5 posts tagged this topic.
A factory-telemetry simulator that replays four hours in 15,000-millisecond steps and again in 150,000-millisecond steps must produce a byte-identical event list, or every calibrated OEE band is only true at the speed you happened to demo it — a discrete-event scheduler makes the tick size irrelevant by design, and a test proves it rather than assuming it.
A duplicate-customer scan ran right after its own transaction returned, but on the website path that transaction was only a savepoint inside the caller's. A read-only audit, not the 1,319 tests already passing, found that bug and three more like it.
A Biome lint fix renamed a Playwright fixture's empty-object parameter to silence a dead-pattern lint error — a no-op for the function body, but Playwright reads that exact syntax shape to resolve fixture dependencies, and the rename crashed every end-to-end test before a single one ran.
AIDA's Settings AI Features form blocked Save with a "Select a model" error right after switching providers. The real defect sat two React commits away, inside a hidden native select Radix uses to bridge into native form submission — and it never raised an error of its own.
An AI agent blamed a failing Playwright test on Next.js response caching. I traced the code and blamed middleware. We were both wrong about the observation: the test's "anonymous" context was quietly authenticated. Two stacked bugs, two confident stories, and the re-run as the only reviewer that counted.