What happens when one remittance covers three invoices and falls short because of a dispute?

A billing officer at a commercial water utility receives payment PAY-5521 for 4,820.00 from a property manager. The remittance note lists INV-3301, INV-3302 and INV-3307. They are for 1,900.00, 1,600.00 and 1,640.00, a total of 5,140.00. INV-3302 includes a 320.00 meter-read charge flagged on CASE-0412.

The agent in the environment can call `get_remittance`, `list_open_invoices`, `get_policy`, `apply_allocation`, `hold_unapplied` and `open_query`. It reads the note, sees that the 320.00 gap equals the disputed line, and checks the case. Policy says disputed amounts must not be treated as short-pays or written off by the billing officer.

The agent allocates 1,900.00 to INV-3301 and 1,640.00 to INV-3307 in full, then 1,280.00 to the undisputed part of INV-3302. It adds a note to CASE-0412 recording the payment.

**State changes:** two invoices move to paid, one to part-paid with the disputed line preserved, the unapplied balance stays at zero, and the dispute stays open.

**Consequence of the shortcut:** applying the full amount to the oldest invoices first would have marked INV-3302 paid, weakened the dispute, and let the next reminder run suppress a legitimate query.

**What it teaches:** a grader that compares final invoice states and case notes catches this. One that only checks that the payment reached zero would not.