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.
npx skills add Livsy90/iOS-Performance-Agent-Skills --skill swift-concurrency-performancegit clone --depth 1 https://github.com/Livsy90/iOS-Performance-Agent-SkillsWrote 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.
[](https://agentmods.dev/skills/livsy90/ios-performance-agent-skills/swift-concurrency-performance)<a href="https://agentmods.dev/skills/livsy90/ios-performance-agent-skills/swift-concurrency-performance"><img src="https://agentmods.dev/badge/skills/livsy90/ios-performance-agent-skills/swift-concurrency-performance/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/livsy90/ios-performance-agent-skills/swift-concurrency-performance"><img src="https://agentmods.dev/badge/skills/livsy90/ios-performance-agent-skills/swift-concurrency-performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00084 | $0.02283 |
| Opus 5 | $0.00042 | $0.01141 |
| Sonnet 5 | $0.00017 | $0.00457 |
| Haiku 4.5 | $0.00008 | $0.00228 |
Grade A, and why
swift-concurrency-performance 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 12d 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.
How it starts
The opening of the file, as written. The whole thing — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Swift Concurrency Performance
Purpose
Use this skill to review, diagnose, and improve Swift Concurrency code when async work affects UI responsiveness, throughput, memory, cancellation, task lifetime, actor contention, or correctness under load.
This skill is not a general Swift Concurrency tutorial. It is a performance and responsiveness review workflow.
When to use this skill
Use this skill when the task involves:
- UI stalls, slow interactions, hangs, or frame drops related to async work;
- excessive
Taskcreation, task groups, detached tasks, or unstructured concurrency; MainActorbottlenecks, actor hopping, actor queue buildup, or actor contention;- cancellation that does not stop work, navigation leaks, or tasks outliving their owner;
AsyncSequence,AsyncStream, long-running streams, buffering, or producer cleanup;- continuation bridges, delegate/callback wrappers, or async wrappers around legacy APIs;
- blocking calls inside async contexts, semaphores, synchronous I/O, locks, or cooperative pool starvation;
- actor reentrancy, duplicate in-flight work, cache stampedes, or inconsistent actor state after
await; - Swift 6 isolation behavior, explicit isolation,
@concurrent,nonisolated, or Sendable boundaries; - Instruments traces, logs, or production signals that point to concurrency-related latency, memory growth, or throughput loss.
When not to use this skill
Do not use this skill for:
- basic
async/awaitsyntax questions with no performance, lifetime, or responsiveness concern; - general architecture discussions where concurrency is not part of the critical path;
- purely SwiftUI rendering issues unless async lifecycle work contributes to the symptom;
- launch performance unless async startup work, task lifetime, or actor isolation is part of the launch path;
- runtime-level allocation, ARC, generics, or existential costs unless they interact with concurrency behavior;
- server-side concurrency questions unless the task is specifically about Swift Concurrency performance patterns.
What ships with it
12 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.
- agents/openai.yaml 328 B
- references/actor-reentrancy.md 18 KB
- references/asyncsequence-and-stream-cleanup.md 26 KB
- references/blocking-legacy-apis.md 20 KB
- references/bounded-task-groups.md 18 KB
- references/cancellation-and-task-lifetime.md 22 KB
- references/concurrency-runtime.md 22 KB
- references/continuation-safety.md 23 KB
- references/diagnostics-and-instruments.md 24 KB
- references/mainactor-responsiveness.md 24 KB
- references/swift-6-isolation.md 26 KB
- references/task-lifetime-and-structure.md 23 KB
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.
- 12d ago First seen · 149 lines · 84 tokens per session scan A 4cfea86e36e9
swift-concurrency-performance is a skill published in the GitHub repository Livsy90/iOS-Performance-Agent-Skills (113 stars, last pushed 2mo ago), licensed MIT. It adds 84 tokens to every session and 2,283 once invoked, about $0.0004 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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