Claude Code SDK for Ruby

gem 'claude_code_sdk'

require 'claude_code_sdk'

# Simple question
response = ClaudeCodeSDK.ask("What's the best way to implement a singleton in Ruby?")
puts response

# Code generation with streaming
ClaudeCodeSDK.query("Create a Ruby class for managing a todo list") do |message|
  if message.is_a?(ClaudeCodeSDK::AssistantMessage)
    message.content.each do |block|
      print block.text if block.is_a?(ClaudeCodeSDK::Content::TextBlock)
    end
  end
end

# Generate code with specific requirements
ClaudeCodeSDK.query(
  "Create a thread-safe cache implementation with TTL support",
  system_prompt: "You are an expert Ruby developer focused on performance and thread safety"
) do |message|
  # Handle streaming responses
end

# Refactor existing code
code = File.read("legacy_code.rb")
ClaudeCodeSDK.ask("Refactor this code to use modern Ruby patterns:\n\n#{code}")

# Allow Claude to read and modify files
ClaudeCodeSDK.query(
  "Update all test files to use RSpec 3 syntax",
  allowed_tools: ["read_file", "write_file", "list_files"],
  cwd: Rails.root.to_s
) do |message|
  # Claude will analyze and update your test files
end

# Analyze code for potential issues
ClaudeCodeSDK.query(
  "Analyze this Rails controller for security vulnerabilities and performance issues",
  allowed_tools: ["read_file"],
  tree: ["app/controllers"],
  tree_verbose: true
) do |message|
  # Get detailed analysis with file context
end

# Build features interactively
options = ClaudeCodeSDK::Options.new(
  allowed_tools: ["read_file", "write_file", "bash"],
  permission_mode: ClaudeCodeSDK::PermissionMode::ACCEPT_EDITS,
  max_thinking_tokens: 20000
)

ClaudeCodeSDK.query("Help me add user authentication to my Sinatra app", options) do |message|
  case message
  when ClaudeCodeSDK::AssistantMessage
    # Claude's responses and actions
  when ClaudeCodeSDK::SystemMessage
    puts "[System] #{message.title}: #{message.message}"
  when ClaudeCodeSDK::ResultMessage
    puts "Task completed! Cost: $#{message.cost[:usd]}"
  end
end

ClaudeCodeSDK.configure do |config|
  config.default_system_prompt = "You are a Ruby on Rails expert"
  config.default_cwd = Rails.root.to_s
  config.default_permission_mode = ClaudeCodeSDK::PermissionMode::DEFAULT
  config.default_allowed_tools = ["read_file", "list_files"]
end

ClaudeCodeSDK.query("Build a REST API endpoint") do |message|
  case message
  when ClaudeCodeSDK::UserMessage
    # Your input to Claude
    
  when ClaudeCodeSDK::AssistantMessage
    message.content.each do |block|
      case block
      when ClaudeCodeSDK::Content::TextBlock
        # Claude's text responses
        puts block.text
        
      when ClaudeCodeSDK::Content::ToolUseBlock
        # Claude using a tool
        puts "Using tool: #{block.name}"
        
      when ClaudeCodeSDK::Content::ToolResultBlock
        # Results from tool execution
        puts "Tool output: #{block.output}"
      end
    end
    
  when ClaudeCodeSDK::SystemMessage
    # System notifications
    
  when ClaudeCodeSDK::ResultMessage
    # Final results with usage stats
    puts "Tokens used: #{message.usage[:total_tokens]}"
  end
end

begin
  ClaudeCodeSDK.query("Complex task") do |message|
    # Handle messages
  end
rescue ClaudeCodeSDK::CLINotFoundError => e
  # Claude Code CLI not installed
rescue ClaudeCodeSDK::ProcessError => e
  # Process execution failed
  puts "Exit code: #{e.exit_code}"
  puts "Error: #{e.stderr}"
rescue ClaudeCodeSDK::TimeoutError => e
  # Operation timed out
rescue ClaudeCodeSDK::CLIJSONDecodeError => e
  # Invalid response from CLI
end

# Help with Rails development tasks
ClaudeCodeSDK.query(
  "Add a full-text search feature to the Product model using PostgreSQL",
  allowed_tools: ["read_file", "write_file", "bash"],
  cwd: Rails.root.to_s,
  system_prompt: "You are a Rails expert. Follow Rails conventions and best practices."
) do |message|
  # Claude will analyze your models, create migrations, and implement search
end

# Generate comprehensive tests
ClaudeCodeSDK.query(
  "Generate RSpec tests for the UserService class with full coverage",
  allowed_tools: ["read_file", "write_file"],
  tree: ["app/services", "spec"]
) do |message|
  # Claude analyzes your code and creates thorough test suites
end

# Automated code review
changed_files = `git diff --name-only main`.split("\n")
ClaudeCodeSDK.query(
  "Review these changed files for code quality, potential bugs, and improvements",
  allowed_tools: ["read_file"],
  tree: changed_files
) do |message|
  # Get detailed code review feedback
end