Building a custom UI to bypass the standard Messenger widget. Using the Guest API to send messages directly via POST /api/v2/conversations/webmessaging/messages. I’m passing the conversationId from the session creation response. Getting a 403 Forbidden error. The Authorization: Bearer token is fresh. Here’s the payload:
{
"text": "Hello world"
}
Checked the docs, but nothing mentions permission scopes for raw guest message posting. Is there a specific header I’m missing?