beacon AGENTS.md

beacon AGENTS.md is an instructions file for Codex, OpenCode from chris-peterson/beacon. It costs 7,971 tokens per session, scanned B, original, MIT.

A project instruction file for AI coding agents working on Beacon, a tool that shows the state of multiple coding sessions in a terminal or iTerm2.

In plain words
What is it for?
Use it when asking an AI agent to modify Beacon while keeping its CLI, session view, iTerm2 display, and documented behavior consistent.
Why use it?
It gives agents the project’s specifications, documentation locations, boundaries, and important code paths so they can make changes without guessing.

Instructions file for CodexOpenCode

Installs and runs on its own, but its text points at files inside the plugin that ships it — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed.

Install

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.

agentmods
npx agentmods add instructions/chris-peterson/beacon/agents-md
Clone the repo
git clone --depth 1 https://github.com/chris-peterson/beacon

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 beacon AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/chris-peterson/beacon/agents-md.svg)](https://agentmods.dev/instructions/chris-peterson/beacon/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/chris-peterson/beacon/agents-md"><img src="https://agentmods.dev/badge/instructions/chris-peterson/beacon/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 7,971 This file is loaded in full into every session.
When invoked 7,971 The same file — it is already loaded in full.
Security scan B 1 finding. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.07971 $0.07971
Opus 5 $0.03986 $0.03986
Sonnet 5 $0.01594 $0.01594
Haiku 4.5 $0.00797 $0.00797

Measured today against content hash c1fae29e6b18, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

beacon AGENTS.md scanned grade B 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 today.

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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

- **Claude Code status line (STATUSLINE-01/02/03)** — footer rows Claude Code renders from `beacon statusline` (wired into `~/.claude/settings.json` by `install`, which writes that one key and never replaces a `statusLin
AGENTS.md · 150 lines

How it starts

The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.

beacon

Notes for AI coding agents working on beacon. Behavioral spec is SPEC.md (published to the docs site as /spec); user-facing docs are README.md. When the spec and the code disagree, ask — don't silently choose one.

What beacon is

A Claude Code plugin + sourceable zsh snippet + standalone CLI that surfaces session state two ways: a terminal-agnostic sessions view (wip / watch / serve, optionally kept always-on via beacon serve install) that reads across all sessions and paints no pane, and an iTerm2 per-pane render adapter (a status bar with action buttons, the tab color + two-line label, the window title; the badge is opt-in) for scanning concurrent panes without focusing each. Clicking a session in the dashboard raises its iTerm2 window (serve's POST /focusbeacon-iterm focus). Both read the same per-session state files — the single source of record; neither inverts that into a daemon. The sessions view works in any terminal; the iTerm2 adapter needs macOS + iTerm2.

Three deliverables, hard boundaries

Deliverable Path Owns
CLI bin/beacon-iterm Translating subcommands to iTerm2 control operations — OSC sequences for painted surfaces, Apple Events (focus to raise a window, set-name to set the window title). Stateless. No Claude awareness.
Plugin scripts/beacon, hooks/, commands/, rules/ Hook handlers, COR resolver for signals, slash command. rules/ holds ambient rules emitted at SessionStart by hooks/emit-rules.sh (e.g. keep-session-labeled — proactive task upkeep so the sessions view has signal standalone). Invokes the CLI for every iTerm2 write.
Shell shell/beacon.zsh Project name / branch / cwd — refreshed every prompt. Emits its own SetUserVar OSC by raw printf; calls the CLI for set-name. Never goes through the plugin.

The plugin and shell write to disjoint user-var slots so they never overwrite each other. Don't blur this boundary.

Read the full file on GitHub · 150 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.

  1. today Changed · +18 lines · +1,181 tokens per session c1fae29e6b18
  2. 3d ago First seen · 132 lines · 6,790 tokens per session scan B d9011ad07ae0

Subscribe to this mod's changes

beacon AGENTS.md is an instructions file published in the GitHub repository chris-peterson/beacon (1 stars, last pushed today), licensed MIT. It adds 7,971 tokens to every session, about $0.0399 per session on Opus 5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other instructions, from other repositories