Problem 1: The terms are astronomical, the users are local. White Dew arrives when the Sun reaches 165° ecliptic longitude — a moment in time, like a solstice. In Tokyo it may fall on September 7, in New York on September 6. Users who emigrated expect "their" calendar to follow the sky, not their old hometown's newspaper. We compute term boundaries from solar longitude in UTC, then render in the user's timezone.

Problem 2: Tradition encodes latitude, users live everywhere. "Protect against morning chill" is advice tuned for the Yangtze basin. The same term means something different in Singapore or Stockholm. Our engine degrades gracefully: each term carries its principle (autumn dryness affects the lung system), and the daily recommendations adjust intensity by local climate signals, not by folklore copy-paste.

Problem 3: The two-hour clock. TCM maps the day into 12 two-hour blocks (shichen), each with an active meridian. Users ask "what block is it now?" and the honest answer requires deciding whether the block follows solar time, local clock time, or the timezone's reference meridian. We chose local clock time with solar-noon correction data exposed for users who care.

The general lesson: any heritage knowledge system, encoded naively, becomes either a museum (exact, unusable abroad) or mush (usable, meaningless). The engineering work is finding the invariants — astronomy, physiology, sleep timing — and letting culture-specific rendering hang off those.

SEASONS ships this as daily guidance in English, for users in any timezone.