New: 98,000+ skills indexed from GitHub repos with 100+ stars · every skill safety-checkedBrowse top skillsTop skills
Esc to closeBrowse all skills
Submit a skillBrowse skills
Submit a skillBrowse skills

Agent skill

Swift Concurrency

by AFK-surf in AFK-surf/OpenBridge

Expert guidance on Swift Concurrency best practices, patterns, and implementation.

MITAuto-check passedDevelopment

Install Swift Concurrency

skills CLI
$ npx skills add AFK-surf/OpenBridge --skill swift-concurrency -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install AFK-surf/OpenBridge swift-concurrency --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/AFK-surf/OpenBridge.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/swift-concurrency .claude/skills/swift-concurrency && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
swift-concurrency
GitHub stars
430
Token cost
~2.8k tokens
SKILL.md length
986 words
Files
16 (incl. references)
Skills in repo
14
Repo updated
First seen
Licence
MIT

At a glance

Expert guidance on Swift Concurrency best practices, patterns, and implementation.

  • Works in 7 steps: Analyze the project/package file to find… → Before proposing fixes, identify the… → Do not recommend @MainActor as a blanket… → …
  • Developers mention:
  • SKILL.md covers Overview, Agent Behavior Contract…, Recommended Tools for Analysis and Project Settings Intake…, plus 8 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Swift Concurrency is an agent skill from AFK-surf/OpenBridge. Expert guidance on Swift Concurrency best practices, patterns, and implementation. Use when developers mention: (1) Swift Concurrency, async/await, actors, or tasks, (2) "use Swift Concurrency" or "modern concurrency patterns", (3) migrating to Swift 6, (4) data races or thread safety issues, (5) refactoring closures to async/await, (6) @MainActor, Sendable, or actor isolation, (7) concurrent code architecture or performance optimization, (8) concurrency-related linter warnings (SwiftLint or similar; e.g…

Its SKILL.md is about 2.8k tokens, which your agent loads only when the skill is triggered. The skill folder holds 16 other files, including reference files (for example `references/_index.md`, `references/actors.md` and `references/async-algorithms.md`).

It sits in Development, covering Async programming, Linting and formatting and Performance optimization. It works with Swift. The repository describes itself as: A free, safe and open agent for everything. Alternative to Claude Cowork & Codex. Open Bridge, the AI bridge between your intention and get the job done. The licence is MIT.

When your agent uses it

  • Developers mention:
  • Swift Concurrency
  • Use Swift Concurrency
  • Modern concurrency patterns

Example prompts

  • “use Swift Concurrency”
  • “modern concurrency patterns”
  • “/swift-concurrency”

Workflow steps

7 steps, taken from the first numbered list in SKILL.md.

  1. Analyze the project/package file to find out which Swift language mode (Swift 5.x vs Swift 6) and which Xcode/Swift toolchain is used when…
  2. Before proposing fixes, identify the isolation boundary: @MainActor, custom actor, actor instance isolation, or nonisolated.
  3. Do not recommend @MainActor as a blanket fix. Justify why main-actor isolation is correct for the code.
  4. Prefer structured concurrency (child tasks, task groups) over unstructured tasks. Use Task.detached only with a clear reason.
  5. If recommending @preconcurrency, @unchecked Sendable, or nonisolated(unsafe), require
  6. For migration work, optimize for minimal blast radius (small, reviewable changes) and add verification steps.
  7. Course references are for deeper learning only. Use them sparingly and only when they clearly help answer the developer's question.

What it can do on your machine

Read from SKILL.md and the folder at commit a9ca905. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are swift).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • swiftconcurrencycourse.com

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Swift Concurrency loads about 2.8k tokens when it runs, and up to ~51k if it reads all its reference files. Until then it costs about 148 tokens; SKILL.md has 986 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~148
When it runs · the whole SKILL.md, loaded when a task matches
~2.8k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~51k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from AFK-surf/OpenBridge at commit a9ca905, republished under its MIT licence (© AFK-surf). 986 words, ~2,817 tokens.

