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coop/docs/community-history-sync-plan.md
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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.
**Revision 3.** One more correction, from a review of what revision 2 landed:
4. **Time is a type, not a `u64` with the unit in its name.** The read path held
three different units in the same `u64`: `HeldKey`/`HeldRoot.retired_at` held
seconds (but were compared with a `Timestamp` through `.as_secs()`),
`ChannelCursor` held milliseconds that were only ever seconds multiplied by a
thousand, and `CommunityState.channel_cuts` held epochs. Every filter boundary
divided by a thousand on the way out. §10 types the time fields (`Timestamp`,
`Epoch`) and leaves a millisecond only where a millisecond is real.
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, phase 3 added
the rekey watch and held epochs, phase 4 made an empty or unreadable room say so,
phase 5 typed the times they all compare):
```
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)
-> rekey::watches community/src/rekey.rs (base next epoch +
a channel window per
held root)
-> pump community/src/lib.rs:433 (routes by subscription
id, batches within
PUMP_WINDOW, settles
pages by EOSE/CLOSED)
-> rekey::adopt community/src/rekey.rs (reads the rekey wraps
back from the database,
adopts one epoch at a
time)
scheduler community/src/lib.rs (one tick per
-> Community::tick community/src/community.rs MIN_ROUND_INTERVAL;
a channel that has
passed STALE_AFTER
re-folds and re-rounds)
```
## 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. | fixed in phase 3 (`priors`/`held_roots` + `retired_at`, the rekey watch, and strict one-epoch-at-a-time adoption) | `community/src/rekey.rs`, `concord/src/state.rs` |
| 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. | fixed in phase 4 (`WrapPage`/`Progress`/`Snapshot` carry `unreadable`, the community exposes `progress`/`unreadable`/`missing_key`/`channel_removed_at`/`removed_at`/`stranded`, and the panel renders a reason plus a retry instead of an empty room) | `community/src/community.rs:46-53`, `community_ui/src/lib.rs:235` |
| 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 | `rekey-<community hex, first 32>` (opaque) | 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 added the `Rekey` route the same way, through a parallel
`rekey::WatchRegistry` that maps an opaque `rekey-<32 hex>` id back to its
community: the whole id is sent to the relay, so a page's rule applies — an id
cannot carry a community hex and stay within the cap.
#### 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 {
Some(newest) => Window {
since: Some(newest - CURSOR_OVERLAP),
until: 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)
.min();
match floor {
Some(floor) => Window {
since: Some(floor - CURSOR_OVERLAP),
until: 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 - 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` advances only on a complete round** (`!newest.failed && bridge.exhausted`),
`oldest` 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` (warm open) | `Window::opening` → `since = newest - CURSOR_OVERLAP`: new data only |
| cursor with `oldest` | `Window::older_than(oldest)`: older data, on demand |
| a hole between `saved.newest` 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`, keep walking down with `until = oldest - 1`, bounded by
`CATCH_UP_PAGES`. A short page ends it, which is what lets `newest` advance.
- **Older pass**: resume at `saved.oldest.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 one per held epoch
(the current key plus every `priors` entry), and a public channel one per held
root, so a rotation never blanks a plane; 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) — **landed**
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<Timestamp> }`, 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).
**What landed.** `HeldKey { epoch, key, retired_at }` and
`HeldRoot { epoch, key, control_pk, retired_at }` live in `concord::state`;
`ChannelKeyRef` gained `priors` and `CommunityState` gained `held_roots`,
`channel_cuts`, `removed_at` and `stranded`. `CommunityState::roots()` and
`held_keys(channel)` are the read surface: a private channel returns its current
key plus every prior, a public channel one entry per held root. `sync::planes`
derives a plane for each, `history::page` takes `&[HeldKey]` and refuses a wrap
sealed under a retired key after its cutoff, and `sync::fold` applies the same
cutoff. `sync::refresh` no longer overwrites a held key in place — it pushes the
superseded one onto `priors` — and a recorded `channel_cuts` entry keeps a stale
grant from merging a removed channel back.
