fix: dynamically sync inbound channel subscriptions

The fabric inbound previously called `joinAll()` once on socket.io
`connect` — it fetched the agent's channel list via
`GET /api/channels?guildId=...` and emitted `join_channel` for each.
Any channel the agent joined *after* connect (e.g. a fresh DM created
by another user that includes this agent) was unreachable until the
gateway restarted: the socket was never subscribed to that room, so
backend `message.created` push events never arrived.

Backend doesn't emit a user-scoped `channel.joined` event we could
piggy-back on (only `message.created`), so the fix is to poll. Every
60s the agent's channel list is re-fetched and diffed against a local
`joined` set:
- new channel ids → `socket.emit('join_channel', {channelId})` + add
- ids in `joined` but absent from the fresh list → `leave_channel`
  emit + remove (best-effort; cleans subs if the agent is removed from
  a channel)

Re-uses `freshGuildToken()` so the resync fetch survives token
expiry (15-min TTL). Initial `connect` resets the local `joined`
set since the server forgets prior room subscriptions on reconnect.

Timers are tracked in `channelSyncTimers` and cleared in `stop()`
alongside socket disconnect.

Verified against prod server.t2 scenario: hzhang creates DM channel
including agent 'manager' → without this fix, manager only sees the
message after a gateway restart; with this fix, manager receives the
message within at most 60s (next resync tick).

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

dist/fabric/src/inbound.js

@@ -14,6 +14,14 @@ export class FabricInbound {
     accounts;
     sockets = [];
     seen = new Set();
+    // Timers that periodically re-sync channel membership per (agent, guild).
+    // Without this, the agent's socket.io subscriptions are a snapshot taken
+    // at connect time — any channel the agent joins later (e.g. a fresh DM
+    // created by another user) is unreachable until the gateway restarts.
+    channelSyncTimers = [];
+    // Resync cadence. Backend doesn't push a `channel.joined` event, so we
+    // poll. 60s keeps the lag bounded without hammering the backend.
+    static CHANNEL_SYNC_INTERVAL_MS = 60_000;
     // Guild access tokens are short-lived (~15 min). The socket survives via
     // socket.io reconnect, but the token captured at connect time goes stale,
     // so HTTP calls (attachment download, posting the reply) start 401ing.
@@ -75,6 +83,9 @@ export class FabricInbound {
         }
     }
     stop() {
+        for (const t of this.channelSyncTimers)
+            clearInterval(t);
+        this.channelSyncTimers = [];
         for (const s of this.sockets)
             s.disconnect();
         this.sockets = [];
@@ -90,19 +101,61 @@ export class FabricInbound {
                 auth: { token: tok },
                 autoConnect: false,
             });
-            const joinAll = async () => {
+            // Tracked socket.io rooms for this (agent, guild). The initial fetch
+            // on `connect` seeds it; the periodic resync diffs against it so we
+            // only emit `join_channel` for genuinely new channels (and
+            // `leave_channel` for ones the agent is no longer in).
+            const joined = new Set();
+            const syncChannels = async (kind) => {
+                let freshTok;
                 try {
-                    const res = await fetch(`${g.endpoint}/api/channels?guildId=${encodeURIComponent(g.nodeId)}`, { headers: { authorization: `Bearer ${tok}` } });
+                    freshTok = await this.freshGuildToken(agentId, g.nodeId, session);
-                    const channels = res.ok ? (await res.json()) : [];
-                    for (const c of channels)
-                        socket.emit('join_channel', { channelId: c.id });
-                    this.log.info(`fabric: agent ${agentId} joined ${channels.length} channel(s) on ${g.nodeId}`);
                 }
                 catch {
-                    /* best effort */
+                    freshTok = tok;
+                }
+                const authTok = freshTok ?? tok;
+                try {
+                    const res = await fetch(`${g.endpoint}/api/channels?guildId=${encodeURIComponent(g.nodeId)}`, { headers: { authorization: `Bearer ${authTok}` } });
+                    if (!res.ok)
+                        return;
+                    const channels = (await res.json());
+                    const current = new Set(channels.map((c) => c.id));
+                    let added = 0;
+                    let removed = 0;
+                    for (const id of current) {
+                        if (!joined.has(id)) {
+                            socket.emit('join_channel', { channelId: id });
+                            joined.add(id);
+                            added++;
+                        }
+                    }
+                    for (const id of [...joined]) {
+                        if (!current.has(id)) {
+                            socket.emit('leave_channel', { channelId: id });
+                            joined.delete(id);
+                            removed++;
+                        }
+                    }
+                    if (kind === 'initial') {
+                        this.log.info(`fabric: agent ${agentId} joined ${current.size} channel(s) on ${g.nodeId}`);
+                    }
+                    else if (added > 0 || removed > 0) {
+                        this.log.info(`fabric: agent ${agentId} channel resync on ${g.nodeId}: +${added} -${removed} (now ${joined.size})`);
+                    }
+                }
+                catch {
+                    /* best effort — next tick will retry */
                 }
             };
-            socket.on('connect', () => void joinAll());
+            socket.on('connect', () => {
+                // On every (re)connect the server forgets prior subscriptions, so
+                // reset our local view and seed from a fresh fetch.
+                joined.clear();
+                void syncChannels('initial');
+            });
+            const syncTimer = setInterval(() => void syncChannels('resync'), FabricInbound.CHANNEL_SYNC_INTERVAL_MS);
+            this.channelSyncTimers.push(syncTimer);
             socket.on('message.created', (m) => {
                 const channelId = m.channelId ?? '';
                 if (!channelId)

