Class: Brute::Middleware::DefaultToolPipeline

Inherits:
Base
  • Object
show all
Defined in:
lib/brute/middleware/070_default_tool_pipeline.rb

Constant Summary

Constants included from Hooks

Hooks::COMPACT_DURATION_EVENT, Hooks::COMPACT_END_EVENT, Hooks::COMPACT_FAILURE_EVENT, Hooks::COMPACT_START_EVENT, Hooks::CONTENT_EVENT, Hooks::FARADAY_ERROR_EVENT, Hooks::LLM_DURATION_EVENT, Hooks::LLM_END_EVENT, Hooks::LLM_FAILURE_EVENT, Hooks::LLM_START_EVENT, Hooks::MIDDLEWARE_ADDED_EVENT, Hooks::MIDDLEWARE_DURATION_EVENT, Hooks::MIDDLEWARE_END_EVENT, Hooks::MIDDLEWARE_FAILURE_EVENT, Hooks::MIDDLEWARE_START_EVENT, Hooks::OPEN_ROUTER_SERVER_ERROR_EVENT, Hooks::REASONING_EVENT, Hooks::STANDARD_ERROR_EVENT, Hooks::TOOL_APPROVE_EVENT, Hooks::TOOL_CALLS_EVENT, Hooks::TOOL_DURATION_EVENT, Hooks::TOOL_END_EVENT, Hooks::TOOL_FAILURE_EVENT, Hooks::TOOL_START_EVENT, Hooks::TURN_DURATION_EVENT, Hooks::TURN_END_EVENT, Hooks::TURN_FAILURE_EVENT, Hooks::TURN_START_EVENT

Instance Method Summary collapse

Constructor Details

#initialize(app, tools: []) ⇒ DefaultToolPipeline

Returns a new instance of DefaultToolPipeline.



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# File 'lib/brute/middleware/070_default_tool_pipeline.rb', line 12

def initialize(app, tools: [])
  @app   = app
  @tools = tools
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/brute/middleware/070_default_tool_pipeline.rb', line 17

def call(env)
  env[:tools] = @tools
  @app.call(env)

  response = env[:messages].last

  if response.respond_to?(:tool_calls) && response.tool_calls.present?
    tools_to_run = response.tool_calls

    # tool_to_run may be an Array (Brute::ToolCall) or an id-keyed Hash (some libraries' native shape)
    if tools_to_run.respond_to?(:values)
      tools_to_run = tools_to_run.values
    end

    # No idea why we use Array() here... probably in case it's a hash or something...
    # because reject would work on the hash...
    tools_to_run = Array(tools_to_run).reject { |tc| tc.name == "question" }

    available_tools = Brute::Tools::Adapter.wrap_all(env[:tools])
    env.emit(TOOL_CALLS_EVENT, tools_to_run)

    results = []

    # Async::Barrier blocks until all tasks are complete.
    # Tasks run in parrallel.
    #
    Sync do
      barrier = Async::Barrier.new

      tools_to_run.each do |tool_call|
        barrier.async do
          name = tool_call.name.to_sym
          args = tool_call.arguments

          # Lifecycle hooks (Brute::Hooks): tool_start may rewrite
          # :arguments or short-circuit with a :result; tool_approve
          # denies on a false (or String) return; tool_end may
          # rewrite :result.
          call_env = {
            name:      name.to_s,
            arguments: args,
            result:    nil,
            denied:    nil,
            metadata:  {},
            turn_env:  env,
          }
          env.emit_trace do |env|
            # A subscriber takes part by mutating the call env: set
            # :result to answer without executing, set :denied to refuse.
            env.emit(TOOL_START_EVENT, call_env)

            if call_env[:result].nil?
              env.emit(TOOL_APPROVE_EVENT, call_env)

              if (denial = call_env[:denied])
                if denial.is_a?(String)
                  call_env[:result] = denial
                else
                  call_env[:result] = %(Tool call to "#{name}" was denied.)
                end
              end
            end

            # Only the tool's own execution is timed: a call that
            # tool_start answered, or tool_approve denied, never ran.
            result = call_env[:result]

            if result.nil?
              env.emit(TOOL_DURATION_EVENT, call_env) do
                result = available_tools[name].call(call_env[:arguments])
              end
            end

            call_env[:result] = result
            env.emit(TOOL_END_EVENT, call_env)
          rescue => error
            # Capture the error as a tool result so the LLM can see it
            # and reason about the failure, rather than crashing the
            # entire middleware chain.
            env.emit(TOOL_FAILURE_EVENT, call_env, error)
            call_env[:result] = "Error: #{error.class}: #{error.message}"
          end
          result = call_env[:result]

          # Coerce to String so Hash results (e.g. Shell's
          # {stdout:, stderr:, exit_code:}) serialize predictably.
          if result.is_a?(String)
            content = result
          else
            content = result.to_s
          end

          # Universal truncation safety net — skip if already truncated
          unless Brute::Truncation.already_truncated?(content)
            content = Brute::Truncation.truncate(content)
          end

          results << [tool_call, content]
        end
      end

      barrier.wait
    ensure
      barrier&.cancel
    end

    # Append events and messages in the original tool_call order so the
    # LLM sees a deterministic sequence regardless of completion order.
    results.sort_by! { |tool_call, _| tools_to_run.index(tool_call) }

    results.each do |tool_call, content|
      env[:messages] << Brute::Message.new(role: :tool, content: content, tool_call_id: tool_call.id)
    end
  end

  env
end