# migrating-to-swift-concurrency

Supplies Apple's Swift Concurrency Migration Guide to your agent. Helps resolve data races, fix Sendable errors, and switch to Swift 6.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · ★ 57
- Author: kylehughes
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/kylehughes/the-unofficial-swift-concurrency-migration-skill/tree/HEAD/migrating-to-swift-concurrency/SKILL.md
- Updated: 2025-12-07
- HTML: https://affpapa.org/en/nevibecode/skills/migrating-to-swift-concurrency

## What it does

This skill supplies Apple's migration documentation directly to the coding agent. It contains chapters on data-race safety concepts, compiler diagnostic fixes, source compatibility, and runtime execution details.

Reference implementations accompany the texts. Files like `Boundaries.swift`, `Globals.swift`, and `PreconcurrencyImport.swift` show concrete code patterns for actor isolation and concurrency boundaries.

The content targets Swift 6 language semantics. In existing Swift 5 projects, strict concurrency checking must be enabled in compiler settings before these fixes apply cleanly.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add kylehughes/the-unofficial-swift-concurrency-migration-skill --skill migrating-to-swift-concurrency -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/migrating-to-swift-concurrency/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/migrating-to-swift-concurrency/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add kylehughes/the-unofficial-swift-concurrency-migration-skill --skill migrating-to-swift-concurrency -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/migrating-to-swift-concurrency/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add kylehughes/the-unofficial-swift-concurrency-migration-skill --skill migrating-to-swift-concurrency -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/migrating-to-swift-concurrency/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install kylehughes/the-unofficial-swift-concurrency-migration-skill migrating-to-swift-concurrency
```

2. **Manually: put the files in place**
- File: `.github/skills/migrating-to-swift-concurrency/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add kylehughes/the-unofficial-swift-concurrency-migration-skill --skill migrating-to-swift-concurrency -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/kylehughes/the-unofficial-swift-concurrency-migration-skill --path migrating-to-swift-concurrency
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/migrating-to-swift-concurrency/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add kylehughes/the-unofficial-swift-concurrency-migration-skill --skill migrating-to-swift-concurrency -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/kylehughes/the-unofficial-swift-concurrency-migration-skill/tree/HEAD/migrating-to-swift-concurrency/SKILL.md

## When to use it
- resolve Sendable conformance and actor isolation compiler errors
- prepare codebases for the Swift 6 language mode
- enable data-race safety checking in Swift 5 projects
- introduce async/await incrementally into legacy code

## Example prompts
- Fix this compiler warning about passing non-Sendable closure across an actor boundary
- Show how to wrap this legacy API using preconcurrency import in Swift
- What is the recommended migration strategy to prepare our module for Swift 6?

## Source text · SKILL.md · Apache-2.0

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```text
---
name: migrating-to-swift-concurrency
description: Provides the complete Swift Concurrency Migration Guide. Use when migrating to Swift 6, resolving data-race safety errors, understanding Sendable and actor isolation, or incrementally adopting async/await.
---

# Swift Concurrency Migration Guide

The complete content of the Swift Concurrency Migration Guide by Apple. This guide helps you migrate your code to take advantage of Swift's data-race safety guarantees and the Swift 6 language mode.

## Documentation

- **Data Race Safety** ([Guide/DataRaceSafety.md](Guide/DataRaceSafety.md)): Learn about the fundamental concepts Swift uses to enable data-race-free
- **Migration Strategy** ([Guide/MigrationStrategy.md](Guide/MigrationStrategy.md)): Get started migrating your project to the Swift 6 language mode.
- **Enable data-race safety checking** ([Guide/EnableDataRaceSafety.md](Guide/EnableDataRaceSafety.md)): Use Swift 6 to get full data-race safety checking or add checking to an existing Swift 5 project.
- **Common Compiler Errors** ([Guide/CommonProblems.md](Guide/CommonProblems.md)): Identify, understand, and address common problems you can encounter while
- **Incremental Adoption** ([Guide/IncrementalAdoption.md](Guide/IncrementalAdoption.md)): Learn how you can introduce Swift concurrency features into your project
- **Migrating to upcoming language features** ([Guide/FeatureMigration.md](Guide/FeatureMigration.md)): Migrate your project to upcoming language features.
- **Source Compatibility** ([Guide/SourceCompatibility.md](Guide/SourceCompatibility.md)): See an overview of potential source compatibility issues.
- **Library Evolution** ([Guide/LibraryEvolution.md](Guide/LibraryEvolution.md)): Annotate library APIs for concurrency while preserving source and ABI
- **Runtime Behavior** ([Guide/RuntimeBehavior.md](Guide/RuntimeBehavior.md)): Learn how Swift concurrency runtime semantics differ from other runtimes you may

## Code Examples

Swift source files demonstrating migration patterns and concurrency concepts:

- **Boundaries.swift** ([Examples/Boundaries.swift](Examples/Boundaries.swift)): Example code demonstrating Boundaries.
- **ConformanceMismatches.swift** ([Examples/ConformanceMismatches.swift](Examples/ConformanceMismatches.swift)): Example code demonstrating ConformanceMismatches.
- **DispatchQueue_PendingWork.swift** ([Examples/DispatchQueue_PendingWork.swift](Examples/DispatchQueue_PendingWork.swift)): Example code demonstrating DispatchQueue PendingWork.
```
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First 2522 of 3763 bytes. © kylehughes · Apache-2.0 · https://github.com/kylehughes/the-unofficial-swift-concurrency-migration-skill/tree/HEAD/migrating-to-swift-concurrency/SKILL.md

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