A tutorial runtime that demonstrates how to build a custom Avocado OS extension. The running example is a device heartbeat service — a shell script that collects system vitals (uptime, memory, load) and logs them as structured JSON to the journal. No compile step required.

• Build a custom extension using only overlay files and a systemd service
• Collect system vitals from /proc and output structured JSON to the journal
• Configure the heartbeat interval via a config file in the overlay
• Includes Avocado Connect and Tunnels extensions for remote device access