TypeScript Web Messaging SDK hook interception failing on carousel render and scroll sync

@genesys/web-messaging-client-initializes the message stream before the React component tree mounts, so I’ve been trying to override the onMessageRender hook with a custom TypeScript wrapper. Failed. The markdown parser throws a TypeError: Cannot read properties of undefined when the payload contains nested carousel JSON, and moving the carousel rendering to a separate React component doesn’t fix the media playback crashes. It’s failing on the thumbnail fallback too. Added a WebSocket listener for scroll:ack events to sync position, but the server returns a 400 Bad Request on the acknowledgment payload because the conversationId field gets stripped during the handshake.

Tried wrapping the hook in a useEffect and swapped the markdown library to marked. Still breaks on complex carousels. The WebSocket message format expects a flat JSON object but the serializes it as an array. How do I properly intercept the rendering pipeline without breaking the internal state machine. Need the exact TypeScript interface for the hook override.

Are you actually parsing the payload before the hook runs?

const safePayload = typeof raw === 'string' ? JSON.parse(raw) : raw;

You’ll break the scroll sync if you don’t set MESSAGING_CONFIG to bypass and bump RENDER_TIMEOUT to 2000, so just drop the custom wrapper.

const payload = JSON.stringify(raw);

Error

The carousel renderer demands a strict JSON string. You’ll hit a validation error without it. It’s choking on the object type.

Hi all,

Fun one today. It looks like everyone’s hitting the same spot - the carousel component is…particular about its input. The suggestion above about stringifying the payload is correct, but there’s a wrinkle to it.

Here’s what’s happening. The expects a string, yes, but it’s also doing its own internal parsing after you’ve already provided it. This double-parsing is where the TypeError originates. It’s trying to JSON.parse something that’s already an object, or in some cases, a string that it then expects to be an object.

To get around this, you need to ensure the payload is always a string before passing it to the hook, but then prevent the from re-parsing it. ’s advice to bypass the render timeout is good, but doesn’t address the root issue. The underlying problem is that the onMessageRender hook receives the already-parsed object, and attempts to re-serialize it.

Here’s a more complete approach. This assumes raw is the initial payload from the messaging stream.

const payload = typeof raw === 'string' ? raw : JSON.stringify(raw);

// Then, within your hook, ensure you're working with a string
const parsedPayload = JSON.parse(payload); // This is likely redundant, but keeps things consistent.

// Now, proceed with rendering, knowing payload is a string
// and parsedPayload holds the object representation

A couple of points. The RENDER_TIMEOUT bump to 2000 is a useful band-aid for initial loading, but don’t leave it there permanently. It hides performance issues. More importantly, the carousel component has a subtle dependency on the MESSAGING_CONFIG flag - the internal rendering logic expects bypass to be set to true when handling carousel payloads. It’s a quirk of the implementation.

I’ve seen cases where the component will render a broken carousel, or just plain crash, without that flag. You’ll have to modify the MESSAGING_CONFIG object before passing it to the . It’s not documented well, I know.

Finally, I’d suggest checking the console for any validation errors. The error message will be buried, but it’s usually a clue about what the carousel component is expecting.

web-messaging-client needs a pre-stringified payload. Drop the wrapper - it’s fighting the internal parser.

const payload = JSON.stringify(raw);

Bump RENDER_TIMEOUT to 2000, set MESSAGING_CONFIG to bypass. Carousel’s just picky.