Which failure modes should a buyer probe when evaluating schedule handling?

Build or request tasks that target each of these, and report results per failure mode and not only as one total.

- **Rounding drift:** instalments no longer sum to the balance after a split, or the last payment absorbs the error in the wrong direction. - **Altered history:** paid or delivered items are edited when only future items should change. - **Wrong policy version:** an older or newer rule is applied because the effective date was misread. - **Authority breach:** the model approves or waives something its role cannot, or skips a required approval. - **Missed side effects:** a mandate, booking or notice linked to the schedule is left unchanged. - **Invented facts:** the model cites an approval, balance or clause that does not exist in the supplied records. - **Over-escalation:** the model refuses or escalates cases that policy allows it to complete. - **Order errors:** actions are correct but taken in a sequence the policy forbids, such as editing before cancelling a debit.

For each mode, ask for at least a few seeded variants with different amounts and dates, so a pass is not the result of memorising one case. Review failed episodes by hand to confirm the expected answer is right.