Set Participant Data action dropping custom JSON payload in Go webhook handler

Architect & Flows
1

I’m building a Go service that intercepts Genesys Cloud IVR calls via a webhook. The goal is to update participant data dynamically based on external DB lookups before the call routes to an agent.

I’m using the Set Participant Data action in Architect. The webhook hits my endpoint, I fetch the data, and I POST back to the continueUrl provided in the request body.

Here’s the payload I’m sending back:

{
 "data": {
 "custom": {
 "customerId": "12345",
 "tier": "gold"
 }
 }
}

The HTTP response is 200 OK. No errors in the Genesys logs. But when I check the conversation in the UI or query the API later, those custom fields are empty.

I’ve verified the JSON structure matches the docs. I’m using application/json content type.

Is there a specific schema requirement for the Set Participant Data response that I’m missing? Or does it only support simple key-value pairs at the root level, not nested under custom?

Here’s the relevant Go snippet handling the POST:

func handleWebhook(w http.ResponseWriter, r *http.Request) {
 var req webhookRequest
 json.NewDecoder(r.Body).Decode(&req)
 
 // ... fetch data from DB ... 
 
 resp := map[string]interface{}{
 "data": map[string]interface{}{
 "custom": map[string]interface{}{
 "customerId": req.CustomerId,
 "tier": "gold",
 },
 },
 }
 
 w.Header().Set("Content-Type", "application/json")
 json.NewEncoder(w).Encode(resp)
}

The continueUrl is definitely being hit. I can see the request in my logs. Just the data isn’t sticking.