Short write‑ups of problems we hit running a real commerce operation and what we changed in the code because of them. No product announcements; just the reasoning.
A million invoices and fifty thousand credit notes, and the rule that governs all of them: an invoice is a frozen picture of an order at the moment it was billed, and nothing that happens later — a price change, a tax change, a product rename — can move it. How invoices are minted from orders, how credit notes reference the lines they return, how a paid status is derived rather than set, how invoices are categorised for the accountants, and how a PDF, an e‑invoice and an export all read from the same rows.