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yhay81/README.md
Yusuke Hayashi — engineering systems that ship

Portfolio · Haya Inc. · Zenn · LinkedIn · Email

Software engineer × product builder, based in Tokyo.
I turn ambiguous problems into production systems—architecture, implementation, evaluation, delivery, and operation.

01 / AI SYSTEMS

LLM integration, RAG pipelines, evaluation, and human-in-the-loop workflows designed for production constraints.

LLM RAG EVALS
02 / SYSTEMS & TOOLING

Small, dependable developer tools with clear APIs, native performance, and low operational cost.

PYTHON RUST APIs
03 / DELIVERY

Cloud architecture, CI/CD, observability, and team practices that carry software safely into operation.

CLOUD CI/CD OPS

Proof of work

Project Engineering signal Live OSS telemetry
pylopdf Python ergonomics over a Rust PDF core; small wheels and zero runtime dependencies. ★ 1 forks 0 · Python / Rust
GASlacker A production-minded Slack Web API client: 168 methods, rate-limit retries, uploads, and OAuth v2. ★ 30 forks 10 · TypeScript / GAS
public-data-catalog AI-friendly public API and dataset metadata, published in machine-readable form. ★ 0 forks 0 · Python / Data

Current operating loop · frame the problem → model the system → ship a thin slice → measure reality → harden what matters

At Haya Inc., I work on production AI adoption and the engineering systems around it—from technical framing through rollout and team enablement.

Engineering footprint

Integrated GitHub engineering metrics for Yusuke Hayashi

First-party public GitHub signals, regenerated daily with a versioned API and no coding-time vanity metrics.

Latest writing


Outside work, I am usually on a road bike. For consulting, product engineering, or AI adoption inquiries, visit Haya Inc. or get in touch.

Pinned Loading

  1. hayatepy/hayate hayatepy/hayate Public

    Web-standards-first Python framework: WHATWG Fetch / URL / URLPattern across ASGI, Cloudflare Workers, and AWS Lambda

    Python 1

  2. haya-inc/wasmhatch haya-inc/wasmhatch Public

    The AI assistant that actually does the work — right in your browser tab. No server, no install, no account. Bring your own key or use Chrome's built-in AI; creates Google Docs, Sheets, and Slides;…

    TypeScript 1 6

  3. pylopdf pylopdf Public

    PDF editing and rendering for Python, powered by Rust (lopdf + hayro). MIT, zero dependencies, lightweight wheels.

    Python 2

  4. socialname socialname Public

    SocialName: Yet Another fork of Sherlock

    Rust 1

  5. haya-inc/hayasend haya-inc/hayasend Public

    Customer-owned email safety and reliability control plane. Resend-compatible on AWS today, with provider-neutral conformance next.

    TypeScript 2

  6. sqrail sqrail Public

    A minimal SQL-on-files CLI for coding agents. SQL in, files out.

    C++ 1