Technical articles, software engineering, and daily learnings
A development diary of isutools, an ISUCON profiler built in one day. It started as a teammate's everyday SQL logger; lacking the skill and time to extend it by hand, I leaned on Claude Code and Codex, with a design-doc-first, TDD, dogfooding workflow. Includes the honest open questions: am I actually learning, and will any of this matter in a real contest?
Read moreISUCON measurement usually means juggling alp, pt-query-digest, pprof, and top. isutools is a Go OSS that collects SQL, HTTP, nginx logs, per-process CPU, DB schema, and pprof into one dashboard with a single sqlx.Open rewrite. Overhead measured at -0.58% (within noise). Setup and full feature tour.
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I entered the Combined Track of League of Robot Runners 2026 — the Amazon Robotics-sponsored multi-robot path planning contest — as the one-person team Rovnou, finishing 8th of 68 teams (score 5.55, 134,905 tasks completed). Notes on the lifelong MAPF problem, a planner stack organized by timescale, and an honest breakdown of the gap to first place.
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A full log of tuning private-isu (Go) from a score of 0 to 541,650 in a single day. Every fix was driven by isutools, an open-source profiling module I built along the way — indexes, N+1 elimination, nginx tuning, caching, and pre-rendering, step by step.
Read moreProject Hail Mary is very good at one of the hardest things in science fiction: making an unknown lifeform feel genuinely new. The best thing in the novel, to me, is not the ending, and not even the friendship at its center. It is the discovery of Astrophage.
Read morePractical lessons from rewriting a KPI definition document 5 times. Start with KGI, write hypotheses first, avoid the bounce rate trap, and speak business impact in dollars.
Read moreRebuilt my existing blog with Next.js 16 + MDX + Tailwind CSS v4. Auto WebP compression on image paste, build-time OGP generation, zero-runtime SSG—technical choices designed to let me focus on writing.
Read moreBuild a speaker diarization and transcription pipeline with AWS Step Functions + Lambda. ~$2/month fixed cost, ~$2.3 for an 8-hour video — about 5x more cost-efficient than AWS Transcribe.
Read moreGTM Custom HTML tags only support ES5 JavaScript. I built a Claude Code Skill to bridge the gap between AI-generated ES6+ code and GTM's constraints.
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