How do you change the shape of your data, or of an AI answer, without quietly breaking the parts that read it?
- Module
- 04/05
- To read
- ~5 min
A team renamed the “user_id” field in their user service’s response to “id” and deployed. All of their own tests passed. What do you think happened next?
In the module you make your guess first, then read what happened and why.
Consumer-Driven Verification (Pact)
Additive-Only Evolution
Lenient Parsing with Strict Emission (Postel’s Law)
Breaking Change Versioning Gates
A plan for changing data shapes safely
A spec for your own app, as a text file you download. The module also gives you the prompt for Claude Code, Codex or Antigravity, a checklist to check what it built, and recommended skills.
- API gateways
- Event-driven architecture