Show current awareness: "I use Poetry for application projects because it handles lockfiles and virtual environments together. For libraries, I use pyproject.toml with Hatch for PEP 621 compliance."
Virtual environments isolate project dependencies. Tools: venv (built-in), pip + requirements.txt (basic), pip-tools (compiled lockfiles), Poetry (dependency resolution + packaging), PDM or Hatch (modern PEP 621). Strong candidates discuss: lockfiles for reproducibility, separating dev/prod dependencies, dependency resolution conflicts, and publishing packages. They should know about pyproject.toml as the modern config standard.
Baseline Python ecosystem knowledge. Candidates who manually manage requirements.txt without lockfiles will cause "works on my machine" problems. Those who know modern tooling (Poetry, PDM, uv) are up to date.