John Costa — Engineer, leader, builder.
I turn ambiguity into shipped products. I've spent over a decade in startups as an IC, tech lead, and engineering director, working on everything from site reliability to full-stack feature development. I go wherever the work needs me and partner across teams to find opportunities that wouldn't exist if no one was looking. Today I'm pushing AI-augmented building and contributing to open source tools that give back. More about me →
Writing
Recent thinking
Your Team Needs a Code Review Canon
On shared standards, accountable review, and what AI changes about both
100 Merged PRs: What I Learned Contributing to Open Source with AI
On persistence, ownership, and shipping code in languages I don't know
From Raspberry Pi to 17-Container Homelab in Six Months
Replacing streaming subscriptions with a self-hosted media server, book library, and monitoring stack, built in a weekend
You Were Never Typing Code
The job was never typing. It was choosing the right pattern and reviewing what ships.
AI Is Bringing Developers Back to the Terminal. Ink Is Making It Beautiful.
How a 36K-star React renderer quietly powers your favorite CLI tools
Building a Self-Improving Trading System With AI
An AI agent that reviews its own performance, runs experiments, and deploys improvements. Autonomously.
Automate Your Life With Cron Jobs, GitHub Actions, and Telegram
Scheduled jobs, free tools, and a little AI can quietly run a surprising amount of your life
Your Portfolio Site Deserves a Pipeline
I rebuilt my personal site as plain HTML with zero frameworks. Then I gave it a real data pipeline so it never goes stale.
Claude Code Tips and Tricks
For AI-Assisted Engineering
The Biggest Bottleneck in Enterprise Software Isn't Technical
The Coordination Tax
Why Functional Programming Is the Most Important Skill for the AI Era
What type-driven design, declarative thinking, and domain modeling have to do with AI
How to Have a Career in 2026
A step-by-step guide for leveraging AI in any job function
What It Takes to Be a Software Engineer in 2026
AI made implementation easier. Here's how to stay valuable.
AI Drives, You Direct
How I finally started getting PRs merged
Why AI-Assisted Development Feels Like Engineering Management
How years of code review prepared me for working with Claude
AI-Assisted Home Automation in 2026
With Home Assistant and Claude Code
Modeling React State as a Finite State Machine
A modern approach using TypeScript discriminated unions and hooks
Open Source
Building in the open
Contributing to the tools developers rely on and the software that serves communities
Recently merged
Show target platform instead of host in cross-platform export
conda/conda-libmamba-solver#911
Fix `prefer-top-level-await` under `@typescript-eslint/parser`
sindresorhus/eslint-plugin-unicorn#2948
DEV: Align mypy Makefile target with strict mode
py-pdf/pypdf#3690
fix(translations): expand fr registry in DEFAULT_PARAM_TRANSLATIONS
mampfes/hacs_waste_collection_schedule#6087
fix(persistence): increase IndexedDB retry window for session-restart locks
super-productivity/super-productivity#7220
Projects
What I'm building
oss-autopilot
An AI-powered autopilot for managing open source contributions. It tracks PRs, responds to maintainers, discovers new issues, and helps maintain velocity. Built as a Claude Code plugin that makes sustained OSS contribution practical.
alpaca-trader
A self-evolving automated trading system that combines sentiment analysis, insider signals, and AI-driven position management. It learns and adapts over time.
mermaid-to-pdf
A CLI and MCP tool that converts Markdown files with Mermaid diagrams into PDF. Works standalone or as an AI-accessible tool via Model Context Protocol.