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.
We had an attribution feature for years and it had credited 0.08% of customers. Here is what was wrong, what we rebuilt — twenty channels, three email channels, ROAS and CAC with real costs, a per-customer journey — and the one invariant we now check after every change.
Every storefront page sends one small request to our own endpoint — not to a third party. From it: visitors, sessions, page views, country, device, referrer, the traffic source that becomes attribution, registration and add‑to‑basket conversions, "who is on the site right now", product interest per customer, and the list of most‑visited pages that decides what the cache warmer warms. Why a beacon that fires on cached pages was the only design that could work, how bots are filtered, and what we deliberately do not collect.
Fifty‑five kinds of email, one pipeline. How a newsletter to a hundred thousand people is prepared, sent through Amazon SES from a queue, tracked back event by event through SNS webhooks — delivered, opened, clicked, bounced, complained — attributed to the order it caused, and kept from becoming the retry storm that once throttled us at 1,700 calls a second.