Every language has a hash map. They all promise O(1) lookups. They all have surprising failure modes the docs don't talk about: hash collision attacks, mutable keys that become unreachable, iteration order that bites you, and 100x slowdowns from a few unlucky inputs. Knowing how they work under the hood is the difference between trusting them blindly and using them well.
Engineering Craft
TypeScript, CI/CD, databases, observability -- the skills that make code production-ready.
