Class: Brute::Completion::LangChain

Inherits:
Object
  • Object
show all
Includes:
Hooks
Defined in:
lib/brute/completion/lang_chain.rb

Overview

Completion backed by the langchainrb gem (https://github.com/patterns-ai-core/langchainrb). Its LLM classes wrap many providers; build one and hand it over:

Brute.agent
.use(Brute::Middleware::SystemPrompt)
.run(Brute::Completion::LangChain.new(
  llm: Langchain::LLM::OpenAI.new(api_key: ENV["OPENAI_API_KEY"]),
))

llm:         a Langchain::LLM instance (required; client: is an alias)
model:       model id override (falls back to env[:model], then the
           llm instance's own default)
tools:       tools list, any shape Tools::Adapter accepts
temperature: sampling temperature (default 0.7)

Constant Summary collapse

DEFAULT_TEMPERATURE = 
0.7

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(llm: nil, client: nil, **options) ⇒ LangChain

Returns a new instance of LangChain.



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# File 'lib/brute/completion/lang_chain.rb', line 29

def initialize(llm: nil, client: nil, **options)
  # Brute depends on no LLM library: the provider gem is required here,
  # at point of use, and only for this completion.
  begin
    require "langchain"
  rescue LoadError
    raise LoadError, "#{self.class} needs the 'langchainrb' gem — add `gem \"langchainrb\"` to your Gemfile."
  end

  @llm = llm || client or
    raise ArgumentError, "#{self.class} needs an llm: option, e.g. Langchain::LLM::OpenAI.new(api_key: ...)"

  @options = options
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/brute/completion/lang_chain.rb', line 44

def call(env)
  env.emit_trace do |env|
    env.emit(LLM_START_EVENT)

    response = nil
    env.emit(LLM_DURATION_EVENT) { response = @llm.chat(**params(env)) }

    if (usage = Brute::MessageTransport::LangChain.usage_metrics(response))
      (env[:metadata] ||= {})[:last_llm_usage] = usage
    end

    # langchainrb speaks the OpenAI-style wire format both ways.
    Brute::MessageTransport::LangChain.wrap_each(reply(response)) do |message|
      env[:messages] << message
    end

    env.emit(LLM_END_EVENT)
  rescue => error
    env.emit(LLM_FAILURE_EVENT)

    if defined?(::Faraday::Error) && error.is_a?(::Faraday::Error)
      env.emit(FARADAY_ERROR_EVENT, error)
    else
      env.emit(STANDARD_ERROR_EVENT, error)
    end

  end
  env
end