swift-concurrency
by JoannisThe swift-concurrency skill helps you review async/await refactors, actor isolation, Sendable issues, task structure, and Swift 6 migration with less guesswork. Use it for practical code editing when compiler warnings, data races, or isolation boundaries matter, and when you need a swift-concurrency guide grounded in repo-backed conventions.
This skill scores 84/100, which means it is a solid listing candidate for Agent Skills Finder. The repository gives directory users a credible install decision: it has a valid frontmatter, a substantial skill body, and detailed Swift Concurrency guidance with explicit trigger conditions and workflow rules. Users should install it if they want a purpose-built skill for async/await, actors, Sendable, task groups, Swift 6 migration, and concurrency diagnostics rather than relying on a generic prompt.
- Strong triggerability: the description names many concrete user intents, including async/await, actors, Swift 6 migration, Sendable, AsyncSequence, and concurrency warnings.
- Operational guidance is real and specific: the skill includes an agent behavior contract with rules about checking language mode, identifying isolation boundaries, avoiding blanket @MainActor fixes, and preferring structured concurrency.
- Good supporting depth: 11 H2 sections, 8 H3 sections, code examples, and 10 references suggest reusable workflow content rather than a thin overview.
- No install command in SKILL.md, so users may need extra manual setup or discovery steps before using it.
- The evidence is strong on guidance but weaker on hands-on execution aids: there are no scripts or resources, so adoption depends on the agent following the written rules correctly.
Overview of swift-concurrency skill
What this skill does
The swift-concurrency skill helps you reason about Swift Concurrency problems with fewer guesses: async/await refactors, actor isolation, Sendable, task structure, strict concurrency warnings, and Swift 6 migration issues. It is a good fit when you need practical review help, not just definitions.
Who it is best for
Use the swift-concurrency skill when you are:
- migrating code to Swift 6 or stricter compiler checks
- fixing data races, actor isolation errors, or
Sendablewarnings - replacing callbacks with
async/await - deciding between
@MainActor, custom actors,nonisolated, or task groups - checking whether code is concurrency-safe before shipping
What makes it different
This swift-concurrency skill is decision-oriented. It emphasizes the isolation boundary, structured concurrency, and the compiler settings that change diagnostics. That matters because the same code can be valid, noisy, or broken depending on language mode and toolchain.
When it is a poor fit
If you only need a quick syntax refresher, a generic prompt may be enough. The swift-concurrency skill is more useful when the answer depends on project context, compiler behavior, or a real migration path.
How to Use swift-concurrency skill
Install it in the right repo context
Use the swift-concurrency install flow for your skills setup, then apply it where you are editing Swift code. A typical install command is:
npx skills add Joannis/claude-skills --skill swift-concurrency
If your environment uses a different skills manager, keep the same skill slug and point it at the Joannis/claude-skills repository.
Give it the right input shape
Strong swift-concurrency usage starts with a concrete code goal, not a vague topic. Include:
- the file or type you want changed
- the compiler error or warning text
- whether the target is Swift 5.x or Swift 6
- the relevant isolation boundary, if known
- whether UI code, server code, or shared model code is involved
Good prompt:
Refactor this callback-based networking code to
async/await, but keep UI updates on@MainActoronly where needed. We are on Swift 6 and the compiler warns aboutSendablecaptures.
Weak prompt:
Help with Swift concurrency.
Read the right files first
For faster and safer results, inspect SKILL.md first, then the most relevant references:
references/glossary.mdfor terminologyreferences/async-await-basics.mdfor conversion patternsreferences/actors.mdfor isolation and actor accessreferences/sendable.mdfor capture and transfer issuesreferences/performance.mdfor parallelism and contention
If you are working on production architecture or tests, also check references/production-patterns.md and references/testing.md.
Workflow that usually works
- Identify the exact warning, error, or refactor target.
- Determine the isolation domain: main actor, custom actor, or nonisolated.
- Decide whether the change is structural concurrency, not just syntax cleanup.
- Ask for the smallest safe fix first.
- Then request a follow-up pass for performance, testability, or Swift 6 cleanup.
swift-concurrency skill FAQ
Is this just a better prompt for Swift Concurrency?
No. The swift-concurrency skill is a reusable guide with repo-backed conventions for handling isolation, Sendable, and migration choices. It is better than a generic prompt when the answer depends on compiler mode or on how tasks and actors are structured.
Do I need to know async/await already?
No. The skill still helps beginners, but it is most useful if you can share the code and the error. If you only know the desired behavior, provide a minimal example and let the skill shape the concurrency model.
Does it work for server-side Swift and app code?
Yes. It fits both, but the advice should differ. UI code often needs @MainActor; server or library code usually needs narrower isolation and more care with Sendable and task structure.
When should I not use it?
Do not use swift-concurrency for unrelated async APIs in other languages, or when the problem is purely business logic with no actor, task, or compiler-concurrency angle. It is also a poor fit if you cannot share enough context to identify the isolation boundary.
How to Improve swift-concurrency skill
Provide the compiler facts up front
The biggest quality boost comes from telling the skill which language mode and toolchain you are using. Swift 5.10, Swift 6, and strict concurrency settings can lead to different answers. Include the exact warning text when possible.
Show the boundary, not just the symptom
The skill performs better when you say where state lives and who touches it. For example:
- “This cache is shared across request tasks”
- “This view model updates UIKit state”
- “This parser should stay off the main actor”
That helps the swift-concurrency skill choose between actor isolation, nonisolated, @MainActor, or task grouping.
Ask for the smallest safe change first
A good swift-concurrency guide request asks for the least invasive fix that compiles cleanly. If you need deeper help later, ask for a second pass on performance, cancellation, or architecture. This avoids overcorrecting with blanket @MainActor or unnecessary Task.detached.
Iterate with the next warning, not a rewrite
After the first answer, feed back the next compiler diagnostic or runtime concern. The best swift-concurrency for Code Editing workflows are incremental: fix one isolation issue, recompile, then refine Sendable, cancellation, or task structure based on the new output.