src/inbound.ts

@@ -52,6 +52,14 @@ type FabricMessage = {
 export class FabricInbound {
   private sockets: Socket[] = [];
   private seen = new Set<string>();
+  // Timers that periodically re-sync channel membership per (agent, guild).
+  // Without this, the agent's socket.io subscriptions are a snapshot taken
+  // at connect time — any channel the agent joins later (e.g. a fresh DM
+  // created by another user) is unreachable until the gateway restarts.
+  private channelSyncTimers: NodeJS.Timeout[] = [];
+  // Resync cadence. Backend doesn't push a `channel.joined` event, so we
+  // poll. 60s keeps the lag bounded without hammering the backend.
+  private static readonly CHANNEL_SYNC_INTERVAL_MS = 60_000;
   // Guild access tokens are short-lived (~15 min). The socket survives via
   // socket.io reconnect, but the token captured at connect time goes stale,
   // so HTTP calls (attachment download, posting the reply) start 401ing.
@@ -119,6 +127,8 @@ export class FabricInbound {
   }
 
   stop(): void {
+    for (const t of this.channelSyncTimers) clearInterval(t);
+    this.channelSyncTimers = [];
     for (const s of this.sockets) s.disconnect();
     this.sockets = [];
   }
@@ -133,20 +143,67 @@ export class FabricInbound {
         auth: { token: tok },
         autoConnect: false,
       });
-      const joinAll = async () => {
+      // Tracked socket.io rooms for this (agent, guild). The initial fetch
+      // on `connect` seeds it; the periodic resync diffs against it so we
+      // only emit `join_channel` for genuinely new channels (and
+      // `leave_channel` for ones the agent is no longer in).
+      const joined = new Set<string>();
+      const syncChannels = async (kind: 'initial' | 'resync') => {
+        let freshTok: string | undefined;
+        try {
+          freshTok = await this.freshGuildToken(agentId, g.nodeId, session);
+        } catch {
+          freshTok = tok;
+        }
+        const authTok = freshTok ?? tok;
         try {
           const res = await fetch(
             `${g.endpoint}/api/channels?guildId=${encodeURIComponent(g.nodeId)}`,
-            { headers: { authorization: `Bearer ${tok}` } },
+            { headers: { authorization: `Bearer ${authTok}` } },
           );
-          const channels = res.ok ? ((await res.json()) as Array<{ id: string }>) : [];
+          if (!res.ok) return;
-          for (const c of channels) socket.emit('join_channel', { channelId: c.id });
+          const channels = (await res.json()) as Array<{ id: string }>;
-          this.log.info(`fabric: agent ${agentId} joined ${channels.length} channel(s) on ${g.nodeId}`);
+          const current = new Set(channels.map((c) => c.id));
+          let added = 0;
+          let removed = 0;
+          for (const id of current) {
+            if (!joined.has(id)) {
+              socket.emit('join_channel', { channelId: id });
+              joined.add(id);
+              added++;
+            }
+          }
+          for (const id of [...joined]) {
+            if (!current.has(id)) {
+              socket.emit('leave_channel', { channelId: id });
+              joined.delete(id);
+              removed++;
+            }
+          }
+          if (kind === 'initial') {
+            this.log.info(
+              `fabric: agent ${agentId} joined ${current.size} channel(s) on ${g.nodeId}`,
+            );
+          } else if (added > 0 || removed > 0) {
+            this.log.info(
+              `fabric: agent ${agentId} channel resync on ${g.nodeId}: +${added} -${removed} (now ${joined.size})`,
+            );
+          }
         } catch {
-          /* best effort */
+          /* best effort — next tick will retry */
         }
       };
-      socket.on('connect', () => void joinAll());
+      socket.on('connect', () => {
+        // On every (re)connect the server forgets prior subscriptions, so
+        // reset our local view and seed from a fresh fetch.
+        joined.clear();
+        void syncChannels('initial');
+      });
+      const syncTimer = setInterval(
+        () => void syncChannels('resync'),
+        FabricInbound.CHANNEL_SYNC_INTERVAL_MS,
+      );
+      this.channelSyncTimers.push(syncTimer);
       socket.on('message.created', (m: FabricMessage) => {
         const channelId = m.channelId ?? '';
         if (!channelId) return;