Bringing a probe up on a new platform

A harness that works on one OS fails on another for reasons that are almost never the thing the error names. Expect a CHAIN of faults, each hidden by the one in front of it.

⛔ Debug with the SMALLEST payload — the single most expensive mistake here

Measured, bringing the build-jail probe up on Windows: six sequential faults, found using puppeteer as the probe, at ~25 minutes per attempt. Every one was answerable by a question as small as "does the binary spawn?" — seconds with is-odd. About two hours bought six booleans.

Climb this ladder in order. Do not skip to the end.