest*
held cursor (a channel with no cursor forces `since = None`).
- **The fold needs no pump work queue.** Skipping already-cached wraps through
`cache::wrapper_index` already makes a wrap open once, on the way in, because the
first fold after a live wrap is the one that opens it. See §9.
Also landed as the cheap win §3 promised: the older pass is skipped entirely when
`saved.exhausted` is already set.
### Phase 3 — epochs and rekeys
§6: `HeldKey`/`HeldRoot` + `priors`, `retired_at` as a read cutoff, the rekey
watch over every held root, strict one-epoch-at-a-time adoption, re-subscribe +
`CatchUp` after a delivery, removed versus stranded states.
### Phase 4 — honest states and polish
§7 (empty/unreadable/failed in the panel, using the counts that already exist),
round progress in the UI, the `MIN_ROUND_INTERVAL = 30s` / `STALE_AFTER = 5min`
scheduler, and optional NIP-77 catch-up (`client.sync(filter)` where a relay
supports negentropy; "negentropy unsupported" means "fall back to the paged
walk", never "exhausted").
Each phase leaves the client consistent on its own. Phase 2a was invisible; phase
2b is what makes "open a community" a subscription and a database read. Phase 3
(§6) is next: it is what keeps a rekey from stranding history.
## Phase 1 status (landed)
What phase 1 delivered, and what phase 2 replaces:
- `Window`, `WrapPage`, `history::page`, `Walk`/`Walker`, the paged walk with an
exclusive page boundary, `ChannelCursor` + monotonic `merge` persisted in
`CommunityState.cursors`, `Community::sync_channel`/`timeline`, `cache_rumor`
counting what opened, and the panel's load-older/follow-the-tail work. All of
that survives; phase 2a moved it and phase 2b swaps its transport.
- **`fetch_events` is gone.** Phase 1 already replaced it with
subscribe-then-read-the-database: each page subscribed every answering relay to
one filter (`relay.subscribe(..).close_on(ExitOnEOSE + PAGE_TIMEOUT)`), waited
for that relay's `EndOfStoredEvents(id)`, then read the page with
`client.database().query(filter)`. Revision 2's correction is **where** that
lives (`community`, not `concord`) and **who** watches the notifications (the
pump, not a loop inside a page).
- `auth-required` was already excluded from the failure set in code, but
revision 1's prose described it wrongly ("ends that relay's wait as a failure
... the next round retries"). The SDK re-issues the REQ under the same id after
AUTH — for auto-closing subscriptions too — so the honest statement is: the
relay stays in the walk and the page waits for its resubscribed answer.
- Held epoch handling and rekeys are still open in §6, and honest empty states in
§7. Private planes, the second wrap kind, the expired-row sweep, the stable
cache key and the fold cost were open before phase 1 and are now landed (§5,
§9).
## Tests
Following the existing `MemoryDatabase` and `Walk`/`serve_page` test style. The
2b pieces are covered by unit tests that need no relay; the rows still marked
outstanding are the ones that need a GPUI harness or two live accounts.
- The walk: `history::page` continues past a page whose wraps none of them open;
`exhausted` requires a short page *after* history; an all-empty round is
`failed` and the next round re-asks the same region; `until` is exclusive and
the walk terminates; a channel that already holds its newest page still pages
older history; the bridge heals a hole; history pages across a rekey using
retained prior keys. (Phase 1 landed the `Walk` half; the page-REQ half needs a
relay.)
- The pump — **landed in 2b** (`community/src/lib.rs` tests): an
`EndOfStoredEvents(id)` settles exactly the page that owns `id`; a non-auth
CLOSED settles its relay as refused; an `auth-required` CLOSED settles nothing;
a page's event routes to nothing; a burst collapses to one signal per
community; a shutdown stops the pump.
- The windows — **landed in 2b**: `Window::opening(default)` has no `since`;
`Window::opening(saved)` starts at `newest - CURSOR_OVERLAP`; `Window::older_than`
never includes the boundary event; `sync::live_window` is wide cold and resumes
at the oldest held cursor warm.
- The subscription plan — **landed in 2b**: a private channel's plane appears when
the key is held and is absent when it is not; `plane_filter` asks for both wrap
kinds and addresses every readable plane. The page-REQ half (a warm open's REQ
carries a `since`, a cold open's does not) still needs a dev relay.
- The page registry — **landed in 2b**: a page that has already unregistered
receives nothing.
- The read path: the side-event budget folds an edit/delete/reaction older than
the row window onto its message.
- The fold: a new live wrap costs one decrypt, and a fold over a community with
5,000 cached rows does not re-open them. (The skip is in place and structurally
tested by `wrapper_index`; counting decrypts needs a harness.)
- A stable cache key: caching the same rumor twice leaves one row (the phase-1
regression that duplicates a community's history per app run). **Landed in 2a.**
- GPUI (`TestAppContext`): prepending older rows preserves the scroll anchor; a
live message does not scroll a reader who is scrolled up; `has_more == false`
disables the load-older row. (No GPUI test harness exists in the repo yet.)
- Manual runs: two accounts, a channel with more than 200 messages, one account
offline long enough to miss a full page, one private channel, one rekey. The
acceptance bar is the reference behaviour: open a channel cold and see history
arrive in pages without touching the scrollbar, reopen it and see one REQ with a
`since` instead of a replay, and see the other account's message appear without
a reload.
## Out of scope
Unread badges, notifications, message threads, pins, typing indicators and
presence (21059 wraps are wired for routing here, not for those features), file
and media rendering, moderation actions, and the community-management surfaces.
`crates/chat`'s DM path shares none of this code and is not touched; a later
change can lift the page walk/cursor into a shared module if DMs grow the same
paging.
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