72 Micro-Seasons (七十二候) (七十二候)

七十二候 — the East Asian year at its finest grain: each solar term split into three pentads of about five days, the seasonal layer Japanese design culture never stopped loving (東風解凍, the east wind melts the ice; 桜始開, the first cherry blossoms; 款冬華, the butterbur buds beneath the snow). TWO NATIONAL LISTS SERVED SIDE BY SIDE AND NEVER BLENDED: Japan's 略本暦 revision (every pentad with name, READING and meaning — はるかぜこおりをとく) and the classical Chinese 宣明暦 lineage (獺祭魚 — the otter lays out its fish like an offering); where they agree the agreement is visible, where they differ the difference is the point, and every response says which. THE COMPUTATION IS PURE GEOMETRY: each pentad opens when the sun reaches a 5°-multiple of ecliptic longitude (24 terms × 3 = 72 × 5°), computed on astronomy-engine — the published dates fall out on their own (立春初候 from 4 February; 桜始開 in late March). CROSS-VERIFIED: the Chinese column agrees with the independent 候 entries embedded in the 黃宗羲 witness the guaqi engine uses; 72 unique 5°-multiples, complete 初/次/末 triples for all 24 terms, and the famous anchors asserted at load; a year sweep tiles all 72 in tests. Seasonal poetry for cultural reference — the seasons themselves remain in charge. Pure computation, no LLM.

Cost: 2 TIAN Points per call. tRPC procedure pentads.current.