activity_log only ever recorded state transitions/overrides/sync/errors —
useful for "what did the app decide" but not "what was the room actually
doing" when a guest/staff complaint comes in after the fact.
Backend:
- New device_readings time-series table (room_temp, target_temp, mode,
power_state, fan_speed, valve_position, heating_active), throttled to
~1 row/device/minute via recordReading() in db.js regardless of how
often a caller fires — MQTT pushes can be far chattier than that.
- Wired into every place zone_devices' live-status cache already gets
updated: ac-poller.js, daikin-poller.js, and mqtt.js's TRV
(handleStatusBlob/handleInfo) and native-MQTT MHI (writeMhiState)
handlers.
- 4-day retention by default (config key history_retention_days),
pruned every 6h by the new history-pruner.js.
- GET /api/devices/:id/history?hours=96 to read it back.
Frontend:
- DeviceHistoryModal: room temp vs setpoint line chart, plus a
valve-position chart (TRVs) or fan-speed step chart (AC), plus a
diffed mode/power/fan change log — 24h/4d/7d range picker. Uses
recharts, matching the convention already established in
utilities/wages/reports.
- Graph icon on each device in both ZoneDetailModal and the Devices
page opens it.
Side effect: frontend/package-lock.json was missing vite-plugin-pwa's
whole dependency tree even though package.json already declared it —
pre-existing drift, reconciled by this npm install (unrelated to the
recharts addition, just came along with it).