swift-concurrency-expert

swift-concurrency-expert is a skill for Claude Code, Codex from steipete/agent-scripts. It costs 22 tokens per session (390 once invoked), scanned A, original, MIT.

A review and repair skill for Swift 6.2+ concurrency problems, including compiler errors involving Sendable and actor isolation.

In plain words
What is it for?
Use it to inspect concurrency diagnostics and apply fixes such as MainActor annotations, actors, Sendable changes, and safer background work.
Why use it?
It helps resolve data-race safety issues while keeping the existing behavior of the code as unchanged as possible.

Skill for Claude CodeCodex

About the project

Agent Scripts is a repository of shared instructions, reusable skills, helper scripts, and local safeguards for coding-agent workflows across multiple workspaces. It is for maintaining common agent behavior and portable development utilities between repositories.

steipete/agent-scripts · 6,598 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/steipete/agent-scripts/swift-concurrency-expert
Any agent
npx skills add steipete/agent-scripts --skill swift-concurrency-expert
Clone the repo
git clone --depth 1 https://github.com/steipete/agent-scripts

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for swift-concurrency-expert

README.md
[![agentmods](https://agentmods.dev/badge/skills/steipete/agent-scripts/swift-concurrency-expert.svg)](https://agentmods.dev/skills/steipete/agent-scripts/swift-concurrency-expert)
Your own site
<a href="https://agentmods.dev/skills/steipete/agent-scripts/swift-concurrency-expert"><img src="https://agentmods.dev/badge/skills/steipete/agent-scripts/swift-concurrency-expert.svg" alt="Measured on agentmods" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 390 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00022 $0.00390
Opus 5 $0.00011 $0.00195
Sonnet 5 $0.00004 $0.00078
Haiku 4.5 $0.00002 $0.00039

Measured 5d ago against content hash eaf45b132872, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

swift-concurrency-expert scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/swift-concurrency-expert/SKILL.md · 38 lines

What it actually says

Swift Concurrency Expert

Attribution: copied from @Dimillian’s Dimillian/Skills (2025-12-31).

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.

Workflow

1. Triage the issue

  • Capture the exact compiler diagnostics and the offending symbol(s).
  • 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.

Reference material

  • See references/swift-6-2-concurrency.md for Swift 6.2 changes, patterns, and examples.
  • See references/swiftui-concurrency-tour-wwdc.md for SwiftUI-specific concurrency guidance.
Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 38 lines · 22 tokens per session scan A eaf45b132872

Subscribe to this mod's changes

swift-concurrency-expert is a skill published in the GitHub repository steipete/agent-scripts (6,598 stars, last pushed today), licensed MIT. It adds 22 tokens to every session and 390 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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