GitHub Fork a Repository and Create a Working Branch

arazzo: 1.0.1
info:
  title: GitHub Fork a Repository and Create a Working Branch
  summary: Fork a repository, resolve the fork's default branch tip, and create a working branch.
  description: >-
    The contributor onboarding pattern. The workflow forks a repository into the
    authenticated account, reads the default branch reference on the fork to
    obtain its tip commit, and then creates a working branch on the fork from
    that commit. Forking is asynchronous on GitHub, so the fork step accepts the
    documented 202 Accepted response. Every step spells out its request inline so
    the flow can be read and executed without opening the underlying OpenAPI
    description.
  version: 1.0.0
sourceDescriptions:
- name: githubReposApi
  url: ../openapi/github-repos-api-openapi.yml
  type: openapi
workflows:
- workflowId: fork-and-branch
  summary: Fork a repository then create a working branch on the fork.
  description: >-
    Forks the upstream repository, reads the fork's default branch tip, and
    creates a working branch from it.
  inputs:
    type: object
    required:
    - githubToken
    - owner
    - repo
    - defaultBranch
    - workingBranch
    properties:
      githubToken:
        type: string
        description: A GitHub token with repo scope, passed as a Bearer credential.
      owner:
        type: string
        description: The account owner of the upstream repository to fork.
      repo:
        type: string
        description: The name of the upstream repository to fork.
      defaultBranch:
        type: string
        description: The default branch name of the fork to branch from, without the heads/ prefix.
      workingBranch:
        type: string
        description: The working branch name to create on the fork, without the heads/ prefix.
  steps:
  - stepId: forkRepository
    description: >-
      Fork the upstream repository into the authenticated account. The fork is
      created asynchronously and returns 202 Accepted.
    operationId: createFork
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.githubToken
    - name: owner
      in: path
      value: $inputs.owner
    - name: repo
      in: path
      value: $inputs.repo
    requestBody:
      contentType: application/json
      payload:
        default_branch_only: true
    successCriteria:
    - condition: $statusCode == 202
    outputs:
      forkOwner: $response.body#/owner/login
      forkName: $response.body#/name
  - stepId: getForkDefaultRef
    description: >-
      Read the default branch reference on the fork to obtain its tip commit
      SHA.
    operationId: getReference
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.githubToken
    - name: owner
      in: path
      value: $steps.forkRepository.outputs.forkOwner
    - name: repo
      in: path
      value: $steps.forkRepository.outputs.forkName
    - name: ref
      in: path
      value: "heads/$inputs.defaultBranch"
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      tipSha: $response.body#/object/sha
  - stepId: createWorkingBranch
    description: >-
      Create the working branch on the fork from the default branch tip SHA.
    operationId: createReference
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.githubToken
    - name: owner
      in: path
      value: $steps.forkRepository.outputs.forkOwner
    - name: repo
      in: path
      value: $steps.forkRepository.outputs.forkName
    requestBody:
      contentType: application/json
      payload:
        ref: "refs/heads/$inputs.workingBranch"
        sha: $steps.getForkDefaultRef.outputs.tipSha
    successCriteria:
    - condition: $statusCode == 201
    outputs:
      workingRef: $response.body#/ref
  outputs:
    forkOwner: $steps.forkRepository.outputs.forkOwner
    forkName: $steps.forkRepository.outputs.forkName
    workingRef: $steps.createWorkingBranch.outputs.workingRef