Single source of truth for TREK's API contracts, expressed as Zod schemas and consumed by both the server (request validation + inferred DTO types) and the client (typed requests/responses).

This package is part of the incremental NestJS + React 19 migration (see the "Brownfield Rewrite" board). It is intentionally dormant until modules start importing it — adding it changes nothing for users.

Rules

One folder per domain: src/<domain>/<domain>.schema.ts (+ .spec.ts).
Domain-agnostic building blocks live in src/common/.
A route is only considered migrated once its contract lives here.
Schemas are the source of truth; server DTOs and client types are inferred from them (z.infer<typeof schema>), never hand-duplicated.

Consumption (dev)

Both apps resolve @trek/shared to this package's TypeScript source:

Server (tsx): via paths in server/tsconfig.json.
Client (vite): via resolve.alias in client/vite.config.ts (+ paths for the type-checker).

Production packaging (Docker / workspace wiring) is introduced in card F2, when the server first depends on this package at runtime. Until then prod builds are untouched.

Not yet here

The canonical error envelope is finalised in card F5 (it must match TREK's current Express error responses byte-for-byte), so it is deliberately not invented in F1.