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I bought it on Kindle on February 20, 2026, and finished reading it on July 19. It took me quite a while. AWSコンテナ設計・構築［本格］入門 増補改訂版 amazon.co.jp I’d used ECS before, but I’d never built anything from scratch with it at work. Since it looks like I’ll be working with ECS soon, and my last hands-on experience was a long time ago, I picked this up to catch up on the current state of things. The fact that it comes with hands-on exercises was another deciding factor. ...

I added an IIJmio eSIM on the au (KDDI) network to the Pixel 9a I bought in [2025-05-04-1] , making it a dual SIM setup. I did this on May 17 (Sun). Why I Added an eSIM I had been using IIJmio’s docomo network with a physical SIM for a long time, but the signal was often poor. I went back and forth between “switching the docomo line to au” and “adding an au line,” and for now I went with adding one. Here’s why: ...

For a long time I’d been using railwaycat/homebrew-emacsmacport , a build of Emacs with the Mac port patches applied. Why I Switched to the NS Build Over the past few years, though, I’d been feeling the following pain points. The Mac port hasn’t kept up with the latest Emacs The current latest Emacs is 30.2, but the Mac port only supports 29.4 With the latest railwaycat/homebrew-emacsmacport release, emacs-29.4-mac-10.1 , I ran into the problem in issue #389 on my setup, so I’d been sticking with the previous emacs-29.1-mac-10.0 Ideally, I’d like to use the latest Emacs The only reason I used the Mac port build in the first place was to automatically turn off Japanese input when I hit M-x and the like, then restore it to its original state afterward. Here’s the configuration . ...

I mostly use Claude Code, but lately I’ve been using Codex CLI and Codex.app (hereafter “Codex”) more often too. My environment is macOS. However, after I started using mise in [2026-03-29-1] , I ran into trouble because Codex wouldn’t use the mise-managed Ruby, Node.js, and so on. Here’s the state I was in: $ where ruby /usr/bin/ruby $ ruby --version ruby 2.6.10p210 (2022-04-12 revision 67958) [universal.arm64e-darwin25] The Solution I solved it by adding the following to ~/.zshenv: ...

Here’s a summary of how I currently use Claude Code . I previously introduced a Claude Code book in [2026-01-16-1] , but this time I’ll write about my own workflow. Development Environment I work on my MacBook’s built-in display. I’m not really someone who uses external monitors. I display the macOS built-in Terminal.app in full screen and use tmux . I don’t split tmux windows—instead, I switch between tabs (windows). I haven’t (yet?) switched to Ghostty or iTerm2 . ...

For managing versions of development tools like Ruby and Node.js, I had gone through *env tools like rbenv and nodenv , then switched to asdf in 2019. For environment variable management, I had been using direnv since even earlier—2014. Recently, a tool called mise has been gaining attention. I wasn’t particularly having issues, but out of curiosity and the motivation to reduce the number of tools—since I heard mise also has direnv-like functionality—I decided to make the switch. My environment is macOS. ...

I created a GitHub Actions Reusable Workflows repository for my personal use. What Are GitHub Actions Reusable Workflows? GitHub Actions’ reusable workflows is a mechanism that allows workflow files to be called from other repositories. For example, you can call a workflow from another repository like this: jobs: example: uses: masutaka/actions/.github/workflows/some-workflow.yml@main Since you can consolidate common processes in one place, it saves you the trouble of managing the same workflow across multiple repositories. ...

The book I read this time is a new release by Daichi Hiroki @hiroki_daichi . I spotted it on Twitter and was curious enough to pick it up. AIエージェント 人類と協働する機械 amazon.co.jp It was a long read, but once Chapter 11 revealed the relationship between the SECI model and AI agents, things really heated up. ...

I spotted this on Twitter and read it over the year-end/New Year holidays. Claude CodeによるAI駆動開発入門 amazon.co.jp My vibe coding journey started with Cursor, but since around May of last year, I’ve been almost exclusively using Claude Code. Even writing this blog, I let Claude Code take it from zero to roughly 60% done. I’ve been keeping up with Claude Code by reading and trying out information that flows through Twitter and blog posts, in a mix of relaxation and a sense of urgency. ...

Last month I changed jobs and returned to Rails development after a long time. With a 6-year gap and only one month available for learning, I needed to efficiently grasp Rails 8’s new features and refresh my memory of existing ones. So I decided to learn by building a working app together with Claude Code while referencing the Rails Guides. I temporarily subscribed to Claude Code’s Max plan at USD 100/mo. ...