My initial reaction is that adding an argument for this feels unnecessary. It’s almost as much work to provide the argument as it is to rename the file. I’m gonna defer to @zanieb on this one though.

Fair point. I think my preference here would actually be making uv init generate main.py over hello.py. Should have made that my request! For now, I've implemented this manually in my .zshrc with:

uvi() {
    uv init "$@"
    mv hello.py main.py
}

#7670 is similar but not the same, about picking more commonly preferred defaults

I think we could call it main.py instead — though having a function main in a file main and also having a __main__ file in some cases could be confusing. I'm not attached to the default name of hello.py though. It was mostly intended to be an example file that matched the other init kinds which have a hello command and function.

If it helps as a data-point: From the research I did for the Heroku Python buildpacks [1] (using metrics from many thousands of builds/apps), the most common filenames we see in "single .py file in the root directory" type projects are app.py and main.py. The latter I'm guessing due to guides like the FastAPI tutorial using main.py. The former I'm less certain about, but I know Flask does auto-detection if it finds an app.py - so perhaps that's the reason?

[1]: One of the features of Heroku is that users can git push arbitrary code to their app, and the Heroku build system via the buildpack detection feature will determine which language their app uses, and run the appropriate buildpack to build that app. Whilst the primary signal our Python buildpack checks for is the presence of a package manager file (such as requirements.txt, poetry.lock, and in the future uv.lock etc), it's not uncommon for users to have manually pip installed their dependencies locally and either not created a requirements file at all, or forgotten to Git commit it. So we use additional signals to determine the app's primary language is likely Python (bearing in mind apps can be multi-language, and users can have one-off Python scripts in the repo root that are for development use only), so we can then display a "the package manager file is missing" type error to those apps.