Guest API /api/v2/webmessaging/guests/messages returns 400 on first send

Trying to bypass the standard widget to build a custom UI. I’m trying to send the initial message. The auth header is valid. The body looks right.

POST /api/v2/conversations/messages/{conversationId}/communications/{communicationId}/messages
{
“conversationId”: “conv-123”,
“text”: “hello”
}

Getting 400 Bad Request. Message says ‘Invalid guest state’. I checked the guest endpoint and it’s active. Tried waiting 5 seconds. Same error. What am I missing?

You can’t just post to the messages endpoint cold. You need a valid guestId and conversationId from the session creation flow first. Check the response from creating a session to grab those IDs before sending any text.