uv is not available as package when using uv-venv-lock-runner

[leon1995]

Issue

When configuring the runner as "uv-venv-lock-runner" in pyproject.toml, then uv is not available as package

[tool.tox] 
env_list = ["py311", "py312", "py313"]

[tool.tox.env_run_base]
runner = "uv-venv-lock-runner"
package = "uv"
commands = [["pytest"]]
dependency_groups = ["test"]

Is this intended?

Environment

Provide at least:

• OS: windows

Output of pip list of the host Python, where tox is installed

Output of running tox

Output of tox -rvv

py311: 667 W remove tox env folder C:\project\path\.tox\py311 [tox\tox_env\api.py:332]
py311: 905 W venv> C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\uv.exe venv -p C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\python.exe --allow-existing -v --python-preference system C:\project\path\.tox\py311 [tox\tox_env\api.py:434]
DEBUG uv 0.6.3 (a0b9f22a2 2025-02-24)
DEBUG Found project root: `C:\project\path`
DEBUG No workspace root found, using project root
DEBUG Using Python request `C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\python.exe` from explicit request
DEBUG Checking for Python interpreter at path `C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\python.exe`
Using CPython 3.11.6 interpreter at: C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\python.exe
Creating virtual environment at: .tox\py311
DEBUG Using base executable for virtual environment: C:\Users\<redacted>\AppData\Roaming\uv\python\cpython-3.11.6-windows-x86_64-none\python.exe
DEBUG Allowing existing directory
Activate with: .tox\py311\Scripts\activate
py311: 1549 I exit 0 (0.64 seconds) C:\project\path> C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\uv.exe venv -p C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\python.exe --allow-existing -v --python-preference system C:\project\path\.tox\py311 pid=31552 [tox\execute\api.py:294]
py311: 1550 E internal error [tox\session\cmd\run\single.py:60]
Traceback (most recent call last):
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\session\cmd\run\single.py", line 47, in _evaluate
    tox_env.setup()
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\tox_env\api.py", line 257, in setup
    self._setup_env()
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox_uv\_run_lock.py", line 90, in _setup_env
    package = self.conf["package"]
              ~~~~~~~~~^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\sets.py", line 122, in __getitem__
    return self.load(item)
           ^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\sets.py", line 133, in load
    return config_definition.__call__(self._conf, self.loaders, ConfigLoadArgs(chain, self.name, self.env_name))  # noqa: PLC2801
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\of_type.py", line 109, in __call__
    value = loader.load(key, self.of_type, self.factory, conf, args)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\api.py", line 148, in load
    converted = self.build(key, of_type, factory, conf, raw, args)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\toml\__init__.py", line 66, in build
    return self.to(exploded, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\convert.py", line 33, in to
    return self._to_typing(raw, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\convert.py", line 87, in _to_typing
    raise ValueError(msg)
ValueError: uv must be one of ('editable', 'wheel', 'skip')
py311: FAIL ✖ in 0.97 seconds
py312: 1644 W remove tox env folder C:\project\path\.tox\py312 [tox\tox_env\api.py:332]
py312: 1884 W venv> C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\uv.exe venv -p cpython3.12 --allow-existing -v --python-preference system C:\project\path\.tox\py312 [tox\tox_env\api.py:434]
DEBUG uv 0.6.3 (a0b9f22a2 2025-02-24)
DEBUG Found project root: `C:\project\path`
DEBUG No workspace root found, using project root
DEBUG Using Python request `cpython@3.12` from explicit request
DEBUG Searching for CPython 3.12 in managed installations, search path, or registry
DEBUG Found `cpython-3.11.6-windows-x86_64-none` at `C:\project\path\.venv/Scripts\python.exe` (first executable in the search path)
DEBUG Ignoring Python interpreter at `C:\project\path\.venv\Scripts\python.exe`: system interpreter required
DEBUG `LOCALAPPDATA` not set, ignoring Microsoft store Pythons
DEBUG Found `cpython-3.12.3-windows-x86_64-none` at `C:\Users\<redacted>\AppData\Local\Programs\Python\Python312\python.exe` (registry)
Using CPython 3.12.3 interpreter at: C:\Users\<redacted>\AppData\Local\Programs\Python\Python312\python.exe
Creating virtual environment at: .tox\py312
DEBUG Using base executable for virtual environment: C:\Users\<redacted>\AppData\Local\Programs\Python\Python312\python.exe
DEBUG Allowing existing directory
Activate with: .tox\py312\Scripts\activate
py312: 1987 I exit 0 (0.09 seconds) C:\project\path> C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\uv.exe venv -p cpython3.12 --allow-existing -v --python-preference system C:\project\path\.tox\py312 pid=29784 [tox\execute\api.py:294]
py312: 1990 E internal error [tox\session\cmd\run\single.py:60]
Traceback (most recent call last):
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\session\cmd\run\single.py", line 47, in _evaluate
