A reply of “qad qadaytukaha” follows “li ʿalayka alf.” What is the best analysis?

Kitab al-Iqrar: Debt and Trust, Admissions by Reply, and Deferred Debts

• No admission, so the case ends
• Admission of an earlier debt plus separate allegation of payment
• Payment conclusively proved without evidence
• It is only an admission of trust