triage

A whole rack failing at once is a shared dependency, which narrows the causes to four before anyone touches anything. What the out-of-band network tells you in the first minute, why the order of restoration matters, and the decision about liquid cooling that has to be made before power returns.

A repository page and a config file contain everything needed to say whether this is a weekend project or a quarter. The nine fields that matter, the two that change the answer by an order of magnitude, and the go or no-go check that comes before any of the arithmetic.

The first move is not technical. It is deciding who runs what, because one person serially debugging three incidents is slower than three people in parallel and much slower than one person coordinating. The ordering rule, and the two things that outrank everything else.