inject-user-id

An OpenCode plugin that injects metadata.user_id into configured model request bodies (/v1/messages and /v1/chat/completions).

A relay that routes by metadata.user_id can then pin all of a session's requests to one upstream account, keeping the prompt-cache hit rate high — so you get the caching benefit without running a separate request-rewriting proxy in front of OpenCode.

It wraps globalThis.fetch inside the plugin server() hook (the same mechanism @lucentia/opencode-trace uses), so it composes with other plugins.

Install

Add it to the plugin array in ~/.config/opencode/opencode.json:

{
  "plugin": ["inject-user-id"],
  "provider": {
    "claudecode": {
      "npm": "@ai-sdk/anthropic",
      "options": {
        "baseURL": "https://api.claudecode.net.cn/api/claudecode/v1",
        "apiKey": "{env:LLM_API_KEY}"
      },
      "models": { "claude-opus-4-8": {} }
    }
  }
}

OpenCode fetches and caches the plugin from npm. Because the metadata is added in-process, the provider baseURL points straight at the remote relay — no local proxy needed.

Configure

export INJECT_HOST=api.claudecode.net.cn
export INJECT_ID=your-stable-user-or-session-id

INJECT_HOST is required for injection. It is a comma-separated list. Each entry can be either:

• a bare host, matching that host and its subdomains: api.claudecode.net.cn,relay.example.com
• a full URL prefix: https://api.claudecode.net.cn/api/claudecode/v1

INJECT_ID is optional. If unset, the plugin falls back to the built-in stable id stable-user-or-session-id-xxxxxxx123.

Behaviour

Injection happens only when all of these hold. Otherwise the request is passed through untouched.

• the request URL matches one of the INJECT_HOST entries;
• the request is a POST to …/messages or …/chat/completions;
• the request body is JSON;
• an existing metadata object is merged, not overwritten;
• all other request fields are preserved.

Run the tests: npm test.

License

MIT