An HVAC company in the Midwest gave their AI agent a refund tool in February with one guardrail: max_refund_amount: 500 . Sensible. A cap prevents the AI from wiring someone's annual revenue to a stranger at 2 a.m.

In April, a customer's upstairs unit failed eleven days after a $1,840 repair. She texted at 9:40 p.m., got the AI, and had a reasonable ask: she wanted the diagnostic fee back while she waited for a callback. The AI refunded $380. She asked about the parts. The AI refunded $460. She asked whether the labor was included. The AI refunded $500 — the cap, exactly. She asked again, phrasing it as a follow-up on the same issue. The AI refunded $500 again. Then $480.

Total: $2,320 against a $1,840 invoice, issued in nineteen minutes, at night, with no human in the loop. Every single call was under the cap. The cap worked perfectly. The customer got more money back than she paid.

The failure wasn't the limit.…