release(v4.7.0): peer-presence events for instant BroadcastChannel revoke

Adds the bridge-connection-lifecycle signal that closes Prism's
~45s revoke window down to one server→client round-trip (~50ms).

Server (`@shade/inbox-server`):
- `inbox.peer_connected` / `inbox.peer_disconnected` events on the
  0↔1 boundary across WS + SSE bridges. Long-poll deliberately not
  tracked (every poll boundary would flap; push transports are also
  the only ones where instant revoke matters).
- `PresenceTracker` collapses two parallel bridges (e.g. WS + SSE
  during fallback handover) into one connect/disconnect pair.
- `GET /v1/bridge/presence` SSE endpoint: signed query with
  `kind: 'presence'`, `watched: string[]`; on open streams a
  per-address snapshot, then change frames filtered server-side.
  MAX_WATCHED_ADDRESSES = 64. Subscribing does not itself count as
  a peer-bridge connection.
- `createBridgeRoutes` now returns `{ app, websocket, presence }`.

Client (`@shade/transport-bridge`):
- `PresenceBridge.subscribe({ watch, onPresenceChange })` →
  `{ addPeer, removePeer, watching, unsubscribe }`. addPeer/removePeer
  mutate via reconnect with a fresh signed query.
- `signPresenceQuery` helper for non-PresenceBridge consumers.

Tests cover all four acceptance criteria from the Prism request:
server-event smoke, online→offline subscription, address scoping
(carol invisible to a [alice]-only sub), reconnect, plus an
addPeer/removePeer regression.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shade-inbox-server/src/bridge.ts

@@ -38,8 +38,15 @@ import {
 import { verifyPayload, validateAddress } from '@shade/server';
 import type { InboxStore } from './store.js';
 import type { InboxServerEvents } from './events.js';
+import { PresenceTracker, type TrackedBridgeKind } from './presence.js';
 
 export type BridgeKind = 'stream' | 'poll' | 'ws';
+/**
+ * Wire-protocol kind tag for `/v1/bridge/presence`. Distinct from
+ * `BridgeKind` because the canonical signed payload is shaped
+ * differently (`watched: string[]` instead of `since: number`).
+ */
+export type PresenceKind = 'presence';
 
 export interface BridgeRoutesOptions {
   store: InboxStore;
@@ -60,6 +67,13 @@ export interface BridgeRoutesOptions {
    * Default 1_000.
    */
   fallbackPollIntervalMs?: number;
+  /**
+   * Inject an existing presence tracker. Useful when multiple
+   * `createBridgeRoutes` calls need to share state (e.g. mounting the
+   * routes under several hostnames in a single process). When omitted,
+   * the bridge auto-creates an internal tracker bound to `events`.
+   */
+  presenceTracker?: PresenceTracker;
 }
 
 interface VerifiedBridgeRequest {
@@ -68,6 +82,13 @@ interface VerifiedBridgeRequest {
   since: number;
 }
 
+interface VerifiedPresenceRequest {
+  /** The watcher's address (signer of the request). */
+  address: string;
+  /** Addresses whose presence the watcher is asking to track. */
+  watched: string[];
+}
+
 /**
  * Build the bridge Hono router and a paired Bun-WebSocket handler.
  *
@@ -80,6 +101,8 @@ export function createBridgeRoutes(opts: BridgeRoutesOptions): {
   app: Hono;
   /** Pass to `Bun.serve({ websocket })`. Undefined if Bun adapter is missing. */
   websocket: unknown;
+  /** Live presence tracker. Tests + observers can read it; routes update it. */
+  presence: PresenceTracker;
 } {
   const app = new Hono();
   const pageLimit = opts.pageLimit ?? 50;
@@ -87,6 +110,7 @@ export function createBridgeRoutes(opts: BridgeRoutesOptions): {
   const longPollDefault = opts.longPollTimeoutMs ?? 25_000;
   const longPollMax = opts.longPollMaxTimeoutMs ?? 55_000;
   const fallbackPollIntervalMs = opts.fallbackPollIntervalMs ?? 1_000;
+  const presence = opts.presenceTracker ?? new PresenceTracker(opts.events ?? null);
 
