RLM.rb

Recursive Language Models for Ruby.

RLM.rb is a plain Ruby runtime for typed, sandbox-oriented, auditable AI jobs over large application context. It integrates with RubyLLM for provider calls and dspy.rb for typed signatures.

Status: the released gem is v0.2.0. The current main branch contains the plain Ruby runtime spine, real RubyLLM and dspy adapters, subprocess isolation, context skills, eval export, local evals, optimizer integration, caching, and telemetry. Rails integration remains a v2 milestone.

1. Large context breaks simple prompting.
2. Manual chunking and summarization are brittle.
3. Hand-rolled agent loops have unclear state, unclear cost, and poor auditability.

RLM.rb replaces those with a bounded runtime where the model explores context programmatically, calls smaller typed LLM functions only when needed, and returns validated Ruby objects with a full execution trace.

RLM.rb requires Ruby 3.3 or newer. Ruby 3.2 and older are not supported because dspy.rb is mandatory for the plain Ruby adapter milestone.

gem "rlm-rb"

require "dspy"
require "rlm"

class InvoiceExtraction < DSPy::Signature
  description "Extract normalized invoice fields from a vendor invoice."

  input do
    const :invoice_text, String
    const :vendor_id, Integer
  end

  output do
    const :vendor_name, String
    const :invoice_number, String
    const :total_cents, Integer
  end
end

RLM.configure do |config|
  config.root_lm = RLM::Lm::RubyLLM.new(model: "gpt-5-mini")
  config.sub_lm = RLM::Lm::RubyLLM.new(model: "gpt-5-mini")
  config.sandbox = RLM::Sandbox::Subprocess.new(timeout_seconds: 10)
end

result = RLM.predict(
  RLM::Signature::Dspy.new(InvoiceExtraction),
  input: {
    invoice_text: "Vendor: Acme\nInvoice: INV-001\nTotal: $100.00",
    vendor_id: 123
  },
  limits: RLM::Limits.new(max_iterations: 8, max_llm_calls: 25)
)

result.output
# => { vendor_name: "Acme", invoice_number: "INV-001", total_cents: 10000 }

For a deterministic no-provider test path, use RLM::Lm::Mock and RLM::Sandbox::UnsafeInProcess. The unsafe sandbox executes generated code in the host process and is only for dev/test.

• Interface: typed task contracts through RLM::Signature and RLM::Signature::Dspy.
• Inference: provider and model calls through RLM::Lm::*, including RLM::Lm::RubyLLM.
• Rendering: response protocols through tags, JSON, XML, provider-native JSON, and host-owned BAML adapters.
• Call graph: recursive runtime execution through RLM::Runtime, sandbox helpers, tools, and sub-signatures.
• Evals: trace/result export, local evals, and dspy optimizer entrypoints.

• Plain Ruby usage: configuration, live example, mock runtime, dspy signatures, and response protocols.
• Runtime features: trace stores, tools, skills, evals, dspy optimization, caching, and telemetry.
• Production notes: intended Rails setup, error handling, production safety, and development commands.
• Product requirements: long-form product direction and milestone notes.

The gem ships one opt-in live example:

bundle exec ruby examples/plain_ruby_invoice_extraction.rb

By default it exits before provider credential checks. To run the live path:

RLM_RUN_LIVE_EXAMPLE=1 OPENAI_API_KEY="$OPENAI_API_KEY" \
  bundle exec ruby examples/plain_ruby_invoice_extraction.rb

Set RLM_EXAMPLE_MODEL and RLM_EXAMPLE_SUB_MODEL to override the default models.

RLM.rb integrates with these upstream libraries:

• RubyLLM, chat guide for provider, chat, token, and cost APIs.
• dspy.rb, Signatures guide for typed input/output contracts.
• The Recursive Language Models reference implementation and DSPy RLM module for the underlying idea.

MIT, see LICENSE.txt.