Prevent addCOntextListener race conditions by making ChannelSupport a Connectable

Author: kriswest

CHANGELOG.md

@@ -68,6 +68,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * Resolved vulnerable dependencies (esbuild, serialize-javascript, elliptic) and consolidated shared devDependencies to simplify future maintenance. ([#1841](https://github.com/finos/FDC3/pull/1841))
 * Fixed the lack of handling of WCP6Disconnect messages in MessagePort example in the FDC3 Web reference implementation. ([#1854](https://github.com/finos/FDC3/pull/1854))
 * Fixed handling of DesktopAgents that start apps joined to a user channel by the agent-proxy by retrieving the current user channel on start-up. ([#1858](https://github.com/finos/FDC3/pull/1858))
+* Fixed a race condition in `DefaultChannelSupport` initialization where the current user channel was retrieved asynchronously without being awaited, which could cause apps started on a user channel by the Desktop Agent to miss their initial channel assignment. ([#1858](https://github.com/finos/FDC3/pull/1858))
 
 ## [FDC3 Standard 2.2](https://github.com/finos/FDC3/compare/v2.1..v2.2) - 2025-03-12
 

packages/fdc3-agent-proxy/src/channels/ChannelSupport.ts

@@ -1,6 +1,14 @@
-import { Channel, ContextHandler, EventHandler, FDC3EventTypes, Listener, PrivateChannel } from '@finos/fdc3-standard';
+import {
+  Channel,
+  Connectable,
+  ContextHandler,
+  EventHandler,
+  FDC3EventTypes,
+  Listener,
+  PrivateChannel,
+} from '@finos/fdc3-standard';
 
-export interface ChannelSupport {
+export interface ChannelSupport extends Connectable {
   getUserChannel(): Promise<Channel | null>;
   getUserChannels(): Promise<Channel[]>;
   getOrCreate(id: string): Promise<Channel>;

packages/fdc3-agent-proxy/src/channels/DefaultChannelSupport.ts

@@ -1,5 +1,6 @@
 import {
   Channel,
+  Connectable,
   ContextHandler,
   Listener,
   PrivateChannel,
@@ -35,7 +36,7 @@ import {
 import { throwIfUndefined } from '../util/throwIfUndefined.js';
 import { Logger } from '../util/Logger.js';
 
-export class DefaultChannelSupport implements ChannelSupport {
+export class DefaultChannelSupport implements ChannelSupport, Connectable {
   readonly messaging: Messaging;
   readonly channelSelector: ChannelSelector;
   readonly messageExchangeTimeout: number;
@@ -55,14 +56,14 @@ export class DefaultChannelSupport implements ChannelSupport {
         this.joinUserChannel(channelId);
       }
     });
+  }
 
+  async connect(): Promise<void> {
     //retrieve the current user channel in case the Desktop Agent started us on a channel
-    this.getUserChannel().then((channel: Channel | null) => {
-      this.currentChannel = channel;
-    });
+    this.currentChannel = await this.getUserChannel();
 
     //register for channelChangedEvents to track any DesktopAgent managed user channel changes
-    this.addEventListener(async (e: ApiEvent) => {
+    await this.addEventListener(async (e: ApiEvent) => {
       const cce = e as FDC3ChannelChangedEvent;
       const newChannelId = cce.details.currentChannelId;
       Logger.debug('Desktop Agent reports channel changed: ', newChannelId);
@@ -91,6 +92,10 @@ export class DefaultChannelSupport implements ChannelSupport {
     }, 'userChannelChanged');
   }
 
+  async disconnect(): Promise<void> {
+    // no-op
+  }
+
   async addEventListener(handler: EventHandler, type: FDC3EventTypes | null): Promise<Listener> {
     const listener = new DesktopAgentEventListener(this.messaging, this.messageExchangeTimeout, type, handler);
     await listener.register();

packages/fdc3-agent-proxy/test/features/user-channels-set-by-agent.feature

@@ -13,9 +13,6 @@ Feature: User Channels Support where the Desktop Agent puts the app on a channel
     Then "{result}" is an object with the following contents
       | id  | type | displayMetadata.color |
       | one | user | red                   |
-    And messaging will have posts
-      | meta.source.appId | meta.source.instanceId | matches_type             |
-      | cucumber-app      | cucumber-instance      | getCurrentChannelRequest |
 
   Scenario: Adding a Typed Listener on a given User Channel
     Given "resultHandler" pipes context to "contexts"

packages/fdc3-agent-proxy/test/step-definitions/generic.steps.ts

@@ -31,7 +31,7 @@ function createDesktopAgent(world: CustomWorld, field: string, initialChannelId?
   const is = new DefaultIntentSupport(world.messaging, new SimpleIntentResolver(world), 1500, 3000);
   const as = new DefaultAppSupport(world.messaging, 1500, 3000);
 
-  const da = new DesktopAgentProxy(hs, cs, is, as, [hs], logLevel);
+  const da = new DesktopAgentProxy(hs, cs, is, as, [hs, cs], logLevel);
   return da;
 }
 

packages/fdc3-get-agent/src/messaging/message-port.ts

@@ -54,7 +54,7 @@ export async function createDesktopAgentAPI(
   const cs = new DefaultChannelSupport(messaging, channelSelector, cd.messageExchangeTimeout);
   const is = new DefaultIntentSupport(messaging, intentResolver, cd.messageExchangeTimeout, cd.appLaunchTimeout);
   const as = new DefaultAppSupport(messaging, cd.messageExchangeTimeout, cd.appLaunchTimeout);
-  const da = new DesktopAgentProxy(hs, cs, is, as, [hs, intentResolver, channelSelector], logLevel);
+  const da = new DesktopAgentProxy(hs, cs, is, as, [hs, cs, intentResolver, channelSelector], logLevel);
 
   Logger.debug('message-port: Connecting components ...');