Email verification looks easy until you try to prove it works repeatably in CI. The happy path is obvious: create user, send email, click link, mark account verified. The fragile part is everything between the Node.js handler, the PostgreSQL transaction, and the mailbox your test inspects. In backend teams, I see the same mistake again and again: people confirm that an email showed up, then assume the auth flow is covered. It is not. A reliable test has to connect one signup request to one ve...