A steam locomotive from 1993 broke my yarn test

This post details a deep dive into a persistent testing failure within Cloudflare's internal Backstage instance on Linux, characterized by a consistent 27-second timeout leading to a cryptic '[Error]'. The troubleshooting process involved extensive use of shell history, Jest flags, and ultimately `strace`, revealing an underlying system-level issue related to `epoll_wait` and `SIGCHLD` signals, potentially linked to older system components or configurations. This investigation highlights the challenges of maintaining robust development environments and the importance of low-level system analysis for debugging.