   app.onError((err, c) => {
     if (err instanceof ShadeError) {
@@ -102,6 +126,14 @@ export function createBridgeRoutes(opts: BridgeRoutesOptions): {
     const verified = await verifyBridgeAuth(c, opts, 'stream');
     return streamSSE(c, async (stream) => {
       const address = verified.address;
+      const connId = presence.newConnectionId();
+      presence.markConnected(address, 'sse', connId);
+      let presenceClosed = false;
+      const closePresence = (reason: 'closed' | 'error'): void => {
+        if (presenceClosed) return;
+        presenceClosed = true;
+        presence.markDisconnected(address, 'sse', connId, reason);
+      };
       let cursor = verified.since;
       const writer = makeBlobWriter(opts.store, pageLimit);
 
@@ -163,6 +195,68 @@ export function createBridgeRoutes(opts: BridgeRoutesOptions): {
       clearInterval(fallbackTimer);
       clearInterval(heartbeat);
       await pendingFlushPromise.catch(() => {});
+      closePresence('closed');
+    });
+  });
+
+  // ─── Presence (V4.7) ──────────────────────────────────────────
+  // SSE feed of `peer_connected` / `peer_disconnected` events filtered
+  // by a watcher-supplied address list. Subscribing does NOT count as
+  // a peer-bridge connection (it doesn't call `markConnected`) so
+  // monitoring presence doesn't make you appear online to others.
+  app.get('/v1/bridge/presence', async (c) => {
+    const verified = await verifyPresenceAuth(c, opts);
+    return streamSSE(c, async (stream) => {
+      const watched = new Set(verified.watched);
+
+      // Initial snapshot — one frame per watched address with current
+      // status. Lets subscribers render UI immediately rather than
+      // waiting for the next state change.
+      const now = Date.now();
+      for (const addr of verified.watched) {
+        await stream.writeSSE({
+          event: 'presence',
+          data: JSON.stringify({
+            address: addr,
+            status: presence.isOnline(addr) ? 'online' : 'offline',
+            at: now,
+          }),
+        });
+      }
+
+      let unsubscribe: (() => void) | null = null;
+      if (opts.events) {
+        unsubscribe = opts.events.on((e) => {
+          if (e.name !== 'inbox.peer_connected' && e.name !== 'inbox.peer_disconnected') return;
+          const data = e.data as { address: string; bridgeKind: TrackedBridgeKind };
+          if (!watched.has(data.address)) return;
+          const status = e.name === 'inbox.peer_connected' ? 'online' : 'offline';
+          // Fire-and-forget: drop the frame if the stream has gone away.
+          void stream
+            .writeSSE({
+              event: 'presence',
+              data: JSON.stringify({
+                address: data.address,
+                status,
+                at: e.timestamp,
+                via: data.bridgeKind,
+              }),
+            })
+            .catch(() => {});
+        });
+      }
+      const heartbeat = setInterval(() => {
+        stream.write(`: ping ${Date.now()}\n\n`).catch(() => {});
+      }, heartbeatIntervalMs);
+
+      await new Promise<void>((resolve) => {
+        const sig = c.req.raw.signal;
+        if (sig.aborted) return resolve();
+        sig.addEventListener('abort', () => resolve(), { once: true });
+      });
+
+      unsubscribe?.();
+      clearInterval(heartbeat);
     });
   });
 
@@ -230,6 +324,7 @@ export function createBridgeRoutes(opts: BridgeRoutesOptions): {
       }
 
       const address = verified.address;
+      const connId = presence.newConnectionId();
       let cursor = verified.since;
       const writer = makeBlobWriter(opts.store, pageLimit);
       let unsubscribe: (() => void) | null = null;
@@ -237,12 +332,19 @@ export function createBridgeRoutes(opts: BridgeRoutesOptions): {
       let pendingFlushPromise: Promise<void> = Promise.resolve();
       let signalled = false;
       let connected = true;
+      let presenceClosed = false;
+      const closePresence = (reason: 'closed' | 'error'): void => {
+        if (presenceClosed) return;
+        presenceClosed = true;
+        presence.markDisconnected(address, 'ws', connId, reason);
+      };
 
