Exercises 21 · Overdue Invoice Chaser

Start from workflow/starter.json (triggers, Stripe fetch, normalization) or your finished lesson workflow.

Exercise 1: Pause when the customer replies

Task: When a customer replies to a reminder, pause that invoice for 5 days and forward the reply to the owner.

Done when: replying "we'll pay Friday" to a reminder pauses chasing (ar/status shows paused_until) and the owner gets the reply.

Hint

Every subject contains the invoice number. A Gmail Trigger on replies (subject:invoice -from:me) can extract it with a regex, but the pause API needs the Stripe invoice id: keep a number → id map in static data (write it in plan.js) or look it up with Stripe GET /v1/invoices/search.

Exercise 2: A Google Sheets source

Task: Support businesses without Stripe: read open invoices from a sheet with columns id, number, customer, email, amount_remaining, currency, due_date, status, pay_url.

Done when: the scheduled run chases invoices from the sheet, and marking a row paid stops the reminders.

Exercise 3: Stripe pagination

Task: Fetch all open invoices, not just the first 100.

Done when: with more than 100 open invoices, open_invoices matches Stripe's count and has_more is false.

Stretch: Slack summary

Post the weekly summary to a Slack channel as well, with the largest overdue invoices as a list.