Closing Web Messaging session via API returns 403

The docs state: “Use the PATCH /api/v2/conversations/{conversationId} endpoint to update conversation attributes.” I’m trying to programmatically close a Web Messaging session from our backend service. The goal is to trigger the end-of-chat flow without user interaction.

Here’s the payload:

{
 "status": "closed",
 "routing": {
 "state": "closed"
 }
}

The response is a 403 Forbidden. The token used has the conversation:write scope. I’ve verified the conversation ID is correct and active. Other endpoints work fine with this token. The error body is empty. It’s not a permission issue on the token itself since I can read the conversation details. The docs don’t mention any special requirements for closing Web Messaging channels specifically. I’ve tried setting status to closed and routing.state to closed. Both result in 403. I’ve also tried adding mediaType to the payload, but that didn’t help. The conversation is still in queued state. I need to close it to stop the queue timer. Is there a specific attribute I’m missing? Or is this a known limitation for Web Messaging?