Borrowing it
Nothing to install: this file belongs to layoutit/polycss. 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/layoutit/polycss/main/AGENTS.mdgit clone --depth 1 https://github.com/layoutit/polycssWrote 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/layoutit/polycss/agents-md)<a href="https://agentmods.dev/instructions/layoutit/polycss/agents-md"><img src="https://agentmods.dev/badge/instructions/layoutit/polycss/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/layoutit/polycss/agents-md"><img src="https://agentmods.dev/badge/instructions/layoutit/polycss/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 | $0.18674 | $0.18674 |
| Opus 5.5 | $0.07470 | $0.07470 |
| Sonnet 5.5 | $0.03735 | $0.03735 |
| Haiku 4.5 | $0.01867 | $0.01867 |
Grade A, and why
polycss 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 — 431 lines — stays where its author put it; the contents beside it link to each section on GitHub.
PolyCSS — agent guide
This file is the single source of truth for AI coding agents (Claude Code, Cursor, etc.). CLAUDE.md is a symlink to this file — always edit AGENTS.md, never CLAUDE.md. The constraints below describe the current design and the rules we work under; if a request conflicts with one of them, push back before doing it.
What this repo is
PolyCSS is a CSS-based polygon mesh rendering engine. It paints 3D meshes by emitting one DOM element per polygon, transforming it with matrix3d, and letting the browser composite the result. No WebGL, no canvas-per-frame. Rasterisation only happens once, into a texture atlas; everything after that is pure DOM + CSS.
Monorepo layout (pnpm workspaces):
| Package | npm name | Role |
|---|---|---|
packages/core |
@layoutit/polycss-core |
Pure math: Vec3, Polygon, scene, camera, mesh ops, atlas planning. Zero browser globals (lib: ES2020 only). |
packages/polycss |
@layoutit/polycss |
Vanilla renderer + custom elements (<poly-scene>, etc.). Owns DOM emission, CSS injection, its own copy of atlas rasterisation. Depends on core only. |
packages/react |
@layoutit/polycss-react |
React components + hooks. Owns its own copy of atlas rasterisation. Depends on core only — NOT on polycss. |
packages/vue |
@layoutit/polycss-vue |
Vue 3 mirror of the React package. Owns its own copy of atlas rasterisation. Depends on core only. |
packages/fonts |
@layoutit/polycss-fonts |
Fonts + text → extruded 3D Polygon[]. Hand-written TrueType (glyf) reader + extruder (flat/round/bevel profiles) + Google Fonts loader. Framework-agnostic (returns Polygon[], no React/Vue mirror needed). Depends on core + earcut. |
packages/morph |
@layoutit/polycss-morph |
Framework-agnostic prepared-model contracts, deterministic Node preparation, browser loading, retained DOM mounting, sparse deformation, controls, springs, animation, joint skinning, and prepared playback. The browser entry uses public @layoutit/polycss APIs; Node-only preparation lives at @layoutit/polycss-morph/prepare. No React/Vue mirrors. |
packages/domformat |
@layoutit/polycss-domformat |
Private strict-TypeScript domformat@0 writer, reader, validator, CLI, and browser mount with repository-side conformance. Its closed retained-DOM runtime includes sparse playback/surface/variants, typed atlas positions, responsive prepared presentation/layout/timeline profiles, host-selected prepared-bank handoff, fixed orbit input, one bounded digest-bound page lifecycle shared by paged transform/visibility playback and paged variants, and compositor-owned linear transform timing. It owns the producer-neutral wire contract; producer lowering and product input policy stay in producer/host packages. Runtime installs contain code-split ESM and declarations but exclude certification material. Not published. |
packages/skills |
@layoutit/polycss-skills |
Zero-dependency npx installer for the PolyCSS agent skill. Owns skill/SKILL.md + skill/docs/*.md — the source of truth for what agents are told about PolyCSS. No renderer code, no runtime dependency on any other package. |
website |
@layoutit/polycss-website |
Astro + Starlight docs site. Not published. |
examples/{html,vanilla,react,vue,fontcss} |
private | Per-framework Vite apps demonstrating the minimal usage for each renderer (fontcss demos @layoutit/polycss-fonts). Workspace members so they resolve to local workspace:^ packages. Not published. |
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 First seen · 431 lines · 18,674 tokens per session scan A b4109b1ea8e1
polycss AGENTS.md is an instructions file published in the GitHub repository layoutit/polycss (771 stars, last pushed 2mo ago), licensed MIT. It adds 18,674 tokens to every session, about $0.0747 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.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deno copilot-instructions.md
Copilot instructions for denoland/deno, covering deno development guide for github copilot, network access, high level overview, key directories and key files to understand first.