Keywords AI Chat Completions Streaming (HTTP + SSE)

asyncapi: '2.6.0'
id: 'urn:co:keywordsai:api:chat-completions:sse'
info:
  title: Keywords AI Chat Completions Streaming (HTTP + SSE)
  version: '1.0.0'
  description: |
    AsyncAPI 2.6 description of Keywords AI's **chat completion streaming**
    surface on the OpenAI-compatible gateway.

    Keywords AI does not publish a WebSocket API. The only asynchronous /
    event-style transport documented for chat is **HTTP Server-Sent Events
    (SSE)** delivered over the same REST endpoint
    (`POST /chat/completions`) when the request body sets `stream: true`. SSE
    is a one-way, server-to-client HTTP streaming channel; it is **not**
    WebSocket.

    Tokens are sent as data-only server-sent events as they become available,
    with the stream terminated by a `data: [DONE]` message.

    This AsyncAPI document models only the streamed events emitted by the SSE
    response. The request body itself (model, messages, tools, etc.) is modeled
    in the companion OpenAPI document at `openapi/keywordsai-openapi.yml`.

    Note: the company is rebranding to Respan; the keywordsai.co host and API
    remain active.
  contact:
    name: API Evangelist
    email: kin@apievangelist.com
    url: https://apievangelist.com
  license:
    name: API documentation - Keywords AI Terms of Service
    url: https://www.keywordsai.co/terms-of-service
  x-transport-notes:
    transport: HTTP Server-Sent Events (SSE)
    protocol: https
    direction: server-to-client (one-way)
    mediaType: text/event-stream
    triggeredBy: 'POST https://api.keywordsai.co/api/chat/completions with request body { "stream": true }'
    terminator: 'data: [DONE]'
    notWebSocket: true
    source: https://docs.keywordsai.co/api-endpoints/integration/chat-completions
defaultContentType: text/event-stream
servers:
  keywordsai:
    url: api.keywordsai.co/api
    protocol: https
    description: |
      Keywords AI's 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` 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: 'Keywords AI API key'
      description: |
        Standard Keywords AI bearer token. Set the
        `Authorization: Bearer <KEYWORDSAI_API_KEY>` 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 the literal string `chat.completion.chunk`. The
        shape follows the OpenAI-compatible chat completion chunk schema that
        the Keywords AI gateway proxies.
      payload:
        $ref: '#/components/schemas/ChatCompletionChunk'
      examples:
        - name: openingChunk
          summary: First chunk - establishes role
          payload:
            id: chatcmpl-abc123
            object: chat.completion.chunk
            created: 1781827200
            model: gpt-4o-mini
            choices:
              - index: 0
                delta:
                  role: assistant
                  content: ''
                finish_reason: null
        - name: contentChunk
          summary: Token delta
          payload:
            id: chatcmpl-abc123
            object: chat.completion.chunk
            created: 1781827200
            model: gpt-4o-mini
            choices:
              - index: 0
                delta:
                  content: 'Hello'
                finish_reason: null
        - name: finalChunk
          summary: Final chunk - finish_reason set
          payload:
            id: chatcmpl-abc123
            object: chat.completion.chunk
            created: 1781827200
            model: gpt-4o-mini
            choices:
              - index: 0
                delta: {}
                finish_reason: stop
    StreamDone:
      name: StreamDone
      title: Stream termination sentinel
      summary: |
        The literal SSE event `data: [DONE]` that terminates the stream. It is
        not JSON; it is the raw token `[DONE]`.
      contentType: text/plain
      payload:
        type: string
        const: '[DONE]'
      examples:
        - name: done
          summary: Termination sentinel
          payload: '[DONE]'
  schemas:
    ChatCompletionChunk:
      type: object
      required:
        - id
        - object
        - created
        - model
        - choices
      properties:
        id:
          type: string
        object:
          type: string
          const: chat.completion.chunk
        created:
          type: integer
        model:
          type: string
        choices:
          type: array
          items:
            type: object
            properties:
              index:
                type: integer
              delta:
                type: object
                properties:
                  role:
                    type: string
                  content:
                    type: string
                  tool_calls:
                    type: array
                    items:
                      type: object
              finish_reason:
                type: string
                nullable: true
        usage:
          type: object
          nullable: true
          properties:
            prompt_tokens:
              type: integer
            completion_tokens:
              type: integer
            total_tokens:
              type: integer