Kotlin Rules

Version: Kotlin 2.0+

Tooling

• Build: Gradle with Kotlin DSL
• Testing: Kotest or JUnit 5
• Linting: ktlint, detekt

Best Practices (2026)

• Use structured concurrency - child tasks auto-cancel with parent
• Never hardcode Dispatchers - inject them for testability
• Never use GlobalScope - makes testing difficult
• Trigger coroutines from ViewModel, not Views
• Use data classes for DTOs, sealed classes for state

Ktor 3.4.0 Features

• Structured concurrency: client disconnect cancels request handling
• Zstd compression support
• OpenAPI generation
• Duplex streaming for OkHttp

Coroutine Patterns

// Inject dispatchers
class UserRepository(
    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
) {
    suspend fun fetchUser(id: String) = withContext(ioDispatcher) {
        api.getUser(id)
    }
}

// Concurrent requests with Ktor client
val responses = coroutineScope {
    urls.map { url ->
        async { client.get(url) }
    }.awaitAll()
}

Android Patterns

• Use Jetpack Compose for UI
• Use Hilt for dependency injection
• Use Flow for reactive streams

MoAI Integration

• Use Skill("moai-lang-kotlin") for detailed patterns
• Follow TRUST 5 quality gates