Test a Flowise refund agent in 10 minutes

1 · Before you start

You need a Flowise chatflow (or Agentflow) that answers billing questions, reachable over public HTTPS — Flowise Cloud or self-hosted. Remove any Stripe credentials or Stripe tools from it: with COLVO the chatflow only proposes a refund, and COLVO executes it.

2 · Create four Flowise variables

In Flowise open Variables and create colvo_operations_url, colvo_agent_key, colvo_mandate_id and colvo_source_request_id with any placeholder value. COLVO replaces them for every test conversation through the prediction API.

In the chatflow’s settings, allow override config for sessionId and vars — otherwise Flowise ignores what COLVO sends.

3 · Add the colvo_propose tool

Add a Custom Tool named colvo_propose with two string inputs, action and parameters, attach it to your agent, and paste:

// Custom Tool "colvo_propose" — inputs: action (string), parameters (string, JSON)
//   refund: action "refund.create",       parameters {"payment_id":"pi_…","amount_minor":5000,"currency":"eur"}  (cents, a number)
//   cancel: action "subscription.cancel", parameters {"subscription_id":"sub_…","mode":"period_end"}  (or "immediate")
//   pause:  action "subscription.pause",  parameters {"subscription_id":"sub_…","resumes_at":"2026-12-12"}  (no resumes_at = no end date)
//   resume: action "subscription.resume", parameters {"subscription_id":"sub_…"}
//   undo:   action "subscription.cancel_undo", parameters {"subscription_id":"sub_…"}  (keep a plan whose cancellation is scheduled)
//   plan:   action "subscription.change_plan", parameters {"subscription_id":"sub_…","price_id":"price_…","at":"now"}  (or "period_end")
//   coupon: action "coupon.apply", parameters {"subscription_id":"sub_…","coupon_id":"WINBACK20"}
//   old invoice refund: parameters {"invoice_id":"in_…","amount_minor":2900,"currency":"eur"} instead of payment_id
const res = await fetch($vars.colvo_operations_url, {
  method: 'POST',
  headers: {
    authorization: 'Bearer ' + $vars.colvo_agent_key,
    'idempotency-key': $vars.colvo_source_request_id + ':' + $action,
    'content-type': 'application/json',
  },
  body: JSON.stringify({
    mandate_id: $vars.colvo_mandate_id,
    source_request_id: $vars.colvo_source_request_id,
    action: $action,
    parameters: JSON.parse($parameters),
  }),
});
const op = await res.json().catch(() => ({}));
if (!res.ok) return JSON.stringify({ decision: 'ERROR', error: op.error, message: op.message }); // never tell the customer it is done
return JSON.stringify({ decision: op.decision, reasons: op.decision_reasons });

Then add to the system prompt: “Never tell the customer an action is done unless colvo_propose returns ALLOW.”

4 · Connect it in COLVO

Open your project → Connect your agent → Flowise. Paste your Flowise address and the chatflow ID (from the chatflow’s API Endpoint dialog), and the Flowise API key if the chatflow has one. Leave “account facts” on: COLVO adds the customer’s payment and subscription ids under each message, so the model can use them in the tool call.

Press Test connection.

5 · Run the suite

Press Run suite. Every test is a new Flowise session, so conversations never mix, and COLVO checks the result in its own simulated Stripe — not in the reply. Next: read the verdict.