KMP Support

Kotlin Multiplatform Support

The Rebound runtime is a Kotlin Multiplatform (KMP) library. The compiler plugin instruments composable functions regardless of target platform.

Supported Targets

Target	Status	Notes
Android	Full support	Socket transport, state tracking, logcat output
JVM (Desktop)	Core metrics	Rate tracking, violation detection. No socket transport.
iOS arm64	Core metrics	Rate tracking, violation detection
iOS x64	Core metrics	Rate tracking, violation detection
iOS Simulator arm64	Core metrics	Rate tracking, violation detection
Wasm (JS)	Core metrics	Rate tracking, violation detection

What Works Everywhere

The following features are implemented in commonMain and work on all targets:

• Budget class assignment — composables are classified at compile time, which is platform-independent
• Recomposition rate tracking — the sliding window rate calculation uses kotlinx.datetime or platform time APIs
• Violation detection — budget comparison logic is pure Kotlin
• Skip rate tracking — onEnter/onComposition counting is platform-independent
• $changed bitmask decoding — pure bit manipulation, no platform dependencies
• Baseline snapshot comparison — JSON export and diff logic

Android-Specific Features

The following features are available only on Android:

• Socket transport (ReboundServer) — uses android.net.LocalServerSocket for Unix domain socket communication
• State invalidation tracking (StateTracker) — uses androidx.compose.runtime.Snapshot.registerApplyObserver
• Logcat output — uses android.util.Log for violation warnings
• IDE plugin connectivity — the IDE plugin connects via ADB forward, which requires an Android device

Platform Considerations

Desktop (JVM)

On Desktop Compose, Rebound tracks metrics but has no built-in transport to export them. You can access metrics programmatically:

// Access metrics directly in your Desktop app
val snapshot = ReboundTracker.exportSnapshot()
println(snapshot.toJson())

Future work may add a local TCP server for Desktop targets.

iOS

On iOS, the compiler plugin instruments composables in Compose Multiplatform shared code. Metrics are tracked at runtime. Export requires programmatic access via ReboundTracker.exportSnapshot().

Wasm

The Wasm target supports core metrics. Browser-based transport (e.g., WebSocket) is not yet implemented.

Gradle Configuration for KMP

The Rebound Gradle plugin works with KMP projects. Apply it to the module that contains your composable code:

shared/build.gradle.kts

plugins {
    id("org.jetbrains.kotlin.multiplatform")
    id("org.jetbrains.compose")
    id("org.jetbrains.kotlin.plugin.compose")
    id("io.github.aldefy.rebound") version "0.1.0"
}

The plugin adds the compiler artifact to all Kotlin compilation tasks and the runtime to the appropriate source sets.