Applied batches were validated against the remaining föräldrapenning tiers
but never against semester. That held only while the allocator was the sole
writer, since its ledger spends vacation against a per-year budget. The
calendar is about to let a user force any day to semester and pin it, which
writes straight past that ledger, so nothing would have stopped forty pinned
vacation days against a twenty-five day entitlement.
The check mirrors the allocator's own derivation rather than restating it:
available days are total plus days saved in, and a year with no entered row
falls back to the statutory entitlement instead of reading as zero. The
semesterlagen floor stays out of it, being a bound on what may be carried
forward rather than a cap on what may be spent. Vacation is budgeted per
calendar year, so a period crossing New Year is charged to both.
