cursor-oauth-opencode

cursor-oauth-opencode

OpenCode plugin that connects to Cursor's API, giving you access to Cursor models inside OpenCode with full tool-calling support.

Install

npx cursor-oauth-opencode setup --global
opencode auth login --provider cursor

For project-local setup:

npx cursor-oauth-opencode setup --project
opencode auth login --provider cursor

The setup command is idempotent. It adds the npm plugin entry and a fallback provider.cursor model registry to opencode.json, preserving existing user model overrides.

Manual config

If you do not want to use the setup command, add this to ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": [
    "cursor-oauth-opencode@latest"
  ],
  "provider": {
    "cursor": {
      "name": "Cursor",
      "npm": "@ai-sdk/openai-compatible",
      "api": "http://127.0.0.1:65535/v1",
      "models": {
        "composer-2-fast": {
          "name": "Composer 2 Fast",
          "reasoning": true,
          "temperature": true,
          "attachment": false,
          "tool_call": true,
          "limit": {
            "context": 200000,
            "output": 64000
          }
        }
      }
    }
  }
}

The fallback API URL is only a placeholder so OpenCode can list the provider before login. After auth, the plugin starts a local proxy and replaces Cursor models with live Cursor model discovery.

Authenticate

opencode auth login --provider cursor

This opens Cursor OAuth in the browser. Tokens are stored in ~/.local/share/opencode/auth.json and refreshed automatically.

Use

Start OpenCode and select any Cursor model. The plugin starts a local OpenAI-compatible proxy on demand and routes requests through Cursor's gRPC API.

How it works

• OAuth — browser-based login to Cursor via PKCE.
• Model discovery — queries Cursor's gRPC API for all available models.
• Local proxy — translates POST /v1/chat/completions into Cursor's protobuf/HTTP/2 Connect protocol.
• Native tool routing — rejects Cursor's built-in filesystem/shell tools and exposes OpenCode's tool surface via Cursor MCP instead.

HTTP/2 transport runs through a Node child process (h2-bridge.mjs) because Bun's node:http2 support is not reliable against Cursor's API.

Architecture

OpenCode  -->  /v1/chat/completions  -->  Bun.serve (proxy)
                                              |
                                    Node child process (h2-bridge.mjs)
                                              |
                                     HTTP/2 Connect stream
                                              |
                                    api2.cursor.sh gRPC
                                      /agent.v1.AgentService/Run

Tool call flow

1. Cursor model receives OpenAI tools via RequestContext (as MCP tool defs)
2. Model tries native tools (readArgs, shellArgs, etc.)
3. Proxy rejects each with typed error (ReadRejected, ShellRejected, etc.)
4. Model falls back to MCP tool -> mcpArgs exec message
5. Proxy emits OpenAI tool_calls SSE chunk, pauses H2 stream
6. OpenCode executes tool, sends result in follow-up request
7. Proxy resumes H2 stream with mcpResult, streams continuation

Develop locally

bun install
bun run build
bun test/smoke.ts

Requirements

• OpenCode
• Bun
• Node.js >= 18 for the HTTP/2 bridge process
• Active Cursor subscription