Book: TypeScript in Production Also by me: The TypeScript Library — the 5-book collection My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub Imagine a downstream payment service starts misbehaving in the middle of the afternoon. Latency on a single endpoint goes from 80ms to 6 seconds. The provider has not declared an outage. Your service keeps calling it on every checkout, because every call still completes — slowly, with a mix of timeouts and 502s. A few minutes later your event loop is saturated. The queue of pending requests on your Node process is climbing past 4,000. Healthy endpoints in the same service are now timing out, because their handlers cannot get scheduled. Your p99 for every route on the service is over five seconds.…