Hugging Face Chat Completion with Model Discovery

arazzo: 1.0.1
info:
  title: Hugging Face Chat Completion with Model Discovery
  summary: Discover an available router model, confirm it exists, then run an OpenAI-compatible chat completion.
  description: >-
    Uses the Hugging Face Inference Providers router to list the models that are
    currently servable, verifies the requested model is present, and then sends
    an OpenAI-compatible chat completion request that is automatically routed to
    the best provider. The flow branches on whether the requested model is found
    in the catalog. 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: inferenceProvidersApi
  url: ../openapi/hugging-face-inference-providers-api.yml
  type: openapi
workflows:
- workflowId: chat-completion-with-model-discovery
  summary: Confirm a router model is available and run a chat completion against it.
  description: >-
    Lists router models, retrieves the requested model record to confirm it is
    servable, and then creates a chat completion using that model.
  inputs:
    type: object
    required:
    - hfToken
    - modelId
    - userMessage
    properties:
      hfToken:
        type: string
        description: Hugging Face access token used as a Bearer credential.
      modelId:
        type: string
        description: The model id to run the chat completion against.
      systemPrompt:
        type: string
        description: Optional system message that sets assistant behavior.
        default: You are a helpful assistant.
      userMessage:
        type: string
        description: The user message content to send to the model.
      maxTokens:
        type: integer
        description: Maximum number of tokens to generate.
        default: 256
  steps:
  - stepId: listRouterModels
    description: >-
      List the models currently available through the inference providers router
      so the requested model can be confirmed before billing a completion.
    operationId: listModels
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.hfToken
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      models: $response.body#/data
  - stepId: confirmModel
    description: >-
      Fetch the requested model record from the router to confirm it exists and
      is servable. Branches to the chat completion on success.
    operationId: getModel
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.hfToken
    - name: model_id
      in: path
      value: $inputs.modelId
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      confirmedModelId: $response.body#/id
    onSuccess:
    - name: modelConfirmed
      type: goto
      stepId: createChat
      criteria:
      - condition: $statusCode == 200
  - stepId: createChat
    description: >-
      Send an OpenAI-compatible chat completion request with a system and user
      message; the router selects the optimal provider automatically.
    operationId: createChatCompletion
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.hfToken
    requestBody:
      contentType: application/json
      payload:
        model: $steps.confirmModel.outputs.confirmedModelId
        messages:
        - role: system
          content: $inputs.systemPrompt
        - role: user
          content: $inputs.userMessage
        max_tokens: $inputs.maxTokens
        stream: false
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      completionId: $response.body#/id
      assistantMessage: $response.body#/choices/0/message/content
      finishReason: $response.body#/choices/0/finish_reason
      totalTokens: $response.body#/usage/total_tokens
  outputs:
    completionId: $steps.createChat.outputs.completionId
    assistantMessage: $steps.createChat.outputs.assistantMessage
    totalTokens: $steps.createChat.outputs.totalTokens