Simon Willison’s Weblog

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Wednesday, 3rd December 2025

TIL: Dependency groups and uv run. I wrote up the new pattern I'm using for my various Python project repos to make them as easy to hack on with uv as possible. The trick is to use a PEP 735 dependency group called dev, declared in pyproject.toml like this:

[dependency-groups]
dev = ["pytest"]

With that in place, running uv run pytest will automatically install that development dependency into a new virtual environment and use it to run your tests.

This means you can get started hacking on one of my projects (here datasette-extract) with just these steps:

git clone https://github.com/datasette/datasette-extract
cd datasette-extract
uv run pytest

I also split my uv TILs out into a separate folder. This meant I had to setup redirects for the old paths, so I had Claude Code help build me a new plugin called datasette-redirects and then apply it to my TIL site, including updating the build script to correctly track the creation date of files that had since been renamed.

# 5:55 am / packaging, python, ai, til, generative-ai, llms, ai-assisted-programming, uv, coding-agents, claude-code

Since the beginning of the project in 2023 and the private beta days of Ghostty, I've repeatedly expressed my intention that Ghostty legally become a non-profit. [...]

I want to squelch any possible concerns about a "rug pull". A non-profit structure provides enforceable assurances: the mission cannot be quietly changed, funds cannot be diverted to private benefit, and the project cannot be sold off or repurposed for commercial gain. The structure legally binds Ghostty to the public-benefit purpose it was created to serve. [...]

I believe infrastructure of this kind should be stewarded by a mission-driven, non-commercial entity that prioritizes public benefit over private profit. That structure increases trust, encourages adoption, and creates the conditions for Ghostty to grow into a widely used and impactful piece of open-source infrastructure.

Mitchell Hashimoto, Ghostty is now Non-Profit

# 7:18 pm / open-source, mitchell-hashimoto

2025 » December

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