Cursor → ACP Adapter

An adapter that bridges the Cursor CLI agent (cursor-agent) to the Agent Client Protocol (ACP). It exposes the Cursor agent over ACP’s ndjson stream so any ACP client can drive it. So far, it can be used in these clients:
- Zed
- JetBrains (coming soon)
- AionUi
- Emacs via agent-shell.el
- marimo notebook
- neovim
- through the CodeCompanion plugin
- through the yetone/avante.nvim plugin

Features

- Prompt streaming: forwards assistant/user chunks from Cursor to ACP in real time
- Tool call mapping:
- Search: grepToolCall/globToolCall → ACP tool_call with summaries and file locations
- Execute: bashToolCall/shellToolCall → ACP tool_call with output + exit code
- Read/Write: map to content blocks and diffs
- Modes: default and plan mode, including current_mode_update
- Cancellation: keeps streaming updates, responds with cancelled, and flushes final updates before resolve
- Auth hint: if the Cursor CLI requires auth, emits a helpful login message

Install

- Node.js 18+
- Cursor CLI (cursor-agent) installed and on PATH

Then:

``bash
npm install
npm run build
`

Usage

Expose the ACP server:

`bash
node ./dist/index.js
`

By default, the adapter calls cursor-agent on your PATH. To use a specific binary:

`bash
export CURSOR_AGENT_EXECUTABLE=/full/path/to/cursor-agent
`

Authenticate Cursor if needed:

`bash
cursor-agent login
`

Integration (ACP Client)

Point your ACP client to the adapter’s stdio process. For SDK-based clients, use ndJsonStream with the adapter’s stdin/stdout.

$3

`js
import { spawn } from "node:child_process";
import { Readable, Writable } from "node:stream";
import { ndJsonStream, ClientSideConnection, PROTOCOL_VERSION } from "@agentclientprotocol/sdk";

const env = { ...process.env };
// Optional: target a specific Cursor binary
// env.CURSOR_AGENT_EXECUTABLE = "/usr/local/bin/cursor-agent";

// Start the adapter
const proc = spawn("node", ["./dist/index.js"], { stdio: ["pipe", "pipe", "inherit"], env });

// Wire ACP stream
const input = Writable.toWeb(proc.stdin);
const output = Readable.toWeb(proc.stdout);
const stream = ndJsonStream(input, output);

// Minimal client
class Client { async requestPermission({ options }) { return { outcome: { outcome: "selected", optionId: options?.[0]?.optionId ?? "allow-once" } }; }
async sessionUpdate(u) { if (u.update.sessionUpdate === "agent_message_chunk" && u.update.content.type === "text") console.log(u.update.content.text); } }

const conn = new ClientSideConnection(() => new Client(), stream);

// Drive a simple prompt
const init = await conn.initialize({ protocolVersion: PROTOCOL_VERSION, clientCapabilities: { fs: { readTextFile: true, writeTextFile: true } } });
const { sessionId } = await conn.newSession({ cwd: process.cwd(), mcpServers: [] });
const res = await conn.prompt({ sessionId, prompt: [{ type: "text", text: "Say hello" }] });
console.log("stopReason=", res.stopReason);
proc.kill();
`

Zed

Use this adapter as an External Agent in Zed.

1) Build the adapter

`bash
cd /path/to/cursor-acp/cursor-acp
npm install
npm run build
`

2) Configure Zed (settings.json)

Add an entry under agent_servers pointing to the built adapter:

`jsonc
"agent_servers": {
// ... your other agents
"Cursor": {
"command": "node",
"args": ["/absolute/path/to/cursor-acp/cursor-acp/dist/index.js"],
"env": {
// Optional: only if cursor-agent isn’t on PATH
// "CURSOR_AGENT_EXECUTABLE": "/usr/local/bin/cursor-agent"
}
}
}
`

3) Use it in Zed

- Open the Agent panel in Zed.
- Click "+" → New Thread → choose "Cursor".
- If prompted to authenticate, run cursor-agent login in a terminal and retry.

Environment

- CURSOR_AGENT_EXECUTABLE – optional path to the Cursor binary (defaults to cursor-agent)

Notes

- The adapter forwards tool call updates even after cancellation, then responds with cancelled as required by ACP.
- For shell tools, empty stdout is rendered as “(no output)” and exit code is included when provided.

Development

- Build: npm run build
- Watch: npm run dev`

License

MIT