cookbook proof · duplicate-payment-guard

Duplicate payment

An AP agent retries a $10K payment ten times on a flaky connection.

OpenClaw PAY_INVOICE

without kiff $100,000 10 debits on one invoice. Every retry pays again.

PAY_INVOICE state-aware gate ↓

with kiff $10,000 1 debit allowed. 9 retries refused.

1 Agent proposes PAY_INVOICE on a Invoice.

2 KIFF reads the Invoice's current state — before anything runs.

3 First call: state allows it → executed, receipt signed.

4 State is now PAID → every repeat refused, receipt signed.

The scenario

An agent pays a $10,000 invoice. A flaky connection drops the success response, so the transport retries the same call ~10 times. Each call is individually legitimate — same invoice, same amount — but only the first should ever debit.

Why it was refused

After the first debit the invoice advances to PAID. PAY_INVOICE is allowed only while the invoice is PENDING, so every retry is refused with state_not_allowed. A state-aware gate stops the emergent repeat that no single call looks guilty of.