device health lab

The type is the policy

Data honesty is usually a convention, which means it survives exactly as long as the developer remembers it. Here it is a type. Nothing reaches the UI as a bare number — it arrives as a MetricValue, and rendering one means handling the case where the platform would not answer.

sealed interface MetricValue {
    data class Real(val value: Double, val unit: String) : MetricValue
    data class Estimated(val value: Double, val basis: String) : MetricValue
    data class RootSourced(val value: Double, val path: String) : MetricValue
    data object Unavailable : MetricValue
}

An estimate carries the basis it was derived from. A root-sourced reading carries the sysfs path it came from. Unavailable is a first-class outcome rather than a zero, so an unanswerable question never renders as a confident 0.

Coverage

• Battery health, charge cycles and discharge behaviour over time.
• Thermal zones and throttling events.
• Device and system-performance health sampled on a WorkManager schedule.
• History persisted in Room; preferences in DataStore.