Egyptian Days (Dies Aegyptiaci) (埃及凶日)

The medieval calendar's 24 unlucky days — two per month, marked 'D' at the head of every monthly calendar, shunned for new enterprises and above all for bloodletting — and the days that gave English the word DISMAL (dies mali → Anglo-Norman dis mal). Served from the mnemonic verse's own encoding: each month names one day counted from its START and one from its END ('Iani prima dies et septima fine timetur' — January's 1st, and the 7th-from-end = the 25th), a law this engine derives all 24 dates from and asserts against the standard double-sourced list at load. Check any date for membership (and which of the pair it is), get the next Egyptian day, or list a month with its verse arithmetic. The manuscript layers that vary by recension — the attached unlucky hours, the variant lists — are disclosed, never blended; Carlyle's 'dismal science' descends from this very calendar. Medieval calendar history served for reflection, not advice.

Cost: 1 TIAN Points per call. tRPC procedure egyptianDays.check.