PUT /api/media-items/:id (the metadata editor) writes the FULL row via
UpdateMediaItem, whose query sets audio_metadata unconditionally — and
audio_metadata has no editor field, so the params literal left it nil
and every save NULLed the payload. A plain metadata edit (genre tweak,
title rename) dropped any audiobook back to "1 second long" with no
track manifest: the same incident class as the scanner wipe, sitting
on the most-used admin path in the app.
Carry existing.AudioMetadata through the write. Write-after-success:
only the audio chain (probe-backed extraction /
UpdateMediaItemAudioBookPayload) ever replaces that column.