The wire side is `community/src/rekey.rs`: `watches(state)` builds the base
next-epoch address plus a `1..=8` channel window under every held root,
`watch_filter` is the one standing REQ over the community's relays, and `adopt`
reads the delivered wraps back out of the database and walks each scope forward.
`CommunityRegistry` installs the watch beside the live REQ when a community's
plane set changes, routes its events to `Signal::Rekey` through the pump, and
`Community::merge_adoptions` folds the result in, persists it, clears the moved
cursors' `exhausted` verdicts, and runs a `CatchUp` for the active channel.
Three deviations from the sketch above, all of them smaller than planned:
- **The rekey watch is one subscription per community, not per scope.** The base
and every private channel ride the same `authors` filter; the wraps are
addressed by pseudonym, so one REQ covers them all and one `watch_filter`
rebuild covers every adoption. The id is opaque (`rekey-<32 hex>`) and resolves
through `rekey::WatchRegistry` for the same 64-character reason a page id does.
- **A removal is judged without continuity, a strand with it.** Adoption requires
`Extends`; the removal/strand decision considers every complete authorized
rotation at the target epoch **except** one whose `prevcommit` forks (which is
neither, and acting on it is how a member ends up on a fork). A member who
missed a link is still removable — the reference's own channel watcher treats
"past my epoch" as the removal test.
- **Adoption chains within one pass.** `walk` loops `held + 1` while each step is
adoptable, so a member who missed several rotations catches up in one database
read instead of one pass per poll. The lookahead window is what feeds it.
#### The writer (phase 6) — **landed**
Phase 3 gave the client a receiver; phase 6 gives it a hand. `rekey::rotate`
builds the rotation from the key the client actually holds and publishes it, and
`Community::rotate` is the entry a moderation surface will call:
- **One plan, drawn in the protocol crate.** `cord06::plan_rotation(scope, epoch)`
mints what the rotation delivers — a `Refounding` (new root and control pair)
for a base scope, a fresh key for a channel — beside `plan_refounding`, which is
now the base arm of it. No caller ever holds a rotation secret before the
rotation exists.
- **Authority first, and the same authority the receiver applies.** `Rewrite::authorized`
runs `cord06::rekey_authorized` under `permissions(scope)` — the same list
`adopt` now walks with, shared instead of written twice — so the client cannot
publish a rotation it would not itself adopt. `Community::rotate` adds the three
states the role fold cannot see: a removal, a strand and a ban.
- **One blob per recipient, and the rotator is one of them.** A rotation that
delivered no blob to its own rotator would strand them, so the writer refuses
one. Staff get the new Control Plane root beside the key, everyone else gets the
key alone.
- **A refounding carries its heads.** `carry_heads` reads the control editions
back out of the store, picks the ones the settled floors name, and `compact`s
them onto the new epoch's groups. Without it the new Control Plane starts empty
and the next reader that does not hold the old root folds no roles, metadata or
banlist at all. (`compact` re-signs nothing, so this only works on the plaintext
seals the Control Plane already uses.)
- **Then it adopts itself, through the ordinary receiver.** The chunks are saved
into the local database as they are sent, so `Community::rotate` calls the same
`rekey::adopt` the watch calls instead of adopting by construction: one path for
every rotation, whoever wrote it. Publish failures are logged per relay and do
not change the held state, so a rotation that only reached some relays still
leaves this client consistent — which is the same asymmetry the reference has.
- **The receiver now keeps the signing root it is handed.** `BaseAdoption`
carries the delivered `control_root` through to `state.control_root`; before
this, a refounding's root was dropped at the receiver and a staff member went on
signing under the epoch they had left.
What is still not here: the trigger. Kicking a member, choosing a channel's
remaining audience, and rendering any of it is the moderation and
community-management surface §8 keeps out of scope, so `Community::rotate` is an
API with no caller in the app yet — and `Rewrite.recipients` is the caller's to
name, because a private channel's audience is in each member's own invite and not
in the local state.
