v6.45.0 can't handle stream keepalive events

[katemarkson]

Confirm this is a Node library issue and not an underlying OpenAI API issue

• This is an issue with the Node library

Describe the bug

On a long-running request, I see:

Unhandled response stream event: {"type":"keepalive","sequence_number":466}

I don't think OpenAI ever documented keepalive events but they definitely exist.

To Reproduce

1. Send a request that will take a long time to the Responses API, such as using gpt-5.5-pro on xhigh or something. Must be a streaming request. Disable reasoning summaries to increase chance of repro.
2. Wait
3. SDK emits an error as soon as a keepalive event is emitted because there's no case for it.

openai-node/src/lib/responses/ResponseAccumulator.ts

Lines 410 to 412 in 71d2347

	function assertNever(value: never): never {
	throw new OpenAIError(`Unhandled response stream event: ${JSON.stringify(value)}`);
	}

Code snippets

OS

Windows

Node version

Node v24.14.0

Library version

openai v6.45.0