HA 2026.5 enforces strict validation of device_class/unit_of_measurement
pairs in MQTT discovery payloads. Four categories were broken:
- power_factor: unit was sent as "power_factor" (the FIMP field name); HA
requires the field to be omitted or empty for this device class. Fixed by
normalising the display unit separately from the FIMP data-path key.
- illuminance: unit "Lux" is rejected; normalise to "lx". When a sensor
reports luminance as "%" (some Z-Wave devices), the illuminance device
class is dropped so the entity becomes a generic sensor rather than
triggering a validation error.
- reactive_power (regular/export meter): unit "VAr" is rejected; HA requires
lowercase "var".
- reactive_power (extended meter values, e.g. p_import_react): the unit
determination logic fell through to the generic power branch and sent "W";
reactive power extended values now emit "var", apparent power values emit
"VA", and reactive energy values emit "kvarh".
Fixes#31
Co-authored-by: Claude <noreply@anthropic.com>
