Braintrust Streaming (SSE) API

asyncapi: 2.6.0
info:
  title: Braintrust Streaming (SSE) API
  version: '1.0'
  description: >-
    AsyncAPI description of Braintrust's documented HTTP Server-Sent Events
    (SSE) streams. Braintrust does NOT expose a WebSocket API. Streaming is
    delivered as one-way HTTP SSE over the same REST endpoints when the
    request body sets `stream: true`: streaming function invocation and the
    OpenAI-compatible AI proxy chat completions endpoint. This document models
    those SSE streams; it must not be read as describing a WebSocket transport.
  x-transport-notes: >-
    Transport is HTTP/1.1 (or HTTP/2) with Content-Type text/event-stream.
    The client opens a normal HTTPS POST request with `stream: true`; the
    server holds the response open and emits `data:` SSE events until a final
    `data: [DONE]` sentinel (proxy) or stream completion (invoke). This is a
    unidirectional server-to-client stream, not a bidirectional WebSocket.
  contact:
    name: Braintrust Support
    url: https://www.braintrust.dev/docs
    email: support@braintrust.dev
servers:
  production:
    url: api.braintrust.dev
    protocol: https
    description: >-
      Braintrust US data plane. SSE streams are delivered over HTTPS POST
      requests with stream=true; this is HTTP Server-Sent Events, not
      WebSocket. EU data plane is api-eu.braintrust.dev.
    security:
      - bearerAuth: []
defaultContentType: text/event-stream
channels:
  /v1/proxy/chat/completions:
    description: >-
      OpenAI-compatible chat completions over the AI proxy. When the request
      sets stream=true, the response is an SSE stream of completion chunks
      terminated by a `data: [DONE]` event.
    bindings:
      http:
        type: request
        method: POST
        bindingVersion: '0.1.0'
    subscribe:
      operationId: streamProxyChatCompletions
      summary: Receive streamed chat completion chunks over SSE.
      bindings:
        http:
          bindingVersion: '0.1.0'
      message:
        $ref: '#/components/messages/ChatCompletionChunk'
  /v1/function/{function_id}/invoke:
    description: >-
      Server-side function invocation. When the request sets stream=true, the
      function result is delivered as an SSE stream of progress and result
      events.
    parameters:
      function_id:
        description: The unique identifier of the function being invoked.
        schema:
          type: string
          format: uuid
    bindings:
      http:
        type: request
        method: POST
        bindingVersion: '0.1.0'
    subscribe:
      operationId: streamFunctionInvoke
      summary: Receive streamed function invocation events over SSE.
      bindings:
        http:
          bindingVersion: '0.1.0'
      message:
        $ref: '#/components/messages/FunctionInvokeEvent'
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: API key or JWT
      description: Authorization Bearer header carrying a Braintrust API key.
  messages:
    ChatCompletionChunk:
      name: chatCompletionChunk
      title: Chat Completion Chunk (SSE data event)
      contentType: text/event-stream
      summary: One SSE `data:` event carrying a partial chat completion delta.
      payload:
        type: object
        properties:
          id:
            type: string
          object:
            type: string
            example: 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
                finish_reason:
                  type: string
                  nullable: true
    FunctionInvokeEvent:
      name: functionInvokeEvent
      title: Function Invoke Event (SSE data event)
      contentType: text/event-stream
      summary: One SSE `data:` event carrying a chunk of the function invocation result.
      payload:
        type: object
        properties:
          type:
            type: string
            description: The event type, e.g. progress, console, or text/json result chunk.
          data:
            description: The event payload; shape depends on the function and event type.