-- Unpaid flag --
  ok  exactly one student flagged
  ok  the unpaid one is flagged
  ok  remaining = 120000 due − 50000 verified (unverified ignored)
  ok  far midterm → not flagged yet
  ok  passed midterm → still flagged
-- Reminder queue --
  ok  one reminder queued
  ok  second run queues nothing (deduped)
  ok  Arabic message with amount
  ok  non-finance cannot queue

9 passed, 0 failed