Xiuhpohualli (Aztec Year Bearers & Calendar Round) (阿茲特克太陽年)

THE XIUHPOHUALLI — the Aztec solar year and the 52-year CALENDAR ROUND: every year named by a bearer (1–13 + Reed, Flint, House or Rabbit), eighteen veintenas plus the five hollow nemontemi, and the XIUHMOLPILLI — the binding of the years, when every fire in the Valley of Mexico was extinguished and the New Fire drilled atop Huixachtlan. THE BEARER SYSTEM IS A THEOREM WEARING FEATHERS, asserted at load: 365 ≡ 1 (mod 13) and ≡ 5 (mod 20) force the progression, and the +5 orbit closes on exactly four signs — only Reed, Flint, House and Rabbit can ever bear a year. THE CONQUEST CHAIN AS LAWS: five witnessed years, one formula — 1506 = 1-Tōchtli (the New Fire Moctezuma postponed), 1507 = 2-Ācatl (the last binding ever, Codex Borbonicus), 1519 = 1-Ācatl (Cortés arrives, the Quetzalcōātl prophecy year), 1520 = 2-Tecpatl, 1521 = 3-Calli (Tenochtitlan falls). The Calendar Round identity 52×365 = 18,980 = 73×260 proven; Caso's day anchor (13 Aug 1521 Julian = 1-Cōātl) cross-locked against the Maya engine on the shared GMT-584283 correlation. Post-1507 bindings labeled PROLEPTIC — the conquest ended the rite; the year-start dispute (Caso vs Tena) disclosed and per-day veintena placement deferred by name. Mesoamerican becomes six systems. Pure compute, no LLM.

Cost: 1 TIAN Points per call. tRPC procedure xiuhpohualli.year.