# debugging

At 6 a.m., Ubuntu auto-updated, restarted systemd-resolved, overwrote resolv.conf, and erased a gVisor sandbox’s DNS configuration. Bun/axios then mislabeled SERVFAIL as ECONNRESET—turning six correct behaviors into one nondeterministic Cowork outage.

Learning how programs die, detective-style. This is Part 1 of a three-part series: first, understand the anatomy — CPU, stack, return addresses, segfault — before you can investigate the crime scene and catch the killer. A quiz at every floor. Pass to proceed.

Autopsy trilogy, Part 2. Enter the core dump crime scene, learn the red zone and signal handler roles, then move from coroner to epidemiologist: use a year of citywide death records to solve the first bug, a poisoned well called a bad host.

The autopsy trilogy finale. The remaining 'return-to-null' murders all died during C++ exception unwinding — a teleport, not a normal return. The killer: an 18-year-old race in GNU libunwind, with a murder window one instruction wide (~100 picoseconds). Plus Fermi estimation to check the math.