SessionStore.prune_old_entries was calling
self._has_active_processes_fn(entry.session_id) but the callback wired
up in gateway/run.py is process_registry.has_active_for_session, which
compares against session_key, not session_id. Every other caller in
session.py (_is_session_expired, _should_reset) already passes
session_key, so prune was the only outlier — and because session_id and
session_key live in different namespaces, the guard never fired.
Result in production: sessions with live background processes (queued
cron output, detached agents, long-running Bash) were pruned out of
_entries despite the docstring promising they'd be preserved. When the
process finished and tried to deliver output, the session_key to
session_id mapping was gone and the work was effectively orphaned.
Also update the existing test_prune_skips_entries_with_active_processes,
which was checking the wrong interface (its mock callback took session_id
so it agreed with the buggy implementation). The test now uses a
session_key-based mock, matching the production callback's real contract,
and a new regression guard test pins the behaviour.
Swallowed exceptions inside the prune loop now log at debug level instead
of silently disappearing.
6b408e131c