- state_db fixture: drop the HERMES_HOME setenv + sys.modules purge
(SessionDB takes an explicit path; tests/conftest.py already sandboxes
HERMES_HOME; the purge risks split-class identity for other modules
holding the old hermes_state reference) — matches the plain
tests/hermes_state/ sibling fixture pattern.
- probe guard asserts on the CALL ('has_archived_messages(') instead of a
local-variable name — a reintroduced probe under any rename now trips
it (mutation-checked: renamed-probe reintroduction fails the guard;
restored stack green).
- _archived_count uses the public get_messages(include_inactive=True)
instead of poking db._lock/_conn.
a82910c37b