A collection of concise write-ups on small things I learn day to day across a variety of languages and technologies. (more)
Jan 31, 2026
What I Learned I built a system that balances screen production at the venue with streaming and archive recording at the event site. By physically separating yet network-integrating the different requirements of “never stopping venue progression” (Main System) and “creating high-quality archives” (Sub System), both could be achieved simultaneously. By incorporating long-distance transmission via SDI and one-button control with Bitfocus Companion, the system became robust with minimal chance of operator errors even with a small team.
Nov 30, 2025
What I Learned Sensitive information (API keys, private keys, configuration files, etc.) that has been accidentally committed continues to remain in Git’s history even with normal deletion. By using git filter-repo, you can rewrite Git history and completely remove sensitive information. However, removing from history does not make already leaked credentials safe, so you must always revoke and reissue the relevant credentials.
Details Background Previously, methods using git filter-branch were introduced, but warnings are now issued in the official documentation, and when creating new procedures, the use of git filter-repo is recommended.
Nov 29, 2025
What I Learned When sharing URLs with others, query parameters and fragments can make URLs long and include unnecessary information. I used to manually delete them, but by combining a bookmarklet with Chrome’s search engine feature, I can now clean URLs using only keyboard shortcuts.
Details Background While browsing the web, URLs often have parameters like ?utm_source=... or #section. There are many situations where you want to remove these and have a simple URL, but manually deleting them is tedious.
Nov 28, 2025
What I Learned I organized a workflow for using Git solely locally, without using remotes like GitHub, aimed at Git beginners and individual developers. Since Git inherently keeps all history locally, understanding local Git before learning about remotes makes it easier to handle and less confusing. Backups (pseudo-remote/mirror) are possible even within local environments.
Details Benefits of Using Git Locally Only Fewer concepts to learn, easier to study No risk of bothering others Can focus on Git’s essence (managing change history) 1.
Nov 27, 2025
What I Learned I usually develop on a Mac, but recently I’ve had more opportunities to teach development to Windows users. So I organized the procedure for setting up a development environment on Windows. With the combination of WSL2 + Ubuntu + Git + VS Code, you can build a comfortable Linux development environment on Windows similar to Mac. It’s lighter than virtual machines and file sharing with Windows is smooth.
Nov 19, 2025
What I Learned I learned how to remove unwanted file changes from a specific commit in a Pull Request. By combining git rebase -i and git commit --amend, you can pinpoint and modify past commits while keeping the history clean.
Details The Problem When creating a PR and checking the diff, I found that a certain commit had unintentionally changed a file:
D example/config.yaml (deleted) It’s common to accidentally include unrelated changes such as configuration files or documentation in commits.
Nov 10, 2025
What I Learned I developed “Hirameki Mixer,” an AI invention generation app for a university festival exhibition. It’s an interactive web application that combines two keywords to generate new invention ideas (product name, tagline, and image) using AI. By utilizing Claude Code, I was able to complete the development in about one day.
Details Project Overview From two keywords, it automatically generates new invention ideas using Google Vertex AI. The generated inventions can be viewed in a 3D space gallery.
Nov 5, 2025
What I Learned Git’s interactive rebase (git rebase -i) is a powerful tool for cleaning up commit history before pushing changes. It allows you to reorder, squash, edit, or remove commits.
Details Interactive rebase opens an editor with a list of commits and commands:
1git rebase -i HEAD~3 Available commands:
pick - use commit as-is reword - change commit message edit - stop for amending squash - combine with previous commit fixup - like squash but discard commit message drop - remove commit Example workflow:
Nov 5, 2025
What I Learned Hugo archetypes are template files that help you quickly create new content with pre-defined front matter and structure. They save time and ensure consistency across your content.
Details Archetypes in Hugo work like blueprints for your content. When you run hugo new, Hugo looks for an archetype file matching your content type and uses it as a template.
For example, with our TIL archetype at archetypes/til.md:
1hugo new content/tils/my-new-til.