# PDR 008: Use old phones for mobile evidence and outage detection

- HTML version: https://robbiepalmer.me/projects/homelab/pdrs/008-use-old-phones-for-mobile-evidence-and-outage-detection
- Project: Home Lab
- Status: Proposed
- Opened: 2026-08-22

## Context

Three working phones no longer have a daily job. They are poor replacements
for existing servers, but they have real mobile browsers, touch input,
batteries, and mobile radios that the servers lack.

Web changes currently rely on desktop browsers and emulators. Lab monitoring
also shares fate with home power, broadband, and DNS, so it may be unable to
report a total outage.

## Proposed decision

Use the old phones where their physical capabilities produce evidence the
servers cannot. Make them a small device pool for repeatable pull-request checks
on old and current Android browsers and iOS 15 Safari. Return screenshots,
device metadata, and a clear result to the agent that requested the check.

After the device-lab workflow works, use one Android phone on mobile data as an
outside observer for DNS, power, and broadband failures. Keep its network path
and alert credential independent from the home systems it checks.

Do not turn the phones into general servers or broad tailnet members. Keep
their stock operating systems because their real browser versions are the
point, and retire a device when its battery becomes unsafe.

## Consequences

The lab gains evidence from real mobile hardware and an observer outside its
main failure domain. It also gains USB state, signing, stale operating systems,
battery care, and a narrow but real access-control boundary.

## Evaluation

Accept the device-lab part when an agent can run a protected-preview smoke test
and collect reproducible evidence from both Android devices and the iPhone.
Accept the watchdog part only after deliberate resolver and home-network
failures produce an alert over mobile data.

## Migration note

This PDR extracts the proposed supported workflows and success conditions from
ADR 012. ADR 012 retains the USB, browser automation, stock operating-system,
power, and tailnet architecture. The migration does not claim that either
pilot has passed.

## Related records

- Project: [Home Lab](https://robbiepalmer.me/projects/homelab.md)
- Implemented by ADR: [ADR 012: Old phones as a physical device lab and cellular watchdog](https://robbiepalmer.me/projects/homelab/adrs/012-phone-device-lab.md)

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