Context

We conducted a cross-SDK comparison of all MultiProvider implementations using the js-sdk as the reference. The Kotlin MultiProvider is functional for basic use cases, but we identified several gaps relative to the reference implementation. Hook support is already tracked in #171.

Gaps

1. Tracking event forwarding (High)

The MultiProvider inherits the default no-op track() from FeatureProvider. Tracking events are not forwarded to child providers.

Expected behavior:

• Iterate over child providers and forward track() calls
• Skip providers that are not in a ready/active state
• Errors from individual track() calls should be caught and logged, not propagated

Reference: js-sdk multi-provider.ts track(), dotnet-sdk MultiProvider.cs Track()

2. Strategy should be able to skip NOT_READY/FATAL providers (Medium)

The Strategy.evaluate() method receives a List<FeatureProvider> with no status information. Strategies cannot preemptively skip providers that are NOT_READY or FATAL -- they must attempt evaluation and handle the resulting error reactively. The childProviderStatuses map is private to MultiProvider and not exposed.

Expected behavior:

• The strategy should receive per-provider status alongside each provider (e.g. via a wrapper type or extended context)
• The default behavior should skip providers in NOT_READY or FATAL status before attempting evaluation
• This avoids unnecessary evaluation attempts and cleaner error handling

Reference: js-sdk BaseEvaluationStrategy.shouldEvaluateThisProvider(), dotnet-sdk BaseEvaluationStrategy.ShouldEvaluateThisProvider()

3. ComparisonStrategy (Medium)

Only FirstMatchStrategy and FirstSuccessfulStrategy exist. There is no ComparisonStrategy for evaluating all providers and comparing results (useful for migration validation and consistency checks).

Expected behavior:

• Evaluate all providers (ideally in parallel)
• If all providers agree on the value, return it
• If providers disagree, call an optional onMismatch callback and return the designated fallback provider's result
• If any provider errors, collect and report all errors
• Constructor accepts a fallbackProvider and optional onMismatch callback

Reference: js-sdk comparison-strategy.ts, go-sdk comparison_strategy.go, dotnet-sdk ComparisonStrategy.cs

Related Issues

• Support hooks in MultiProvider #171 — Hook support in MultiProvider

Spec Reference

https://openfeature.dev/specification/appendix-a/#multi-provider