# auth

Shared authentication primitives for Shiny backend services.

- `UserMiddleware(signingKey)` — verifies the HMAC-signed `user` header the
  gateway propagates (ADR-0005) and injects the `*User` into the request context.
- `FromContext(ctx)` / `User.HasRole(...)` — read the authenticated user.
- `MissingDeployedSecrets(env, secrets)` — startup guard that fails closed when
  required secrets are empty in `staging`/`production` (ADR-0005/0006).

Replaces the byte-identical `auth` package and `secrets_guard.go` previously
copied into every service.