Audience asks how to handle evolving event schemas. Ladd: it's a difficult situation. In a monolith, versioning is usually the only option — publish new versions and branch on read. In microservices, services are small enough that you can rebuild the service, transform old events into commands, and feed them into the new version (still a lot of work). His first answer: don't make the mistake — and learn from mistakes like the airline industry does, instead of reflexively switching programming languages, tools, or jobs.