The toll plaza's internet died. The barrier still opened.

transcript

Midnight. A toll plaza's fibre link gets cut. Trucks keep coming. The barrier keeps lifting. Who pays?

12:31 am. Rajesh's truck rolls through. The barrier lifts. His phone stays silent. No debit. Nothing. 9:14 the next morning. Buzz. 845 rupees. Nine hours late.

No network. So the lane uses what it already holds. A signed tag it can verify offline. A local list of bad tags. Then it writes the crossing to an outbox. First. Only then does the barrier lift. When the link returns, it sends the oldest first.

NPCI's rule: reach the switch within 15 minutes. Rajesh's crossing is nine hours late. Still processed. But if his wallet can't cover it, the issuer can charge it back. The plaza carries that risk. After 3 days? Declined outright.

Refuse late crossings, and every fibre cut is lost money. Accept them forever, and no balance means anything. So late is priced. Not refused.

Full breakdown in the lecture.