Four CI checks stayed green while broken — a team's account of silent pipeline failures

A software team discovered that four separate automated checks in a single repository had stopped being able to detect failures, yet continued showing green status in their CI pipeline. Among the issues was a GitHub Actions lint job where the tool's timeout matched the job's timeout, causing silent cancellations instead of diagnosable errors across three consecutive commits. A .gitattributes line-ending rule that appeared fixed locally left over 1,200 files with incorrect CRLF endings in pre-existing working trees, with CI and local environments reporting wildly different counts. A guard written to prevent the timeout misconfiguration from recurring falsely flagged a comment in the workflow file, because it scanned raw text without distinguishing code from prose. The team concluded that a check which cannot fail is more dangerous than a broken one, since silent false-positives eventually train developers to ignore alerts altogether.