OpenAI

First, install the OpenAI adapter package:

npm install @hashbrownai/openai

Streaming Text Responses

Hashbrown’s OpenAI adapter lets you stream chat completions from OpenAI’s GPT models, including support for function calling, response schemas, and request transforms.

API Reference

HashbrownOpenAI.stream.text(options)

Streams an OpenAI chat completion as a series of encoded frames. Handles content, tool calls, and errors, and yields each frame as a Uint8Array.

Options:

Name	Type	Description
apiKey	string	Your OpenAI API Key.
request	Chat.Api.CompletionCreateParams	The chat request: model, messages, tools, system, responseFormat, etc.
transformRequestOptions	(params) => params | Promise	(Optional) Transform or override the final OpenAI request before it is sent.

Supported Features:

• Roles: user, assistant, tool
• Tools: Supports OpenAI function calling, including toolCalls and strict function schemas.
• Response Format: Optionally specify a JSON schema for structured output (uses OpenAI’s response_format parameter).
• System Prompt: Included as the first message if provided.
• Function Calling: Handles OpenAI function calling modes and emits tool call frames.
• Streaming: Each chunk is encoded into a resilient streaming format

How It Works

• Messages: Translated to OpenAI’s message format, supporting all roles and tool calls.
• Tools/Functions: Tools are passed as OpenAI function definitions, using your JSON schemas as parameters.
• Response Format: Pass a JSON schema in responseFormat for OpenAI to validate the model output.
• Streaming: All data is sent as a stream of encoded frames (Uint8Array). Chunks may contain text, tool calls, errors, or finish signals.
• Error Handling: Any thrown errors are sent as error frames before the stream ends.

Example: Using with Express

import { HashbrownOpenAI } from '@hashbrownai/openai';

app.post('/chat', async (req, res) => {
  const stream = HashbrownOpenAI.stream.text({
    apiKey: process.env.OPENAI_API_KEY!,
    request: req.body, // must be Chat.Api.CompletionCreateParams
  });

  res.header('Content-Type', 'application/octet-stream');

  for await (const chunk of stream) {
    res.write(chunk); // Pipe each encoded frame as it arrives
  }

  res.end();
});

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Advanced: Tools, Function Calling, and Response Schema

• Tools: Add tools using OpenAI-style function specs (name, description, parameters).
• Function Calling: Supported via toolChoice (auto, required, none, etc.).
• Response Format: Pass a JSON schema in responseFormat for OpenAI to return validated structured output.