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OpenAI adapter ​

Translates an OpenAI streaming chat completion into a StreamChunk sequence.

Import ​

typescript
import { fromOpenAI } from "streamkit-ui/adapters/openai";
// or (includes all adapters):
import { fromOpenAI } from "streamkit-ui";

Usage ​

typescript
import OpenAI from "openai";
import { fromOpenAI } from "streamkit-ui/adapters/openai";

const client = new OpenAI();

const stream = await client.chat.completions.create({
  model: "gpt-4o",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello" }],
  stream: true,
});

const source = fromOpenAI({ stream });

for await (const chunk of source) {
  console.log(chunk);
}

The OpenAI SDK's stream object already implements AsyncIterable<ChatCompletionChunk>, so it satisfies the adapter's input type directly.

Translation notes ​

Tool call arguments: accumulate, then parse ​

Each ChatCompletionChunk can carry a delta.tool_calls array. The first chunk for a given tool-call index includes the id and function.name; subsequent chunks carry only partial function.arguments JSON fragments — and a fragment can split a JSON token at an arbitrary byte boundary, so it isn't safely parseable on its own.

The adapter tracks per-index state in a Map, emits tool-call-start as soon as id + name are seen, accumulates argument fragments, and emits tool-call-ready (with the fully parsed args) when finish_reason === "tool_calls" flushes them. If the accumulated JSON is malformed, it emits a tool-result with isError: true rather than throwing.

No explicit "done" event ​

OpenAI signals completion via a chunk whose finish_reason is non-null ("stop", "tool_calls", …). The adapter emits streamkit's done on the first non-null finish_reason.

Only the first choice ​

n > 1 (multiple choices) isn't supported — the adapter processes only choice index 0 per chunk, which covers the overwhelming majority of usage. Multiple simultaneous completions are a different use case, better served by useStreamQueue.

Verified against the installed SDK ​

The chunk shape this adapter reads is typed against the installed openai package's type definitions, not documentation.

MIT License