Use Radon device class in Airthings BLE

[abmantis]

Proposed change

Replace the custom unit logic with the recently added radon device class.

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[home-assistant]

Hey there @vincegio, @LaStrada, mind taking a look at this pull request as it has been labeled with an integration (airthings_ble) you are listed as a code owner for? Thanks!

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[Copilot]

Pull request overview

This PR updates the Airthings BLE integration to model radon measurements using Home Assistant’s radon sensor device class and standard radon concentration units, removing bespoke unit-handling code in the integration.

Changes:

• Switch radon average sensors to SensorDeviceClass.RADON with UnitOfRadiationConcentration.BECQUEREL_PER_CUBIC_METER.
• Remove custom radon unit constants and the per-unit-system unit swapping logic in sensor setup.
• Force the underlying library fetch to use metric radon values so Home Assistant can perform consistent unit conversion for display.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
homeassistant/components/airthings_ble/sensor.py	Uses radon device class + standard unit enum and removes custom unit-mapping logic.
homeassistant/components/airthings_ble/icons.json	Removes explicit icon overrides for radon average sensors (now covered by device class behavior).
homeassistant/components/airthings_ble/coordinator.py	Always requests metric values from the library to support HA-managed unit conversion.
homeassistant/components/airthings_ble/const.py	Removes custom radon unit string constants no longer needed.

[jpettitt]

overall LGTM - minor non-blocking suggestions

[SUGGESTION] tests/components/airthings_ble/test_sensor.py — no test asserts the new behavior. A small test verifying the radon sensors report device_class: radon with Bq/m³ native unit (and ideally one with US_CUSTOMARY_SYSTEM asserting the state renders in pCi/L) would lock in the statistics-continuity behavior this PR relies on.

[SUGGESTION] coordinator.py:38-40 — since the library default is already is_metric=True, the argument could be dropped entirely; keeping it explicit with the comment is also defensible given the old code toggled it. Take it or leave it.

[abmantis]

overall LGTM - minor non-blocking suggestions

[SUGGESTION] tests/components/airthings_ble/test_sensor.py — no test asserts the new behavior. A small test verifying the radon sensors report device_class: radon with Bq/m³ native unit (and ideally one with US_CUSTOMARY_SYSTEM asserting the state renders in pCi/L) would lock in the statistics-continuity behavior this PR relies on.

No need, IMO, since we now rely on default behavior (we usually don't add unit conversion tests on integrations).

[SUGGESTION] coordinator.py:38-40 — since the library default is already is_metric=True, the argument could be dropped entirely; keeping it explicit with the comment is also defensible given the old code toggled it. Take it or leave it.

I prefer to keep that explicit.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.