Follow-up to the two cherry-picked commits: use _run_in_executor_with_context
(the file's established off-loop helper — keeps the multiplex HERMES_HOME
override alive in the worker thread, same as the warm-up above) instead of a
bare run_in_executor(None, ...), drop the now-stale rationale that blamed
list_meta_prefix's writer lock (main reads via _read_ctx), and add a
regression test that holds the SessionDB writer lock from another thread
during one watcher scan and asserts the event loop keeps ticking. On main
the same test measures a 0.53 s loop stall for a 0.6 s hold.
kshitijk4poor
98428d20bc