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We run 15 AI agents on a production server with full shell access. One of them tried to rm -rf a directory it shouldn't have touched. Another started curling cloud metadata endpoints. We wrote some hardcoded rules to catch the obvious stuff, then realized we were building the same safety layer everyone else will need too. So we extracted it into a library.

Vigil is a deterministic rule engine that inspects AI agent tool calls before they execute. 22 rules across 8 threat categories: destructive shell commands, SSRF, path traversal, SQL injection, data exfiltration, prompt injection, encoded payloads, and credential exposure. It's not an LLM wrapper — we don't trust an LLM to guard another LLM. Pure pattern matching, zero dependencies, <2ms per check, works completely offline.

npm install vigil-agent-safety

import { checkAction } from 'vigil-agent-safety'; const result = checkAction({ agent: 'my-agent', tool: 'exec', params: { command: 'rm -rf /' }, }); // result.decision → "BLOCK" // result.reason → "Destructive command pattern" // result.latencyMs → 0.3

It plugs into MCP servers, LangChain tool chains, Express middleware, or anything else. MIT licensed, no API keys, no network calls, no telemetry.

This is v0.1 — probably too aggressive for some use cases. Next up is a YAML policy engine (v0.2) and an MCP proxy. We'd love feedback on the rule set, false positive experiences, and threat categories we're missing.

GitHub: https://github.com/hexitlabs/vigil

Hey HN! This is Michael from magicreader. We’ve just released a Chrome extension that enables you to read web articles in the style and length you prefer.

The idea is similar to Violentmonkey/Tampermonkey and Tweeks, but focused on reading. For example, let’s say you want to read a research paper online, but you’re not an expert in the domain. You can use magicreader to rewrite the paper for a general audience and swap this simplified version directly into the page. While you’re reading, you can seamlessly flip back and forth between the simplified version and the original.

How this is different from using Claude/ChatGPT: with magicreader, there’s no need to copy-paste the text into a chat window, and there is no sidebar. Instead, the HTML of the article simply changes in-place, maintaining the core reading experience.

We currently support the following use cases: - Shorten: shorten web articles in-place to read 4x faster - Simplify ("ELI5"): adapt specialist writing (e.g., research papers) for a general audience - De-spin ("Honest"): annotate marketing/PR materials to quickly spot unsupported claims - Clean: rewrite unclear or old-fashioned writing in a clean, modern style

Notes: - We don’t bypass paywalls. We only operate on text you can already view in your browser. - When you rewrite a webpage, we send the full HTML to our backend; the rewritten text is then locally stored in your Chrome extension storage. The extension only sends data to the backend when you actively invoke magicreader. We don’t track your browsing activity across pages. - We use AI to rewrite content, and AI can make mistakes. That’s why we made it easy to flip back and forth between the rewritten version and the original—without losing your place in the text.

Rewriting full web articles using large language models is expensive, so we’re offering a limited free tier plus two paid plans. We’re planning to expand the free tier by using smaller and on-device LLMs.

Demo video: https://youtu.be/pckMSxCFUDo

Chrome extension: https://chromewebstore.google.com/detail/magicreader/phncpke...

We'd love feedback, particularly on 1) which reading mode is most useful, 2) where it breaks on real sites, and 3) any suggestions you have for new features.

You can reply directly here or email me at michael@magicreader.com.