kotlin-specialist

Jeffallan/claude-skillsCoding AgentsReview advisedSnapshot 84ecbf3d8a08

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Summary

Provides idiomatic Kotlin implementation patterns including coroutine concurrency, Flow stream handling, multiplatform architecture, Compose UI construction, Ktor server setup, and type-safe DSL design. Use when building Kotlin applications requiring coroutines, multiplatform development, or Android with Compose. Invoke for Flow API, KMP projects, Ktor servers, DSL design, sealed classes, suspend function, Android Kotlin, Kotlin Multiplatform.

SKILL.md

Kotlin Specialist

Senior Kotlin developer with deep expertise in coroutines, Kotlin Multiplatform (KMP), and modern Kotlin 1.9+ patterns.

Core Workflow

Analyze architecture - Identify platform targets, coroutine patterns, shared code strategy
Design models - Create sealed classes, data classes, type hierarchies
Implement - Write idiomatic Kotlin with coroutines, Flow, extension functions
- Checkpoint: Verify coroutine cancellation is handled (parent scope cancelled on teardown) and null safety is enforced before proceeding
Validate - Run detekt and ktlint; verify coroutine cancellation handling and null safety
- If detekt/ktlint fails: Fix all reported issues and re-run both tools before proceeding to step 5
Optimize - Apply inline classes, sequence operations, compilation strategies
Test - Write multiplatform tests with coroutine test support (runTest, Turbine)

Reference Guide

Load detailed guidance based on context:

Topic	Reference	Load When
Coroutines & Flow	`references/coroutines-flow.md`	Async operations, structured concurrency, Flow API
Multiplatform	`references/multiplatform-kmp.md`	Shared code, expect/actual, platform setup

sealed class UiState<out T> {
    data object Loading : UiState<Nothing>()
    data class Success<T>(val data: T) : UiState<T>()
    data class Error(val message: String, val cause: Throwable? = null) : UiState<Nothing>()
}

// Consume exhaustively — compiler enforces all branches
fun render(state: UiState<User>) = when (state) {
    is UiState.Loading  -> showSpinner()
    is UiState.Success  -> showUser(state.data)
    is UiState.Error    -> showError(state.message)
}

// Use structured concurrency — never GlobalScope
class UserRepository(private val api: UserApi, private val scope: CoroutineScope) {

    fun userUpdates(id: String): Flow<UiState<User>> = flow {
        emit(UiState.Loading)
        try {
            emit(UiState.Success(api.fetchUser(id)))
        } catch (e: IOException) {
            emit(UiState.Error("Network error", e))
        }
    }.flowOn(Dispatchers.IO)

    private val _user = MutableStateFlow<UiState<User>>(UiState.Loading)
    val user: StateFlow<UiState<User>> = _user.asStateFlow()
}

// Anti-pattern — blocks the calling thread; avoid in production
// runBlocking { api.fetchUser(id) }

// Prefer safe calls and elvis operator
val displayName = user?.profile?.name ?: "Anonymous"

// Use let to scope nullable operations
user?.email?.let { email -> sendNotification(email) }

// !! only when the null case is a true contract violation and documented
val config = requireNotNull(System.getenv("APP_CONFIG")) { "APP_CONFIG must be set" }

// apply — configure an object, returns receiver
val request = HttpRequest().apply {
    url = "https://api.example.com/users"
    headers["Authorization"] = "Bearer $token"
}

// let — transform nullable / introduce a local scope
val length = name?.let { it.trim().length } ?: 0

// also — side-effects without changing the chain
val user = createUser(form).also { logger.info("Created user ${it.id}") }

kotlin-specialist

Summary

SKILL.md

Kotlin Specialist

Core Workflow

Reference Guide

Key Patterns

Sealed Classes for State Modeling

Coroutines & Flow

Null Safety

Scope Functions

Constraints

MUST DO

MUST NOT DO

Output Templates

Knowledge Reference

Related skills