Project CHRONO is an open-source C++ library for modeling and simulating physical systems such as connected rigid bodies, deformable bodies, granular materials, fluids, vehicles, and robots. It is used for multiphysics, multibody dynamics, robotics, autonomous-agent, and related engineering simulations.
Borrowing it
Nothing to install: this file belongs to projectchrono/chrono. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/projectchrono/chrono/main/AGENTS.mdgit clone --depth 1 https://github.com/projectchrono/chronoWrote 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/instructions/projectchrono/chrono/agents-md)<a href="https://agentmods.dev/instructions/projectchrono/chrono/agents-md"><img src="https://agentmods.dev/badge/instructions/projectchrono/chrono/agents-md/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/instructions/projectchrono/chrono/agents-md"><img src="https://agentmods.dev/badge/instructions/projectchrono/chrono/agents-md.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 | $0.02011 | $0.02011 |
| Opus 5.5 | $0.00804 | $0.00804 |
| Sonnet 5.5 | $0.00402 | $0.00402 |
| Haiku 4.5 | $0.00201 | $0.00201 |
Grade A, and why
chrono AGENTS.md 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 1mo 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 — 56 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Repository Guidelines
Developers vs. Users
Chrono serves two audiences. Developers modify this repository itself: core libraries, modules, demos, tests, and docs. Users often work in an external repository, build and install Chrono locally, then link against it from their own CMake project. Keep this distinction explicit in your response. Shared guidance below applies to both groups; commit and pull request guidance applies only to developers.
Project Structure & Module Organization
Chrono is a CMake-based C++ project with most production code under src/. Core code lives in src/chrono, optional modules live in sibling directories such as src/chrono_vehicle, src/chrono_sensor, and src/chrono_ros, and examples live in src/demos. C++ unit tests are under src/tests/unit_tests, Python tests under src/tests/unit_tests/python, runtime assets under data/, and API/tutorial docs under doxygen/. Use contrib/ for build helpers, packaging, and Docker files. Keep new code near the owning module and update the local CMakeLists.txt in that directory.
Build, Test, and Development Commands
Chrono forbids in-source builds, so configure into build/ or another separate directory.
git submodule init && git submodule update: fetch the bundled third-party sources. There are five, and a missing one surfaces as a confusing configure error:googletest(unit tests),googlebenchmark(benchmark tests),flatbuffers(Chrono::SynChrono),fmu-forge(Chrono::FMI), andSEA-Stack(Chrono::FSI, TDPF solver).cmake -S . -B build -G Ninja -DBUILD_TESTING=ON -DBUILD_DEMOS=ON: configure a local development build.cmake --build build -j: compile the configured targets.ctest --test-dir build --output-on-failure: run the registered CTest suite.cmake --build build --target install: install into the configured prefix.CMakePresets.jsoncarries the CI configurations (linuxci-amd64,linuxci-arm64,macosci,windowsci-vs2022). Use--preset=<name>to reproduce a CI build locally rather than reconstructing its options by hand.
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.
- 1mo ago Changed · -1 tokens per session 6470157e6c3c
- 2mo ago Changed · +10 lines · +691 tokens per session 2b6d02da3d1b
- 2mo ago First seen · 46 lines · 1,321 tokens per session scan A 48fddffde027
chrono AGENTS.md is an instructions file published in the GitHub repository projectchrono/chrono (3,140 stars, last pushed yesterday), licensed BSD-3-Clause. It adds 2,011 tokens to every session, about $0.0080 per session on Opus 5.5. 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.
chrono AGENTS.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| chrono AGENTS.mdprojectchrono/chrono | Instructions file | 3.1k | yesterday | BSD-3-Clause | A | 2,011 | Codex, OpenCode |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 9,719 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | yesterday | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | yesterday | MIT | A | 4,680 | Codex, OpenCode |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 5,516 | GitHub Copilot |
| vscode copilot-instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 3,093 | GitHub Copilot |
| deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness | Instructions file | 274k | 2d ago | MIT | A | 4,313 | Codex, OpenCode |