Chrome Auto-Refresh
The Problem
Chrome can discard inactive tabs and kill Manifest V3 service workers at any time. A naive setInterval() auto-refresh extension loses its timers under both conditions.
The Fix
Uses the Chrome alarms API for persistent per-tab timers, rehydrates remaining delay after service worker restarts, and cleans up stale entries when tabs are discarded. The popup and toolbar badge show a live countdown without needing the popup open.