# Kotlin Concurrency Expert

Kotlin Coroutines review and remediation for Android.

- Repository: https://github.com/new-silvermoon/awesome-android-agent-skills (998 stars)
- Category: Mobile
- License: Apache-2.0
- Last updated: 2026-07-27
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add new-silvermoon/awesome-android-agent-skills --skill kotlin-concurrency-expert -g -a claude-code -y`
Codex: `npx skills add new-silvermoon/awesome-android-agent-skills --skill kotlin-concurrency-expert -g -a codex -y`
Cursor: `npx skills add new-silvermoon/awesome-android-agent-skills --skill kotlin-concurrency-expert -g -a cursor -y`
Gemini CLI: `npx skills add new-silvermoon/awesome-android-agent-skills --skill kotlin-concurrency-expert -g -a gemini-cli -y`

## Description

Kotlin Coroutines review and remediation for Android. Use when asked to review concurrency usage, fix coroutine-related bugs, improve thread safety, or resolve lifecycle issues in Kotlin/Android code.

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

# Kotlin Concurrency Expert

## Overview

Review and fix Kotlin Coroutines issues in Android codebases by applying structured concurrency, lifecycle safety, proper scoping, and modern best practices with minimal behavior changes.

## Workflow

### 1. Triage the Issue

- Capture the exact error, crash, or symptom (ANR, memory leak, race condition, incorrect state).
- Check project coroutines setup: `kotlinx-coroutines-android` version, `lifecycle-runtime-ktx` version.
- Identify the current scope context (`viewModelScope`, `lifecycleScope`, custom scope, or none).
- Confirm whether the code is UI-bound (`Dispatchers.Main`) or intended to run off the main thread (`Dispatchers.IO`, `Dispatchers.Default`).
- Verify Dispatcher injection patterns for testability.

### 2. Apply the Smallest Safe Fix

Prefer edits that preserve existing behavior while satisfying structured concurrency and lifecycle safety.

Common fixes:

- **ANR / Main thread blocking**: Move heavy work to `withContext(Dispatchers.IO)` or `Dispatchers.Default`; ensure suspend functions are main-safe.
- **Memory leaks / zombie coroutines**: Replace `GlobalScope` with a lifecycle-bound scope (`viewModelScope`, `lifecycleScope`, or injected `applicationScope`).
- **Lifecycle collection issues**: Replace deprecated `launchWhenStarted` with `repeatOnLifecycle(Lifecycle.State.STARTED)`.
- **State exposure**: Encapsulate `MutableStateFlow` / `MutableSharedFlow`; expose read-only `StateFlow` or `Flow`.
- **CancellationException swallowing**: Ensure generic `catch (e: Exception)` blocks rethrow `CancellationException`.
- **Non-cooperative cancellation**: Add `ensureActive()` or `yield()` in tight loops for cooperative cancellation.
- **Callback APIs**: Convert listeners to `callbackFlow` with proper `awaitClose` cleanup.
- **Hardcoded Dispatchers**: Inject `CoroutineDispatcher` via constructor for testability.

## Critical Rules

### Dispatcher Injection (Testability)

The rest: https://github.com/new-silvermoon/awesome-android-agent-skills/blob/HEAD/.github/skills/concurrency_and_networking/kotlin-concurrency-expert/SKILL.md