### 7. Honest states (phase 4) — **landed**
"No messages yet" is a claim, and finding 8 is that the client made it in three
situations it could not tell apart. The rule is that a room only says it is empty
when it *knows* it is empty; otherwise it says what is actually wrong.
What is carried out of the read path:
- `history::WrapPage.unreadable` counts the wraps a page reached under a held
plane that no held key could open — sealed past the cutoff a rotation set on the
key that reads them, or bound to another channel. `Walk`'s count is the page's;
`Progress.unreadable` sums the pages of a round.
- `sync::Snapshot.unreadable` is the same count over the whole store, per channel,
so a wrap is counted whether it arrived on a round or on the live wire. A wrap
already opened on the way in stays readable through its cached row and is never
counted.
- `Community` keeps the last completed round's `Progress` per channel and the
`unreadable` counts, merged monotonically: an unreadable wrap stays unreadable,
so a later quiet round cannot erase the count.
What the community answers:
- `progress(channel)`, `unreadable(channel)`, `missing_key(channel)` (a private
channel we know and hold no key for, with the epoch), `channel_removed_at(channel)`
(a channel rotation's cut), plus the phase-3 `removed_at()` and `stranded()`.
- `due(channel)`: whether an automatic catch-up is worth asking for yet.
What the panel renders, in precedence order, instead of an empty room:
| State | Rendered |
| ----- | -------- |
| `stranded()` | "This invite is stale — the community has rotated past the epoch it names" |
| `removed_at()` | "You were removed from this community at epoch N. Its history stays readable" |
| `channel_removed_at()` | "A rotation removed you from this channel at epoch N" |
| `missing_key()` | "Messages here can't be read yet — this channel's key for epoch N is missing" |
| `progress.failed && progress.errors > 0` | "Couldn't reach the community's relays" + **Retry** |
| `unreadable(channel) > 0` | "N messages here can't be read yet — no key we hold opens them" |
| otherwise, no rows | "No messages yet" |
The notice replaces the empty state, and sits as a one-line strip above the rows
when there are rows, so a stale room says it may be stale rather than looking
complete. Only *Retry* is actionable, and it runs the round directly — the
`MIN_ROUND_INTERVAL` gate below only paces automatic rounds.
One of those states is about writing, not reading. A room a rotation removed us
from, a channel it cut, a key we never held, or a stale invite all mean the same
thing at the wire: `channel_secret` is `None`, so a wrap sealed now would be
sealed under a root nobody who rotated reads. `Community::send` therefore refuses
in those cases (§6's deferral, closed), and the panel disables the send button
while the notice says why. A channel that is merely unreachable or partly
unreadable still writes: reading and publishing are separate paths.
Two `CommunityEvent`s carry the same news to any other view: `Failed(id)` (the
last round could not reach the relays) and `Unreadable(id)` (history here that no
held key opens). `Failed` replaces the `Error(..)` toast a failed round used to
raise, because the panel now says it in place.
### 7b. The round scheduler (phase 4) — **landed**
Two constants in `community/src/community.rs`:
- `MIN_ROUND_INTERVAL = 30s` — `Community::due(channel)` is false while a round
for that channel ran inside the window. The panel's automatic round on open (and
on a channel switch) is what consults it, so opening a channel twice in a breath
asks the relays once. A round for `Older`, a retry, and the catch-up a rekey
adoption triggers all bypass it — only the automatic open is paced.
- `STALE_AFTER = 300s` — `Community::tick` re-folds, and re-rounds the active
channel, once a channel that has been *synced before* has gone unsynced that
long. A channel with no recorded round is left alone, so a community nobody has
opened costs nothing, and a quiet one asks its relays at most once per five
minutes.
