Class: ClaudeAgentSDK::SubprocessCLITransport

Inherits:
Transport
  • Object
show all
Defined in:
lib/claude_agent_sdk/subprocess_cli_transport.rb

Overview

Subprocess transport using Claude Code CLI

Constant Summary collapse

DEFAULT_MAX_BUFFER_SIZE =

1MB buffer limit

1024 * 1024
MINIMUM_CLAUDE_CODE_VERSION = 
'2.0.0'

Instance Method Summary collapse

Constructor Details

#initialize(options_or_prompt = nil, options = nil) ⇒ SubprocessCLITransport

Returns a new instance of SubprocessCLITransport.



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 16

def initialize(options_or_prompt = nil, options = nil)
  # Support both new single-arg form and legacy two-arg form
  @options = options.nil? ? options_or_prompt : options
  @cli_path = @options.cli_path || find_cli
  @cwd = @options.cwd
  @process = nil
  @stdin = nil
  @stdout = nil
  @stderr = nil
  @ready = false
  @exit_error = nil
  @max_buffer_size = @options.max_buffer_size || DEFAULT_MAX_BUFFER_SIZE
  @stderr_task = nil
  @recent_stderr = []
  @recent_stderr_mutex = Mutex.new
end

Instance Method Details

#build_command ⇒ Object 



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 68

def build_command
  cmd = [@cli_path, '--output-format', 'stream-json', '--verbose']

  # System prompt handling
  # When nil, pass empty string to ensure predictable behavior without default Claude Code system prompt
  if @options.system_prompt.nil?
    cmd.concat(['--system-prompt', ''])
  elsif @options.system_prompt.is_a?(String)
    cmd.concat(['--system-prompt', @options.system_prompt])
  elsif @options.system_prompt.is_a?(SystemPromptFile)
    cmd.concat(['--system-prompt-file', @options.system_prompt.path])
  elsif @options.system_prompt.is_a?(SystemPromptPreset)
    # Preset activates the default Claude Code system prompt by not passing --system-prompt ""
    # Only --append-system-prompt is passed if append text is provided
    cmd.concat(['--append-system-prompt', @options.system_prompt.append]) if @options.system_prompt.append
  elsif @options.system_prompt.is_a?(Hash)
    prompt_type = @options.system_prompt[:type] || @options.system_prompt['type']
    if prompt_type == 'file'
      prompt_path = @options.system_prompt[:path] || @options.system_prompt['path']
      cmd.concat(['--system-prompt-file', prompt_path]) if prompt_path
    elsif prompt_type == 'preset'
      append = @options.system_prompt[:append] || @options.system_prompt['append']
      # Preset activates the default Claude Code system prompt by not passing --system-prompt ""
      cmd.concat(['--append-system-prompt', append]) if append
    end
  end

  cmd.concat(['--allowedTools', @options.allowed_tools.join(',')]) unless @options.allowed_tools.empty?
  cmd.concat(['--max-turns', @options.max_turns.to_s]) if @options.max_turns
  cmd.concat(['--disallowedTools', @options.disallowed_tools.join(',')]) unless @options.disallowed_tools.empty?
  cmd.concat(['--model', @options.model]) if @options.model
  cmd.concat(['--fallback-model', @options.fallback_model]) if @options.fallback_model
  cmd.concat(['--permission-prompt-tool', @options.permission_prompt_tool_name]) if @options.permission_prompt_tool_name
  cmd.concat(['--permission-mode', @options.permission_mode]) if @options.permission_mode
  cmd << '--continue' if @options.continue_conversation
  cmd.concat(['--resume', @options.resume]) if @options.resume
  cmd.concat(['--session-id', @options.session_id]) if @options.session_id

  # Settings handling with sandbox merge
  build_settings_args(cmd)

  # Budget limit option
  cmd.concat(['--max-budget-usd', @options.max_budget_usd.to_s]) if @options.max_budget_usd

  # Task budget (API-side token budget)
  if @options.task_budget
    total = if @options.task_budget.is_a?(TaskBudget)
              @options.task_budget.total
            else
              @options.task_budget[:total] || @options.task_budget['total']
            end
    cmd.concat(['--task-budget', total.to_s]) if total
  end

