GoCardless payer lookup for support and finance teams

Build me an internal app that my support and finance team opens whenever a payer emails us about their Direct Debit, so nobody has to be handed a GoCardless dashboard login just to answer a question.

The main screen is a search box over our GoCardless customers. I type a name or an email address and get back matching payers with their name, email and when they were created, using List Customers to fetch and filter, and Get Customer to load a single payer once I pick one. Searching should feel like the only thing on the page, because looking someone up is what people came here to do.

Opening a payer shows one page with a single timeline of everything about them. Their mandates and each mandate's current status from List Mandates. Their active subscriptions with amount and frequency from List Subscriptions. Every payment with its status, amount, charge date and, where it failed, the failure reason, from List Payments. Refunds already issued from List Refunds. And the bank account on file from List Customer Bank Accounts, showing only the last four digits alongside the bank name, never the full account number. All of these are filtered to that customer, and the payments and refunds read as one chronological story rather than five separate tables stacked on the page.

From a row I can act. Retry a failed payment with Retry Payment. Take a one-off payment against an existing mandate with Create Payment, where I enter the amount and a description. Issue a refund against a payment with Create Refund, full or partial. Cancel a subscription with Cancel Subscription. Reinstate a cancelled mandate with Reinstate Mandate. Every one of these sits behind a confirmation step that restates the payer, the amount in real currency and exactly what is about to happen, because these move real money. After an action succeeds, refresh that payer's timeline so the new state is visible immediately, and if GoCardless rejects the action, show the reason it gave in plain language rather than a raw error.

Add an Explain this account button on the payer page that kicks off a background agent. The agent reads the payer's full payment and mandate history through List Payments, List Mandates, List Subscriptions and List Refunds, works out the story of what actually happened and why, for example a mandate that was cancelled by the bank causing the last three payments to fail, and writes a plain English summary back into the app so it appears on that payer's page for anyone who opens it next. The agent also prepares a customer-ready reply and saves it as a Gmail draft with Create a Draft, addressed to the payer, explaining their situation and any next step. It never sends the email. A human reads the draft, edits it and sends it. While the agent is running, show that it is working on the payer page, and keep previous summaries so the team can see what was explained before.

Three things to bake in throughout. GoCardless amounts are integers in the smallest currency unit, so pence and cents, and must be formatted with the correct currency before anyone sees them. A failed payment can only be resubmitted three times, so each failed row should show how many retries remain and disable the retry button once they are used up. And bank debit takes several working days to clear, so pending is normal rather than broken, and the app should label pending payments in a way that stops people chasing a customer who has done nothing wrong.