The hermetic conftest now exports HERMES_TEST_ISOLATION (value = the tmp
isolation root) before any test module imports, and re-pins it per test in
_hermetic_environment. hermes_state._running_under_pytest() honors the
marker as a test-context signal alongside PYTEST_CURRENT_TEST /
PYTEST_VERSION.
Why a third layer: PYTEST_* belongs to pytest, and tests that spawn
children routinely rebuild the child env and strip it ("the subprocess
must look like a real CLI" — tests/cli/test_exit_watchdog_signal_arm.py,
tests/hermes_cli/test_config_loader_e2e.py do exactly this on purpose).
Such a child loses the HERMES_HOME redirect and the guard's arming signal
in one step, which is how 700+ zero-message fixture rows (dm:123, chat-1,
wx-chat, ...) landed in a developer's production state.db. The marker is
OURS: stripping it is never required to make a child "look real" (no
production code branches on it except the guard), it inherits by default,
and children that genuinely need a real DB use the sanctioned
HERMES_STATE_DB_GUARD_BYPASS=1 hatch instead.
The ancestry-walk layer (previous commits) stays: it covers children whose
env was rebuilt from a completely empty dict. The marker layer covers the
common **os.environ-derived rebuilds cheaply (one dict lookup, no psutil),
and — unlike ancestry — also covers detached/daemonized children that
escape the process tree.
tests/hermes_state/test_isolation_marker_env.py pins: the conftest export,
the marker-alone arming, the rebuilt-env child refusing the production
path, and the bypass hatch. Sabotage-verified: 3/6 fail without the fix.
test_live_db_guard_ancestry._scrubbed_env now strips the marker too, so
the ancestry tests keep proving ancestry rather than riding the marker.
Teknium