Two hundred services exchange events and a field rename broke nine consumers last week. Design schema evolution.

A published event is an API with no version negotiation and consumers you cannot enumerate. The design is a registry that refuses an incompatible change at publish time, because after publication your options are all bad.

Grounded in researched DevOps, SRE and platform engineering interview loops, written to a senior-engineer editorial bar, and never padded to hit a word count.