btw: Instructions file for Codex

AGENTS.md

btw AGENTS.md is an instructions file for Codex, OpenCode from posit-dev/btw. It costs 3,690 tokens per session, scanned A, original, no licence file.

A project instruction file for btw, including its purpose, quick reference, design philosophy, key decisions, and how it works.

In plain words
What is it for?
It helps an agent understand btw's structure, intended use, and important implementation decisions.
Why use it?
It gives a coding agent the background and project rules needed to make informed changes to btw.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md.

This is posit-dev/btw's own configuration. It tells Codex and OpenCode how to work on btw itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything btw configures →

Reuse

Borrowing it

Nothing to install: this file belongs to posit-dev/btw. 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/posit-dev/btw/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/posit-dev/btw

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.

agentmods badge for btw AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/posit-dev/btw/agents-md/github.svg)](https://agentmods.dev/instructions/posit-dev/btw/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/posit-dev/btw/agents-md"><img src="https://agentmods.dev/badge/instructions/posit-dev/btw/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.

agentmods 80×15 button for btw AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/posit-dev/btw/agents-md"><img src="https://agentmods.dev/badge/instructions/posit-dev/btw/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 3,690 This file is loaded in full into every session.
When invoked 3,690 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.03690 $0.03690
Opus 5.5 $0.01476 $0.01476
Sonnet 5.5 $0.00738 $0.00738
Haiku 4.5 $0.00369 $0.00369

Measured 3d ago against content hash 0b24aa4352c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

btw 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.

AGENTS.md · 353 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

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.

  1. 3d ago Changed · +58 tokens per session 0b24aa4352c3
  2. 2mo ago First seen · 353 lines · 3,632 tokens per session scan A 060d1893c156

Subscribe to this mod's changes

btw AGENTS.md is an instructions file published in the GitHub repository posit-dev/btw (145 stars, last pushed 4d ago), with no licence file. It adds 3,690 tokens to every session, about $0.0148 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.

Related

btw AGENTS.md compared with instructions from other repositories

btw AGENTS.md next to 6 instructions from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
btw AGENTS.mdposit-dev/btwInstructions file1454d agononeA3,690Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA9,719GitHub Copilot
next.js AGENTS.mdvercel/next.jsInstructions file143ktodayMITA7,461Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchainInstructions file149kyesterdayMITA4,680Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA5,516GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA3,093GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harnessInstructions file274k2d agoMITA4,313Codex, OpenCode