Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add instructions/copperheadhq/copperhead/agents-mdgit clone --depth 1 https://github.com/copperheadhq/copperheadWhat 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 | $0.01073 | $0.01073 |
| Opus 5 | $0.00536 | $0.00536 |
| Sonnet 5 | $0.00215 | $0.00215 |
| Haiku 4.5 | $0.00107 | $0.00107 |
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 3d 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.
- 3d 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 (54 stars, last pushed 3d ago), licensed Apache-2.0. It adds 1,073 tokens to every session, about $0.0054 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 2026-08-30.
Other instructions, from other repositories
sortie copilot-instructions.md
Instructions for sortie-ai/sortie, covering sortie coding & review standards, 1. layered imports (downward only; violation is critical), 2. concurrency safety, 3. workspace path safety (critical: security boundary) and 4. persistence (sqlite).
sortie CLAUDE.md
Instructions for sortie-ai/sortie, covering sortie, commands, gotchas, boundaries and always.
chiplab AGENTS.md
Instructions for veecle/chiplab, covering agents.md, what is chiplab, 1. install / connect chiplab, 2. verify the connection and 3. pick the example for the board you want.
chiplab CLAUDE.md
Instructions for veecle/chiplab, a project described as: Give agents access to virtual hardware.
ii-agent AGENTS.md
Instructions for Intelligent-Internet/ii-agent, covering ii-agent contributor guide, quick start, repository map, mandatory rules and architecture.
kicad-happy GEMINI.md
Instructions for aklofas/kicad-happy, covering kicad-happy, agent guidelines, skills, running analysis and schematic analysis.