`CommunityRegistry` owns one task for this, armed beside the pump and the signal
consumer in `handle_notifications` and cleared in `reset`, so a signer change
stops it and re-arms it.
### 7c. Not done in phase 4
- **NIP-77 (`client.sync`) catch-up.** Still skipped deliberately. A negentropy
reconciliation is a second way to ask the same question, and getting its
"unsupported"/partial answers right — never reading one as `exhausted` — is its
own piece of work with its own failure modes. The paged walk is the fallback the
plan already specifies, so nothing here blocks on it.
- **The fold's control and guestbook planes** keep logging an unopenable wrap
rather than counting it: `Snapshot.unreadable` is per channel, and there is no
honest place yet to render "the community's own metadata is unreadable".
### 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 list: the round
they trigger is subscription-driven, which is invisible to it. Phase 4 added one
gate in front of the `CatchUp` one — `due()` — and it only paces how often the
relays are asked, not what the list does with an answer.
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.
### 10. Time is a type: `Timestamp`, not padded milliseconds (phase 5) — **landed**
The read path compared times through a bare `u64` in three units, and each
boundary paid for the confusion:
| Value | Held | What it cost |
| ----- | ---- | ------------ |
| `HeldKey.retired_at`, `HeldRoot.retired_at`, `Plane.retired_at` | seconds | compared with `wrap.created_at.as_secs()`, written as `at_ms / 1000` |
| `ChannelCursor.newest_ms`/`oldest_ms`, `WrapPage`, `Window`, the `Walk` bounds | milliseconds, always `secs * 1000` | `* 1000` on every accepted page, `/ 1000` on every filter |
| `CommunityState.channel_cuts` | epochs | `Epoch` unpacked to `u64` and rewrapped at the boundary |
| `added_at_ms`, a rumor's `at_ms` | milliseconds, genuinely | — |
What landed:
- `HeldKey`/`HeldRoot.retired_at`, `ChannelCursor.{newest,oldest}`,
`WrapPage.{newest,oldest}`, `Plane.retired_at`, `Window.{until,since}` and the
`Walk` bounds are `Timestamp`s. A window bound and a wrap's `created_at` are now
the same type, so `read_under` and `Plane::accepts` compare them directly,
`wrap_filter`/`live_filter` hand them to `until`/`since` unchanged, and the
page's exclusive boundary is written `oldest - 1` instead of `oldest_ms - 1`
truncated back to seconds.
- `CURSOR_OVERLAP` is a `Duration` (`60s`), not `60_000`, so
`newest - CURSOR_OVERLAP` reads as what it is.
- `channel_cuts` is `BTreeMap<ChannelId, Epoch>`, which is what
`rekey::Adoptions::cuts` already carried.
- **The two millisecond fields stay milliseconds.** A rumor's time is genuinely
finer than a wrap's second-granular `created_at`: CORD-01 carries the sub-second
offset in an `ms` tag and `resolve_ms_strict` puts it back, so a reader's
`at_ms` and `timeline`'s `before_ms` keep it. The cord02 list document's
`added_at`/`removed_at` keep it too, and not merely for fidelity: `added_at` is
an ordering key judged against a tombstone's `removed_at` under a strict `>`,
so narrowing both to seconds could tie a rejoin with the leave that preceded it.
- **A stored cursor is retired, not reinterpreted.** A document written when the
boundaries were milliseconds would deserialize into a `Timestamp` far in the
future, and its `exhausted` would then wedge the older pass for good. The map's
serde key changed (`cursors` → `channel_cursors`), so such a record is dropped
and the next round rebuilds the cursor from the wraps it reads;
`a_cursor_stored_in_the_old_unit_is_dropped_rather_than_reinterpreted` pins
both halves of that. `retired_at` needed no such treatment, because it was
already written in seconds.
No behaviour changes with it: the walk paged the same regions before and after,
because every millisecond it held was a second multiplied by a thousand.
