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.
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:
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.
Swift 6 concurrency patterns → /skill axiom-swift-concurrency
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
| 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