Download SKILL.mdSave it as .claude/skills/swift-concurrency/SKILL.md (or your agent's skills folder). This skill also uses 15 other files; get the full folder from GitHub.
name
swift-concurrency
description
Expert guidance on Swift Concurrency best practices, patterns, and implementation. Use when developers mention: (1) Swift Concurrency, async/await, actors, or tasks, (2) "use Swift Concurrency" or "modern concurrency patterns", (3) migrating to Swift 6, (4) data races or thread safety issues, (5) refactoring closures to async/await, (6) @MainActor, Sendable, or actor isolation, (7) concurrent code architecture or performance optimization, (8) concurrency-related linter warnings (SwiftLint or similar; e.g. async_without_await, Sendable/actor isolation/MainActor lint).

Swift Concurrency

Overview

This skill provides expert guidance on Swift Concurrency, covering modern async/await patterns, actors, tasks, Sendable conformance, and migration to Swift 6. Use this skill to help developers write safe, performant concurrent code and navigate the complexities of Swift's structured concurrency model.

Agent Behavior Contract (Follow These Rules)

  1. Analyze the project/package file to find out which Swift language mode (Swift 5.x vs Swift 6) and which Xcode/Swift toolchain is used when advice depends on it.
  2. Before proposing fixes, identify the isolation boundary: @MainActor, custom actor, actor instance isolation, or nonisolated.
  3. Do not recommend @MainActor as a blanket fix. Justify why main-actor isolation is correct for the code.
  4. Prefer structured concurrency (child tasks, task groups) over unstructured tasks. Use Task.detached only with a clear reason.
  5. If recommending @preconcurrency, @unchecked Sendable, or nonisolated(unsafe), require:
    • a documented safety invariant
    • a follow-up ticket to remove or migrate it
  6. For migration work, optimize for minimal blast radius (small, reviewable changes) and add verification steps.
  7. Course references are for deeper learning only. Use them sparingly and only when they clearly help answer the developer's question.

When analyzing Swift projects for concurrency issues:

  1. Project Settings Discovery
    • Use Read on Package.swift for SwiftPM settings (tools version, strict concurrency flags, upcoming features)
    • Use Grep for SWIFT_STRICT_CONCURRENCY or SWIFT_DEFAULT_ACTOR_ISOLATION in .pbxproj files
    • Use Grep for SWIFT_UPCOMING_FEATURE_ to find enabled upcoming features

Project Settings Intake (Evaluate Before Advising)

Concurrency behavior depends on build settings. Always try to determine:

  • Default actor isolation (is the module default @MainActor or nonisolated?)
  • Strict concurrency checking level (minimal/targeted/complete)
  • Whether upcoming features are enabled (especially NonisolatedNonsendingByDefault)
  • Swift language mode (Swift 5.x vs Swift 6) and SwiftPM tools version
Manual checks (no scripts)
  • SwiftPM:
    • Check Package.swift for .defaultIsolation(MainActor.self).
    • Check Package.swift for .enableUpcomingFeature("NonisolatedNonsendingByDefault").
    • Check for strict concurrency flags: .enableExperimentalFeature("StrictConcurrency=targeted") (or similar).
    • Check tools version at the top: // swift-tools-version: ...
  • Xcode projects:
    • Search project.pbxproj for:
      • SWIFT_DEFAULT_ACTOR_ISOLATION
      • SWIFT_STRICT_CONCURRENCY
      • SWIFT_UPCOMING_FEATURE_ (and/or SWIFT_ENABLE_EXPERIMENTAL_FEATURES)

If any of these are unknown, ask the developer to confirm them before giving migration-sensitive guidance.

Quick Decision Tree

When a developer needs concurrency guidance, follow this decision tree:

  1. Starting fresh with async code?

    • Read references/async-await-basics.md for foundational patterns
    • For parallel operations → references/tasks.md (async let, task groups)

  2. Protecting shared mutable state?

    • Need to protect class-based state → references/actors.md (actors, @MainActor)
    • Need thread-safe value passing → references/sendable.md (Sendable conformance)

  3. Managing async operations?

    • Structured async work → references/tasks.md (Task, child tasks, cancellation)
    • Streaming data → references/async-sequences.md (AsyncSequence, AsyncStream)

  4. Working with legacy frameworks?

    • Core Data integration → references/core-data.md
    • General migration → references/migration.md

  5. Performance or debugging issues?

    • Slow async code → references/performance.md (profiling, suspension points)
    • Testing concerns → references/testing.md (XCTest, Swift Testing)

  6. Understanding threading behavior?

    • Read references/threading.md for thread/task relationship and isolation

  7. Memory issues with tasks?

    • Read references/memory-management.md for retain cycle prevention

Triage-First Playbook (Common Errors -> Next Best Move)

