We are trying to send a card payload using the /api/v2/conversations/messaging endpoint. The text message works, but the structured object returns a 400 Bad Request. Here is the JSON we are sending:
{
"to": [{"id": "user_123"}],
"type": "card",
"payload": {"title": "Test"}
}
The error says the payload is invalid. We have tried different structures but nothing sticks. Can you see what is wrong with this format?