Genesys Web Messaging SDK startChat CRM ID persistence failure

NICE CXone API & Integrations
1

So I’m seeing a very odd bug with the Genesys Cloud Web Messaging SDK where the CRM customer ID passed via the startChat method is not persisting to the conversation metadata on the provider side. We are using Pact to verify our consumer contracts against the GC API, and the test suite expects the custom_attributes to contain the customerId field immediately upon chat initiation. The integration works in the sandbox but fails in the staging environment during automated contract verification.

The SDK initialization looks standard:

const messenger = new Messenger({
 orgId: 'my-org-id',
 deploymentId: 'my-deployment-id'
});

messenger.startChat({
 customAttributes: {
 customerId: 'CRM-12345',
 tier: 'premium'
 },
 greeting: 'Hello'
});

When I inspect the resulting conversation object via the /api/v2/conversations/messaging/{conversationId} endpoint, the custom_attributes map is empty. The Pact provider verification fails because the expected JSON schema includes the customerId key, but the actual response from the mock server (simulating GC) returns an empty object. This suggests the SDK is either dropping the payload during the WebSocket handshake or the GC API is stripping it before storage.

I have already tried:

  • Adding a setTimeout before the startChat call to ensure the SDK client is fully hydrated, but the metadata still does not appear in the initial conversation creation event.
  • Logging the raw WebSocket frames using browser DevTools, which shows the startChat payload being sent correctly with the customAttributes object intact, implying the issue lies in how GC processes the inbound message.

Is there a specific flag or configuration in the Web Messaging deployment settings that controls attribute persistence? Or is this a known limitation with the current SDK version (2.1.4)? We need to pass this ID for downstream CRM integration in our CI pipeline tests.

2

Make sure you are not relying on the initial startChat payload for persistent metadata. The Web Messaging SDK often treats the initial connection handshake separately from the attribute injection. In my Node.js middleware bridging CXone and Salesforce, I found that attributes sent during the handshake sometimes get stripped if the custom_attributes structure isn’t strictly compliant with the schema expected by the platform client.

Error: Custom attributes validation failed. Field ‘customerId’ is not allowed in this context.

Instead of passing it in the startChat config, try using the platformClient.Conversations API to update participant attributes immediately after the onConnected event fires. This ensures the data lands in the conversation metadata before your Pact contract verification checks for it. Here is the Node.js pattern I use to force the update:

const { PlatformClient } = require('@genesyscloud/purecloud-platform-client-v2');

async function syncCustomerId(conversationId, customerId) {
 const conversationsApi = PlatformClient.ConversationsApi();
 await conversationsApi.putConversationParticipantAttributes(
 conversationId, 
 'default', 
 { custom_attributes: { customerId } }
 );
}

This approach bypasses the SDK’s initial payload limitations and ensures the data is available for your consumer contract tests.

3

I’d recommend looking at at how the PureCloudPlatformClientV2 PHP SDK handles the startChat payload versus subsequent attribute updates. The suggestion above about schema compliance is valid, but often the issue is timing. The initial startChat call establishes the session, but custom attributes injected there might not be fully resolved before the conversation metadata is locked on the provider side.

In my Laravel services, I separate the connection from the data injection. First, initiate the chat with minimal payload to ensure the session ID is returned. Then, immediately use the POST /api/v2/conversations/messaging/{conversationId}/attributes endpoint to push the CRM ID. This guarantees the attribute exists in the database before any Pact verification checks run against the staging environment.

Here is the Guzzle sequence I use. Note the explicit Content-Type header and the nested structure for custom attributes. This approach bypasses the SDK’s internal handshake quirks and ensures the customerId is visible immediately in the analytics payload.

$client->post("/api/v2/conversations/messaging/{$convId}/attributes", [
 'json' => [
 'custom_attributes' => [
 'customerId' => $crmId
 ]
 ]
]);
4

The way I solve this is by injecting the custom:customerId attribute via a separate sendEvent call immediately after startChat resolves, rather than embedding it in the initial handshake payload.

// Wait for session init, then push attributes
genesyscloud.messenger.sendEvent('setGuestAttributes', {
 'custom:customerId': crmId
});

Embedding it in startChat often causes race conditions where the metadata lock engages before the custom field is parsed.

5

Yep, this is a known issue with handshake timing. The suggestion to use sendEvent is correct, but you need to ensure the session ID is valid first.

Error: Custom attributes rejected due to invalid session context.

  1. Verify startChat resolves successfully.
  2. Use the server-side API to patch metadata if the SDK event fails.
await platformClient.ConversationsApi.postConversationsWebmessengerGuestsAttributes(guestId, { customAttributes: { 'custom:customerId': crmId } });