Chutes Chat Completions Streaming (HTTP + SSE)

asyncapi: '2.6.0'
id: 'urn:ai:chutes:llm:v1:chat-completions:sse'
info:
  title: Chutes Chat Completions Streaming (HTTP + SSE)
  version: '1.0.0'
  description: |
    AsyncAPI 2.6 description of Chutes' **chat completion streaming** surface.

    Chutes does not publish a public WebSocket API. The only asynchronous /
    event-style transport documented at https://chutes.ai/docs/examples/llm-chat
    is **HTTP Server-Sent Events (SSE)** delivered over the OpenAI-compatible
    REST endpoint (`POST /chat/completions`) at https://llm.chutes.ai/v1 when the
    request body sets `stream: true`. SSE is a one-way, server-to-client HTTP
    streaming channel; it is **not** WebSocket.

    Chutes is OpenAI-compatible, so the streamed events are `chat.completion.chunk`
    objects terminated by a `data: [DONE]` sentinel, identical in shape to the
    OpenAI streaming protocol. The request body itself (model, messages, etc.) is
    modeled in the companion OpenAPI document at `openapi/chutes-openapi.yml`.

    Chutes runs on Bittensor Subnet 64; an internal socket.chutes.ai service is
    used for miner/validator coordination but is **not** a documented public API
    and is not modeled here.
  contact:
    name: API Evangelist
    email: kin@apievangelist.com
    url: https://apievangelist.com
  license:
    name: API documentation - Chutes Terms of Service
    url: https://chutes.ai/terms
  x-transport-notes:
    transport: HTTP Server-Sent Events (SSE)
    protocol: https
    direction: server-to-client (one-way)
    mediaType: text/event-stream
    triggeredBy: 'POST https://llm.chutes.ai/v1/chat/completions with request body { "stream": true }'
    terminator: 'data: [DONE]'
    notWebSocket: true
    source: https://chutes.ai/docs/examples/llm-chat
defaultContentType: text/event-stream
servers:
  chutes-llm:
    url: llm.chutes.ai/v1
    protocol: https
    description: |
      Chutes' OpenAI-compatible REST base. Chat completion streaming is delivered
      as HTTP Server-Sent Events over this base when `stream: true` is set on the
      JSON request body. AsyncAPI 2.6 does not define a dedicated SSE protocol
      identifier; `https` is used here and the SSE transport is documented in
      `info.x-transport-notes` and on each channel.
    security:
      - bearerAuth: []
channels:
  /chat/completions:
    description: |
      Chat completion SSE stream. The client opens this channel by issuing
      `POST /chat/completions` with `Content-Type: application/json`,
      `Accept: text/event-stream` (implied), and a JSON body containing
      `stream: true`. The server responds with `Content-Type: text/event-stream`
      and emits a sequence of `data:` lines, each carrying one JSON-serialized
      `chat.completion.chunk` object, followed by a final `data: [DONE]` line.
    bindings:
      http:
        type: request
        method: POST
        bindingVersion: '0.3.0'
      x-sse:
        mediaType: text/event-stream
        eventField: 'data'
        terminator: '[DONE]'
    subscribe:
      operationId: streamChatCompletionChunks
      summary: Subscribe to streamed chat completion chunks (SSE).
      description: |
        After `POST /chat/completions` is issued with `stream: true`, the server
        emits an ordered sequence of SSE `data:` events. Each `data:` line
        either carries a JSON-serialized `ChatCompletionChunk` or the literal
        sentinel `[DONE]` marking end of stream.
      bindings:
        http:
          type: response
          bindingVersion: '0.3.0'
      message:
        oneOf:
          - $ref: '#/components/messages/ChatCompletionChunk'
          - $ref: '#/components/messages/StreamDone'
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: 'Chutes API key (cpk_)'
      description: |
        Chutes bearer token. Set the `Authorization: Bearer cpk_...` header on
        the `POST /chat/completions` request that opens the SSE stream.
  messages:
    ChatCompletionChunk:
      name: ChatCompletionChunk
      title: Streamed chat completion chunk
      summary: |
        A single SSE `data:` event carrying one JSON `chat.completion.chunk`
        object. Many of these are emitted per request, in order.
      contentType: application/json
      description: |
        Sent as `data: {json}\n\n` on the SSE stream. The JSON object's
        `object` field is always the literal string `chat.completion.chunk`.
        Fields follow the OpenAI-compatible chat completion chunk schema.
      payload:
        $ref: '#/components/schemas/ChatCompletionChunk'
      examples:
        - name: openingChunk
          summary: First chunk - establishes role
          payload:
            id: chatcmpl-abc123
            object: chat.completion.chunk
            created: 1750464000
            model: deepseek-ai/DeepSeek-V3-0324
            choices:
              - index: 0
                delta:
                  role: assistant
                  content: ''
                logprobs: null
                finish_reason: null
        - name: contentChunk
          summary: Token delta
          payload:
            id: chatcmpl-abc123
            object: chat.completion.chunk
            created: 1750464000
            model: deepseek-ai/DeepSeek-V3-0324
            choices:
              - index: 0
                delta:
