Python bug repair — Demonstration

A deliberately created Python debugging demonstration, not previous client work. Three amounts should total 35.60, but the faulty script outputs 23.10 because an extra next(rows) discards the first data record after csv.DictReader has already consumed the header. The repair removes that call and uses Decimal. The included check reproduces the defect, verifies 35.60, and checks single-record and header-only inputs. Source and run instructions are included. AI-assisted development with checked results.