Agent Beacon is a local-first memory layer that records AI coding-agent sessions and turns useful workflows, corrections, and debugging patterns into knowledge that other agents can reuse. Developers use it across Claude Code, Cursor, Codex, OpenCode, and other agent harnesses so lessons and repository conventions persist between sessions. The catalogue entries provide instructions and a skill for working with Beacon's shared agent memory.
Borrowing it
Nothing to install: this file belongs to Asymptote-Labs/agent-beacon. 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/Asymptote-Labs/agent-beacon/main/AGENTS.mdgit clone --depth 1 https://github.com/Asymptote-Labs/agent-beaconWrote 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/asymptote-labs/agent-beacon/agents-md)<a href="https://agentmods.dev/instructions/asymptote-labs/agent-beacon/agents-md"><img src="https://agentmods.dev/badge/instructions/asymptote-labs/agent-beacon/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/asymptote-labs/agent-beacon/agents-md"><img src="https://agentmods.dev/badge/instructions/asymptote-labs/agent-beacon/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 | $0.00580 | $0.00580 |
| Opus 5.5 | $0.00232 | $0.00232 |
| Sonnet 5.5 | $0.00116 | $0.00116 |
| Haiku 4.5 | $0.00058 | $0.00058 |
Grade A, and why
agent-beacon 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 1mo 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 — 58 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent instructions for agent-beacon
Beacon is a local-only endpoint telemetry agent for AI runtimes. Guidance for working in this
repository lives in CONTRIBUTING.md (layout, workflow, validation) and CLAUDE.md (project
scope, product posture, release process). Read those first for ordinary changes.
Verifying a change end to end
This repository ships a sandbox that runs a real Claude Code session against the Beacon under test and checks whether Beacon captured what happened. Use it when asked to verify that a change actually works, not just that it compiles and unit-tests pass.
Read beacon-sandbox/AGENTS.md before running any verification. It is the operating manual:
prerequisites, which scenario to pick for which change, how to read a verdict, and the failure
modes that look like Beacon bugs but are not.
Start with the prerequisite check, which is free and needs no sandbox:
cd beacon-sandbox && go run ./cmd/beacon-sandbox doctor
Two things to know before you run anything: a scenario costs real money (roughly $0.06 of sandbox plus a few cents of API), so tell the user before spending it; and the sandbox is Linux-only, so it cannot verify macOS-specific behavior.
Running the standard checks
Unit and integration tests for the shipping code, per CONTRIBUTING.md:
cd cli/beacon && go test ./...
cd cli/beacon && go test -race ./internal/endpoint/...
cd cli/beacon-hooks && go test ./...
cd collector-builder/exporter/beaconjsonexporter && go test ./...
cd pkg/asymptoteobserve && go test ./...
sh packaging/macos/test-endpoint-scripts.sh
sh packaging/macos/smoke-endpoint.sh
Each directory above is a separate Go module; run Go commands from inside the module you are changing.
The npm and bun subprojects are separate from the Go modules and are not covered by the commands above:
cd packages/asymptote-sdk-js && npm ci && npm test && npm run check
cd browser-extension && npm ci && npm run check && npm run test:unit
cd plugins/opencode-beacon && bun run check && bun test
cd plugins/cline-beacon && bun run check && bun test
cd plugins/pi-beacon && bun run check && bun test
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.
- 1mo ago First seen · 58 lines · 580 tokens per session scan A e500769c965b
agent-beacon AGENTS.md is an instructions file published in the GitHub repository Asymptote-Labs/agent-beacon (2,808 stars, last pushed today), licensed MIT. It adds 580 tokens to every session, about $0.0023 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.
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.