How to initiate cobrowse session via Conversations API in C#

I’ve been digging through the Genesys Cloud API docs trying to figure out how to kick off a cobrowse session programmatically from our custom agent desktop. The goal is to start a session when an agent clicks a button in our .NET app, but I can’t find a direct endpoint like /api/v2/conversations/cobrowse/start. I tried using the general conversations endpoint with a POST request to /api/v2/conversations/v2, setting the conversation type to cobrowse and passing the participant details in the JSON body, but it just returns a 400 Bad Request saying the conversation type is invalid. Here is the payload I’m sending with HttpClient.

var payload = new { 
 type = "cobrowse", 
 participants = new[] { 
 new { id = agentId, role = "agent" }, 
 new { id = customerId, role = "customer" } 
 }
};

The error response doesn’t give much detail other than the type being wrong. I know cobrowse exists in the UI and there are webhooks for session events, but initiating it via code seems missing or hidden behind a different method. Am I missing a specific header or is there a separate SDK method in the C# client I should be calling instead?