The Ruby AI Podcast

Active Agent with Justin Bowen


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Seventeen-year Ruby veteran Justin Bowen joins hosts Valentino Stoll and Joe Leo to unveil Active Agent—a Rails-native framework that treats every agent like a controller and every prompt like a view, letting you weave LLMs, vector search, and business logic straight into MVC.

The crew also digs into the real-world mechanics of shipping AI: defining ground-truth datasets, replay-ready evaluation harnesses, and tight retry logic that keeps hallucinations out of production. You’ll hear a candid take on the current hype cycle (and its parallels to crypto), the challenges of long-term gem maintenance, and fresh ways to keep open-source sustainable—think GitHub Sponsors, corporate grants, and pro-tier gems.

What you’ll hear

  • Active Agent 101 – agents as abstract controllers, templated prompts as views
  • Testing in the wild – fingerprints, VCR cassettes & CI pipelines for non-deterministic code
  • Context is king – why ground truth matters when counting cows or parsing legal docs
  • OSS meets ROI – balancing passion projects with sustainable monetisation
  • Rails vs. Python/Next.js – reclaiming the one-person startup stack
  • Community fuel – Discords, hackathons, and the push for academic & corporate sponsorship

Mentioned In The Show:

  • Active Agent (GitHub)  – Justin’s Rails-native, agent-oriented framework for building AI features.
  •  Vercel AI SDK  – TypeScript toolkit whose generative-UI ideas helped inspire Active Agent.
  •  Maestra.ai  – YC W24 startup offering AI transcription, dubbing, and hosted agent runtimes.
  • Matz's 2025 Ruby Kaigi AI Keynote
  •  ONNX Runtime Ruby  – Gem that runs ONNX models (CPU/GPU) from Ruby.
  •  PGVector gem  – Ruby bindings for PostgreSQL’s pgvector extension (embeddings storage).
  •  Neighbor gem  – k-NN / ANN vector search for Rails & Postgres—pairs nicely with PGVector.
  • Hugging Face JS – Run models in the browser with WebGPU and ONNX 
  •  Hugging Face Spaces  – No-config platform for hosting ML demos; handy for sharing agent prototypes.
  •  LangSmith (LangChain)  – Evaluation & observability service discussed as a monetization model.
  •  CrewAI (GitHub)  – Python framework for orchestrating multi-agent “crews”; Joe’s current go-to.
  •  Honeybadger  – Rails-first error-monitoring SaaS—an inspiration for future Active Agent services.
  • Rising Impact – A Netflix anime special about a third-grader's journey to be the world's best golfer.
  •  Osmo AI  – Google-born startup using AI to digitise smell—cited in the show’s “AI hype” chat.
  •  Ruby AI Builders Discord  – Public Discord community for Rubyists building AI apps.
...more
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The Ruby AI PodcastBy Valentino Stoll, Joe Leo