What is cairn AGENTS.md?

Project instructions for the Cairn codebase, stored in an AGENTS.md file. They describe shared rules for coding agents and how an agent manager should receive reports.

Following Cairn’s repository instructions and reporting progress or results to its agent manager.

They give coding agents the project-specific guidance needed to work consistently in that repository. The description does not provide the individual rules.

How johnmontejano/cairn configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to johnmontejano/cairn. 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/johnmontejano/cairn/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/johnmontejano/cairn

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/johnmontejano/cairn/agents-md/github.svg)](https://agentmods.dev/instructions/johnmontejano/cairn/agents-md)

Your own site

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

Per session 591 This file is loaded in full into every session.

When invoked 591 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 unknown 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	$0.00591	$0.00591
Opus 5.5	$0.00236	$0.00236
Sonnet 5.5	$0.00118	$0.00118
Haiku 4.5	$0.00059	$0.00059

Measured 2mo ago against content hash d876be116442, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cairn 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 · 60 lines

The source is not reproduced here

No licence file

Read it on GitHub

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 · 60 lines · 591 tokens per session scan A d876be116442

Subscribe to this mod's changes

cairn AGENTS.md is an instructions file published in the GitHub repository johnmontejano/cairn (0 stars, last pushed 2mo ago), with no licence file. It adds 591 tokens to every session, about $0.0024 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 2026-08-31.

cairn AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
cairn AGENTS.mdjohnmontejano/cairn	Instructions file	0	2mo ago	none	A	591	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

cairn: Instructions file for Codex