Python virtual environments (python -m venv) are not magic: they are a specific directory layout plus pyvenv.cfg that controls where Python imports and where pip installs. When installs land in the “wrong” place or imports behave inconsistently, the evidence is inside .venv/. This guide maps each folder and file (Scripts/bin, site-packages, .dist-info, pyvenv.cfg) to the behavior it drives, so you