Borrowing it
Nothing to install: this file belongs to copperheadhq/copperhead. 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/copperheadhq/copperhead/main/AGENTS.mdgit clone --depth 1 https://github.com/copperheadhq/copperheadWrote 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/copperheadhq/copperhead/agents-md)<a href="https://agentmods.dev/instructions/copperheadhq/copperhead/agents-md"><img src="https://agentmods.dev/badge/instructions/copperheadhq/copperhead/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/copperheadhq/copperhead/agents-md"><img src="https://agentmods.dev/badge/instructions/copperheadhq/copperhead/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 | $0.01124 | $0.01124 |
| Opus 5.5 | $0.00450 | $0.00450 |
| Sonnet 5.5 | $0.00225 | $0.00225 |
| Haiku 4.5 | $0.00112 | $0.00112 |
Grade A, and why
copperhead 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 14d 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 — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md
This file provides repository guidance for Codex and other coding agents. Claude Code users also have CLAUDE.md; keep shared architectural and verification guidance aligned between the two files.
Repository overview
copperhead is a TypeScript CLI agent for designing and editing real KiCad projects. It edits .kicad_sch and .kicad_pcb s-expression files, keeps design documentation synchronized, and verifies changes with kicad-cli. The package is ESM-only, requires Node.js 20 or newer, and is licensed under Apache-2.0.
Phase 1 is implemented. Deterministic commands and the offline test suite are the proven path; live agent-loop acceptance tests require model API keys and must not be described as passing unless they were actually run.
Sources of truth
- Read
openspec/specs/SPEC.mdbefore making architectural or behavior changes. It defines the product, CLI, agent loop, tool contracts, configuration, safety rails, and acceptance criteria. - The active Phase 1 artifacts are in
openspec/changes/build-copperhead-phase-1/:proposal.md,design.md, capability specs, andtasks.md. - The planned part-research work is separate and lives in
openspec/changes/add-part-research-tools/; do not implement it incidentally. - When behavior changes at the specification level, update
openspec/specs/SPEC.mdand the applicable change artifacts together.
Build and verification
Use these commands from the repository root:
npm install
npm run typecheck
npm test
npm run build
npm run docs:build
Run the narrowest relevant tests while iterating, then run npm run typecheck and npm test before considering a code change complete. Run npm run build for CLI or packaging changes and npm run docs:build for documentation-site changes.
Tests that touch a live LLM are in test/agent-integration.test.ts. Direct providers require OPENAI_API_KEY or ANTHROPIC_API_KEY; the saved-login Codex path is opt-in with COPPERHEAD_TEST_CODEX=1. Never add credentials to the repository or transcripts merely to make these tests run.
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.
- 14d ago Changed · +51 tokens per session 90feece049bd
- 2mo ago First seen · 81 lines · 1,073 tokens per session scan A 3bc545e8bdc6
copperhead AGENTS.md is an instructions file published in the GitHub repository copperheadhq/copperhead (666 stars, last pushed yesterday), licensed Apache-2.0. It adds 1,124 tokens to every session, about $0.0045 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).
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.