Borrowing it
Nothing to install: this file belongs to Codename-11/ARC. 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/Codename-11/ARC/master/AGENTS.mdgit clone --depth 1 https://github.com/Codename-11/ARCWrote 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/codename-11/arc/agents-md)<a href="https://agentmods.dev/instructions/codename-11/arc/agents-md"><img src="https://agentmods.dev/badge/instructions/codename-11/arc/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/codename-11/arc/agents-md"><img src="https://agentmods.dev/badge/instructions/codename-11/arc/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 | $0.03620 | $0.03620 |
| Opus 5.5 | $0.01448 | $0.01448 |
| Sonnet 5.5 | $0.00724 | $0.00724 |
| Haiku 4.5 | $0.00362 | $0.00362 |
Grade A, and why
ARC 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.
This is a copy
88% identical to SubFrame AGENTS.md — 41 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 387 lines — stays where its author put it; the contents beside it link to each section on GitHub.
ARC - SubFrame Project
This project is managed with SubFrame. AI assistants should follow the rules below to keep documentation up to date.
Note: This file is named
AGENTS.mdto be AI-tool agnostic. CLAUDE.md and GEMINI.md contain a reference to this file.
Core Working Principle
Only do what the user asks. Do not go beyond the scope of the request.
- Implement exactly what the user requested — nothing more, nothing less.
- Do not change business logic, flow, or architecture unless the user explicitly asks for it.
- If a user asks for a design change, only change the design. Do not refactor, restructure, or modify functionality alongside it.
- If you have additional suggestions or improvements, present them as suggestions to the user. Never implement them without approval.
- The user's request must be completed first. Additional ideas come after, as proposals.
Relationship to Native AI Tools
SubFrame enhances native AI coding tools — it does not replace them.
Claude Code works exactly as normal. Built-in features (/init, /commit, /review-pr, /compact, /memory, CLAUDE.md) are fully supported. CLAUDE.md is Claude Code's native instruction file — users can add their own tool-specific instructions freely. SubFrame adds a small backlink reference pointing to this AGENTS.md file using HTML comment markers (<!-- SUBFRAME:BEGIN --> / <!-- SUBFRAME:END -->). SubFrame will never overwrite user content in CLAUDE.md.
Gemini CLI works exactly as normal. Built-in features (/init, /model, /memory, /compress, /settings, GEMINI.md) are fully supported. GEMINI.md is Gemini CLI's native instruction file — same backlink approach as CLAUDE.md. Users can add their own instructions freely and SubFrame won't overwrite them.
Codex CLI gets SubFrame context via a wrapper script at .subframe/bin/codex that injects AGENTS.md as an initial prompt.
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 · 387 lines · 3,620 tokens per session scan A 58badfd9328d
ARC AGENTS.md is an instructions file published in the GitHub repository Codename-11/ARC (4 stars, last pushed 4mo ago), licensed MIT. It adds 3,620 tokens to every session, about $0.0145 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 88% identical to SubFrame AGENTS.md, differing in 41 lines, and is treated as a copy.
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).
vscode model-prompts.instructions.md
Model-specific prompt authoring and registry guidelines.