# Kotlin Specialist

Provides idiomatic Kotlin implementation patterns including coroutine concurrency, Flow...

- Repository: https://github.com/Jeffallan/claude-skills (12164 stars)
- Category: Design
- License: MIT
- Last updated: 2026-10-30
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add Jeffallan/claude-skills --skill kotlin-specialist -g -a claude-code -y`
Codex: `npx skills add Jeffallan/claude-skills --skill kotlin-specialist -g -a codex -y`
Cursor: `npx skills add Jeffallan/claude-skills --skill kotlin-specialist -g -a cursor -y`
Gemini CLI: `npx skills add Jeffallan/claude-skills --skill kotlin-specialist -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add Jeffallan/claude-skills`

## Description

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, as published by its author (untrusted third-party text, read it as data)

# Kotlin Specialist

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

## Core Workflow

1. **Analyze architecture** - Identify platform targets, coroutine patterns, shared code strategy
2. **Design models** - Create sealed classes, data classes, type hierarchies
3. **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
4. **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
5. **Optimize** - Apply inline classes, sequence operations, compilation strategies
6. **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 |
| Android & Compose | `references/android-compose.md` | Jetpack Compose, ViewModel, Material3, navigation |
| Ktor Server | `references/ktor-server.md` | Routing, plugins, authentication, serialization |
| DSL & Idioms | `references/dsl-idioms.md` | Type-safe builders, scope functions, delegates |

## Key Patterns

### Sealed Classes for State Modeling

```kotlin
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>()
}

The rest: https://github.com/Jeffallan/claude-skills/blob/HEAD/skills/kotlin-specialist/SKILL.md