Every cart in flight is a row with a stopwatch on it

Launch minute. Checkout is either fine or it isn't, and the dashboard that would tell you is a p95 chart that updates in a minute.

GET /api/v1/exec/monitor/active-requests returns every script request in flight right now: scriptPath, executionId, clientIp, method and URL, startedAt, elapsed milliseconds. At 10:02 there are forty-one rows for checkout.ts, most under a second. Three are past twelve seconds, same URL, same handler. You have their execution IDs to chase in the handler's logs, and @concurrent on that script already caps how many more can pile up behind them.

Observability during a flash sale used to mean a tracing vendor, an agent, and a sampling rate. Here it's the runtime's own list of what it's doing, unsampled, refreshed as fast as you can press enter.