Yusuke Ohashi

What Is Git Worktree, and Why It Matters Now

Thu, 05 Mar 2026 09:00:00 +0900

Why It Pairs Well with AI Agents

As AI-assisted development (Claude Code, Cursor, OpenAI Codex, and others) becomes more common, git worktree is getting attention again.

It has existed in Git for a long time, but it becomes especially powerful when multiple agents work in parallel.

Here’s what I want to cover:

what git worktree is
why it is getting attention now
why it works so well with AI agents

What Is Git Worktree?

git worktree lets you create multiple working directories from a single repository.

Keycloak: The Architect's Guide to Identity and Access Management

Thu, 22 Jan 2026 10:00:00 +0900

A comprehensive guide to Keycloak for software architects, covering authentication, authorization, and IAM best practices

Dotfiles

Tue, 28 May 2024 11:08:11 +0900

A comprehensive guide to managing dotfiles for consistent development environments across multiple machines

Writing C Compiler

Wed, 24 Aug 2022 02:50:09 +0900

A journey into compiler development: building a C compiler with tokenizer, parser, and code generator

Github Issue Driven Blog

Thu, 07 Jul 2022 13:29:23 +0900

I experimented automating my micro blog so that it’s generated from github issues.

In this blog post, I will show you how I redesigned my blogging workflow.

System Diagram

All piplines are run on github platforms.

Motivation

Normally, we google around issues, and paste code from stackoverflow. That’s it. Nothing more. However, there should be something we learned there. That’s what we should log.

I love blogging, but writing on my computer is somehow tedious. I need to establish publishing method that I can do on my mobile phone.

XCConfig

Tue, 12 Oct 2021 12:00:00 +0000

Externalize build information from Info.plist

SwiftDoc Action for Fastlane

Mon, 19 Jul 2021 06:01:57 +0000

I just want to announce I created a fastlane action for SwiftDoc, since I couldn’t find it in the fastlane official docs.

SwiftDoc is yet another documentation generator, and it’s dedicated for Swift project. It has very clean UI and also generates beautiful dependency graph. I introduced my private swift project.

Here is the script.

Place this script into fastlane/actions, and run in Fastfile

e.g.

    swiftdoc(
      input: "Sources",
      module_name: "YourModuleName",
      output: "docs/",
      base_url: "/",
      format: "html"
    )

You can publish it into github pages, netlify, and so on.

About

Mon, 12 Jul 2021 16:20:37 +0900

Hello, internet!

Welcome to my personal website. I am a software engineer in Tokyo, Japan.

My official name is “Yusuke Ohashi”, but I am also using “Michael Ling” or just “Mike” for communication. You can call me Mike, Yusuke, or Ohashi-san(if you prefer japanese style).

This is yet another static website built on top of hugo, but is leveraged by a bunch of tech stacks to streamline my blogging. See more details at this post.

How I built this blog

Wed, 30 Jun 2021 06:49:42 +0000

This is a snapshot as of 2021/6. I will write about this blog. This digram shows my blog architecture.

Core

I am running this blog on linode VPS. This blog is in a docker container and I am using dokku to manage containers(apps). Dokku is script based Paas and an OSS. Heroku buildpacks are compatible with Dokku since it’s a heroku alternative. Thanksfully, you can run any applications on Dokku just by pushing your code.

Make Comment Great Again

Fri, 18 Jun 2021 08:04:24 +0000

I haven’t use comment feature on this weblog, but I really wanted to implement it. I have tried Disqus. It was cool but it turned out that it didn’t match my needs.

Thought of Disqus

Disqus has rich UI and features to discuss blog posts, but it allows

anonymous comments
Ads inclusion

For anonymous comments, my blog thanksfully has almost no comments from readers. However, recently a lot of celebrities receive relentless aggresive comments, and ended up suffering from mental disorder. No one tells that this won’t happen on this tiny personal blog.

