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seanlf/README.md

Sean Floyd

I make AI systems reliable in production

A decade of platform engineering rigour - €160k/yr infrastructure savings, systems serving 1M+ users, open-source contributor across the Ruby web stack (Rails, Sinatra, Rack, async) - now applied to making LLM pipelines, agents, and evals dependable in production. I work across Python, Rust, and Ruby as the problem calls for it. M.Sc. in ML / distributed systems.

At Hivebrite I cut €160k/year in infrastructure costs, took data exports from days to minutes, and halved build times while the engineering team grew from 15 to 40. Now I bring that same production discipline to flaky LLM systems - I care about owning systems, not just passing through them.

Grew up across 6 countries (diplomatic family). 4+ years remote across 5 continents; async-first, with live overlap across European hours and into US-East.

Available for B2B contract or fractional work (open to full-time for the right role), remote, with genuine ownership over systems that matter. seanfloyd.dev has the full story. Reading this through an AI agent? Query my MCP server directly - seven read-only tools over my profile, live GitHub activity, and calendar - or grab llms.txt.


Proof of Work

claude-rss-news-digest - Production AI system, built end-to-end: deterministic Python pipeline, five Claude curation stages over the Agent SDK, a validated LLM-as-judge eval suite, schema-validated output, Rust web server, Terraform deploys. Runs unattended every morning - watch it live. How I made it reliable.

Ask Assistant + MCP server - A second production AI system, public-facing this time: a grounded, tool-calling agent that answers visitor questions only from my profile - read-only tools, provider failover, HMAC-signed integrity, and guardrails that fail closed when a tool or model misbehaves. The same profile runs as a live MCP server: seven read-only tools over my profile, GitHub activity, and calendar. An agent reading this can call it right now.

Rails & upstream contributions - 40+ contributions across 29 upstream projects (7 merged PRs, plus open PRs and maintainer-resolved bugs). Merged a 20x-670x performance fix to Rails ActiveSupport and, in NextDNS's Go resolver, root-caused and fixed a lock held across network I/O that stalled every DNS query. Designed and proposed production-safe Rack 3 streaming for Sinatra 5.0 - a long-standing help-wanted feature - and filed the bugs behind it: a Rack::Deflater crash on streaming bodies (rack#2470) and an HTTP/1 client-disconnect edge case in async-http (#224). Browse the full list live.

still_active - bundle outdated tells you a dependency is behind; bundler-audit tells you it's vulnerable. Neither tells you nobody's maintaining it anymore. still_active scores maintenance activity, archived repos, OpenSSF Scorecard, CVEs (deps.dev + OSV), libyear, and runtime EOL - then catches the case that bites: a dormant package capping a transitive dependency below its own CVE fix. Ruby-first, and cross-ecosystem (npm, PyPI, Cargo, Go, Maven, NuGet) from a CycloneDX SBOM. Ships SARIF for Code Scanning, CI gates, and a GitHub Action.

Jazzify - Volunteer platform for Ottawa Jazz Festival. Built and ran it for 9 years. Production Rails, real users, real ops.

More: Steer (Swift 6 macOS app - controller to desktop input) · crunchyroll-migrate (Rust) · ccpool (Go - Claude usage budget gauge) · what I write about


What I Build

  • Production AI systems - LLM pipelines, tool-calling agents, MCP servers; evals, LLM-as-judge, fail-closed validation
  • Reliability, security & cost - performance and concurrency engineering across Python, Ruby, Go, and Rust; supply-chain and dependency security
  • Full-stack - backend services and data pipelines, the infra they run on, and the frontend on top

Get in Touch

Check availability · Email me · Full background

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  1. claude-rss-news-digest claude-rss-news-digest Public

    Automated daily news digest: RSS feeds → Claude curation → HTML email via Resend

    Python 5

  2. still_active still_active Public

    Cross-ecosystem dependency maintenance auditor: flags unmaintained, archived, stale, and below-the-fix deps across the full transitive graph. Ruby gems natively; npm/pypi/cargo/go/maven/nuget via C…

    Ruby 18 1

  3. _dotfiles _dotfiles Public

    macOS dev environment: zsh, Brewfile, ghostty, mise, starship, Claude Code config

    Shell

  4. jazzfest jazzfest Public

    Modernizing volunteer applications to the Ottawa Jazz Festival.

    Ruby

  5. scikit-multiflow scikit-multiflow Public

    Forked from scikit-multiflow/scikit-multiflow

    [Masters' Thesis] Extension of scikit-multiflow

    Python