       return {
         onOpen(_evt: unknown, ws: {
           send: (data: string) => void;
           close: (code?: number, reason?: string) => void;
         }) {
+          presence.markConnected(address, 'ws', connId);
           const triggerFlush = (): void => {
             signalled = true;
             pendingFlushPromise = pendingFlushPromise.then(async () => {
@@ -269,12 +371,19 @@ export function createBridgeRoutes(opts: BridgeRoutesOptions): {
           connected = false;
           unsubscribe?.();
           if (fallbackTimer) clearInterval(fallbackTimer);
+          closePresence('closed');
+        },
+        onError() {
+          connected = false;
+          unsubscribe?.();
+          if (fallbackTimer) clearInterval(fallbackTimer);
+          closePresence('error');
         },
       };
     }),
   );
 
-  return { app, websocket };
+  return { app, websocket, presence };
 }
 
 // ─── helpers ──────────────────────────────────────────────────
@@ -321,6 +430,68 @@ async function verifyBridgeAuth(
   return { address, kind: kind as BridgeKind, since };
 }
 
+const MAX_WATCHED_ADDRESSES = 64;
+
+/**
+ * Verify a `/v1/bridge/presence` request.
+ *
+ * Signed canonical payload: `{address, kind: 'presence', watched: string[],
+ * signedAt}`. The watcher's address must be a registered inbox; the
+ * signature is verified against the registered owner key for that
+ * address. The `watched` list bounds what the subscription will
+ * receive — server-side filtering is enforced inside the handler.
+ */
+async function verifyPresenceAuth(
+  c: Context,
+  opts: BridgeRoutesOptions,
+): Promise<VerifiedPresenceRequest> {
+  const url = new URL(c.req.url);
+  const qs = url.searchParams;
+  const address = validateAddress(qs.get('address'));
+  const kind = qs.get('kind');
+  if (kind !== 'presence') {
+    throw new ValidationError(`bridge kind mismatch: expected presence`, 'kind');
+  }
+  const watchedRaw = qs.get('watched');
+  if (watchedRaw === null) throw new ValidationError('missing watched', 'watched');
+  // Empty subscription is allowed (subscribe to nothing — useful for a
+  // client that intends to call addPeer right after open). A null/
+  // missing param is still rejected so the canonicalization is
+  // unambiguous.
+  const watched =
+    watchedRaw === ''
+      ? []
+      : watchedRaw.split(',').map((a) => validateAddress(a));
+  if (watched.length > MAX_WATCHED_ADDRESSES) {
+    throw new ValidationError(
+      `watched list too large: ${watched.length} > ${MAX_WATCHED_ADDRESSES}`,
+      'watched',
+    );
+  }
+  const signedAtStr = qs.get('signedAt');
+  const signature = qs.get('signature');
+  if (signedAtStr === null) throw new ValidationError('missing signedAt', 'signedAt');
+  if (!signature) throw new ValidationError('missing signature', 'signature');
+  const signedAt = Number(signedAtStr);
+  if (!Number.isFinite(signedAt)) {
+    throw new ValidationError('signedAt must be a number', 'signedAt');
+  }
+
+  const owner = await opts.store.getAddressOwner(address);
+  if (!owner) {
+    throw new UnauthorizedError(`address ${address} is not registered`);
+  }
+
+  await verifyPayload(opts.crypto, owner, {
+    address,
+    kind,
+    watched,
+    signedAt,
+    signature,
+  });
+  return { address, watched };
+}
+
 interface BlobRow {
   msgId: string;
   ciphertext: Uint8Array;