  # Thinking configuration (takes precedence over deprecated max_thinking_tokens)
  build_thinking_args(cmd)

  # Effort level — see ClaudeAgentSDK::EFFORT_LEVELS. The set of supported
  # levels is model-dependent; the CLI falls back to the highest supported
  # level at or below the one requested (e.g. `xhigh` → `high` on Opus 4.6).
  cmd.concat(['--effort', @options.effort.to_s]) if @options.effort

  # Betas option for enabling experimental features
  if @options.betas && !@options.betas.empty?
    cmd.concat(['--betas', @options.betas.join(',')])
  end

  # Tools option for base tools selection
  build_tools_args(cmd)

  # Append allowed tools option
  if @options.append_allowed_tools && !@options.append_allowed_tools.empty?
    cmd.concat(['--append-allowed-tools', @options.append_allowed_tools.join(',')])
  end

  # JSON schema for structured output
  build_output_format_args(cmd)

  # Add directories
  @options.add_dirs.each do |dir|
    cmd.concat(['--add-dir', dir.to_s])
  end

  # MCP servers
  build_mcp_servers_args(cmd)

  cmd << '--include-partial-messages' if @options.include_partial_messages
  cmd << '--fork-session' if @options.fork_session
  cmd << '--bare' if @options.bare

  # Note: agents are now sent via the initialize control request (not CLI args)
  # to avoid OS ARG_MAX limits with large agent configurations.

  # Plugins
  build_plugins_args(cmd)

  # Setting sources
  sources_value = @options.setting_sources ? @options.setting_sources.join(',') : ''
  cmd.concat(['--setting-sources', sources_value])

  # Extra args
  @options.extra_args.each do |flag, value|
    if value.nil?
      cmd << "--#{flag}"
    else
      cmd.concat(["--#{flag}", value.to_s])
    end
  end

  # Always use streaming mode for bidirectional control protocol.
  # Prompts and agents are sent via stdin (initialize + user messages),
  # which avoids OS ARG_MAX limits for large prompts and agent configurations.
  cmd.concat(['--input-format', 'stream-json'])

  cmd
end

#check_claude_version ⇒ Object 



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 473

def check_claude_version
  begin
    stdout, stderr, = Open3.capture3(@cli_path.to_s, '-v')
    output = (stdout.to_s + stderr.to_s).strip
    if match = output.match(/([0-9]+\.[0-9]+\.[0-9]+)/)
      version = match[1]
      version_parts = version.split('.').map(&:to_i)
      min_parts = MINIMUM_CLAUDE_CODE_VERSION.split('.').map(&:to_i)

      if version_parts < min_parts
        warning = "Warning: Claude Code version #{version} is unsupported in the Agent SDK. " \
                  "Minimum required version is #{MINIMUM_CLAUDE_CODE_VERSION}. " \
                  "Some features may not work correctly."
        warn warning
      end
    end
  rescue StandardError
    # Ignore version check errors
  end
end

#close ⇒ Object 



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 296

def close
  @ready = false
  return unless @process

  cleanup_errors = []

  # Kill stderr thread
  if @stderr_task&.alive?
    begin
      @stderr_task.kill
      @stderr_task.join(1)
    rescue StandardError => e
      cleanup_errors << "stderr thread: #{e.message}"
    end
  end

  # Close streams
  begin
    @stdin&.close
  rescue IOError
    # Already closed, ignore
  rescue StandardError => e
    cleanup_errors << "stdin: #{e.message}"
  end

  begin
    @stdout&.close
  rescue IOError
    # Already closed, ignore
  rescue StandardError => e
    cleanup_errors << "stdout: #{e.message}"
  end

  begin
    @stderr&.close
  rescue IOError
    # Already closed, ignore
  rescue StandardError => e
    cleanup_errors << "stderr: #{e.message}"
  end

  # Wait for graceful shutdown after stdin EOF, then terminate if needed.
  # The subprocess needs time to flush its session file after receiving
  # EOF on stdin. Without this grace period, SIGTERM can interrupt the
  # write and cause the last assistant message to be lost.
  begin
    if @process.alive?
      # Give the process up to 5 seconds to exit on its own
      Timeout.timeout(5) { @process.value }
    end
  rescue Timeout::Error
    # Graceful shutdown timed out — send SIGTERM
    begin
      Process.kill('TERM', @process.pid)
      Timeout.timeout(2) { @process.value }
    rescue Timeout::Error
      # SIGTERM didn't work — force kill
      begin
        Process.kill('KILL', @process.pid)
        @process.value
      rescue StandardError => e
        cleanup_errors << "force kill: #{e.message}"
      end
    rescue Errno::ESRCH
      # Process already dead
    end
  rescue Errno::ESRCH
    # Process already dead, ignore
  rescue StandardError => e
    cleanup_errors << "process termination: #{e.message}"
  end

