> Trying to define models (as Taxi defines them) statically is often a source of hidden technical debt as models change over time and different teams in differe

> Trying to define models (as Taxi defines them) statically is often a source of hidden technical debt as models change over time and different teams in different parts of an org can't agree on what a model should contain. I completely agree. My view (and the view of Taxi) is that Types should be shared by teams, but never models - for exactly the reasons you've outlined. Systems need a way of describing their data as a composite of those scalar types - that's what Models provide. Field names are part of that contract, as they tell you structurally where information is. Types describe semantically what that information contains - you need both to semantically document the contract of data. However, if multiple teams start sharing models, you end up with exactly the `PersonButWithoutSSN` situation you've described, which is a BadThing. Our vision is to let data consumers to semantically describe the data they require, in the format they want it. If that doesn't align with how a producer is emitting it, or requires stitching data from multiple producers, that's OK - tooling can enable that, provided you have rich semantic schemas.