Cursor Oauth

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

Install in OpenCode

Add this to ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": [
    "opencode-cursor-oauth"
  ]
}

The plugin registers the cursor provider and its models automatically once you are logged in — no manual provider stub or model list is needed.

OpenCode installs npm plugins automatically at startup, so users do not need to clone this repository.

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

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

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 calls a tool:
   - native tools (readArgs, shellArgs, grepArgs, ...) with an OpenCode
     equivalent are redirected to it (read, bash, grep, glob, webfetch, write)
   - native tools without an equivalent are rejected with a typed error
   - MCP tools arrive as mcpArgs exec messages
3. Proxy emits OpenAI tool_calls SSE chunk, pauses H2 stream
4. OpenCode executes tool, sends result in follow-up request
5. Proxy resumes H2 stream with the typed native result (or mcpResult),
   streams continuation

Conversation state

Conversation history is rebuilt from the OpenAI messages on every request (rootPromptMessagesJson + content-addressed turn blobs), and server checkpoints are persisted to ~/.cache/opencode-cursor/conversations/ so context survives restarts. Set CURSOR_PROXY_DEBUG=1 to log the KV blob handshake and exec traffic when debugging.

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