Father of twins. CTO @mercari_inc. Podcast at @e34fm
Tokyo-to, Japan
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本日7月1日付でメルカリのCTO Japan Businessに就任しました．
これまではSRE / Platform Engineeringとして技術基盤を，そして直近は越境事業において海外展開をエンジニアリングからリードしてきました．今後はCTOとしてJapan Business全体の技術戦略をリードしていきます．「組織と人」の面からAI-Native化を進めるCHRO/CAIOの @kimuras さ んと，「ものづくり」の面から連携しつつ，メルカリのAI-Native化をさらに進めていきます．
AIを前提とした新しい開発体制へと移行すること，そしてAIが最大限に力を発揮できるように，これまで作ってきた技術基盤とアーキテクチャそのものを作り変えていくこと，この2つを軸にものづくりのAI-Native化を推進していきます．そして越境事業を軸としたグローバルへの展開とそのための基盤の整備も引き続きリードしていきます．
よろしくお願いします!
株式会社メルカリ（以下、メルカリ）は、2026年7月1日付で、執行役員 VP of Engineering Cross Borderの中島大一が、執行役員 CTO Japan Business, VP of Engineering Marketplace New Businessに就任いたしましたので、お知らせいたします。
2026年6月1日付でCHRO（最高人事責任者） 兼 CAIO（最高AI責任者）に就任した木村俊也の後任として中島がCTOに就任いたします。CHRO 兼 CAIOの木村が「人と組織の運営基盤」をAI前提で再設計する役割に専念する一方、中島はCTOとして「ものづくりの基盤」をAI前提で再設計する技術変革を推進します。この2つを揃えることで、メルカリの「AI-Native Company」を一歩先の実行のフェーズに移行してまいります。
プレスリリース：about.mercari.com/press/news…
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There's been a ton of talk about the role of humans in code review, and when and how humans should be signing off on changes.
I believe that, long-term, humans have no role in routinely reviewing code.
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Taichi Nakashima retweeted
I am a sucker for good books, and so especially O'Reilly books.
Here's one that is WIP, but in return, it is free, thanks to @AntithesisHQ
It's for CTOs / eng leaders who want to get AI to deliver *business value* which is... tricky.
Get it here:
pages.antithesis.com/oreilly…
Paid partnership (ad)
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AI has collapsed the cost of building products, but not the cost of knowing what to build.
- The old loop: spec, scope, build
- The new loop: build, play, design, ship
Prototypes are cheap. Great products still require taste, judgment, and a clear understanding of what users actually need.
a16z's @joshelman on the artifact a product manager actually produces: a16z.news/p/product-manageme…
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現状のアラートが人間のOncallを前提に設定されてる (深夜に人を起こすコストを踏まえて) のでシグナルを厳しく設定してるが，AI Agentが一次受けしていく前提の中ではどんどん細いアラートも投げていけば良いってのは同じ考え．出力としてSlackにまとめるのではなくてPRのDiffのみが人間が見るべきものになる世界観にできると良いすな
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ちゃんとしたものができるまではコードレビューなどは気にしないでコミットしまくって動いてるものができてプレビュー環境で確認してから (Build wide) ，リファクタさせつつレビューしやすい/安全にロールアウトできる形にPRを分割させる (Ship narrow) アプローチ良さそう
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Taichi Nakashima retweeted
Introducing fx, a tiny, open, native coding agent from Vercel Labs.
Originally an internal tool, fx is a harness and CLI written in Zig, optimized for research and embedding in larger systems. Today, we're open sourcing it.
fx is built on three principles:
1. Fast. A single native binary, no runtime to install. It cold starts in 10µs and does no unnecessary work or I/O before accepting input. fx is the answer to "how fast can a coding agent be?"
2. Light. The 6.3MiB binary uses single-digit megabytes of memory at baseline, made for instant installation and embedding in resource-constrained environments and agent sandboxes.
3. Open. Apache-2.0, model and provider agnostic, suitable for local and cloud inference. Its small core extends through skills, plugins, and MCP.
Minimalism is an obsession throughout the entire harness: system prompt, tools, features, binary. The goal was to keep context usage and time to first token low, and make fx optimal for model benchmarking, sandboxing, evals, and gyms.
You can use fx directly or embed it as infrastructure. The CLI feels more like a Unix shell than an IDE in the terminal: it preserves scroll history, produces minimal output, and uses complex TUI rendering very, very sparingly. Programmatically, 𝚏𝚡 𝚊𝚜𝚔 --𝚓𝚜𝚘𝚗 gives structured output, 𝚏𝚡 𝚊𝚌𝚙 connects to editors and other clients, and WebAssembly can even run the whole thing inside the browser (see: fx.sh/try).
Privacy is a design constraint: no product telemetry, sessions and usage stay local, and no source code or prompts are shared with any endpoint other than inference. With local inference and auto-updates off, fx is fully hermetic.
fx is experimental. Use at your own risk and expect frequent changes. Chat with us on X (fx.sh/xchat) or file issues (fx.sh/issues).
𝚌𝚞𝚛𝚕 -𝚏𝚜𝚂𝙻 𝚏𝚡.𝚜𝚑/𝚜𝚎𝚝𝚞𝚙.𝚜𝚑 | 𝚋𝚊𝚜𝚑
fx.sh/
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