  • SwiftLint concurrency-related warnings
    • Use references/linting.md for rule intent and preferred fixes; avoid dummy awaits as “fixes”.
  • SwiftLint async_without_await warning
    • Remove async if not required; if required by protocol/override/@concurrent, prefer narrow suppression over adding fake awaits. See references/linting.md.
  • "Sending value of non-Sendable type ... risks causing data races"
    • First: identify where the value crosses an isolation boundary
    • Then: use references/sendable.md and references/threading.md (especially Swift 6.2 behavior changes)
  • "Main actor-isolated ... cannot be used from a nonisolated context"
    • First: decide if it truly belongs on @MainActor
    • Then: use references/actors.md (global actors, nonisolated, isolated parameters) and references/threading.md (default isolation)
  • "Class property 'current' is unavailable from asynchronous contexts" (Thread APIs)
    • Use references/threading.md to avoid thread-centric debugging and rely on isolation + Instruments
  • XCTest async errors like "wait(...) is unavailable from asynchronous contexts"
    • Use references/testing.md (await fulfillment(of:) and Swift Testing patterns)
  • Core Data concurrency warnings/errors
    • Use references/core-data.md (DAO/NSManagedObjectID, default isolation conflicts)
Show full SKILL.md (376 more words)Show less

Core Patterns Reference

When to Use Each Concurrency Tool

async/await - Making existing synchronous code asynchronous

swift
// Use for: Single asynchronous operations
func fetchUser() async throws -> User {
    try await networkClient.get("/user")
}

async let - Running multiple independent async operations in parallel

swift
// Use for: Fixed number of parallel operations known at compile time
async let user = fetchUser()
async let posts = fetchPosts()
let profile = try await (user, posts)

Task - Starting unstructured asynchronous work

swift
// Use for: Fire-and-forget operations, bridging sync to async contexts
Task {
    await updateUI()
}

Task Group - Dynamic parallel operations with structured concurrency

swift
// Use for: Unknown number of parallel operations at compile time
await withTaskGroup(of: Result.self) { group in
    for item in items {
        group.addTask { await process(item) }
    }
}

Actor - Protecting mutable state from data races

swift
// Use for: Shared mutable state accessed from multiple contexts
actor DataCache {
    private var cache: [String: Data] = [:]
    func get(_ key: String) -> Data? { cache[key] }
}

@MainActor - Ensuring UI updates on main thread

swift
// Use for: View models, UI-related classes
@MainActor
class ViewModel: ObservableObject {
    @Published var data: String = ""
}
Common Scenarios

Scenario: Network request with UI update

swift
Task { @concurrent in
    let data = try await fetchData() // Background
    await MainActor.run {
        self.updateUI(with: data) // Main thread
    }
}

Scenario: Multiple parallel network requests

swift
async let users = fetchUsers()
async let posts = fetchPosts()
async let comments = fetchComments()
let (u, p, c) = try await (users, posts, comments)

Scenario: Processing array items in parallel

swift
await withTaskGroup(of: ProcessedItem.self) { group in
    for item in items {
        group.addTask { await process(item) }
    }
    for await result in group {
        results.append(result)
    }
}

Swift 6 Migration Quick Guide

Key changes in Swift 6:

  • Strict concurrency checking enabled by default
  • Complete data-race safety at compile time
  • Sendable requirements enforced on boundaries
  • Isolation checking for all async boundaries

For detailed migration steps, see references/migration.md.

Reference Files

Load these files as needed for specific topics:

  • async-await-basics.md - async/await syntax, execution order, async let, URLSession patterns
  • tasks.md - Task lifecycle, cancellation, priorities, task groups, structured vs unstructured
  • threading.md - Thread/task relationship, suspension points, isolation domains, nonisolated
  • memory-management.md - Retain cycles in tasks, memory safety patterns
  • actors.md - Actor isolation, @MainActor, global actors, reentrancy, custom executors, Mutex
  • sendable.md - Sendable conformance, value/reference types, @unchecked, region isolation
  • linting.md - Concurrency-focused lint rules and SwiftLint async_without_await
  • async-sequences.md - AsyncSequence, AsyncStream, when to use vs regular async methods
  • core-data.md - NSManagedObject sendability, custom executors, isolation conflicts
  • performance.md - Profiling with Instruments, reducing suspension points, execution strategies
  • testing.md - XCTest async patterns, Swift Testing, concurrency testing utilities
  • migration.md - Swift 6 migration strategy, closure-to-async conversion, @preconcurrency, FRP migration

