Claude Code SDK Ruby

Official Ruby SDK for interacting with Claude Code CLI. This gem provides a Ruby-idiomatic interface to Claude Code with full async support, proper error handling, and comprehensive type definitions.

Installation

Add this line to your application's Gemfile:

gem 'claude-code-sdk-ruby'

And then execute:

bundle install

Or install it yourself as:

gem install claude-code-sdk-ruby

Prerequisites

This SDK requires the Claude Code CLI to be installed:

npm install -g @anthropic-ai/claude-code

You'll also need to configure your API key. Please refer to the Claude Code documentation for detailed setup instructions.

Quick Start

require 'claude_sdk'

# Simple query
ClaudeSDK.query("What is 2+2?") do |message|
  case message
  when ClaudeSDK::Messages::Assistant
    message.content.each do |block|
      puts block.text if block.is_a?(ClaudeSDK::ContentBlock::Text)
    end
  when ClaudeSDK::Messages::Result
    puts "Session completed in #{message.duration_ms}ms"
  end
end

Usage

Basic Query

require 'claude_sdk'

ClaudeSDK.query("Hello, Claude!") do |message|
  puts message
end

With Options

require 'claude_sdk'

options = ClaudeSDK::ClaudeCodeOptions.new(
  allowed_tools: ['Read', 'Write', 'Bash'],
  max_turns: 3,
  system_prompt: 'You are a helpful coding assistant.',
  cwd: '/path/to/working/directory'
)

ClaudeSDK.query("Help me write a Ruby script", options: options) do |message|
  case message
  when ClaudeSDK::Messages::Assistant
    message.content.each do |block|
      case block
      when ClaudeSDK::ContentBlock::Text
        puts block.text
      when ClaudeSDK::ContentBlock::ToolUse
        puts "Tool: #{block.name}"
        puts "Input: #{block.input}"
      end
    end
  when ClaudeSDK::Messages::Result
    puts "Completed in #{message.num_turns} turns"
    puts "Total cost: $#{message.total_cost_usd}"
  end
end

Without Block (Returns Enumerator)

require 'claude_sdk'

messages = ClaudeSDK.query("Hello")
messages.each do |message|
  puts message
end

Advanced: Using the Internal Client Directly

require 'claude_sdk/internal/client'

client = ClaudeSDK::Internal::InternalClient.new
options = ClaudeSDK::ClaudeCodeOptions.new(
  allowed_tools: ['Read', 'Bash'],
  max_turns: 5
)

Async do
  client.process_query(prompt: "What files are in this directory?", options: options) do |message|
    case message
    when ClaudeSDK::Messages::Assistant
      puts "Assistant response received"
    when ClaudeSDK::Messages::System
      puts "System message: #{message.subtype}"
    when ClaudeSDK::Messages::Result
      puts "Query completed"
    end
  end
end

Message Types

The SDK provides several message types:

• ClaudeSDK::Messages::User - User input messages
• ClaudeSDK::Messages::Assistant - Assistant responses containing content blocks
• ClaudeSDK::Messages::System - System messages (tool results, errors)
• ClaudeSDK::Messages::Result - Query completion results with timing and cost info
• ClaudeSDK::Messages::Error - Error messages from the CLI

Content Blocks

Assistant messages contain content blocks:

• ClaudeSDK::ContentBlock::Text - Text content
• ClaudeSDK::ContentBlock::ToolUse - Tool usage
• ClaudeSDK::ContentBlock::ToolResult - Tool results

Configuration Options

The ClaudeCodeOptions class supports all Claude Code CLI options:

• allowed_tools - Array of allowed tool names (e.g., ['Read', 'Write', 'Bash'])
• disallowed_tools - Array of disallowed tool names
• max_turns - Maximum conversation turns
• system_prompt - System prompt for the conversation
• append_system_prompt - Additional system prompt to append
• cwd - Working directory for file operations
• model - Model to use (e.g., 'claude-3-opus')
• permission_mode - Permission mode (:default, :accept_edits, :auto, :ask)
• permission_prompt_tool_name - Tool for permission prompts
• continue_conversation - Whether to continue from previous conversation
• resume - Resume from a specific conversation ID
• mcp_servers - MCP server configuration

Error Handling

The SDK provides specific error types:

begin
  ClaudeSDK.query("Hello") do |message|
    puts message
  end
rescue ClaudeSDK::CLINotFoundError => e
  puts "Claude Code CLI not found: #{e.message}"
rescue ClaudeSDK::CLIConnectionError => e
  puts "Connection error: #{e.message}"
rescue ClaudeSDK::ProcessError => e
  puts "Process error: #{e.message}"
end

Requirements

• Ruby 3.0 or higher
• Node.js (for Claude Code CLI)
• async gem for async support

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

# Run tests
bundle exec rspec

# Run tests with coverage
COVERAGE=true bundle exec rspec

# Build the gem
gem build claude-code-sdk-ruby.gemspec

# Install locally
gem install ./claude-code-sdk-ruby-0.1.0.gem

To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/parruda/claude-code-sdk-ruby.

License

The gem is available as open source under the terms of the MIT License.