When a virtual environment is created, the resulting pyvenv.cfg specifies the directory which contained the Python executable and the version of Python (see https://github.com/python/cpython/blob/master/Lib/venv/__init__.py#L147). Unfortunately that may not be enough to work backwards to which binary was used to create the virtual environment.

My idea is to add an `executable` and `command` key to pyvenv.cfg which record the Python executable name and the command used to construct the virtual environment, respectively. The former would disambiguate which exact Python interpreter was used, and the `command` key could be used by e.g. virtualenv to record what was used to construct the virtual environment. That potentially could be used to make recreating a broken virtual environment easier.