H1 Mn-Al-C GGen exploration candidate (action 01a06e15-0cb2-702f-bc28-fec045530a28, e_above_hull 59 meV/atom). Validated 2026-09-04: parsed, reduced formula Mn5Al3C, 9 sites, SG I4mm (107) (symprec 0.01 and 0.1), density 5.78 g/cm3, min pair distance 1.89 A, ordered.