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Device Sentinel

Device Sentinel watches your hardware. It detects frozen devices (silent but showing a healthy value), unavailable devices, and low batteries, by learning each device's own reporting rhythm and setting per-device freeze windows automatically. Every detection reaches a problem list you act on, and a daily brief writes it up in plain language and emails it on its schedule.

Everything runs on sensible defaults from the moment it is installed. There is one thing to configure: for alerts to reach your phone, Device Sentinel must be told where to send them, on the Notifications and Daily Brief screen.

The Configuration Screens

Open Settings, then Devices and Services, then Device Sentinel, then Configure.

• Notifications and Daily Brief: where alerts go, quiet hours, and when the daily brief is sent.
• Global Exclusions: hardware you never want judged or reported, by anything.
• Low Battery: the low threshold, and battery-only excludes.
• Signal Strength: how weakening radio links are judged against a line just above each device's own learned floor, and the colored dwell chart that puts the whole fleet on one page. Three sliders tune it; alerting is still to come.
• Freeze Detection: how long a device may go quiet before it is called frozen, unavailable, or unknown. Set by two grace sliders.
• Advanced: settings most people never need to change.
• Recovery: not yet built. Attempts to revive frozen or offline devices.

Understanding What It Does

• How Device Sentinel Learns: the rhythm, the windows, and why there is no fixed timeout anywhere.
• The Device Page: what every sensor and button means.
• The Daily Brief: the report written for a person, every day, in plain language, and emailed on its schedule.
• The Reports: the dwell chart beside it, and the three diagnostic files behind both.
• The Problem List: how a detection reaches the list, and what the checkbox does.
• The Bridge Sensors: the per-coordinator sensor that shows running, binding, or down, and how to turn on the one for your system.
• Built to Be Efficient: how writing is kept down, and what to set on an SD card.
• FAQ and Troubleshooting

Reporting a Problem

Open an issue at the issue tracker and attach your diagnostics: Settings, Devices and Services, Device Sentinel, then the three-dot menu, then Download Diagnostics. The diagnostics carry the learned state and settings in effect and answer most questions without a screenshot. Notification targets are redacted automatically.