Devtools must be open source

There's a quiet shift happening in how software gets shaped to fit the people using it, and it has nothing to do with plugins or config files anymore. A blog post making the rounds this week, written by someone building the Shelley coding agent, argues that AI coding agents have completely changed the math on personalizing your own tools. Five years ago, almost no engineer bothered writing software just for themselves — it took too long, and maintaining it a year later was miserable. Now a single prompt can fork a tool, rewire its behavior, and set up a nightly cron job that rebases your custom changes on top of upstream releases automatically.

The author walks through a real example: a side project called meat.dev, a tool that uses an LLM to strip boring boilerplate — nil-checks, import blocks, error handling — out of code diffs so a human reviewer only sees the parts that actually matter architecturally. Wiring that into Shelley's UI, instead of running it from a terminal, took one prompt telling the agent to install it, hook it into commit creation, and add a toggle to the diff view. The agent did it in one shot. It even added a little steak emoji to the button, unprompted, which the author notes would've been a nightmare to pull off through something like the VS Code extension API.

That's the real argument buried in the post: plugin systems and config files existed because customizing code used to be expensive, so companies amortized that cost across thousands of users. Vim's core is huge and baroque because building in an extension system was the only sane way to let people add line numbers without reading the whole codebase. Agents blow that economics up. If a top-tier model can implement a single-user feature in one shot, and