  # Log any cleanup errors (non-fatal)
  if cleanup_errors.any?
    warn "Claude SDK: Cleanup warnings: #{cleanup_errors.join(', ')}"
  end

  @process = nil
  @stdout = nil
  @stdin = nil
  @stderr = nil
  @stderr_task = nil
  @exit_error = nil
end

#connect ⇒ Object 



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 185

def connect
  return if @process

  check_claude_version

  cmd = build_command

  # Build environment
  # Convert symbol keys to strings for spawn compatibility
  custom_env = @options.env.transform_keys { |k| k.to_s }
  # Explicitly unset CLAUDECODE to prevent "nested session" detection when the SDK
  # launches Claude Code from within an existing Claude Code terminal.
  # NOTE: Must set to nil (not just omit the key) — Ruby's spawn only overlays
  # the env hash on top of the parent environment; a nil value actively unsets.
  process_env = ENV.to_h.merge('CLAUDECODE' => nil, 'CLAUDE_AGENT_SDK_VERSION' => VERSION).merge(custom_env)
  process_env['CLAUDE_CODE_ENTRYPOINT'] ||= 'sdk-rb'
  process_env['CLAUDE_CODE_ENABLE_SDK_FILE_CHECKPOINTING'] = 'true' if @options.enable_file_checkpointing
  process_env['PWD'] = @cwd.to_s if @cwd

  # Determine stderr handling
  should_pipe_stderr = @options.stderr || @options.debug_stderr || @options.extra_args.key?('debug-to-stderr')

  begin
    # Start process using Open3
    opts = { chdir: @cwd&.to_s }.compact

    @stdin, @stdout, @stderr, @process = Open3.popen3(process_env, *cmd, opts)

    # Always drain stderr to prevent pipe buffer deadlock.
    # Without this, --verbose output fills the OS pipe buffer (~64KB),
    # the subprocess blocks on write, and all pipes stall → EPIPE.
    if @stderr
      if should_pipe_stderr # rubocop:disable Style/ConditionalAssignment
        @stderr_task = Thread.new do
          handle_stderr
        rescue StandardError
          # Ignore errors during stderr reading
        end
      else
        # Silently drain stderr so the subprocess never blocks,
        # but still accumulate recent lines for error reporting.
        @stderr_task = Thread.new do
          drain_stderr_with_accumulation
        rescue StandardError
          # Ignore — process may have already exited
        end
      end
    end

    # Always keep stdin open — streaming mode uses it for the control protocol
    @ready = true
  rescue Errno::ENOENT => e
    # Check if error is from cwd or CLI
    if @cwd && !File.directory?(@cwd.to_s)
      error = CLIConnectionError.new("Working directory does not exist: #{@cwd}")
      @exit_error = error
      raise error
    end
    error = CLINotFoundError.new("Claude Code not found at: #{@cli_path}")
    @exit_error = error
    raise error
  rescue StandardError => e
    error = CLIConnectionError.new("Failed to start Claude Code: #{e}")
    @exit_error = error
    raise error
  end
end

#drain_stderr_with_accumulation ⇒ Object 



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 282

def drain_stderr_with_accumulation
  return unless @stderr

  @stderr.each_line do |line|
    line_str = line.chomp
    next if line_str.empty?