## 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 — **landed**
1. The document (§6): `HeldKey`/`HeldRoot`, `ChannelKeyRef.priors`,
`CommunityState.held_roots`/`channel_cuts`/`removed_at`/`stranded`, and the
`roots()`/`held_keys()` read surface.
2. The read cutoff: `history::page` takes `&[HeldKey]` and refuses a wrap sealed
under a retired key after the rotation's publish time; `sync::fold` applies the
same rule from the channel's `priors`.
3. `sync::planes` derives planes from every held channel epoch and every held
root; `sync::refresh` preserves priors and honors recorded channel cuts.
4. The rekey watch and adoption (§6), `community/src/rekey.rs`, wired through the
pump's `Signal::Rekey` and a `WatchRegistry`.
5. Gate, all green: `cargo test -p concord -p community` (50 + 29),
`cargo clippy -p concord -p community -p community_ui --all-targets`,
`cargo +nightly fmt -p concord -p community -p community_ui --check`,
`cargo check -p workspace --all-targets`.
### Phase 4 — honest states and polish — **landed**
§7, §7b: the read path counts what it cannot open (`WrapPage`/`Progress`/
`Snapshot` `unreadable`), the community exposes the honest read surface
(`progress`, `unreadable`, `missing_key`, `channel_removed_at`, `due`, beside the
phase-3 `removed_at`/`stranded`), the panel renders a reason and a retry instead
of "No messages yet", the round scheduler paces automatic rounds
(`MIN_ROUND_INTERVAL`) and repairs a stale one (`STALE_AFTER`), and §6's
send-time gap is closed: a removed, cut, keyless or stranded room holds no write
key.
Gate, all green: `cargo test -p concord -p community` (50 + 32),
`cargo clippy -p concord -p community -p community_ui --all-targets`,
`cargo +nightly fmt -p concord -p community -p community_ui --check`,
`cargo check -p workspace --all-targets`.
Five recorded deviations:
- **A one-line strip above the rows, not only an empty state.** §7's finding is
about the empty room, but the stale case — rows on screen, relays unreachable or
history unreadable — is the same lie in a quieter form, and it is the one the
original report is actually about ("not full of messages and latest data"). A
failed round's strip is transient: the next round that succeeds replaces
`progress` and clears it. An `unreadable` count is monotone by design, because a
wrap no held key opens stays unopened.
- **`Failed` replaces the `Error(..)` toast** on a failed round rather than
accompanying it, so the panel is the single place that reports it.
- **`due()` gates the panel's automatic round, not `sync_channel`.** The plan
named the interval but not the seam; keeping the gate on the caller means every
explicit request (retry, load-older, a rekey's catch-up) stays exact.
- **§6's send-time deferral is closed in the same phase.** The plan framed it as a
wire-level gap to decide later, but it is the same lie in the other direction: a
member a rotation excluded could type, press enter, watch the message disappear
into a plane nobody reads, and be told nothing. `channel_secret` refusing is what
makes the notice actionable.
- **Spawned work is tracked, not detached.** `Community::tasks` and
`CommunityPanel::tasks` hold every fold, round bookkeeping step and publish, so
closing a panel or signing out cancels them instead of letting them finish
against a client nobody holds. Each push drops the tasks that already finished.
Phase 4 leaves the client honest about what it can see and what it can write.
What it does not do is make it see more: the rekey writer, and with it adopting a
rotation this client published itself, was still open there (§6, closed in
phase 6).
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
is what keeps a rekey from stranding history; phase 4 is what makes an empty or
unreadable room tell the truth.
### Phase 5 — typed time — **landed**
§10. `HeldKey`/`HeldRoot.retired_at`, `ChannelCursor`, `WrapPage`, `Plane`,
`Window` and the `Walk` bounds are `Timestamp`s; `channel_cuts` is `Epoch`;
`CURSOR_OVERLAP` is a `Duration`; and the cursor map's serde key was retired so no
stored millisecond cursor is read as seconds. No behaviour change, no relay
contact, no new dependency — the units the read path already compared by hand are
now the types it compares.
