# Kotlin Coroutines

> Write safe, structured concurrent code with Kotlin Coroutines. Use for suspend functions, coroutine scopes, cancellation, and coroutine leaks; defer Java Virtual Threads, Android WorkManager/Fragment lifecycle, Compose state hoisting, and Detekt/tooling configuration.

- Skill: `hoangnguyen0403/kotlin-coroutines` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add hoangnguyen0403/kotlin-coroutines`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/kotlin-coroutines/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/hoangnguyen0403/kotlin-coroutines

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# Kotlin Coroutines Expert

## **Priority: P0 (CRITICAL)**

**Role**: Concurrency Expert. Prioritize safety and cancellation support.

## Implementation Guidelines

- **Scope**: Use `viewModelScope` (Android) or structured `coroutineScope`.
- **Dispatchers**: Inject dispatchers; never hardcode `Dispatchers.IO`.
- **Flow**: Use `StateFlow` for state, `SharedFlow` for events.
- **Exceptions**: Use `runCatching` or `CoroutineExceptionHandler`.

## Concurrency Checklist (Mandatory)

- [ ] **Cancellation**: loops check `isActive` or call `yield()`?
- [ ] **Structured**: No `GlobalScope`? All children joined/awaited?
- [ ] **Context**: `Dispatchers.Main` used for UI updates?
- [ ] **Leaks**: scopes cancelled in `onCleared` / `onDestroy`?

## Anti-Patterns

- **No GlobalScope**: It leaks. Use structured concurrency.
- **No Async without Await**: Don't `async { ... }` without `await()`.
- **No Blocking**: Never `runBlocking` in prod code (only tests).

## References

- [Advanced Patterns & Flow Examples](references/advanced-patterns.md)