A venv ever touched by sudo pip / sudo hermes contains root-owned files
(classically site-packages/*.dist-info/INSTALLER). A later normal-user
'hermes update' pulls code fine, then 'uv pip install -e .' dies with
'Permission denied (os error 13)' mid-mutation — venv/bin/hermes already
deleted, CLI bricked.
Add a bounded, pure-stat ownership preflight (_venv_foreign_owned_paths)
that runs after the code pull and immediately before the dependency
install. If foreign-owned paths are found it refuses up front, names the
offending paths + owner uid, prints the exact recovery command
(sudo chown -R $(id -un): <root>), and confirms the venv is untouched.
Windows (no os.geteuid) and root skip entirely. Never raises, capped at
~2000 stat calls, no subprocess use (update tests mock subprocess.run).
Same refuse-before-mutate philosophy as the contended-venv gate (#87331).
Fixes#83529
Diagnosis and documented recovery by @eabase.
Teknium