SDK client times out after exactly 5 minutes on Node.js when using session.prompt() #15555

Description

When using @opencode-ai/sdk on Node.js 22 (not Bun), any session.prompt() call that takes longer than 5 minutes fails with:

HeadersTimeoutError: Headers Timeout Error
at FastTimer.onParserTimeout [as _onTimeout] (node:internal/deps/undici/undici:7529:32)
at Timeout.onTick [as _onTimeout] (node:internal/deps/undici/undici:692:17)

This is undici's default headersTimeout of 300,000ms (5 minutes) on Node.js's built-in fetch().

We're using the SDK to orchestrate multi-step agent workflows (fix, lint, review, commit). Short-running prompts (< 5 min)
succeed. Long-running ones (e.g., lint verification via a subagent) fail at exactly 5 minutes every time.

The SDK already has a workaround in packages/sdk/js/src/v2/client.ts that sets req.timeout = false before calling fetch(). It seems this has no effect...

Steps to reproduce:

1. Use @opencode-ai/sdk on Node.js 22 (not Bun)
2. Call client.session.prompt() with a prompt that triggers agent work lasting > 5 minutes
3. The call fails at exactly 5 minutes with HeadersTimeoutError

OpenCode version: SDK @opencode-ai/sdk v1.1.4

Operating System: Linux (Node.js 22 Alpine container)

Plugins

No response

OpenCode version

No response

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response