RPC Server Service loses transport coroutine context

[yakivy]

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Describe the bug I have CallID Ktor plugin installed, it sets correct MDC for SLF4J, but it is lost during actual service logic (that probably means that it is called in different than transport coroutine context)

To Reproduce Kotlin version - 2.0.10 Gradle version - 8.8 OS (Or at least KMP platform) - mac os sonoma Kotlin RPC version - 0.2.4 Steps to reproduce the behavior:

• create a simple ktor server
• install CallID plugins:

    install(CallId) {
        generate { call -> "test" }
        verify { it.isNotBlank() }
    }
    install(CallLogging) {
        callIdMdc()
    }

• register simple RPC service:

interface FileParsingService : RPC {
  suspend fun parse(): Unit
}

class FileParsingInternalService(
  override val coroutineContext: CoroutineContext,
): FileParsingService {
  override suspend fun parse(): Unit = println("MDC: " + MDC.getCopyOfContextMap())
}

registerService<FileParsingService> { FileParsingInternalService(it) }

• call our RPC server

Actual behavior You see MDC: null in console

Expected behavior You see MDC: {callId=test} in console

Additional context Link to a small slack discussion: https://kotlinlang.slack.com/archives/C072YJ3Q91V/p1730721325535899

Probably the main cause of the problem is here: https://github.com/Kotlin/kotlinx-rpc/blob/main/krpc/krpc-server/src/jvmMain/kotlin/kotlinx/rpc/krpc/server/internal/RPCServerService.kt#L175 Actual RPC service logic is called in the RPC service coroutine context (Child Supervisor Job) instead of transport coroutine context (that has MDCContext). My naive approach would be to make the method suspended and launch service call on kotlin.coroutines.coroutineContext, but probably it will break control flow.