native-app-profiling

native-app-profiling is a skill for Claude Code, Codex from patrickserrano/lacquer. It costs 47 tokens per session (729 once invoked), scanned A, original, MIT.

A workflow for recording and analysing Instruments traces from native macOS and iOS apps. Instruments is Apple's tool for measuring CPU use, hangs, and UI delays.

In plain words
What is it for?
Use it to investigate CPU hotspots, app hangs, rendering hitches, and other native-app performance issues.
Why use it?
It turns performance traces into evidence about slow code paths and main-thread problems without requiring manual trace and symbol tools.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to investigate CPU hotspots, app hangs, rendering hitches, and other native-app performance issues.

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Install with agentmods
npx agentmods add skills/patrickserrano/lacquer/native-app-profiling
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.

Any agent
npx skills add patrickserrano/lacquer --skill native-app-profiling
Clone the repo
git clone --depth 1 https://github.com/patrickserrano/lacquer

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 native-app-profiling

README.md
[![agentmods](https://agentmods.dev/badge/skills/patrickserrano/lacquer/native-app-profiling.svg)](https://agentmods.dev/skills/patrickserrano/lacquer/native-app-profiling)
Your own site
<a href="https://agentmods.dev/skills/patrickserrano/lacquer/native-app-profiling"><img src="https://agentmods.dev/badge/skills/patrickserrano/lacquer/native-app-profiling.svg" alt="Measured on agentmods" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 729 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00047 $0.00729
Opus 5 $0.00023 $0.00365
Sonnet 5 $0.00009 $0.00146
Haiku 4.5 $0.00005 $0.00073

Measured 3d ago against content hash eb35e3a90f86, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

native-app-profiling 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 3d 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.

profiles/ios/skills/native-app-profiling/SKILL.md · 28 lines

How it starts

The opening of the file, as written. The whole thing — 28 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Native App Performance Profiling

This is a redirect skill. This lacquer's Instruments trace recording and analysis workflow lives in swiftui-expert-skill — see its "Record a new Instruments trace" and "Trace-driven improvement" task-workflow sections, backed by scripts/record_trace.py and scripts/analyze_trace.py and documented in full in references/trace-recording.md and references/trace-analysis.md. That workflow already covers everything this skill used to teach manually: template selection by device kind, attach/launch/stop-file recording modes, and analysis with automatic symbolication, window scoping, main-thread coverage (main_running_coverage_pct), and SwiftUI cause-graph fan-in (--fanin-for).

Do not use raw xcrun xctrace, atos, vmmap, or pgrep for this. FlowDeck's ban on raw Apple CLI tools (xcodebuild, xcrun, simctl, devicectl) extends to Instruments tooling in this lacquer for the same reason — record_trace.py/analyze_trace.py wrap xctrace and handle symbolication automatically, so the manual atos/vmmap load-address dance this skill used to document is no longer part of the workflow.

When this applies

Any request to profile CPU usage, find performance hotspots, or diagnose hangs/hitches in a native iOS/macOS app — whether or not the code under investigation is SwiftUI. swiftui-expert-skill's trace workflow is not SwiftUI-specific for recording or the Time Profiler/Hangs/Animation Hitches lanes: only the swiftui and swiftui-causes analysis lanes are SwiftUI-specific, and they simply report available: false on non-SwiftUI code paths.

Gotchas not covered elsewhere

These are the two items from the old manual workflow that remain relevant and aren't already documented in swiftui-expert-skill's trace references:

  • Idle time produces empty data. Trigger the slow code path during the recording window — profiling an idle app yields empty or low-signal traces regardless of capture duration.
  • Instruments permissions. xctrace (wrapped by record_trace.py) may prompt for Developer Tools access or Full Disk Access on first use on a given machine, or require elevated privileges for certain system-wide captures. This is separate from the per-device signing/trust failure mode already documented in references/trace-recording.md.

Read the full file on GitHub · 28 lines

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. 3d ago First seen · 28 lines · 47 tokens per session scan A eb35e3a90f86

Subscribe to this mod's changes

native-app-profiling is a skill published in the GitHub repository patrickserrano/lacquer (3 stars, last pushed yesterday), licensed MIT. It adds 47 tokens to every session and 729 once invoked, about $0.0002 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 2026-09-03.

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