feat(plugin): fabric-guild-list + fabric-channel-set-purpose tools + purpose on existing tools

Adds two agent-facing tools that close the discoverability loop:

  - fabric-guild-list — enumerates guilds the agent belongs to with
    name + purpose + status (no api calls beyond the existing agentLogin
    response). Optional nameFilter/purposeFilter for narrowing.
  - fabric-channel-set-purpose — PATCH /api/channels/:id { purpose }
    so agents can backfill or update an existing channel's purpose.

Extends existing tools:
  - fabric-channel-list now returns purpose on each row.
  - create-{chat,work,report,discussion}-channel accept optional purpose.

FabricClient + FabricSession type changes carry the new field through.
Manifest contracts.tools updated (jiti loader needs both manifest entry
and onStartup activation to register).

Lets workflows that previously needed hardcoded channel ids instead say
'find a guild whose purpose mentions debate, then a channel of x_type
announce whose purpose covers public debate broadcasts.'

dist/fabric/index.js

@@ -12,10 +12,16 @@ import { registerFabricTools } from './src/tools.js';
 import { FabricClient } from './src/fabric-client.js';
 import { IdentityRegistry } from './src/identity.js';
 import { syncFabricCommands } from './src/command-sync.js';
+import { PresenceSync } from './src/presence-sync.js';
 import path from 'node:path';
 import os from 'node:os';
 let runtimeRef = null;
 let inbound = null;
+let presence = null;
+// Periodic re-harvest of presence accounts so newly-connected agents
+// (registered through tool-based identity flow AFTER initial start)
+// get picked up. Cleared on gateway_stop.
+let presenceRefreshTimer = null;
 export { fabricChannelPlugin } from './src/channel.js';
 export default defineChannelPluginEntry({
     id: 'fabric',
@@ -57,7 +63,25 @@ export default defineChannelPluginEntry({
                 return;
             }
             inbound = new FabricInbound(runtimeRef, api.config, client, identity, api.logger, accounts);
-            void inbound.start();
+            // start() resolves once all accounts have attempted login; per-
+            // agent failures are logged but don't reject. Once it resolves we
+            // can harvest the presence accounts (those that DID log in have
+            // their fabricUserId + first guild endpoint populated).
+            void inbound.start().then(() => {
+                if (!inbound)
+                    return;
+                presence = new PresenceSync(api.logger);
+                presence.setAccounts(inbound.getPresenceAccounts());
+                presence.start();
+                api.logger.info(`fabric: presence-sync started for ${inbound.getPresenceAccounts().length} account(s)`);
+                // Re-harvest every 5 min: catches agents added via tool-based
+                // identity provisioning after gateway_start (recruitment flow).
+                // setAccounts is idempotent — duplicates collapse on agentId.
+                presenceRefreshTimer = setInterval(() => {
+                    if (inbound && presence)
+                        presence.setAccounts(inbound.getPresenceAccounts());
+                }, 5 * 60_000);
+            });
             api.logger.info(`fabric: inbound started for ${accounts.length} account(s)`);
             void syncFabricCommands(client, cfg, accounts, api.logger);
         });
@@ -67,6 +91,12 @@ export default defineChannelPluginEntry({
         // BEFORE deliver()). gateway_stop only flushes any leftover buffer.
         api.on('gateway_stop', () => {
             void flushAllFabric();
+            if (presenceRefreshTimer) {
+                clearInterval(presenceRefreshTimer);
+                presenceRefreshTimer = null;
+            }
+            presence?.stop();
+            presence = null;
             inbound?.stop();
             inbound = null;
         });