swift-concurrency

First identify where the value crosses an isolation boundary, then either make the type Sendable, transfer it safely using region-based isolation, or restructure so the value never leaves its isolation domain. The skill's sendable and threading references cover Swift 6.2 behavior changes in detail.

Use an actor for shared mutable state in async contexts, @MainActor only for genuinely UI-related code like view models, and Mutex for synchronous fine-grained locking or legacy code integration. The skill includes a decision tree covering async versus synchronous contexts.

Add a new async method alongside the old one, replace completion handlers with return values or throws, and bridge remaining callback APIs with withCheckedContinuation or AsyncStream. The migration reference covers @preconcurrency and minimal-blast-radius strategies.

Swift 6 enables complete data-race safety at compile time, which surfaces Sendable and isolation diagnostics in older code. The skill recommends checking SWIFT_STRICT_CONCURRENCY and upcoming feature flags first, then migrating incrementally with small reviewable changes.

The warning fires when an async function contains no await calls. Remove async if it is not required; if it is required by a protocol, override, or @concurrent attribute, prefer a narrow suppression over adding fake awaits.

Yes, but NSManagedObject is not Sendable, so pass only NSManagedObjectID between contexts and use context.perform for access. The skill recommends a simple CoreDataStore pattern with @MainActor for the view context and @concurrent for background work over custom executors.