packages/shade-inbox-server/src/events.ts

@@ -21,6 +21,19 @@ export interface InboxServerEventMap {
   'inbox.expired_purged': { count: number };
   'inbox.rate_limited': { route: string; key: string };
   'inbox.quota_rejected': { address: string; reason: 'address-quota' | 'sender-quota' | 'body-too-large' };
+  // V4.7 — bridge presence transitions. Emitted on the 0↔1 boundary
+  // across tracked transports for a given address. Long-poll is
+  // intentionally NOT tracked: an LP client toggles in/out of a request
+  // every few seconds, and the resulting flapping would dominate the
+  // event stream. Push transports (WS, SSE) are also the only ones
+  // where the ~50ms revoke window for `BroadcastChannel.removeMember`
+  // matters — long-poll users are already on a slow path.
+  'inbox.peer_connected': { address: string; bridgeKind: 'ws' | 'sse' };
+  'inbox.peer_disconnected': {
+    address: string;
+    bridgeKind: 'ws' | 'sse';
+    reason: 'closed' | 'error';
+  };
 }
 
 export type InboxServerEventName = keyof InboxServerEventMap;

packages/shade-inbox-server/src/index.ts

@@ -32,6 +32,8 @@ export {
 export type { InboxQuotaConfig } from './quota.js';
 export { createBridgeRoutes } from './bridge.js';
 export type { BridgeRoutesOptions, BridgeKind } from './bridge.js';
+export { PresenceTracker } from './presence.js';
+export type { TrackedBridgeKind } from './presence.js';
 
 /**
  * Create a standalone Shade Inbox Server.

packages/shade-inbox-server/src/presence.ts

@@ -0,0 +1,75 @@
+/**
+ * V4.7 — bridge-connection presence tracking.
+ *
+ * The bridge handlers (`/v1/bridge/stream` and `/v1/bridge/ws`) call
+ * `markConnected` on open and `markDisconnected` on close. The tracker
+ * keeps a per-address set of connection ids; the `inbox.peer_connected`
+ * / `inbox.peer_disconnected` events fire only on the 0↔1 boundary so
+ * that two simultaneous bridges (e.g. SSE + WS during a transport-
+ * fallback handover) collapse into a single connected/disconnected
+ * pair from the consumer's point of view.
+ *
+ * Long-poll (`/v1/bridge/poll`) is intentionally NOT tracked — see the
+ * note on `InboxServerEventMap` in `events.ts`.
+ */
+
+import type { InboxServerEvents } from './events.js';
+
+export type TrackedBridgeKind = 'ws' | 'sse';
+
+export class PresenceTracker {
+  private readonly connections = new Map<string, Set<string>>();
+  private nextConnId = 1;
+
+  constructor(private readonly events: InboxServerEvents | null) {}
+
+  /** Allocate a fresh connection id for `markConnected` / `markDisconnected`. */
+  newConnectionId(): string {
+    return `c${this.nextConnId++}`;
+  }
+
+  /**
+   * Snapshot: is `address` currently connected over any tracked transport?
+   * Used by `/v1/bridge/presence` to push the initial state to a new
+   * subscriber.
+   */
+  isOnline(address: string): boolean {
+    const set = this.connections.get(address);
+    return set !== undefined && set.size > 0;
+  }
+
+  markConnected(address: string, bridgeKind: TrackedBridgeKind, connectionId: string): void {
+    let set = this.connections.get(address);
+    const wasOnline = set !== undefined && set.size > 0;
+    if (!set) {
+      set = new Set();
+      this.connections.set(address, set);
+    }
+    set.add(connectionId);
+    if (!wasOnline) {
+      this.events?.emit('inbox.peer_connected', { address, bridgeKind });
+    }
+  }
+
+  markDisconnected(
+    address: string,
+    bridgeKind: TrackedBridgeKind,
+    connectionId: string,
+    reason: 'closed' | 'error',
+  ): void {
+    const set = this.connections.get(address);
+    if (!set) return;
+    if (!set.delete(connectionId)) return;
+    if (set.size === 0) {
+      this.connections.delete(address);
+      this.events?.emit('inbox.peer_disconnected', { address, bridgeKind, reason });
+    }
+  }
+
+  /** Inspect the underlying map. Test/observability use only. */
+  snapshot(): Map<string, ReadonlySet<string>> {
+    return new Map(
+      Array.from(this.connections.entries(), ([k, v]) => [k, v as ReadonlySet<string>]),
+    );
+  }
+}