Race demo

The scenario: Priya owes you ₹500. Ten settlement requests for the full amount hit the API at the exact same moment — a double-tap, a retried webhook, two devices.

Under weak isolation this is write skew: every request reads "₹500 outstanding", validates, and commits — you get "paid back" ₹5,000. Under CockroachDB's serializable isolation, exactly one can win.