Use when writing ANY code with async, actors, threads, or seeing ANY concurrency error. Covers Swift 6 concurrency, @MainActor, Sendable, data races, async/await patterns, performance optimization.
Generates Swift concurrency solutions for async/await patterns, actor isolation, data races, and Swift 6 migration.
npx claudepluginhub charleswiltgen/axiomThis skill inherits all available tools. When active, it can use any tool Claude has access to.
You MUST use this skill for ANY concurrency, async/await, threading, or Swift 6 concurrency work.
Use this router when:
ios-concurrency vs ios-performance: When app freezes or feels slow:
ios-concurrency vs ios-build: When seeing Swift 6 concurrency errors:
ios-concurrency vs ios-data: When concurrency errors involve Core Data or SwiftData:
Rationale: A 2-second freeze during data loading is almost always await on main thread or missing background dispatch. Domain knowledge solves this faster than Time Profiler. Core Data threading violations need Core Data-specific fixes, not generic concurrency patterns.
Swift 6 concurrency patterns → /skill axiom-swift-concurrency
Swift concurrency API reference → /skill axiom-swift-concurrency-ref
Swift performance → /skill axiom-swift-performance
Synchronous actor access → /skill axiom-assume-isolated
Thread-safe primitives → /skill axiom-synchronization
Parameter ownership → /skill axiom-ownership-conventions
Concurrency profiling → /skill axiom-concurrency-profiling
Concurrency audit → Launch concurrency-auditor agent or /axiom:audit concurrency (Swift 6 strict concurrency violations, unsafe Task captures, missing @MainActor, Sendable violations, actor isolation problems)
| Thought | Reality |
|---|---|
| "Just add @MainActor and it'll work" | @MainActor has isolation inheritance rules. swift-concurrency covers all patterns. |
| "I'll use nonisolated(unsafe) to silence the warning" | Silencing warnings hides data races. swift-concurrency shows the safe pattern. |
| "It's just one async call" | Even single async calls have cancellation and isolation implications. swift-concurrency covers them. |
| "I know how actors work" | Actor reentrancy and isolation rules changed in Swift 6.2. swift-concurrency is current. |
| "I'll fix the Sendable warnings later" | Sendable violations cause runtime crashes. swift-concurrency fixes them correctly now. |
Swift 6 Concurrency (swift-concurrency):
Swift Performance (swift-performance):
User: "I'm getting 'data race' errors in Swift 6"
→ Invoke: /skill axiom-swift-concurrency
User: "How do I use @MainActor correctly?"
→ Invoke: /skill axiom-swift-concurrency
User: "My app is slow due to unnecessary copying"
→ Invoke: /skill axiom-swift-performance
User: "Should I use async/await for this network call?"
→ Invoke: /skill axiom-swift-concurrency
User: "How do I use assumeIsolated?"
→ Invoke: /skill axiom-assume-isolated
User: "My delegate callback runs on main thread, how do I access MainActor state?"
→ Invoke: /skill axiom-assume-isolated
User: "Should I use Mutex or actor?"
→ Invoke: /skill axiom-synchronization
User: "What's the difference between os_unfair_lock and OSAllocatedUnfairLock?"
→ Invoke: /skill axiom-synchronization
User: "What does borrowing do in Swift?"
→ Invoke: /skill axiom-ownership-conventions
User: "How do I use ~Copyable types?"
→ Invoke: /skill axiom-ownership-conventions
User: "My async code is slow, how do I profile it?"
→ Invoke: /skill axiom-concurrency-profiling
User: "I think I have actor contention, how do I diagnose it?"
→ Invoke: /skill axiom-concurrency-profiling
User: "My Core Data saves lose data from background tasks"
→ Route to: ios-data router (Core Data threading is framework-specific)
User: "How do I create a TaskGroup?"
→ Invoke: /skill axiom-swift-concurrency-ref
User: "What's the AsyncStream API?"
→ Invoke: /skill axiom-swift-concurrency-ref
User: "How do I create a custom global actor?"
→ Invoke: /skill axiom-swift-concurrency-ref
User: "How do I convert a completion handler to async?"
→ Invoke: /skill axiom-swift-concurrency-ref
User: "What are the actor reentrancy rules?"
→ Invoke: /skill axiom-swift-concurrency-ref
User: "Check my code for Swift 6 concurrency issues"
→ Invoke: concurrency-auditor agent
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