What is brometal AGENTS.md?

A project guide for coding agents working on BroMetal, a software library for writing GPU shader programs, plus its website.

Use it when changing BroMetal's compiler, runtime, shader functions, geometry tools, tests, or website examples.

It gives agents the repository layout, important package boundaries, and the commands used to test, type-check, build, and run the website.

How ericdrowell/brometal configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to ericdrowell/brometal. 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/ericdrowell/brometal/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/ericdrowell/brometal

Made for: Codex, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/ericdrowell/brometal/agents-md/github.svg)](https://agentmods.dev/instructions/ericdrowell/brometal/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/ericdrowell/brometal/agents-md"><img src="https://agentmods.dev/badge/instructions/ericdrowell/brometal/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/ericdrowell/brometal/agents-md"><img src="https://agentmods.dev/badge/instructions/ericdrowell/brometal/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 953 This file is loaded in full into every session.

When invoked 953 The same file — it is already loaded in full.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00953	$0.00953
Opus 5.5	$0.00381	$0.00381
Sonnet 5.5	$0.00191	$0.00191
Haiku 4.5	$0.00095	$0.00095

Measured 2mo ago against content hash d89d2918413b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

brometal 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 2mo 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.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

BroMetal — notes for coding agents working on this repo

If you are writing an app that uses BroMetal, read packages/brometal/AGENTS.md instead — it covers the DSL rules and the failure modes. This file is about the codebase itself.

Layout

packages/brometal/     the library: compiler, runtimes, shader-function library
  src/compiler/        parse → analyze → ir → optimize → emit-glsl / emit-wgsl
  src/runtime/         context, program, uniforms, texture, render-target, loop
  src/dsl/             the types and builtin stubs the DSL is written against
  src/shader-functions/  library-source.ts (GPU source) + index.ts (typed decls)
  src/geometries/      parametric mesh generators
  tests/               vitest, no browser
packages/website/      Next.js site (brometal.dev): home, examples, SEO routes
  src/shaders/         *.shader.ts + generated *.shader.gen.ts
  src/demos/           one client component per example

Commands

npm test                       # vitest, from the repo root
npm run typecheck              # both packages
npm run build                  # build the library (writes packages/brometal/dist)
npm run dev:website            # site on :3005

# inside packages/website
npm run shaders                # compile *.shader.ts with the LOCAL compiler

Use npm run shaders, not npx brometal. The website has a brometal-published dependency (the released package, used to verify prod builds), and npx brometal resolves to that — so your local compiler changes appear to do nothing. npm run shaders points at ../brometal/dist.

Rebuild the library before recompiling website shaders. The CLI runs from dist, so a change to src/compiler needs npm run build first.

Adding a shader function

Two files, kept in step:

src/shader-functions/library-source.ts — the GPU source, as a string, with a deps array naming any other library functions it calls. Dependencies are pulled in automatically and tree-shaken if unused.
src/shader-functions/index.ts — the typed declaration plus a gpuOnly(...) body, so calling it on the CPU throws with a useful message.

Read the full file on GitHub · 85 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.

2mo ago First seen · 85 lines · 953 tokens per session scan A d89d2918413b

Subscribe to this mod's changes

brometal AGENTS.md is an instructions file published in the GitHub repository ericdrowell/brometal (107 stars, last pushed 1mo ago), licensed MIT. It adds 953 tokens to every session, about $0.0038 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.

TypeScript compiler shaders webgpu

brometal AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
brometal AGENTS.mdericdrowell/brometal	Instructions file	107	1mo ago	MIT	A	953	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

brometal: Instructions file for Codex