The Sentinel blog
Notes on website monitoring, security practice, and the unglamorous work of keeping things online.
Agents can hold funded wallets now, so I catalogued what they can actually spend them on: a curated directory of live agent-payable APIs (x402 and MPP), organized by the capability gap each fills, with every listing continuously verified by a real uptime monitor.
Uptime alerts where your team already works: the official Sentinel Slack app is now listed on the Slack Marketplace, with per-channel installs, severity filtering, and a permission surface of exactly one capability.
PHP warnings above a WordPress header, stack traces from a failed deploy, database errors in the response: Sentinel now detects server-side errors automatically during normal HTTP monitoring, with no keywords to configure or maintain.
"My hosting company already monitors my site" is half true. The host watches its infrastructure, for its own SLA, from inside its own network. Expired certs, broken checkouts, DNS mistakes, and the question of who finds out first are all outside that scope.
Every incident starts with the same question: did we just ship? Deploy markers draw the answer directly on the response-time chart, cite deploys beside incidents, and can pause monitoring while a deployment runs.
Slack is a business signal and Discord is a hobbyist signal, so gating Discord monetized nobody. The reasoning behind the pricing change, and what the free plan includes now.
Our Slack app asks for one scope. Our GitHub app holds no credentials at all. Why minimal permissions shaped what got built, what that constraint costs, and why the consent screen is part of the product.
A status code tells you the server answered, not that it answered with your website. Why managed hosts serve error pages at 200, and why a keyword check that asserts your headline is present beats one that hunts for the word "error".
Alerts tell you when something changes. They cannot tell you that nothing has, which is the failure agencies actually fear. Why passive awareness beats another dashboard, and where a menu bar app fits.
AI can write your app in an afternoon, but it won't tell you when it's down. Why vibe-coded apps need uptime, SSL, and heartbeat monitoring, and how to add it in minutes.
Set up your first monitor in about 60 seconds and let us do the watching.
Posts here are drafted with AI assistance and edited by me. The ideas, the decisions they describe, and every factual claim are mine.