Forensics on a live developer machine found pytest fixture rows inside the
REAL ~/.hermes/state.db — sessions with chat_id 'chat-1', '123', 'wx-chat',
and gateway_routing rows whose scope was literally under /tmp/pytest-of-*/.
A pytest-spawned process also opened the live DB and flipped its journal
mode (journal_mode=DELETE fallback on SQLite 3.50.4) under the WAL-mode
gateway writer, destroying committed transcripts ("Persisted transcript
lagged live cached history ... possible FTS write corruption", 15+
occurrences). The existing live-system guard covers kill primitives but not
the SessionDB/SessionStore write paths.
Root cause (leak vector): the session-level HERMES_HOME sandbox in
tests/conftest.py only created a tempdir when HERMES_HOME was UNSET. On a
machine where the shell (e.g. gateway-launched, or an exported
HERMES_HOME=~/.hermes) hands pytest the production home, the sandbox was
skipped entirely — every argless SessionDB()/SessionStore() and every
collection-time DEFAULT_DB_PATH froze onto the real state.db.
Fixes (fail the class, one owner):
* hermes_state._ensure_test_isolation(): single choke point wired into
SessionDB.__init__ (every construction, incl. read_only). Under pytest
(PYTEST_CURRENT_TEST / PYTEST_VERSION — inherited by subprocess
children), a db path resolving to <real-root>/state.db or
<real-root>/profiles/<name>/state.db raises RuntimeError('live-system
guard: ...') before any connection, mkdir, or journal-mode pragma.
* tests/conftest.py: session sandbox now also tempdir-redirects a pre-set
HERMES_HOME that points at the production root (the actual escape
vector); kanban deny-list capture updated to match. New autouse
_state_db_write_guard fixture honors the existing
@pytest.mark.live_system_guard_bypass marker as the escape hatch and
feeds custom (non-~/.hermes) production roots into the guard deny-list.
* gateway/session.py: SessionStore.__init__ no longer swallows the guard's
RuntimeError into the JSONL fallback — guard trips are loud.
* tests/hermes_state/test_live_db_isolation_guard.py: behavioral
regression tests — production paths (direct, profile, read-only,
unnormalized, default-resolution) raise; tmp HERMES_HOME works; bypass
marker works; SessionStore re-raises guard errors but still degrades on
ordinary failures; subprocess child without HERMES_HOME is refused while
a hermetic child succeeds.
No new HERMES_* env vars; no hardcoded ~/.hermes (platform root comes from
hermes_constants._get_platform_default_hermes_home()).
19fc9c103e