Seasonal Counting Days (三伏・數九・土用) (三伏數九土用)

The East Asian almanac's SEASONAL COUNTING DAYS — the four folk layers that turn solar terms and ganzhi days into the year's thermometer, all in one call. 三伏, the dog days, by the 夏至三庚 rule (初伏 on the third 庚 day after the summer solstice, 中伏 on the fourth running 10 or 20 days, 末伏 on the first 庚 from 立秋) — VERIFIED against the published tables day by day: 2025's rare 30-day sanfu (初伏 7/20 庚寅, 中伏 7/30 庚子, 末伏 8/9 庚戌, the latest 入伏 in six decades) and 2024's 40-day year, both asserted at load, with the 30-or-40 total proven across sampled decades. 社日, the soil-god festivals (春社/秋社 = the fifth 戊 day after 立春/立秋). 數九, the nine nines of winter — 81 days from the solstice, with the 冬至逢壬 minority reckoning named, not blended. And 土用, the four earth-phases before the season gates (JST, as Japan reckons them), with the summer doyō's 丑の日 — the EEL DAYS — anchored to the published 2025 pair (7/19 + 7/31) and 2026's single 7/26. Solar terms from astronomy-engine, day pillars from lunar-javascript, CST/JST conventions applied per layer and stated. Folk seasonal reckoning for cultural reference — not weather forecasting or health advice. Pure computation, no LLM.

Cost: 2 TIAN Points per call. tRPC procedure seasonal.counts.