O3.15.3Last known locationdesign

The last known location serves recovery and forensics alike

Aliases: location snapshot · last seen · final fix

What it is

The moment a wipe executes, the device-side location history, last cell and Wi-Fi attachments, battery level and movement trail all vanish. The last known location — the final position snapshot retained server-side before the wipe — is where recovery starts and where a police report anchors. "Read the snapshot, then send the wipe" is not procedural tidiness; it is a hard constraint imposed by one-way information destruction.

Why it happens

Location data lives on the device, so wiping destroys the evidence — the snapshot must reach the server before the wipe does. For recovery, position plus timestamp yields a search radius and a credibility estimate (the older the fix, the more likely the device has moved); "last seen at X at time T" is the verifiable statement a report needs. For forensics, the snapshot is the only objective location record between loss and disposition, separating "lost at home" from "moved after leaving the owner" — which bears directly on theft-versus-loss classification. The snapshot's value decays with age because it is instantaneous, so Lost Mode keeps refreshing it, the wipe retains the final frame, and the wipe confirmation must echo "locating will end" — the decision to give up recovery should be made while facing its only remaining evidence.

Where it stops holding

Snapshot accuracy is bounded by the fix source (GPS outclasses cell positioning by orders of magnitude; indoors often only cell-level survives), and "last known" is not "last true position" — the device may have moved after reporting, which is why the timestamp must be as prominent as the coordinates. On the privacy side, continuous snapshots are location tracking: retention limits and access scope need constraint (owner-visible only, deleted when the recovery flow closes); law-enforcement access runs through legal process, a separate channel from what the owner's UI shows, and the two must not share permissions or presentation.

Applying it

  • The loss panel shows three elements always: position, timestamp, and fix source (GPS/network); a snapshot without a timestamp is explicitly marked untrusted.
  • The wipe confirmation echoes "after this, the device can no longer be located," making the abandonment of recovery explicit.
  • The server retains the final snapshot for a policy-defined period after the wipe (for reporting), then deletes automatically.
  • Verification: test with a device that reports a fix then goes offline — assert the panel still shows the timestamped snapshot, the snapshot survives the wipe per policy, and is fully deleted at expiry. All three legs need assertions.

Related

  • Same group: O3.15.1 Offline wipe latency · O3.15.2 Recovery versus protection · O3.15.4 Account–device ownership separation
  • Nearby: O3.07 Device loss · O2.03 Sensor use indicators
  • Search terms: last known location · find my device · location retention · device forensics

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https://hci.top/en/handbook/O3.15.3