$ whoami
I'm Leonid, a software engineer. For 15+ years, I've worked with founders to figure out what they need, build it, and keep it running. I like asking questions before writing code and helping other developers grow. These days, I build with coding agents and share much of my work as open source.
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STACK
├── uptime: 15+ yrs- ruby / rails 10+ years, lead roles 10+ years. Tech lead and lead engineer roles. Gem author.
- typescript full-stack Full-stack: Node, browser extensions, static sites.
- python data, LLMs, trading Data pipelines, LLMs and trading systems.
- agentic ai skills, harnesses, pipelines Skills, harnesses, pipelines and tooling for real delivery.
2026-10-06 Handrail: write your guardrails once, enforce them everywhere Share guardrails across Claude Code, Codex, and oh-my-pi with a single rule definition, evaluated by native hooks at event time. read → 2026-09-26 Three agentic skills I wish I'd started using sooner improve-tests, debrief-skill, and retro: three agent skills that handle the maintenance work that always loses to something urgent, from slow test suites to friction in skills and tooling. read → 2026-09-23 ArchSpec: when your AI agent doesn't know your rules, make the rules unbreakable ArchSpec turns Rails architecture conventions into rules that CI enforces, so code from AI agents, new hires, and seniors alike has to respect your layer boundaries. read → 2026-09-22 Agent shortcuts: aliases for your AI coding agent Shell-style shortcuts for Claude Code and Codex: commit, push, open pull requests, fix CI, and keep common agent workflows predictable. read → 2026-09-21 System 1 AI models: the idea that existed before Jev, and why you should use it anyway System 1 models separate structured decisions from text generation. A look at Jev, earlier research, open models, and five possible applications. read →
sec_id/ Ruby Ruby toolkit for securities identifiers: ISIN, CUSIP, SEDOL, FIGI, LEI and 11 more schemes. Ruby handrail/ Go Declare an agent guardrail once, in one neutral format, and enforce it through every harness's native hooks. Go hacker_news_sorted/ TypeScript Chrome extension that sorts Hacker News by points, time, comments, velocity or heat. TypeScript database-transactions/ TypeScript Learn database transactions from verified, runnable examples. Every claim proven against a real PostgreSQL/MySQL database. TypeScript clsx-rails/ Ruby The fastest conditional CSS class builder for Rails. 2-4x faster than class_names. Ruby supermatt/ Skills AI coding-agent workflow covering planning through shipping, with built-in testing and code review verified by a second model when available. Skills