DEV Community: yhc

I Spent the Last Few Days Testing AI Agents and Got Scared — So I Built Sentinel v0.3.0

yhc — Sat, 30 May 2026 02:17:02 +0000

Hey dev.to community 👋

Over the past few days, I’ve been running dozens of AI Agent experiments. The more powerful they got, the more nervous I became.

They can do amazing things, but they’re also shockingly easy to jailbreak, abuse tools, or quietly exfiltrate data. And once they go rogue? Traditional “safety inside the agent” approaches just don’t cut it.

So I decided to solve it differently.

The Solution: Sentinel v0.3.0 “The Shield Release”
I pulled the entire security layer completely outside the agent using an independent Shield Sidecar process.
The agent literally cannot see it or kill it. Every risky action (shell commands, file I/O, API calls, etc.) must request permission from the Shield first.

Key Features
• Shield Sidecar — True out-of-band protection + instant SIGKILL + forensic snapshot
• Deterministic Shadow Sandbox — Preview any action safely before it touches your real system
• Red Team Engine — 34 attack vectors, auto scoring (0-100)
• EU AI Act Compliance — One-click report generation
• Python @protect decorator + LangChain plugin
• Clean dashboard for monitoring + one-click kill

Full project here: https://github.com/byte271/Sentinel
Still very early (v0.3.0 just dropped), but I’m really happy with the direction — strong focus on determinism, auditability, and local-first.
If you’re building AI Agents, I’d love your honest feedback. What safety problems are you running into the most?
Let me know in the comments! 🔥

Introducing Qyavix — a 155-byte DOM runtime

yhc — Wed, 10 Dec 2025 02:42:17 +0000

I recently built a tiny experiment: a minimal DOM runtime that provides hooks-style state and re-rendering… in just 155 bytes. Yes — bytes, not kilobytes.

🌿 What is Qyavix?

Qyavix is an extremely small JavaScript runtime that provides:

A simple state hook (u)
A tiny render function (r)
Zero dependencies
No bundler required
Full DOM rendering
Only ~10 lines of code (minified to 155 bytes)

Ideal for micro-UIs, benchmarks, or experiments.

⚡ The entire runtime (155 bytes)

let h = [], i, R;
export const u = v => {
  let k = i++;
  return [h[k] ??= v, n => (h[k] = n?.call ? n(h[k]) : n, R())];
};
export const r = (C, e) => (R = () => { i = 0; e.replaceChildren(C()) }, R());

🧩 How it works

u() — state hook: creates state slots based on call order and triggers render when updated.

r() — render function: resets state index, calls your component, replaces DOM. No virtual DOM or diff.

🚀 Quick example

import { u, r } from "./Qyavix.js";

function App() {
  const [count, setCount] = u(0);
  const btn = document.createElement("button");
  btn.textContent = "Count: " + count;
  btn.onclick = () => setCount(c => c + 1);
  return btn;
}

r(App, document.getElementById("root"));

🌐 Live demo / Official site

The official site qyavix.pages.dev uses Qyavix itself to render — no framework, no build step, pure JS + 155-byte runtime.

📦 GitHub Repository

github.com/Yinhao-c/Qyavix

💬 Feedback welcome

If you try Qyavix or have ideas — suggestions, bugs, improvements — feel free to open issues or PRs. Every star / comment helps ❤️

How I Built CyhTabs — A Minimal, Privacy-Friendly Tab Manager That Just Works

yhc — Sat, 18 Oct 2025 18:39:51 +0000

Tired of messy tab chaos? Meet CyhTabs — a tiny, fast browser extension that saves your window as named tab groups and restores them instantly.

💡 Why I Built It

Every time I switched tasks, I hated losing my browsing context — dozens of tabs scattered everywhere.

I wanted something that’s:

Instant to use
Privacy-first (no remote servers)
Lightweight and safe

So I built CyhTabs, a simple browser extension that saves and restores tab groups locally — with a single click.

⚙️ What It Does

🏷️ Save & name your tab groups (title + timestamp)
🚀 One-click restore (open all group tabs in a window)
💾 Local-only storage (nothing uploaded)
🧩 Lightweight popup UI

No clutter, just productivity.

🧭 Quick Start

🔸 Firefox (recommended)

Install from Mozilla Add-ons: 👉 https://addons.mozilla.org/en-US/firefox/addon/cyhtabs/
Pin the icon and try saving your first group!

🔸 Chrome / Edge

Download from GitHub Releases: 👉 https://github.com/Yinhao-c/CyhTabs/releases
Go to chrome://extensions/ → enable Developer mode
Click Load unpacked → select the folder containing manifest.json
Pin the extension and test Save → Name → Restore

🌟 Why It's Useful

Restore your entire research/work session anytime
Keep your workflow private — all data stays local
No signup, no sync, no background bloat

🧠 Under the Hood

Uses chrome.storage.local (and Firefox equivalent)
Built with Manifest V3 service worker model
Event-driven background for reliability and low memory
Minimal permissions for security

If you want to peek under the hood, all code is open and commented in the repo.

🧩 For Developers

// Simple example: restore saved group
chrome.storage.local.get("groups", ({ groups }) => {
  groups.forEach(group => {
    group.urls.forEach(url => chrome.tabs.create({ url }));
  });
});

🧰 Troubleshooting

Popup blank? → Right-click → Inspect → Console for errors
Missing groups? → Check your browser’s storage settings
File an issue with steps & a short GIF if possible

🤝 Contribute

GitHub Repo → https://github.com/Yinhao-c/CyhTabs/

Issues, PRs, and feedback are always welcome!

Contact → yihac1@outlook.com

🌈 Final Thoughts

If you juggle multiple projects or research topics, give CyhTabs a try.

Install it, save your sessions, and take back control of your tabs.

If you find it helpful, please ⭐ the repo or leave a short review on AMO — it helps more users discover it!

👉 Firefox Add-on Page

👉 GitHub Repository

Built with love and too many tabs 💻