A power-cut on the speaker's NAND can leave a datastore file present but 0-byte
(a not-yet-flushed atomicWriteFile write). The read paths now treat empty/0-byte/
unparseable Presets/Recents/Sources the same as missing: GetConfiguredSources
serves the managed defaults (so /full self-heals instead of wiping the speaker),
GetPresets/GetRecents return an empty list (no more HTTP 500 on the device-level
endpoints), and HasConfiguredSources reports a 0-byte file as absent (so the
create_default_sources health quick fix is offered again).
Read-side resilience only; the write-side durability fix (fsync in
atomicWriteFile) follows in a separate PR.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Tobias GesellchenandClaude Opus 4.8