She tapped Place order twice. The shop got one order.

transcript

She paid. The spinner kept spinning. So she tapped again. Two companies, no shared database. Why only one order?

Pune, Dhanteras evening. She pays for a brass thali. Her screen says: confirming your order with the seller. She taps place order again. Two minutes later: placed.

Here's the trick. Her app creates the order id. O-77. Unique across the whole network. Every retry carries it. So the second confirm finds the same order. Just an ACK.

But the seller app doesn't pack it yet. It holds it. That's the ONDC rule. Release only after her app acknowledges. But here's the catch. What if someone goes silent? No answer to confirm? Her app cancels with 999, and refunds. Her app never acknowledges? The seller app cancels with 998.

Both sides reach the same answer. Without talking. Name it once. Hold it. Release when both have heard.

Full breakdown in the lecture.