    tox_env.setup()
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\tox_env\api.py", line 257, in setup
    self._setup_env()
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox_uv\_run_lock.py", line 90, in _setup_env
    package = self.conf["package"]
              ~~~~~~~~~^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\sets.py", line 122, in __getitem__
    return self.load(item)
           ^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\sets.py", line 133, in load
    return config_definition.__call__(self._conf, self.loaders, ConfigLoadArgs(chain, self.name, self.env_name))  # noqa: PLC2801
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\of_type.py", line 109, in __call__
    value = loader.load(key, self.of_type, self.factory, conf, args)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\api.py", line 148, in load
    converted = self.build(key, of_type, factory, conf, raw, args)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\toml\__init__.py", line 66, in build
    return self.to(exploded, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\convert.py", line 33, in to
    return self._to_typing(raw, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\convert.py", line 87, in _to_typing
    raise ValueError(msg)
ValueError: uv must be one of ('editable', 'wheel', 'skip')
py312: FAIL ✖ in 0.36 seconds
py313: 1994 W remove tox env folder C:\project\path\.tox\py313 [tox\tox_env\api.py:332]
py313: 2258 W venv> C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\uv.exe venv -p cpython3.13 --allow-existing -v --python-preference system C:\project\path\.tox\py313 [tox\tox_env\api.py:434]
DEBUG uv 0.6.3 (a0b9f22a2 2025-02-24)
DEBUG Found project root: `C:\project\path`
DEBUG No workspace root found, using project root
DEBUG Using Python request `cpython@3.13` from explicit request
DEBUG Searching for CPython 3.13 in managed installations, search path, or registry
DEBUG Found `cpython-3.11.6-windows-x86_64-none` at `C:\project\path\.venv/Scripts\python.exe` (first executable in the search path)
DEBUG Ignoring Python interpreter at `C:\project\path\.venv\Scripts\python.exe`: system interpreter required
DEBUG `LOCALAPPDATA` not set, ignoring Microsoft store Pythons
DEBUG Searching for managed installations at `C:\Users\<redacted>\AppData\Roaming\uv\python`
DEBUG Skipping incompatible managed installation `cpython-3.14.0a5-windows-x86_64-none`
DEBUG Found managed installation `cpython-3.13.2-windows-x86_64-none`
DEBUG Found `cpython-3.13.2-windows-x86_64-none` at `C:\Users\<redacted>\AppData\Roaming\uv\python\cpython-3.13.2-windows-x86_64-none\python.exe` (managed installations)
Using CPython 3.13.2
Creating virtual environment at: .tox\py313
DEBUG Using base executable for virtual environment: C:\Users\<redacted>\AppData\Roaming\uv\python\cpython-3.13.2-windows-x86_64-none\python.exe
DEBUG Allowing existing directory
Activate with: .tox\py313\Scripts\activate
py313: 2394 I exit 0 (0.12 seconds) C:\project\path> C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Scripts\uv.exe venv -p cpython3.13 --allow-existing -v --python-preference system C:\project\path\.tox\py313 pid=31252 [tox\execute\api.py:294]
py313: 2396 E internal error [tox\session\cmd\run\single.py:60]
Traceback (most recent call last):
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\session\cmd\run\single.py", line 47, in _evaluate
    tox_env.setup()
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\tox_env\api.py", line 257, in setup
    self._setup_env()
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox_uv\_run_lock.py", line 90, in _setup_env
    package = self.conf["package"]
              ~~~~~~~~~^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\sets.py", line 122, in __getitem__
    return self.load(item)
           ^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\sets.py", line 133, in load
    return config_definition.__call__(self._conf, self.loaders, ConfigLoadArgs(chain, self.name, self.env_name))  # noqa: PLC2801
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\of_type.py", line 109, in __call__
    value = loader.load(key, self.of_type, self.factory, conf, args)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\api.py", line 148, in load
    converted = self.build(key, of_type, factory, conf, raw, args)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\toml\__init__.py", line 66, in build
    return self.to(exploded, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\convert.py", line 33, in to
    return self._to_typing(raw, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\<redacted>\AppData\Roaming\uv\tools\tox\Lib\site-packages\tox\config\loader\convert.py", line 87, in _to_typing
    raise ValueError(msg)
ValueError: uv must be one of ('editable', 'wheel', 'skip')
  py311: FAIL code 2 (0.97 seconds)
  py312: FAIL code 2 (0.36 seconds)
  py313: FAIL code 2 (0.41 seconds)
  evaluation failed :( (1.95 seconds)

Minimal example

[gaborbernat]

FWIW this is a bug. It should not crash. That being said with uv-venv-lock-runner we do no packaging, so while this should not crash any value would be effectively ignored as we implicitly always use uv packaging for such cases.