Borrowing it
Nothing to install: this file belongs to slopstopper/plumb-line. 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/slopstopper/plumb-line/main/AGENTS.mdgit clone --depth 1 https://github.com/slopstopper/plumb-lineWrote 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/slopstopper/plumb-line/agents-md)<a href="https://agentmods.dev/instructions/slopstopper/plumb-line/agents-md"><img src="https://agentmods.dev/badge/instructions/slopstopper/plumb-line/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/slopstopper/plumb-line/agents-md"><img src="https://agentmods.dev/badge/instructions/slopstopper/plumb-line/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 | $0.01875 | $0.01875 |
| Opus 5.5 | $0.00750 | $0.00750 |
| Sonnet 5.5 | $0.00375 | $0.00375 |
| Haiku 4.5 | $0.00187 | $0.00187 |
Grade A, and why
plumb-line 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 27d 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.
How it starts
The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md — plumb-line
Instructions for coding agents working in this repository, and the map a new contributor needs to find everything else.
This file deliberately points rather than copies. Every durable fact about this repo already lives in a committed document; restating values here would create a second source of truth that drifts — the failure this repo exists to prevent. What is written here is what you cannot get by reading one file: which file, and that it matters.
Where things are written down
| You need | It is in |
|---|---|
| How to build and test each component | DEVELOPMENT.md |
| How to contribute, and what a PR must satisfy | CONTRIBUTING.md |
| How releases are cut and published | RELEASING.md |
| The nine principles this project enforces — and is held to | reference/portable-principles.md |
| The envelope schema (the formal spec) | primitives/SPEC.md |
| The two API shapes, JS vs Python | docs/api.md |
| Cross-language parity, and the case table that enforces it | primitives/PARITY.md, primitives/conformance/cases.json |
| What is guaranteed, and what is only tamper-evident | docs/threat-model.md, SECURITY.md |
| Exact-valued global constraints (versions, floors, contracts) | docs/constraints.md |
| Why a past decision was made | docs/adr/ — append-only |
| What is planned, and how the backlog is organised | ROADMAP.md |
| This repo's tracking vocabulary and modules | docs/tracking-dialect.md |
Four things that are load-bearing
Each is documented above. They are repeated here as warnings because each is something an agent gets wrong by acting on a reasonable default.
- There is no root test command. No root
package.json. Each component is tested from its own directory. Running "the tests" from the repo root tests nothing. SeeDEVELOPMENT.md. - Parity is the central invariant. JS and Python must behave
identically. When you change combination or audit behaviour, change
both implementations and add a row to
cases.json. A divergence failing one suite is the system working. Never "fix" parity by editing prose — fix the code or the case table. - This repo is held to its own principles. The rules the audit skill
applies to other people's code apply here. Don't launder uncertainty,
hardcode a prior, or overstate maturity; use the maturity vocabulary
(
current/planned), not aspirational claims. - New behaviour needs a failing test first. Enforcement is proven by tests, not asserted.
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.
- 27d ago Changed · +4 lines · +77 tokens per session 5b89e0af9082
- 1mo ago Changed · +1 lines · +24 tokens per session 321539b90c1d
- 1mo ago First seen · 140 lines · 1,774 tokens per session scan A fcc17f8d70d9
plumb-line AGENTS.md is an instructions file published in the GitHub repository slopstopper/plumb-line (4 stars, last pushed today), licensed Apache-2.0. It adds 1,875 tokens to every session, about $0.0075 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.
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).
deno copilot-instructions.md
Copilot instructions for denoland/deno, covering deno development guide for github copilot, network access, high level overview, key directories and key files to understand first.