generated: '2026-08-19'
method: derived
source: >-
  openapi/tum-campus-backend-openapi.yml (rpcStatus / protobufAny), openapi/tum-*-openapi.yml
  (NavigaTUM), plus live 2026-08-19 probes of the deployed endpoints. Derived from
  institution-operated contracts only.
x-operator: institution
surfaces:

- surface: TUM Campus App Backend API
  base_url: https://api.tum.app/v1
  model: google.rpc.Status
  detail: >-
    Every operation declares a `default` response bound to `rpcStatus` — the grpc-gateway rendering
    of google.rpc.Status: an integer `code`, a `message` string, and a `details` array of
    `protobufAny`. No per-status-code responses (400/401/404/429) are declared anywhere in the
    document, so a consumer cannot tell from the contract which failures are retryable.
  schema:
    code: 'integer (int32) — gRPC status code, not HTTP'
    message: string
    details: 'array of protobufAny ({ "@type": string, ...arbitrary })'
  observed:
  - url: https://api.tum.app/v1/canteen/allCanteens
    status: 501
    body: '{"error":"method ListCanteens not implemented"}'
    note: >-
      DEFECT — the published contract advertises Campus_ListCanteens but the deployment returns
      501 "method ListCanteens not implemented". The live error body is also NOT rpcStatus shape:
      it is a bare {"error": string}. The deployed error model and the contracted error model
      disagree.
  - url: https://api.tum.app/v1/openapi.json
    status: 404
    body: '{"error":"Not Found"}'
    note: 'Undocumented {"error": string} shape again; no rpcStatus, no problem+json.'

- surface: NavigaTUM
  base_url: https://nav.tum.de/api
  model: per-operation HTTP responses
  detail: >-
    The NavigaTUM contracts declare explicit response codes per operation rather than a single
    error envelope. Bodies are plain text or JSON depending on the endpoint; no RFC 7807
    problem+json is used anywhere.

gaps:
- >-
  Neither institution-operated surface publishes an RFC 7807 / RFC 9457 problem details media type.
- >-
  Neither publishes a stable machine-readable error code registry that a client could switch on.
- >-
  The Campus App backend contract declares only 200 and `default`; the operational reality includes
  at least 404 and 501 with a different body shape than the one contracted.