Contract-First API

A tRPC contract is not a document — it is code that both applications import.

The layers

• >>packages/schemas — zod schemas and z.infer types. The single source of truth.
• >>packages/api — tRPC routers built on top of those schemas.
• >>Frontend imports only type AppRouter and gets end-to-end inference.

Validation boundaries

1. >>Input validation — zod schemas on every procedure.
2. >>Data validation — db.json is parsed at startup, the server fails fast on invalid data.
3. >>Transport — queries use GET, mutations use POST, superjson for serialization.

If the schema does not run anywhere, it is documentation, not a contract.

Responses without envelopes

articles.list returns Article[] directly. tRPC already namespaces procedures by path, so { items: [...] } wrappers only add noise on the client.