Cursor Agent ACP Adapter

A full-featured Agent Client Protocol (ACP) adapter for Cursor CLI, enabling seamless AI-powered coding assistance in ACP-compliant editors like Zed.

Overview

This TypeScript implementation provides a production-ready bridge between the Cursor CLI and editors that support the Agent Client Protocol. Built on the standard stdio transport per ACP specification, it offers feature parity with Zed's built-in Claude and Codex adapters while maintaining high performance and reliability.

Features

• ACP Protocol Core - Initialize, session management, prompt processing
• Strict Schema Compliance - 100% adherence to ACP Schema
• Stdio Transport - Standard ACP stdio transport per protocol specification
• Session Management - Persistent sessions with metadata and history
• Content Processing - Text, code, and image block handling per ContentBlock schema
• Real-time Streaming - Live response streaming for immediate feedback
• Complete Tool System - Filesystem, terminal, and Cursor-specific tools
• Security Framework - Path validation, command filtering, access controls
• Error Handling & Recovery - Robust error handling with comprehensive validation
• Type Safety - Written in TypeScript with strict type checking using @agentclientprotocol/sdk
• SDK Integration - All protocol types imported from official @agentclientprotocol/sdk
• Test Coverage - 200+ unit and integration tests with security coverage
• Cursor CLI Integration - Complete integration with cursor-agent CLI features
• Advanced Tool Registry - Dynamic provider management and validation
• Cross-Tool Workflows - Seamless filesystem, terminal, and code operations
• High Performance - <100ms average response time optimization
• Memory Efficiency - Zero memory leaks, optimal resource usage
• Cross-platform - Works on macOS, Linux, and Windows

ACP Schema Compliance

This adapter strictly adheres to the Agent Client Protocol Schema. Key compliance features:

Protocol Types

• All types imported from @agentclientprotocol/sdk - No custom protocol type definitions
• PromptRequest - Uses prompt field per schema (ContentBlock[])
• SessionUpdate - Full union type support (user_message_chunk, agent_message_chunk, agent_thought_chunk, tool_call, tool_call_update, plan, available_commands_update, current_mode_update)
• ContentBlock - Complete support for text, image, audio, resource, resource_link
• SessionCapabilities - Properly declared in AgentCapabilities
• Terminal types - Full Terminal, TerminalHandle, TerminalExitStatus support

Validation

• Content block validation - Strict validation against ContentBlock schema
• Annotations support - Full Annotations type support with _meta extensions
• Error responses - JSON-RPC 2.0 compliant error structures
• Type guards - Runtime validation using SDK type structures

Documentation

• TSDoc comments - All protocol methods link to ACP schema documentation
• Schema references - Direct links to relevant schema sections
• Internal vs Protocol types - Clear separation and documentation

Installation

Prerequisites

1. Node.js 18+ - Required for running the adapter
2. Cursor CLI - Must be installed and authenticated

# Install Cursor CLI
curl https://cursor.com/install -fsSL | bash

# Authenticate with your Cursor account
cursor-agent login

Install the Adapter

# Install globally
npm install -g @blowmage/cursor-agent-acp

# Or install locally in your project
npm install @blowmage/cursor-agent-acp

Usage

Basic Usage

# Start the ACP adapter with stdio transport
cursor-agent-acp

# Or run directly with npx
npx cursor-agent-acp

The adapter uses stdio transport by default, which is the standard transport for the Agent Client Protocol. The adapter reads JSON-RPC messages from stdin and writes responses to stdout, with messages delimited by newlines as specified in the ACP Transport Specification.

Zed Editor Integration

Add this configuration to your Zed settings (~/.config/zed/settings.json):

{
  "agent_servers": {
    "cursor-agent": {
      "command": "cursor-agent-acp",
      "args": [],
      "env": {}
    }
  }
}

If installed locally:

{
  "agent_servers": {
    "cursor-agent": {
      "command": "npx",
      "args": ["@blowmage/cursor-agent-acp"],
      "env": {}
    }
  }
}

JetBrains IDE Integration

The adapter supports JetBrains IDEs (WebStorm, IntelliJ IDEA, PyCharm, etc.) version 25.3 and later.

Create or edit ~/.jetbrains/acp.json:

{
  "agent_servers": {
    "Cursor Agent": {
      "command": "cursor-agent-acp",
      "args": [],
      "env": {}
    }
  }
}

Or configure through the IDE:

1. Open AI Chat tool window
2. Click ⚙️ settings → "Configure ACP Agents"
3. Add the configuration above

Using with Other Editors

The adapter works with any ACP-compliant editor using the standard stdio transport. Configure your editor to launch cursor-agent-acp as an agent server process.

Transport Layer

This adapter implements the stdio transport as specified in the ACP Transport Specification.

Stdio Transport (Default)

The stdio transport is the recommended transport for ACP:

• Standard Communication: JSON-RPC messages over stdin/stdout
• Message Format: Newline-delimited JSON (\n delimiter)
• Logging: Uses stderr for diagnostic output
• No Embedded Newlines: Messages must not contain \n or \r
• SDK Compliant: Uses @agentclientprotocol/sdk for all protocol handling

Why Stdio?

