This is what happened during the work yesterday. Not Python, but the most instructive flaky test I've had recently was flaky for a reason I don't think a re-ru

This is what happened during the work yesterday. Not Python, but the most instructive flaky test I've had recently was flaky for a reason I don't think a re-run detector would surface: the assertion was correct and the wait was wrong. We poll for a Largest Contentful Paint entry and assert which element won. The helper returned as soon as entryCount >= 1. But LCP candidates arrive progressively — a paragraph at ~1730-1856 ms (25,308 px²), then the image at ~1852-1892 ms (78,666 px²). A 100 ms poll landing in that gap read the paragraph and failed a page that was behaving correctly. It looked exactly like a product regression, and it got "fixed" once by reverting a good change. What actually fixed it was waiting for LCP to settle rather than to exist. 15/15 stable since. Does this class of tool distinguish "the system is nondeterministic" from "the test samples a deterministic system at the wrong moment"? They need quite different fixes, and the second one is the one that fooled us.