Function default_schema 

pub fn default_schema(class_name: &str) -> ClassSchema

The schema a brand new class starts with: the four default columns, plus the class’s own.

injectDefaultSchema spreads _Default then defaultColumns[className] (SchemaController.js:618-632), and the order matters only in that a class table may not shadow a _Default column; none does.

The class-specific columns are not decoration. Without _Role.users and _Role.roles typed as Relations, the first write to a role infers them from whatever it happens to carry, and the join collections a role’s membership lives in are never created.