Stdio is the default and recommended transport for ACP because:

1. Universal Support: Works with any process-based editor integration
2. Simple & Reliable: Well-understood subprocess communication
3. Specification Compliant: Follows ACP transport specification exactly
4. SDK Integration: Full support via @agentclientprotocol/sdk

Configuration

The adapter supports various configuration options:

# Custom configuration file
cursor-agent-acp --config /path/to/config.json

# Set log level
cursor-agent-acp --log-level debug

# Specify session storage directory
cursor-agent-acp --session-dir ~/.cursor-sessions

Configuration File Example

{
  "logLevel": "info",
  "sessionDir": "~/.cursor-sessions",
  "maxSessions": 100,
  "sessionTimeout": 3600000,
  "tools": {
    "filesystem": {
      "enabled": true,
      "allowedPaths": ["./"],
      "maxFileSize": 10485760,
      "allowedExtensions": [".ts", ".js", ".json", ".md"]
    },
    "terminal": {
      "enabled": true,
      "maxProcesses": 5,
      "defaultOutputByteLimit": 10485760,
      "maxOutputByteLimit": 52428800,
      "forbiddenCommands": ["rm", "sudo", "su"],
      "allowedCommands": [],
      "defaultCwd": "./"
    },
    "cursor": {
      "enabled": true,
      "enableCodeModification": true,
      "enableTestExecution": true,
      "maxSearchResults": 50
    }
  },
  "cursor": {
    "timeout": 30000,
    "retries": 3
  }
}

Development

Setup

# Clone the repository
git clone https://github.com/blowmage/cursor-agent-acp.git
cd cursor-agent-acp

# Install dependencies
npm install

# Build the project
npm run build

Testing

# Run unit tests
npm test

# Run integration tests
npm run test:integration

# Run all tests with coverage
npm run test:coverage

# Watch mode for development
npm run test:watch

Development Server

# Run in development mode with hot reload
npm run dev

# Build and watch for changes
npm run build:watch

Architecture

┌─────────────────────────────────────────────────────┐
│                 ACP Editor (Zed)                    │
└─────────────────┬───────────────────────────────────┘
                  │ JSON-RPC over stdio
┌─────────────────▼───────────────────────────────────┐
│             Cursor Agent ACP Adapter                │
│  ┌─────────────────────────────────────────────────┐│
│  │           Protocol Layer                        ││
│  │  • Initialization  • Session Management         ││
│  │  • Prompt Handling • Content Processing         ││
│  │  • Tool Calling    • Error Handling             ││
│  └─────────────────────────────────────────────────┘│
│  ┌─────────────────────────────────────────────────┐│
│  │           Integration Layer                     ││
│  │  • CLI Bridge     • Authentication              ││
│  │  • Session Sync   • Response Translation        ││
│  └─────────────────────────────────────────────────┘│
└─────────────────┬───────────────────────────────────┘
                  │ Command execution
┌─────────────────▼───────────────────────────────────┐
│                Cursor CLI                           │
└─────────────────────────────────────────────────────┘

API Documentation

Core Classes

• CursorAgentAdapter - Main adapter class implementing ACP protocol
• SessionManager - Handles session lifecycle and persistence
• CursorCliBridge - Interfaces with cursor-agent CLI
• ToolRegistry - Manages available tools and capabilities

Supported ACP Methods

• initialize - Initialize the adapter with capabilities
• session/new - Create a new conversation session
• session/load - Load an existing session
• session/list - List all available sessions
• session/update - Update session metadata
• session/delete - Delete a session
• session/prompt - Send a prompt and receive streaming response

Available Tools

• File System Tools

  • read_file - Read file contents with security validation
  • write_file - Write file contents with path restrictions
  • list_directory - List directory contents recursively
  • create_directory - Create directories with parent support
  • delete_file - Delete files/directories with safety checks
  • get_file_info - Get detailed file/directory information

• Terminal Tools

  • execute_command - Execute shell commands with security filtering
  • start_shell_session - Start interactive shell sessions
  • send_to_shell - Send input to active shell sessions
  • close_shell_session - Close and cleanup shell sessions
  • list_processes - List active processes and sessions

• Cursor-Specific Tools

  • search_codebase - Advanced code search with pattern matching
  • analyze_code - Code structure and quality analysis
  • apply_code_changes - Atomic code modifications with backup
  • run_tests - Execute tests with framework auto-detection
  • get_project_info - Project metadata and dependency information
  • explain_code - AI-powered code explanations and suggestions

Troubleshooting

Common Issues

"cursor-agent not found"

# Install Cursor CLI
curl https://cursor.com/install -fsSL | bash

# Verify installation
cursor-agent --version

"Authentication required"

# Login to Cursor
cursor-agent login

# Check authentication status
cursor-agent status

"Permission denied"

# Make sure the binary is executable
chmod +x ./node_modules/.bin/cursor-agent-acp

"Session not found"

• Sessions are stored locally and may expire
• Check session directory permissions
• Verify session storage configuration

Debug Mode

Enable debug logging to troubleshoot issues:

cursor-agent-acp --log-level debug

Check logs in:

• macOS/Linux: ~/.cursor-agent-acp/logs/
• Windows: %APPDATA%\cursor-agent-acp\logs\

Contributing

We welcome contributions! Please see our Contributing Guidelines for details.

Development Workflow

1. Fork the repository
2. Create a feature branch
3. Write tests for your changes
4. Implement the feature
5. Ensure all tests pass
6. Submit a pull request

Code Standards

• TypeScript: Strict mode enabled
• Testing: >95% test coverage required
• Linting: ESLint + Prettier
• Commits: Conventional commit messages

License

MIT License - see LICENSE file for details.

Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Documentation: Full API Docs

Related Projects

• Agent Client Protocol - Official ACP specification
• Cursor CLI - Official Cursor command-line interface
• Zed Editor - High-performance code editor with ACP support