👋 Hey {{first_name|there}},
Why this matters / where it hurts
You add one field to an event and nothing crashes. At first. A week later a consumer’s dashboard is blank and no one knows why. The schema drift was “small” so it did not get a plan. Incidents at odd hours follow.
I have shipped changes like that. It felt harmless, maybe even obvious. Then a silent cast error or a missing default turned into a support ticket. We fixed the code and moved on. Until the next time.
A data contract writes down what an event is, who owns it, which changes are allowed, and how consumers validate at the edge. It turns schema changes into a routine you can rehearse.
🧭 Mindset shift
From: “Producers publish JSON and consumers cope”
To: “Events have contracts, and evolution follows a small set of rules”
Why it matters
Events live longer than their authors intended. Without a contract, every consumer re-discovers the shape and invents their own fixes. With a contract, you get two simple habits that prevent most drift.
Two rules to start
Producers own the schema and publish a validation policy that runs at the edge
Changes follow expand first and contract later with a deprecation date