What is plain-forge AGENTS.md?

Repository instructions for plain-forge, an npm package that installs instructions teaching AI coding agents to create and maintain plain specification files. Its installer copies these files into an agent directory; another tool turns the specifications into code.

It helps developers install, update, or remove plain-forge, run its Node.js tests, and edit the skills and rules under the forge directory.

It explains which parts of the repository contain the installer and which contain the instructional content, reducing confusion when making changes or running tests.

How plainlang/plain-forge configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to plainlang/plain-forge. 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/plainlang/plain-forge/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/plainlang/plain-forge

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/plainlang/plain-forge/agents-md/github.svg)](https://agentmods.dev/instructions/plainlang/plain-forge/agents-md)

Your own site

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

Per session 2,733 This file is loaded in full into every session.

When invoked 2,733 The same file — it is already loaded in full.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.

Origin original 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	$0.02733	$0.02733
Opus 5.5	$0.01093	$0.01093
Sonnet 5.5	$0.00547	$0.00547
Haiku 4.5	$0.00273	$0.00273

Measured 4d ago against content hash 52f1fd00ce5d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

plain-forge AGENTS.md scanned grade A with 1 finding 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 4d 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

- `test/cli.test.mjs` mixes unit tests (importing named exports from `bin/cli.mjs`) with black-box integration tests that `spawnSync` the real CLI into isolated temp `HOME`/cwd dirs.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

plain-forge CLAUDE.md — 100% identical, 0 lines differ

AGENTS.md · 88 lines

How it starts

The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

What this repo is

plain-forge is an npm package with two distinct halves:

A tiny installer CLI (bin/cli.mjs) — npx plain-forge install|update|uninstall.
The actual product under forge/ — a library of AI-agent skills and rules that teach an agent to author and maintain ***plain specification files. The CLI copies forge/ verbatim into an agent directory; there is no build step and no generated/committed output.

So a change here is almost always one of: (a) editing the installer CLI, or (b) editing the instructional content under forge/skills/ (the authoring rules live in forge/skills/load-plain-reference/rules/). These need different mindsets — see "Editing forge/ content" below.

plain-forge only authors .plain specs. Rendering specs into code is done by a separate renderer, which this repo does not contain.

Commands

npm test                                                   # full suite: node --test test/*.test.mjs
node --test --test-name-pattern="<regex>" test/*.test.mjs  # run a single test by name
node --test test/cli.test.mjs                              # run a single test file

Test runner is Node's built-in node:test (node:assert/strict) — not jest/vitest, no test framework dependency. Requires Node ≥18.
test/cli.test.mjs mixes unit tests (importing named exports from bin/cli.mjs) with black-box integration tests that spawnSync the real CLI into isolated temp HOME/cwd dirs.
Releases are cut by publishing a GitHub Release tagged vX.Y.Z, which publishes to npm via OIDC — see RELEASING.md. The version lives in the tag, so package.json on main is intentionally stale.
There is no working build or lint step. package.json declares build/clean scripts (tsx bin/forge-build.ts) and tsconfig.json references bin/**/*.ts + runtimes/**/*.ts, but those files do not exist — npm run build/npm run clean error out. The TS toolchain (tsx/typescript) is vestigial; the CLI is plain .mjs run directly by Node. Don't try to build.

Read the full file on GitHub · 88 lines

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.

4d ago Changed · +43 tokens per session 52f1fd00ce5d
9d ago Changed · +9 tokens per session 5e3c4a3cc2c4
10d ago Changed · +242 tokens per session a4b5bdf84b7e
15d ago Changed · +6 lines · +158 tokens per session 4c8a7624bb91
1mo ago Changed · +88 tokens per session ae9765feeafb
2mo ago First seen · 82 lines · 2,193 tokens per session scan A a33dbbe706f5

Subscribe to this mod's changes

plain-forge AGENTS.md is an instructions file published in the GitHub repository plainlang/plain-forge (106 stars, last pushed yesterday), licensed MIT. It adds 2,733 tokens to every session, about $0.0109 per session on Opus 5.5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

plain-forge AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
plain-forge AGENTS.mdplainlang/plain-forge	Instructions file	106	yesterday	MIT	A	2,733	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

plain-forge: Instructions file for Codex