The test patched sys.platform="linux" but called the cached
_get_isolation_strategy() — on macOS / Windows CI the cache had
already been populated with the host's strategy ("sandbox-exec" on
darwin, "best-effort" on win32) before the test ran, so the platform
patch was a no-op.
Use _compute_isolation_strategy() (uncached) like every other test in
the class. Also inject a fake os.unshare via monkeypatch so the
"namespaces" branch is reachable regardless of host kernel.
Tightened the assertion from `in {"namespaces", "best-effort"}` to
`== "namespaces"` since the unshare-unavailable case is covered by
the dedicated test_isolation_strategy_linux_unshare_unavailable test.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Closes#21, #22.
#21 RLVR code_exec_reward: add OS-level isolation strategy detection.
- New _get_isolation_strategy / _compute_isolation_strategy with cache.
- Linux: best-effort os.unshare(CLONE_NEWUSER|CLONE_NEWNET|CLONE_NEWPID)
in preexec_fn (Python 3.12+). Silent fallback on EPERM/ENOSYS for
hosts where unprivileged user namespaces are disabled.
- macOS: prefix subprocess argv with sandbox-exec + inline default-deny
profile (deny network*, deny writes outside /tmp).
- Windows + restricted Linux: existing RLIMIT + socket-patch + ephemeral
cwd guards continue to apply (best-effort baseline).
#22 prune_checkpoints: TOCTOU-safe symlink handling.
- Top-level entries: explicit os.lstat + stat.S_ISLNK check (intent-clear)
instead of Path.is_symlink.
- shutil.rmtree now passes onerror=_abort_on_symlink to abort recursive
walk if any symlink is encountered mid-walk (defence-in-depth).
- OSError mid-prune is caught per-checkpoint so one bad dir does not
abort the whole prune pass.
Tests: +13 in tests/test_part_f_hardening.py covering strategy detection
on linux/darwin/win32, sandbox profile shape, code_exec smoke tests, and
TOCTOU-resistant prune behaviour.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Alpamys