EventBridge Rule missing 'source' for Genesys Cloud events?

Trying to wire up EventBridge to catch agent state changes. The docs are vague on the exact source value.

Here’s the rule I’m testing:

{
 "source": [
 "aws.genesis"
 ],
 "detail-type": [
 "Genesys Cloud Event"
 ]
}

No matches. I’ve also tried genesys.cloud and com.genesys.cloud. All return 0 matches in the CloudWatch logs.

Is there a specific source string for the CXone integration, or am I missing a step in the webhook config on the Genesys side?