When the server is unreachable, the device should keep displaying the last good image instead of going blank.
Scope (device/)
- Persist the last successfully fetched PNG to disk after each good pull.
- On a failed/timed-out fetch, redraw the cached image and retry on the next interval; do not clear the panel.
- Optional: a subtle stale indicator after N missed pulls.
Why
- Currently a real failure mode — a transient server/LAN hiccup blanks the panel. High reliability value, low effort.
When the server is unreachable, the device should keep displaying the last good image instead of going blank.
Scope (
device/)Why