profile-dart-code

profile-dart-code is a skill for Claude Code, Codex from kevmoo/dash_skills. It costs 53 tokens per session (830 once invoked), scanned A, original, Apache-2.0.

A profiling skill for Dart command-line programs. It uses Dart's VM Service to record CPU activity and show which functions use the most execution time.

In plain words
What is it for?
Use it to investigate slow Dart scripts, hot loops, expensive function calls, object allocation, hashing, or virtual dispatch.
Why use it?
It helps locate performance bottlenecks without opening a browser or using DevTools.

Skill for Claude CodeCodex

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/kevmoo/dash_skills/profile-dart-code
Any agent
npx skills add kevmoo/dash_skills --skill profile-dart-code
Clone the repo
git clone --depth 1 https://github.com/kevmoo/dash_skills

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 profile-dart-code

README.md
[![agentmods](https://agentmods.dev/badge/skills/kevmoo/dash_skills/profile-dart-code.svg)](https://agentmods.dev/skills/kevmoo/dash_skills/profile-dart-code)
Your own site
<a href="https://agentmods.dev/skills/kevmoo/dash_skills/profile-dart-code"><img src="https://agentmods.dev/badge/skills/kevmoo/dash_skills/profile-dart-code.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 830 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 $0.00053 $0.00830
Opus 5 $0.00026 $0.00415
Sonnet 5 $0.00011 $0.00166
Haiku 4.5 $0.00005 $0.00083

Measured 5d ago against content hash 17760386a034, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

profile-dart-code 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.

skills/profile-dart-code/SKILL.md · 83 lines

How it starts

The opening of the file, as written. The whole thing — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Dart CPU Profiling

Guidelines and automated tools for capturing CPU profiles and identifying bottlenecks in Dart command-line applications.

When to use this skill

  • When asked to profile, optimize, or benchmark CPU execution of a Dart script or CLI tool.
  • When investigating hot loops, heavy function calls, or unexpected execution overhead.

Workflow

  1. Ensure clean compilation: Make sure the target Dart script runs cleanly (dart run <script.dart>).
  2. Run Profiler Script: Use the automated profiling helper script inside this skill directory to launch the target app with VM Service observability enabled, capture CPU samples, and output top-consuming functions.
  3. Analyze & Optimize: Review the self and total sample percentages reported by the tool to pinpoint bottlenecks (e.g., excessive object allocation, costly hashing, virtual dispatch overhead).

Running the Profiler Helper Script

This repository includes a zero-dependency (using only official vm_service) profiling script that launches any Dart file, connects to the VM Service, waits for execution to complete (--pause-isolates-on-exit), retrieves CPU samples, and prints a clean summary while exporting the full JSON profile.

Run it from any working directory:

dart run <dash_skills_repo>/skills/profile-dart-code/scripts/bin/profile.dart --out=cpu_profile.json -- <path_to_target.dart> [target_arguments...]

Script Arguments

  • -o, --out=<file>: Output file path to save the raw JSON CPU profile (default: cpu_profile.json).
  • -p, --period=<micros>: Sampling interval in microseconds (default: 1000µs = 1ms). Minimum 50µs.
  • -- <target.dart> [args...]: The Dart script to profile, followed by any arguments passed to main().

[!WARNING] Potential Hangs: When profiling or debugging Dart targets using VM services, target exceptions or connection issues can cause the process to hang indefinitely. Ensure your target script handles timeouts, and monitor the process output.

Read the full file on GitHub · 83 lines

Files

What ships with it

3 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 · 83 lines · 53 tokens per session scan A 17760386a034

Subscribe to this mod's changes

profile-dart-code is a skill published in the GitHub repository kevmoo/dash_skills (144 stars, last pushed 5d ago), licensed Apache-2.0. It adds 53 tokens to every session and 830 once invoked, about $0.0003 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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