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guide-swift-concurrency

Swift concurrency patterns — actors, structured concurrency, cancellation, async streams, GCD migration, strict-concurrency diagnostics, common bug patterns. Use when writing, reviewing, or debugging concurrent Swift code.

skills/guide-swift-concurrency/SKILL.md

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SKILL.mdcore · 3,531 bytes
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references/async-streams.mddoc · 2,107 bytes
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references/bug-patterns.mddoc · 4,182 bytes
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> **Guide Skill** — This is an expert workflow/pattern guide, not API reference documentation.
> Originally from [twostraws/Swift-Concurrency-Agent-Skill](https://github.com/twostraws/Swift-Concurrency-Agent-Skill) by Paul Hudson. MIT License.

# Swift Concurrency Patterns

Review and write Swift concurrency code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems — do not nitpick or invent issues.

## Core Instructions

- Target Swift 6.2 or later with strict concurrency checking.
- Prefer structured concurrency (task groups) over unstructured (`Task {}`).
- Prefer Swift concurrency over GCD for new code. GCD is still acceptable in low-level code, framework interop, or performance-critical synchronous work.
- Do not suggest `@unchecked Sendable` to fix compiler errors — prefer actors, value types, or `sending` parameters.