ENGINEERING STAGE 02
Type it, then reject bad writes.
Give product documents one shared typed shape and reject writes that do not match with known errors.
Complete when
The application and write boundary share the intended contract, and invalid writes are rejected rather than merely typed in an editor.
Not done if
Generated types with no reject-on-write behavior, or a type definition that the write path can bypass.
Evidence before advancement
Advance only when the running product and its repository demonstrate the stage’s done condition. Files that happen to exist are not proof by themselves, and completing one stage is not permission to start the next from the same job.
Track boundary
This work is Engineering Foundation, not a design-system stage. Do not add it to the From Prototype tracker or use it to relabel design-system Coverage.