Two historical application outcomes share the same optional-file ENOENT. With the required file absent the child exits 7; after only the required file is restored it exits 0. An error line alone does not establish the cause of failure.

Strace explains selected system-call boundaries

Strace observes system calls and signals at the boundary between a selected Linux process and the kernel. It can reveal attempted paths, arguments, return values, and errors without rebuilding the program. That evidence is useful when application logs omit an operation, but it does not expose every user-space decision or automatically identify which failed call caused the application’s final outcome. ...

February 14, 2028 · 5 min · XB Field Notes
Nine encoded history states show good revisions 0–3 and 5–6, skipped 4, and bad 7–8, with a pointer to first bad 7. Exit 200 aborts rather than labels. Positions do not show probe order.

git bisect automates a regression search

Automated bisection repeatedly checks a revision and turns the result into a history decision. It can replace many manual checkouts with roughly logarithmic probes on a simple range, but the speedup depends on a trustworthy test. A wrapper that misclassifies missing tools or broken infrastructure can confidently identify the wrong commit. Designing the verdict contract is therefore part of debugging, not merely setup around the search. ...

July 7, 2027 · 5 min · XB Field Notes