Gate, all green: `cargo test -p concord -p community` (51 + 32),
`cargo clippy -p concord -p community -p community_ui --all-targets`,
`cargo +nightly fmt -p concord -p community -p community_ui --check`,
`cargo check -p workspace --all-targets`.
### Phase 6 — the rekey writer — **landed**
§6's writer: `cord06::plan_rotation`, `rekey::{Rewrite, rotate}`, `carry_heads`,
and `Community::rotate`, which publishes a rotation and then adopts it through the
receiver phase 3 built. The receiver also keeps the signing root a refounding
hands it now, instead of dropping it.
Gate, all green: `cargo test -p concord -p community` (51 + 32),
`cargo clippy -p concord -p community -p community_ui --all-targets`,
`cargo +nightly fmt -p concord -p community -p community_ui --check`,
`cargo check -p workspace --all-targets`. No test was added for the writer itself:
the publish half needs a relay, and the same reason the reference's own rekey
paths are exercised by hand applies here — see `Tests` below.
## 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 landed in §6 (phase 3); honest empty states
remain open 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 cursor's unit — **landed in phase 5**: a merge only moves forward and never
earns `exhausted`; a document whose cursors were stored in the old millisecond
encoding reads as no cursors at all, while a typed one round-trips
(`concord/src/state.rs`).
- 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 rekey watch and adoption — **landed in phase 3** (`community/src/rekey.rs`
tests): a complete base rotation whose `prevcommit` extends the held root is
adopted with the prior root retired at the rotation's publish time; a rotation
off a key we do not hold is never adopted; a complete blob-less rotation from a
rotator who outranks us, published after we joined, reads as a removal; a
channel rotation replaces the key and keeps the prior. The pump's half
(`community/src/lib.rs`) is that a rekey watch's event wakes its community.
- The rekey writer — **landed in phase 6, structurally only.** No test covers it:
the half that could be tested without a relay (that `plan_rotation` mints two
unrelated keys, that `Rewrite::authorized` agrees with the receiver) would not
catch the failures that matter (a blob addressed to the wrong epoch, a chunk set
the receiver cannot collect, a refounding that carries no head), and the half
that would — publish, re-read, adopt — needs a real relay and a second account.
What stands in for it is that the writer cannot take a path the receiver does
not: same `permissions`, same `build_rekey_chunks`, and adoption goes through
`rekey::adopt` rather than beside it.
- The read path: the side-event budget folds an edit/delete/reaction older than
the row window onto its message.
- What cannot be read — **landed in phase 4**: a wrap sealed after the rotation
that retired the key reading it, and a wrap sealed to this plane but bound to
another channel, both read as unreadable rather than dropped
(`community/src/history.rs`); a fold counts a wrap addressed to a held channel
plane that will not open (`community/src/sync.rs`).
- The honest states — **landed in phase 4** structurally: `Snapshot.unreadable`
and `Progress.unreadable` are what the panel's notice and the `Unreadable`
event read, and the `Failed` event is what a failed round emits. The panel's
precedence (stranded → removed → missing key → unreachable → unreadable →
empty) itself needs a `TestAppContext`, which the repo still does not have.
- The scheduler — **landed in phase 4** structurally: `due()` is false inside
`MIN_ROUND_INTERVAL` after a round, `stale()` requires a recorded round older
than `STALE_AFTER`, and `tick` acts only on the active channel. Driving real
time needs the same harness.
- 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; the panel's notice precedence; `due()`/`stale()`
under a driven clock. (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, and one
run with a relay stopped so the notice and its retry are visible. 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, see the other account's message appear without a reload,
and see a room we cannot read say so instead of "No messages yet".
## 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.
The rekey writer is the one exception, and only its mechanism: `Community::rotate`
exists to be called, but nothing in the app calls it. Kicking a member, choosing
the audience a rotation keeps, and showing any of it stay out.
`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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