Missing x-opencode-session header in Node.js fetch calls

Description

I received a notification from the model provider ("OpenCode Go") that some requests are missing the required x-opencode-session header. The affected user agent is Node fetch.

Details from provider
“Some of your requests to OpenCode Go are missing an x-opencode-session header. If we don't have this we cannot properly optimize our service. Starting 09/06 requests missing this header may error.”

Impact
“Starting September 6th, 2026, requests without this header may begin failing, potentially causing errors or degraded service.”

Plugins

No response

OpenCode version

Current version: 2.5.3

Steps to reproduce

1. Use Opencode
2. Wait a few days for the email to arrive
3. Investigate what the email is talking about
4. Submit a report, as the issue appears to be related to an error or omission on the part of a developer on GitHub

Screenshot and/or share link

No response

Operating System

Running as Home Assistant add-on (f5588468_ha_opencode)

Terminal

Unknown

Start by tracing the Node.js fetch call sites that construct requests to model providers and check how request headers are assembled. Confirm which requests need x-opencode-session, then add coverage showing the header is present on those requests and that the affected provider calls no longer omit it.