Best Practices Summary

  1. Prefer structured concurrency - Use task groups over unstructured tasks when possible
  2. Minimize suspension points - Keep actor-isolated sections small to reduce context switches
  3. Use @MainActor judiciously - Only for truly UI-related code
  4. Make types Sendable - Enable safe concurrent access by conforming to Sendable
  5. Handle cancellation - Check Task.isCancelled in long-running operations
  6. Avoid blocking - Never use semaphores or locks in async contexts
  7. Test concurrent code - Use proper async test methods and consider timing issues

Verification Checklist (When You Change Concurrency Code)

  • Confirm build settings (default isolation, strict concurrency, upcoming features) before interpreting diagnostics.
  • After refactors:
    • Run tests, especially concurrency-sensitive ones (see references/testing.md).
    • If performance-related, verify with Instruments (see references/performance.md).
    • If lifetime-related, verify deinit/cancellation behavior (see references/memory-management.md).

Glossary

See references/glossary.md for quick definitions of core concurrency terms used across this skill.

Note: This skill is based on the comprehensive Swift Concurrency Course by Antoine van der Lee.

© AFK-surf, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 15 other files (references) in .agents/skills/swift-concurrency of AFK-surf/OpenBridge.

  • SKILL.md
  • references/_index.md
  • references/actors.md
  • references/async-algorithms.md
  • references/async-await-basics.md
  • references/async-sequences.md
  • references/core-data.md
  • references/glossary.md
  • references/linting.md
  • references/memory-management.md
  • references/migration.md
  • references/performance.md
  • references/sendable.md
  • references/tasks.md
  • references/testing.md
  • references/threading.md

Open the folder on GitHubat commit a9ca905

Compare with similar skills

Swift Concurrency next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Swift Concurrency compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Swift Concurrency this skillAFK-surf/OpenBridge430—~2.8kAutomated safety check: PassMIT
Swift Concurrencysupabitapp/supaterm172—~3.3kAutomated safety check: PassCustom licence
Swift Concurrencyhenrypldev/react-native-nitro-mlx1003 repos~3.1kAutomated safety check: PassMIT
Dep Validateblokadaorg/blokada3.3k—~5.7kAutomated safety check: NotesMPL-2.0
cmux Swift Package Architecturemanaflow-ai/cmux28k1 repos~4.2kAutomated safety check: PassCustom licence
Python Prodavila7/claude-code-templates33k8 repos~1.8kAutomated safety check: PassMIT

Similar skills

  • Swift Concurrency

    supabitapp/supaterm

    Diagnose data races, convert callback-based code to async/await, implement actor isolation patterns, resolve Sendable conformance issues, and guide Swift 6 migration.

    172 GitHub stars~3.3k tokensUpdated 16 days ago
    DevelopmentAuto-check passed

  • Swift Concurrency

    henrypldev/react-native-nitro-mlx

    Diagnose Swift Concurrency issues, refactor callback-based code to async/await, and guide Swift 6 migration when working with tasks, actors, @MainActor, Sendable, data races, thread safety, or…

    100 GitHub starsUsed in 3 repos~3.1k tokens
    DevelopmentAuto-check passed

  • Dep Validate

    blokadaorg/blokada

    A skill your agent uses to validate risky dependency bumps end to end as a local or cloud-launched agent.

    3.3k GitHub stars~5.7k tokensUpdated yesterday
    DevelopmentAuto-check: notes

  • cmux Swift Package Architecture

    manaflow-ai/cmux

    Architecture rules for cmux's move to Swift Packages: acyclic whole-domain packages, minimal public API, group folders, Xcode project wiring and Swift 6 concurrency.

    28k GitHub starsUsed in 1 repo~4.2k tokens
    DevelopmentAuto-check passed

  • Python Pro

    davila7/claude-code-templates

    Master Python 3.12+ with modern features, async programming, performance optimization, and production-ready practices.

    33k GitHub starsUsed in 8 repos~1.8k tokens
    DevelopmentAuto-check passed

  • Swift Concurrency

    jamesrochabrun/skills

    Guide for building, auditing, and refactoring Swift code using modern concurrency patterns (Swift 6+).

