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.
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 skills add Asymptote-Labs/agent-beacon --skill beacon-lens-creategit 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/skills/asymptote-labs/agent-beacon/beacon-lens-create)<a href="https://agentmods.dev/skills/asymptote-labs/agent-beacon/beacon-lens-create"><img src="https://agentmods.dev/badge/skills/asymptote-labs/agent-beacon/beacon-lens-create/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/skills/asymptote-labs/agent-beacon/beacon-lens-create"><img src="https://agentmods.dev/badge/skills/asymptote-labs/agent-beacon/beacon-lens-create.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 | $0.00129 | $0.03385 |
| Opus 5.5 | $0.00052 | $0.01354 |
| Sonnet 5.5 | $0.00026 | $0.00677 |
| Haiku 4.5 | $0.00013 | $0.00338 |
Grade A, and why
beacon-lens-create 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 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.
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 — 233 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Beacon lens create
A lens is one self-contained HTML file that renders one agent trace: the prompts, agent
messages, tool calls, commands, file edits, approvals, token usage and threat-rule findings
Beacon recorded for a session. The local dashboard (beacon endpoint dashboard) shows lenses as
tabs on a session's page, next to Full session, and runs each one in a locked-down frame.
You write the file, check it against the user's real sessions, and install it. Nothing is published anywhere: lenses live on this machine.
Step 1: check that Beacon is available
beacon version
If beacon is not found, tell the user that lenses need the Beacon CLI, point them to
https://docs.beacon.sh/get-started/overview, and stop. Do not install it yourself.
Step 2: decide what the lens shows
Start from the user's description. If it is missing, or leaves a choice open that changes what the numbers mean (what counts as a "turn", a "failure", a "risky" command, which cost total), ask one focused question before building. Define each unit from this request, not from another lens, and label anything derived or estimated as such.
Step 3: read the spec and the real data
beacon lenses spec # the format, the data, the sandbox, the style tokens
beacon lenses spec --example # a complete working lens to start from
beacon lenses list # lens ids already in use
beacon lenses data # exactly what getTrace() returns for the latest session
beacon lenses data --session <session-id>
Read the whole spec before writing anything. Then look at real data rather than guessing its
shape from the spec: note which event types the user's sessions carry, whether file.diff,
command.output or usage is present, and whether findings exists. Design for those, and for
sessions that lack them. The output contains whatever content the log retained (prompts, command
output, diffs), so read it locally and do not paste large amounts back to the user.
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 · +8 lines b23c1bad1613
- 10d ago First seen · 225 lines · 129 tokens per session scan A c9bb7f49aefa
beacon-lens-create is a skill published in the GitHub repository Asymptote-Labs/agent-beacon (1,834 stars, last pushed today), licensed MIT. It adds 129 tokens to every session and 3,385 once invoked, about $0.0005 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 2026-10-06.
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