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Observability Reference

API reference for logging, metrics, and explainability: registry hooks, evaluation results, and deterministic bucketing.

RegistryHooks​

Dependency-free hooks for logging and metrics adapters.

data class RegistryHooks(
    val logger: KonditionalLogger = KonditionalLogger.NoOp,
    val metrics: MetricsCollector = MetricsCollector.NoOp,
)

Attach hooks to a namespace via setHooks(...):

AppFeatures.setHooks(
    RegistryHooks.of(
        logger = myLogger,
        metrics = myMetrics,
    )
)

KonditionalLogger​

Minimal logging interface used by the runtime.

interface KonditionalLogger {
    fun debug(message: () -> String) {}
    fun info(message: () -> String) {}
    fun warn(message: () -> String, throwable: Throwable? = null) {}
    fun error(message: () -> String, throwable: Throwable? = null) {}
}

MetricsCollector​

Minimal metrics interface used by the runtime.

interface MetricsCollector {
    fun recordEvaluation(event: Metrics.Evaluation) {}
    fun recordConfigLoad(event: Metrics.ConfigLoadMetric) {}
    fun recordConfigRollback(event: Metrics.ConfigRollbackMetric) {}
}
Advanced Options

EvaluationResult<T>​

Returned by Feature.explain(...).

data class EvaluationResult<T : Any>(
    val namespaceId: String,
    val featureKey: String,
    val configVersion: String?,
    val mode: Metrics.Evaluation.EvaluationMode,
    val durationNanos: Long,
    val value: T,
    val decision: Decision,
)

BucketInfo and RampUpBucketing​

Deterministic ramp-up bucketing utilities (guaranteed to match runtime evaluation behavior).

object RampUpBucketing {
    fun bucket(stableId: StableId, featureKey: String, salt: String): Int
    fun explain(stableId: StableId, featureKey: String, salt: String, rampUp: RampUp): BucketInfo
}

ShadowMismatch<T>​

Result type passed to shadow mismatch callbacks.

data class ShadowMismatch<T : Any>(
    val featureKey: String,
    val baseline: EvaluationResult<T>,
    val candidate: EvaluationResult<T>,
    val kinds: Set<Kind>,
)

Next steps​