How do I connect Stripe invoices for AR collections?

Why the customer has to exist first

Stripe's Create an Invoice endpoint requires a customer parameter — the ID of the customer to bill — unless the invoice is a revision of an existing one (from_invoice). There's no way to create an invoice against a customer that doesn't exist yet; Stripe raises an error if the customer ID provided is invalid. For a Loopfour workflow, this means the AR sync has to create or look up the Stripe Customer before it ever calls createInvoice, not as an afterthought.

The path from draft to collected

A Stripe invoice starts in draft status the moment it's created and stays there until it's finalized — finalizing locks in the line items and amount, and generates the hosted invoice URL and PDF. From there, collection depends on collection_method: charge_automatically attempts payment against the customer's default source, while send_invoice emails the invoice with payment instructions and a due date instead. Loopfour's sendInvoice action covers the second path explicitly; voidInvoice handles the case where a draft or open invoice needs to be canceled before it's paid.

Where this sits relative to other AR tools in the matrix

Slack and Gmail, elsewhere in this matrix, can notify someone about an overdue invoice, but neither one actually issues or holds an invoice — they're notification channels layered on top of AR data that lives somewhere else. Stripe's invoice actions are the AR system itself for whatever revenue flows through Stripe: the invoice, its line items, its status, and its payment collection all live on the Stripe side, which is why getting the customer relationship right at connection time matters more here than it does for a channel that's just relaying information.