    @recent_stderr_mutex.synchronize do
      @recent_stderr << line_str
      @recent_stderr.shift if @recent_stderr.size > 20
    end
  end
end

#end_input ⇒ Object 



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 397

def end_input
  return unless @stdin

  begin
    @stdin.close
  rescue StandardError
    # Ignore
  end
  @stdin = nil
end

#find_cli ⇒ Object

Raises:



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 33

def find_cli
  # Try which command first (using Open3 for thread safety)
  cli = nil
  begin
    stdout, _status = Open3.capture2('which', 'claude')
    cli = stdout.strip
  rescue StandardError
    # which command failed, try common locations
  end
  return cli if cli && !cli.empty? && File.executable?(cli)

  # Try common locations
  locations = [
    File.join(Dir.home, '.claude/local/claude'),  # Claude Code default install location
    File.join(Dir.home, '.npm-global/bin/claude'),
    '/usr/local/bin/claude',
    File.join(Dir.home, '.local/bin/claude'),
    File.join(Dir.home, 'node_modules/.bin/claude'),
    File.join(Dir.home, '.yarn/bin/claude')
  ]

  locations.each do |path|
    return path if File.exist?(path) && File.file?(path)
  end

  raise CLINotFoundError.new(
    "Claude Code not found. Install with:\n" \
    "  npm install -g @anthropic-ai/claude-code\n" \
    "\nIf already installed locally, try:\n" \
    '  export PATH="$HOME/node_modules/.bin:$PATH"' \
    "\n\nOr provide the path via ClaudeAgentOptions:\n" \
    "  ClaudeAgentOptions.new(cli_path: '/path/to/claude')"
  )
end

#handle_stderr ⇒ Object 



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 253

def handle_stderr
  return unless @stderr

  @stderr.each_line do |line|
    line_str = line.chomp
    next if line_str.empty?

    # Accumulate recent lines for inclusion in ProcessError
    @recent_stderr_mutex.synchronize do
      @recent_stderr << line_str
      @recent_stderr.shift if @recent_stderr.size > 20
    end

    # Call stderr callback if provided
    @options.stderr&.call(line_str)

    # Write to debug_stderr file/IO if provided
    if @options.debug_stderr
      if @options.debug_stderr.respond_to?(:puts)
        @options.debug_stderr.puts(line_str)
      elsif @options.debug_stderr.is_a?(String)
        File.open(@options.debug_stderr, 'a') { |f| f.puts(line_str) }
      end
    end
  end
rescue StandardError
  # Ignore errors during stderr reading
end

#read_messages(&block) ⇒ Object

Raises:



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 408

def read_messages(&block)
  return enum_for(:read_messages) unless block_given?

  raise CLIConnectionError, 'Not connected' unless @process && @stdout

  json_buffer = ''

  begin
    @stdout.each_line do |line|
      line_str = line.strip
      next if line_str.empty?

      json_lines = line_str.split("\n")

      json_lines.each do |json_line|
        json_line = json_line.strip
        next if json_line.empty?

        json_buffer += json_line

        if json_buffer.bytesize > @max_buffer_size
          buffer_length = json_buffer.bytesize
          json_buffer = ''
          raise CLIJSONDecodeError.new(
            "JSON message exceeded maximum buffer size",
            StandardError.new("Buffer size #{buffer_length} exceeds limit #{@max_buffer_size}")
          )
        end

        begin
          data = JSON.parse(json_buffer, symbolize_names: true)
          json_buffer = ''
          yield data
        rescue JSON::ParserError
          # Continue accumulating
          next
        end
      end
    end
  rescue IOError
    # Stream closed
  rescue StopIteration
    # Client disconnected
  end

  # Check process completion
  status = @process.value
  returncode = status.exitstatus

  if returncode && returncode != 0
    # Wait briefly for stderr thread to finish draining
    @stderr_task&.join(1)

    stderr_text = @recent_stderr_mutex.synchronize { @recent_stderr.last(10).join("\n") }
    stderr_text = 'No stderr output captured' if stderr_text.empty?

    @exit_error = ProcessError.new(
      "Command failed with exit code #{returncode}",
      exit_code: returncode,
      stderr: stderr_text
    )
    raise @exit_error
  end
end

#ready? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 494

def ready?
  @ready
end

#write(data) ⇒ Object

Raises:



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# File 'lib/claude_agent_sdk/subprocess_cli_transport.rb', line 381

def write(data)
  raise CLIConnectionError, 'ProcessTransport is not ready for writing' unless @ready && @stdin
  raise CLIConnectionError, "Cannot write to terminated process" if @process && !@process.alive?

  raise CLIConnectionError, "Cannot write to process that exited with error: #{@exit_error}" if @exit_error

  begin
    @stdin.write(data)
    @stdin.flush
  rescue StandardError => e
    @ready = false
    @exit_error = CLIConnectionError.new("Failed to write to process stdin: #{e}")
    raise @exit_error
  end
end