John Detlefs

Production systems and debugging war stories

Senior Software Engineer · Reliability & Growth

I build the systems behind the buy button.

Seven years of shipping customer-facing software where downtime costs real money. At GoDaddy I helped evolve the dashboard and account surfaces behind $200M+ in annual revenue, cutting p95 latency and improving experiment quality across millions of sessions. At PwC (via Kunai) I build cloud infrastructure for nine-figure consulting engagements.

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jdetle/guardian — agent resource monitoring for Cursor and Codex on macOS

April 14, 20263 min read

Guardian at github.com/jdetle/guardian is a macOS stack for AI coding agents (Cursor and OpenAI Codex today): sampling, hooks, and policy so the host’s real load shows up in every session. Status — AI draft: I have not done my own pass on t…

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Browser fingerprint demo — same canvas hash as the full page, wired into analytics.

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Recorded interactions (merged events for your fingerprint, cap 100)

Canvas fingerprint

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GitHub

GitHub commit activity over the last year

Recent public commit activity. github.com/jdetle

Guardian

Rust · Open source

Framework-agnostic monitor for agentic resource consumption: tracks CPU, memory, and disk so long-running coding agents stay within bounds, independent of editor or agent stack. github.com/jdetle/guardian

Currently at Kunai (PwC Network) as a Senior Cloud Developer. Previously Senior SDE at GoDaddy. Before that: full-stack across IoT (Meshify), crypto, and data tooling.

  • TypeScript / React / Next.js
  • AWS / Cloud Infrastructure
  • Node.js / Rust
  • Observability / SRE
  • Performance / Experimentation