Agent skill · software engineering · davila7
swift-concurrency-expert
Review and fix Swift concurrency issues such as actor isolation and Sendable violations.
Why this skill is useful
Provides specific guidance on fixing Swift concurrency issues that the AI wouldn't reliably generate on its own.
What it needs
About 2k tokens when loaded. Last updated 2026-08-06. 30,138 stars on the source repository.
What this skill does
Swift Concurrency Expert Overview Review and fix Swift Concurrency issues in Swift 6.2+ codebases by applying actor isolation, Sendable safety, and modern concurrency patterns with minimal behavior changes. When to Use When the user asks to review Swift concurrency usage or fix compiler diagnostics. When you need guidance on actor isolation, Sendable, @MainActor, or async migration. Workflow 1. Triage the issue Capture the exact compiler diagnostics and the offending symbol(s). Check project concurrency settings: Swift language version (6.2+), strict concurrency level, and whether approachable concurrency (default actor isolation / main-actor-by-default) is enabled. Identify the current actor context (@MainActor, actor, nonisolated) and whether a default actor isolation mode is enabled. Confirm whether the code is UI-bound or intended to run off the main actor. 2. Apply the smallest safe fix Prefer edits that preserve existing behavior while satisfying data-race safety. Common fixes: UI-bound types: annotate the type or relevant members with @MainActor. Protocol conformance on main actor types: make the conformance isolated (e.g., extension Foo: @MainActor SomeProtocol). Global/static state: protect with @MainActor or move into an actor. Background work: move expensive work into a @concurrent async function on a nonisolated type or use an actor to guard mutable state. Sendable errors: prefer immutable/value types; add Sendable conformance only when correct; avoid @unchecked Sendable unless you can prove thread safety. 3. Verify the fix Rebuild and confirm all concurrency diagnostics are resolved with no new warnings introduced. Run the test suite to check for regressions — concurrency changes can introduce subtle runtime issues even when the build is clean. If the fix surfaces new warnings, treat each one as a fresh triage (return to step 1) and resolve iteratively until the build is clean and tests pass. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills davila7/swift-concurrency-expert