swift-concurrency-expert

Swift Concurrency review and remediation for Swift 6.2+. Use when asked to review Swift Concurrency usage, improve concurrency compliance, or fix Swift concurrency compiler errors in a feature or file.

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npx tessl i github:Dimillian/Skills --skill swift-concurrency-expert

What are skills?

Review — 87%

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Validation — 11 / 11 Passed

Validation for skill structure

SKILL.md

Review

Evals

Evaluation results

100%

18%

Fix Concurrency Errors in a Swift 6.2 Document Export Feature

Isolated protocol conformance in approachable concurrency mode

Criteria

Without context

With context

Isolated conformance syntax

100%

No nonisolated workaround

100%

Minimal annotation changes

70%

100%

Global state on main actor

100%

No @unchecked Sendable

100%

Approachable concurrency mode noted

100%

Behavior preservation

100%

No Task.detached introduced

100%

Compiler diagnostics addressed

100%

Correct Swift version check

100%

Without context: $0.2206 · 1m · 8 turns · 9 in / 3,866 out tokens

With context: $0.2902 · 59s · 13 turns · 999 in / 3,002 out tokens

100%

21%

Optimize a Photo Thumbnail Generator to Stop Blocking the UI

Background offloading with @concurrent and nonisolated types

Criteria

Without context

With context

@concurrent attribute used

100%

Type is nonisolated

100%

Function is async

100%

await at call sites

100%

No Task.detached

100%

Main actor still guards UI state

100%

No @unchecked Sendable

100%

Smallest safe fix

40%

100%

No blocking main actor

100%

Without context: $0.5112 · 2m 51s · 12 turns · 13 in / 10,673 out tokens

With context: $0.3603 · 1m 3s · 17 turns · 1,004 in / 3,096 out tokens

96%

Fix Data-Race Errors in a SwiftUI Activity Ring Visualization

Sendable closure capture and global state protection

Criteria

Without context

With context

Value copy in capture list

80%

100%

No self capture in Sendable closure

100%

No @unchecked Sendable

100%

Global state @MainActor protected

100%

Immutable/value types preferred

70%

60%

SwiftUI View isolation preserved

100%

No Task.detached introduced

100%

Task used for async bridging

100%

Minimal annotation changes

100%

Behavior preservation

100%

Without context: $0.2523 · 1m 2s · 12 turns · 12 in / 3,507 out tokens

With context: $0.3390 · 59s · 16 turns · 74 in / 3,306 out tokens

Evaluated: 3 days ago
Agent: Claude Code

Table of Contents

Fix Concurrency Errors in a Swift 6.2 Document Export Feature Optimize a Photo Thumbnail Generator to Stop Blocking the UI Fix Data-Race Errors in a SwiftUI Activity Ring Visualization

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