How should smart glasses show that navigation directions are out of date?
The display should distinguish a current route instruction from one based on stale location or a lost connection. An old arrow can look as authoritative as a fresh one unless the interface exposes that change. The appropriate signal depends on what information has stopped updating.
Expire the instruction when its basis is lost
A clear “Location unavailable” or paused-navigation state tells the wearer why guidance cannot continue confidently. Simply leaving the last arrow on screen hides the failure. A timestamp can help with diagnostics, but the main interface needs a status a person can understand at a glance.
Simulate a lost location update separately from a phone connection loss. The app should handle both without presenting an old instruction as current, then make it clear when reliable guidance resumes.