- Drain the eviction plan (pop + del) before trim_memory: the batch
thread previously held every evicted agent in its local list while
gc.collect + malloc_trim ran, so the in-pass trim freed almost
nothing, the next tick re-read a still-high RSS, and the valve
over-evicted an extra batch of warm prompt caches per cycle.
- Clear _db_flush_scan_prefix in _release_evicted_agent_soft: it is a
shallow copy of the flushed transcript (stamped on every successful
flush) sharing every message dict — and pressure-evictable agents
have flushed by definition, so it pinned the multi-MB content strings
on exactly the agents the valve targets.
- Config-read failure now falls back to resolve_agent_cache_bounds({})
instead of bare AgentCacheBounds(): the dataclass default disables
the pressure pass, but an absent config section means 'auto' — a
transient read failure must not permanently switch off the OOM valve.
- protect_recent: false (YAML bool; False == 0) keeps the default MRU
protection instead of silently disabling it.
- 'No evictable session' warning now distinguishes sessions blocked on
un-flushed persistence (e.g. session DB never initialized — NFS
HERMES_HOME) from mid-turn agents, so operators can diagnose why the
valve isn't shedding instead of being pointed at running turns.
- _cgroup_limit_bytes checks the process's own cgroup (via the existing
gateway.cgroup_cleanup._own_cgroup_path) before the root files, so a
systemd unit's MemoryHigh=/MemoryMax= is detected — the root
memory.high/max read 'max' on those deployments.
- Tests: 5 new guards; drain-before-trim and scan-prefix-clear
mutation-checked (revert each fix -> its guard fails).
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