API Evangelist enhancements for the Fusio system API

# OpenAPI Overlay capturing API Evangelist enhancements to openapi/fusio-system.json
# The original document is never mutated. Apply with an Overlay 1.0.0 processor.
overlay: 1.0.0
info:
  title: API Evangelist enhancements for the Fusio system API
  version: 1.0.0
x-generated: '2026-08-29'
x-method: generated
x-source: openapi/fusio-system.json (harvested from https://demo.fusio-project.org/system/generator/spec-openapi?filter=system)
extends: openapi/fusio-system.json
actions:
  - target: $.info
    description: >-
      Add the contact, licence and terms the generated document omits. Fusio generates its OpenAPI
      live from the running instance and the generator emits only title, description and version,
      so a consumer of the raw document has no way to reach the maintainer or read the licence.
    update:
      contact:
        name: Fusio Project
        url: https://www.fusio-project.org/
        email: security@fusio-project.org
      license:
        name: Apache-2.0
        url: https://github.com/apioo/fusio/blob/master/LICENSE
  - target: $
    description: >-
      Point the document at the project documentation. The instance-generated spec carries no
      externalDocs at all.
    update:
      externalDocs:
        description: Fusio documentation
        url: https://docs.fusio-project.org/docs/architecture
  - target: $.info
    description: >-
      Record which API Evangelist artifacts were derived from this contract, so a downstream reader
      can find the error catalogue, conventions, scopes and tool crosswalk that go with it.
    update:
      x-apievangelist-artifacts:
        authentication: authentication/fusio-authentication.yml
        scopes: scopes/fusio-scopes.yml
        errors: errors/fusio-problem-types.yml
        conventions: conventions/fusio-conventions.yml
        lifecycle: lifecycle/fusio-lifecycle.yml
        rate_limits: rate-limits/fusio-rate-limits.yml
        data_model: data-model/fusio-data-model.yml
        mcp: mcp/fusio-mcp.yml
        tool_crosswalk: mcp/fusio-tool-crosswalk.yml
        conformance: conformance/fusio-conformance.yml
  - target: $.info
    description: >-
      Record the undocumented response headers every Fusio instance emits, verified live. They are
      absent from the generated document and from the documentation, but an agent can rely on them.
    update:
      x-response-headers:
        X-Request-Id: UUID correlating to the instance request log
        X-Operation-Id: the operationId that served the request
        X-Stability: 'the lifecycle state of that operation - experimental | stable | deprecated | legacy'
        RateLimit-Limit: emitted when a rate allocation matches the request
        RateLimit-Remaining: emitted when a rate allocation matches the request
  - target: $.info
    description: >-
      Flag the contract-quality gap this document has, so it is recorded rather than silently
      inherited: every operation declares only wildcard 4XX and 5XX responses, so no per-operation
      failure mode is machine-readable.
    update:
      x-known-gaps:
        - Every operation declares only 4XX/5XX wildcard responses carrying Common_Message.
        - No operation declares a concrete 401, 404 or 429 response.
        - The "title" field returned on every live error body is absent from the Common_Message schema.
        - No response examples are present in the document.