    216 GitHub stars~1.9k tokensUpdated 8 mo ago
    DevelopmentAuto-check passed

More from AFK-surf/OpenBridge

All 14 skills in this repo

  • Swiftui UI Patterns

    AFK-surf/OpenBridge

    Best practices and example-driven guidance for building SwiftUI views and components.

    430 GitHub starsUsed in 4 repos~887 tokens
    Auto-check passed

  • Swiftui Expert Skill

    AFK-surf/OpenBridge

    Write, review, or improve SwiftUI code following best practices for state management, view composition, performance, modern APIs, Swift concurrency, and iOS 26+ Liquid Glass adoption.

    430 GitHub starsUsed in 2 repos~3.9k tokens
    Auto-check passed

  • UI Designer

    AFK-surf/OpenBridge

    Design or restyle user interfaces using vendored DESIGN.md references from popular product and brand-inspired visual systems.

    430 GitHub stars~4.6k tokensUpdated 4 mo ago
    Auto-check passed

  • Bridge Agent Log Analyzer

    AFK-surf/OpenBridge

    Analyze Bridge agent execution logs from ~/.bridge/sessions, reconstruct the agent's actual runtime behavior, and explain tool execution, failures, retries, and artifacts from persisted session files.

    430 GitHub stars~1.3k tokensUpdated 4 mo ago
    Auto-check passed

  • Format Converter

    AFK-surf/OpenBridge

    Convert files between formats. An agent skill from AFK-surf/OpenBridge.

    430 GitHub stars~549 tokensUpdated 4 mo ago
    Auto-check passed

  • Skill Manager

    AFK-surf/OpenBridge

    Manage skills: create, install, modify, or delete skills. An agent skill from AFK-surf/OpenBridge.

    430 GitHub stars~749 tokensUpdated 4 mo ago
    Auto-check passed

Works with

Categories

Questions about Swift Concurrency

What does Swift Concurrency do?

Expert guidance on Swift Concurrency best practices, patterns, and implementation. Swift Concurrency is an agent skill from AFK-surf/OpenBridge. Expert guidance on Swift Concurrency best practices, patterns, and implementation.

When should I use Swift Concurrency?

Swift Concurrency fits situations like: developers mention:; swift Concurrency; use Swift Concurrency; modern concurrency patterns.

How do I install Swift Concurrency in Claude Code?

Run `npx skills add AFK-surf/OpenBridge --skill swift-concurrency -a claude-code`. Or copy the skill folder (.agents/skills/swift-concurrency in AFK-surf/OpenBridge) into .claude/skills/swift-concurrency in your project. Claude Code loads it when a task matches its description.

How do I install Swift Concurrency in Codex?

Run `npx skills add AFK-surf/OpenBridge --skill swift-concurrency -a codex`. Or copy the skill folder (.agents/skills/swift-concurrency in AFK-surf/OpenBridge) into .agents/skills/swift-concurrency in your project. Codex loads it when a task matches its description.

Can I use Swift Concurrency in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add AFK-surf/OpenBridge --skill swift-concurrency -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/swift-concurrency, .gemini/skills/swift-concurrency, .github/skills/swift-concurrency and .opencode/skills/swift-concurrency in your project.

What does Swift Concurrency need to run?

SKILL.md names no scripts, command-line tools or credentials: Swift Concurrency is instructions for the agent only.

Does Swift Concurrency access the network?

SKILL.md names 1 domain. As links in the text: swiftconcurrencycourse.com. This is read from the text; nothing was executed.

Is Swift Concurrency safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Swift Concurrency use?

Swift Concurrency is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Swift Concurrency use?

About 2.8k tokens (SKILL.md is roughly 11k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 49k tokens, read only when the agent opens those files.

What are the alternatives to Swift Concurrency?

Skills that share tags, products or a category with Swift Concurrency: Swift Concurrency (supabitapp/supaterm, 172 stars), Swift Concurrency (henrypldev/react-native-nitro-mlx, 100 stars), Dep Validate (blokadaorg/blokada, 3.3k stars) and cmux Swift Package Architecture (manaflow-ai/cmux, 28k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Swift Concurrency?

AFK-surf (a GitHub organization) maintains it in AFK-surf/OpenBridge, which has 430 GitHub stars. The repository holds 14 skills in this directory. The repository was last updated on June 10, 2026.

Source: AFK-surf/OpenBridge on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.