GoCardless collections calendar and cash-in forecast

I want an app that shows me the money coming in over the next few weeks. Seeing what is on the horizon is the thing the GoCardless dashboard makes hardest, so keep this app squarely about scheduled future collections and how confident I can be in each one.

The main view is a month calendar. Each day cell shows the collections scheduled to be charged that day: a count and a total amount, split by currency. Build that forecast from two sources. First, upcoming payments on subscriptions: use GoCardless List Subscriptions to get the subscriptions, then Get Subscription on each active one to read its upcoming payments, which give a charge date and an amount. Second, payments that already exist but have not been collected yet: use List Payments and keep the ones still sitting in pending states such as pending_customer_approval, pending_submission and submitted, placing each on its charge date. De-duplicate where a pending payment and a subscription's upcoming payment describe the same collection, so a day is never double counted.

Show a running total for each week alongside the calendar rows, and a total for the visible month at the top, always split by currency and never summed across currencies. Let me page forward and back a month at a time, and default to the current month.

Clicking a day opens a detail panel listing the individual collections behind that number: payer name, amount, charge date, which subscription or payment it came from, and its current status. Pull payer details with List Customers so I see a human name rather than an identifier.

For every collection in the forecast, look at the linked mandate using List Mandates. If the mandate is not active, for example cancelled, expired, failed, or still pending customer approval or submission, flag that collection as at risk. Every total, per day, per week and per month, should show a banked figure and an at risk figure so I can see how much of the forecast is shaky rather than certain. In the day detail panel, say why each flagged item is at risk by naming the mandate status.

Add an "Export this month" button. It writes the forecast rows for the visible month to a Google Sheet using Append Values, one row per collection with charge date, payer name, amount, currency, the subscription or payment reference, the mandate status and the at risk flag, so I can drop it straight into the finance pack. Let me pick the spreadsheet and tab, and confirm how many rows were written.

Add a "Write the commentary" button that starts a background agent. The agent compares the forecast against what actually landed recently: it reads List Payouts and List Payout Items to see which collections made it into real payouts, and List Payments filtered to failed and cancelled statuses to see what fell over. It then writes a short cash-in note, a few paragraphs at most, covering how recent forecasts compared with reality, the main failure patterns it found, and what that implies for the month ahead. The note is written back into the app and shown alongside the calendar, with a timestamp and a history of previous notes so I can read the last one while a new one is being written.

Three rules to bake in. The charge date is not the payout date: bank debit takes several working days to settle, so make it obvious in the interface that the calendar shows when a payer is charged, not when money reaches my bank account. Cancelled and completed subscriptions must be excluded from the forecast entirely, so only active subscriptions contribute upcoming payments. Amounts come back from GoCardless as integers in minor units such as pence and cents, so convert and format them with the correct currency symbol and decimal places everywhere they are displayed or exported.