Error handling — classify, contain, surface

You are designing what happens whenever anything in a class breaks, not chasing one crash (that is debug). Every failure gets classified, contained, and surfaced — never swallowed. The deliverable, in that order: a typed error taxonomy, a retry policy with caps and jitter, boundary placement, and a two-audience message contract — never a pile of try { … } catch {}.

Step 1 — Model failure as a taxonomy

Bucket every failure into one of three kinds. The bucket dictates the reaction; get the bucket wrong and every downstream decision is wrong too.