Direnv is All You Need to Parallelize Agentic Programming with Git Worktrees

I've known for months that Git worktrees are essential for running AI coding agents like Claude Code and Codex in parallel. However, my early attempts to integrate them into my workflow failed multiple times. The problem wasn't Git itself-creating a worktree and a new branch via the CLI or Magit is trivial. The real obstacle lies in the .gitignore'd parts of your project. Things like .env files containing environment variables, or your Python .venv directory, don't carry over to new directories. Naively creating a Git worktree results in an incomplete environment, causing agentic tools to fail when trying to run standard development commands like linting, compiling, or testing. ...

March 13, 2026 · Walden Cui

How To Remove Background of A Photo Using GIMP

First import the photo: File -> Open. Select "Fuzzy Select Tool": Shift + u. On the left, select "Antialiasing", "Feather edges" and "Draw mask". Click on the background of the photo. Hold the click and drag downward to increase the threshold and upward to decrease the threshold, so that you can select more or less. Once you are good with the selection, let go of the selection by clicking on DEL on your keyboard. Repeat this process a few times until it's satisfactory.

January 5, 2026 · Walden Cui

Lower Level Abstractions For Web Developers

You should know your layer well, but you should also know one layer below it a little bit, and you definitely need to know the shape of the layer that’s beneath that. – Godbolt’s rule by Corecursive Edit: Later on I realized it's the same Goldbolt who created a compiler explorer. Full stack web developers are sitting upon layers of abstractions and can often get lost due to the lack of understanding of the layers below. Understanding these "layers below" is what separates a developer who uses a framework from a developer who understands how web applications work. ...

November 9, 2025 · Walden Cui

Simplicity vs complexity

Two articles about software design pop up on HN: Do the simplest thing that could possibly work Cognitive load is what matters Design is about dealing with complexity. You start with a problem and then you want to solve the problem. There can be numerous ways but often the best way is the simplest way. Now in a craft like software design, it's usually not that easy to be simple and often it requires years of experience for one to reach that point. But sticking to the fundamentals and avoiding shiny techniques can go a long way: ...

August 30, 2025 · Walden Cui