The documentation for uv says:
If your project does not include a [build-system] definition in the pyproject.toml, uv will not build it by default.
However:
C:\Users\USERNAME\Downloads>uv init hello-world
Initialized project `hello-world` at `C:\Users\USERNAME\Downloads\hello-world`
C:\Users\USERNAME\Downloads>cd hello-world
C:\Users\USERNAME\Downloads\hello-world>cat pyproject.toml
[project]
name = "hello-world"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.13"
dependencies = []
C:\Users\USERNAME\Downloads\hello-world>uv build
Building source distribution...
running egg_info
creating hello_world.egg-info
writing hello_world.egg-info\PKG-INFO
writing dependency_links to hello_world.egg-info\dependency_links.txt
writing top-level names to hello_world.egg-info\top_level.txt
writing manifest file 'hello_world.egg-info\SOURCES.txt'
reading manifest file 'hello_world.egg-info\SOURCES.txt'
writing manifest file 'hello_world.egg-info\SOURCES.txt'
running sdist
running egg_info
writing hello_world.egg-info\PKG-INFO
writing dependency_links to hello_world.egg-info\dependency_links.txt
writing top-level names to hello_world.egg-info\top_level.txt
reading manifest file 'hello_world.egg-info\SOURCES.txt'
writing manifest file 'hello_world.egg-info\SOURCES.txt'
running check
creating hello_world-0.1.0
creating hello_world-0.1.0\hello_world.egg-info
copying files to hello_world-0.1.0...
copying README.md -> hello_world-0.1.0
copying main.py -> hello_world-0.1.0
copying pyproject.toml -> hello_world-0.1.0
copying hello_world.egg-info\PKG-INFO -> hello_world-0.1.0\hello_world.egg-info
copying hello_world.egg-info\SOURCES.txt -> hello_world-0.1.0\hello_world.egg-info
copying hello_world.egg-info\dependency_links.txt -> hello_world-0.1.0\hello_world.egg-info
copying hello_world.egg-info\top_level.txt -> hello_world-0.1.0\hello_world.egg-info
copying hello_world.egg-info\SOURCES.txt -> hello_world-0.1.0\hello_world.egg-info
Writing hello_world-0.1.0\setup.cfg
Creating tar archive
removing 'hello_world-0.1.0' (and everything under it)
Building wheel from source distribution...
running egg_info
writing hello_world.egg-info\PKG-INFO
writing dependency_links to hello_world.egg-info\dependency_links.txt
writing top-level names to hello_world.egg-info\top_level.txt
reading manifest file 'hello_world.egg-info\SOURCES.txt'
writing manifest file 'hello_world.egg-info\SOURCES.txt'
running bdist_wheel
running build
running build_py
creating build\lib
copying main.py -> build\lib
running egg_info
writing hello_world.egg-info\PKG-INFO
writing dependency_links to hello_world.egg-info\dependency_links.txt
writing top-level names to hello_world.egg-info\top_level.txt
reading manifest file 'hello_world.egg-info\SOURCES.txt'
writing manifest file 'hello_world.egg-info\SOURCES.txt'
installing to build\bdist.win-amd64\wheel
running install
running install_lib
creating build\bdist.win-amd64\wheel
copying build\lib\main.py -> build\bdist.win-amd64\wheel\.
running install_egg_info
Copying hello_world.egg-info to build\bdist.win-amd64\wheel\.\hello_world-0.1.0-py3.13.egg-info
running install_scripts
creating build\bdist.win-amd64\wheel\hello_world-0.1.0.dist-info\WHEEL
creating 'C:\Users\USERNAME\Downloads\hello-world\dist\.tmp-9cxdd7r9\hello_world-0.1.0-py3-none-any.whl' and adding 'build\bdist.win-amd64\wheel' to it
adding 'main.py'
adding 'hello_world-0.1.0.dist-info/METADATA'
adding 'hello_world-0.1.0.dist-info/WHEEL'
adding 'hello_world-0.1.0.dist-info/top_level.txt'
adding 'hello_world-0.1.0.dist-info/RECORD'
removing build\bdist.win-amd64\wheel
Successfully built dist\hello_world-0.1.0.tar.gz
Successfully built dist\hello_world-0.1.0-py3-none-any.whl
Am I missing something or is it building a project that does not include a [build-system] definition in the pyproject.toml?
uv buildfor publishing, not building for a local install. If you find the language of this section confusing, please open a documentation issue inuvrepo.