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/plainlang/plain-forge/claude-mdgit clone --depth 1 https://github.com/plainlang/plain-forgeWhat 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 | $0.02193 | $0.02193 |
| Opus 5 | $0.01097 | $0.01097 |
| Sonnet 5 | $0.00439 | $0.00439 |
| Haiku 4.5 | $0.00219 | $0.00219 |
Grade A, and why
plain-forge CLAUDE.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 2d 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. This is a copy
100% identical to plain-forge AGENTS.md — 0 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 — 82 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***plainspecification files. The CLI copiesforge/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/ and forge/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 tool, the codeplain CLI (codeplain.ai), 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.mjsmixes unit tests (importing named exports frombin/cli.mjs) with black-box integration tests thatspawnSyncthe real CLI into isolated tempHOME/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, sopackage.jsononmainis intentionally stale. - There is no working build or lint step.
package.jsondeclaresbuild/cleanscripts (tsx bin/forge-build.ts) andtsconfig.jsonreferencesbin/**/*.ts+runtimes/**/*.ts, but those files do not exist —npm run build/npm run cleanerror out. The TS toolchain (tsx/typescript) is vestigial; the CLI is plain.mjsrun directly by Node. Don't try to build.
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.
- 2d ago First seen · 82 lines · 2,193 tokens per session scan A a33dbbe706f5
plain-forge CLAUDE.md is an instructions file published in the GitHub repository plainlang/plain-forge (55 stars, last pushed 4d ago), licensed MIT. It adds 2,193 tokens to every session, about $0.0110 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). It is 100% identical to plain-forge AGENTS.md, differing in 0 lines, and is treated as a copy.
Other instructions, from other repositories
codex AGENTS.md
AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.
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
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, applying the notice (cutover) and fallback chain (never fail the build).
spec-kit AGENTS.md
AGENTS.md instructions for github/spec-kit, covering agents.md, about spec kit and specify, quickstart — add a new integration in 5 steps, integration architecture and integrationmanifest — file tracking.
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.