                  content: 'Hello'
                logprobs: null
                finish_reason: null
        - name: finalChunk
          summary: Final chunk - finish_reason set
          payload:
            id: chatcmpl-abc123
            object: chat.completion.chunk
            created: 1750464000
            model: deepseek-ai/DeepSeek-V3-0324
            choices:
              - index: 0
                delta: {}
                logprobs: null
                finish_reason: stop
    StreamDone:
      name: StreamDone
      title: Stream terminator
      summary: |
        The literal SSE event `data: [DONE]` that marks end of stream. Not
        JSON; the payload is the string `[DONE]`.
      contentType: text/plain
      description: |
        Clients must stop reading the stream when this sentinel is observed.
      payload:
        $ref: '#/components/schemas/StreamDoneSentinel'
      examples:
        - name: done
          summary: End-of-stream sentinel
          payload: '[DONE]'
  schemas:
    StreamDoneSentinel:
      type: string
      enum:
        - '[DONE]'
      description: |
        End-of-stream sentinel. The full SSE line is `data: [DONE]`. The
        payload value modeled here is the string literal `[DONE]`.
    ChatCompletionChunk:
      type: object
      description: |
        Represents a streamed chunk of a chat completion response, in the
        OpenAI-compatible `chat.completion.chunk` shape.
      required:
        - choices
        - created
        - id
        - model
        - object
      properties:
        id:
          type: string
          description: A unique identifier for the chat completion. Each chunk has the same ID.
        choices:
          type: array
          description: |
            A list of chat completion choices. Can contain more than one element
            if `n` is greater than 1.
          items:
            $ref: '#/components/schemas/ChatCompletionChunkChoice'
        created:
          type: integer
          description: Unix timestamp (seconds) of when the chat completion was created. Each chunk has the same timestamp.
        model:
          type: string
          description: The model used to generate the completion.
        object:
          type: string
          enum:
            - chat.completion.chunk
          description: The object type, which is always `chat.completion.chunk`.
        usage:
          $ref: '#/components/schemas/CompletionUsage'
    ChatCompletionChunkChoice:
      type: object
      required:
        - delta
        - finish_reason
        - index
      properties:
        index:
          type: integer
          description: The index of the choice in the list of choices.
        delta:
          $ref: '#/components/schemas/ChatCompletionStreamResponseDelta'
        logprobs:
          type: object
          nullable: true
          description: Log probability information for the choice, if requested.
        finish_reason:
          type: string
          nullable: true
          enum:
            - stop
            - length
            - tool_calls
          description: |
            Reason the model stopped generating tokens. `stop` for natural stop
            or a provided stop sequence; `length` if `max_tokens` was reached;
            `tool_calls` if the model called a tool. Null on all chunks except
            the final content chunk.
    ChatCompletionStreamResponseDelta:
      type: object
      description: A chat completion delta generated by streamed model responses.
      properties:
        role:
          type: string
          enum:
            - system
            - user
            - assistant
            - tool
          description: |
            Role of the author of this message. Typically only emitted on the
            first chunk of a choice.
        content:
          type: string
          nullable: true
          description: The contents of the chunk message (token slice).
        tool_calls:
          type: array
          description: |
            Streaming tool-call fragments. Each item carries a delta of a single
            tool call indexed by `index`.
          items:
            type: object
            properties:
              index:
                type: integer
              id:
                type: string
              type:
                type: string
                enum:
                  - function
              function:
                type: object
                properties:
                  name:
                    type: string
                  arguments:
                    type: string
            required:
              - index
    CompletionUsage:
      type: object
      nullable: true
      description: |
        Usage statistics for the completion request. Sent on the final chunk
        when usage reporting is enabled. Null on intermediate chunks.
      required:
        - prompt_tokens
        - completion_tokens
        - total_tokens
      properties:
        prompt_tokens:
          type: integer
          description: Number of tokens in the prompt.
        completion_tokens:
          type: integer
          description: Number of tokens in the generated completion.
        total_tokens:
          type: integer
          description: Total tokens used in the request (prompt + completion).