Opus SHIP-WITH-FIXES (no code change required): the comment/docstring overstated
that the session-list-change listener covers ALL structural mutations. In-app
mutations fire it, but externally-driven changes (scheduled cron completion,
external CLI writes) don't — for those the 30s streaming TTL is the load-bearing
backstop (≤30s bounded, self-healing lag). Comment-only accuracy fix; logic
unchanged (both gates: perf fix correct, freeze effective, staleness bounded).