NWPathMonitor

Mon, 14 Jun 2021 16:16:05 +0900

Introduction

NWPathMonitor is a class in Network framework, which observes network status and monitor network interface. It’s available in iOS 12 or later.

import Network

You must retain NWPathMonitor instances to get callbacks.

class NetworkMonitorViewController: ViewController {
    let monitor = NWPathMonitor()
}

requiredInterface lets you observe the specific network interface.

let wifiMonitor = NWPathMonitor(requiredInterfaceType: .wifi)

Here is the list of interfaces that NWPathMonitor supports.

https://developer.apple.com/documentation/network/nwinterface/interfacetype

Detect network changes

monitor.pathUpdateHandler = { path in
    if path.status == .satisfied {
        // Connected
    }
}

Start observation

Create a background queue, then pass it to start().

Portfolio

Fri, 01 Jan 2021 00:00:00 +0000

Selected projects and links.

Munin Installation Memo

Tue, 21 Apr 2020 07:02:57 +0000

Have you ever listened to Munin? Munin is a server resource monitoring tool, which provides graphical interfaces for a bunch of data

Munin is quite simple and easy to set up.

Here, I will write down my configuration when I set up munin lately. I suppose that you are using Ubuntu 18.04 LTS.

$ sudo apt update
$ sudo apt install munin munin-node nginx

Nginx Configuration

server {
        listen 80 default_server;
        listen [::]:80 default_server;

        root /var/www/html;

        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;

        server_name _;

        location /munin {
            alias /var/www/html/munin;
        }

        location ^~ /munin-cgi/munin-cgi-graph/ {
            access_log off;
            fastcgi_split_path_info ^(/munin-cgi/munin-cgi-graph)(.*);
            fastcgi_param PATH_INFO $fastcgi_path_info;
            fastcgi_pass unix:/var/run/munin/fastcgi-graph.sock;
            include fastcgi_params;
        }

}

Restart nginx.

LSP for Swift

Tue, 07 Apr 2020 18:01:03 +0900

What is Language Server Protocol(LSP)?

Language Server Protocol defines standardized protocol with which both a text editor or IDE(client) and a language(server) communicate.
The protocol is based on JSONRPC.
A client(text editor) can implement
- Go to definition
- Error and warnings
- Auto completion
- …

https://microsoft.github.io/language-server-protocol/overviews/lsp/overview/

Solves m-times-n complexity problems

What is Sourcekit-LSP?

Apple’s LSP implementation on top of sourcekitd and clangd
sourcekitd is a framework that provide IDE features
clangd for c-family languages (C/C++/ObjC) language server
supports only Swift Package Manager project

As of Xcode 11.4, SourceKit-LSP is a built-in tool.

2018 in review

Fri, 11 Jan 2019 00:00:00 +0000

2018 was yet another awesome year.

Commitments in work

I worked on building mobile development foundation.

Jenkins CI Exapansion

I read this book to learn Jenkins(written in Japanese). Aside from maintaining jenkins, I learned to modify several Jenkins modules, such as Git plugin.(We are using my forked Git plugin now.)

Open API Specification

OpenAPI Initiative

Side projects

This blog

I moved this blog to Linode. What I exactly did is that I moved my blog on docker on Linode instance.

Network Abstraction Layer

Sat, 10 Nov 2018 00:00:00 +0000

I am experimenting a new way for network request in Kiri library. Kiri is Moya inspired abstract networking layer. I was very impressed by Moya architecture, so to learn from it the most, I decided to trace the same architecture by writing by myself, instead of copy and paste. :D

We need to break down client library into three parts.

Request

Normally, you have to construct networking request every time. Instead, in Kiri, your network configuration is compiled in one place, like class, enum. And the class, enum must conform to RequestContainer protocol.

Crontab Guru

Wed, 12 Sep 2018 00:00:00 +0000

If you use google whenever you write crontab, this website is good for you.

crontab guru

Crontab format is not intuitive. This website tells you how your cron will work. You can input your own cron job in the rounded textfield, and you can check how it works before you start on your server. It will help you avoid significant mistakes before deploying your job.

NPM Dependency Graph

Tue, 11 Sep 2018 00:00:00 +0000

I found the awesome tool to visualize npm dependency graph.

This example shows dependency graph of react-native-maps, which I was investigating last night.

https://npm.anvaka.com/#/view/2d/react-native-maps

2D

You can drag nodes, and highlight node with cursor on.

3D

You can rotate graph, but 3D doesn’t show module names.