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.