- Introduce tests/e2e/test_nix_build_pkgmgr.py to inspect the Nix environment and build the pkgmgr flake inside the container started by test-e2e.sh - Run the same commands in every distro container: nix --version, sandbox config, id, and nix build .#pkgmgr -L - Print stdout/stderr and assert the flake build succeeds for easier cross-distro Nix debugging https://chatgpt.com/share/693aa33f-4e3c-800f-86ec-99c38a07eacb