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.
3,300 tests against a real PostgreSQL with 800 tables, restored from a dump before every file, run in parallel on ten processes in CI and by a dozen people and their AI agents at once locally — without stepping on each other. No mocks of the schema, no synthetic repositories. How the TEST_TOKEN trick makes that possible, and the four ways such a suite goes flaky.