Backend:
- Session.last_subscriber_left_at: monotonic timestamp set when last SSE subscriber
leaves, cleared when a new one arrives
- Session.subscriber_count(): replaces len(_subscribers) access from outside the model
- session_store._reaper_loop(): kills sessions with no subscribers for >SESSION_IDLE_TTL_S
(default 90s); runs every TTL/2 seconds via asyncio.create_task at startup
- session_store._reaper_loop_once(): single-cycle variant for deterministic tests
- app/main.py lifespan: starts reaper on startup, cancels it cleanly on shutdown
- config.py: SESSION_IDLE_TTL_S setting (90s default, overridable per-env)
Frontend:
- useWakeLock.ts: Screen Wake Lock API wrapper; acquires on connect, releases on
disconnect; degrades silently when unsupported (battery saver, iOS Safari)
- useToneStream.ts: visibilitychange handler — on hidden: closes EventSource without
ending backend session (grace window stays open); on visible: GET /session/{id}
liveness check, reconnects SSE + re-acquires wake lock if alive, sets expired=true
and calls store.reset() if reaped
- ComposeBar.vue: surfaces expired state with calm 'Session timed out' notice
(not an error — expected behaviour on long screen-off)
Tests:
- test_reaper.py: 7 tests covering subscriber idle tracking, reaper eligibility
(kills idle, spares active subscriber, spares within-TTL)
