dart: Skill for Claude Code

.agents/skills/dart-build/SKILL.md

dart-build is a skill for Claude Code, Codex from dartsim/dart. It costs 18 tokens per session (646 once invoked), scanned A, original, BSD-2-Clause.

A build guide for the DART project, covering CMake, Pixi, dependencies, and troubleshooting. CMake prepares a project for compilation, while Pixi manages its environments and commands.

In plain words
What is it for?
Use it to configure and build DART, run its checks, manage dependencies, format code, and handle CUDA-specific build issues.
Why use it?
It helps diagnose missing tools, dependencies, configuration errors, and linking failures during development.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: reads .claude/ paths; installed under .agents/ (shared by several agents).

This is dartsim/dart's own configuration. It tells Claude Code and Codex how to work on dart itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything dart configures →

About the project

DART is an open-source C++23 physics engine that simulates the movement and interactions of articulated rigid-body systems for robotics, animation, and machine learning. Researchers and developers use it for kinematics, dynamics, collision handling, constraints, and loading robot models, with C++ and Python interfaces. The catalogue add-ons support workflows built around this engine.

dartsim/dart · 1,202 stars · on GitHub · dart.readthedocs.io

Reuse

Borrowing it

Nothing to install: this file belongs to dartsim/dart. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/dartsim/dart/main/.agents/skills/dart-build/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/dartsim/dart

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 dart-build

README.md
[![agentmods](https://agentmods.dev/badge/skills/dartsim/dart/dart-build.svg)](https://agentmods.dev/skills/dartsim/dart/dart-build)
Your own site
<a href="https://agentmods.dev/skills/dartsim/dart/dart-build"><img src="https://agentmods.dev/badge/skills/dartsim/dart/dart-build.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 646 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Agent Snooping · line 7
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
How audits are shown
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 $0.00018 $0.00646
Opus 5 $0.00009 $0.00323
Sonnet 5 $0.00004 $0.00129
Haiku 4.5 $0.00002 $0.00065

Measured 2d ago against content hash a57717073ef2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

dart-build 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 2d 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.

.agents/skills/dart-build/SKILL.md · 75 lines

How it starts

The opening of the file, as written. The whole thing — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DART Build System

Load this skill when working with DART's build system.

Quick Commands

pixi run config       # Configure CMake
pixi run build        # Build
pixi run test         # Run tests
pixi run test-all     # Full validation (lint + build + tests)
pixi run -e cuda test-all # CUDA-enabled full validation on Linux CUDA hosts
pixi run lint         # Format code

Full Documentation

For complete build instructions, read: docs/onboarding/building.md

For build system internals (CMake, dependencies): docs/onboarding/build-system.md

Common Issues

Issue Solution
CMake not found pixi install
Missing dependency Check pixi.toml
Build failure pixi run config then pixi run build
Linking error Check CMakeLists.txt in relevant module

CUDA Notes

  • On Linux hosts with visible NVIDIA GPUs, the CUDA Pixi config auto-detects compute capabilities for DART_CUDA_ARCHITECTURES; set DART_CUDA_ARCHITECTURES=<arch> only when overriding that detected list.
  • If CUDA runtime tests fail with unsupported PTX/toolchain errors, verify the generated CUDA flags include the local GPU architecture before assuming a kernel bug.

Pixi Lockfiles

  • Do not edit pixi.lock by hand. Change dependency constraints in pixi.toml, then run a Pixi command such as pixi install to let Pixi regenerate the lockfile.
  • If pixi.lock changes format or has broad solver churn, keep the generated output and call it out in the PR rather than attempting to splice lockfile entries manually.

Filament GUI Visual Checks

  • For Filament GUI, scene, or simulation rendering changes, load dart-verify-sim. Pair a text correctness oracle with agent-capture, view assessment, and claim-relevant engine debug layers; inspect the artifact and sidecar instead of relying only on command success.
  • If the user explicitly asks for the dartsim app, run pixi run dartsim and verify the requested interaction or behavior before ending the check. Then close any application you started solely for verification, unless the user asked to leave it running.

Read the full file on GitHub · 75 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. 2d ago Changed · +2 lines a57717073ef2
  2. 4d ago Changed 036243b56435
  3. 6d ago First seen · 73 lines · 18 tokens per session scan A 49f41dc1a47e

Subscribe to this mod's changes

dart-build is a skill published in the GitHub repository dartsim/dart (1,202 stars, last pushed yesterday), licensed BSD-2-Clause. It adds 18 tokens to every session and 646 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 2026-09-01.

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