It's common to not use virtual environments in containers, e.g. see discussion around PEP 704. I don't mind the default being to prevent installation into a base environment, but it would be nice to have some low level flag to override it.

error: Failed to locate a virtualenv or Conda environment (checked: `VIRTUAL_ENV`, `CONDA_PREFIX`, and `.venv`). Run `uv venv` to create a virtualenv.

(Maybe I can lie about VIRTUAL_ENV to work around...)