Fix spurious energy resets on ZEN20/ZEN25 power strips

[electricessence]

The ZEN20 (and ZEN25) periodically resets its energy (kWh) counters to zero without user action — sometimes as often as once a day. This affects the parent device and all child endpoints (5 plugs, 2 USB). Because the reset only affects the energy value and not the duration, it's clearly a device firmware issue rather than a legitimate reset. With 4+ power strips (24+ devices), correcting this downstream is not feasible.

Solution

Added monotonic energy tracking that absorbs spurious resets. The reported energy attribute is now always energyBase + deviceReportedValue, where energyBase is the cumulative sum of negative deltas from the device.

• When the device-reported energy drops (e.g., 5.2 → 0), the lost amount is added to energyBase
• The emitted energy value continues to climb as expected
• Clicking Reset Stats clears energyBase for the parent and all children, so user-initiated resets work normally

Implementation

Two small helper functions that operate on any device object (parent or child):

• trackEnergy(dev, value) — reads/writes energyBase and energyLastReported via getDataValue/updateDataValue, returns the corrected energy value
• resetEnergyTracking(dev) — removes both data values from the device

Using updateDataValue/getDataValue (instead of state) because:

• Works uniformly on parent and child devices from the parent driver
• Survives state.clear() — no backup/restore needed in clearVariables
• Values visible in the "Data" section of each device page for debugging

Edge case: If a stale MeterReport is in-flight when Reset Stats is clicked, it could briefly re-establish a energyLastReported that triggers false drop detection on the next real report. This window is extremely narrow (report intervals are 30-60+ seconds) and self-corrects by clicking Reset Stats again.

[electricessence]

@jtp10181 I'm currently testing this fix on my Hubitat now.
It will take a day or two to see if the issue is fixed.
I'll report back in a couple days.

[Copilot]

Pull request overview

Adds monotonic energy (kWh) reporting for Zooz ZEN20/ZEN25 multi-channel plug/strip devices by tracking and compensating for device-reported energy counter resets using per-device data values (parent + child endpoints).

Changes:

• Add energy tracking via energyBase + energyLastReported stored in device data values to absorb negative deltas.
• Update energy event emission to publish corrected (monotonic) energy values for parent and child endpoints.
• Clear energy tracking data for parent and all children when Reset Stats is invoked.

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[electricessence]

@jtp10181 I've been testing this for days. It's working great. Only affects energy totals and works perfectly with child devices.
LGTM!