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.
Selling across Europe and the UK means every order has to answer one question before a price is final — and the answer depends on two addresses, a postcode, and whether a VAT number is real. How aiku validates tax numbers against VIES and HMRC (with retries, rate limits and an audit trail), and the decision tree that turns a shipping address into a tax category, Canaries and Madeira included.